The flutter-by effect: a comprehensive study of the fluttering cusps of the Perceval heart valve prosthesis

The flutter-by effect: a comprehensive study of the fluttering cusps of the Perceval heart valve... Abstract OBJECTIVES Sutureless aortic valve prostheses are gaining popularity due to the substantial reduction in cross-clamp time. In this study, we report our observations on the cusp-fluttering phenomenon of the Perceval bioprosthesis (LivaNova, London, UK) using a combination of technical and medical perspectives. METHODS Between August 2014 and December 2016, a total of 108 patients (69% women) with a mean age of 78 years had aortic valve replacement using the Perceval bioprosthesis (34 combined procedures). All patients underwent transoesophageal echocardiography (TOE) intraoperatively. TOE was performed postoperatively to detect paravalvular leakage and to measure gradients, acceleration time, Doppler velocity indices (Vmax and LVOT/Vmax AV) and effective orifice area indices. In addition, a TOE examination was performed in 21 patients postoperatively. Data were collected retrospectively from our hospital database. RESULTS The retrospective evaluation of the intraoperative TOE examinations revealed consistent fluttering in all patients with the Perceval bioprosthesis. The echocardiographic postoperative measurements showed a mean effective orifice area index of 0.91 ± 0.12 cm2/m2. The overall mean pressure and peak pressure gradients were in a higher range (13.5 ± 5.1 mmHg and 25.5 ± 8.6 mmHg, respectively), whereas acceleration time (62.8 ± 16.4 ms) and Doppler velocity indices (0.43 ± 0.11) were within the normal range according to the American Society of Echocardiography or european association of echocardiography (EAE) guidelines. The 2-dimensional TOE in Motion Mode (M-Mode) that was performed in patients with elevated lactate dehydrogenase (LDH) levels revealed remarkable fluttering of the cusps of the Perceval bioprosthesis. CONCLUSIONS In our study cohort, we observed the fluttering phenomenon in all patients who received the Perceval bioprosthesis, which was correlated with elevated LDH levels and higher pressure gradients. Perceval bioprosthesis, Fluttering cusps, Sutureless valve INTRODUCTION Because of the steady increase in life expectancy rates across the globe, aortic valve replacements have become more common and are the treatment of choice for severe aortic valve stenosis with left ventricular dysfunction [1, 2]. Cases of severe aortic valve stenosis are fatal if untreated; 75% of patients die within 3 years of symptom onset [3]. More than 20% of patients undergoing conventional aortic valve surgery are older than 80 years [4]. Considering that conventional valve replacements pose challenges for high-risk patients, alternative sutureless valves have become increasingly common for elderly patients with notable comorbidities. The Perceval bioprosthesis (LivaNova, London, UK) is a sutureless valve that is often regarded as a preferable alternative to sutured valves because it reduces the cross-clamp and cardiopulmonary bypass times [5–9]. This is significant because extended cross-clamp time correlates with major postoperative morbidity and mortality in both low- and high-risk patients [10]. Therefore, this alternative valve is especially suitable for high-risk patients who do not meet the conditions for a transcatheter aortic valve implantation (TAVI) procedure and/or patients undergoing combined surgeries. Furthermore, the Perceval bioprosthesis can be implanted via ministernotomy, which reduces surgical trauma and may decrease intensive care unit stay and overall hospital stay [11–13]. The Perceval bioprosthesis has been the subject of extensive multicentre trials in Europe since 2007 [4]. The Perceval bioprosthesis is the most widely used sutureless prosthesis worldwide [4]. Furthermore, in January 2016, the Perceval bioprosthesis was approved by the United States Food and Drug Administration (FDA) [14]. MATERIALS AND METHODS Description of device The Perceval bioprosthesis includes a bovine pericardium secured to a nitinol cage stent (nickel and titanium alloy). The valve is crimped for implantation using a Perceval Dual Collapser device and then expands again to its original shape once placed using the Perceval Dual Holder. After the stent is deployed, the Perceval post-dilation catheter is used to optimize the contact area between the prosthesis and the aortic annulus [4, 14]. Four different valve size options are available for patients with annulus size between 19 mm and 27 mm: small (S) 19–21 mm; medium (M) 22–23 mm; large (L) 24–25 mm and extra large (XL) 26–27 mm. The Perceval bioprosthesis is not suitable for patients with an annular size larger than 27 mm [4]. Technical observation To better understand the mechanical behaviour of the prosthesis, the Perceval bioprosthesis was observed and handled at the Helmholtz Institute (Aachen, Germany) in the laboratory of the Cardiovascular Engineering Department. The bioprosthesis was inspected under a microscope (Keyence VHX-600, Keyence Deutschland GmbH, Neu-Isenburg, Germany), and its computational 3-dimensional design was reconstructed using the software PTC Creo Parametric 3.0 (PTC, Needham, MA, USA) to help with the visualization of its structure. Patients and data collection Between August 2014 and December 2016, data from all patients with aortic valve disease who had aortic valve replacement using the Perceval bioprosthesis, with or without concomitant procedures at our department, were analysed. Informed consent was waived by our ethics committee due to the retrospective nature of the study. Data were retrospectively collected from our clinic’s database and included medical history, echocardiographic assessments, intraoperative data and postoperative outcomes during the 30 postoperative days. Transthoracic and transoesophageal echocardiography assessments As a part of our clinical routine, all patients underwent postoperative transthoracic echocardiography (TTE) within 7 postoperative days in our department. In addition, transoesophageal echocardiography (TOE) was performed intraoperatively in all patients. Echocardiographic assessments were performed according to the guidelines of the European Association of Cardiovascular Imaging (EACVI) and the American Society of Echocardiography (ASE) [15]. TTE measurements performed at rest included transvalvular flow velocity using continuous-wave Doppler scanning and left ventricular outflow tract (LVOT) flow velocity using pulse-wave Doppler scanning. The LVOT diameter was assessed from the parasternal long-axis view. The transvalvular pressure gradient was calculated using the Bernoulli equation with the inclusion of subvalvular velocity and the effective orifice area using the standard continuity equation. The effective orifice area was indexed to the body surface area [effective orifice area index (EOAI)] [16, 17]. In addition to an evaluation of the left ventricular function, the assessment of the aortic valve included the following parameters: EOAI, mean pressure gradient (MPG), peak pressure gradient, flow acceleration time and Doppler velocity index ratio (Vmax LVOT/Vmax AV) [16, 17]. All echocardiographic studies were performed using the Vivid E9 (GE Vingmed Ultrasound AS, Horten, Norway), and the measurements were calculated using EchoPAC version 113 (GE Vingmed Ultrasound AS). In addition, TOE was performed in 21 patients postoperatively within 8 ± 2 postoperative days to rule out paravalvular leakage (PVL) and to assess the valve prosthesis performance relative to increased LDH levels (>500 U/l). Statistical analysis Because of the descriptive nature of our observations, no statistical evaluation was performed. Continuous variables are presented as mean ± standard deviation, and categorical variables are described as absolute numbers and percentages. RESULTS Clinical outcomes Between August 2014 and December 2016, a total of 108 patients (68% women) with a mean age of 77.6 years and a mean body mass index of 28.1 ± 4.5 kg/m2 received aortic valve replacements using the Perceval bioprosthesis (Table 1). Thirty-four patients underwent combined surgeries. Four patients died due to non-valve-related complications. In 2 cases, the Perceval bioprosthesis was removed and replaced with a conventional bioprosthesis due to severe central regurgitation caused by blocked cusps. In the 2 cases of the explanted Perceval valve, the valves were Size M and Size L. The replacement aortic valve was Dokimus® (23 mm) and Trifecta® (25 mm), respectively. Table 1: Patient characteristics Variables Size S Size M Size L Size XL (n = 14) (n = 33) (n = 45) (n = 16) Preoperative data  Age (years), mean ± SD 79 ± 5 77 ± 4 76 ± 4 76 ± 5  Female, n (%) 14 (100) 23 (69.7) 21 (46.7) 2 (12.5)  BMI (kg/m2), mean ± SD 28.1 ± 3.9 27.3 ± 5.4 28.5 ± 4.1 28.6 ± 3.3  KD, n (%) 2 (14.3) 5 (15.5) 4 (8.9) 3 (18.7)  COPD, n (%) 0 7 (21.2) 4 (8.9) 2 (12.5)  IDDM, n (%) 3 (21.4) 10 (30.3) 13 (28.9) 6 (37.5)  HLP, n (%) 6 (42.5) 9 (27.3) 24 (53.3) 7 (43.7)  PAD, n (%) 1 (7.1) 2 (6.1) 4 (8.9) 0  Prior AF, n (%) 3 (27.3) 6 (18.2) 12 (26.7) 9 (56.2)  Prior apoplexy, n (%) 0 3 (9.1) 5 (11.1) 3 (18.7)  EuroSCORE II (%), mean ± SD 2.9 ± 1.1 3.5 ± 1.9 3.4 ± 2.3 3.4 ± 1.6  Log EuroSCORE I, mean ± SD 8.5 ± 5.1 4.8 ± 3.4 6.2 ± 5.1 7.3 ± 5.0  Additive EuroSCORE I (%), mean ± SD 2.2 ± 0.7 1.7 ± 0.6 1.8 ± 0.7 2.0 ± 0.7 Perioperative data  Single AVR, n (%) 12 (85.7) 21 (63.6) 22 (48.9) 6 (37.5)  Combined surgery, n (%) 1 (7.1) 10 (30.3) 23 (55.5) 14 (87.5)  CPB time (min), mean ± SD 95.7 ± 22.3 101.1 ± 48 110.4 ± 42 133.6 ± 48.6  Cross-clamp time (min), mean ± SD 59.7 ± 15.4 64.6 ± 27.5 70.3 ± 24.3 85 ± 24.2 Postoperative data  AV block with PM implantation, n (%) 1 (7.1) 2 (6.1) 3 (6.7) 1 (6.2)  Delirium, n (%) 2 (14.3) 6 (18.2) 4 (8.9) 3 (18.7)  Ischaemic stroke, n (%) 0 1 (3) 2 (4.4) 0  Rethoracotomy due to bleeding, n (%) 0 2 (6.1) 3 (6.7) 2 (12.5)  AF, n (%) 3 (21.4) 11 (33.3) 11 (24.4) 1 (6.2)  Mild PVL, n (%) 3 (21.4) 3 (9.1) 3 (6.7) 1 (6.2)  Moderate PVL, n (%) 0 1 (3) 0 1 (6.2)  Severe PVL, n (%) 0 0 0 0  ICU stay (days), mean ± SD 2.9 ± 2.6 3.6 ± 4.6 5.1 ± 9.4 4.6 ± 8.5 Variables Size S Size M Size L Size XL (n = 14) (n = 33) (n = 45) (n = 16) Preoperative data  Age (years), mean ± SD 79 ± 5 77 ± 4 76 ± 4 76 ± 5  Female, n (%) 14 (100) 23 (69.7) 21 (46.7) 2 (12.5)  BMI (kg/m2), mean ± SD 28.1 ± 3.9 27.3 ± 5.4 28.5 ± 4.1 28.6 ± 3.3  KD, n (%) 2 (14.3) 5 (15.5) 4 (8.9) 3 (18.7)  COPD, n (%) 0 7 (21.2) 4 (8.9) 2 (12.5)  IDDM, n (%) 3 (21.4) 10 (30.3) 13 (28.9) 6 (37.5)  HLP, n (%) 6 (42.5) 9 (27.3) 24 (53.3) 7 (43.7)  PAD, n (%) 1 (7.1) 2 (6.1) 4 (8.9) 0  Prior AF, n (%) 3 (27.3) 6 (18.2) 12 (26.7) 9 (56.2)  Prior apoplexy, n (%) 0 3 (9.1) 5 (11.1) 3 (18.7)  EuroSCORE II (%), mean ± SD 2.9 ± 1.1 3.5 ± 1.9 3.4 ± 2.3 3.4 ± 1.6  Log EuroSCORE I, mean ± SD 8.5 ± 5.1 4.8 ± 3.4 6.2 ± 5.1 7.3 ± 5.0  Additive EuroSCORE I (%), mean ± SD 2.2 ± 0.7 1.7 ± 0.6 1.8 ± 0.7 2.0 ± 0.7 Perioperative data  Single AVR, n (%) 12 (85.7) 21 (63.6) 22 (48.9) 6 (37.5)  Combined surgery, n (%) 1 (7.1) 10 (30.3) 23 (55.5) 14 (87.5)  CPB time (min), mean ± SD 95.7 ± 22.3 101.1 ± 48 110.4 ± 42 133.6 ± 48.6  Cross-clamp time (min), mean ± SD 59.7 ± 15.4 64.6 ± 27.5 70.3 ± 24.3 85 ± 24.2 Postoperative data  AV block with PM implantation, n (%) 1 (7.1) 2 (6.1) 3 (6.7) 1 (6.2)  Delirium, n (%) 2 (14.3) 6 (18.2) 4 (8.9) 3 (18.7)  Ischaemic stroke, n (%) 0 1 (3) 2 (4.4) 0  Rethoracotomy due to bleeding, n (%) 0 2 (6.1) 3 (6.7) 2 (12.5)  AF, n (%) 3 (21.4) 11 (33.3) 11 (24.4) 1 (6.2)  Mild PVL, n (%) 3 (21.4) 3 (9.1) 3 (6.7) 1 (6.2)  Moderate PVL, n (%) 0 1 (3) 0 1 (6.2)  Severe PVL, n (%) 0 0 0 0  ICU stay (days), mean ± SD 2.9 ± 2.6 3.6 ± 4.6 5.1 ± 9.4 4.6 ± 8.5 AF: atrial fibrillation; AV: atrioventricular; AVR: aortic valve replacement; BMI: body mass index; COPD: chronic obstructive pulmonary disease; CPB: cardiopulmonary bypass; HLP: hyperlipoproteinaemia; ICU: intensive care unit; IDDM: insulin-dependent diabetes mellitus; KD: kidney disease; PAD: peripheral artery disease; PM: Pacemaker; PVL: paravalvular leak; SD: standard deviation. Table 1: Patient characteristics Variables Size S Size M Size L Size XL (n = 14) (n = 33) (n = 45) (n = 16) Preoperative data  Age (years), mean ± SD 79 ± 5 77 ± 4 76 ± 4 76 ± 5  Female, n (%) 14 (100) 23 (69.7) 21 (46.7) 2 (12.5)  BMI (kg/m2), mean ± SD 28.1 ± 3.9 27.3 ± 5.4 28.5 ± 4.1 28.6 ± 3.3  KD, n (%) 2 (14.3) 5 (15.5) 4 (8.9) 3 (18.7)  COPD, n (%) 0 7 (21.2) 4 (8.9) 2 (12.5)  IDDM, n (%) 3 (21.4) 10 (30.3) 13 (28.9) 6 (37.5)  HLP, n (%) 6 (42.5) 9 (27.3) 24 (53.3) 7 (43.7)  PAD, n (%) 1 (7.1) 2 (6.1) 4 (8.9) 0  Prior AF, n (%) 3 (27.3) 6 (18.2) 12 (26.7) 9 (56.2)  Prior apoplexy, n (%) 0 3 (9.1) 5 (11.1) 3 (18.7)  EuroSCORE II (%), mean ± SD 2.9 ± 1.1 3.5 ± 1.9 3.4 ± 2.3 3.4 ± 1.6  Log EuroSCORE I, mean ± SD 8.5 ± 5.1 4.8 ± 3.4 6.2 ± 5.1 7.3 ± 5.0  Additive EuroSCORE I (%), mean ± SD 2.2 ± 0.7 1.7 ± 0.6 1.8 ± 0.7 2.0 ± 0.7 Perioperative data  Single AVR, n (%) 12 (85.7) 21 (63.6) 22 (48.9) 6 (37.5)  Combined surgery, n (%) 1 (7.1) 10 (30.3) 23 (55.5) 14 (87.5)  CPB time (min), mean ± SD 95.7 ± 22.3 101.1 ± 48 110.4 ± 42 133.6 ± 48.6  Cross-clamp time (min), mean ± SD 59.7 ± 15.4 64.6 ± 27.5 70.3 ± 24.3 85 ± 24.2 Postoperative data  AV block with PM implantation, n (%) 1 (7.1) 2 (6.1) 3 (6.7) 1 (6.2)  Delirium, n (%) 2 (14.3) 6 (18.2) 4 (8.9) 3 (18.7)  Ischaemic stroke, n (%) 0 1 (3) 2 (4.4) 0  Rethoracotomy due to bleeding, n (%) 0 2 (6.1) 3 (6.7) 2 (12.5)  AF, n (%) 3 (21.4) 11 (33.3) 11 (24.4) 1 (6.2)  Mild PVL, n (%) 3 (21.4) 3 (9.1) 3 (6.7) 1 (6.2)  Moderate PVL, n (%) 0 1 (3) 0 1 (6.2)  Severe PVL, n (%) 0 0 0 0  ICU stay (days), mean ± SD 2.9 ± 2.6 3.6 ± 4.6 5.1 ± 9.4 4.6 ± 8.5 Variables Size S Size M Size L Size XL (n = 14) (n = 33) (n = 45) (n = 16) Preoperative data  Age (years), mean ± SD 79 ± 5 77 ± 4 76 ± 4 76 ± 5  Female, n (%) 14 (100) 23 (69.7) 21 (46.7) 2 (12.5)  BMI (kg/m2), mean ± SD 28.1 ± 3.9 27.3 ± 5.4 28.5 ± 4.1 28.6 ± 3.3  KD, n (%) 2 (14.3) 5 (15.5) 4 (8.9) 3 (18.7)  COPD, n (%) 0 7 (21.2) 4 (8.9) 2 (12.5)  IDDM, n (%) 3 (21.4) 10 (30.3) 13 (28.9) 6 (37.5)  HLP, n (%) 6 (42.5) 9 (27.3) 24 (53.3) 7 (43.7)  PAD, n (%) 1 (7.1) 2 (6.1) 4 (8.9) 0  Prior AF, n (%) 3 (27.3) 6 (18.2) 12 (26.7) 9 (56.2)  Prior apoplexy, n (%) 0 3 (9.1) 5 (11.1) 3 (18.7)  EuroSCORE II (%), mean ± SD 2.9 ± 1.1 3.5 ± 1.9 3.4 ± 2.3 3.4 ± 1.6  Log EuroSCORE I, mean ± SD 8.5 ± 5.1 4.8 ± 3.4 6.2 ± 5.1 7.3 ± 5.0  Additive EuroSCORE I (%), mean ± SD 2.2 ± 0.7 1.7 ± 0.6 1.8 ± 0.7 2.0 ± 0.7 Perioperative data  Single AVR, n (%) 12 (85.7) 21 (63.6) 22 (48.9) 6 (37.5)  Combined surgery, n (%) 1 (7.1) 10 (30.3) 23 (55.5) 14 (87.5)  CPB time (min), mean ± SD 95.7 ± 22.3 101.1 ± 48 110.4 ± 42 133.6 ± 48.6  Cross-clamp time (min), mean ± SD 59.7 ± 15.4 64.6 ± 27.5 70.3 ± 24.3 85 ± 24.2 Postoperative data  AV block with PM implantation, n (%) 1 (7.1) 2 (6.1) 3 (6.7) 1 (6.2)  Delirium, n (%) 2 (14.3) 6 (18.2) 4 (8.9) 3 (18.7)  Ischaemic stroke, n (%) 0 1 (3) 2 (4.4) 0  Rethoracotomy due to bleeding, n (%) 0 2 (6.1) 3 (6.7) 2 (12.5)  AF, n (%) 3 (21.4) 11 (33.3) 11 (24.4) 1 (6.2)  Mild PVL, n (%) 3 (21.4) 3 (9.1) 3 (6.7) 1 (6.2)  Moderate PVL, n (%) 0 1 (3) 0 1 (6.2)  Severe PVL, n (%) 0 0 0 0  ICU stay (days), mean ± SD 2.9 ± 2.6 3.6 ± 4.6 5.1 ± 9.4 4.6 ± 8.5 AF: atrial fibrillation; AV: atrioventricular; AVR: aortic valve replacement; BMI: body mass index; COPD: chronic obstructive pulmonary disease; CPB: cardiopulmonary bypass; HLP: hyperlipoproteinaemia; ICU: intensive care unit; IDDM: insulin-dependent diabetes mellitus; KD: kidney disease; PAD: peripheral artery disease; PM: Pacemaker; PVL: paravalvular leak; SD: standard deviation. In the 3rd case, the patient returned to cardiology department after 6 months with severe stenosis due to a blocked cusp [15] (Video 1 demonstrates the blockage of the valve leaflet in the position of right coronary cusp with TOE). The patient refused the reoperation and the secondary option of a valve in valve procedure (TAVI). The current condition of this patient is unknown. In both cases, the valve was easily explanted. Upon closer observation of the explanted valves, it was clear that the leaflets and the stents appeared normal and not deformed. Echocardiographic findings All patients underwent early postoperative echo studies. TTE was performed prior to discharge to detect PVL and measure gradients, acceleration time, ejection time (ET), Doppler velocity indices (Vmax LVOT/Vmax AV) and EOAI to the body surface area. The data were collected retrospectively from our hospital database (Table 2). Table 2: Echocardiographic analysis Parameters Size S (n = 14) Size M (n = 33) Size L (n = 45) Size XL (n = 16) MPG (mmHg) 13.4 ± 4.8 14.8 ± 6.1 12.4 ± 3.7 15.4 ± 6.4 PPG (mmHg) 24.8 ± 8.9 26.9 ± 9.7 23.5 ± 6.1 29.4 ± 10.2 EOAI (mm2) 0.65 ± 0.21 0.58 ± 0.17 0.73 ± 0.23 0.79 ± 0.22 AT (ms) 63.9 ± 16.7 62.3 ± 13.5 64.6 ± 14.3 57.4 ± 22.6 ET (ms) 241.7 ± 37.4 261.1 ± 32.4 260.4 ± 41.5 253.6 ± 26.6 DVI 0.47 ± 0.12 0.42 ± 0.10 0.44 ± 0.12 0.40 ± 0.10 Parameters Size S (n = 14) Size M (n = 33) Size L (n = 45) Size XL (n = 16) MPG (mmHg) 13.4 ± 4.8 14.8 ± 6.1 12.4 ± 3.7 15.4 ± 6.4 PPG (mmHg) 24.8 ± 8.9 26.9 ± 9.7 23.5 ± 6.1 29.4 ± 10.2 EOAI (mm2) 0.65 ± 0.21 0.58 ± 0.17 0.73 ± 0.23 0.79 ± 0.22 AT (ms) 63.9 ± 16.7 62.3 ± 13.5 64.6 ± 14.3 57.4 ± 22.6 ET (ms) 241.7 ± 37.4 261.1 ± 32.4 260.4 ± 41.5 253.6 ± 26.6 DVI 0.47 ± 0.12 0.42 ± 0.10 0.44 ± 0.12 0.40 ± 0.10 Values are presented as mean ± standard deviation. AT: acceleration time; DVI: Doppler velocity indices; EOAI: effective orifice area index; ET: ejection time; MPG: mean pressure gradient; PPG: peak pressure gradient. Table 2: Echocardiographic analysis Parameters Size S (n = 14) Size M (n = 33) Size L (n = 45) Size XL (n = 16) MPG (mmHg) 13.4 ± 4.8 14.8 ± 6.1 12.4 ± 3.7 15.4 ± 6.4 PPG (mmHg) 24.8 ± 8.9 26.9 ± 9.7 23.5 ± 6.1 29.4 ± 10.2 EOAI (mm2) 0.65 ± 0.21 0.58 ± 0.17 0.73 ± 0.23 0.79 ± 0.22 AT (ms) 63.9 ± 16.7 62.3 ± 13.5 64.6 ± 14.3 57.4 ± 22.6 ET (ms) 241.7 ± 37.4 261.1 ± 32.4 260.4 ± 41.5 253.6 ± 26.6 DVI 0.47 ± 0.12 0.42 ± 0.10 0.44 ± 0.12 0.40 ± 0.10 Parameters Size S (n = 14) Size M (n = 33) Size L (n = 45) Size XL (n = 16) MPG (mmHg) 13.4 ± 4.8 14.8 ± 6.1 12.4 ± 3.7 15.4 ± 6.4 PPG (mmHg) 24.8 ± 8.9 26.9 ± 9.7 23.5 ± 6.1 29.4 ± 10.2 EOAI (mm2) 0.65 ± 0.21 0.58 ± 0.17 0.73 ± 0.23 0.79 ± 0.22 AT (ms) 63.9 ± 16.7 62.3 ± 13.5 64.6 ± 14.3 57.4 ± 22.6 ET (ms) 241.7 ± 37.4 261.1 ± 32.4 260.4 ± 41.5 253.6 ± 26.6 DVI 0.47 ± 0.12 0.42 ± 0.10 0.44 ± 0.12 0.40 ± 0.10 Values are presented as mean ± standard deviation. AT: acceleration time; DVI: Doppler velocity indices; EOAI: effective orifice area index; ET: ejection time; MPG: mean pressure gradient; PPG: peak pressure gradient. We performed TOE in 21 patients to rule out PVLs and to assess valve prosthesis performance relative to increased MPG and LDH levels (>500 U/l). TOE in M-Mode led to the observation of the cusp-fluttering phenomenon. The repeated review of postoperative TTE did not reveal fluttering due to insufficient image quality. The review of intraoperative TOE, however, did reveal fluttering in all patients (78) whose TOE results were saved in the database. Fluttering phenomenon TOE in M-Mode led to the observation of the cusp-fluttering phenomenon. Usually, during the ventricular systole, the separated cusps of the aortic valve appear in box form in M-Mode. They remain open throughout the systole and sometimes demonstrate a fine fluttering motion [18]. The fluttering cusp phenomenon is defined by the abnormal behaviour of the Perceval cusps during the systole. During ejection, the cusps’ movements vary wildly between the edge and the base, often nearly coming to a complete close. As an initial point of reference, Fig. 1 depicts the normal performance of a biological aortic valve prosthesis (Carpentier-Edwards Perimount, Fig. 1A) and 5 additional examples of the remarkable fluttering of the Perceval bioprosthesis (Fig. 1B–F). Throughout the systole (Fig. 1A), both the RCC and ACC cusps are continually open in a parallel formation, not disturbing the laminar blood flow. During the entire systole phase, the effective orifice area remains constant. Compared to the normal cusp behaviour presented in Fig. 1A, the proximity of the Perceval bioprosthesis cusp edges to each other during the systole is easily observed, which could potentially disturb the regular blood flow of the patient. In some cases, the oscillation reaches a frequency of 15 Hz or approximately 1000 flutters/min (Fig. 1B). Planimetric measurements of the orifice area pose a challenge given the abnormal mobility of the valve cusps during the systole. The turbulence and aliasing effect reveal the functional stenosis of the valve as shown in Fig. 1E and F. The intermittent fluttering of the cusps results in irregular high velocity output. Figure 1: View largeDownload slide Contrasting valve cusp behaviour. (A) M-mode in the parasternal long axis showing normal bioprosthesis performance (Carpentier-Edwards Perimount®). (B–D) The fluttering cusp phenomenon that is unique to the Perceval bioprosthesis. The fluttering is also present at a lower frequency (C and D above). This cusp-fluttering phenomenon is also clearly visible in colour (E) and continuous Doppler (F). Figure 1: View largeDownload slide Contrasting valve cusp behaviour. (A) M-mode in the parasternal long axis showing normal bioprosthesis performance (Carpentier-Edwards Perimount®). (B–D) The fluttering cusp phenomenon that is unique to the Perceval bioprosthesis. The fluttering is also present at a lower frequency (C and D above). This cusp-fluttering phenomenon is also clearly visible in colour (E) and continuous Doppler (F). Observations from the technical examination of the Perceval bioprosthesis Several structural features distinguish the Perceval bioprosthesis from other widely used TAVI Nitinol prostheses. First, its frame is higher than comparable TAVI Nitinol prostheses [19, 20]. Second, the cusps’ commissures are sutured along 3 long vertical struts. This is a unique feature in the prosthesis valve design (Fig. 2) and contrasts with the continuous diamond structure and suturing pattern of comparable TAVI Nitinol prostheses [21]. Third, the Perceval frame is very flexible (radial force tests show that the Perceval stent is more flexible than other widely used stents) [20, 21]. Figure 2: View largeDownload slide The Perceval stent structure. Figure 2: View largeDownload slide The Perceval stent structure. Figure 2 shows an in-house 3-dimensional design reproduction of the Perceval stent following inspection of the frame under a microscope. Mainly, it consists of top and bottom ring structures that are connected by 3 thick struts (blue dotted line) and 2 thinner curved branches between each strut. The prosthetic cusps are sutured, and the commissures of the cusps are fixed to the 3 main struts (blue dotted lines). Considering the unique design of the Perceval stent and the way the cusps are attached to the stent, it appears that a small external deformation can lead to an abnormally stretched position of 1 or 2 cusps. Increased deformation can eventually lead to the full blockage of 1 or 2 cusps (depending on the stent orientation) [22]. We demonstrate an example of a blocked cusp of the Perceval bioprosthesis in Video 1. In Fig. 3, it is possible to observe that the slight ovalization of the prosthesis directly translates to a greater distance between Commissures C1 and C2 and tenses cusp L1. Figure 3: View largeDownload slide Ovalization of the stent. The slight ovalization of the prosthesis directly translates to a greater distance between Commissures C1 and C2 and tenses cusp L1. Figure 3: View largeDownload slide Ovalization of the stent. The slight ovalization of the prosthesis directly translates to a greater distance between Commissures C1 and C2 and tenses cusp L1. Video 1 Blockage of a Perceval bioprosthesis cusp. Transoesophageal echocardiography, 120°, blocked right coronary cusp of the Perceval bioprosthesis. Video 1 Blockage of a Perceval bioprosthesis cusp. Transoesophageal echocardiography, 120°, blocked right coronary cusp of the Perceval bioprosthesis. Close Depending on the orientation of the prosthesis deformation, 1 or 2 leaflets can be abnormally stretched, as demonstrated in Fig. 3. The fluttering of the cusp observed during echocardiographic examinations can be explained using an abnormally stretched cusp. The hypothesis that a Perceval bioprosthesis implanted in a patient can present 1 or 2 stretched cusps is verified by several aspects that are all specific to the Perceval bioprosthesis: The Perceval stent is very flexible and, therefore, prone to small deformation or ovalization in patients’ aortic anatomies. Comparably, computed tomography scan images show that widely used TAVI Nitinol prostheses are rarely perfectly circular [23, 24] in patients, and radial force tests show that the Perceval Nitinol stent is even more flexible than other widely used TAVI Nitinol stents [25]. Given the stent design (the 3 long vertical struts) and suturing pattern (the leaflet commissures attached to the long struts), deformation or ovalization of the stent translates directly into an increased distance between opposite commissures, with 1 or 2 stretched cusps depending on the valve orientation. DISCUSSION The fluttering cusp phenomenon exhibited by the Perceval bioprosthesis post-implantation was initially discovered during a transoesophageal echocardiographic examination in M-Mode. Observing the behaviour of the cusps in a 1-dimensional format revealed that there were abnormalities in the cusp dynamics. The irregular movements of the cusps can be best described as distinctly ‘fluttering’ throughout the systole, which is not present to the same extent in conventional sutured valves. A certain degree of fluttering is present naturally in most prosthetic valve cusps for a short instant before they are completely open and when they are in the open position, but it is not as extreme as is in the case of the Perceval bioprosthesis [18]. All patients had a low EOAI, but not all patients who exhibited the fluttering phenomenon had a high MPG. A high MPG was found only in 36% of patients, and in all patients, high LDH levels were recorded. Because of the distinct fluttering of the Perceval valve cusps throughout the systole, accurate planimetric measurements of the orifice area are relatively challenging. This impedes the accurate examination of valve performance and the interpretation of results when using traditional echocardiography parameters. One explanation for this phenomenon may be the design of the Perceval stent, which is very flexible and, therefore, prone to slight deformation or ovalization in patients’ aortic anatomies. Oversizing is an unlikely cause of the fluttering phenomenon because the Perceval-delivered sizing device was used in all cases throughout the study. Furthermore, in 2016, a cardiac surgeon hired by LivaNova proctored the Perceval implantation operation in more than 10 patients at the University Hospital Aachen Cardiac Surgery department. The fluttering phenomenon was present postoperatively in all these patients. Moreover, it is well documented that oversizing can lead to paravalvular aortic regurgitation, whereas oversizing to a higher degree may lead to a non-fully expanded prosthesis, central aortic regurgitation [25–27], acute valve failure and a very high transvalvular gradient [28]. In our observational study of the fluttering phenomenon, we did not encounter any relevant PVLs or central regurgitation. We observed higher gradients in patients with Perceval valves when compared to those with conventional valves, but the valves with gradients in a normal range showed remarkable fluttering, which is also an evidence against the notion that oversizing causes the fluttering. Our radial force test shows that the Perceval stent is very flexible, meaning that any small force leads to minor deformations of the stent during the heart cycle. These small deformations of the stent during the systole lead to the flutter phenomenon. Even appropriately sized Perceval prostheses are easily deformed from external forces during the systole due to the very low radial forces, which then causes the fluttering phenomenon. For these reasons, it can be deduced that the cusp-fluttering phenomenon is due to the problematic design of the Perceval stent and not simply a result of oversizing. A high degree of oversizing (non-fully expanded valve) leads to cusp folding and subsequently, cusp blockage. This was observed through transoesophageal echocardiographic examination which showed cusp thickening. The impact of the different degrees of oversizing on their performance of the valve should be studied further in the future. Further in vitro studies are required to analyse the fluttering phenomenon of the Perceval bioprosthesis, and long-term follow-up results are necessary to evaluate whether this fluttering phenomenon will result in early damage to the cusps. Continuous critical evaluations of medical practices and devices, including frequent and impartial multidisciplinary studies, are necessary to keep pace with innovations in the medical technology industry. In this way, medical professionals can avoid the pitfalls of prioritizing private interests over the long-term well-being of their patients. Limitations Although our data are limited by the usual shortcomings of a retrospective observational study, the uniform presentation of the phenomenon throughout all patients prevents a different study design. The major drawback is the lack of long-term data, which will be collected in the near future. Conflict of interest: none declared. REFERENCES 1 Iung B , Baron G , Butchart EG , Delahaye F , Gohlke-Barwolf C , Levang OW et al. A prospective survey of patients with valvular heart disease in Europe: the Euro Heart Survey on Valvular Heart Disease . Eur Heart J 2003 ; 24 : 1231 – 43 . Google Scholar CrossRef Search ADS PubMed 2 Funkat A , Beckmann A , Lewandowski J , Frie M , Ernst M , Schiller W et al. Cardiac surgery in Germany during 2012: a report on behalf of the German Society for Thoracic and Cardiovascular Surgery . Thorac Cardiovasc Surg 2014 ; 62 : 380 – 17 . Google Scholar CrossRef Search ADS PubMed 3 Carabello BA , Paulus WJ. Aortic stenosis . Lancet 2009 ; 373 : 956 – 66 . Google Scholar CrossRef Search ADS PubMed 4 Chandola R , Teoh K , Elhenawy A , Christakis G. Perceval sutureless valve—are sutureless valves here? Curr Cardiol Rev 2015 ; 11 : 220 – 8 . Google Scholar CrossRef Search ADS PubMed 5 Borger MA , Moustafine V , Conradi L , Knosalla C , Richter M , Merk DR et al. A randomized multicenter trial of minimally invasive rapid deployment versus conventional full sternotomy aortic valve replacement . Ann Thorac Surg 2015 ; 99 : 17 – 25 . Google Scholar CrossRef Search ADS PubMed 6 Dalen M , Biancari F , Rubino AS , Santarpino G , Glaser N , De Praetere H et al. Aortic valve replacement through full sternotomy with a stented bioprosthesis versus minimally invasive sternotomy with a sutureless bioprosthesis . Eur J Cardiothorac Surg 2016 ; 49 : 220 – 7 . Google Scholar CrossRef Search ADS PubMed 7 Vola M , Campisi S , Gerbay A , Fuzellier JF , Ayari I , Favre JP et al. Sutureless prostheses and less invasive aortic valve replacement: just an issue of clamping time? Ann Thorac Surg 2015 ; 99 : 1518 – 23 . Google Scholar CrossRef Search ADS PubMed 8 Gilmanov D , Miceli A , Ferrarini M , Farneti P , Murzi M , Solinas M et al. Aortic valve replacement through right anterior minithoracotomy: can sutureless technology improve clinical outcomes? Ann Thorac Surg 2014 ; 98 : 1585 – 92 . Google Scholar CrossRef Search ADS PubMed 9 Konig KC , Wahlers T , Scherner M , Wippermann J. Sutureless perceval aortic valve in comparison with the stented Carpentier-Edwards Perimount aortic valve . J Heart Valve Dis 2014 ; 23 : 253 – 8 . Google Scholar PubMed 10 Al-Sarraf N , Thalib L , Hughes A , Houlihan M , Tolan M , Young V et al. Cross-clamp time is an independent predictor of mortality and morbidity in low- and high-risk cardiac patients . Int J Surg 2011 ; 9 : 104 – 9 . Google Scholar CrossRef Search ADS PubMed 11 Phan K , Xie A , Di Eusanio M , Yan TD. A meta-analysis of minimally invasive versus conventional sternotomy for aortic valve replacement . Ann Thorac Surg 2014 ; 98 : 1499 – 511 . Google Scholar CrossRef Search ADS PubMed 12 Gilmanov D , Bevilacqua S , Murzi M , Cerillo AG , Gasbarri T , Kallushi E et al. Minimally invasive and conventional aortic valve replacement: a propensity score analysis . Ann Thorac Surg 2013 ; 96 : 837 – 43 . Google Scholar CrossRef Search ADS PubMed 13 Furukawa N , Kuss O , Aboud A , Schonbrodt M , Renner A , Hakim Meibodi K et al. Ministernotomy versus conventional sternotomy for aortic valve replacement: matched propensity score analysis of 808 patients . Eur J Cardiothorac Surg 2014 ; 46 : 221 – 6 . Google Scholar CrossRef Search ADS PubMed 14 Food and Drug Administration . Sorin Perceval Sutureless Heart Valve—P150011. https://www.accessdata.fda.gov/cdrh_docs/pdf15/P150011a.pdf (20 June 2017, date last accessed). 15 Lang RM , Badano LP , Mor-Avi V , Afilalo J , Armstrong A , Ernande L et al. Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging . Eur Heart J Cardiovasc Imaging 2015 ; 16 : 233 – 70 . Google Scholar CrossRef Search ADS PubMed 16 Zoghbi WA , Chambers JB , Dumesnil JG , Foster E , Gottdiener JS , Grayburn PA et al. Recommendations for evaluation of prosthetic valves with echocardiography and doppler ultrasound: a report from the American Society of Echocardiography’s Guidelines and Standards Committee and the Task Force on Prosthetic Valves, developed in conjunction with the American College of Cardiology Cardiovascular Imaging Committee, Cardiac Imaging Committee of the American Heart Association, the European Association of Echocardiography, a registered branch of the European Society of Cardiology, the Japanese Society of Echocardiography and the Canadian Society of Echocardiography, endorsed by the American College of Cardiology Foundation, American Heart Association, European Association of Echocardiography, a registered branch of the European Society of Cardiology, the Japanese Society of Echocardiography, and Canadian Society of Echocardiography . J Am Soc Echocardiogr 2009 ; 22 : 975 – 1014 . Google Scholar CrossRef Search ADS PubMed 17 Baumgartner HC , Hung JC-C , Bermejo J , Chambers JB , Edvardsen T , Goldstein S et al. Recommendations on the echocardiographic assessment of aortic valve stenosis: a focused update from the European Association of Cardiovascular Imaging and the American Society of Echocardiography . Eur Heart J Cardiovasc Imaging 2017 ; 18 : 254 – 75 . Google Scholar CrossRef Search ADS PubMed 18 McCann JAS , Robinson JM . Cadriovascular system. In: McCann JAS (ed). Nursing: Deciphering Diagnostic Tests . Philadelphia, Pennsylvania, USA : Lippincott Williams & Wilkins , 2008 : 580 . 19 Buellesfeld L , Gerckens U , Schuler G , Bonan R , Kovac J , Serruys PW et al. 2-year follow-up of patients undergoing transcatheter aortic valve implantation using a self-expanding valve prosthesis . J Am Coll Cardiol 2011 ; 57 : 1650 – 7 . Google Scholar CrossRef Search ADS PubMed 20 Ussia GP , Barbanti M , Petronio AS , Tarantini G , Ettori F , Colombo A et al. Transcatheter aortic valve implantation: 3-year outcomes of self-expanding CoreValve prosthesis . Eur Heart J 2012 ; 33 : 969 – 76 . Google Scholar CrossRef Search ADS PubMed 21 Gessat M , Hopf R , Pollok T , Russ C , Frauenfelder T , Sundermann SH et al. Image-based mechanical analysis of stent deformation: concept and exemplary implementation for aortic valve stents . IEEE Trans Biomed Eng 2014 ; 61 : 4 – 15 . Google Scholar CrossRef Search ADS PubMed 22 Bouhout I , Noly PE , Parisi A , Bouchard D. First case of Perceval S prosthesis early structural valve deterioration: not an easy reoperation . J Thorac Cardiovasc Surg 2016 ; 152 : e71 – 3 . Google Scholar CrossRef Search ADS PubMed 23 Tseng EE , Wisneski A , Azadani AN , Ge L. Engineering perspective on transcatheter aortic valve implantation . Interv Cardiol 2013 ; 5 : 53 – 70 . Google Scholar CrossRef Search ADS 24 Ng AC , Delgado V , van der Kley F , Shanks M , van de Veire NR , Bertini M et al. Comparison of aortic root dimensions and geometries before and after transcatheter aortic valve implantation by 2- and 3-dimensional transesophageal echocardiography and multislice computed tomography . Circ Cardiovasc Imaging 2010 ; 3 : 94 – 102 . Google Scholar CrossRef Search ADS PubMed 25 Egron S , Fujita B , Gullon L , Desiree P , Schmitz-Rode T , Ensminger S et al. Radial force: an underestimated parameter in oversizing transcatheter aortic valve replacement prostheses: in vitro analysis with five commercialized valves . ASAIO J 2017 :1–7, doi:10.1097/MAT0000000000000659. 26 Baert J , Astarci P , Noirhomme P , de Kerchove L. The risk of oversizing with sutureless bioprosthesis in small aortic annulus . J Thorac Cardiovasc Surg 2017 ; 153 : 270 – 2 . Google Scholar CrossRef Search ADS PubMed 27 O'Sullivan KE , Gough A , Segurado R , Barry M , Sugrue D , Hurley J. Is valve choice a significant determinant of paravalular leak post-transcatheter aortic valve implantation? A systematic review and meta-analysis . Eur J Cardiothorac Surg 2014 ; 45 : 826 – 33 . Google Scholar CrossRef Search ADS PubMed 28 Cerillo AG , Amoretti F , Mariani M , Cigala E , Murzi M , Gasbarri T et al. Increased gradients after aortic valve replacement with the perceval valve: the role of oversizing . Ann Thorac Surg 2018 ;S0003-4975:30084-5. © The Author(s) 2018. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Interactive CardioVascular and Thoracic Surgery Oxford University Press

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Abstract

Abstract OBJECTIVES Sutureless aortic valve prostheses are gaining popularity due to the substantial reduction in cross-clamp time. In this study, we report our observations on the cusp-fluttering phenomenon of the Perceval bioprosthesis (LivaNova, London, UK) using a combination of technical and medical perspectives. METHODS Between August 2014 and December 2016, a total of 108 patients (69% women) with a mean age of 78 years had aortic valve replacement using the Perceval bioprosthesis (34 combined procedures). All patients underwent transoesophageal echocardiography (TOE) intraoperatively. TOE was performed postoperatively to detect paravalvular leakage and to measure gradients, acceleration time, Doppler velocity indices (Vmax and LVOT/Vmax AV) and effective orifice area indices. In addition, a TOE examination was performed in 21 patients postoperatively. Data were collected retrospectively from our hospital database. RESULTS The retrospective evaluation of the intraoperative TOE examinations revealed consistent fluttering in all patients with the Perceval bioprosthesis. The echocardiographic postoperative measurements showed a mean effective orifice area index of 0.91 ± 0.12 cm2/m2. The overall mean pressure and peak pressure gradients were in a higher range (13.5 ± 5.1 mmHg and 25.5 ± 8.6 mmHg, respectively), whereas acceleration time (62.8 ± 16.4 ms) and Doppler velocity indices (0.43 ± 0.11) were within the normal range according to the American Society of Echocardiography or european association of echocardiography (EAE) guidelines. The 2-dimensional TOE in Motion Mode (M-Mode) that was performed in patients with elevated lactate dehydrogenase (LDH) levels revealed remarkable fluttering of the cusps of the Perceval bioprosthesis. CONCLUSIONS In our study cohort, we observed the fluttering phenomenon in all patients who received the Perceval bioprosthesis, which was correlated with elevated LDH levels and higher pressure gradients. Perceval bioprosthesis, Fluttering cusps, Sutureless valve INTRODUCTION Because of the steady increase in life expectancy rates across the globe, aortic valve replacements have become more common and are the treatment of choice for severe aortic valve stenosis with left ventricular dysfunction [1, 2]. Cases of severe aortic valve stenosis are fatal if untreated; 75% of patients die within 3 years of symptom onset [3]. More than 20% of patients undergoing conventional aortic valve surgery are older than 80 years [4]. Considering that conventional valve replacements pose challenges for high-risk patients, alternative sutureless valves have become increasingly common for elderly patients with notable comorbidities. The Perceval bioprosthesis (LivaNova, London, UK) is a sutureless valve that is often regarded as a preferable alternative to sutured valves because it reduces the cross-clamp and cardiopulmonary bypass times [5–9]. This is significant because extended cross-clamp time correlates with major postoperative morbidity and mortality in both low- and high-risk patients [10]. Therefore, this alternative valve is especially suitable for high-risk patients who do not meet the conditions for a transcatheter aortic valve implantation (TAVI) procedure and/or patients undergoing combined surgeries. Furthermore, the Perceval bioprosthesis can be implanted via ministernotomy, which reduces surgical trauma and may decrease intensive care unit stay and overall hospital stay [11–13]. The Perceval bioprosthesis has been the subject of extensive multicentre trials in Europe since 2007 [4]. The Perceval bioprosthesis is the most widely used sutureless prosthesis worldwide [4]. Furthermore, in January 2016, the Perceval bioprosthesis was approved by the United States Food and Drug Administration (FDA) [14]. MATERIALS AND METHODS Description of device The Perceval bioprosthesis includes a bovine pericardium secured to a nitinol cage stent (nickel and titanium alloy). The valve is crimped for implantation using a Perceval Dual Collapser device and then expands again to its original shape once placed using the Perceval Dual Holder. After the stent is deployed, the Perceval post-dilation catheter is used to optimize the contact area between the prosthesis and the aortic annulus [4, 14]. Four different valve size options are available for patients with annulus size between 19 mm and 27 mm: small (S) 19–21 mm; medium (M) 22–23 mm; large (L) 24–25 mm and extra large (XL) 26–27 mm. The Perceval bioprosthesis is not suitable for patients with an annular size larger than 27 mm [4]. Technical observation To better understand the mechanical behaviour of the prosthesis, the Perceval bioprosthesis was observed and handled at the Helmholtz Institute (Aachen, Germany) in the laboratory of the Cardiovascular Engineering Department. The bioprosthesis was inspected under a microscope (Keyence VHX-600, Keyence Deutschland GmbH, Neu-Isenburg, Germany), and its computational 3-dimensional design was reconstructed using the software PTC Creo Parametric 3.0 (PTC, Needham, MA, USA) to help with the visualization of its structure. Patients and data collection Between August 2014 and December 2016, data from all patients with aortic valve disease who had aortic valve replacement using the Perceval bioprosthesis, with or without concomitant procedures at our department, were analysed. Informed consent was waived by our ethics committee due to the retrospective nature of the study. Data were retrospectively collected from our clinic’s database and included medical history, echocardiographic assessments, intraoperative data and postoperative outcomes during the 30 postoperative days. Transthoracic and transoesophageal echocardiography assessments As a part of our clinical routine, all patients underwent postoperative transthoracic echocardiography (TTE) within 7 postoperative days in our department. In addition, transoesophageal echocardiography (TOE) was performed intraoperatively in all patients. Echocardiographic assessments were performed according to the guidelines of the European Association of Cardiovascular Imaging (EACVI) and the American Society of Echocardiography (ASE) [15]. TTE measurements performed at rest included transvalvular flow velocity using continuous-wave Doppler scanning and left ventricular outflow tract (LVOT) flow velocity using pulse-wave Doppler scanning. The LVOT diameter was assessed from the parasternal long-axis view. The transvalvular pressure gradient was calculated using the Bernoulli equation with the inclusion of subvalvular velocity and the effective orifice area using the standard continuity equation. The effective orifice area was indexed to the body surface area [effective orifice area index (EOAI)] [16, 17]. In addition to an evaluation of the left ventricular function, the assessment of the aortic valve included the following parameters: EOAI, mean pressure gradient (MPG), peak pressure gradient, flow acceleration time and Doppler velocity index ratio (Vmax LVOT/Vmax AV) [16, 17]. All echocardiographic studies were performed using the Vivid E9 (GE Vingmed Ultrasound AS, Horten, Norway), and the measurements were calculated using EchoPAC version 113 (GE Vingmed Ultrasound AS). In addition, TOE was performed in 21 patients postoperatively within 8 ± 2 postoperative days to rule out paravalvular leakage (PVL) and to assess the valve prosthesis performance relative to increased LDH levels (>500 U/l). Statistical analysis Because of the descriptive nature of our observations, no statistical evaluation was performed. Continuous variables are presented as mean ± standard deviation, and categorical variables are described as absolute numbers and percentages. RESULTS Clinical outcomes Between August 2014 and December 2016, a total of 108 patients (68% women) with a mean age of 77.6 years and a mean body mass index of 28.1 ± 4.5 kg/m2 received aortic valve replacements using the Perceval bioprosthesis (Table 1). Thirty-four patients underwent combined surgeries. Four patients died due to non-valve-related complications. In 2 cases, the Perceval bioprosthesis was removed and replaced with a conventional bioprosthesis due to severe central regurgitation caused by blocked cusps. In the 2 cases of the explanted Perceval valve, the valves were Size M and Size L. The replacement aortic valve was Dokimus® (23 mm) and Trifecta® (25 mm), respectively. Table 1: Patient characteristics Variables Size S Size M Size L Size XL (n = 14) (n = 33) (n = 45) (n = 16) Preoperative data  Age (years), mean ± SD 79 ± 5 77 ± 4 76 ± 4 76 ± 5  Female, n (%) 14 (100) 23 (69.7) 21 (46.7) 2 (12.5)  BMI (kg/m2), mean ± SD 28.1 ± 3.9 27.3 ± 5.4 28.5 ± 4.1 28.6 ± 3.3  KD, n (%) 2 (14.3) 5 (15.5) 4 (8.9) 3 (18.7)  COPD, n (%) 0 7 (21.2) 4 (8.9) 2 (12.5)  IDDM, n (%) 3 (21.4) 10 (30.3) 13 (28.9) 6 (37.5)  HLP, n (%) 6 (42.5) 9 (27.3) 24 (53.3) 7 (43.7)  PAD, n (%) 1 (7.1) 2 (6.1) 4 (8.9) 0  Prior AF, n (%) 3 (27.3) 6 (18.2) 12 (26.7) 9 (56.2)  Prior apoplexy, n (%) 0 3 (9.1) 5 (11.1) 3 (18.7)  EuroSCORE II (%), mean ± SD 2.9 ± 1.1 3.5 ± 1.9 3.4 ± 2.3 3.4 ± 1.6  Log EuroSCORE I, mean ± SD 8.5 ± 5.1 4.8 ± 3.4 6.2 ± 5.1 7.3 ± 5.0  Additive EuroSCORE I (%), mean ± SD 2.2 ± 0.7 1.7 ± 0.6 1.8 ± 0.7 2.0 ± 0.7 Perioperative data  Single AVR, n (%) 12 (85.7) 21 (63.6) 22 (48.9) 6 (37.5)  Combined surgery, n (%) 1 (7.1) 10 (30.3) 23 (55.5) 14 (87.5)  CPB time (min), mean ± SD 95.7 ± 22.3 101.1 ± 48 110.4 ± 42 133.6 ± 48.6  Cross-clamp time (min), mean ± SD 59.7 ± 15.4 64.6 ± 27.5 70.3 ± 24.3 85 ± 24.2 Postoperative data  AV block with PM implantation, n (%) 1 (7.1) 2 (6.1) 3 (6.7) 1 (6.2)  Delirium, n (%) 2 (14.3) 6 (18.2) 4 (8.9) 3 (18.7)  Ischaemic stroke, n (%) 0 1 (3) 2 (4.4) 0  Rethoracotomy due to bleeding, n (%) 0 2 (6.1) 3 (6.7) 2 (12.5)  AF, n (%) 3 (21.4) 11 (33.3) 11 (24.4) 1 (6.2)  Mild PVL, n (%) 3 (21.4) 3 (9.1) 3 (6.7) 1 (6.2)  Moderate PVL, n (%) 0 1 (3) 0 1 (6.2)  Severe PVL, n (%) 0 0 0 0  ICU stay (days), mean ± SD 2.9 ± 2.6 3.6 ± 4.6 5.1 ± 9.4 4.6 ± 8.5 Variables Size S Size M Size L Size XL (n = 14) (n = 33) (n = 45) (n = 16) Preoperative data  Age (years), mean ± SD 79 ± 5 77 ± 4 76 ± 4 76 ± 5  Female, n (%) 14 (100) 23 (69.7) 21 (46.7) 2 (12.5)  BMI (kg/m2), mean ± SD 28.1 ± 3.9 27.3 ± 5.4 28.5 ± 4.1 28.6 ± 3.3  KD, n (%) 2 (14.3) 5 (15.5) 4 (8.9) 3 (18.7)  COPD, n (%) 0 7 (21.2) 4 (8.9) 2 (12.5)  IDDM, n (%) 3 (21.4) 10 (30.3) 13 (28.9) 6 (37.5)  HLP, n (%) 6 (42.5) 9 (27.3) 24 (53.3) 7 (43.7)  PAD, n (%) 1 (7.1) 2 (6.1) 4 (8.9) 0  Prior AF, n (%) 3 (27.3) 6 (18.2) 12 (26.7) 9 (56.2)  Prior apoplexy, n (%) 0 3 (9.1) 5 (11.1) 3 (18.7)  EuroSCORE II (%), mean ± SD 2.9 ± 1.1 3.5 ± 1.9 3.4 ± 2.3 3.4 ± 1.6  Log EuroSCORE I, mean ± SD 8.5 ± 5.1 4.8 ± 3.4 6.2 ± 5.1 7.3 ± 5.0  Additive EuroSCORE I (%), mean ± SD 2.2 ± 0.7 1.7 ± 0.6 1.8 ± 0.7 2.0 ± 0.7 Perioperative data  Single AVR, n (%) 12 (85.7) 21 (63.6) 22 (48.9) 6 (37.5)  Combined surgery, n (%) 1 (7.1) 10 (30.3) 23 (55.5) 14 (87.5)  CPB time (min), mean ± SD 95.7 ± 22.3 101.1 ± 48 110.4 ± 42 133.6 ± 48.6  Cross-clamp time (min), mean ± SD 59.7 ± 15.4 64.6 ± 27.5 70.3 ± 24.3 85 ± 24.2 Postoperative data  AV block with PM implantation, n (%) 1 (7.1) 2 (6.1) 3 (6.7) 1 (6.2)  Delirium, n (%) 2 (14.3) 6 (18.2) 4 (8.9) 3 (18.7)  Ischaemic stroke, n (%) 0 1 (3) 2 (4.4) 0  Rethoracotomy due to bleeding, n (%) 0 2 (6.1) 3 (6.7) 2 (12.5)  AF, n (%) 3 (21.4) 11 (33.3) 11 (24.4) 1 (6.2)  Mild PVL, n (%) 3 (21.4) 3 (9.1) 3 (6.7) 1 (6.2)  Moderate PVL, n (%) 0 1 (3) 0 1 (6.2)  Severe PVL, n (%) 0 0 0 0  ICU stay (days), mean ± SD 2.9 ± 2.6 3.6 ± 4.6 5.1 ± 9.4 4.6 ± 8.5 AF: atrial fibrillation; AV: atrioventricular; AVR: aortic valve replacement; BMI: body mass index; COPD: chronic obstructive pulmonary disease; CPB: cardiopulmonary bypass; HLP: hyperlipoproteinaemia; ICU: intensive care unit; IDDM: insulin-dependent diabetes mellitus; KD: kidney disease; PAD: peripheral artery disease; PM: Pacemaker; PVL: paravalvular leak; SD: standard deviation. Table 1: Patient characteristics Variables Size S Size M Size L Size XL (n = 14) (n = 33) (n = 45) (n = 16) Preoperative data  Age (years), mean ± SD 79 ± 5 77 ± 4 76 ± 4 76 ± 5  Female, n (%) 14 (100) 23 (69.7) 21 (46.7) 2 (12.5)  BMI (kg/m2), mean ± SD 28.1 ± 3.9 27.3 ± 5.4 28.5 ± 4.1 28.6 ± 3.3  KD, n (%) 2 (14.3) 5 (15.5) 4 (8.9) 3 (18.7)  COPD, n (%) 0 7 (21.2) 4 (8.9) 2 (12.5)  IDDM, n (%) 3 (21.4) 10 (30.3) 13 (28.9) 6 (37.5)  HLP, n (%) 6 (42.5) 9 (27.3) 24 (53.3) 7 (43.7)  PAD, n (%) 1 (7.1) 2 (6.1) 4 (8.9) 0  Prior AF, n (%) 3 (27.3) 6 (18.2) 12 (26.7) 9 (56.2)  Prior apoplexy, n (%) 0 3 (9.1) 5 (11.1) 3 (18.7)  EuroSCORE II (%), mean ± SD 2.9 ± 1.1 3.5 ± 1.9 3.4 ± 2.3 3.4 ± 1.6  Log EuroSCORE I, mean ± SD 8.5 ± 5.1 4.8 ± 3.4 6.2 ± 5.1 7.3 ± 5.0  Additive EuroSCORE I (%), mean ± SD 2.2 ± 0.7 1.7 ± 0.6 1.8 ± 0.7 2.0 ± 0.7 Perioperative data  Single AVR, n (%) 12 (85.7) 21 (63.6) 22 (48.9) 6 (37.5)  Combined surgery, n (%) 1 (7.1) 10 (30.3) 23 (55.5) 14 (87.5)  CPB time (min), mean ± SD 95.7 ± 22.3 101.1 ± 48 110.4 ± 42 133.6 ± 48.6  Cross-clamp time (min), mean ± SD 59.7 ± 15.4 64.6 ± 27.5 70.3 ± 24.3 85 ± 24.2 Postoperative data  AV block with PM implantation, n (%) 1 (7.1) 2 (6.1) 3 (6.7) 1 (6.2)  Delirium, n (%) 2 (14.3) 6 (18.2) 4 (8.9) 3 (18.7)  Ischaemic stroke, n (%) 0 1 (3) 2 (4.4) 0  Rethoracotomy due to bleeding, n (%) 0 2 (6.1) 3 (6.7) 2 (12.5)  AF, n (%) 3 (21.4) 11 (33.3) 11 (24.4) 1 (6.2)  Mild PVL, n (%) 3 (21.4) 3 (9.1) 3 (6.7) 1 (6.2)  Moderate PVL, n (%) 0 1 (3) 0 1 (6.2)  Severe PVL, n (%) 0 0 0 0  ICU stay (days), mean ± SD 2.9 ± 2.6 3.6 ± 4.6 5.1 ± 9.4 4.6 ± 8.5 Variables Size S Size M Size L Size XL (n = 14) (n = 33) (n = 45) (n = 16) Preoperative data  Age (years), mean ± SD 79 ± 5 77 ± 4 76 ± 4 76 ± 5  Female, n (%) 14 (100) 23 (69.7) 21 (46.7) 2 (12.5)  BMI (kg/m2), mean ± SD 28.1 ± 3.9 27.3 ± 5.4 28.5 ± 4.1 28.6 ± 3.3  KD, n (%) 2 (14.3) 5 (15.5) 4 (8.9) 3 (18.7)  COPD, n (%) 0 7 (21.2) 4 (8.9) 2 (12.5)  IDDM, n (%) 3 (21.4) 10 (30.3) 13 (28.9) 6 (37.5)  HLP, n (%) 6 (42.5) 9 (27.3) 24 (53.3) 7 (43.7)  PAD, n (%) 1 (7.1) 2 (6.1) 4 (8.9) 0  Prior AF, n (%) 3 (27.3) 6 (18.2) 12 (26.7) 9 (56.2)  Prior apoplexy, n (%) 0 3 (9.1) 5 (11.1) 3 (18.7)  EuroSCORE II (%), mean ± SD 2.9 ± 1.1 3.5 ± 1.9 3.4 ± 2.3 3.4 ± 1.6  Log EuroSCORE I, mean ± SD 8.5 ± 5.1 4.8 ± 3.4 6.2 ± 5.1 7.3 ± 5.0  Additive EuroSCORE I (%), mean ± SD 2.2 ± 0.7 1.7 ± 0.6 1.8 ± 0.7 2.0 ± 0.7 Perioperative data  Single AVR, n (%) 12 (85.7) 21 (63.6) 22 (48.9) 6 (37.5)  Combined surgery, n (%) 1 (7.1) 10 (30.3) 23 (55.5) 14 (87.5)  CPB time (min), mean ± SD 95.7 ± 22.3 101.1 ± 48 110.4 ± 42 133.6 ± 48.6  Cross-clamp time (min), mean ± SD 59.7 ± 15.4 64.6 ± 27.5 70.3 ± 24.3 85 ± 24.2 Postoperative data  AV block with PM implantation, n (%) 1 (7.1) 2 (6.1) 3 (6.7) 1 (6.2)  Delirium, n (%) 2 (14.3) 6 (18.2) 4 (8.9) 3 (18.7)  Ischaemic stroke, n (%) 0 1 (3) 2 (4.4) 0  Rethoracotomy due to bleeding, n (%) 0 2 (6.1) 3 (6.7) 2 (12.5)  AF, n (%) 3 (21.4) 11 (33.3) 11 (24.4) 1 (6.2)  Mild PVL, n (%) 3 (21.4) 3 (9.1) 3 (6.7) 1 (6.2)  Moderate PVL, n (%) 0 1 (3) 0 1 (6.2)  Severe PVL, n (%) 0 0 0 0  ICU stay (days), mean ± SD 2.9 ± 2.6 3.6 ± 4.6 5.1 ± 9.4 4.6 ± 8.5 AF: atrial fibrillation; AV: atrioventricular; AVR: aortic valve replacement; BMI: body mass index; COPD: chronic obstructive pulmonary disease; CPB: cardiopulmonary bypass; HLP: hyperlipoproteinaemia; ICU: intensive care unit; IDDM: insulin-dependent diabetes mellitus; KD: kidney disease; PAD: peripheral artery disease; PM: Pacemaker; PVL: paravalvular leak; SD: standard deviation. In the 3rd case, the patient returned to cardiology department after 6 months with severe stenosis due to a blocked cusp [15] (Video 1 demonstrates the blockage of the valve leaflet in the position of right coronary cusp with TOE). The patient refused the reoperation and the secondary option of a valve in valve procedure (TAVI). The current condition of this patient is unknown. In both cases, the valve was easily explanted. Upon closer observation of the explanted valves, it was clear that the leaflets and the stents appeared normal and not deformed. Echocardiographic findings All patients underwent early postoperative echo studies. TTE was performed prior to discharge to detect PVL and measure gradients, acceleration time, ejection time (ET), Doppler velocity indices (Vmax LVOT/Vmax AV) and EOAI to the body surface area. The data were collected retrospectively from our hospital database (Table 2). Table 2: Echocardiographic analysis Parameters Size S (n = 14) Size M (n = 33) Size L (n = 45) Size XL (n = 16) MPG (mmHg) 13.4 ± 4.8 14.8 ± 6.1 12.4 ± 3.7 15.4 ± 6.4 PPG (mmHg) 24.8 ± 8.9 26.9 ± 9.7 23.5 ± 6.1 29.4 ± 10.2 EOAI (mm2) 0.65 ± 0.21 0.58 ± 0.17 0.73 ± 0.23 0.79 ± 0.22 AT (ms) 63.9 ± 16.7 62.3 ± 13.5 64.6 ± 14.3 57.4 ± 22.6 ET (ms) 241.7 ± 37.4 261.1 ± 32.4 260.4 ± 41.5 253.6 ± 26.6 DVI 0.47 ± 0.12 0.42 ± 0.10 0.44 ± 0.12 0.40 ± 0.10 Parameters Size S (n = 14) Size M (n = 33) Size L (n = 45) Size XL (n = 16) MPG (mmHg) 13.4 ± 4.8 14.8 ± 6.1 12.4 ± 3.7 15.4 ± 6.4 PPG (mmHg) 24.8 ± 8.9 26.9 ± 9.7 23.5 ± 6.1 29.4 ± 10.2 EOAI (mm2) 0.65 ± 0.21 0.58 ± 0.17 0.73 ± 0.23 0.79 ± 0.22 AT (ms) 63.9 ± 16.7 62.3 ± 13.5 64.6 ± 14.3 57.4 ± 22.6 ET (ms) 241.7 ± 37.4 261.1 ± 32.4 260.4 ± 41.5 253.6 ± 26.6 DVI 0.47 ± 0.12 0.42 ± 0.10 0.44 ± 0.12 0.40 ± 0.10 Values are presented as mean ± standard deviation. AT: acceleration time; DVI: Doppler velocity indices; EOAI: effective orifice area index; ET: ejection time; MPG: mean pressure gradient; PPG: peak pressure gradient. Table 2: Echocardiographic analysis Parameters Size S (n = 14) Size M (n = 33) Size L (n = 45) Size XL (n = 16) MPG (mmHg) 13.4 ± 4.8 14.8 ± 6.1 12.4 ± 3.7 15.4 ± 6.4 PPG (mmHg) 24.8 ± 8.9 26.9 ± 9.7 23.5 ± 6.1 29.4 ± 10.2 EOAI (mm2) 0.65 ± 0.21 0.58 ± 0.17 0.73 ± 0.23 0.79 ± 0.22 AT (ms) 63.9 ± 16.7 62.3 ± 13.5 64.6 ± 14.3 57.4 ± 22.6 ET (ms) 241.7 ± 37.4 261.1 ± 32.4 260.4 ± 41.5 253.6 ± 26.6 DVI 0.47 ± 0.12 0.42 ± 0.10 0.44 ± 0.12 0.40 ± 0.10 Parameters Size S (n = 14) Size M (n = 33) Size L (n = 45) Size XL (n = 16) MPG (mmHg) 13.4 ± 4.8 14.8 ± 6.1 12.4 ± 3.7 15.4 ± 6.4 PPG (mmHg) 24.8 ± 8.9 26.9 ± 9.7 23.5 ± 6.1 29.4 ± 10.2 EOAI (mm2) 0.65 ± 0.21 0.58 ± 0.17 0.73 ± 0.23 0.79 ± 0.22 AT (ms) 63.9 ± 16.7 62.3 ± 13.5 64.6 ± 14.3 57.4 ± 22.6 ET (ms) 241.7 ± 37.4 261.1 ± 32.4 260.4 ± 41.5 253.6 ± 26.6 DVI 0.47 ± 0.12 0.42 ± 0.10 0.44 ± 0.12 0.40 ± 0.10 Values are presented as mean ± standard deviation. AT: acceleration time; DVI: Doppler velocity indices; EOAI: effective orifice area index; ET: ejection time; MPG: mean pressure gradient; PPG: peak pressure gradient. We performed TOE in 21 patients to rule out PVLs and to assess valve prosthesis performance relative to increased MPG and LDH levels (>500 U/l). TOE in M-Mode led to the observation of the cusp-fluttering phenomenon. The repeated review of postoperative TTE did not reveal fluttering due to insufficient image quality. The review of intraoperative TOE, however, did reveal fluttering in all patients (78) whose TOE results were saved in the database. Fluttering phenomenon TOE in M-Mode led to the observation of the cusp-fluttering phenomenon. Usually, during the ventricular systole, the separated cusps of the aortic valve appear in box form in M-Mode. They remain open throughout the systole and sometimes demonstrate a fine fluttering motion [18]. The fluttering cusp phenomenon is defined by the abnormal behaviour of the Perceval cusps during the systole. During ejection, the cusps’ movements vary wildly between the edge and the base, often nearly coming to a complete close. As an initial point of reference, Fig. 1 depicts the normal performance of a biological aortic valve prosthesis (Carpentier-Edwards Perimount, Fig. 1A) and 5 additional examples of the remarkable fluttering of the Perceval bioprosthesis (Fig. 1B–F). Throughout the systole (Fig. 1A), both the RCC and ACC cusps are continually open in a parallel formation, not disturbing the laminar blood flow. During the entire systole phase, the effective orifice area remains constant. Compared to the normal cusp behaviour presented in Fig. 1A, the proximity of the Perceval bioprosthesis cusp edges to each other during the systole is easily observed, which could potentially disturb the regular blood flow of the patient. In some cases, the oscillation reaches a frequency of 15 Hz or approximately 1000 flutters/min (Fig. 1B). Planimetric measurements of the orifice area pose a challenge given the abnormal mobility of the valve cusps during the systole. The turbulence and aliasing effect reveal the functional stenosis of the valve as shown in Fig. 1E and F. The intermittent fluttering of the cusps results in irregular high velocity output. Figure 1: View largeDownload slide Contrasting valve cusp behaviour. (A) M-mode in the parasternal long axis showing normal bioprosthesis performance (Carpentier-Edwards Perimount®). (B–D) The fluttering cusp phenomenon that is unique to the Perceval bioprosthesis. The fluttering is also present at a lower frequency (C and D above). This cusp-fluttering phenomenon is also clearly visible in colour (E) and continuous Doppler (F). Figure 1: View largeDownload slide Contrasting valve cusp behaviour. (A) M-mode in the parasternal long axis showing normal bioprosthesis performance (Carpentier-Edwards Perimount®). (B–D) The fluttering cusp phenomenon that is unique to the Perceval bioprosthesis. The fluttering is also present at a lower frequency (C and D above). This cusp-fluttering phenomenon is also clearly visible in colour (E) and continuous Doppler (F). Observations from the technical examination of the Perceval bioprosthesis Several structural features distinguish the Perceval bioprosthesis from other widely used TAVI Nitinol prostheses. First, its frame is higher than comparable TAVI Nitinol prostheses [19, 20]. Second, the cusps’ commissures are sutured along 3 long vertical struts. This is a unique feature in the prosthesis valve design (Fig. 2) and contrasts with the continuous diamond structure and suturing pattern of comparable TAVI Nitinol prostheses [21]. Third, the Perceval frame is very flexible (radial force tests show that the Perceval stent is more flexible than other widely used stents) [20, 21]. Figure 2: View largeDownload slide The Perceval stent structure. Figure 2: View largeDownload slide The Perceval stent structure. Figure 2 shows an in-house 3-dimensional design reproduction of the Perceval stent following inspection of the frame under a microscope. Mainly, it consists of top and bottom ring structures that are connected by 3 thick struts (blue dotted line) and 2 thinner curved branches between each strut. The prosthetic cusps are sutured, and the commissures of the cusps are fixed to the 3 main struts (blue dotted lines). Considering the unique design of the Perceval stent and the way the cusps are attached to the stent, it appears that a small external deformation can lead to an abnormally stretched position of 1 or 2 cusps. Increased deformation can eventually lead to the full blockage of 1 or 2 cusps (depending on the stent orientation) [22]. We demonstrate an example of a blocked cusp of the Perceval bioprosthesis in Video 1. In Fig. 3, it is possible to observe that the slight ovalization of the prosthesis directly translates to a greater distance between Commissures C1 and C2 and tenses cusp L1. Figure 3: View largeDownload slide Ovalization of the stent. The slight ovalization of the prosthesis directly translates to a greater distance between Commissures C1 and C2 and tenses cusp L1. Figure 3: View largeDownload slide Ovalization of the stent. The slight ovalization of the prosthesis directly translates to a greater distance between Commissures C1 and C2 and tenses cusp L1. Video 1 Blockage of a Perceval bioprosthesis cusp. Transoesophageal echocardiography, 120°, blocked right coronary cusp of the Perceval bioprosthesis. Video 1 Blockage of a Perceval bioprosthesis cusp. Transoesophageal echocardiography, 120°, blocked right coronary cusp of the Perceval bioprosthesis. Close Depending on the orientation of the prosthesis deformation, 1 or 2 leaflets can be abnormally stretched, as demonstrated in Fig. 3. The fluttering of the cusp observed during echocardiographic examinations can be explained using an abnormally stretched cusp. The hypothesis that a Perceval bioprosthesis implanted in a patient can present 1 or 2 stretched cusps is verified by several aspects that are all specific to the Perceval bioprosthesis: The Perceval stent is very flexible and, therefore, prone to small deformation or ovalization in patients’ aortic anatomies. Comparably, computed tomography scan images show that widely used TAVI Nitinol prostheses are rarely perfectly circular [23, 24] in patients, and radial force tests show that the Perceval Nitinol stent is even more flexible than other widely used TAVI Nitinol stents [25]. Given the stent design (the 3 long vertical struts) and suturing pattern (the leaflet commissures attached to the long struts), deformation or ovalization of the stent translates directly into an increased distance between opposite commissures, with 1 or 2 stretched cusps depending on the valve orientation. DISCUSSION The fluttering cusp phenomenon exhibited by the Perceval bioprosthesis post-implantation was initially discovered during a transoesophageal echocardiographic examination in M-Mode. Observing the behaviour of the cusps in a 1-dimensional format revealed that there were abnormalities in the cusp dynamics. The irregular movements of the cusps can be best described as distinctly ‘fluttering’ throughout the systole, which is not present to the same extent in conventional sutured valves. A certain degree of fluttering is present naturally in most prosthetic valve cusps for a short instant before they are completely open and when they are in the open position, but it is not as extreme as is in the case of the Perceval bioprosthesis [18]. All patients had a low EOAI, but not all patients who exhibited the fluttering phenomenon had a high MPG. A high MPG was found only in 36% of patients, and in all patients, high LDH levels were recorded. Because of the distinct fluttering of the Perceval valve cusps throughout the systole, accurate planimetric measurements of the orifice area are relatively challenging. This impedes the accurate examination of valve performance and the interpretation of results when using traditional echocardiography parameters. One explanation for this phenomenon may be the design of the Perceval stent, which is very flexible and, therefore, prone to slight deformation or ovalization in patients’ aortic anatomies. Oversizing is an unlikely cause of the fluttering phenomenon because the Perceval-delivered sizing device was used in all cases throughout the study. Furthermore, in 2016, a cardiac surgeon hired by LivaNova proctored the Perceval implantation operation in more than 10 patients at the University Hospital Aachen Cardiac Surgery department. The fluttering phenomenon was present postoperatively in all these patients. Moreover, it is well documented that oversizing can lead to paravalvular aortic regurgitation, whereas oversizing to a higher degree may lead to a non-fully expanded prosthesis, central aortic regurgitation [25–27], acute valve failure and a very high transvalvular gradient [28]. In our observational study of the fluttering phenomenon, we did not encounter any relevant PVLs or central regurgitation. We observed higher gradients in patients with Perceval valves when compared to those with conventional valves, but the valves with gradients in a normal range showed remarkable fluttering, which is also an evidence against the notion that oversizing causes the fluttering. Our radial force test shows that the Perceval stent is very flexible, meaning that any small force leads to minor deformations of the stent during the heart cycle. These small deformations of the stent during the systole lead to the flutter phenomenon. Even appropriately sized Perceval prostheses are easily deformed from external forces during the systole due to the very low radial forces, which then causes the fluttering phenomenon. For these reasons, it can be deduced that the cusp-fluttering phenomenon is due to the problematic design of the Perceval stent and not simply a result of oversizing. A high degree of oversizing (non-fully expanded valve) leads to cusp folding and subsequently, cusp blockage. This was observed through transoesophageal echocardiographic examination which showed cusp thickening. The impact of the different degrees of oversizing on their performance of the valve should be studied further in the future. Further in vitro studies are required to analyse the fluttering phenomenon of the Perceval bioprosthesis, and long-term follow-up results are necessary to evaluate whether this fluttering phenomenon will result in early damage to the cusps. Continuous critical evaluations of medical practices and devices, including frequent and impartial multidisciplinary studies, are necessary to keep pace with innovations in the medical technology industry. In this way, medical professionals can avoid the pitfalls of prioritizing private interests over the long-term well-being of their patients. Limitations Although our data are limited by the usual shortcomings of a retrospective observational study, the uniform presentation of the phenomenon throughout all patients prevents a different study design. The major drawback is the lack of long-term data, which will be collected in the near future. Conflict of interest: none declared. REFERENCES 1 Iung B , Baron G , Butchart EG , Delahaye F , Gohlke-Barwolf C , Levang OW et al. A prospective survey of patients with valvular heart disease in Europe: the Euro Heart Survey on Valvular Heart Disease . Eur Heart J 2003 ; 24 : 1231 – 43 . Google Scholar CrossRef Search ADS PubMed 2 Funkat A , Beckmann A , Lewandowski J , Frie M , Ernst M , Schiller W et al. Cardiac surgery in Germany during 2012: a report on behalf of the German Society for Thoracic and Cardiovascular Surgery . Thorac Cardiovasc Surg 2014 ; 62 : 380 – 17 . Google Scholar CrossRef Search ADS PubMed 3 Carabello BA , Paulus WJ. Aortic stenosis . Lancet 2009 ; 373 : 956 – 66 . Google Scholar CrossRef Search ADS PubMed 4 Chandola R , Teoh K , Elhenawy A , Christakis G. Perceval sutureless valve—are sutureless valves here? Curr Cardiol Rev 2015 ; 11 : 220 – 8 . Google Scholar CrossRef Search ADS PubMed 5 Borger MA , Moustafine V , Conradi L , Knosalla C , Richter M , Merk DR et al. A randomized multicenter trial of minimally invasive rapid deployment versus conventional full sternotomy aortic valve replacement . Ann Thorac Surg 2015 ; 99 : 17 – 25 . Google Scholar CrossRef Search ADS PubMed 6 Dalen M , Biancari F , Rubino AS , Santarpino G , Glaser N , De Praetere H et al. Aortic valve replacement through full sternotomy with a stented bioprosthesis versus minimally invasive sternotomy with a sutureless bioprosthesis . Eur J Cardiothorac Surg 2016 ; 49 : 220 – 7 . Google Scholar CrossRef Search ADS PubMed 7 Vola M , Campisi S , Gerbay A , Fuzellier JF , Ayari I , Favre JP et al. Sutureless prostheses and less invasive aortic valve replacement: just an issue of clamping time? Ann Thorac Surg 2015 ; 99 : 1518 – 23 . Google Scholar CrossRef Search ADS PubMed 8 Gilmanov D , Miceli A , Ferrarini M , Farneti P , Murzi M , Solinas M et al. Aortic valve replacement through right anterior minithoracotomy: can sutureless technology improve clinical outcomes? Ann Thorac Surg 2014 ; 98 : 1585 – 92 . Google Scholar CrossRef Search ADS PubMed 9 Konig KC , Wahlers T , Scherner M , Wippermann J. Sutureless perceval aortic valve in comparison with the stented Carpentier-Edwards Perimount aortic valve . J Heart Valve Dis 2014 ; 23 : 253 – 8 . Google Scholar PubMed 10 Al-Sarraf N , Thalib L , Hughes A , Houlihan M , Tolan M , Young V et al. Cross-clamp time is an independent predictor of mortality and morbidity in low- and high-risk cardiac patients . Int J Surg 2011 ; 9 : 104 – 9 . Google Scholar CrossRef Search ADS PubMed 11 Phan K , Xie A , Di Eusanio M , Yan TD. A meta-analysis of minimally invasive versus conventional sternotomy for aortic valve replacement . Ann Thorac Surg 2014 ; 98 : 1499 – 511 . Google Scholar CrossRef Search ADS PubMed 12 Gilmanov D , Bevilacqua S , Murzi M , Cerillo AG , Gasbarri T , Kallushi E et al. Minimally invasive and conventional aortic valve replacement: a propensity score analysis . Ann Thorac Surg 2013 ; 96 : 837 – 43 . Google Scholar CrossRef Search ADS PubMed 13 Furukawa N , Kuss O , Aboud A , Schonbrodt M , Renner A , Hakim Meibodi K et al. Ministernotomy versus conventional sternotomy for aortic valve replacement: matched propensity score analysis of 808 patients . Eur J Cardiothorac Surg 2014 ; 46 : 221 – 6 . Google Scholar CrossRef Search ADS PubMed 14 Food and Drug Administration . Sorin Perceval Sutureless Heart Valve—P150011. https://www.accessdata.fda.gov/cdrh_docs/pdf15/P150011a.pdf (20 June 2017, date last accessed). 15 Lang RM , Badano LP , Mor-Avi V , Afilalo J , Armstrong A , Ernande L et al. Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging . Eur Heart J Cardiovasc Imaging 2015 ; 16 : 233 – 70 . Google Scholar CrossRef Search ADS PubMed 16 Zoghbi WA , Chambers JB , Dumesnil JG , Foster E , Gottdiener JS , Grayburn PA et al. Recommendations for evaluation of prosthetic valves with echocardiography and doppler ultrasound: a report from the American Society of Echocardiography’s Guidelines and Standards Committee and the Task Force on Prosthetic Valves, developed in conjunction with the American College of Cardiology Cardiovascular Imaging Committee, Cardiac Imaging Committee of the American Heart Association, the European Association of Echocardiography, a registered branch of the European Society of Cardiology, the Japanese Society of Echocardiography and the Canadian Society of Echocardiography, endorsed by the American College of Cardiology Foundation, American Heart Association, European Association of Echocardiography, a registered branch of the European Society of Cardiology, the Japanese Society of Echocardiography, and Canadian Society of Echocardiography . J Am Soc Echocardiogr 2009 ; 22 : 975 – 1014 . Google Scholar CrossRef Search ADS PubMed 17 Baumgartner HC , Hung JC-C , Bermejo J , Chambers JB , Edvardsen T , Goldstein S et al. Recommendations on the echocardiographic assessment of aortic valve stenosis: a focused update from the European Association of Cardiovascular Imaging and the American Society of Echocardiography . Eur Heart J Cardiovasc Imaging 2017 ; 18 : 254 – 75 . Google Scholar CrossRef Search ADS PubMed 18 McCann JAS , Robinson JM . Cadriovascular system. In: McCann JAS (ed). Nursing: Deciphering Diagnostic Tests . Philadelphia, Pennsylvania, USA : Lippincott Williams & Wilkins , 2008 : 580 . 19 Buellesfeld L , Gerckens U , Schuler G , Bonan R , Kovac J , Serruys PW et al. 2-year follow-up of patients undergoing transcatheter aortic valve implantation using a self-expanding valve prosthesis . J Am Coll Cardiol 2011 ; 57 : 1650 – 7 . Google Scholar CrossRef Search ADS PubMed 20 Ussia GP , Barbanti M , Petronio AS , Tarantini G , Ettori F , Colombo A et al. Transcatheter aortic valve implantation: 3-year outcomes of self-expanding CoreValve prosthesis . Eur Heart J 2012 ; 33 : 969 – 76 . Google Scholar CrossRef Search ADS PubMed 21 Gessat M , Hopf R , Pollok T , Russ C , Frauenfelder T , Sundermann SH et al. Image-based mechanical analysis of stent deformation: concept and exemplary implementation for aortic valve stents . IEEE Trans Biomed Eng 2014 ; 61 : 4 – 15 . Google Scholar CrossRef Search ADS PubMed 22 Bouhout I , Noly PE , Parisi A , Bouchard D. First case of Perceval S prosthesis early structural valve deterioration: not an easy reoperation . J Thorac Cardiovasc Surg 2016 ; 152 : e71 – 3 . Google Scholar CrossRef Search ADS PubMed 23 Tseng EE , Wisneski A , Azadani AN , Ge L. Engineering perspective on transcatheter aortic valve implantation . Interv Cardiol 2013 ; 5 : 53 – 70 . Google Scholar CrossRef Search ADS 24 Ng AC , Delgado V , van der Kley F , Shanks M , van de Veire NR , Bertini M et al. Comparison of aortic root dimensions and geometries before and after transcatheter aortic valve implantation by 2- and 3-dimensional transesophageal echocardiography and multislice computed tomography . Circ Cardiovasc Imaging 2010 ; 3 : 94 – 102 . Google Scholar CrossRef Search ADS PubMed 25 Egron S , Fujita B , Gullon L , Desiree P , Schmitz-Rode T , Ensminger S et al. Radial force: an underestimated parameter in oversizing transcatheter aortic valve replacement prostheses: in vitro analysis with five commercialized valves . ASAIO J 2017 :1–7, doi:10.1097/MAT0000000000000659. 26 Baert J , Astarci P , Noirhomme P , de Kerchove L. The risk of oversizing with sutureless bioprosthesis in small aortic annulus . J Thorac Cardiovasc Surg 2017 ; 153 : 270 – 2 . Google Scholar CrossRef Search ADS PubMed 27 O'Sullivan KE , Gough A , Segurado R , Barry M , Sugrue D , Hurley J. Is valve choice a significant determinant of paravalular leak post-transcatheter aortic valve implantation? A systematic review and meta-analysis . Eur J Cardiothorac Surg 2014 ; 45 : 826 – 33 . Google Scholar CrossRef Search ADS PubMed 28 Cerillo AG , Amoretti F , Mariani M , Cigala E , Murzi M , Gasbarri T et al. Increased gradients after aortic valve replacement with the perceval valve: the role of oversizing . Ann Thorac Surg 2018 ;S0003-4975:30084-5. © The Author(s) 2018. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)

Journal

Interactive CardioVascular and Thoracic SurgeryOxford University Press

Published: May 17, 2018

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