Femoro-Femoral Partial Bypass in the
Treatment of Thoracoabdominal Aneurysms
Michael A. Coady and R. Scott Mitchell
This article describes our rationale for the use of femoro-femoral bypass as a primary modality for
perfusion in the repair of thoracoabdominal aortic aneurysms at Stanford University School of Medi-
cine. Benefits and limitations of this method are discussed and compared with other described
techniques.
© 2003 Elsevier Inc. All rights reserved.
Key words: Thoracoabdominal aneurysm, cardiopulmonary bypass.
A
neurysms of the descending and thoracoab-
dominal aorta span the spectrum from dis-
crete localized involvement to more extensive
pathology encompassing the entire thoracoab-
dominal aorta, from the subclavian origin to the
iliac bifurcation. The surgical approach varies
depending on the extent of associated aortic in-
volvement. Several techniques for distal aortic
perfusion have evolved to facilitate replacement
of the descending and thoracoabdominal aorta.
The primary goal involves an expeditious and
secure replacement of the aneurysm while avoid-
ing ischemic injury to abdominal viscera, spinal
cord, and lower extremities.
The simple clamping of the aorta for proximal
control during repair of descending and thoraco-
abdominal aneurysms leads to profound homeo-
static disturbances in nearly all organ systems in
the body. Acute changes include a severe increase
in peripheral vascular resistance and afterload.
This is coupled with proximal hypertension, in-
creased ventricular strain and stroke work, pul-
monary congestion, and a substantial increase in
cerebral spinal fluid pressure.
1
A significant sym-
pathetic discharge occurs with increases in epi-
nephrine and norepinephrine, as well as in-
creases in plasma levels of lactic acid and renin.
Depending on the site and duration of cross-
clamping, as much as 2/3 of the body may become
acutely ischemic, leading to electrolyte abnor-
malities, profound acidosis, and the potential for
visceral, renal, and spinal cord injury. The release
of the aortic clamp poses similar risks, with an
acute decrease in preload and afterload, reperfu-
sion injury, washout of ischemic metabolites, and
declamping-associated shock.
Simple clamping, absent distal aortic perfu-
sion, results in severe hypoperfusion of abdomi-
nal viscera, lower extremities, and the lower tho-
racic and lumbar spinal cord and is thus limited
to a “tolerable ischemic time,” preferably less
than 35 to 45 minutes. Therefore, clamping alone
remains an undesirable technique for aneurysm
resection and has been largely supplanted by ad-
juncts allowing distal aortic perfusion. In an ef-
fort to address issues related to the pathophysi-
ologic changes on both sides of the proximal
aortic clamp, several techniques for distal aortic
perfusion during thoracic aortic aneurysm sur-
gery have evolved (Table 1).
Extracorporeal perfusion techniques are used
to facilitate repair as well as provide protection
against the effects of simple cross-clamping. Dis-
tal aortic perfusion during descending thoracic
and thoracoabdominal aneurysm repair provides
perfusion to the renals, mesenteric, and spinal
cord regions, which serves to minimize ischemic
complications compared with simple cross-clamp-
ing and passive shunts. These adjunctive mea-
sures are used with the intent to prevent, or at
least attenuate, some of the known complications
associated with operative intervention. Options
for distal aortic perfusion techniques include left
atrial-femoral bypass, femoro-femoral cardiopul-
From the Department of Cardiothoracic Surgery, Stanford Univer-
sity School of Medicine, Falk Cardiovascular Research Center, Palo
Alto, CA.
Address reprint requests to R. Scott Mitchell, MD, Professor of
Cardiovascular Surgery, Department of Cardiothoracic Surgery, Stan-
ford University School of Medicine, Falk Cardiovascular Research
Center, Palo Alto, CA 94305-5407.
© 2003 Elsevier Inc. All rights reserved.
1043-0679/03/1504-0004$30.00/0
doi:10.1053/S1043-0679(03)00089-3
340
Seminars in Thoracic and Cardiovascular Surgery, Vol 15, No 4 (October), 2003: pp 340-344