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III. Treatment of Thoracic Degenerative Aortic Aneurysms
Fig. 12.5. Newly designed filter device
Fig. 12.7. Macroscopic view of embolic particles captured by fil-
ter devices
Fig. 12.6. Fluoroscopic image after filter deployment in the car-
otid arteries
12.2.6 Patients and Anatomic Criteria
for Endovascular Repair
Between November 1995 and March 2002, the procedure
was attempted in 48 patients with aortic arch aneurysms. The mean age of the patients was 68 years
(range, 21±87), with a male-to-female ratio of 5:1. Etiologies included atherosclerosis in 26 patients, chronic
aortic dissection in 15 patients, and posttraumatic or
false aneurysm in seven patients. Because of the experimental nature of this procedure, it was mainly performed for high-risk surgical patients. The anatomic
criteria are as follows:
1. For placement of a single-branched or a double
branched stent-graft, both the proximal and the distal landing zones should be at least 1 cm long.
2. If a single-branched stent-graft is to be employed,
ideally, the front part of the proximal landing zone
(the segment between the origin of the left subclavian artery and the left carotid artery) and the back
part of the proximal landing zone (the segment between the origin of the left subclavian artery and the
proximal aspect of the aneurysm) should each be
more than 5 mm in length.
3. For placement of a triple-branched stent-graft, a
proximal landing zone at least 3-cm long and a distal
landing zone at least 1 cm long must be present.
4. The caliber of the normal artery selected for sidearm
implantation must be 8 mm or more in diameter.
K. Inoue et al. Chapter 12 Management of the Horizontal Aorta with the Inoue Branched Stent-Graft
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137
5. The caliber of the iliac and the femoral arteries must
be sufficient to accept the delivery sheath.
6. Acute aortic dissections are excluded because the intimal flap is flimsy and easily injured by the edge of
the stent-graft. However, it usually thickens in the
chronic phase. Patients with chronic type B aortic
dissections are therefore suitable candidates even if
they have very small true lumen with compression of
the large false lumen.
7. Patients with connective tissue disorders (e.g., Marfan's syndrome) are excluded.
12.3 Outcome
12.3.1 Immediate Results and In-Hospital Course
Single-branched stent-graft placement was technically
successful in 86% (30/35 patients), double-branched in
67% (2/3 patients), and triple-branched in 70% (7/10)
of patients (Fig. 12.8). The procedure was terminated
before completion in nine patients, either because of a
complication (one patient) or because the stent-graft
did not pass through the delivery sheath used (eight patients). There were three deaths in the perioperative
period. The causes were rupture of the coiled external
iliac artery, acute pancreatitis due to microembolization, and massive bleeding from the left carotid artery
puncture site.
Other major complications included stroke in one
patient, reversible neurological event in one patient,
new aortic dissection in one patient, rupture of the external iliac artery in one patient, and severe graft stenosis in one patient. Of the major complications, the arterial rupture during the withdrawal of the delivery
sheath was successfully managed by stent-grafting of
the external iliac artery and the severe graft stenosis at
the main graft body was corrected by deployment of
metal stents.
12.3.2 Clinical Follow-Up
Follow-up for a period averaging 37 months (range, 4
months to 8.5 years) was available for 37 patients of the
39 patients in whom the procedure was completed; one
died of acute pancreatitis in the perioperative period
and one was lost to follow-up. There were three procedure-related deaths. The causes were infection in one
patient, rupture of the treated aneurysm in one patient,
and helium gas embolism during secondary stent-graft
intervention in one patient. Four late deaths occurred
from other causes (two due to pneumonia, one due to
colon cancer, one due to rupture of a concomitant abdominal aortic aneurysm). Four patients had persistent
endoleaks; three patients were successfully treated by
additional catheter-based interventions.
Late graft disruption, which was caused by the defect
of the graft fabric on the manufacturing process, occurred in eight patients. Of the eight patients, six received second stent-graft intervention; one died and five
were successfully treated by the placement of an overlapping stent-graft. Of the remaining two patients, one
died of aneurysm rupture and the other declined
further intervention. The other major complications included late graft thrombosis of the left subclavian artery in one patient with freedom from symptoms and
late endoleak in one patient. The leakage caused by a
gap between the stent-graft and the aorta at the proximal edge was eliminated by the placement of a straight
stent-graft.
With regard to changes in the maximum diameter of
the aneurysm sac as assessed by computed tomography,
18 of the 37 patients (49%) had a reduction (Fig. 12.9),
12 patients (32%) had no change, and seven patients
(19%) had an increase (one with a persistent leak, two
with late graft disruption, three with no demonstrable
endoleak, one with residual reentries in a type B aortic
dissection).
ab
Fig. 12.8. Triple-branched stent-graft for treatment of aortic
arch aneurysm.
strates a huge transverse aortic arch aneurysm.
tained after stent-graft placement shows complete exclusion of
the aneurysm
a Computed tomography (CT) image demon-
b CT image ob-
Fig. 12.9. Triple-branched stent-graft for treatment of aortic
arch aneurysm. A CT image demonstrates a transverse aortic
arch aneurysm. B CT image obtained 2 years after stent-graft
placement shows aneurysm shrinkage
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III. Treatment of Thoracic Degenerative Aortic Aneurysms
a
ef
Fig. 12.10. Aortograms in a 51-year-old woman with a type B
dissection: a, b aortogram shows the entry just beyond the left
subclavian artery; c, d aortogram after the procedure shows a
good flow of contrast medium through the single-branched
b c d
stent-graft with no leakage into the false lumen. e, f CT images
taken 8 years after single-branched stent-graft placement reveals a shrinkage of the false lumen, with absence of contrast
enhancement into the false lumen
12.4 Conclusion
Endovascular repair with a branched stent-graft has the
advantage of being remarkably less invasive compared
with conventional surgical treatment and is applicable
to complex aneurysms such as aortic arch aneurysms
[9, 11]. Considering most of the patients in our series
were at surgical high risk, the immediate and follow-up
results of endovascular repair with the Inoue branched
stent-graft appear to be favorable (Fig. 12.10). However,
further technical refinements and extensive clinical
trials will be needed before the procedure can become
the primary treatment for horizontal aneurysms.
Acknowledgements. The authors thank Yuki Yoshida for
the English translation of the manuscript.
References
1. Blum U et al. (1997) Endoluminal stent-grafts for infrarenal abdominal aortic aneurysms. N Eng J Med 336:13±20.
2. Crawford ES et al. (1979) Treatment of aneurysm of transverse aortic arch. J Thorac Cardiovasc Surg 78:383±393.
3. Crawford ES et al. (1989) Surgical treatment of aneurysm
and/or dissection of the ascending aorta, transverse aortic
arch, and ascending aorta and transverse aortic arch: factors influencing survival in 717 patients. J Thorac Cardiovasc Surg 98:659±674.
4. Dake MD et al. (1994) Transluminal placement of endovascular stent-graft for the treatment of descending thoracic aortic aneurysms. N Eng J Med 331:1729±1734.
K. Inoue et al. Chapter 12 Management of the Horizontal Aorta with the Inoue Branched Stent-Graft
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5. Dotter CT (1969) Transluminally-placed coilsoring endoarterial tube grafts: long-term patency in canine popliteal
artery. Invest Radiol 4:329±332.
6. Ergin MA et al. (1994) Hypothermic circulatory arrest in
operations on the thoracic aorta: determinants of operative mortality and neurologic outcome. J Thorac Cardiovasc Surg 107:788±799.
7. Inoue K et al. (1996) Clinical endovascular placement of
branched graft for type B aortic dissection. J Thorac Cardiovasc Surg 112:1111±1113.
8. Inoue K et al. (1997) Clinical application of transluminal
endovascular graft placement for aortic aneurysms. Ann
Thorac Surg 63:522±528.
9. Inoue K et al. (1997) Transluminal endovascular branched
graft placement for a pseudoaneurysm: reconstruction of
the descending thoracic aorta including the celiac axis. J
Vasc Cardiovasc Surg 114:859±861.
10. Inoue K et al. (1999) Aortic arch reconstruction by transluminally placed endovascular branched stent graft. Circulation 100(Suppl II):316±321.
11. Inoue K et al. (2001) Successful endovascular repair of
juxtarenal and suprarenal aortic aneurysms with a
branched stent graft. J Vasc Surg 33:1087±1092.
12. Miller DC et al. (1979) Operative treatment of aortic dissections: experience with 125 patients over a sixteen-year
period. J Thorac Cardiovasc Surg 78:365±382.
13. Mitchell RS et al. (1996) Endovascular stent-graft repair
of thoracic aortic aneurysm. J Thorac Cardiovasc Surg
111:1054±1062.
14. Moreno-Cabral CE et al. (1984) Degenerative and atherosclerotic aneurysms of the thoracic aorta: determinants of
early and late surgical outcome. J Thorac Cardiovasc Surg
88:1020±1032.
15. Okita Y et al. (1998) Mortality and cerebral outcome in
patients who underwent aortic arch operations using deep
hypothermic circulatory arrest with retrograde cerebral
perfusion: no relation of early death, stroke, and delirium
to the duration of circulatory arrest. J Thorac Cardiovasc
Surg 115:129±138.
16. Ohki T et al. (1999) Efficacy of a filter device in the prevention of embolic events during carotid angioplasty and
stenting: an ex vivo analysis. J Vasc Surg 30:1034±1044.
17. Parodi JC et al. (1991) Transfemoral intraluminal graft
implantation for abdominal aortic aneurysms. Ann Vasc
Surg 5:491±499.
18. Pressler V, McNamara JJ (1985) Aneurysm of the thoracic
aorta. Review of 260 cases. J Thorac Cardiovasc Surg
89:50±54.
19. Skupin M et al. (1990) Results of surgical repair for 110
thoracic aortic aneurysms. J Thorac Cardiovasc Surg
38:175±180.
20. Theron JG et al. (1996) Carotid artery stenosis: treatment
with protected balloon angioplasty and stent placement.
Radiology 201:627±636.
Distal Aortic Perfusion
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and Selective Visceral Perfusion
Charles C. Miller III, Anthony L. Estrera,
Tam T. T. Huynh, Eyal E. Porat, Hazim J. Safi
Chapter
13
Contents
13.1 Introduction ......................
13.2 Operative Technique and Adjuncts .......... 142
13.2.1 Cerebrospinal Fluid Drainage .......142
13.2.2 Thoracoabdominal Incision ......... 143
13.2.3 Diaphragm Preservation .......... 143
13.2.4 Distal Aortic Perfusion ........... 143
13.2.5 Sequential Cross-Clamping ......... 144
13.2.6 Reattachment of Intercostal Arteries . . . 144
13.2.7 Visceral and Renal Perfusion ........ 146
13.3 Impact of Adjuncts on Outcome ........... 147
13.3.1 Neurological Deficit: Immediate
and Delayed ..................
13.3.2 Renal Failure ................. 148
13.3.3 Aortic Dissection ...............149
13.4 Summary ........................ 149
141
147
13.1 Introduction
Thoracoabdominal aortic aneurysm repair was first performed by Etheredge [1] in 1955. Using a temporary
shunt to divert blood flow from the distal thoracic aorta
to the distal abdominal aorta, Etheredge excised a thoracoabdominal aortic aneurysm and restored blood flow
by inserting a homograft tube. De Bakey reported a
similar shunt and homograft technique in 1956. Later
that year, De Bakey [2] began to use a Dacron tube graft
that was sewn to the descending thoracic aorta and infrarenal abdominal aorta, and sequentially performed
separate bypass grafts of the celiac, superior mesenteric
and both renal arteries. This became the mainstay of
thoracoabdominal aortic aneurysm repair in its new beginning, because of its relative simplicity and reduced
ischemic insult to the viscera and kidneys. In 1965,
Crawford and the Baylor group then started to set the
standard in thoracoabdominal aortic surgery, as they
recruited large volumes of patients. Crawford's technique stemmed primarily from the early works of Matas
and Carrell, and encompassed three basic principles of
aortic surgery: the inclusion technique, use of a Dacron
tube graft conduit, and reimplantation of visceral and
renal arteries. In 1888, Matas [3] had first repaired an
aneurysm of the brachial artery within the walls of the
aneurysm, an inclusion technique later termed as endoaneurysmorrhaphy. On the other hand, direct reattachment of visceral arteries to a hole made in the prosthetic graft was pioneered by Carrell [4], who had experimented with different methods for reattaching
smaller vessels to larger ones, at the turn of the twentieth century. Creech [5] reported his approach for thoracoabdominal aortic aneurysm repair, in 1966. Thoracoabdominal aortic repair in this early time, however, was
still very arduous, an extremely lengthy procedure, and
associated with severe ischemia of the spinal cord, viscera and kidneys.
Connolly et al. [6] of Irvine, California, were the first
to use the pulsatile left heart bypass as an adjunct for
repair of the descending thoracic aneurysm. Korompai
[7], at Scott and White Clinic in Temple, used an ingenious method to perfuse the viscera, by diverting blood
from the descending thoracic aorta via a branched cannula connected to the celiac axis, superior mesenteric
and both renal arteries. In the mid-1970s, after trying
out various adjuncts, Crawford et al. [8] settled on the
clamp-and-go technique, because this simplified the
procedure, shortened the length of the operation and
produced good results. The modern era of repair of
thoracoabdominal aortic aneurysm was then ushered
in. However, high rates of postoperative paraplegia remained, and adjuncts continued to be explored widely
into the 1980s.
The original experimental work of Spencer, Cunningham, Laschinger and others at John Hopkins University
enlightened the surgical community to the significance
of intercostal artery reattachment in thoracoabdominal
aortic repair. Subsequently, Cunningham et al. [9, 10]
proposed the combined use of distal aortic perfusion
and somatosensory-evoked potential (SSEP) to identify
the artery of Adamkiewicz. In contrast, Crawford et al.
[11] reported high rates of false positives and false negatives in SSEP changes when correlated with postoperative neurological deficit. In 1988, Hollier [12], while at
the Mayo Clinic, established the use of perioperative ce-
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III. Treatment of Thoracic Degenerative Aortic Aneurysms
Fig. 13.1. Thoracoabdominal aortic aneurysm classification. Ex-
tent I, distal to the left subclavian artery to above the renal arteries. Extent II, distal to the left subclavian artery to below
the renal arteries. Extent III, from the sixth intercostal space to
below the renal arteries. Extent IV, from the 12th intercostal
space to the iliac bifurcation (total abdominal aorta). The original Crawford classification comprises extent I to extent IV. We
have since added extent V, from below the sixth intercostal
space to above the renal arteries
rebrospinal fluid (CSF) drainage, and reported a dramatic reduction in the incidence of paraplegia. In a
subsequent randomized clinical trial, Crawford et al.
[13] showed that CSF drainage provided no significant
benefit; however, intraoperative CSF drainage was allowed only up to 50 mL, and this limitation may have
been the reason for the negative result of their study.
Because adjuncts had been up to now largely unsatisfactory, protection of the spinal cord by simply reducing
the aortic cross-clamp time became the focus. To minimize the ischemic time to aortic segments, sequential
clamping of the aorta was essential to the clamp-and-go
technique. Also during this period, the classification of
the extent of thoracoabdominal aortic aneurysms (Fig.
13.1) was solidified, to permit meaningful comparisons
between various surgical groups and methods [14].
The 1990s were characterized by further experiments
with adjuncts, and different centers concentrated on different techniques, including hypothermia [15, 16] and
regional spinal cord cooling [17]. Crawford's cumulative
work was reviewed by Svensson et al. [18] in a landmark paper published in 1993. The incidence of neurological deficit was correlated with the extent of aneurysm, clamp time, rupture, age, proximal aortic aneurysm and renal dysfunction [18]. Simple clamp-and-go
technique was virtually abandoned [16, 17,19]. In 1992,
after several years of animal experiments and promising
clinical results reported by ourselves and other investigators, we adopted the combined adjunct distal aortic
perfusion and CSF drainage for all patients undergoing
thoracoabdominal aortic repair [19, 20]. We then observed considerable improvement in patient outcome.
In this chapter, we will discuss the adjuncts of distal
aortic perfusion, CSF drainage, moderate hypothermia
and visceral perfusion, and review their impact on neurological deficits and organ protection.
13.2 Operative Technique and Adjuncts
The patient is brought to the operating room and
placed in the supine position on the operating table and
prepared for surgery. The right radial artery is cannulated for continuous arterial pressure monitoring. General anesthesia is induced. Endotracheal intubation of
the patient is established using a double lumen tube for
selective right lung ventilation during surgery. A sheath
is inserted in the internal jugular vein, and a Swan±
Ganz catheter is floated into the pulmonary artery for
continuous monitoring of the central venous and pulmonary artery pressures. Large-bore central and peripheral venous lines are established for fluid and blood
replacement therapy. Temperature probes are placed in
the patient's nasopharynx and bladder (or rectum).
Electrodes are attached to the scalp for an electroencephalogram (EEG) and along the spinal cord for SSEP
to assess the central nervous system and spinal cord
function, respectively. Although a detailed account of
the essential anesthetic care during thoracoabdominal
aortic repair is beyond the scope of this chapter, the
importance of adequate maintenance of systemic arterial pressure with judicious blood transfusion cannot be
overemphasized, as perfusion of vital organs depends
on the systemic pressure.
13.2.1 Cerebrospinal Fluid Drainage
When the descending thoracic aorta is cross-clamped,
the spinal cord is rendered ischemic because of decreased perfusion to the spinal cord and consequent increased CSF pressure. The rationale for our use of CSF
drainage is to increase the spinal cord perfusion pressure directly with distal aortic perfusion, and indirectly
by reducing CSF pressure. Once all catheters, probes
Fig. 13.2. Placement of the lumbar catheter in the third or
fourth lumbar space to provide cerebrospinal fluid drainage
and pressure monitoring
C. C. Miller et al. Chapter 13 Distal Aortic Perfusion and Selective Visceral Perfusion
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143
and lines are in place, we reposition the patient on his
or her right side, flexing the knees to open the space
between the vertebrae. The anesthesiologist inserts a
catheter in the third or fourth lumbar space and advances it for about 5 cm (Fig. 13.2). CSF pressure is
kept below 10 mmHg throughout the surgery and for
3 days postoperatively. Systemic hypotension is avoided
during and after surgery to prevent additional hypoperfusion of the spinal cord.
13.2.2 Thoracoabdominal Incision
Once the lumbar catheter is in place, we readjust the
patient's position on the operating table. The right lateral decubitus position is maintained on a bean bag,
and the patient's shoulders are placed at a right angle
to the edge of the table, with the left hip flexed at 608
to allow access to both groins. The patient is sterilely
cleansed and draped in the usual sterile fashion. We tailor the incision to fit the extent of the aneurysm
(Fig. 13.3). A full thoracoabdominal incision begins between the spine and vertebral border of the left scapula,
curves along the sixth rib across the costal cartilage in
an oblique line to the umbilicus, and then continues below the umbilicus to just above the symphysis pubis.
Resection of the sixth rib facilitates exposure and is
routinely performed for all thoracoabdominal aortic repair, except extent IV. Usually, a full thoracoabdominal
exploration is necessary for extents II, III and IV. A
modified thoracoabdominal incision begins in the same
way as a full thoracoabdominal incision, but ends at the
costal cartilage or above the umbilicus. A self-retaining
retractor placed firmly on the edges of the incision
maintains full thoracic and abdominal exposure during
the procedure. The left lung is deflated. Mobilization of
the aorta begins at the level of the hilum of the lung,
cephalad to the proximal descending thoracic aorta. We
identify the ligamentum arteriosum and transect it, taking care to avoid injury to the adjacent left recurrent
laryngeal nerve. The extent of the distal abdominal an-
eurysm is assessed. For modified thoracoabdominal exploration, the diaphragm is retracted downward to expose the infradiaphragmatic aorta. When the aortic aneurysm extends below the renal arteries, we continue
the full thoracoabdominal exploration below the diaphragm.
13.2.3 Diaphragm Preservation
We have found that diaphragm preservation during
thoracoabdominal aortic repair results in earlier weaning from mechanical ventilation, and consequently a
shorter length of hospital stay [21, 22]. Since 1994,
rather than dividing the diaphragm, we cut only the
muscular portion, leaving the central tendinous portion
intact and preserving the phrenic nerve (Fig. 13.4). This
technique permits maintenance of pulmonary mechanics that more closely reflect normal function, and
hence we are able to wean patients earlier from mechanical ventilation. After cutting only the muscular
portion of the diaphragm, a retroperitoneal plane is developed, mobilizing the spleen, bowel loops and left
kidney to the right side of the abdominal aorta (medial
visceral rotation).
13.2.4 Distal Aortic Perfusion
Aortic cross-clamping not only causes distal end-organ
ischemia, but can also lead to proximal systemic hypertension and left ventricular distension. Left ventricular
distension can lead to increased wall stress and decreased subendocardial perfusion. To protect the spinal
Fig. 13.3. Thoracoabdominal incisions tailored for aneurysm ex-
tent (see text)
Fig. 13.4. Previously the diaphragm was completely divided (left);
currently only the muscular portion of the diaphragm is cut
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III. Treatment of Thoracic Degenerative Aortic Aneurysms
Fig. 13.5. Distal aortic perfusion from the left pulmonary vein
to the left femoral artery
Fig. 13.6. The pericardium is opened for cannulation of the left
lower pulmonary vein (left). If the pericardium is not properly
opened (middle), tamponade can occur with concealed leakage
from the pulmonary vein after decannulation (right)
graft or severe arteriosclerotic occlusive disease), the
abdominal aorta or distal thoracic aorta is used instead.
Distal aortic perfusion is initiated. We use passive moderate hypothermia (i.e., the patient's body temperature
is allowed to drift to 32±34 8C). Body temperature drop
below 32 8C is avoided to prevent the occurrence of ventricular arrhythmias. Our perfusion circuit includes a
heat exchanger to permit active warming.
cord, reduce proximal hypertension, minimize cardiac
ischemia and ªunloadº the heart, we routinely use distal
aortic perfusion. Afterload-reducing pharmacologic
agents such as nitrates are frequently used to further
protect the heart. But we no longer use nitroprusside as
an afterload-reducing agent, as we have observed precipitous systemic hypotension and a paradoxical increase
in CSF pressure associated with its use. Occasionally,
severe cardiac dysfunction may require mechanical support utilizing intraaortic balloon counterpulsation. To
prepare for distal aortic perfusion the patient receives a
dose of 1 mg/kg of heparin as an anticoagulant. The
pericardium is opened posterior to the left phrenic
nerve to allow direct visualization of the pulmonary
veins and left atrium. The lower pulmonary vein is cannulated and a cannula is inserted and connected to a
BioMedicus pump with an on-line heat exchanger
(Fig. 13.5). Two potential problems can arise if the pericardium is not opened properly: first, the cannula is
placed mistakenly in the pericardial space rather than
the pulmonary vein, and concealed leakage from the
pulmonary vein after the cannula is removed can cause
pericardial tamponade (Fig. 13.6). To complete the distal aortic perfusion circuit, the left common femoral artery is exposed, and arterial inflow from the pump is
generally established through the left common femoral
artery. When the left femoral artery is not accessible
(e.g., in the presence of an existing femoral prosthetic
13.2.5 Sequential Cross-Clamping
We use sequential aortic cross-clamping to minimize
organ ischemia, beginning either proximal or distal to
left subclavian artery and at the mid-descending thoracic aorta (Fig. 13.7a). The proximal aortic neck is transected completely and separated from the underlying
esophagus to prevent the formation of esophageal-graft
fistula (Fig. 13.7 b). To replace the aorta we use a woven
Dacron tube graft that is either infiltrated with gelatin
or impregnated with collagen. We suture the proximal
graft to the descending thoracic aorta using a 3-0 or a
2-0 monofilament polypropylene suture in a running
fashion. Distal aortic perfusion provides continuous
perfusion to the spinal cord, viscera and kidneys during
this period. After completion of the proximal anastomosis, the distal clamp is released and reapplied onto the
abdominal aorta above the celiac axis.
13.2.6 Reattachment of Intercostal Arteries
Next, we reattach the patent intercostal arteries. We
identify the lower intercostal arteries for reattachment
to the graft. Most commonly the anterior radicular artery (also known as the artery of Adamkiewicz), the
C. C. Miller et al. Chapter 13 Distal Aortic Perfusion and Selective Visceral Perfusion
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145
a
cd
b
ef
Fig. 13.7. a Application of the proximal and distal clamps in se-
quential clamping, and the proximal part of the aneurysm is
opened.
from the esophagus. c An elliptical hole is cut in the graft, and
the lower intercostal arteries are reattached as a patch to the
graft.
anastomosis, and the distal clamp is on the distal infrarenal
aorta. Catheters are inserted into the celiac, superior mesenteric, and renal arteries to permit perfusion. An elliptical hole is
b The aorta is completely transected and separated
d The proximal clamp is placed beyond the intercostal
made in the graft for reimplantation of the visceral and renal
arteries.
Cold lactated Ringer's solution (4 8C) is used to cool the kidneys to approximately 15 8C, and the viscera is perfused with
cold blood (48C). The lower extremities continue to be
warmed.
planted to the aortic graft, the proximal clamp is applied beyond this anastomosis, and the distal anastomosis is fashioned
from a graft to the infrarenal aorta
e Integrated visceral perfusion and cooling circuit.
f Once the visceral and renal arteries have been reim-
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III. Treatment of Thoracic Degenerative Aortic Aneurysms
major arterial blood supply to the spinal cord, takes its
origin from one of the lower intercostal arteries (T9±
T12) with or without additional collateral branches
from nearby intercostal arteries. Reimplantation of intercostal arteries to the aortic graft therefore plays a
critical role in spinal cord protection. Paradoxically before we began to use adjuncts, reattachment of intercostal arteries was shown to be a risk factor for postoperative neurological deficit, owing to the longer period of
unprotected cross-clamp time required to perform this
task. However, several years after implementing CSF
drainage and distal aortic perfusion we studied the relationship of neurological deficits to ligation, reimplantation and preexisting occlusion of intercostal arteries in
patients undergoing thoracoabdominal aortic repair. We
found that ligation of patent lower intercostal arteries
(T9±T12) increased the risk of paraplegia [23]. Therefore, we reattach all patent lower intercostal arteries
from T9 to T12, either together as a patch to an elliptical side hole made in the Dacron graft or, if the intercostal arteries are too far apart, separately as buttons or
using interposition bypass grafts (Fig. 13.7 c). Backbleeding from patent intercostal arteries can be minimized with temporary placement and inflation of balloon catheters (size 3F) prior to reimplantation. In general, we ligate the upper (above T8) intercostal arteries.
If the lower intercostal arteries are occluded we reimplant the patent upper intercostal arteries, because these
arteries may have assumed a critical collateral system to
the anterior spinal artery. After completion of the intercostal reattachment, the proximal clamp is released
from the aorta and reapplied onto the aortic graft below
the intercostal patch, restoring pulsatile flow to the reattached intercostal arteries.
nal arteries are reattached as an island. Alternatively,
separate bypass grafts to the individual artery may be
necessary if they are not in close proximity. Once the
visceral anastomosis is completed, the clamp is moved
down on the graft to restore the pulsatile flow to the
viscera and renal arteries (Fig. 13.7 f). At this moment,
the patient is given an injection of indigo carmine. The
dye urinary clearance time is used as an indicator of
a
13.2.7 Visceral and Renal Perfusion
The distal clamp is moved onto the distal abdominal
aorta below the renal arteries, the upper abdominal aortic aneurysm is opened and the walls are retracted,
using 2-0 retraction sutures. The celiac, superior mesenteric and both renal arteries are identified and perfused through individual no. 9 or no. 12 Pruitt (Cryolife,
St. Petersburg, FL, USA) catheters (Fig. 13.7 d). Currently, we perfuse the celiac and superior mesenteric arteries with cold blood. For the kidneys, an initial bolus
of 300±800 mL of cold lactated Ringer's solution is infused into the left and right renal arteries, followed by
additional periodic 100-mL aliquots as needed, to maintain renal temperature around 15 8C (Fig. 13.7e). Renal
temperature is monitored directly by inserting a temperature probe in the left renal cortex. The flow rate is
approximately 200 and 150 mL/min for the renal and
visceral arteries, respectively.
The aortic graft is passed through the aortic hiatus.
A side hole is made in the graft and the visceral and re-
b
Fig. 13.8. a Example of a Marfan patient with descending tho-
racic aortic aneurysm (artist's illustration, left); this was re-
paired but he subsequently developed recurrent extent II thoracoabdominal aortic aneurysm (artist's illustration and preoperative computed tomography, right).
tent II thoracoabdominal aortic aneurysm (postoperative computed tomography and artist's illustration)
b Completed repair of ex-
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