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262 Elefteriades and Griepp
to a separate vertically oriented graft, which is then secured to the main graft
traversing from the ascending aorta to the descending aorta (22). Griepp even
constructs the nonanatomic graft first in some cases, to permit brain perfusion
via a side-arm from the arterial line. These techniques represent another valua-
ble tool for the surgeon’s armamentarium in acute dissections involving the
aortic arch.
By applying one of these multiple techniques, the experienced aortic
surgeon can accomplish formal arch replacement for the minority of patients who
are not adequately served by the hemiarch technique. This minority of patients is
usually distinguished by origin of the dissection at an inciting intimal tear in the
aortic arch itself. It goes without saying that the surgeon would not even be aware
of this situation without the unique opportunity for visualization afforded by the
open distal technique.
Chronic Arch Dissection
One more vitally important technical point deserves to be emphasized. It is
generally agreed that in acute type A aortic dissection, the two dissected layers
should be approximated to obliterate the false lumen. In contrast, for chronic
aortic dissection, the two layers should not be approximated, because to do so
would risk depriving the vital organs of circulation that has been flowing through
the false lumen (Fig. 9). The author has witnessed from other centers the devas-
tating cerebral results consequent upon ignoring this important caveat for chronic
arch dissections.
ACUTE DESCENDING AORTIC DISSECTION
We recently reviewed the outcome of 100 consecutive patients with acute descending
(type B) aortic dissection treated at our institution (23). This experience provides
a useful “snapshot” of the “nature of the beast” of acute descending aortic
dis section (Fig. 10). The upshot is that, in most cases, descending aortic dissection
is much less morbid than its ascending counterpart. In fact, as can be seen in
Figure 10, 91% of patients were discharged from hospital alive after treatment for
acute descending aortic dissection.
At our institution, we follow what we call the “complication-specific
approach” to acute descending aortic dissection. The cornerstone of this approach
is that, absent specific complications, no surgical treatment is required. We simply
apply “anti-impulse” therapy, as described earlier in this textbook. Most patients
are relieved of their pain and continue to an uneventful recovery and hospital
discharge in a week to ten days, after at least one follow-up aortic imaging study
demonstrates stability of the dissection.
The development of various complications of acute descending aortic
dissection mandates that operation be performed. We predicate the specific
operation on the specific complication at hand: Rupture requires traditional
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Surgical Procedures: A Primer 263
replacement of the descending aorta, as described in the chapter on “Rupture”
earlier in this textbook. (We often identify a state of “impending rupture,” preferring
to operate before the patient bleeds internally. This is usually a matter of clinical
judgment and experience—with warning signs such as persistent pain, bloody
pleural effusion, or small amounts of extravasated contrast on CT scan. Treatment
is as for realized rupture.) Uncontrolled pain and rapid expansion of the aorta
(on repeat imaging studies) also require operation, which once again should be
formal aortic replacement. Organ ischemia is the most common complication, and
this also requires operation—urgent operation, in fact, so as to save organs and/or
limbs. Here, we prefer an operation different from aortic replacement—namely,
the “fenestration” procedure (Fig. 11). Although developed many decades ago,
this operation is predicated on the still valid concept that taking the pressure
off the false lumen (by creating a wide communication—or “fenestra,” Latin for
“window”—to drain the false lumen into the true lumen) can restore blood flow
to the affected organ (Fig. 12). We have found this procedure, performed quickly
and effectively through a retroperitoneal approach, to be extremely effective in
Figure 9 Schematic showing danger of obliterating false lumen in chronic aortic
dissection—to do so may obliterate flow to vital organs dependent on the false lumen,
including the brain.
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264 Elefteriades and Griepp
Figure 11 The fenestration operation. A retroperitoneal approach is made (A). The infra-
renal aorta is exposed (B). The aorta is transected (C). A large flap is removed from the
upper portion (fenestration) (D). The distal aorta is reconstituted by reapproximating the
dissected layers by simple suture. The two ends of the transected aorta—the upper fenes-
trated end and the lower reconstituted end—are reattached by running suture (E). No graft
material is required. No perfusion adjuncts are required.
Figure 10 Outcome of 100 acute descending aortic dissections. Note relative benignity
of outcome compared to ascending dissection. Source: From Ref. 23.
Natural Behavior of 100 Consecutive,
Type B Aortic Dissections
6 Aortic
9 Died
8 Rupture
6 Retrograde dissection
31 Complicated 60 Uncomplicated
91 Survived
3 Non-aortic
4 Uncontrolled pain
12 Expansion
100 Patients
Vascular complications:
5 renal, 5 spinal cord
5 lower extremity
2 abdominal
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Surgical Procedures: A Primer 265
restoring blood flow to affected organs (24,25). This procedure is extremely well
tolerated by these very critically ill patients.
Fenestration is especially attractive an option, as early operation on the
acutely dissected aorta has traditionally been fraught with high mortality and
morbidity. One must remember that the descending aorta has only half the lamel-
lar units of the ascending. In acute dissection, the outer, adventitial, layer has only
a small number of lamellae to hold the surgeon’s sutures. We found, in examining
microscopically many dozens of resected aortic dissection specimens, that within
about two weeks, significant fibrosis develops in the dissection plane; we believe
this fibrotic process is the reason that surgery after three to four weeks following
acute descending aortic dissection is much, much safer—if surgery can possibly
be delayed [A very recent publication by the Mt. Sinai group is the first to show
improved, in fact excellent, results with early direct operation on the descending
aorta (26)]. In many cases, the fenestration may be performed percutaneously by
catheter in the present era. We have no objection to such an approach. In fact,
there may be a larger role for interventional management of acute descending
aortic dissection. The INSTEAD trial is looking at the impact of routine stenting
of subacute descending aortic dissections, with the thesis that obliterating the
false lumen at the time of occurrence of dissection may have beneficial effects
later on—perhaps decreasing the rate of growth of the dissected descending aorta
or the onset of late complications (27). Such interventional treatments are covered
fully elsewhere in this textbook.
As with chronic ascending aortic dissections, one must never obliterate the
false lumen in chronic descending aortic dissections, as organs will be chronically
dependent on flow through the false lumen.
Figure 12 Schematic diagram of mode of benefit from fenestration.
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266 Elefteriades and Griepp
CONCLUSION
Acute descending aortic dissection is less lethal than its aortic counterpart, and
“anti-impulse” therapy is effective in preserving life. When surgery is necessary,
a “complication-specific” approach yields satisfactory results.
Although acute type A aortic dissection remains a serious condition, the
safety of operation for this pathologic entity has certainly improved. At experienced
aortic centers, mortality for acute type A aortic dissection has dropped to the
lowest double digits, approaching the single figures (5). Improvements in surgical
experience and technique have certainly been important factors in achieving these
excellent results. Other factors include the widespread availability of impregnated
grafts, use of activated clotting time nomograms for calculation of protamine doses,
advent of effective antifibrinolytic drugs (Amicar and Trasylol), and commercial
availability of biologic glues (Bioglue).
Acute aortic dissection remains an extremely serious foe, with wiles that
will test even the most experienced operator, especially when the aortic arch is
involved. This condition continues to prove the veracity of Osler’s pronouncement
some 100 years ago (courtesy of Dr. Vincent Gott), “There is no condition more
conducive to clinical humility than aneurysm of the aorta.”
REFERENCES
1. Shiono M, Hata M, Sezai A, Iida M, Yagi S, Negishi N. Emergency surgery for acute
type a aortic dissection in octogenarians. Ann Thorac Surg 2006; 82:554–559.
2. Scholl FG, Coady MA, Davies R, et al. Interval or permanent non-operative manage-
ment of type a aortic dissections. Arch Surg 1999; 134(4):402–406.
3. Tittle SL, Lynch RJ, Cole PE, et al. Midterm follow-up of penetrating ulcer and intra-
mural hematoma of the aorta. J Thorac Cardiovasc Surg 2002; 123:1051–1059.
4. Motoyoshi N, Moizumi Y, Komatsu T, Tabayashi K. Intramural hematoma and dissec-
tion involving ascending aorta: the clinical features and prognosis. Eur J Cardiothorac
Surg 2003; 24(2):237–242, discussion 242.
5. Elefteriades JA. What operation for acute type A dissection. J Thoracic Cardiovasc
Surg 2002; 123:201–203.
6. Kirsch M, Soustelle C, Houël R, Hillion ML, Loisance D. Risk factor analysis for
proximal and distal reoperations after surgery for acute type A aortic dissection.
J Thorac Cardiovasc Surg 2002; 123:318–325.
7. Casselman FP, Tan ES, Vermeulen FE, Kelder JC, Morshuis WJ, Schepens MA.
Durability of aortic valve preservation and root reconstruction in acute type A aortic
dissections. Ann Thorac Surg 2000; 70:1227–1233.
8. David TE, Armstrong S, Ivanov J, Barnard S. Surgery for acute type A aortic
dissection. Ann Thorac Surg 1999; 67:1999–2009.
9. Ehrlich MP, Ergin A, McCullough JN, et al. Results of immediate surgical treatment of
all acute type A aortic dissections. Circulation 2000; 102(19 suppl 3):III-248–252.
10. Elefteriades JA, ed. Diseases of the thoracic aorta. Cardiol Clin 1999:4.
11. Graeter TP, Langer F, Nikoloudakis N, Aicher D, Schafers HJ. Valve-preserving
operation in acute aortic dissection type A. Ann Thorac Surg 2000; 70:1460–1465.
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Surgical Procedures: A Primer 267
12. Kazui T, Washiyama N, Muhammad BA, et al. Extended total arch replacement for
acute type A aortic dissection: experience with seventy patients. J Thorac Cardiovasc
Surg 2000; 119:558–565.
13. Keane MG, Wiegers SE, Yang E, Ferrari VA, St. John Sutton MG, Bavaria JE.
Structural determinants of aortic regurgitation in type A dissection and the role of
valvular resuspension as determined by intraoperative transesophageal echocardio-
graphy. Am J Cardiol 2000; 85:604–610.
14. Luciani GB, Mazzucco A. Aortic insufficiency after surgical repair of acute type A
aortic dissection: incidence, indications for reoperation and medical management.
J Heart Valve Dis 2001; 10:12–18.
15. Niederhauser U, Rudinger H, Kunxli A, et al. Surgery for acute type a aortic dissection:
comparison of techniques. Eur J Cardiothorac Surg 2000; 18:307–312.
16. Nguyen B, Muller M, Kipfer B, et al. Different techniques of distal aortic repair in
acute type A dissection: impact on late aortic morphology and reoperation. Eur J
Cardiothorac Surg 1999; 15:496–501.
17. Pessotto R, Santini F, Pugliese P, et al. Preservation of the aortic valve in acute type A
dissection complicated by aortic regurgitation. Ann Thorac Surg 1999; 67:2010–2019.
18. Sabik JF, Lytle BW, Blackstone EH, McCarthy PM, Loop FD, Cosgrove DM. Long-
term effectiveness of operations for ascending aortic dissections. J Thorac Cardiovasc
Surg 2000; 119:946–962.
19. Sinatra R, Melina G, Pulitani I, Fiorani B, Ruvolo G, Marino B. Emergency operation
for acute type A aortic dissection: neurologic complications and early mortality. Ann
Thorac Surg 2001; 71:33–38.
20. David TE, Ivanov J, Armstrong S, Feindel CM, Webb GD. Aortic valve-sparing oper-
ations in patients with aneurysms of the aortic root or ascending aorta. Ann Thorac
Surg 2002; 74:S1758–S1761.
21. Yacoub MH, Gehle P, Chandrasekaran V, Birks EJ, Child A, Radley-Smith R. Late
results of a valve-sparing operation in patients with aneurysms of the ascending aorta
and root. J Thorac Cardiovasc Surg 2001; 126(6):1220–1221.
22. Galla JD, McCullough JN, Ergin MA, Apaydin AZ, Griepp RB. Surgical techniques.
Aortic arch and deep hypothermic circulatory arrest: real-life suspended animation.
Cardiol Clin 1999; 17(4):767–778. ix. Review.
23. Elefteriades JA, Lovoulos CJ, Coady MA, Tellides G, Kopf GS, Rizzo JA. Manage-
ment of descending aortic dissection. Ann Thorac Surg 1999; 67(6):2002–2005.
24. Elefteriades JA, Hammond GL, Gusberg RJ, Kopf GS, Baldwin JC. Fenestration
revisited. Arch Surg 1990; 125:786–790.
25. Morales DLS, Quin JA, Braxton JH, et al. Experimental confirmation of effectiveness
of fenestration in acute aortic dissection. Ann Thorac Surg 1998; 66:1679–1683.
26. Lansman SL, Hagle C, Fink D, et al. Acute type B aortic dissection: surgical therapy.
Ann Thorac Surg 2002; 74:S1833–S1835.
27. Nienaber CA, Zanetti S, KischeS, et al. Investigation of Stent grafts in patients with
type B aortic dissection: design of the INSTEAD trial—a prospective, multicenter,
European randomized trial. Am Heart J 2005; 149(4):592–599.
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268 Elefteriades and Griepp
DISCUSSION AND COMMENTARY
Questions for the Authors
When selecting an aortic prosthesis in the setting of acute type A dissection, do the
usual tenets apply, or is a particular valve more suitable for the acute dissection
patient? Similarly, is it valuable, or unnecessary, to avoid the need for anticoagu-
lation in these patients?
Patient survival from the operation and the acute illness is Job #1. So, long-term
considerations are secondary.
It is helpful to avoid anticoagulation in patients with acute dissection,
although anticoagulation is not entirely contra-indicated. A biological valve cer-
tainly has advantages in this regard. However, a biological valve, by virtue of its
higher profile, may be more cumbersome to seat in the proximal aorta that has
been or will be reconstructed with a Teflon “sandwich.” A low-profile mechanical
valve has an advantage in this regard. The bottom line, then, is for the surgeon to
choose the valve that will make his operation the most expedient and secure.
If a composite graft is required, the choice will usually be for a pre- fabricated
mechanical valved conduit. In the acute setting, there will usually not be time to
make a biological valved conduit on the field. No pre-fabricated biological valved
conduits are currently available commercially in the United States.
Is it safe to use biological glue in the distal aortic sandwich, near the head
vessels?
This question is very well taken. We use extreme care in application of glue inside
the aorta. However, in the case of the sandwich, the glue is separated from the
lumen by the inner layer of the dissection. Also, a huge clinical experience, both
in Europe and in the United States, supports the safety of construction of a Teflon
“sandwich” with a biological glue for layer reapproximation and aortic wall
reconstitution.
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269
16
Endovascular Thoracic Aortic Stent
Grafting in Acute Aortic Catastrophes
Derek R. Brinster
Division of Cardiothoracic Surgery, Virginia Commonwealth University
Medical Center/Medical College of Virginia, Richmond, Virginia, U.S.A.
Wilson Y. Szeto and Joseph E. Bavaria
Division of Cardiac Surgery, University of Pennsylvania
Medical Center, Philadelphia, Pennsylvania, U.S.A.
INTRODUCTION
Thoracic aortic endovascular repair (TEVAR) has been shown to be an effective
treatment for many thoracic aortic conditions over the past few years. Although
there is no long-term data about the effectiveness of this radical and revolutionary
new therapy, the intermediate results have been promising. Interestingly, while the
initial applications of TEVAR have been in the elective treatment of thoracic aortic
conditions, TEVAR may have its most profound benefit in the catastrophic presen-
tations associated with acute aortic conditions. It is in the acute aortic condition
that standard operative treatment has the highest mortality and morbidity rates.
It may be difficult to prove that TEVAR is actually superior to elective open
surgery for aneurismal disease because elective open surgery in the modern era is
quite successful. The same dilemma is true when comparing endovascular repair of
the abdominal aorta (EVAR) to standard open abdominal aortic aneurysm (AAA)
repair, as vascular surgeons have perfected open AAA repair with overall mortality
rates between 2% and 4% in most large published series.
TEVAR utilized in acute aortic presentations most probably will not suffer
from this ambiguity, as most acute thoracic aortic conditions, such as ruptured
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270 Brinster et al.
thoracic aneurysm, ruptured thoracic aortic dissection, branch artery malperfusion
in the setting of acute aortic dissection, and acute traumatic transection, have such
high medical and surgical morbidity and mortality rates that a minimally invasive
and anatomically successful treatment will be obviously beneficial.
ANATOMICAL REQUIREMENTS FOR STENTS/ TECHNICAL ASPECTS
Anatomical requirements and key technical considerations for successful TEVAR
revolve around answering the question: What makes a patient a suitable anatomi-
cal candidate for a thoracic aortic stent graft? The most important considerations
are listed in Table 1.
The initial assessment of a stent graft candidate begins with the preopera-
tive workup and evaluation. Key points of the history and physical exam should
include a detailed neurological and cardiovascular exam. Distal vascular pulses
and preoperative neurological deficiencies must be documented. Any previous
abdominal, pelvic, and inguinal surgeries should be noted. Previous surgery may
demand an alternate access route.
Extensive preoperative planning with appropriate imaging is mandatory.
The “gold standard” for preoperative evaluation is a computed tomography (CT)
angiogram, which includes the thorax, abdomen, pelvis, and femoral arteries.
Fine cut helical CT scanning with minimum of 3 mm slices is ideal. Medical
metrix systems (MMS, Lebanon, NH) reconstruction into a 3-D image allows
accurate assessment of the thoracic aorta and iliofemoral access. In those patients
who cannot receive a CT with contrast, magnetic resonance angiography is an
acceptable substitution.
Access
Safe access for thoracic aortic device deployment is the key to thoracic aortic stent
grafting. The majority of morbidity and mortality is a direct result of arterial access
complications (1). All thoracic endovascular devices are long (so as to reach the
Table 1 Important Anatomical Considerations When
Considering Thoracic Endovascular Aortic Repair
Iliofemoral and peripheral access
Suitability of the proximal and distal landing zones
Diameter
Intramural thrombus considerations
Tapering
Calcification
Aortic wall integrity e.g., Marfan’s, IMH, acute dissection
Distal aortic arch angulation (radius of curvature)
Thoracic aortic tortuosity
Branch vessel considerations
Left subclavian artery bypass
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Endovascular Thoracic Aortic Stent Grafting 271
descending aorta), of large caliber (to contain the thoracic aortic endoluminal
graft), and relatively stiff (to allow “pushability” through the ileo-femoral access
points and through the abdominal aorta). The management of delivery of the
thoracic aortic stent graft is often the most challenging aspect of the case.
Delivery systems of the current FDA approved Gore TAG (W. L. Gore Flagstaff,
A2) graft require sheaths ranging in size from 22 Fr to 24 Fr outer diameter. Other
devices, which have not been FDA approved, have similar size requirements for arte-
rial access, either with or without sheaths. Therefore, arterial access size must be
7.5–8.0 mm ID to be considered as a conduit.
Not only the size of the arterial vessels but the anatomy of the ileo-femoral
and abdominal aorta must be considered when planning the access route. Excessive
tortuosity and atherosclerosis with occlusive disease may provide barriers to safe
delivery of the endograft. In approximately 20% of patients, retroperitoneal access
to the common iliac arteries will be required due to issues of femoral or external
iliac artery size and/or tortuosity (2,3).
Careful review of preoperative studies will indicate which patients will have
difficult access. Patients with atherosclerotic occlusive iliac disease may be treated
with standard endovascular balloon angioplasty techniques to reduce the obstruc-
tion. Iliac stents should be avoided due to the potential interference of these stents
with the thoracic aortic access devices. These procedures on the access vessels
should be carried out at least six weeks before thoracic aortic stent grafting to
allow healing of the iliac postangioplasty and manipulation. At the completion
of thoracic aortic endografting, iliac stents may be placed if appropriate.
Access to the retroperitoneum allows several options for safe device deploy-
ment. The common iliac artery may be used for device deployment. An open
surgical conduit can be constructed via an end-to-end anastomosis or a side-to-side
anastomosis. A 10 mm Dacron conduit is commonly used and allows ample size
for insertion of all necessary devices. The conduit may be brought through a sepa-
rate counter-incision in the groin to allow better angulation of the relatively long
and stiff deployment devices. At the conclusion of the procedure, these conduits
may be used to revascularize distal obstructions if needed (Fig. 1A) (4).
Alternatively, the retroperitoneal iliac vessels or even the distal aorta may be
accessed using direct sheath insertion. A double pursestring of 4 – 0 Tycron is used
to secure the vessel and provide hemostasis with the application of two sets of
tourniquets. Direct needle puncture of the artery is followed by dilation and inser-
tion of the device. At completion, the device is removed and the pursestring sutures
are tied down (Fig. 1B) (4). Excessive tortuosity of the ilio-femoral arteries requires
adaptive strategies. The use of external manual manipulation provides a simple
method of straightening some of the tortuosity of the aorta and iliac arteries. During
fluoroscopy the operator’s hand can provide gentle force to the tortuous arterial
segment to allow straightening and subsequent endovascular access.
In cases of iliac artery tortuosity, advanced endovascular techniques may aid
in straightening these segments. The use of stiff wires or buddy wire techniques
can provide some degree of straightening of the diseased arteries. In severe cases
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