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with sensitivity and specificity both above 95%31 except where
obscured by the trachea. The limitation of TEE for routine diagnostic purposes is that it requires sedation and is relatively invasive
compared to other techniques to evaluate TAA, such as CT and magnetic resonance imaging (MRI) examinations (see later discussion).
Computed Tomography
Rapid advances in technology have put CTA in the forefront of
aortic imaging (see Chapter 14). Contemporary multidetector-row
CTA can acquire 320 simultaneous helices, creating high-resolution
images and providing better sensitivity and specificity than could
be obtained previously
detector scanners, CT was able to determine aortic aneurysm size
to within 0.2 mm.
Computed tomographic angiography is now a preferred imaging
modality for preoperative definition of aortic aneurysms because
of its accuracy. Computed tomography can define the proximal
and distal extension of AAAs
of the aneurysm to branch arteries.
undergoing AAA repair, both spiral CT and conventional contrast angiography were performed. Spiral CT had 100% sensitivity
for determining aneurysm extent and better sized the aneurysm
than angiography, but it revealed only 2 of 9 accessory renal arter-
36
ies.
In one study comparing CTA to conventional angiography,
CTA had 93% sensitivity and 96% specificity in determining clinically significant branch vessel stenoses (≥
of aneurysm.37 Computed tomographic angiography has replaced
angiography as the primary presurgical examination because it is
noninvasive and provides detailed information about the vessel
walls, such as inflammation, mural thrombus, and vascular calcification. Moreover, CTA creates better anatomical definition with
various 3D visualization techniques38 (Fig. 38-6). Also, it can diag-
nose abnormalities in adjacent structures. Recent data suggest that
multidetector CTA has similar image quality and diagnostic accuracy as MRA, with 91% sensitivity and 98% specificity.
Computed tomographic angiography also can demonstrate
mural calcification and, with 3D reconstruction, show aortic angu-
40
lation.
Placement of aortic stent grafts for AAA requires acquisition of specific anatomical information prior to the procedure.
The most important parameter measured prior to placement of
an endograft is the diameter of the neck. Modalities that create a
cross-sectional image, including CT, can accurately determine vessel diameter.
41,42
raphy (DSA) were compared in a prospective study of 61 patients
planned for aortic stent graft placement.
angiography and helical CT were similar in their ability to determine proximal aneurysm extent and aortic diameter, but CT performed better in imaging accessory renal arteries and detecting
32
(Figs. 38-4 and 38-5). Yet even with single-
33
34
and determine the relationship
35
In a study of 30 patients
85%) and the presence
39
Helical CT, MRA, and digital subtraction angiog-
43
Magnetic resonance
FIGURE 385 Three-dimensional (3D) reconstruction of abdominal
aortic aneurysm (AAA) from a multidetector computer tomography
angiographic (CTA) scan. Note infrarenal location of aneurysm, vascular
calcification in white, and tortuosity of iliac arteries.
renal artery stenosis. Currently, 3D CTA reconstruction is becoming
routine and may provide even better results than 2D images.
44
Postoperatively, CT imaging is directed at the primary complications of stent grafts: endoleaks, device failure, aneurysm expansion, and aneurysm rupture. Determining the type of endoleak has
important prognostic implications. In a study of 40 aortic stent graft
patients, CTA was superior to DSA in determining the presence of
endoleak, with a sensitivity of 92% for CTA and only 63% for DSA.
Computed tomographic angiography also is effective in detecting
stent graft migration, distortion, and destruction. Thus, CT imaging
is indicated for preprocedural planning and post-endograft surveillance. After the implantation, imaging typically is performed at 3, 6,
and 12 months and yearly thereafter.
42
Computed tomographic angiography also is useful to image
the thoracic aorta for diagnosis, follow-up, and perioperative
management of TAA (Fig. 38-7). Computed tomographic can be
used to follow aneurysm growth,
45
detecting changes as small
as a millimeter. Use of contrast permits evaluation of aneurysms
from any angle and the creation of 3D images. In one study of
49 patients, CT accurately assessed spinal cord circulation and
predicted the requirement for hypothermic circulatory arrest 94%
of the time.
46
Computed tomographic may also play an important
role in follow-up of thoracic endovascular grafts by demonstrating
volumetric changes in the aneurysm and thrombus suggestive of
a successful repair.
47
Computed tomographic angiography accurately assess the thoracic aorta prior to operation, assists in operative planning, and is the standard imaging modality for follow-up.
475
CH
38
CliniCAl EvAluATion of AoRTiC AnEuRysms
FIGURE 384 Coronal section of an x-ray multidetector computed
tomographic (CT) scan of abdomen. Large white arrow indicates the
abdominal aortic aneurysm.
Magnetic Resonance Imaging
Magnetic resonance imaging and angiography are also used to
image and characterize aortic aneurysms (see Chapter 13). The
technique has been used for diagnosis of AAA for more than
20 years
(
rysm diameter, longitudinal extent, involvement of branch vessels,
48
and is quite acceptable for preoperative evaluation
Fig. 38-8). Magnetic resonance angiography can determine aneu-
476
AB
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CH
38
FIGURE 386 A 62-year-old man
with abdominal aortic aneurysm
(AAA) before (A) and after (B)
placement of aortic stent. A,
Patient underwent contrast-enhanced
computed tomography (CT) for preinterventional evaluation of abdo minal
aorta and aneurysm, and for planning.
B, After successful placement of
stent, CT scan demonstrates effective
exclusion of aneurysm and restitution
of aortic lumen.
FIGURE 388 Maximal intensity projection (MIP) of magnetic
FIGURE 387 Sagittal view of computed tomographic (CT) image of
thorax, demonstrating aneurysm involving ascending aorta and aortic
arch, measuring more than 10 cm in diameter. (From Tomey MI, Murthy VL,
Beckman JA: Giant syphilitic aortic aneurysm: A case report and review of the literature.
Vasc Med 16:360–364, 2011.)
resonance angiogram (MRA) demonstrating a 4.7-cm suprarenal
abdominal aortic aneurysm (AAA).
ography is at least as good as CTA for postprocedural surveillance
of stent grafts. In a study of 108 patients, MRA diagnosed endole-
aks with sensitivity and specificity of 96% and 100%, respectively,
and proximity to renal arteries. Both MRI and gadolinium-enhanced
MRA have better than 90% sensitivity and specificity for determination of TAA.
specificity for detecting concordant stenoses in splanchnic, renal,
or iliac branches.
49
Moreover, MRA has better than 90% sensitivity and
50
Magnetic resonance angiography is an accurate method for
defining aortic anatomy, required prior to aortic endograft, and is
superior to duplex ultrasonography.
41,51
Magnetic resonance angi-
compared with 83% and 100% for CTA.30 Cine-MRA can show the
pulsatility of the aneurysm and quantify AAA wall motion before
and after endovascular graft placement to help identify endoleaks.
One of the more important issues associated with repair of the
thoracic aorta is identifying the artery of Adamkiewicz. This artery
arises most commonly from the left side of the aorta between T8
and L4 and supplies perfusion to the lower two thirds of the spinal
cord. Both CT and MR, with their high spatial resolution, visualize
FIGURE 389 Contrast abdominal aortography revealing infrarenal
abdominal aortic aneurysm (AAA). Note that angiogram cannot determine
aneurysm size, but can show that renal arteries are not involved.
the artery well.
CTA visualized the artery of Adamkiewicz via a clear identification
of the vascular anatomy.
52,53
In a series of 30 patients with TAA, both MRA and
54
Contrast Angiography
Contrast angiography is useful to define branch vessel anatomy and the longitudinal extent of aortic aneurysms (
Angiography, which provides information about the aortic lumen,
cannot accurately size an aneurysm because it does not visualize
the vessel wall or aneurysm thrombus. Digital subtraction angiography has similar accuracy to MRA and CTA in defining aneurysm
length and aortic anatomy prior to endograft placement. In a study
of 20 patients prior to endograft placement, length and diameter
measurements were similar between MRA and CT, but superior
51
to DSA.
Contrast angiography is less commonly performed than
noninvasive imaging studies because of its invasive nature, the
nephrotoxicity of contrast, and the lack of diagnostic superiority.
Once an aortic aneurysm is diagnosed, serial imaging studies
should be performed every 3 to 12 months until the rate of expansion
is 1 cm or more per year, or the diameter increases to a point that
merits surgical or endovascular repair (see Chapters 39 and 40).
REFERENCES
1. Tomey MI, Murthy VL, Beckman JA: Giant syphilitic aortic aneurysm: a case report and
review of the literature, Vasc Med 16:360–364, 2011.
2. Boulia SP, Metaxas E, Augoulea M, et al: Superior vena cava syndrome due to giant aortic
aneurysm, Asian Cardiovasc Thorac Ann 18:396–397, 2010.
3. Karkos CD, Mukhopadhyay U, Papakostas I, et al: Abdominal aortic aneurysm: the role of
clinical examination and opportunistic detection, Eur J Vasc Endovasc Surg 19:299–303,
2000.
4. Lederle FA, Simel DL: The rational clinical examination. Does this patient have abdominal
aortic aneurysm? JAMA 281:77–82, 1999.
5. Lederle FA, Walker JM, Reinke DB: Selective screening for abdominal aortic aneurysms with
physical examination and ultrasound, Arch Intern Med 148:1753–1756, 1988.
6. Scott RA, Wilson NM, Ashton HA, et al: Influence of screening on the incidence of ruptured
abdominal aortic aneurysm: 5-year results of a randomized controlled study, Br J Surg
82:1066–1070, 1995.
Fig. 38-9).
7. Lindholt JS, Juul S, Fasting H, et al: Hospital costs and benefits of screening for abdominal
aortic aneurysms. Results from a randomised population screening trial, Eur J Vasc Endovasc
Surg 23:55–60, 2002.
8. Ashton HA, Buxton MJ, Day NE, et al: The Multicentre Aneurysm Screening Study (MASS)
into the effect of abdominal aortic aneurysm screening on mortality in men: a randomised
controlled trial, Lancet 360:1531–1539, 2002.
9. Frydman G, Walker PJ, Summers K, et al: The value of screening in siblings of patients with
abdominal aortic aneurysm, Eur J Vasc Endovasc Surg 26:396–400, 2003.
10. Hirsch AT, Haskal ZJ, Hertzer NR, et al: ACC/AHA 2005 practice guidelines for the
management of patients with peripheral arterial disease (lower extremity, renal,
mesenteric, and abdominal aortic): a collaborative report from the American
Association for Vascular Surgery/Society for Vascular Surgery, Society for Cardiovascular
Angiography and Interventions, Society for Vascular Medicine and Biology, Society
of Interventional Radiology, and the ACC/AHA Task Force on Practice Guidelines
(Writing Committee to Develop Guidelines for the Management of Patients With
Peripheral Arterial Disease): endorsed by the American Association of Cardiovascular
and Pulmonary Rehabilitation; National Heart, Lung, and Blood Institute; Society
for Vascular Nursing; TransAtlantic Inter-Society Consensus; and Vascular Disease
Foundation, Circulation 113:e463–e654, 2006.
11. Screening for abdominal aortic aneurysm: recommendation statement, Ann Intern Med
142:198–202, 2005.
12. Loscalzo ML, Goh DL, Loeys B, et al: Familial thoracic aortic dilation and bicommissural
aortic valve: a prospective analysis of natural history and inheritance, Am J Med Genet A
143A:1960–1967, 2007.
13. Albornoz G, Coady MA, Roberts M, et al: Familial thoracic aortic aneurysms and dissections–
incidence, modes of inheritance, and phenotypic patterns, Ann Thorac Surg 82:1400–1405,
2006.
14. Hiratzka LF, Bakris GL, Beckman JA, et al: 2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/
STS/SVM guidelines for the diagnosis and management of patients with thoracic aortic
disease: a report of the American College of Cardiology Foundation/American Heart
Association Task Force on Practice Guidelines, American Association for Thoracic Surgery,
American College of Radiology, American Stroke Association, Society of Cardiovascular
Anesthesiologists, Society for Cardiovascular Angiography and Interventions, Society of
Interventional Radiology, Society of Thoracic Surgeons, and Society for Vascular Medicine,
Circulation 121:e266–e369, 2010.
15. Cumming MJ, Hall AJ, Burbridge BE: Psoas muscle hematoma secondary to a ruptured
abdominal aortic aneurysm: case report, Can Assoc Radiol J 51:279–280, 2000.
16. Kuhn M, Bonnin RL, Davey MJ, et al: Emergency department ultrasound scanning for
abdominal aortic aneurysm: accessible, accurate, and advantageous, Ann Emerg Med
36:219–223, 2000.
17. Salen P, Melanson S, Buro D: ED screening to identify abdominal aortic aneurysms in
asymptomatic geriatric patients, Am J Emerg Med 21:133–135, 2003.
18. Tayal VS, Graf CD, Gibbs MA: Prospective study of accuracy and outcome of emergency
ultrasound for abdominal aortic aneurysm over two years, Acad Emerg Med 10:867–871,
2003.
19. Lee TY, Korn P, Heller JA, et al: The cost-effectiveness of a “quick-screen” program for
abdominal aortic aneurysms, Surgery 132:399–407, 2002.
20. Lederle FA, Wilson SE, Johnson GR, et al: Variability in measurement of abdominal
aortic aneurysms. Abdominal Aortic Aneurysm Detection and Management Veterans
Administration Cooperative Study Group, J Vasc Surg 21:945–952, 1995.
21. Sprouse LR 2nd, Meier GH 3rd, Lesar CJ, et al: Comparison of abdominal aortic aneurysm
diameter measurements obtained with ultrasound and computed tomography: is there a
difference? J Vasc Surg 38:466–471, 2003 discussion 471–462.
22. Mortality results for randomised controlled trial of early elective surgery or
ultrasonographic surveillance for small abdominal aortic aneurysms. The UK Small
Aneurysm Trial Participants, Lancet 352:1649–1655, 1998.
23. Lederle FA, Wilson SE, Johnson GR, et al: Immediate repair compared with surveillance of
small abdominal aortic aneurysms, N Engl J Med 346:1437–1444, 2002.
24. Cao P, De Rango P, Verzini F, et al: Comparison of surveillance versus aortic endografting for
small aneurysm repair (CAESAR): results from a randomised trial, Eur J Vasc Endovasc Surg
41:13–25, 2011.
25. Teodorescu VJ, Morrissey NJ, Olin JW: Duplex ultrasonography and its impact on providing
endograft surveillance, Mt Sinai J Med 70:364–366, 2003.
26. van Essen JA, Gussenhoven EJ, Blankensteijn JD, et al: Three-dimensional intravascular
ultrasound assessment of abdominal aortic aneurysm necks, J Endovasc Ther 7:380–388,
2000.
27. Leotta DF, Paun M, Beach KW, et al: Measurement of abdominal aortic aneurysms with
three-dimensional ultrasound imaging: preliminary report, J Vasc Surg 33:700–707,
2001.
28. Bendick PJ, Bove PG, Long GW, et al: Efficacy of ultrasound scan contrast agents in the
noninvasive follow-up of aortic stent grafts, J Vasc Surg 37:381–385, 2003.
29. Nagre SB, Taylor SM, Passman MA, et al: Evaluating outcomes of endoleak discrepancies
between computed tomography scan and ultrasound imaging after endovascular
abdominal aneurysm repair, Ann Vasc Surg 25:94–100, 2011.
30. Cantisani V, Ricci P, Grazhdani H, et al: Prospective comparative analysis of colour-Doppler
ultrasound, contrast-enhanced ultrasound, computed tomography and magnetic
resonance in detecting endoleak after endovascular abdominal aortic aneurysm repair,
Eur J Vasc Endovasc Surg 41:186–192, 2011.
31. Chirillo F, Cavallini C, Longhini C, et al: Comparative diagnostic value of transesophageal
echocardiography and retrograde aortography in the evaluation of thoracic aortic
dissection, Am J Cardiol 74:590–595, 1994.
32. Hein PA, Romano VC, Lembcke A, et al: Initial experience with a chest pain protocol using
320-slice volume MDCT, Eur Radiol 19:1148–1155, 2009.
33. Todd GJ, Nowygrod R, Benvenisty A, et al: The accuracy of CT scanning in the diagnosis of
abdominal and thoracoabdominal aortic aneurysms, J Vasc Surg 13:302–310, 1991.
34. Simoni G, Perrone R, Cittadini G Jr, et al: Helical CT for the study of abdominal aortic
aneurysms in patients undergoing conventional surgical repair, Eur J Vasc Endovasc Surg
12:354–358, 1996.
477
CH
38
CliniCAl EvAluATion of AoRTiC AnEuRysms
478
Данная книга находится в списке для перевода на русский язык сайта https://meduniver.com/
35. Posacioglu H, Islamoglu F, Apaydin AZ, et al: Predictive value of conventional computed
tomography in determining proximal extent of abdominal aortic aneurysms and possibility
of infrarenal clamping, Tex Heart Inst J 29:172–175, 2002.
36. Errington ML, Ferguson JM, Gillespie IN, et al: Complete pre-operative imaging
assessment of abdominal aortic aneurysm with spiral CT angiography, Clin Radiol
52:369–377, 1997.
37. Raptopoulos V, Rosen MP, Kent KC, et al: Sequential helical CT angiography of aortoiliac
CH
disease, AJR Am J Roentgenol 166:1347–1354, 1996.
38. Filis KA, Arko FR, Rubin GD, et al: Three-dimensional CT evaluation for endovascular
38
abdominal aortic aneurysm repair. Quantitative assessment of the infrarenal aortic neck,
Acta Chir Belg 103:81–86, 2003.
39. Willmann JK, Wildermuth S, Pfammatter T, et al: Aortoiliac and renal arteries: prospective
intraindividual comparison of contrast-enhanced three-dimensional MR angiography and
multi-detector row CT angiography, Radiology 226:798–811, 2003.
40. Broeders IA, Blankensteijn JD: Preoperative imaging of the aortoiliac anatomy in
endovascular aneurysm surgery, Semin Vasc Surg 12:306–314, 1999.
41. Lutz AM, Willmann JK, Pfammatter T, et al: Evaluation of aortoiliac aneurysm before
endovascular repair: comparison of contrast-enhanced magnetic resonance angiography
with multidetector row computed tomographic angiography with an automated analysis
software tool, J Vasc Surg 37:619–627, 2003.
42. Whitaker SC: Imaging of abdominal aortic aneurysm before and after endoluminal stentgraft repair, Eur J Radiol 39:3–15, 2001.
43. Thurnher SA, Dorffner R, Thurnher MM, et al: Evaluation of abdominal aortic aneurysm
for stent-graft placement: comparison of gadolinium-enhanced MR angiography versus
helical CT angiography and digital subtraction angiography, Radiology 205:341–352,
1997.
44. Pitoulias GA, Donas KP, Schulte S, et al: Two-dimensional versus three-dimensional CT
angiography in analysis of anatomical suitability for stentgraft repair of abdominal aortic
aneurysms, Acta Radiol 52:317–323, 2011.
45. Masuda Y, Takanashi K, Takasu J, et al: Expansion rate of thoracic aortic aneurysms and
influencing factors, Chest 102:461–466, 1992.
46. Quint LE, Francis IR, Williams DM, et al: Evaluation of thoracic aortic disease with the use of
helical CT and multiplanar reconstructions: comparison with surgical findings, Radiology
201:37–41, 1996.
47. Czermak BV, Fraedrich G, Schocke MF, et al: Serial CT volume measurements after
endovascular aortic aneurysm repair, J Endovasc Ther 8:380–389, 2001.
48. Amparo EG, Hoddick WK, Hricak H, et al: Comparison of magnetic resonance imaging and
ultrasonography in the evaluation of abdominal aortic aneurysms, Radiology 154:451–456,
1985.
49. Krinsky GA, Rofsky NM, DeCorato DR, et al: Thoracic aorta: comparison of gadoliniumenhanced three-dimensional MR angiography with conventional MR imaging, Radiology
202:183–193, 1997.
50. Prince MR, Narasimham DL, Stanley JC, et al: Gadolinium-enhanced magnetic resonance
angiography of abdominal aortic aneurysms, J Vasc Surg 21:656–669, 1995.
51. Engellau L, Albrechtsson U, Dahlstrom N, et al: Measurements before endovascular repair
of abdominal aortic aneurysms. MR imaging with MRA vs. angiography and CT, Acta Radiol
44:177–184, 2003.
52. Yamada N, Okita Y, Minatoya K, et al: Preoperative demonstration of the Adamkiewicz artery
by magnetic resonance angiography in patients with descending or thoracoabdominal
aortic aneurysms, Eur J Cardiothorac Surg 18:104–111, 2000.
53. Kudo K, Terae S, Asano T, et al: Anterior spinal artery and artery of Adamkiewicz detected
by using multi-detector row CT, AJNR Am J Neuroradiol 24:13–17, 2003.
54. Yoshioka K, Niinuma H, Ohira A, et al: MR angiography and CT angiography of the artery
of Adamkiewicz: noninvasive preoperative assessment of thoracoabdominal aortic
aneurysm, Radiographics 23:1215–1225, 2003.
55. Cabellon S Jr, Moncrief CL, Pierre DR, et al: Incidence of abdominal aortic aneurysms in
patients with atheromatous arterial disease, Am J Surg 146:575–576, 1983.
56. Ohman EM, Fitzsimons P, Butler F, et al: The value of ultrasonography in the screening for
asymptomatic abdominal aortic aneurysm, Ir Med J 78:127–129, 1985.
57. Twomey A, Twomey E, Wilkins RA, et al: Unrecognised aneurysmal disease in male
hypertensive patients, Int Angiol 5:269–273, 1986.
58. Allen PI, Gourevitch D, McKinley J, et al: Population screening for aortic aneurysms, Lancet
2:736, 1987.
59. Allardice JT, Allwright GJ, Wafula JM, et al: High prevalence of abdominal aortic aneurysm
in men with peripheral vascular disease: screening by ultrasonography, Br J Surg 75:240–
242, 1988.
60. Collin J, Araujo L, Walton J, et al: Oxford screening programme for abdominal aortic
aneurysm in men aged 65 to 74 years, Lancet 2:613–615, 1988.
61. Shapira OM, Pasik S, Wassermann JP, et al: Ultrasound screening for abdominal aortic
aneurysms in patients with atherosclerotic peripheral vascular disease, J Cardiovasc Surg
(Torino) 31:170–172, 1990.
62. Andersson AP, Ellitsgaard N, Jorgensen B, et al: Screening for abdominal aortic aneurysm in
295 outpatients with intermittent claudication, Vasc Surg 25:516–520, 1991.
63. Spiridonov AA, Omirov ShR: Selective screening for abdominal aortic aneur ysms by using the
clinical examination and ultrasonic scanning, Grud Serdechnososudistaia Khir 33–36, 1992.
64. MacSweeney ST, O'Meara M, Alexander C, et al: High prevalence of unsuspected abdominal
aortic aneurysm in patients with confirmed symptomatic peripheral or cerebral arterial
disease, Br J Surg 80:582–584, 1993.
65. Karanjia PN, Madden KP, Lobner S: Coexistence of abdominal aortic aneurysm in patients
with carotid stenosis, Stroke 25:627–630, 1994.
66. Molnar LJ, Langer B, Serro-Azul J, et al: Prevalence of intraabdominal aneurysm in elderly
patients, Rev Assoc Med Bras 41:43–46, 1995.
67. al-Zahrani HA, Rawas M, Maimani A, et al: Screening for abdominal aortic aneurysm in the
Jeddah area, western Saudi Arabia, Cardiovasc Surg 4:87–92, 1996.
68. Arnell TD, de Virgilio C, Donayre C, et al: Abdominal aortic aneurysm screening in elderly
males with atherosclerosis: the value of physical exam, Am Surg 62:861–864, 1996.
69. Fink HA, Lederle FA, Roth CS, et al: The accuracy of physical examination to detect
abdominal aortic aneurysm, Arch Intern Med 160:833–836, 2000.
CHAPTER
39 Surgical Treatment of
Abdominal Aortic Aneurysms
David H. Stone, Jack L. Cronenwett
Abdominal aortic aneurysms (AAAs) remain a leading cause of
death in the elderly. In the United States, ruptured AAAs are the
15th leading cause of death overall and the 10th leading cause
of death in men older than age 55.
patients with ruptured AAAs die after reaching a hospital, but without operation.
40% to 50%,
for AAA rupture.
changed over the past 20 years despite improvements in operative
technique and perioperative critical care management that have
reduced the elective surgical mortality rate to less than 5% in most
series.
burden on overall healthcare costs. One report estimated that as
much as $50 million and 2000 lives could have been saved in 1 year
if AAAs had been repaired prior to rupture.11 Another study showed
that emergency operations for AAAs resulted in a mean financial
loss to the hospital of $24,655 per patient.
cant implications in an era of healthcare cost containment. For all
these reasons, AAAs remain a central focus for vascular surgeons
and an important healthcare problem for all physicians.
2
When combined with an operative mortality rate of
3–7
this results in an overall mortality rate of 80% to 90%
8–10
Unfortunately, this high mortality rate has not
3
Ruptured aneurysms also impose a substantial financial
1
In addition, 30% to 40% of
12
These data have signifi-
Definition
Most aortic aneurysms are true aneurysms involving all layers of
the aortic wall and are infrarenal in location. As shown by Pierce
et al.,13 normal aortic diameter gradually decreases from the thorax
(28 mm in men) to the infrarenal location (20 mm in men). At all
anatomical levels, normal aortic diameter is approximately 2 mm
larger in men than in women and increases with age and increased
body surface area.
is 2 cm, using a 3-cm definition for an infrarenal AAA has been
recommended, without the need to consider a more complicated
definition based on factors such as gender or body surface area.
Although such definitions are useful for large patient groups, in
clinical practice with individual patients, defining an aneurysm
based on a 50% or greater diameter enlargement compared with
the adjacent nonaneurysmal aorta has been recommended.14 This
is particularly true for patients with unusually small arteries, in
whom even a 2.5-cm local dilation of the infrarenal aorta might
be aneurysmal if the adjacent aorta were only 1.5 cm in diameter.
13
Because the average infrarenal aortic diameter
Decision Making for Elective Abdominal
Aortic Aneurysm Repair
The choice between observation and elective surgical repair of
an AAA for an individual patient at any given point should take
into account the (1) rupture risk under observation, (2) operative risk of repair, (3) patient's life expectancy, and (4) personal
preferences of the patient.
vided substantial information to assist with this decision-making
process. The U.K. Small Aneurysm Trial was the first randomized
trial to compare early surgery with surveillance of 4- to 5.5-cm
diameter AAAs in 1090 patients aged 60 to 76.
ing surveillance underwent repeat ultrasound every 6 months for
AAAs 4 to 4.9 in diameter cm, and every 3 months for those 5 to
5.5 cm. If AAA diameter exceeded 5.5 cm, the expansion rate was
more than 1 cm/yr, the AAA became tender, or repair of an iliac or
thoracic aneurysm was necessary, elective surgical repair was recommended. At the initial report in 1998, after a mean 4.6 years’ follow-up, there was no difference in survival between the two groups.
After 3 years, patients who had undergone early surgery had better
15,16
Two randomized trials have pro-
17
Those undergo-
late survival, but the difference was not significant. It was notable
that more than 60% of patients randomized to surveillance eventually underwent surgery at a median time of 2.9 years. Rupture risk
among those undergoing careful surveillance was 1% per year.
In 2002, the U.K. trial participants published results of long-term
follow-up.
early surgery group (7.2% improved survival). However, the proportion of deaths due to rupture of an unrepaired AAA was low (6%).
The early surgery group had a higher rate of smoking cessation,
which may have contributed to a reduction in overall mortality. An
additional 12% of surveillance patients underwent surgical repair
during extended follow-up to bring the total to 74%. Fatal rupture
occurred in only 5% of men but 14% of women in the surveillance
group. Risk of rupture was more than four times higher for women
than men. This prompted participants to recommend a lowerdiameter threshold for elective AAA repair in women.
ducted at the U.S. Department of Veterans Affairs (VA) hospitals
was published in 2002.
aged 50 to 79 with AAAs 4 to 5.4 cm in diameter were randomized to either surveillance or early surgery. Surveillance entailed
ultrasound or computed tomography (CT) scan every 6 months,
with elective surgery for expansion to 5.5 cm, expansion of greater
than 0.7 cm in 6 months or greater than 1 cm in 1 year, or development of symptoms attributable to the AAA. Computed tomography
was used for initial evaluation, with AAA diameter defined as the
maximal cross-sectional measurement in any plane that was perpendicular to the aorta. Ultrasound was used for the majority of
surveillance visits, but CT was used when the diameter reached
5.3 cm. Patients with severe heart or lung disease were excluded,
as were those who were not likely to comply with surveillance. As
in the U.K. trial, there was no survival difference between the two
strategies after a mean follow-up of 4.9 years. Similarly, more than
60% of patients in the surveillance arm underwent repair. Initial
AAA diameter predicted subsequent surgical repair in the surveillance group; 27% of those with AAAs initially 4 to 4.4 cm underwent
repair during follow-up, compared with 53% of those with 4.5 to
4.9 cm, and 81% of those with 5- to 5.4-cm diameter AAAs. Operative
mortality was 2.7% in the early surgery group and 2.1% in the surveillance group. Rupture risk in those undergoing surveillance was
0.6% per year. This trial confirmed the results of the U.K. trial, demonstrating lack of benefit of early surgery for AAAs 4 to 5.5 cm, even
if operative mortality is low. Compliance with surveillance was
high in both trials. More recently, Ouriel et al. reported results of 728
patients who were randomized to either ultrasound surveillance
or early endovascular AAA repair (EVAR). Mean follow-up of 20 ±
12 months demonstrated no difference in AAA rupture, aneurysmrelated death, or overall mortality between groups.
it is generally safe to wait for AAA diameter to reach 5.5 cm before
performing surgery in selected men who are compliant with surveillance, even if their operative mortality is predicted to be low even
in the endovascular era. However, compliance in these carefully
monitored trials of selected patients was high. In another VA population, Valentine et al.21 reported that 32 of 101 patients undergoing
AAA surveillance were noncompliant despite several appointment
reminders, and 3 or 4 of these 32 patients experienced rupture.
Additionally, the increased rupture risk for women seen in the U.K.
trial highlights the need to individualize treatment on the basis of
a careful assessment of individual patient characteristics (rupture
risk, operative risk, life expectancy, and patient preferences).
18
At 8 years, there was a small survival advantage in the
The Aneurysm Detection and Management (ADAM) study con-
19
In this trial, 1163 veterans (99% male)
20
Taken together, these two large randomized studies indicate that
479
480
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Elective Operative Risk
As expected, considerable variation in operative risk occurs
among individual patients and depends on specific risk factors.
A meta-analysis by Steyerberg et al.22 identified seven prognostic
factors that were independently predictive of operative mortality
CH
with elective AAA repair and calculated the relative risk for these
39
factors (
operative mortality were renal dysfunction (creatinine (Cr) >
dL), congestive heart failure (CHF) (cardiogenic pulmonary
edema, jugular vein distension, or the presence of a gallop rhythm),
and ischemic changes on resting electrocardiogram (ECG; ST
depression >
corrected for the highly associated comorbidities of cardiac, renal,
and pulmonary dysfunction (mortality increased only 1.5-fold per
decade). This explains the excellent results reported in multiple
series in which selected octogenarians have undergone elective
AAA repair, with mortality comparable to younger patients.
clinical prediction rule to estimate the operative mortality for individual patients undergoing elective AAA repair (
scoring system takes into account the seven independent risk factors plus the average overall elective mortality for a specific center.
To demonstrate the impact of the risk factors on a hypothetical
patient, it can be seen that the predicted operative mortality for
a 70-year-old man in a center with an average operative mortality
of 5% could range from 2% if no risk factors were present to more
than 40% if cardiac, renal, and pulmonary comorbidities were all
present. Obviously this would have a substantial impact on the
decision to perform elective AAA repair. A similar Bayesian model
for perioperative cardiac risk assessment in vascular patients has
been reported by L'Italien et al.,24 which demonstrated the added
predictive value of dipyridamole- thallium studies in patients with
intermediate risk for cardiac death. This study also demonstrated
the protective effect of coronary artery bypass surgery within the
previous 5 years, which reduced the risk of myocardial infarction
(MI) or death following AAA repair by 2.2-fold. Although this type
of statistical modeling cannot substitute for experienced clinical
judgment, it helps identify high-risk patients who might benefit
from further evaluation, risk factor reduction, or medical management instead of surgery if AAA rupture risk is not high.
group that renal failure is the strongest predictor of mortality, with a
four- to ninefold increased mortality risk. Cardiac disease (a history
of either coronary artery disease [CAD], CHF, or prior MI) was associated with a 2.6- to 5.3-fold greater operative mortality risk. Older
age and female gender appeared to be associated with increased
risk, but the evidence was not as strong. Valuable data regarding
predictors of operative risk have been generated by prospective
trials. In the Canadian Aneurysm Study, overall operative mortality
*Indicates relative risk compared with patients without that risk factor.
CHF, congestive heart failure; Cr, creatinine; ECG, electrocardiogram.
From Steyerberg EW, Kievit J, de Mol Van Otterloo JC, et al: Perioperative mortality of elective
abdominal aortic aneurysm surgery. A clinical prediction rule based on literature and individual
patient data. Arch Intern Med 155:1998–2004, 1995.
Table 39-1). The most important risk factors for increased
2 mm). Age had a limited effect on mortality when
On the basis of their analysis, Steyerberg et al.22 developed a
Table 39-2). This
The review of Hallin et al.5 supports the findings of Steyerberg's
Independent Risk Factors for Operative
TABLE 39-1
Mortality After Elective Abdominal Aortic
Aneurysm Repair
RISK FACTOR
1.8 mg/dL 3.3 1.5-7.5
Cr >
CHF 2.3 1.1-5.2
ECG ischemia 2.2 1-5.1
Pulmonary dysfunction 1.9 1-3.8
Older age (per decade) 1.5 1.2-1.8
Female gender 1.5 0.7-3
ODDS RATIO*
22
95% CONFIDENCE
INTERVAL
1.8 mg/
23
TABLE 39-2
1. Surgeon-specific average operative mortality:
Mortality (%): 3 4 5 6 8 12
Score: − 5 − 2 0 + 2 + 5 + 10 ____
2. Individual patient risk factors:
Age (yrs): 60 70 80
Score: − 4 0 + 4
Gender: Female Male
Score: + 4 0
Cardiac comorbidity: MI CHF ECG Ischemia
Score: + 3 + 8 + 8
Renal comorbidity: Cr >1.8 mg/dL
Score: + 12
Pulmonary comorbidity: COPD, dyspnea
Score: + 7
3. Estimated individual surgical mortality Total Score: _____
ToTal Score: –5 0 5 10 15 20 25 30 35 40
MorTaliTy (%): 1 2 3 5 8 12 19 28 39 51
Based on total score from sum of scores for each risk factor (line 2), including surgeon-specific
average mortality for elective AAA repair (line 1), estimate patient-specific mortality from the
table (line 3).
AAA, abdominal aortic aneurysm; CHF, congestive heart failure; COPD, chronic obstructive
pulmonary disease; Cr, creatinine; ECG, electrocardiogram; MI, myocardial infarction.
From Steyerberg EW, Kievit J, de Mol Van Otterloo JC, et al. Perioperative mortality of elective
abdominal aortic aneurysm surgery. A clinical prediction rule based on literature and individual
patient data. Arch Intern Med 155:1998–2004, 1995.
was 4.8%.
Predicting Operative Mortality After Elective
Abdominal Aortic Aneurysm Repair
22
25
Preoperative predictors of death were ECG evidence
of ischemia, chronic pulmonary disease, and renal insufficiency.
The randomized U.K. Small Aneurysm Trial found older age, lower
forced expiratory volume in 1 second (FEV1), and higher Cr to be
associated with mortality on univariate analysis.
26
With multivariate
analysis, the effect of age was diminished, whereas renal disease
and pulmonary disease remained strong predictors of operative
mortality. The predicted mortality ranged from 2.7% for younger
patients with below average Cr and above average FEV
in older patients with above average Cr and below average FEV
The U.K. trialists noted that the Steyerberg prediction rule did not
to 7.8%
1
1
work well for the U.K. trial patients. However, they did not gather
information on a history of CHF (one of the strongest predictors
in Steyerberg's analysis) in the randomized trial. Female gender
has also been found to be associated with higher operative risk in
several population-based studies using administrative data.
3,22,27,28
However, these databases may suffer from inaccurate coding of
comorbidities and thereby lack of ability to fully adjust for comorbid conditions.
operative mortality in prospective trials.
29
Gender has not been found to be associated with
26,30
More recently, a study by Beck et al. from the Vascular Study
Group of New England assessed risk factors associated with 1-year
mortality following open AAA repair and EVAR. In this study, 1387
consecutive patients between 2003 and 2007 underwent elective AAA repair, including 748 who underwent open repair and
639 who underwent EVAR. Consistent with other studies, factors
associated independently with 1-year mortality following open
AAA repair included age (>
nary disease (COPD), chronic renal insufficiency (Cr >
70 years), chronic obstructive pulmo-
1.8 mg/dL)
and suprarenal aortic clamp site. Likewise, factors associated with
1-year mortality following EVAR included CHF and AAA diameter.
One-year mortality correlated linearly with the number of risk factors present, and accordingly should be factored into decision
making when considering elective AAA repair.
31
Life Expectancy
Assessment of life expectancy is crucial to determine whether an
individual patient will benefit from prophylactic repair of an AAA.
Many patients with AAAs have been long-term smokers. Most AAA
.
patients also have extensive comorbid disease, particularly CAD,
COPD, hypertension, hyperlipidemia, cerebrovascular disease, and
32–37
cancer.
Many of these chronic conditions increase operative
risk, as noted earlier. In addition, these factors impact life expectancy. Patients who survive elective AAA repair have a reduced
life expectancy compared to age- and gender-matched popula-
38–40
tions.
In 2001, Norman et al.41 reviewed 32 publications over
20 years that described long-term survival after AAA repair. They
found that the mean 5-year survival after AAA repair was 70%,
compared with 80% in the age- and gender-matched population
without AAA. Predictors of late death after successful AAA repair
include age, cardiac disease, chronic pulmonary disease, renal
insufficiency, and continued smoking.
38,42,43
The U.K. trialists found
(after adjustment for age, gender, and AAA diameter but not cardiac disease) that both FEV
cotinine) predicted late death.
and current smoking status (plasma
1
43
Surgical Decision Making
In patients with symptomatic AAAs, operative repair is nearly always
appropriate because of the high mortality associated with rupture
or thrombosis and the high likelihood of limb loss associated with
peripheral embolism. Occasionally, high-risk patients or those with
short life expectancies may choose to forego emergency repair
of symptomatic AAAs, but in general, surgical decision making
for symptomatic AAAs is straightforward. A contemporary analysis of outcomes of symptomatic AAAs by De Martino et al. from
the Vascular Study Group of New England recently assessed 2386
AAA repairs in whom 1959 were elective, 156 were symptomatic,
and 271 were ruptured. EVAR was successfully performed in 945
elective patients, 60 symptomatic patients, and 33 ruptured AAA
patients, respectively. Hospital mortality was 1.7% for elective AAA,
compared to 1.3% for the symptomatic cohort. One- and 4-year
survival was determined to be 83% and 68%, respectively, among
the symptomatic group, which compared favorably to the elective
group with 89% and 73% 1- and 4-year survival.
For those with asymptomatic AAAs, randomized trials have provided assurance that the typical male patient can generally be
safely monitored with careful ultrasound surveillance until the AAA
reaches 5.5 cm, at which time elective repair can be performed.
However, decision analyses and cost-effectiveness modeling have
previously demonstrated that individual patient rupture risk, operative risk, and life expectancy have to be considered to determine the optimal threshold for intervention.
and ADAM trials excluded patients who were considered “unfit”
for repair, highlighting the fact that those with high operative
risk and short life expectancy should have a threshold diameter
greater than 5.5 cm. In the U.K. trial, the rupture risk for women
was 4.5-fold higher than for men, prompting the authors to recommend a lower threshold for women than men, so it seems logical to consider other factors that may make rupture more likely
during surveillance as well. In both randomized trials, 60% to 75%
of patients undergoing surveillance eventually underwent AAA
19,47
repair.
In the U.K. trial, 81% of those with initial diameters 5 to
5.4 cm eventually underwent repair. Clearly, for many patients with
this size AAA, the question is not whether to perform AAA repair
but when. Therefore, in patients with AAA diameters approaching
5.5 cm whose life expectancy is expected to be more than 5 years
and whose operative risk is estimated to be low, the patient should
be informed that AAA repair would likely be required within the
next few years. This subgroup of patients could be offered surgery
at a time when it is convenient for them, with the understanding
that waiting for expansion to 5.5 cm has little risk. In these cases,
patient preference should weigh heavily in the decision-making
process. For those with multiple risk factors for rupture, long life
expectancy, and low operative risk, it would seem prudent to recommend AAA repair at less than 5.5 cm. Additionally, the ability of
the patient to comply with careful surveillance should be considered. Although the recent randomized trials have provided a great
deal of information to guide decision making, clinicians should
44
15,16,45,46
Both the U.K.
not adopt a one-size-fits-all policy for treating patients with AAA.
Moreover, with a progressively aging population in mind, qualityof-life assessments should likely be factored into decision-making
analyses as well.
Preoperative Assessment
Patient Evaluation
A careful history, physical examination, and basic laboratory data
are the most important factors for estimating perioperative risk and
subsequent life expectancy. These factors may not only influence
the decision to perform elective AAA repair, but they may focus
preoperative management to reduce modifiable risk. Assessments
of activity level, stamina, and stability of health are important and
can be translated into metabolic equivalents to help assess both
cardiac and pulmonary risks.
predictor of operative mortality,
nary function studies as well as room air arterial blood gas measurement in patients who have apparent pulmonary disease. In
some cases, preoperative treatment with bronchodilators and pulmonary toilet can reduce operative risk.
pulmonary risk may substantially reduce life expectancy, and in
these patients, formal pulmonary consultation may be helpful to
estimate survival. Serum Cr is one of the most important predictors
of operative mortality
25
diseases such as malignancy on expected survival should also be
carefully considered.
It is well established that patients with AAAs have a high prevalence of CAD. By performing routine preoperative coronary arteriography at the Cleveland Clinic in 1979, Hertzer et al.50 reported
that only 6% of patients with AAAs had normal arteries; 29% had
mild to moderate CAD, 29% had advanced compensated CAD, 31%
had severe correctable CAD, and 5% had severe uncorrectable
CAD. Furthermore, this study established that clinical prediction of
the severity of CAD was imperfect because 18% of patients without
clinically apparent CAD had severe correctable CAD on arteriography, compared with 44% of patients whose CAD was clinically
apparent. This pivotal study has led to intense efforts to identify risk
factors and algorithms that more accurately predict the presence
of severe CAD that would justify its correction before AAA repair,
or would lead to avoiding AAA repair. A number of clinical parameters such as angina, history of MI, Q-wave on ECG, ventricular
arrhythmia, CHF, diabetes, and increasing age have been reported
to increase the risk of postoperative cardiac events.51 Various combinations of these risk factors have been used to generate prediction algorithms for perioperative cardiac morbidity.48 In general,
these algorithms identify low-risk, high-risk, or intermediate-risk
patients. For high-risk patients, such as those with unstable angina,
more sophisticated cardiac evaluation is required, whereas lowrisk patients may undergo elective AAA repair without further testing. For intermediate-risk patients, who comprise the vast majority
with AAAs, decision making is more difficult and may be assisted
by additional cardiac testing.
Aneurysm Evaluation
Most surgeons recommend a preoperative imaging study using
CT scanning, magnetic resonance imaging or angiography (MRI/
MRA), or arteriography. Contrast-enhanced CT appears to be the
most useful study for preoperative AAA evaluation when considering information obtained, invasiveness, and cost (also see
Chapter 14). This is particularly true for spiral CT scanning, with
thin “slices” in the region of interest. This allows not only accurate
size measurements but also accurate definition of the relationship
of an AAA to visceral and renal arteries. Furthermore, CT scanning
aids in identifying venous anatomical anomalies (e.g., retroaortic
left renal vein, duplicated vena cava) or renal abnormalities (e.g.,
horseshoe or pelvic kidney) that would influence operative techniques and approach. Computed tomography is the technique of
choice to identify suspected inflammatory aneurysms and may
48
Because COPD is an independent
26,30
it should be assessed by pulmo-
49
In more extreme cases,
and must be assessed. The impact of other
51
481
CH
39
SuRgiCAl TREATmEnT of AbdominAl AoRTiC AnEuRySmS
482
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reveal unsuspected abdominal pathology such as associated
malignancy or gallbladder disease. In centers with experience
with these techniques, CT angiography has made percutaneous
intraarterial angiography unnecessary in the vast majority of AAA
patients. Moreover, in the EVAR era, CT is vital for case planning
and accurate detailed anatomical assessment of aortic neck anat-
CH
omy, iliac artery anatomy and tortuosity, and perirenal mural throm-
39
bus burden among other factors. In addition, three-dimensional
(ED) modeling of contemporary CT scanning is useful prior to
EVAR as well as open AAA repair and has largely supplanted the
role of conventional angiography.
Magnetic resonance imaging is comparable with CT in terms
of AAA measurement accuracy and other preoperative planning
issues (also see Chapter 13). It avoids intravenous contrast, which
may represent an advantage over CT for some patients. Because it
is more expensive and time consuming, it also is not as widely used
as CT. When MRA is included with this technique, however, it can
significantly increase the value in patients where additional imaging would otherwise be required.
Surgical Treatment
For the past 40 years, AAAs have been repaired using the technique
of endoaneurysmorrhaphy with intraluminal graft placement, as
described by Creech.
section on transperitoneal approach. Development of this technique was based in part on the failure of previous “nonresective”
operations now of only historical interest, including aneurysm
ligation, wrapping, and attempts at inducing aneurysm thrombosis that yielded uniformly dismal results. Abdominal aortic
aneurysm thrombosis by iliac ligation combined with axillobifemoral bypass enjoyed a brief resurgence in popularity for high-risk
patients but demonstrated a high complication rate, including
late aneurysm rupture, and an operative mortality rate comparable with conventional repair in similar patients.
technique was similarly abandoned. As an alternative to standard
open AAA repair, Shah and Leather et al.58 proposed exclusion
of an AAA with bypass to reduce operative blood loss. However,
this group has recently published long-term follow-up and no longer recommends this procedure owing to persistent flow in the
excluded AAA sac and rupture in rare cases.
to reduce the invasiveness of open AAA repair, the use of laparoscopy as an adjunct has been suggested to assist AAA repair. This
approach uses laparoscopic techniques to dissect the aneurysm
neck and iliac arteries, followed by a standard endoaneurysmorrhaphy through a mini-laparotomy. Cohen et al.60 have reported
their results in 20 patients to demonstrate the feasibility of this
approach, but a clear benefit has not been shown; intraoperative,
intensive care unit (ICU), and total hospital duration were comparable with conventional AAA repair. Further experience with this
technique may identify a subgroup of patients for whom a laparoscopic-assisted AAA repair is advantageous.
EVAR (see Chapter 40) repair was introduced by Parodi in
1991 and has rapidly gained in popularity in the United States
after reports of clinical trials and subsequent U.S. Food and Drug
Administration (FDA) approval.
been shown to reduce operative morbidity, mortality, length of stay,
and disability compared with open repair.
shorter after endovascular repair than open repair,
vascular repair may not be as durable.
surveillance is required after endovascular repair, along with reintervention or conversion to open repair in some. There appears
to be a small ongoing risk of rupture after endografting as well.
Decision analysis suggests that there is little difference in outcome
between open and endovascular repair for most patients.
endovascular AAA repair is usually recommended for those with
good anatomy for EVAR or those with marginal anatomy but high
operative risk for open surgery. Open surgery may be preferred
for younger, healthier patients in whom there is little difference in
operative risk between the two strategies, and for whom long-term
52
This procedure is described later in the
53–57
59
In another attempt
61
Endovascular AAA repair has
62–65
Recovery time is
63,66
67–74
Frequent and lifelong
Thus this
but endo-
72
However,
durability is a concern, although contemporary stent grafts appear
to have improved durability from their initial constructs and are
now recommended for most patients with acceptable anatomy
(see Chapter 40).
To date, there are several important randomized trials comparing open AAA repair with endovascular repair. Specifically, in the
EVAR I and DREAM trials, patients were randomized to either open
repair or EVAR. The EVAR I study demonstrated a 3% lower initial
mortality associated with endovascular treatment, with a persistent associated reduction in AAA-related death at 4 years. However,
there was no overall improvement in all-cause mortality between
groups. Likewise, the DREAM trial demonstrated an operative mortality advantage associated with EVAR compared to open surgical
repair, but 1-year survival was similar between groups. The EVAR
II study randomized patients unfit for open AAA repair to either
EVAR or no surgical therapy. This trial failed to demonstrate a
survival advantage for the EVAR treatment group compared to
the no treatment group. It should be noted, however, that most
ruptures in the EVAR group occurred during a prolonged delay
before surgery, making the results in this group appear worse. In
addition, 27% of patients in EVAR II crossed over from the no treatment group to the EVAR group, potentially limiting the study's
findings.
71,75–77
Likewise, the VA Open vs. Endovascular AAA repair
(OVER) study randomized patients to either open AAA repair or
EVAR. Results demonstrated diminished perioperative mortality in
the EVAR group compared to the open repair group (0.5% vs. 3.0%).
However, there was no observed difference in mortality at 2 years
between groups. This study also demonstrated diminished median
procedure times, blood loss, transfusion requirement, duration of
mechanical ventilation, hospital length of stay, and ICU length of
stay in the EVAR group.
78
These trials illustrate many of the advantages of EVAR therapy or
open surgery. However, the ultimate treatment must be individually
tailored to specific patients, especially those with high associated
surgical risk. Ongoing rapid advances in stent graft technology will
have to be considered in the future as device applicability and
accompanying morbidity change.
Perioperative Management
Preoperative intravenous antibiotics are administered to reduce
the risk of prosthetic graft infection.
intraarterial pressure recording, and Foley catheter monitoring
of urine output are routine. For patients with significant cardiac
disease, pulmonary artery catheters are frequently used to guide
volume replacement and vasodilator or inotropic drug therapy,
both intraoperatively and in the early postoperative period. Mixed
venous oxygen tension measurement, available with these catheters, can provide an additional estimate of global circulatory function. Transesophageal echocardiography (TEE) can be useful in
certain patients to monitor ventricular volume and cardiac wall
motion abnormalities and to guide fluid administration and use
of vasoactive drugs. Despite the frequent use of pulmonary artery
catheters, studies examining their use during AAA surgery have
not demonstrated added value.
usually excluded high-risk patients who are most likely to benefit
from such monitoring. These techniques are not without risk, so
selective use is probably more appropriate than routine application.
The volume of blood lost during AAA repair often requires
blood replacement. Therefore, intraoperative autotransfusion as
well as preoperative autologous blood donation has become
popular, primarily to avoid the infection risk associated with
allogeneic transfusion. Studies of the cost-effectiveness of such
procedures, however, question their routine use.
blood donation is less important for elderly patients in whom
life expectancy is shorter than the usual time for development
of transfusion-associated viral illness. Autologous blood donation does not appear to be cost-effective in elderly cardiovascular patients, because the allogenic blood pool has become safer
and the transfusion requirement for elective AAA repairs lower.
79
Ample intravenous access,
80,81
However, these studies have
82–84
Autologous
82
Intraoperative autotransfusion during AAA repair is widely used
because of the documented safety of this technique.85 Because it
is usually difficult to predict the volume of blood loss during AAA
repair, most surgeons employ autotransfusion in case blood loss
becomes extensive. Optimizing oxygen delivery to patients with
reduced cardiac output by maintaining an adequate hematocrit
appears beneficial in patients undergoing AAA repair. One study
has shown that a postoperative hematocrit of less than 28% was
associated with significant cardiac morbidity in vascular surgery
patients.
86
Maintenance of normal body temperature during aortic surgery
is important to prevent coagulopathy, allow extubation, and maintain normal metabolic function. In a review of patients undergoing elective AAA repair, Bush et al.87 noted significantly more organ
dysfunction (53% vs. 29%) and higher mortality (12% vs. 1.5%) in
hypothermic patients (temperature <
34.5 °C) compared with normothermic patients. The only predictor of intraoperative hypothermia was female gender, whereas prolonged hypothermia was
related to initial hypothermia, indicating the difficulty in rewarming cold patients. A recent randomized trial found significantly
reduced cardiac morbidity (1.4% vs. 6.3%) in patients who were
normothermic (36.7 °C) rather than hypothermic (35.4 °C) intraoperatively.
88
To prevent hypothermia, a recirculating warm forced-air
blanket should be placed in contact with the patient, and intravenous fluids, including any blood returned from an autotransfusion
device, should be warmed before administration.
The role of ischemic preconditioning in lowering the incidence
of perioperative MI during open AAA repair remains undefined,
although there are data to support its potential benefit. In the largest study to date, Ali et al. randomized 82 patients undergoing elective open AAA repair to receive remote ischemic preconditioning
or not. The technique involves sequential clamping of each common iliac artery (CIA) for 10 minutes, followed by 10 minutes of
respective reperfusion. The authors demonstrated that patients
undergoing remote ischemic preconditioning had both diminished rates of postoperative MI and diminished critical care length
of stay compared to the control groups.
89
Anesthesia
Nearly all patients undergo general anesthesia for AAA repair.
Supplemental use of continuous epidural anesthesia, begun immediately preoperatively and continued for postoperative pain control, is increasing in popularity.
level of general anesthesia to be maintained while controlling pain
through the epidural blockade. Additional benefits may include a
reduction in the sympathetic catecholamine stress response, which
might decrease cardiac complications. One randomized trial comparing general anesthesia with combined general and epidural
anesthesia demonstrated decreased deaths, cardiac events, infection, and overall complications.
observed in another randomized trial,
of perioperative management and patient selection may determine the impact of epidural anesthesia. Furthermore, it is possible
that the major benefit of epidural anesthesia accrues in the postoperative period rather than intraoperatively.
Perioperative β-adrenergic blockade remains somewhat more
controversial, given recent findings of randomized controlled
94
trials.
Earlier studies by Pasternack et al.95 demonstrated that
patients who underwent vascular surgery and received metoprolol immediately before operation had significantly lower heart
rates and less intraoperative myocardial ischemia than untreated
controls. Mangano et al.96 performed the first randomized
placebo-controlled trial to assess the effect of atenolol (given intravenously immediately before and after surgery and orally during
that hospitalization) in patients at risk for CAD who underwent
noncardiac surgery. A significant reduction in mortality extending 2 years after discharge was observed in the atenolol-treated
patients (3% vs. 14% 1-year mortality) because of reduction in
death from cardiac causes. In a separate analysis, they noted that
90
This technique allows a lighter
91
These benefits, however, were not
92
suggesting that the details
93
atenolol-treated patients had a 50% lower incidence of myocardial ischemia during the first 48 hours after surgery and a 40%
lower incidence during postoperative days 0 to 7.
97
Patients with
perioperative myocardial ischemia were significantly more likely
to die within 2 years after surgery. Poldermans et al.98 performed
a randomized trial of perioperative β-blockade with bisoprolol in
patients with abnormal dobutamine echocardiograms undergoing
aortic or lower-extremity arterial reconstruction. They found that
perioperative cardiac death was significantly reduced from 17%
(placebo) to 3% (bisoprolol). Additionally, nonfatal MI occurred
in 17% of those given placebo but in none of those given bisoprolol.
A subsequent publication from the same authors demonstrated
that during a mean follow-up of 22 months, cardiac events were
significantly lower in those who had received perioperative
β-blockade (12% vs. 32%).
99
More recently, however, results from the POISE trial, a randomized controlled trial reflecting 190 hospitals, 23 countries, and an
enrollment of 8351 patients, provided different results. This study
compared the effects of perioperative extended release metoprolol succinate with a limited titration scheme to placebo among
patients undergoing noncardiac surgery. Results demonstrated
that there was a significant reduction in the composite endpoint of cardiovascular death, nonfatal MI, and nonfatal cardiac
arrest among patients receiving perioperative β-blocker therapy.
However, the study also revealed that there were more deaths and
strokes among the treated group compared to placebo.
94
Although
these findings seemingly conflict, perioperative β-blocker use is
valuable when titrated to heart rate, but not when applied at initial
high dose or without respect to the patient's hemodynamics.
100
Given this knowledge, it has been suggested that β-blockers
are underused, likely because of fears about use in patients with
COPD or prior heart failure. However, chronic β-blocker usage
is now known to improve outcomes in patients with heart failure.
101,102
Additionally, Gottlieb et al.
101
demonstrated that COPD
should not be considered a contraindication for β-blockade.
They found a 40% reduction in risk of death after MI in patients
with COPD who were taking β-blockers compared with those who
were not. In Mangano's trial, the only exclusion criteria were preexisting ECG abnormalities that would preclude detection of new
ischemic events. β-Blockers were withheld during the trial only for
a heart rate of less than 55 beats/min, systolic blood pressure less
than 100 mmHg, acute bronchospasm, current evidence of CHF,
or third-degree heart block. The weight of evidence supports routine
use of β-blockers for nearly all patients undergoing AAA repair.
Antiplatelet use remains common in this patient cohort,
concordant with American College of Cardiology/American
Heart Association (ACC/AHA) guidelines for noncardiac surgery.
Associated bleeding risk with such agents, including aspirin
and clopidogrel, remains controversial. In a recent study by the
Vascular Study Group of New England, however, preoperative
antiplatelet use (aspirin alone, clopidogrel alone, combined dual
therapy) was not significantly associated with increased serious
bleeding complications, measured as reoperation for bleeding
across a spectrum of commonly performed vascular procedures
including EVAR, open AAA repair, carotid endarterectomy, and
lower- extremity bypass.
103
Choice of Incision
Abdominal aortic aneurysm repair can be accomplished
through an anterior transperitoneal incision (midline or transverse;
Fig. 39-1) or through a retroperitoneal approach (Fig. 39-2) .
Midline transperitoneal incisions can be performed rapidly and
provide wide access to the abdomen, but they may be associated
with more pulmonary complications due to postoperative splinting from upper abdominal pain. Transverse abdominal incisions
just above or below the umbilicus require more time to open and
close, but may be associated with fewer pulmonary complications
and late incisional hernias, although this has not yet been proven.
Retroperitoneal incisions, from the lateral rectus margin extending
483
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39
SuRgiCAl TREATmEnT of AbdominAl AoRTiC AnEuRySmS
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FIGURE 391 Transperitoneal abdominal aortic aneurysm (AAA)
exposure, vascular clamps in place, incising the aneurysm.
into the 10th or 11th intercostal space, afford good exposure of
both the infrarenal and suprarenal aorta, but limit exposure of the
contralateral renal and iliac arteries. In addition, this exposure does
not allow access to intraabdominal organs unless the peritoneum
is purposely opened. The left retroperitoneal approach is usually
favored over the right for exposure of the upper abdominal aorta
because the spleen is easier to mobilize and retract than the liver.
The right retroperitoneal approach is used when specific abdominal problems, such as a stoma, preclude the left-sided approach.
In recent years, the left retroperitoneal approach has enjoyed
a resurgence in popularity owing to suggestions that pulmonary
morbidity, ileus, and intravenous fluid requirements are decreased
postoperatively. Randomized trials have reached different conclusions about the potential advantages of retroperitoneal over
transabdominal incisions, however. Sicard et al.
prolonged ileus, small-bowel obstruction, and overall complications after transabdominal compared with retroperitoneal aortic
surgery, although pulmonary complications were similar. Cambria
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et al.
found no differences in these incisions in terms of pulmonary complications, fluid or blood requirements, or other postoperative complications, except for slightly prolonged return to oral
intake after the transperitoneal approach.
In the most recent randomized trial, Sieunarine et al.
found no differences in operating time, cross-clamp time, blood
loss, fluid requirement, analgesia requirement, gastrointestinal
function, ICU stay, or hospital stay for transperitoneal versus retroperitoneal approaches for aortic surgery. In long-term follow-up,
however, there were significantly more wound problems (hernias,
bulging, and pain) in the retroperitoneal group. These results suggest that in most cases, the choice of incision for AAA repair is
a matter of personal preference. However, both the transperitoneal and retroperitoneal approaches have advantages in certain
patients. Relative indications for retroperitoneal exposure include
a “hostile” abdomen due to multiple previous transperitoneal
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reported more
operations, an abdominal wall stoma, a horseshoe kidney, an
inflammatory aneurysm, or anticipated need for suprarenal endarterectomy or anastomosis, mindful that the retroperitoneal
approach provides facilitated access to the visceral aorta or even
supraceliac aortic segments. Relative indications for a transperitoneal approach include a ruptured AAA, coexistent intraabdominal pathology, uncertain diagnosis, left-sided vena cava, large
bilateral iliac artery aneurysms, or need for access to both renal
arteries. Advantages of each approach make it advisable for surgeons to become proficient with both techniques.
TRANSPERITONEAL APPROACH
After entering the abdomen through a transperitoneal incision,
the abdomen is thoroughly explored to exclude other pathology and assess extent of the aneurysm. The transverse colon is
then retracted superiorly, and the ligament of Treitz is divided to
allow retraction of the small bowel to the right. Exposure is greatly
assisted using a fixed self-retaining retractor. A longitudinal incision
is made in the peritoneum just to the left of the base of the smallbowel mesentery to expose the aneurysm. This incision extends
from the inferior border of the pancreas proximally to the level
of normal iliac arteries distally. Care must be taken to avoid the
ureters, especially if exposure includes the iliac bifurcation where
the ureters normally cross. Autonomic nerves to the pelvis course
anterior to the proximal segment of the left CIA and should be
retracted with associated retroperitoneal tissue rather than incised,
to prevent sexual dysfunction in men. The left renal vein should
be identified and retracted superiorly if necessary to fully expose
the neck of the aneurysm. Care must be taken not to avulse renal
vein tributaries, particularly a descending lumbar vein, frequently
encountered to the left of the aorta, which must be divided before
the left renal vein is mobile enough to allow upward retraction.
Rarely, proximal exposure cannot be obtained without division of
the left renal vein. In such cases, this should be done at its junction
with the vena cava to maintain patency of collateral drainage via
adrenal and gonadal branches. In a recent study by Sampson et al.,
56 patients underwent left renal vein division and ligation during
open aortic surgery; none developed directly related complica-
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tions.
If necessary, reanastomosis can be performed if renal vein
engorgement suggests inadequate collateral drainage.
After obtaining adequate aortoiliac exposure, the normal
aorta and iliac arteries are dissected sufficiently to place a vascular clamp proximal and distal to the aneurysm. Regardless of
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the proximal extent of an infrarenal AAA, it is desirable to construct the proximal aortic anastomosis near the renal arteries to
avoid subsequent aneurysmal degeneration of residual infrarenal
aorta. When an AAA approaches or involves the renal arteries, it
can be safer to apply the cross-clamp proximal to the celiac artery,
rather than between the renal arteries and the superior mesenteric
artery (SMA). Green et al.
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demonstrated much higher operative
mortality (32% vs. 3%) and renal failure requiring dialysis (23% vs.
3%) after infrarenal AAA repair when clamping was performed
between the SMA and renal arteries rather than proximal to the
celiac artery. They attributed this to the greater likelihood of dislodging atherosclerotic debris in the pararenal aorta as opposed to
the supraceliac aorta, which is usually less diseased. Complications
resulted from atheroembolization to the kidneys, legs, and intestine
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or injury to the aorta or renal arteries.
Others have also noted the relative safety of clamping the
supraceliac aorta, which can easily be accessed by dividing the
gastrohepatic ligament and the diaphragmatic crus.
aortic clamping between the renal arteries and the SMA is also safe
when performed in properly selected patients without extensive
plaque in this region.
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Occasionally it is possible to obtain distal
control of an AAA on the aorta, but usually aneurysmal changes or
calcification in this location make iliac artery clamping preferred.
A disease-free area of proximal aorta and iliac arteries should be
identified for clamping to minimize the possibility of clamp injury
or embolization of arterial debris. Some iliac arteries may be so
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However,
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