Routine aortography before abdominal aortic aneurysmectomy. A prospective study

Prospective Study by Ultrasonography of Abdominal Aortic Diameter in Atherosclerosis of the Lower Limbs—The Role of Atheromatous Disease

The diameter of the infrarenal abdominal aorta was measured by ultrasonography B- mode scan in 1,413 surgically intact patients with atherosclerosis of the lower limbs. There was a similar increase in abdominal aortic diameter with age in both sexes. Pathologic diameter in men patients was recorded mainly after sixty years of age: in women patients it was observed after the age of seventy. The major risk factors for aortic aneurysm in atherosclerosis obliterans of the lower limbs are smoking, hyperlipidemia with elevated levels of cholesterol, and all three factors combined in association with hypertension. Abdominal aortic diameter was only significantly affected by iliac stenosis.

Cost of routine screening for carotid and lower extremity occlusive disease in patients with abdominal aortic aneurysms

OBJECTIVE

The burden of clinically relevant noncoronary atherosclerotic occlusive disease in patients with abdominal aortic aneurysms (AAAs) is poorly defined. Furthermore, the cost-effectiveness of routine versus selective preoperative noninvasive examination of the carotid and lower extremity arterial beds has not been established in patients who undergo elective AAA repair.

METHODS

Diagnostic vascular laboratory study results were reviewed in 206 patients who underwent evaluation before AAA repair from 1994 to 1998. The patients underwent routine preoperative carotid duplex scan examinations and lower extremity Doppler scan arterial studies with ankle-brachial index (ABI) determinations. The medical records were reviewed for the identification of clinical evidence consistent with cerebrovascular or lower extremity arterial occlusive disease. The costs of routine screening and selective screening were determined with Medicare reimbursement schedules.

RESULTS

The prevalence rate of advanced (80% to 100%) carotid artery stenosis (CAS) was 3.4%, and 18% of the patients had CAS between 60% and 100%. Advanced peripheral vascular occlusive disease (PVOD; ABI, <0.3) was found in 3% of the patients, and 12% of the patients had an ABI of less than 0.6. Most patients with advanced CAS (71%) or advanced PVOD (83%) had clinical indications of their disease. The absence of clinical evidence of disease had a negative predictive value of 99% for both advanced CAS and PVOD. The cost of routine screening for all patients for advanced CAS was $5445 per case. Routine screening for severe PVOD costs were $3732 per case discovered. In contrast, the costs for selective screening for advanced CAS or PVOD in patients with appropriate history or symptoms were $1258 and $785 per case found, respectively.

CONCLUSION

Routine noninvasive diagnostic testing for the identification of asymptomatic CAS and PVOD in patients with AAA may not be justified. Preoperative screening is more clearly indicated for patients with AAAs who have clinical evidence suggestive of CAS or PVOD.

Iliac arterial injuries after endovascular repair of abdominal aortic aneurysms: correlation with iliac curvature and diameter

PURPOSE

To determine the relationship between iliac arterial tortuosity and cross-sectional area and the occurrence of iliac arterial injuries following transfemoral delivery of endovascular prostheses for repair of abdominal aortic aneurysms.

MATERIALS AND METHODS

Iliac arterial curvature values and orthogonal cross-sectional areas were determined from helical computed tomographic (CT) data acquired in 42 patients prior to transfemoral delivery of aortic stent-grafts. The curvature and luminal cross-sectional area orthogonal to the median centerline were quantified every millimeter along the median centerline of the iliac arteries. An indicator of global iliac tortuosity, the iliac tortuosity index, was defined as the sum of the curvature values for all points with a curvature of 0.3 cm(-1) or greater, and cross-sectional area (CSA) was indexed for all points as the mean cross-sectional diameter (D = 2 radical[CSA/pi]). Following stent-graft deployment, helical CT data were analyzed for the presence of iliac arterial dissections independently by two reviewers.

RESULTS

Eighteen dissections were detected in 16 patients. The iliac tortuosity index was significantly larger in iliac arteries with dissections (35.5 +/- 20.8 [mean +/- SD]) when compared with both nondissected contralateral iliac arteries in the same patients (26.1 +/- 21.0, P =.001) and iliac arteries in patients without any iliac arterial injury (20 +/- 9, P =.009). The tortuosity index was higher ipsilateral to the primary component delivery in 10 of 11 iliac dissections that developed along the primary component delivery route.

CONCLUSION

A high degree of iliac arterial tortuosity appears to impart greater risk for the development of iliac arterial injuries in patients undergoing transfemoral delivery of endovascular devices.

Mesenteric revascularization during aneurysmectomy

The most important association between aortic aneurysm surgery and the mesenteric circulation is the potential for inadvertent compromise to the mesenteric trunks and their end organs. Preservation of visceral blood flow is a critical objective in each case, using methods that have been developed as techniques for suprarenal abdominal and thoracoabdominal aneurysmectomy have evolved. Beyond simply preserving what existed, revascularization by endarterectomy or bypass has a role in selected cases to improve the natural history of advanced mesenteric occlusive disease, although the rationale for such prophylactic surgery must remain relatively weak until more is learned about disease progression in the visceral arteries. Finally, a small number of patients with mesenteric ischemic symptoms at the time of aneurysmectomy clearly benefit from combined surgery.

Clinical analysis of abdominal aortic aneurysms associated with iliofemoral occlusive disease

Patients with abdominal aortic aneurysm (AAA) associated with iliofemoral occlusive disease due to arteriosclerosis obliterans (ASO) are often encountered clinically, but their clinical characteristics remain poorly defined. We divided 275 patients undergoing aneurysmectomy into 2 groups: 58 patients with both AAA and ASO (Group A) and 217 patients with AAA only (Group B). General characteristics, morphological features of the aneurysms, surgical procedures and operative results were then compared between the groups. In Group A, ruptured aneurysms were significantly less common (p = 0.005) and the aneurysms were smaller (p = 0.0009). The most common cause of death in Group A was acute myocardial infarction (3/7), in contrast to aneurysmal rupture of another arterial segment and malignancy (6/27, each) in Group B. These findings indicate that patients with AAA and ASO represent a subgroup of patients with particular clinical features.

Magnetic resonance angiography in the preoperative evaluation of abdominal aortic aneurysms

PURPOSE

Contrast arteriography (CA) is a useful but invasive technique for the preoperative evaluation of patients with abdominal aortic aneurysms (AAA). To evaluate the use of magnetic resonance arteriography (MRA) as a preoperative study we prospectively studied 38 patients undergoing AAA repair.

METHODS

All patients underwent biplane CA and MRA with use of a gadolinium-enhanced technique. Radiographic studies were then independently evaluated by blinded radiologists for anatomic findings with CA used as the standard. Studies were then independently evaluated by blinded vascular surgeons, and a surgical plan was made.

RESULTS

With CA and intraoperative findings as the standards, MRA proved highly accurate in the determination of multiple key anatomic elements. The proximal extent of aneurysmal disease was correctly predicted in 87% (33/38) patients. Significant iliofemoral occlusive disease was identified with a sensitivity of 83% (5/6). Iliac or femoral aneurysms were detected with a sensitivity of 79% (22/28) and specificity of 86% (41/48). Significant renal artery stenosis was detected with a sensitivity of 71% (12/17) and a specificity of 99% (72/73). Accessory renal arteries were correctly identified in 71% (12/17). Surgeon evaluators correctly predicted the proximal cross-clamp site in 87% (33/38) of patients with use of MRA as compared with the actual operative conduct. Proximal anastomotic sites were correctly predicted in 95% (36/38) with MRA and 97% (37/38) with CA. Renal revascularization was predicted by MRA with a sensitivity of 91% (10/11) and specificity of 100% (65/65). The use of bifurcated aortic prostheses was correctly predicted by MRA in 75% (12/16), which was similar to that predicted by CA (81%, 13/16).

CONCLUSIONS

MRA can provide preoperative anatomic information that is equivalent to CA for surgical planning. Because of favorable cost and patient safety considerations MRA will assume increasing importance in the preoperative evaluation of AAA.

Preoperative assessment of abdominal aortic aneurysm: the value of helical and three-dimensional computed tomography

PURPOSE

The purpose of this study was to evaluate the utility of helical computed tomography (CT) in the preoperative assessment of abdominal aortic aneurysms (AAA) and to compare its accuracy with aortography and operative findings.

METHODS

Thirty-two patients with suspected AAA were evaluated by helical CT with either 5 mm collimation (slice thickness) or a combination of 3 mm collimation through the renal and mesenteric arteries and 7 mm collimation through the remainder of the AAA. Three-dimensional reconstructions were performed with use of three different techniques, and results were compared with aortography and surgery.

RESULTS

Twenty-five patients were found to have an aneurysm, and 19 subsequently underwent surgery. Standard angiography was also performed in 13. The location, size, and extent of the aneurysm, as well as the wall calcification and intraaneurysmal thrombus, were well depicted with helical CT. The visceral aortic branches, including the detection of renal artery stenosis and accessory renal arteries, were consistently seen with the 3 mm/7 mm collimation protocol and three-dimensional reconstruction.

CONCLUSION

Helical CT with three-dimensional display of the aorta and its branches combines the advantages of conventional CT imaging and aortography. This technique appears to provide comprehensive preoperative evaluation of AAA.

Detection of unsuspected renal artery stenoses in patients with abdominal aortic aneurysms: refined indications for preoperative aortography

Renal artery stenoses (RASs) that are unsuspected on clinical grounds are common in patients with peripheral vascular disease. These lesions may be missed in patients with abdominal aortic aneurysms (AAAs) who undergo arteriography based on selective clinical indications alone. We reviewed 98 consecutive patients with AAAs to determine how often selective arteriography would fail to diagnose unsuspected RAS. The location and degree of RASs were noted on preoperative arteriograms, which were routinely obtained in all patients considered for AAA repair during the study period. Medical records were studied to determine the presence of selective clinical indications for preoperative arteriography (moderate to severe hypertension or renal insufficiency). Twenty-four patients had a significant (> or = 50% diameter loss) RAS, and 10 patients had a severe (> or = 75% diameter loss) RAS or renal artery occlusion. Patients with significant RAS had a higher incidence of hypertension (p = 0.035) and renal insufficiency (p = 0.018). All 10 patients with severe RASs required at least two antihypertensive medications to control their hypertension compared with 22 of 88 patients who did not have a severe RAS (p < 0.001). Forty-three patients had an indication for arteriography according to selection criteria (renal insufficiency, moderate or severe hypertension, or both). No severe RASs were found in patients who did not meet the selection criteria for arteriography. Using arteriography based on the presence of hypertension requiring two or more medications for control will detect the vast majority of severe, unsuspected RASs in AAA patients.

Selective use of arteriography in the assessment of aortic aneurysm repair

Routine preoperative arteriography is advocated by many vascular surgeons before abdominal aortic aneurysm repair. We have used a selective approach based on the facts that arteriography is expensive, time-consuming, potentially hazardous, and often unwarranted. Based on preoperative indications, arteriography was used selectively in 41 of 100 consecutive patients prior to abdominal aortic aneurysmectomy. Many patients had more than one indication. A total of 82 specific indications were recognized. The most frequent indications were diminished lower extremity pulses (24), claudication (20), severe coronary artery disease (11), cerebrovascular disease (7), prior arterial reconstruction (8), hypertension in patients 60 years of age or less (5), evidence of other aneurysms (4), major renal anomaly (1), blue toe syndrome (1), and thoracic aneurysm (1). The 41 arteriograms produced 125 specific arteriographic abnormalities with an average of three per study. The most arteriographic abnormalities were in those patients with claudication and the least for those with hypertension. The arteriogram revealed information that would not have been obvious at operation, nor would it have led to operative procedure modification in only 10 patients. In the 59 patients not having arteriography, three had intraoperative findings which demanded a modification of the operative procedure. Thus, in only 13 patients was arteriography definitely useful. Presumably it was not indicated in the other 87. By comparing the cases in which the operation was modified with the presence of a specific indication, we have developed a predictability index as a guide for performing arteriography. Multiple indications increased the likelihood of operation modification only if four or more indications were present.

Preoperative imaging of aortic aneurysms. Conventional and digital subtraction angiography, computed tomography scanning, and magnetic resonance imaging

Aneurysm imaging is important in deciding on the timing of and operative approach for aneurysmorrhaphy. Various noninvasive and invasive imaging techniques are available for the anatomic definition of abdominal aortic aneurysms, involvement of adjacent structures, and intra-abdominal pathology. Careful preoperative evaluation can avert hemorrhagic, embolic, and ischemic complications of elective aneurysm repair.

Repair of abdominal aortic aneurysms in patients with renal, iliac, or distal arterial occlusive disease

Appropriate preoperative vascular assessment of patients presenting with aortic aneurysms and arterial occlusive disease is essential to obtain the optimal results from aneurysm repair. The renal arteries should be evaluated in patients with hypertension or renal dysfunction, and stenosis must be addressed when seen on arteriograms. Hemodynamically significant lesions are candidates for bypass concomitant with aortic replacement. The stump pressure of a patent inferior mesenteric artery should be assessed intraoperatively, and bypass or reimplantation should be performed if colon ischemia might result from internal mesenteric artery ligation. If vasculogenic impotence is suggested by preoperative studies, meticulous nerve-sparing dissection and revascularization of the internal iliac arteries may result in recovery of erectile function in some patients. In all cases of aneurysm repair, the hypogastric circulation must be maintained through either direct revascularization or bypass to major collateral arteries. Iliac occlusive disease may be evaluated with several modalities, including physical examination, noninvasive laboratory testing, arteriography, and the papaverine test, to determine whether critical or subcritical stenoses are present. Aortic bifurcation grafts should be used to construct the distal anastomoses beyond areas of significant disease. The extent of lower-extremity occlusive disease directly affects the long-term patency of aortic replacement, and diligent follow-up is necessary for timely intervention to maintain patency of vascular reconstructions.

Comparison of NMR imaging and aortography for preoperative evaluation of abdominal aortic aneurysm

Seven patients (five male and two female, age range from 50 to 88) with angiographic proven abdominal aortic aneurysms were evaluated with magnetic resonance (MR) imaging (1.5-kG system) of the abdomen. Images were obtained in transverse, coronal, and saggital planes with three radiofrequency pulse sequences [saturation recovery (SR), inversion recovery (IR), and spin echo (SE)]. All of the aneurysms were identified as to site and relative size with MR images. The lumen in which there was rapidly flowing blood was always dark (low intensity), whereas the aneurysmal area which contained presumed clot or slow flowing blood was brighter (high intensity) on SR images. Although the size, location, and relationship to other blood vessels was best demonstrated on aortography, MR images provided similar information in all cases. MR images correctly demonstrated thrombus in six cases. In conclusion, MR imaging provides a clear delineation of the anatomy of abdominal aortic aneurysms. In addition, it can provide information concerning tissue type, i.e., it distinguished clot from moving blood. It may be possible in the future to further characterize atherosclerotic and other pathological changes in vessel architecture by using various pulse sequences and timing parameters to provide in vivo histological typing.

The utility of digital subtraction arteriography in peripheral vascular disease

Digital subtraction angiography (DSA), whether used in conjunction with intravenous or intraarterial injection techniques, has an established role in evaluation of peripheral vascular disease. Use of DSA can reduce the time, cost, and patient discomfort of the standard arteriographic study. While it is limited by field size and patient cooperation in some instances, the utility of noninvasive imaging using intravenous DSA and the added anatomic detail of intraarterial DSA for roadmapping and delineation of small distal vessels provide the basis for future integration of standard arteriographic and DSA methods in assessment of peripheral vascular disease.