Faculty Bibliography

OBJECTIVES: We noted substantial differences when measuring repeatedly the same abdominal aortic aneurysm (AAA) on the same computed tomography (CT) scan. This study quantitated this variability, and methods to minimize it were developed. METHODS: The CT maximal diameter of 25 AAAs was measured by eight experienced observers, including six vascular surgeons and two radiologists, using two methods: an unstandardized protocol, and a standardized protocol using fine calipers to carefully measure the largest diameter perpendicular to the estimated aneurysm centerline, from outer aneurysm wall to outer wall. The average measurement difference between observers was calculated for each method. The average difference between each observer's measurement and the official radiology report value was also calculated. Agreement between the two measurement methods was assessed with Bland-Altman plots. RESULTS: The difference in maximal diameter measurements between each observer averaged 4.0 +/- 5.1 mm (range, 0.0-35.0 mm) with the unstandardized method. The mean measurement difference with the standardized protocol was significantly lower, and averaged 2.8 +/- 4.4 mm (range, 0.0-26.0 mm; P <.05). Measurements taken from the official radiology report differed from each of the observer's standardized measurement by an average of 5.0 +/- 6.3 mm (range, 0.0-28.0 mm). This difference was similar for both the unstandardized and standardized methods. Bland-Altman plots confirmed the wide variation of the maximal diameter measurements when the unstandardized method was compared with the standardized method (95% confidence interval, -9-9 mm). CONCLUSIONS: Routine CT maximal diameter measurement of AAAs can have substantial interobserver variability. Standardized measurement protocols can decrease, but not eliminate, this measurement variability. Thus apparent size changes based on CT measurements may represent measurement artifact rather than actual aneurysm growth or shrinkage, particularly when a standardized system is not used

PURPOSE: It is widely believed that chronic renal insufficiency (CRI) greatly increases the risk associated with endovascular abdominal aortic aneurysm repair (EVAR) and is a relative contraindication to the procedure and to the use of intra-arterial contrast agents (IACA). We reviewed a 5-year EVAR experience to determine whether the procedure and use of IACA have an important deleterious effect on renal function in patients with and without pre-existing CRI. METHODS: Endovascular aneurysm repair (EVAR) was performed in 200 patients with a variety of endografts, with intra-arterial contrast agents. The patients were retrospectively assigned to three groups on the basis of preoperative serum creatinine concentration (Cr): group 1 (n = 108), Cr less than 1.5 mg/dL (normal range); group 2 (n = 65), Cr 1.5 to 2.0 mg/dL; group 3 (n = 27), Cr 2.1 to 3.5 mg/dL. No patients had undergone hemodialysis. In groups 2 and 3, patients received hydration perioperatively, and received mannitol intraoperatively; no nephrotoxic drugs were administered during the procedure, other than nonionic contrast agent (Omnipaque 350). RESULTS: The incidence of postoperative complications between the three study groups was not statistically different. In group 1 a transient increase in serum Cr (>30% over baseline and >1.4 mg/dL) was noted in three patients (2.7%), two of whom (1.9%) required temporary hemodialysis and one (0.9%) who died of renal failure. In group 2 a transient increase in serum Cr was noted in two patients (3.1%); both patients (3.1%) required temporary hemodialysis, and one patient (1.5%) died of renal failure. In group 3 a transient increase in serum Cr was noted in two patients (7.4%); one patient (3.7%) required temporary hemodialysis, and one patient (3.7%) died of renal failure. Perioperative hypotension significantly increased the risk for elevated serum Cr and death (P <.05), and larger contrast volume was associated with an increase in serum Cr (P <.05) during the postoperative period. CONCLUSIONS: EVAR with intra-arterial contrast agents can be accomplished in patients with chronic renal insufficiency who do not require dialysis, with limited and acceptable morbidity and mortality, similar to that observed with open aneurysm repair. Contrary to other reports in which perioperative precautions were not used, our study shows that with EVAR the risk for worsening renal failure, dialysis, and death is only slightly, and not significantly, greater in patients with preoperative chronic renal insufficiency compared with patients with normal renal function. Perioperative hypotension and increased contrast volume are significant risk factors for postoperative increase in serum Cr and death. With appropriate precautions such as averting perioperative hypotension and limiting the volume of nonionic contrast agents, elevated Cr need not be a contraindication to EVAR with intra-arterial contrast agents

OBJECTIVE: Persistent aneurysm perfusion or endoleak is associated with pulsatility of abdominal aortic aneurysm (AAA) after endovascular repair. However, the resultant pulsatile change in aneurysm diameter may be difficult to quantify, and therefore its significance is unknown. In this study cine magnetic resonance angiography (MRA) was used to quantify aneurysm wall motion during the cardiac cycle and to correlate it with the presence and type of endoleak. METHODS: Cine MRA was performed in 16 patients undergoing endovascular repair of AAA. A 1.5 T magnet and post-processing with GEMS 4.0 Fiesta computerized video image analysis software were used to calculate maximum aortic diameter during systole and diastole. Changes in aortic diameter were determined from these measurements. Cine MRA was performed on aneurysms before treatment and in patients with and without endoleak after endovascular repair. Type of endoleak was confirmed at angiography in all cases. Four patients had antegrade (type I) endoleak, and eight patients had retrograde (type II) endoleak; no endoleak was present in four patients. Endovascular grafts with stent support throughout the entire length of the graft (Talent) were used in all cases (14 bifurcated grafts, 2 tube grafts). RESULTS: Cine MRA demonstrated significantly greater wall motion and resultant change in aneurysm diameter in patients with type I endoleak compared with patients without endoleak (type I, 2.14 +/- 1.28 mm vs no endoleak, 0.12 +/- 0.09 mm, P =.001). Change in aneurysm diameter in patients with type II endoleak was not significantly greater than in patients with no endoleak (type II, 0.26 +/- 0.21 mm vs no endoleak, 0.12 +/- 0.09 mm, P = NS). Untreated aneurysms demonstrated the greatest change in diameter during the cardiac cycle (3.51 +/- 0.79 mm). CONCLUSION: Cine MRA may be used to accurately quantify AAA wall motion before and after endovascular stent-graft treatment. The extent of change in diameter corresponds to the type of endoleak, with antegrade (type I) endoleak generating greater pulsatile change in diameter than retrograde-collateral (type II) endoleak or no endoleak. Cine MRA may provide a noninvasive means of assessing the success of endovascular treatment of AAA. Further studies will be necessary to confirm the utility and efficacy of cine MRA in postoperative assessment of endovascular aneurysm repair

OBJECTIVES: Transrenal fixation (TFX) of aortic endografts is thought to increase the risk for renal infarction and impaired renal function. We studied the late effects of TFX on renal function and perfusion. METHODS: Of 189 patients with commercial aortic endografts, which we inserted between 1995 and 2002, we reviewed data for 130 patients (112 men, 18 women) with available creatinine (Cr) concentration and contrast enhanced computed tomography (CT) scans preoperatively and 1 to 97 months after the procedure. Of the 130 patients, 69 patients had TFX and 61 patients had infrarenal fixation (IFX). Both groups were physiologically comparable. Average age was 76 +/- 8 years for patients with TFX and 75 +/- 8 years for patients with IFX. Presence of renal infarct or renal artery occlusion was determined by nephrograms on serial contrast-enhanced CT scans. RESULTS: Mean follow-up was 17 +/- 16 months (range, 1-54 months) for TFX and 21 +/- 21 months (range, 1-97 months) for IFX. Mean serum Cr concentration increased significantly during long-term follow-up in both groups (TFX, 1.3 +/- 0.5 mg/dL to 1.5 +/- 0.8 mg/dL, P <.01; IFX, 1.3 +/- 0.7 mg/dL to 1.4 +/- 0.8 mg/dL, P <.03). Creatinine clearance (CrCl) similarly decreased over long-term follow-up in both groups (TFX, 53.3 +/- 17.7 mL/min/1.73 m(2) to 47.9 +/- 16.2 mL/min/1.73 m(2), P <.01; IFX, 58.1 +/- 22.7 mL/min/1.73 m(2) to 53.1 +/- 23.4 mL/min/1.73 m(2), P <.02). There were no significant differences in the increase in Cr concentration (P =.19) or decrease in CrCl (P =.68) between TFX and IFX groups. Small renal infarcts were noted in four patients (5.8%) in the TFX group and one patient (1.6%) in the IFX group. No increase in Cr concentration or decrease in CrCl was noted in any patient with a renal infarct. Postoperative renal dysfunction developed in 7 of 69 patients (10.1%) in the TFX group and 7 of 61 patients (11.5%) in the IFX group. There were no statistically significant differences between groups with respect to number of patients with new renal infarcts (P =.37) or postoperative renal dysfunction (P =.81). CONCLUSION: There is a slight increase in serum Cr concentration and decrease in CrCl after aortic endografting. However, there was no significant difference in these changes between patients with TFX and IFX. Although TFX may produce a higher incidence of small renal infarcts, these do not impair renal function. Thus our midterm results suggest that TFX can be performed safely, with no greater change in renal function than observed after IFX

OBJECTIVE: The lack of aneurysm pulsatility after endovascular aneurysm repair (EVAR) is deemed by some an important guide to the effectiveness of exclusion. However, factors that contribute to aneurysm pulsatility after EVAR have not been elucidated. This study quantitatively analyzed the effects of systemic pressure, aneurysm sac pressure, endoleak, branch outflow from aneurysm sac, and intra-sac thrombus on aneurysm pulsatility after EVAR. METHODS: In an ex vivo model, an artificial aneurysm sac was incorporated within a mock circulation comprised of rubber tubing and a pulsatile pump. The aneurysm sac was then completely excluded from the circulatory circuit with two types of stent-grafts, ie, supported and unsupported, and heparinized canine blood was circulated. Systemic circulation and aneurysm sac pressure was recorded in the absence and presence of endoleaks, and simulated open and closed lumbar branch outflow from the aneurysm sac. The aneurysm sac was then filled with organized human thrombus, and all pressure measurements were repeated. Two observers blinded to the above-mentioned variables independently evaluated aneurysm sac pulsatility with palpation in five separate experiments. Analysis of variance was performed, with significance accepted at P =.05. RESULTS: Systemic pressure was simulated in the artificial circulation to range from 100/60 to 180/60 mm Hg. Regardless of the simulated lumbar branch outflow from the aneurysm, sac pressure was directly related to the presence of endoleak (P <.001). Aneurysm sac pulsatility was present only when the lumbar branch outflow was patent and not dependent on sac pressures. Aneurysm sac thrombosis or type of stent-graft did not influence sac pressure and pulsatility. CONCLUSIONS: In this model, after EVAR pulsatility depends on aneurysm sac outflow, regardless of endoleak, sac thrombosis, sac pressure, or stent-graft. Furthermore, persistent pulsatility does not predict systemic intra-sac pressure, nor does lack of pulsatility reflect freedom of the aneurysm sac from systemic pressurization. This ex vivo model suggests that aneurysm pulsatility is an unreliable guide for predicting aneurysm sac pressurization after EVAR. Other diagnostic methods must be used to assess successful aneurysm exclusion

OBJECTIVE: Subintimal angioplasty (SIA) has been advocated to treat long segment lower extremity arterial occlusions, but many question its value. We evaluated the role of SIA in a group of patients with severe lower extremity arterial occlusive disease. METHODS: During a 2.5-year period, 39 patients with arterial occlusions (median length, 8 cm; range, 2 to 31 cm) were treated on an intention-to-treat basis with SIA. Twenty-five patients had gangrene, five had rest pain, and nine had disabling (<one block) claudication. There were 24 superficial femoral, two superficial-femoral-popliteal, four popliteal, two popliteal-tibial, five tibial, and two external iliac artery lesions. With fluoroscopic guidance, via a prograde common femoral artery puncture (n = 29) or a contralateral common femoral artery puncture (n = 9), a subintimal dissection plane was created across the occlusion with a standard guidewire and catheter. The arterial lumen was reentered distal to the occlusion, and the recanalized segment balloon was dilated. All patients were followed prospectively with arterial duplex scan. RESULTS: SIA was technically successful in 34 of 39 patients (87%). All five failures were from an inability to reenter the patent lumen distally. These five patients underwent successful bypasses that in no case were more distal than would have been required before SIA. In the 34 technically successful SIAs, pain completely resolved (14/14) and areas of gangrene (21/25) healed. The cumulative patency rate in patients who underwent successful SIA was 74% +/- 10% at 12 months. The mean increase in ankle-brachial index after SIA was 0.34 (range, 0.1 to 0.69). There were two distal embolic events, successfully treated surgically (n = 1) or with catheter-directed techniques (n = 1). Three patients underwent subsequent bypass, and the remaining five patients remain asymptomatic. CONCLUSION: SIA is feasible and can be effective in some patients with lower extremity arterial occlusions and threatened limbs. These results, plus SIA's many advantages, support an increasing role for it in the treatment of lower extremity arterial occlusive disease

OBJECTIVE: Patients with infrainguinal occlusive disease may experience spontaneous symptomatic improvement. This is generally thought to be from augmented collateral circulation. This study reports another mechanism. METHODS: Over a 20-year period, 4123 patients underwent lower extremity arteriography for limb ischemia. For a variety of reasons, 451 patients had repeat arteriography. RESULTS: Five patients were identified as having conclusive arteriographic evidence of spontaneous recanalization of occluded arterial segments without having undergone any surgical or thrombolytic interventions. Repeat contrast arteriography was performed on these patients for failing grafts (n = 2) or contralateral lower extremity ischemia (n = 3). Three other patients had magnetic resonance arteriographic or duplex arteriographic evidence of spontaneous arterial recanalization. Spontaneous recanalizaton occurred in ileofemoral (n = 2), superficial femoral (n = 2), popliteal (n = 3), and peroneal (n = 1) arterial segments. The average time interval of occlusion to recanalization was 21 weeks (2 weeks to 2 years). Two of the eight patients had failed revascularization procedures before spontaneous recanalization. All eight patients had restoration of pulses distal to the recanalized segments and significant symptomatic improvement as defined with the Society for Vascular Surgery/American Association for Vascular Surgery categories for limb ischemia. CONCLUSION: Spontaneous recanalization of arterial segments can occur and must be considered when evaluating other proposed treatments of critical limb ischemia, including cilostazol, lytic agents, and angiogenic agents, such as vascular endothelial growth factor. Although its true incidence is unknown, this represents another mechanism for spontaneous symptomatic improvement without treatment in patients with severe limb ischemia

OBJECTIVE: An accepted fact is that abdominal aortic aneurysms (AAAs) larger than 5.5 cm should undergo elective repair. However, subsets of these patients have serious comorbid conditions, which greatly increase operative risk. This study evaluated the outcomes of periods of protracted nonoperative observational management with selective delayed surgery in patients at high risk with large infrarenal and pararenal AAAs. METHODS: Among 226 patients with AAAs more than 5.5 cm, we selected 72 with AAAs from 5.6 to 12.0 cm (mean, 7.0 cm) for periods of nonoperative management because of their prohibitive surgical risks. Comorbid factors included a low ejection fraction of 15% to 34% (mean, 22%) in 18 patients, 1 second forced expiratory volume less than 50% (mean, 38%) in 25, prior laparotomy in 10, and morbid obesity in 22. Follow-up examination was complete in the 72 patients for the 6 to 76 months (mean, 23 months) that they underwent nonoperative treatment. Fifty-three patients ultimately underwent operation because of AAA enlargement or onset of symptoms after 6 to 72 months (mean, 19 months) of nonoperative treatment. RESULTS: Of the 72 selected patients, 54 (75%) are living and 18 (25%) are dead. Seven patients who underwent only nonoperative treatment presently survive after 28 to 76 months (mean, 48 months). Of the 18 deaths, AAA rupture occurred in only three patients (4%) who were observed for 12, 31, and 72 months before rupture. Nine other deaths (13%) occurred after 6 to 72 months from comorbidities unrelated to the AAA. Six of the 53 patients who underwent delayed operation died within 30 days of operation (11% mortality rate). The mortality rate for the 154 good-risk patients with an AAA who underwent prompt open or endovascular repair was 2.2%. CONCLUSION: These data indicate that some patients with large AAAs and serious comorbidities are acceptably managed for long periods (6 to 76 months) with nonoperative means. Substantial delays of 12 to 76 months resulted in an AAA rupture rate of only 4%, and 13% of these patients (nine of 72) died of comorbidities unrelated to AAA rupture or surgery. Mortality rate in this group of patients, when operated, was 11% (six of 53). These findings support the selective use of nonoperative management in some patients with large AAAs and serious comorbidities

OBJECTIVE: To analyze the late complications after endovascular graft repair of elective abdominal aortic aneurysms (AAAs) at the authors' institution since November 1992. SUMMARY BACKGROUND DATA: Recently, the use of endovascular grafts for the treatment of AAAs has increased dramatically. However, there is little midterm or long-term proof of their efficacy. METHODS: During the past 9 years, 239 endovascular graft repairs were performed for nonruptured AAAs, many (86%) in high-risk patients or in those with complex anatomy. The grafts used were Montefiore (n = 97), Ancure/EVT (n = 14), Vanguard (n = 16), Talent (n = 47), Excluder (n = 20), AneuRx (n = 29), and Zenith (n = 16). All but the AneuRx and Ancure repairs were performed as part of a U.S. phase 1 or phase 2 clinical trial under a Food and Drug Administration investigational device exemption. Procedural outcomes and follow-up results were prospectively recorded. RESULTS: The major complication and death rates within 30 days of endovascular graft repair were 17.6% and 8.5%, respectively. The technical success rate with complete AAA exclusion was 88.7%. During follow-up to 75 months (mean +/- standard deviation, 15.7 +/- 6.3 months), 53 patients (22%) died of unrelated causes. Two AAAs treated with endovascular grafts ruptured and were surgically repaired, with one death. Other late complications included type 1 endoleak (n = 7), aortoduodenal fistula (n = 2), graft thrombosis/stenosis (n = 7), limb separation or fabric tear with a subsequent type 3 endoleak (n = 1), and a persistent type 2 endoleak (n = 13). Secondary intervention or surgery was required in 23 patients (10%). These included deployment of a second graft (n = 4), open AAA repair (n = 5), coil embolization (n = 6), extraanatomic bypass (n = 4), and stent placement (n = 3). CONCLUSION: With longer follow-up, complications occurred with increasing frequency. Although most could be managed with some form of endovascular reintervention, some complications resulted in a high death rate. Although endovascular graft repair is less invasive and sometimes effective in the long term, it is often not a definitive procedure. These findings mandate long-term surveillance and prospective studies to prove the effectiveness of endovascular graft repair