National Trends and Outcomes of Pedal Bypass Surgery.

OBJECTIVE: The technical demands associated with pedal bypass (PB) surgery place it at risk of underutilization and may be limiting its widespread adoption as a valuable revascularization modality. This study aims to evaluate trends in PB performance, assess its outcomes, and compare its results between high- and low-volume centers. METHODS: All patients receiving a PB between 2003 and 2023 were identified in the Vascular Quality Initiative (VQI) infrainguinal bypass (IIB) module. The ratio of PB to total IIB performed was calculated for each year and trended over the study period. Centers performing PB were categorized according to their annual PB volume into tertiles of low-volume centers (LVC, <2 PB/year), medium-volume centers (MVC, 2-4 PB/year), and high-volume centers (HVC, >4 PB/year) for comparison. Patient characteristics and outcomes were compared using the χ2 or Fisher exact test as appropriate for categorical variables and the analysis of variance test or Kruskal-Wallis test as appropriate for continuous variables. Cox regression analysis was used to study the association between center volume and the primary outcomes of primary patency, primary-assisted patency, secondary patency, reintervention, amputation, and major adverse limb events (MALE), defined as the composite outcome of amputation and/or reintervention. RESULTS: A total of 3466 patients received a PB during the study period. The ratio of PB to IIB dropped from 14% to 4% between 2003 and 2023. Primary, primary-assisted, and secondary patency rates were 65%, 76%, and 80%, respectively, and limb salvage rate was 83% at 1 year. Nineteen percent of centers performing IIBs in the VQI did not perform any PBs during the study period. Of the 246 centers performing PBs, 78% were LVC, 15% were MVC, and only 7% were HVC. On Cox regression analysis, HVCs were associated with a lower risk of primary patency loss (hazard ratio [HR], 0.79; 95% confidence interval [CI], 0.66-0.95; P = .010), reintervention (HR, 0.75; 95% CI, 0.60-0.95; P = .016), amputation (HR, 0.77; 95% CI, 0.61-0.98; P = .034), and MALE (HR, 0.78; 95% CI, 0.66-0.93; P = .005) compared with LVCs. No difference in secondary patency between high- and low-volume centers was observed (P = .680). CONCLUSIONS: The utilization of PB operations experienced a four-fold decrease over the past 20 years, despite favorable patency and limb salvage outcomes. Centers with a higher operative volume in PB achieve better outcomes than LVCs, and accordingly, patients with extensive tibioperoneal disease may benefit from evaluation at centers with documented expertise in PB before resorting to an alternative revascularization modality or a major limb amputation.

Predictors of diffuse renal microembolization following endovascular repair of abdominal aortic aneurysms.

We evaluated the incidence, risk factors, and clinical consequences of renal microembolic events following endovascular aneurysm repair using suprarenal or infrarenal fixation. Pre- and postoperative (1 month) computed tomographic angiograms were reviewed for new renal perfusion defects. Suprarenal aortic and infrarenal neck thrombus load was classified by circumference involved and thrombus thickness. Serum creatinine was measured preoperatively, on the first postoperative day, and 1 month postoperatively. Among 136 patients, 8 (5.9%) had bilateral microembolic cortical defects. Patients with moderate or severe suprarenal thrombus were more likely to have renal microemboli than those with no or mild suprarenal thrombus (17% vs 0%; p < .001). Similarly, patients with moderate or severe infrarenal neck thrombus were more likely to have renal microemboli than those with no or mild infrarenal thrombus (9.6% vs 1.5%; p = .08). Severe infrarenal thrombus was independently predictive of microembolization (odds ratio 15.0; 95% confidence interval 1.6-142; p = .018). There was no statistically significant difference in the incidence of renal microembolization when comparing suprarenal and infrarenal fixation (8.2% vs 4.0%; p = .47). Changes in creatinine from baseline were not different in those with or without renal microemboli. Renal microembolization is an uncommon but distinct radiographic finding that is more associated with significant neck thrombus than fixation level.

Endovascular management of isolated iliac artery aneurysms.

OBJECTIVE: We reviewed our experience with endovascular treatment of isolated iliac artery aneurysms (IAAs). METHODS: Medical records for consecutive patients undergoing endovascular IAA repair from 1995 to 2004 were reviewed. Computed tomography (CT) angiograms were used to assess IAA location, size, and presence of endoleaks after endovascular repair. Rates of primary patency and freedom from secondary interventions were estimated using the Kaplan-Meier life-table method. RESULTS: From July 1995 to November 2004, 45 patients (42 men), with a mean age of 75 years, underwent endovascular repair of 61 isolated IAAs: 41 common iliac, 19 internal iliac, and one external iliac. Five patients (11%) were symptomatic, although none presented with acute rupture. The mean preoperative IAA diameter was 4.2 +/- 1.7 cm. Fifteen patients (33%) had prior open abdominal aortic aneurysm repair. Local or regional anesthesia was used in 28 cases (62%). Thirty-four patients (75%) were treated with unilateral iliac stent-grafts, eight (18%) with bifurcated aortic stent-grafts, and three (7%) with coil embolization alone. Perioperative major complications included one early graft thrombosis that eventually required conversion to open repair and one groin hematoma that required operative evacuation. On follow-up, late complications included one additional graft thrombosis and one late death after amputation. No late ruptures occurred after endovascular repair, with a mean follow-up of 22 months (range, 0 to 60 months). The mean postoperative length of stay was 1.3 +/- 1.0 days. On postoperative CT scans obtained at 1, 6, 12, 24, and 36 months, aneurysm shrinkage was noted in 18%, 29%, 57%, 67%, and 83% of IAAs, respectively, compared with the baseline diameter. One hypogastric aneurysm enlarged in the presence of a later identified type II endoleak. Five endoleaks were noted (4 type II, 1 indeterminate) at 1 month, with four other endoleaks (1 type II, 1 type III, 2 indeterminate) identified on later CT scans. At 2 years, primary patency was 95%, and freedom from secondary interventions was 88%. CONCLUSIONS: Endovascular repair of isolated IAAs appears safe and effective, with initial results similar to those after endovascular abdominal aortic aneurysm repair.

Can computed tomography scan findings predict "impending'' aneurysm rupture?

Several findings on computed tomography (CT) scans of intact aneurysms have been taken to suggest "imminent'' or "impending'' aneurysm rupture. Often these are identified incidentally in asymptomatic patients when an urgent operation was not planned and may even be ill advised. The authors evaluated whether these signs can truly predict short-term aneurysm rupture. A computerized medical archival system was reviewed from August 1994 to August 2004. Patients with aortic aneurysms and official CT scan reports of "impending rupture'' were reviewed. CT films and reports were reviewed for aneurysm characteristics, while computerized medical records were reviewed for patient demographics, comorbidities, symptoms, documented subsequent rupture, and operative findings. Signs of "impending rupture'' included the crescent sign, discontinuous circumaortic calcification, aortic bulges or blebs, aortic draping, and aortic wall irregularity. Rupture occurring within 2 weeks of the index CT was defined as supporting the "imminent'' label. Forty-five patients with aortic aneurysms and CT stigmata of "impending rupture'' were identified. Five patients with additional signs of suspicious leak and 1 with an infected previously repaired aneurysm were excluded. Of 39 intact aneurysms, 26 (67%) were infrarenal, 2 (5%) were suprarenal, and the remaining 11 (28%) were thoracoabdominal. The patient group had more women than expected (19/39, 49%) and larger aneurysms (mean diameter, 6.8 +/- 1.4 cm). Mean age was 74 years. Ten patients underwent elective repair within the first 2 weeks after the index CT scan (mean, 4 days), precluding adequate observation for early rupture. None had intraoperative signs of rupture. Early rupture: 2 of the 29 remaining patients ruptured within 72 hours of the CT scan, for a positive predictive value of 6.9%. One additional patient ruptured 7 months later after declining an early intervention. No Rupture: 26 patients were observed an average of 246 days (range, 14 days to 3 years) without evidence of rupture. Fourteen were repaired electively 2 weeks to 3 years after the index CT scan, and 12 never underwent repair, mostly because of severe associated comorbidities, and were observed a mean of 394 days without rupture. Although they should be taken seriously, CT signs of "impending rupture'' alone are poor predictors of short-term aortic aneurysm rupture, and alternative terminology is needed until better predictors can be identified.

Carotid artery stenting in octogenarians is associated with increased adverse outcomes.

BACKGROUND: Carotid artery stenting is an increasingly common endovascular treatment of carotid artery stenosis advocated in high-risk patients despite reports of increased adverse periprocedural outcomes in patients aged >80 years. We sought to evaluate our single institution experience with octogenarians and whether they have an increased incidence of major complications with carotid artery stenting. METHODS: Three hundred eighty-six patients, including 260 patients from 10 regulatory trials, who underwent carotid artery stenting between June 1996 and March 2004 for symptomatic or asymptomatic carotid stenosis were reviewed from a prospectively maintained database. Periprocedural (< or =30 days after carotid artery stenting) cerebrovascular accident, transient ischemic attack, myocardial infarction, and death outcomes were compared between 87 octogenarians and 295 nonoctogenarians. Univariate and multivariate analysis was performed for confounding factors. Kaplan-Meier analysis of stroke and death outcomes was performed for a 1-year follow-up. RESULTS: All adverse outcomes were significantly higher in octogenarians compared with younger patients: 30-day stroke rate, 8.0% vs 2.7% (P = .02); 30-day stroke, myocardial infarction, or death, 9.2% vs 3.4% (P = .02). Cohorts were similar in terms of gender, comorbidities, antiplatelet medications, symptomatic status, and use of cerebral protection. Octogenarians had a greater incidence of contralateral internal carotid artery occlusion (26% vs 12%, P = .001), atrial fibrillation (21% vs 8%, P = .001), and congestive heart failure (28% vs 15%, P = .007), but a lower incidence of hypercholesterolemia (53% vs 72%, P = .001) and active smoking (8% vs 24%, P = .001). Multivariate analysis of 30-day major adverse outcomes demonstrated an association between age > or =80 and adverse outcome (odds ratio, 2.85; P = .043) as well as a protective effect of the preprocedural use of aspirin (odds ratio, 0.30, P = .027). At 1-year follow-up, only 75% of octogenarians and 87% of nonoctogenarians were free from stroke, myocardial infarction, or death (P = 005, Kaplan-Meier analysis). CONCLUSIONS: Octogenarians undergoing carotid artery stenting are at higher risk than nonoctogenarians for periprocedural complications, including neurologic events and death. Major event-free survival at 1 year is also significantly better in nonoctogenarians. These risks should be weighed when considering carotid stenting in elderly patients.

Determining in-stent stenosis of carotid arteries by duplex ultrasound criteria.

PURPOSE: To develop customized duplex ultrasound criteria for assessment of in-stent restenosis in the carotid arteries. METHODS: A retrospective review was conducted of 605 patients who underwent carotid artery stenting (CAS) from July 1996 to August 2004 at a single institution. Data on the stented carotid artery were accumulated from patients who had carotid angiography and duplex ultrasound (US) within 30 days of each other. Preliminary review found 118 pairs of ultrasound scans and angiograms in stented carotid arteries. Peak systolic velocity (PSV), end-diastolic velocity (EDV), and internal carotid artery to common carotid artery ratio (ICA/CCA) were examined. Angiographic stenosis was graded by NASCET criteria and compared to velocity parameters at clinically relevant levels of stenosis. The Student t test was used to compare similarly obtained data from 41 nonstented carotid arteries. RESULTS: PSV, ICA/CCA ratio, and EDV increased to a greater degree in stented arteries with stenosis. In 50% to 69% stenotic arteries, mean ICA/CCA ratio was 4.74+/-0.61 in stented versus 3.68+/-0.24 in nonstented carotid arteries (p = 0.043). In arteries with > or = 70% stenosis, there were increases in PSV (475+/-22 versus 337+/-26 cm/s, p = 0.001), EDV (172+/-23 versus 122+/-8 cm/s, p = 0.043), and the ICA/CCA ratio (8.18+/-2.19 versus 5.11+/-0.66, p = 0.063) in stented versus nonstented arteries, respectively. To detect > or = 70% angiographic stenosis, PSV > or = 350 cm/s had 100% sensitivity, 96% specificity, 55% positive predictive value (PPV), and 100% negative predictive value (NPV); an ICA/CCA ratio > or = 4.75 had 100% sensitivity, 95% specificity, 50% PPV, and 100% NPV. To predict > 50% stenosis, combining PSV > or = 225 cm/s and ICA/PCA ratio > or = 2.5 increased sensitivity (95%), specificity (99%), PPV (95%), NPV (99%), and accuracy (98%). CONCLUSIONS: PSV and ICA/CCA increase with stenosis to a greater extent in stented carotid arteries, necessitating revision of existing US criteria to follow CAS patients. To determine > or = 70% in-stent stenosis, PSV > or = 350 cm/s and ICA/CCA ratio > or = 4.75 are sensitive criteria. To determine > or = 50% stenosis, combining PSV > or = 225 cm/s and ICA/PCA ratio > or = 2.5 is optimal.

Carotid endarterectomy remains the standard of care, even in high-risk surgical patients.

OBJECTIVE: This study tested the hypothesis that high-risk patients can undergo carotid endarterectomy without associated increased risk of stroke, transient ischemic attack (TIA), or death. SUMMARY BACKGROUND DATA: Carotid endarterectomy (CEA) has clearly been shown to be effective in reducing the risk of stroke in selected symptomatic and asymptomatic patients with extracranial carotid stenosis. However, recently, carotid angioplasty with stenting (CAS) has been suggested as an alternative treatment in high-risk surgical patients. METHODS: Medical records for consecutive patients who underwent CEA from 1996 to 2001 were reviewed for demographics, medical history, and hospital course. High-risk patients were defined as those experiencing a myocardial infarction (MI) or an exacerbation of congestive heart failure (CHF) within 4 weeks before CEA; unstable angina; steroid-dependent chronic obstructive pulmonary disease (COPD); prior ipsilateral CEA, neck dissection or irradiation; high carotid bifurcation; and those with combined cardiac-carotid procedures. Poor postoperative outcome was defined as stroke, TIA, or death within 30 days. Univariate, multivariate, and Kaplan-Meier analysis were used as appropriate. RESULTS: Four hundred twenty-nine patients underwent 499 CEAs, of which 84 (17%) were considered high risk. The overall stroke-death rate among all patients was 2.8%. A total of 11 postoperative strokes (2.2%), 7 TIAs (1.4%), and 3 deaths (0.6%) occurred within 30 days after surgery. There was no difference in 30-day poor outcome between high- and low-risk patients (4.8% vs. 4.1%, P = 0.77). When these risk factors were assessed independently, those with recent MI were at higher risk for poor outcome (odds ratio [OR], 13.3; 95% confidence interval [CI], 2.2-82.0; P = 0.03). Multivariate analysis also revealed that a history of contralateral stroke or TIA conferred an increased risk of poor outcome (OR, 3.0; 95% CI, 1.1-8.4; P = 0.02), whereas use of preoperative angiotensin-converting enzyme inhibitors was associated with reduced risk (OR, 0.36; 95% CI, 0.11-1.0; P = 0.05), as was a history of hyperlipidemia (OR, 0.33; 95% CI, 0.13-0.87; P = 0.03). By log-rank analysis, 12-month survival was significantly worse in the high-risk group as compared with the low-risk (96% vs. 91%, P = 0.03). CONCLUSIONS: Patients considered a surgical high risk can undergo CEA without any worse outcome compared with those patients deemed low risk. The benefit of CAS will likely be marginal, and only controlled clinical trials will be able to determine if certain subgroups demonstrate improved outcome with CAS. Carotid endarterectomy remains the standard of care, even in high-risk surgical patients.

Extracorporeal life support for severe acute respiratory distress syndrome in adults.

OBJECTIVE: Severe acute respiratory distress syndrome (ARDS) is associated with a high level of mortality. Extracorporeal life support (ECLS) during severe ARDS maintains oxygen and carbon dioxide gas exchange while providing an optimal environment for recovery of pulmonary function. Since 1989, we have used a protocol-driven algorithm for treatment of severe ARDS, which includes the use of ECLS when standard therapy fails. The objective of this study was to evaluate our experience with ECLS in adult patients with severe ARDS with respect to mortality and morbidity. METHODS: We reviewed our complete experience with ELCS in adults from January 1, 1989, through December 31, 2003. Severe ARDS was defined as acute onset pulmonary failure, with bilateral infiltrates on chest x-ray, and PaO2/fraction of inspired oxygen (FiO2) ratio < or =100 or A-aDO2 >600 mm Hg despite maximal ventilator settings. The indication for ECLS was acute severe ARDS unresponsive to optimal conventional treatment. The technique of ECLS included veno-venous or veno-arterial vascular access, lung "rest" at low FiO2 and inspiratory pressure, minimal anticoagulation, and optimization of systemic oxygen delivery. RESULTS: During the study period, ECLS was used for 405 adult patients age 17 or older. Of these 405 patients, 255 were placed on ECLS for severe ARDS refractory to all other treatment. Sixty-seven percent were weaned off ECLS, and 52% survived to hospital discharge. Multivariate logistic regression analysis identified the following pre-ELCS variables as significant independent predictors of survival: (1) age (P = 0.01); (2) gender (P = 0.048); (3) pH < or =7.10 (P = 0.01); (4) PaO2/FiO2 ratio (P = 0.03); and (5) days of mechanical ventilation (P < 0.001). None of the patients who survived required permanent mechanical ventilation or supplemental oxygen therapy. CONCLUSION: Extracorporeal life support for severe ARDS in adults is a successful therapeutic option in those patients who do not respond to conventional mechanical ventilator strategies.