Faculty Bibliography

Mesenteric ischemia (MI) is caused by compromised blood flow to the arteries supplying the small and large intestine. Acute occlusive mesenteric ischemia (AMI) presents with the abrupt onset of severe abdominal pain, which if not diagnosed and treated immediately can cause bowel necrosis and prove fatal. Chronic occlusive mesenteric ischemia (CMI) is usually a longstanding process characterized by postprandial abdominal pain, progressive food intolerance, and weight loss. If untreated, CMI can lead to progressive disability and failure to thrive. This review article highlights the clinical and radiologic diagnosis of acute mesenteric ischemia and CMI and compares their treatment with surgical revascularization and the less invasive alternative of mesenteric artery angioplasty and stenting.

Limited information on a correlation between carotid stump pressure and cerebral oximetry changes associated with cross-clamping of carotid vessels during carotid endarterectomy (CEA) prompted us to prospectively evaluate 38 consecutive CEAs in 37 patients. The authors used the INVOS-4100 cerebral oximeter to measure cerebral oximetry (cerebral oxygen saturation) before (t1) and after (t2) cross-clamping along with carotid stump pressure. All patients had CEA under general anesthesia with the routine use of a Javid shunt. Cross-clamping (t1 vs. t2) resulted in statistically significant changes (p < 0.0001) on the operated side of 6.03 units or a percent change of 9.2% when analyzed using the nonparametric signed-rank test. The nonoperated side had insignificant change (p = 0.71). Spearman correlation analysis revealed significant correlation (r = -0.63) between cerebral oximetry changes on the operated side and carotid stump pressure such that a larger change in cerebral oximetry due to cross-clamping was strongly and significantly correlated with lower carotid stump pressure. Using regression analysis, stump pressures of 25 and 50 mm Hg were predicted by cerebral oximetry changes of 28.5 or 8.8 units, respectively. This is equivalent to a percent change from baseline (t1) of 41.1% or 13.1%, respectively. Taken together, these findings suggest that cerebral oximetry can be used as an alternative to carotid stump pressure to provide noninvasive, inexpensive, and continuous real-time monitoring during CEA.

Routine patch angioplasty after carotid endarterectomy (CEA) is believed to decrease the incidence of recurrent stenosis. The results of autogenous vein, Dacron, and PTFE used as a patch material have been described. Bovine pericardium has more recently been introduced as a patch material. We studied 61 of 73 consecutive patients who underwent isolated CEA with pericardial patch angioplasty to determine the incidence of restenosis and variables associated with restenosis. All patients had intraoperative completion duplex examination performed, and no patient had residual stenosis or anatomic defects at the end of the procedure. All procedures were performed under general anesthesia with the use of a Javid shunt. Mean age was 72.8 +/- 7.8 years, 41% were female, and 62% were asymptomatic. Hypertension was present in 72%, elevated cholesterol in 80%, and history of coronary artery disease in 44%. Recurrent stenosis of >50% was considered to be significant. Our study focuses on 61 of 73 patients who had follow-up duplex ultrasound data available. There were no perioperative neurologic events, reoperations for bleeding, or deaths. Mean duplex follow-up available in 61 patients was 13.1 +/- 5.1 months. Thirty-six patients had 1-15% stenosis, 15 patients had 16-49%, and 10 patients had 50-79%. In the 50-79% group, the mean systolic velocity was 154 +/- 25 cm/sec and the mean end diastolic velocity (EDV) was 36 +/- 16 cm/sec. The highest EDV in the 50-79% group was 56 cm/sec. No patients had stenosis in the 80-99% range. There were no late neurologic events and no late reinterventions. Kaplan-Meier restenosis-free survival at 1 year was 95.6%. Significant univariate predictors of recurrent stenosis of >50% were younger age (68 vs. 74 years, p = 0.04) and presence of preoperative symptomatic disease (35% vs. 5%, p = 0.004). Stepwise multiple logistic regression indicated the most significant predictor of restenosis was the presence of preoperative symptoms (p = 0.008). Stepwise Cox regression analysis also showed preoperative symptomatic status was the only significant factor for restenosis (p = 0.019), with a relative risk of 6.65 and a 95% confidence interval of 1.36-32.4. In conclusion, pericardial patch angioplasty is associated with minimal early adverse events. Restenosis with pericardial patch angioplasty is not uncommon, but high-grade restenosis did not occur in this study. The presence of preoperative symptoms and younger age were the most significant predictors of restenosis.

A rare presentation of arterial thoracic outlet syndrome (TOS) is described in a young woman. Arterial TOS caused by a cervical rib produced acute upper extremity ischemia due to subclavian artery aneurysm formation. Clinical presentation also included left hemiparesis caused by right subclavian artery thrombosis and retrograde embolization of thrombus via the common carotid artery to the right middle cerebral artery distribution. Surgical repair of the subclavian artery was performed, but permanent neurologic deficit remained. Acute thrombosis of the right subclavian artery can produce cerebrovascular complication. The assessment of such risk in patients with arterial TOS is warranted and the arterial lesion corrected surgically.

Popliteal artery aneurysms account for 85% of all peripheral aneurysms and are frequently associated with abdominal aortic aneurysms. Up to 75% of all popliteal artery aneurysms are discovered in symptomatic patients who present with arterial insufficiency, leg swelling, or pain. Popliteal artery aneurysms can be diagnosed with duplex ultrasonography. Aneurysm repair should be considered for all symptomatic patients with rest pain or limb-threatening symptoms. Asymptomatic aneurysms larger than 2 cm should also be treated to prevent the development of limb-threatening ischemia and assure better surgical bypass graft patency and longer freedom from amputation. Conventional aneurysm repair consists of either opening the aneurysm sac and interposing a bypass graft or aneurysm ligation combined with bypass grafting. If the aneurysm sac is left intact, side branch perfusion may persist and the aneurysm may continue to enlarge and can rupture. Endovascular popliteal aneurysm repair has not demonstrated clinical equipoise to standard surgery but may be advantageous in select high-risk patients.

The authors reviewed a 2-year experience with abdominal aortic aneurysm (AAA) repair to determine if patients who were excluded from endovascular aneurysm repair (EVAR) because of anatomic criteria (Group III) represented a higher risk for subsequent open aneurysm repair than either patients undergoing EVAR (Group II) or those patients who preferentially underwent open repair (Group I). Between January 2001 and December 2003, 107 patients underwent AAA repair. Open repair was recommended in patients <70 years of age and without significant comorbidities (Group I). There were 35 patients in Group I; 72 patients were evaluated for EVAR; 29 patients underwent EVAR (Group II), and 43 were excluded and underwent open repair (Group III). Exclusion criteria were those recommended by the graft manufacturers. Patients in Group I were significantly younger than those in Groups II and III (p < 0.0001). Gender, incidence of diabetes, and hypertension were similar in all groups. Patients in Group III had a greater incidence of coronary artery disease (CAD) than those in Groups I and II, trending toward statistical significance (p = 0.06). Aneurysm size in Group II was statistically smaller than in Group I or III. Group III had significantly more complications (25.6% vs 5.7% and 6.9%) than either Group I or II (p < 0.015). Cardiac complications were similar in all groups. Three patients in Group III required prolonged intubation and 3 in Group III developed renal insufficiency. A history of CAD was predictive of complications (21.8% vs 5.8%, p < 0.024), as was inclusion in Group III. There were 2 deaths in this series, both in Group III. Length of stay was significantly less in Group II (4.17 +/-2.36 days) than in Group I (6.57 +/-1.84 days) or Group III (12.30 +/-9.82 days) (p = 0.0001). Open aneurysm repair can be safely performed in younger good-risk patients (Group I) with results equivalent to EVAR (Group II) but with slightly longer length of stay (LOS). In older patients with suitable anatomy EVAR can be performed with minimal morbidity and short LOS. Older patients not suitable for EVAR (Group III) constitute a higher risk group of patients because of increased incidence of CAD and the need for more complex repairs. However, the mortality rate in this group was only 4.6%.

Cerebral oximetry is a simple method of measuring regional cerebral oxygen saturation (rSO(2)). One promising application is its use during carotid endarterectomy (CEA) to help minimize the risk of perioperative stroke. The authors used the INVOS-4100 cerebral oximeter at several steps during CEA to measure the effect of carotid clamping and shunting on rSO(2). The authors prospectively evaluated 42 consecutive CEAs in 40 patients. All had CEA under general anesthesia with the routine use of a Javid shunt. The INVOS-4100 oximeter was used to measure rSO(2) before clamping (t1), after clamping but before shunting (t2), 5 minutes after shunt insertion (t3), and after patch closure with reestablished flow (t4). The Wilcoxon signed-rank and rank-sum tests were used for analysis. Clamping of the internal carotid artery (t1 vs t2) resulted in a drop of ipsilateral rSO(2) by -12.3% (p < 0.001). Shunt insertion (t2 vs t3) increased rSO(2) by 10.9% (p < 0.001). Contralateral rSO(2) for the same time periods was insignificant. Patients with preoperative neurologic symptoms had a greater decrease in rSO(2) after clamping (-18.4%) compared with a decrease of -10.4% in asymptomatic patients (p = 0.037). Cerebral oximetry monitoring is simple and inexpensive. The study showed statistically significant changes in rSO(2) as a result of clamping and shunting of the carotid artery. Symptomatic patients had a greater drop in rSO(2).

The concept of a "high-risk" carotid endarterectomy patient has been suggested in an effort to justify the application of carotid angioplasty and stenting outside of clinical trials. Contemporary results of carotid endarterectomy in this subgroup of patients would argue against the existence of a high-risk patient. Until randomized prospective trials establish the role of carotid angioplasty and stenting in carotid bifurcation disease, this new technology should be restricted to recurrent and radiation-induced disease.

The aim of this study was to evaluate the current management of acute mesenteric ischemia secondary to thrombotic or embolic occlusion of visceral vessels in a community teaching hospital. Between October 1997 and July 2000, a review of all hospital discharges revealed 83 patients with a discharge diagnosis of "acute vascular insufficiency-intestine." Among these 83 patients, 22 cases of acute mesenteric ischemia were confirmed. Management of these 22 patients was divided into 2 groups for analysis. In Group A, 14 patients were aggressively treated with visceral angiography (n=10), visceral artery bypass (n=8), visceral embolectomy (n=4), and bowel resection (n=7). In 8 of 14 of these patients, surgical intervention occurred in less than 24 hours from presentation. In Group B, 8 patients were managed with supportive care because of advanced age (mean age = 86 +/- 7 years), comorbid conditions, or patient and family preference. Postoperative morbidity in Group A consisted of cardiac events (n=3), pulmonary insufficiency (n=5), and prolonged gastrointestinal tract dysfunction (n=3). Twelve of 14 patients in Group A survived and were discharged, whereas only 2 of 8 patients in Group B survived and were discharged from the hospital. Although the literature suggests that there can be a significant delay in the diagnosis and treatment of acute mesenteric ischemia, the early recognition and aggressive treatment of acute mesenteric ischemia resulted in a good survival rate. Supportive management of very elderly and debilitated patients needs to be considered on a case-by-case basis. Although the outlook for such patients is dismal, survivors are possible as demonstrated by this series.

OBJECTIVE: It has been proposed that patients whose conditions do not meet North American Symptomatic Carotid Endarterectomy Trial inclusion criteria or have anatomic risk factors constitute a "high-risk" group for carotid endarterectomy (CEA) and might be candidates for primary carotid angioplasty stenting. Our objective was to review a consecutive series of isolated CEAs, identify the number of such patients at high risk, and determine whether their operations were associated with increased complication rate. METHODS: Consecutive isolated CEAs performed between June 1996 and June 2001 were reviewed. High-risk comorbidities included: age 80 years or more (n = 80), New York Heart Association class III/IV angina (n = 16), Canadian class III/IV heart failure (n = 4), myocardial infarct 6 months or less (n = 11), steroid-dependent or oxygen-dependent pulmonary disease (n = 4), and creatinine level of 3 or more (n = 13). Anatomic high risk was defined by: contralateral occlusion (n = 66), lesion above C(2) or requirement of digastric division (n = 53), reoperation (n = 29), and neck radiation (n = 3). Statistical analysis was with chi(2) analysis. RESULTS: Of 788 patients reviewed, 228 (29%) were classified as high risk by one or more of the previous criteria (63% comorbidity, 28% anatomy, 9% both). Presence of preoperative neurologic symptoms and postoperative results were similar across all patient groups. The total stroke and death rate was 1.1% for all the patients. Six patients had postoperative strokes (0.8%), and three patients died of myocardial infarcts (0.4%). The stroke and death rate was 1.3% in the high-risk group as compared with 1.1% in the normal-risk group (P =.51). CONCLUSION: The concept of the high-risk CEA must be critically reexamined. Although 29% of patients for CEA were high risk as defined by others, we found no evidence that this influenced the results after CEA. Patients with significant medical comorbidities, contralateral carotid occlusion, and high carotid lesions can undergo operation without increased complications. If a high-risk group exists, it is small and restricted to reoperation or radiated neck (4% in this series). With this possible exception, carotid angioplasty stenting should be restricted to randomized clinical trials.