Gerald B. Zelenock

Operative mortality rates for intact and ruptured abdominal aortic aneurysms in Michigan: an eleven-year statewide experience.

Abstract Purpose: The purposes of this study were (1) to determine the current population-based mortality rate for the surgical treatment of abdominal aortic aneurysms (AAA) in Michigan, (2) to document changes in mortality rates over 11 years, and (3) to identify risk factors for operative mortality. Methods: A statewide database provided clinical information on all Michigan hospital admissions with a diagnosis of AAA from 1980 to 1990. The mortality rate analysis included all admissions with a primary diagnosis of AAA that underwent repair. Determination of diagnoses and comorbidities were based on International Classification of Diseases-ninth revision-Clinical Modification codes. Results: Conventional surgical repairs were performed on 8185 intact and 1829 ruptured AAA. Hospital mortality rates accompanying operation for intact AAA decreased from 13.6% in 1980 to 5.6% in 1990 ( p p p Conclusion: Despite a dramatic drop in surgical mortality rates, repair of intact AAA remains a formidable undertaking. This population-based series documents a substantially higher mortality rate than most selected series. The unchanged mortality rate for ruptured AAA suggests that development of better algorithms to identify those AAA most apt to rupture and earlier intervention in those instances is likely to improve patient survival rates. (J VASC SURG 1994;19:804-17.)

Evaluation of a cerebral oximeter as a monitor of cerebral ischemia during carotid endarterectomy.

BackgroundStroke is an important contributor to perioperative morbidity and mortality associated with carotid endarterectomy (CEA). This investigation was designed to compare the performance of the INVOS-3100 cerebral oximeter to neurologic function, as a means of detecting cerebral ischemia induced by carotid cross-clamping, in patients undergoing carotid endarterectomy with cervical plexus block. MethodsNinety-nine patients undergoing 100 CEAs with regional anesthesia (deep or superficial cervical plexus block) were studied. Bilateral regional cerebrovascular oxygen saturation (rSO2) was monitored using the INVOS-3100 cerebral oximeter. Patients were retrospectively assigned to one of two groups: those in whom a change in mental status or contralateral motor deficit was noted after internal carotid clamping (neurologic symptoms; n = 10) and those who did not show any neurologic change (no neurologic symptoms; n = 90). Data from 94 operations (neurologic symptoms = 10 and no neurologic symptoms = 84) were adequate for statistical analyses for group comparisons. A relative decrease in ipsilateral rSO2 after carotid occlusion (calculated as a percentage of preocclusion value) during all operations (n = 100) was also calculated to determine the critical level of rSO2 decrease associated with a change in neurologic function. ResultsThe mean (± SD) decrease in rSO2 after carotid occlusion in the neurologic symptoms group (from 63.2 ± 8.4% to 51.0 ± 11.6%) was significantly greater (P = 0.0002) than in the no neurologic symptoms group (from 65.8 ± 8.5% to 61.0 ± 9.3%). Logistic regression analysis used to determine if a change in rSO2, calculated as a percentage of preclamp value, could be used to predict change in neurologic function was highly significant (likelihood ratio chi-square = 13.7;P = 0.0002). A 20% decrease in rSO2 reading from the preclamp baseline, as a predictor of neurologic compromise, resulted in a sensitivity of 80% and specificity of 82.2%. The false-positive rate using this cutoff point was 66.7%, and the false-negative rate was 2.6%, providing a positive predictive value of 33.3% and a negative predictive value of 97.4%. ConclusionMonitoring rSO2 with INVOS-3100 to detect cerebral ischemia during CEA has a high negative predictive value, but the positive predictive value is low.

Gender differences in abdominal aortic aneurysm prevalence, treatment, and outcome

PURPOSE The purpose of this study was to investigate gender differences in the management of and outcome of surgery for abdominal aortic aneurysms (AAA). METHODS Hospital discharge data from all acute care hospitals in Michigan, as compiled in the Michigan Inpatient Data Base, were retrospectively analyzed to assess sex differences in regard to AAA prevalence, treatment, and surgical outcome from 1980 to 1990. This population database included 11,512 women and 29,846 men 50 years of age and older with diagnoses of intact or ruptured AAA. RESULTS Hospitalizations for intact or ruptured AAA were approximately five times more common among men compared with women. After controlling for age and year of surgery, men were 1.8 times as likely as women to have an intact AAA treated surgically and 1.4 times as likely to have a ruptured AAA treated surgically (95% confidence intervals, 1.7 to 1.9 and 1.2 to 1.7, respectively). Women who had operations for intact AAA had a 1.4 times greater risk of dying compared with men, and women who had operations for ruptured AAA had a 1.45 times greater risk of dying, after controlling for other predictors of death (95% confidence intervals, 1.14 to 1.73 and 1.10 to 1.90, respectively). CONCLUSIONS In a population-based statewide experience, women who had intact or ruptured AAA were less likely than men to undergo aortic reconstruction and, when they did, were less likely than men to survive to discharge.

Clinical characteristics and surgical management of vascular complications in patients undergoing cardiac catheterization: Interventional versus diagnostic procedures☆

The purpose of this report is to define the clinical characteristics and outcome of surgical management of vascular complications after interventional cardiac catheterization and to contrast them to those after diagnostic cardiac catheterization. From October 1985 to December 1989, 101 patients were treated for 106 vascular complications after 1866 interventional and 5046 diagnostic cardiac catheterizations at the University of Michigan Medical Center. Interventional catheterizations resulted in 69 vascular complications in 64 patients (frequency 3.4%). The most common interventions included coronary angioplasty (34), of which 10 required percutaneous partial cardiopulmonary bypass, intraaortic balloon pump placement (14), and aortic valvuloplasty (11). Interventional catheter-related complications included hemorrhage (33), arterial thrombosis (18), pseudoaneurysm formation (12), catheter embolization (2), thromboembolism (2), as well as arteriovenous fistula, pseudoaneurysm, and arterial dissection (1 each). Fifteen of these 69 patients (24%) had suffered acute myocardial infarction just before their catheterization. Surgical repair was performed under local anesthesia in 70% of patients. Major vascular reconstructions were required in 9% of patients. Three percent of the involved lower extremities had to be amputated because of complications occurring after arterial puncture. Eight percent of the patients incurring vascular complications after interventional procedures died after operation. Diagnostic catheterizations resulted in 37 vascular complications in 37 patients (frequency 0.7%). In contrast to diagnostic cardiac catheterization, vascular complications after interventional cardiac catheterization occurred more frequently, were most often due to hemorrhage at the vascular access site, and occurred in high-risk, critically ill patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal revascularization for recurrent pulmonary edema in patients with poorly controlled hypertension and renal insufficiency: A distinct subgroup of patients with arteriosclerotic renal artery occlusive disease

Recurrent pulmonary edema in patients with poorly controlled hypertension and renal insufficiency appears to be a marker of bilateral renal artery occlusive disease. The effectiveness of renal revascularization to prevent recurrent pulmonary edema in this distinct subgroup with renal artery occlusive disease was analyzed in 17 consecutive patients treated at the University of Michigan Hospital between 1984 and 1990. Their mean preoperative blood pressure was 207/110 mm Hg, and mean serum creatinine clearance was 3.8 mg/dl. Pulmonary edema occurred despite evidence of normal ventricular function in 65% of these patients. Bilateral renal artery occlusive disease affected 94% of the patients, and 54% had an occluded renal artery. Renal revascularization was accomplished by iliorenal bypass (41%), aortorenal bypass (29%), endarterectomy (24%), and transluminal angioplasty (6%). Contralateral nephrectomy (41%) and concomitant aortic reconstruction (24%) were also required frequently. No postoperative deaths occurred, and no patient had early postoperative pulmonary edema. Control of hypertension was improved in all patients, two of whom were discharged from the hospital on no antihypertensive medications. Two of the three patients requiring dialysis before operation were able to discontinue dialysis after operation. Late follow-up (mean, 2.4 years) revealed hypertension to be cured in one patient (6%), and improved in 16 patients (94%). Pulmonary edema occurred in one patient during late follow-up. Late follow-up showed renal function (mean creatinine, 1.7 mg/dl) to be improved in 77%, stable in 12%, and worse in two patients; one required dialysis. A single episode of pulmonary edema in a patient with poorly controlled hypertension and renal insufficiency should prompt consideration of this clinical syndrome and early diagnostic angiography.(ABSTRACT TRUNCATED AT 250 WORDS)

Gadolinium-enhanced magnetic resonance angiography of abdominal aortic aneurysms.

PURPOSE The objective of this study was to assess the usefulness of gadolinum-enhanced magnetic resonance angiography (MRA) for defining anatomic features relevant to performing aortic surgery for aneurysmal disease. METHODS Anatomic data defined by MRA, including abdominal aortic aneurysm (AAA) size and character, as well as the status of the celiac, mesenteric, renal, and iliac arteries, were correlated with angiography, ultrasonography, computed tomography, or operative data in 43 patients. Five MRA sequences were obtained in an hour-long examination optimized for aortoiliac, splanchnic, and renal artery imaging at 1.5 T in a body coil. Four of the sequences were performed during or after infusion of gadolinium to improve image quality. RESULTS MRA correctly defined the maximum aneurysm diameter, as well as its proximal and distal extent in all patients. MRA detected 33 of 35 significant stenoses among 153 splanchnic, renal, or iliac branches examined (sensitivity = 94% and specificity = 98%). MRA did not resolve the degree of aortic branch stenotic disease sufficiently to precisely grade its severity. MRA did not reliably define the status of the inferior mesenteric artery, lumbar arteries or internal iliac arteries. One ruptured AAA and one inflammatory AAA were correctly diagnosed by MRA. No patient had a contrast reaction or contrast-induced renal toxicity related to administration of gadolinium. CONCLUSION Gadolinium-enhanced MRA of AAA provides appropriate, essential anatomic information for aortic reconstructive surgery in a 1-hour examination devoid of contrast-related renal toxicity or catheterization-related complications attending conventional arteriography.

Celiac artery aneurysms: Historic (1745-1949) versus contemporary (1950-1984) differences in etiology and clinical importance

Celiac artery aneurysms were encountered in nine patients, ranging in age from 39 to 76 years, at the University of Michigan Medical Center between 1961 and 1983. Developmental defects and atherosclerosis were etiologic factors in six cases. Four patients were without symptoms, whereas five experienced abdominal pain, including one with a ruptured aneurysm. Eight patients were subjected to surgical treatment; no deaths occurred and symptoms were resolved in all patients. A literature review of 108 celiac artery aneurysms revealed two distinct subgroups. Among 60 celiac artery aneurysms encountered before 1950, representing the historic era, 40% were infectious (usually luetic), 7% were traumatic, and 52% were of undetermined cause. Most were symptomatic, 87% ruptured, and 95% were diagnosed at postmortem examination. The contemporary era since 1950 consisted of 48 cases, including nine in the Michigan experience. Congenital or developmental medial defects of the arterial wall and atherosclerosis were the most common causes of aneurysms. Most aneurysms in the contemporary period were either asymptomatic or accompanied by vague abdominal discomfort. Rupture affected 13% of those aneurysms. Operative therapy was successfully undertaken in 91% of 43 patients during the contemporary era, including eight in the present series.

Insulin administration protects neurologic function in cerebral ischemia in rats.

Hyperglycemia exacerbates neurologic damage in clinical and experimental central nervous system ischemia. The purpose of our study was to determine if insulin administration before significantly alters neurologic deficit and survival after ischemia using a newly developed rat cerebral ischemia model. One hour before the onset of ischemia, 40 200-300-g Sprague-Dawley rats received intraperitoneal injections of either 1 ml normal saline or 0.4, 0.5, or 0.6 units regular insulin in 1 ml normal saline. Rats were then intubated and ventilated with 1-1.5% halothane. The aortic arch was exposed, and snares were placed on the innominate, left carotid, and left subclavian arteries. A 20-minute occlusion was begun, and anesthesia was discontinued. Baseline plasma glucose concentration was similar (p = 0.48, Students t test) in both groups, but it subsequently was significantly lower in the 0.4 unit insulin-treated group up to 4 hours after occlusion (p less than or equal to 0.0035, Students t test). Neurologic deficit was scored on a 50-point scale (0 = normal, 50 = severe deficit) 1, 4, 18, and 24 hours after occlusion. In the 0.4 unit insulin-treated group the neurologic deficit score was significantly lower than in the saline-treated group 1, 4, 18, and 24 hours after occlusion (p less than or equal to 0.005, Students t test). Survival was significantly higher (p = 0.001) in the 0.4 unit insulin-treated (1.7 unit/kg dose) group than in the saline-treated group. No rats died when preocclusion plasma glucose concentration was between 65 and 175 mg/dl.(ABSTRACT TRUNCATED AT 250 WORDS)

Pediatric renovascular hypertension: A thirty-year experience of operative treatment

PURPOSE This study was undertaken to characterize the changing operative treatment of pediatric renovascular hypertension and subsequent outcomes in a 30-year experience at a single institution. METHODS Clinical data were analyzed on 57 pediatric patients, 24 girls and 33 boys, ranging in age from 10 months to 17 years, who underwent operations for renovascular hypertension from 1963 to 1993 at the University of Michigan. Renal artery disease included atypical medial-perimedial dysplasia, often with secondary intimal fibroplasia (88%), and inflammatory mural fibrosis (12%). Abdominal aortic narrowings affected 15 patients. Data were categorized into three chronologic eras (I:1963-1972, II:1973-1980, and III:1981-1993) to allow identification of therapeutic trends. RESULTS Primary surgical procedures were undertaken 74 times. Ex vivo reconstruction was necessary once. Primary operations included aortorenal bypass with autogenous vein grafts (n = 26) or internal iliac artery grafts (n = 7); iliorenal bypass with vein grafts (n = 2); renal artery resection beyond the stenosis and reimplantation into the aorta (n = 10), the main renal artery (n = 2), an adjacent segmental renal artery (n = 3), or the superior mesenteric artery (n = 3); renal artery resection and reanastomosis (n = 3); focal renal arterioplasty (n = 2); operative dilation (n = 7); splenorenal bypass (n = 2); and primary nephrectomy (n = 7). Among 23 primary operations performed in era I, 56.5% were aortorenal bypasses with vein grafts, but in era III this form of revascularization represented only 3% of 33 primary operations. No reimplantations were performed in era I, whereas reimplantations accounted for 51.5% of era III procedures. Thirteen patients underwent staged or concomitant aortic reconstructions with thoracoabdominal aortoaortic bypass grafts (n = 5) or patch aortoplasty (n = 8). Fourteen patients underwent a total of 20 secondary operations, including seven secondary nephrectomies. Operative therapy benefited 98% of these children: hypertension was cured in 45 (79%), improved in 11 (19%), and unchanged in one (2%). There were no operative deaths. CONCLUSIONS Contemporary surgical management emphasizes direct reimplantation of main renal arteries into the aorta, reimplantation of segmental arteries into adjacent renal arteries, patch aortoplasty for associated abdominal aortic coarctations, and single-stage revascularizations. Pediatric patients with renovascular hypertension clearly benefit from carefully executed operative therapy.

Atherosclerotic extracranial carotid artery aneurysms.

Twenty-four atherosclerotic extracranial carotid artery aneurysms were encountered in 21 patients during a 25-year period. These represented 46% of all extracranial carotid artery aneurysms diagnosed at the University of Michigan during this period. Neurologic symptoms including amaurosis fugax, transient ischemic attacks, and stroke were present in 50% of the patients. An asymptomatic pulsatile neck mass occurred in 33%. Surgical therapy was undertaken for 18 aneurysms, and nonoperative treatment was pursued in the remaining six aneurysms. Operative therapy included 14 aneurysmectomies and four aneurysmorraphies. There were no surgical deaths. Transient perioperative neurologic deficits affected three of these patients (17%), and one individual (5%) experienced a permanent deficit. Transient cranial nerve deficits occurred in three patients (17%), and a permanent deficit was noted in one patient (5%). During a 7.6-year follow-up period no late strokes occurred among patients who were operated on. Nonoperative therapy was associated with three ipsilateral strokes during a mean follow-up period of 6.3 years. Atherosclerotic extracranial carotid artery aneurysms were associated with an exceptionally high stroke rate (50%) if treated nonoperatively. Prevention of late stroke justifies surgery, although perioperative neurologic deficits may accompany this therapy more often than with nonatherosclerotic carotid artery aneurysms.