Sundt, Thoralf M.

Data from the records of patients who underwent 2223 carotid endarterectomies at the Mayo Clinic between January 1, 1972, and December 31, 1985, were abstracted to compare the effects of isoflurane, enflurane, and halothane on the critical cerebral blood flow (CBF) (i.e., the CBF below which the majority of patients develop EEG ischemic changes within 3 min of carotid occlusion), the incidence of EEG ischemic changes, and the neurologic outcome. In a total of 2196 of these procedures, the patient received one of the three volatile anesthetics and, in 2010 of these, both the EEG and the CBF were monitored. Chronologically, halothane was the primary agent from 1972–1974; enflurane progressively replaced halothane during 1975–1981; and isoflurane was used almost exclusively since 1982. This analysis confirmed a previous study that the critical CBF during isoflurane anesthesia (703 procedures) was approximately 10 ml ± 100 g−1 • min−1, as contrasted to that of approximately 20 ml ± 100 g−1 • min−1 during halothane anesthesia (467 procedures). This analysis also established that the critical CBF during enflurane anesthesia (840 procedures) was approximately 15 ml ± 100 g−1 • min−1. The incidence of EEG ischemic changes was significantly less (P < 0.001) during isoflurane anesthesia (18%) than during either enflurane (26%) or halothane (25%) anesthesia. This difference occurred despite the fact that the preoperative risk status was greater in the patients given isoflurane. There was no difference in neurologic outcome between the three anesthetics, and none was expected, since all patients with EEG changes were immediately shunted, if possible. The authors conclude that relative to halothane and enflurane, isoflurane does offer a degree of cerebral protection for transient incomplete regional cerebral ischemia during carotid endarterectomy.

Background— In the elderly, mitral regurgitation (MR) is frequent, but surgery risks are considered high. Benefits and indications of MR surgery are uncertain in the elderly. Methods and Results— Baseline characteristics, outcome, and trends for surgical results improvement were analyzed in elderly patients (≥75 years of age; n=284) operated on for MR in 1980 to 1995 compared with younger patients (65 to 74 years of age, n=504; and <65 years of age, n=556). Preoperatively, class III to IV symptoms, atrial fibrillation, coronary disease, creatinine, and comorbidity index were more severe in elderly patients (all P <0.002). In the long term after surgery, observed survival stratified by age (≥75, 65 to 74, <65 years) was lower in elderly than in younger patients (at 5 years, 57±3%, 73±2%, and 85±2%, respectively; P <0.001), but ratios of observed to expected survival were similar (83%, 85%, and 88%, respectively). In multivariate analysis adjusted to expected survival, elderly patients showed no difference in life expectancy restoration compared with younger patients (adjusted hazard ratio, 0.89; 95% confidence interval, 0.73 to 1.30; P =0.54). Temporal trends showed that risk of operative mortality, although higher in elderly patients ( P <0.001), declined markedly for all ages (27% to 5% in those ≥75 years of age, P <0.01; 21% to 4% in those 65 to 74 years of age, P <0.01; and 7% to 2% in those <65 years of age, P =0.06), with a parallel decline in low cardiac output and length of hospital stay. Over time, valve repair feasibility increased in all age groups (30% to 84% overall and 31% to 93% in degenerative MR; P <0.0001). Conclusions— Elderly patients undergoing MR surgery display more severe preoperative characteristics and incur higher operative risks than younger patients. However, restoration of life expectancy after surgery is similar in elderly and younger patients, and outstanding recent surgical improvements particularly benefited elderly patients. Thus, elderly patients with MR can now carefully be considered for surgery before refractory heart failure is present.

Background— The clinical profiles and outcomes of patients treated surgically for acute type B aortic dissection (ABAD) are often reported for those in small series or for those cared for at a single institution over a long time period, during which a continuous evolution in techniques has occurred. Accordingly, we sought to evaluate the clinical features and surgical results of patients enrolled in the International Registry of Acute Aortic Dissection by identifying primary factors that influenced surgical outcome and estimating average surgical mortality for ABAD in the current era. Methods and Results— A comprehensive analysis of 290 clinical variables and their relation to surgical outcomes for 82 patients who required surgery for ABAD (from a population of 1256 patients; mean±SD age, 60.6±15.0 years; 82.9% male) and who were enrolled in the International Registry of Acute Aortic Dissection was performed. The overall in-hospital mortality was 29.3%. Factors associated with increased surgical mortality based on univariate analysis were preoperative coma or altered consciousness, partial thrombosis of the false lumen, evidence of periaortic hematoma on diagnostic imaging, descending aortic diameter >6 cm, right ventricle dysfunction at surgery, and shorter time from the onset of symptoms to surgery. Factors associated with favorable outcomes included radiating pain, normotension at surgery (systolic blood pressure 100 to 149 mm Hg), and reduced hypothermic circulatory arrest time. The 2 independent predictors of surgical mortality were age >70 years (odds ratio, 4.32; 95% confidence interval, 1.30 to 14.34) and preoperative shock/hypotension (odds ratio, 6.05; 95% confidence interval, 1.12 to 32.49). Conclusions— The present study provides insights into current-day clinical profiles and surgical outcomes of ABAD. Knowledge about different preoperative clinical conditions may help surgeons in making treatment decisions among these high-risk patients.

AbstractThe results and complications of neurovascular operations in one surgeon's experience during the era of the operating microscope are reviewed in the framework of the pathophysiology of the illness for which they were performed. Overall mortality rate was 5% and morbidity rate 11% in 405 patients with intracranial aneurysms. Morbidity and mortality varied according to preoperative neurological function, location and size of aneurysm, and number of days from last subarachnoid hemorrhage to surgery. Although a delay in operation improved the operative results, there were significant mortality and morbidity among patients awaiting surgery. There were immediate and delayed ischemic complications. In the former group (7% of cases), the cause was clearly attributable to surgical trauma, such as damage to perforating vessels and major vessel occlusion, which was related to size and location of the aneurysm and unrelated to the patient's neurological function or timing of surgery. Delayed ischcmic complications, minor and reversible in 10% of patients, severe in 5%, were related to preoperative neurological function and timing of surgery. These did not occur in any patients operated on for a mass effect from the aneurysm without a subarachnoid hemorrhage.The overall combined major morbidity and mortality for carotid endarterectomy in 681 patients in whom the microscope was not used was 2%, but varied according to medical, neurological, and angiographically determined risk factors. Patients were seldom operated on for lesions that did not produce at least a 70–80% stenosis unless there was angiographie evidence of severe ulccration. All patients were monitored intraoperatively with cerebral blood flow measurements and a continuous electroencephalogram. Retinal artery pressure measurements were performed pre‐operatively and postoperatively. The relationship of these monitoring techniques to the pathophysiology of ischemic symptomatology is reviewed.Preliminary evaluation of 149 extracranial to intracranial bypass procedures for occlusive disease of the carotid system, and of 22 procedures for occlusive disease in the vertebral‐basilar system indicates a patency rate of 95% and 90%, respectively. The effectiveness of these operations was related to the symptomatology for which they were performed. The overall combined morbidity and mortality was 5%, but varied according to preoperative neurological function.There were 59 operations for cerebral arteriovenous malformations (AVM) (38 parenchymal, 1 death; 21 durai, 1 death). Low morbidity and mortality rates were achieved in parenchymal AVMs by not operating on large lesions or those with a thalamic component and, therefore, these results must be placed in that perspective. This conservative approach was justified by the current lack of information concerning the natural history of this illness. In contrast, virtually all durai AVMs were eventually operated on because of the progressive nature of this acquired illness.

Background— The incidence, determinants, and outcome of postoperative atrial fibrillation (AF) after surgery for mitral regurgitation (MR) are poorly defined but may have important implications for timing of mitral valve surgery. Methods and Results— In 762 patients in sinus rhythm with no AF history undergoing MR surgical correction, we examined the rates and prognostic implications of postoperative AF for early AF (within 2 weeks postoperatively) and late AF (>2 weeks after surgery). During postoperative follow-up, 180 patients (24%) experienced new AF (early AF in 136 and late AF in 111). Isolated early AF without recurrence was observed in 69 patients characterized by high angina class and lower left ventricular ejection fraction but no significant left atrial (LA) enlargement. However, overall early AF predicted late AF: 62±5% of patients with early AF had late AF at 10 years compared with 9±1% of patients without early AF ( P <0.0001). Large LA size strongly and independently predicted early AF ( P =0.01) and late AF ( P =0.003). For late AF, the predictive value of an enlarged LA was cumulative to that of early AF. Postoperative AF was associated with an increased subsequently higher risk of stroke or congestive heart failure (adjusted risk ratio=1.46 [1.04 to 2.05], P =0.03). Conclusions— Postoperative AF is common after surgical correction of MR in patients with no prior history of AF and is associated with increased subsequent morbidity. LA enlargement is independently predictive of postoperative AF and as such, should be integrated into the clinical decision-making process in patients with MR.

Background— This study evaluated long-term results of aortic root replacement and valve-preserving aortic root reconstruction for patients with aneurysms involving the aortic root. Methods and Results— Two-hundred three patients aged 53±16 years (mean±SD; 153 male, 50 female) underwent elective or urgent aortic root surgery from 1971 to 2000 for an aortic root aneurysm: 149 patients underwent a composite valve conduit reconstruction, and 54 patients underwent valve-preserving aortic root reconstruction. Fifty patients had Marfan syndrome. In-hospital and 30-day mortality was 4.0% (8/203) overall: for a composite valve conduit procedure, the corresponding value was 4.0% (6/149) and for valve-preserving procedure, 3.7% (2/54) ( P =NS). Morbidity included 3 strokes (1%), 10 perioperative myocardial infarctions (5%), and 8 reoperations for bleeding (4%). Actuarial survival at 5, 10, 15, and 20 years was 93% (95% confidence interval [CI] = 88% to 97%), 79% (95% CI = 71% to 87%), 67% (95% CI = 57% to 79%), and 52% (95% CI = 36% to 69%), respectively. Freedom from reoperation was 72% (95% CI = 54% to 86%) at 20 years. Complications with anticoagulation occurred in 29 patients; with valve thrombosis, in 2; and with hemorrhage, in 27 (4 life threatening and 23 minor). Freedom from thromboembolism was 91% (95% CI = 77% to 98%) at 20 years. Freedom from endocarditis was 99% (95% CI = 92% to 100%) at 20 years. Multivariate analysis revealed preoperative mitral valve regurgitation (+3 to 4) and older age to be significant predictors of late death ( P ≤0.005), and Marfan syndrome, initial valve-preserving aortic root reconstruction, and need for a concomitant procedure at initial operation to be significant predictors of the need for reoperation ( P ≤0.01). Conclusions— Aortic root replacement for aortic root aneurysms can be done with low morbidity and mortality. Composite valve conduit reconstruction resulted in a durable result. There were few serious complications related to the need for long-term anticoagulation or a prosthetic valve. Reoperation was most commonly required because of failure of the aortic valve when a valve-preserving aortic root reconstruction was performed or for other cardiac or aortic disease elsewhere.