SUMMARY The significant risk of fatal myocardial infarction after carotid endarterectomy in patients with coronary disease long has been recognized. In 1,546 consecutive carotid endarterectomies performed in 1,238 patients over the last 10 years, angina pectoris was present in 17% (212/1,238) of patients; a further 32% (396/1,238) of patients were asymptomatic, but had a history of myocardial infarction. The perioperative mortality (30 day) in the 1306 consecutive endarterectomies in 1,026 patients without symptomatic coronary artery disease was 1.5% (15/1,026 patients). Of the 212 patients with symptoms, 85 carotid endarterectomies were performed in 77 patients without prior coronary bypass operation with an operative mortality of 18.2% (14/77 patients). The remaining 135 patients had 155 carotid endarterectomies but were treated by either prior coronary artery bypass (84 patients) or simultaneous carotid endarterectomy and coronary artery bypass (51 patients) with an operative mortality of 3% (4/135 patients). The greatly unproved survival in those patients with symptomatic coronary disease who had a coronary artery bypass prior to or at the same time as carotid endarterectomy, and the absence of permanent neurological deficit in the 51 of these 135 patients who had simultaneous carotid endarterectomy and coronary artery bypass suggests that significantly improved survival can be achieved after carotid endarterectomy in these high risk patients by the use of simultaneous coronary artery bypass surgery.
Stroke Vol 10, No 2, 1979ISOLATED CAROTID endarterectomy performed in the presence of severe coronary artery occlusive disease has been reported to be associated with an operative mortality of up to 20% and a delayed mortality rate of 25-50% from myocardial infarction.1 " 3 In recent years, since the coronary bypass operation has emerged as an effective therapy, we have been interested to determine whether the application of this technique could alter favorably the recognized high mortality from heart disease associated with carotid reconstruction. This study was undertaken to ascertain the appropriate management of the candidate for carotid reconstruction who also has symptomatic coronary artery disease.
Materials and MethodsThe fate of 1,238 consecutive patients who underwent 1,546 carotid endarterectomies between 1967 and 1977 was reviewed. There were 776 (63%) males and 462 (37%) females. The ages ranged from 32-92 (mean 64 years) with the greatest incidence in the sixth and seventh decades of life. Staged bilateral operations were performed in 308 patients (25%). Associated risk factors for atherosclerosis were common (table 1). Patients with blood pressures greater than 150 mm Hg systolic and 90 mm Hg diastolic were considered hypertensive. A patient was considered obese if he was 20% in excess of his ideal weight. The presence of diabetes mellitus was determined by an abnormal glucose tolerance test or a
A mutant strain of Escherichia coli previously thought to possess low levels of ribonuclease II activity has normal levels of ribonuclease II after partial purification of this enzyme from crude extracts.Recently Wright (9) reported the isolation of mutants of Escherichia coli possessing low levels of ribonuclease I (EC 2.7.7.16), as well as one strain with very low ribonuclease II activity. These strains were isolated by their inability to degrade their deoxyribonucleic acid (DNA) during autolysis in the presence of toluene; since ribonucleic acid inhibits deoxyribonuclease I (4), mutants lacking ribonuclease would be expected not to degrade their DNA. The presumptive deficiency in ribonuclease activity was determined directly by measuring ribonuclease I and II activities in crude extracts.At present, no well characterized strain of E. coli lacks ribonuclease II (Weatherford, Rosen, Gorelic, and Apirion, J. Biol. Chem., in press). Furthermore, a point mutation in another mutant of E. coli results in increased levels of ribonuclease II and in nonviability at elevated temperatures (5, 6). These findings suggest that ribonuclease II may be an indispensable enzyme and, moreover, that the level of enzyme activity is critical. These findings warranted a re-examination of the mutant E. coli MRW12 isolated by Wright (9), especially in view of the recent observation that deoxyoligonucleotides inhibit ribonuclease II activity (2). The results presented here suggest that this mutant contains ribonuclease II; although in agreement with the results of Wright (9), crude extracts appear to contain limited amounts of ribonuclease II activity.Extracts from strain MRW12 and its parental strain HfrH were prepared and examined for ribonuclease II activity. As can be seen in Fig. 1, extracts of strain MRW12 appear to contain lower ribonuclease II activity than extracts from the parental strain HfrH. The techniques used for this measurement
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