Thomas H. Wareing

Sixteen-year Experience With Aortic Root Replacement

During a 16-year interval ending in October 1990, 168 patients underwent 172 aortic root replacements. Thirty patients (18%) had Marfan syndrome. Annuloaortic ectasia (81 patients) and aortic dissection (63 patients) were the principal indications for operation. Twenty-seven patients (16%) had previous operations on the ascending aorta or aortic valve. The hospital mortality rate was 5% and the duration of cardiopulmonary bypass was the only significant independent predictor of early death (p = 0.017). Major modifications in technique were made in 1981, when the inclusion/wrap technique employing a composite graft (used in the first 105 procedures) was abandoned in favor of an open technique (used in 51 procedures), and in 1988, when aortic allografts and pulmonary autografts were introduced for selected conditions (reoperations, dissection, endocarditis, isolated aortic valve disease) in 16 patients. The mean duration of follow-up was 81 months. Forty-six patients were followed for more than 10 years. The actuarial survival rate was 61% at 7 years and 48% at 12 years. No significant difference in survival rate was observed between the patients with annuloaortic ectasia and aortic dissection, or between the inclusion/wrap and open techniques. However the frequency of pseudoaneurysm formation at suture lines and the frequency of reoperations on the ascending aorta and aortic valve were less with the open technique. The actuarial freedom from thromboembolism for the 152 patients with prosthetic valves was 82% at 12 years. One early and one late death occurred among the 16 patients with allograft or autograft root replacement. Anticoagulant therapy was not used in these patients and no thromboembolic episodes occurred in the follow-up period (mean, 7 months). The satisfactory results observed with extended follow-up support the continued use of the composite graft technique as the preferred method of treatment for patients with annuloaortic ectasia, persistent aneurysms of the sinuses of Valsalva following previous operations, and for patients with ascending aortic dissection who require aortic valve replacement. The availability of aortic root allografts and the perfection of techniques for safe implantation of the autologous pulmonary root into the aortic position have broadened the indications for aortic root replacement.

Risks of bilateral internal mammary artery bypass grafting

Although use of one internal mammary artery (IMA) for coronary artery bypass grafting does not appear to be associated with increased risk, the results with both IMAs are less certain; the potential for a higher incidence of sternal wound infection as a result of devascularization of the sternum is a major concern. During a 42-month interval ending July 1988, 1,566 patients had coronary artery bypass grafting alone or in combination with other procedures: 633 received only vein grafts, 687 had unilateral IMA grafting, and 246 had bilateral IMA grafting. The IMA patients were younger, were more often male, had better cardiac function, and underwent fewer emergent, urgent, or combined procedures than the patients receiving vein grafts (p less than 0.05). Thirty-day mortality was lower among the IMA patients (unilateral IMA group, 2.8%; bilateral IMA group, 3.7%; and vein graft group, 7.9%; p = 0.001). With the exception of sternal wound problems, occurrence rates for postoperative complications among the IMA patients did not differ significantly from or were lower (p less than 0.05) than those among the patients with vein grafts. Sternal infections occurred with greater frequency among the bilateral IMA patients (6.9%) than among the unilateral IMA (1.9%) or vein graft (1.3%) patients (p = 0.001). By univariate analysis, obesity, diabetes, bilateral IMA grafting, and need for prolonged (greater than 48 hours) mechanical ventilation were associated with a significantly higher incidence of sternal infection (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Strategy for the reduction of stroke incidence in cardiac surgical patients

Atherosclerosis of the ascending aorta (AAA) and severe carotid artery disease are risk factors for stroke in cardiac surgical patients. Twelve hundred of a consecutive series of 1,334 patients 50 years of age or older having a cardiac operation were screened for the presence of AAA by intraoperative ultrasonographic scanning and for the presence of carotid artery occlusive disease (791 of 798 patients > or = 65 years of age and younger symptomatic patients) by carotid duplex scanning. Coronary artery disease was present in 88% of the patients. Patients with moderate or severe AAA (n = 231; 19.3% of the total) were treated by ascending aortic replacement (n = 27) or by modified, less extensive techniques (n = 168) to avoid the atherosclerotic areas. Thirty-three patients had combined carotid endarterectomy and cardiac operation. Thirty-day mortality and stroke rates for the 1,200 patients were 4.0% and 1.6%, respectively. The stroke rate was low (1.1%) among the 969 patients with no or mild AAA. It was zero among 27 patients with moderate or severe AAA who had ascending aortic replacement and among the 33 patients who had carotid endarterectomy. The stroke rates were higher for 111 patients with moderate or severe ascending aortic disease who had only minor interventions (6.3%) and for 16 patients with severe carotid artery disease who did not have carotid endarterectomy (18.7%). Screening for AAA and carotid artery disease and aggressive surgical treatment of moderate or severe AAA and severe or symptomatic carotid artery disease appears to reduce the frequency of stroke in older cardiac surgical patients.

Atherosclerosis of the ascending aorta. Prevalence and role as an independent predictor of cerebrovascular events in cardiac patients.

The cause of cerebral and peripheral embolism remains undetermined in a significant number of patients. An atherosclerotic thoracic aorta has thus far been considered to be an uncommon one. Methods To define the potential role of the ascending thoracic aorta as an embolic source, intraoperative ultrasonic aortic imaging was performed in 1200 of 1334 consecutive patients aged 50 years and older who were undergoing cardiac surgery. Patients were divided into two groups according to the results of the ultrasound study in terms of presence or absence of atherosclerotic disease. The prevalence of previous neurological events in the two groups was characterized and compared. Results Ascending aortic atherosclerosis was present in 231 (19.3%) of the patients studied. Patients in this category were older (P<.0001). A higher percentage of them were smokers (P<.0001) compared with patients with less severe disease. Coronary artery disease was more extensive (P=.012), and a higher percentage of these patients had a history of peripheral vascular disease (P<.0001). Univariate analysis of the subjects with (n=158) and without (n=1042) previous neurological events indicated that age, body mass index, atrial fibrillation, hypertension, and atherosclerosis of the ascending aorta were associated significantly with previous occurrence of a cerebrovascular accident. For the group as a whole, multiple logistic regression analysis demonstrated that hypertension (odds ratio, 1.81; P=.002), atherosclerosis of the ascending aorta (odds ratio, 1.65; P=.013), and atrial fibrillation (odds ratio, 1.54; P=.060) were significantly and independently associated with the occurrence of previous neurological events. Conclusions Atherosclerosis of the ascending aorta is an independent risk factor for cerebrovascular events. An atherosclerotic ascending aorta may represent a potential source of emboli or may be a marker of generalized atherosclerosis.

Renal dysfunction and intravascular coagulation with aprotinin and hypothermic circulatory arrest

High-dose aprotinin was used in 20 patients undergoing primary or repeat operations on the thoracic or thoracoabdominal aorta using cardiopulmonary bypass and hypothermic circulatory arrest. The activated clotting times immediately before the establishment of hypothermic circulatory arrest exceeded 700 seconds in all but 1 patient. Three patients (15%) required reoperation for bleeding. Seven patients died during hospitalization, and 5 had postmortem examination. Platelet-fibrin thrombi were present in multiple organs including the coronary arteries of 4 patients with myocardial infarction or failure, the pulmonary arteries of 2 patients, 1 of whom died of acute right ventricular failure, the brains of 2 patients who sustained a stroke, and the kidneys of 4 patients, 3 of whom had development of renal dysfunction. Renal dysfunction occurred in 13 patients (65%), and all were 65 years of age or older. Five of these patients required hemodialysis. Among 20 age-matched patients who had similar operations without aprotinin, there was one hospital death (5%) from myocardial infarction, and renal dysfunction developed in 1 patient (5%), who did not require dialysis. None of these 20 patients required reoperation for bleeding. Although aprotinin has been shown to reduce blood loss in patients having cardiac operations employing cardiopulmonary bypass, this benefit was not attained in this group of patients with thoracic aortic disease in whom hypothermic circulatory arrest was used. Use of aprotinin in elderly patients undergoing these procedures was associated with an increased risk of renal dysfunction and failure, and of myocardial infarction and death.

Preoperative carotid artery screening in elderly patients undergoing cardiac surgery

The role of preoperative screening for carotid artery disease in elderly patients undergoing cardiac surgical procedures is not clearly established. This prospective study was designed to determine the prevalence of carotid disease in this population and to identify preoperative risk factors for carotid artery stenosis. During a 54-month interval, 1087 patients of a consecutive series of 1184 patients 65 years of age and older who underwent cardiac surgical procedures (91% had coronary artery disease) were evaluated before operation with carotid duplex ultrasonography. The prevalence of disease was 17.0% for 50% or greater stenosis and 5.9% for 80% or greater stenosis. With use of a stepwise, logistic regression model of 12 preoperative variables, five variables were found by multivariate analysis to be significant (p less than or equal to 0.05) predictors of 80% or greater stenosis: female sex, peripheral vascular disease, history of transient ischemic attack or stroke, smoking history, and left main coronary artery disease. If all patients with at least one risk factor were screened, then this model predicts that 95% of patients with 80% or greater stenosis and 91% of patients with 50% or greater stenosis would be identified before operation. The probability of carotid disease in a given patient can also be estimated (range, 5% to 65%). Carotid endarterectomy combined with cardiac surgical procedures was performed on 46 patients who were either symptomatic (16) or had 80% or greater stenosis (30). The overall stroke rate for the 1087 patients was 2.0% (22 patients), and the 30-day mortality rate was 5.2% (56 patients).(ABSTRACT TRUNCATED AT 250 WORDS)

Intraaortic balloon counterpulsation: Patterns of usage and outcome in cardiac surgery patients

Between January 1, 1986, and May 6, 1991, 7,884 cardiac surgical procedures requiring cardiopulmonary bypass were performed at our institution, including 672 (9.8% of adult procedures) performed in 669 patients that were associated with preoperative (n = 240), intraoperative (n = 353), or postoperative (n = 79) use of an intraaortic balloon pump. The mean age of recipients was 65.3 years (range, 16 to 89 years). Intraaortic balloon pump usage increased during the study period from 6.4% of patients (83/1,298) in 1986 to 12.7% of patients (169/1,333) in 1990. The relative distribution between preoperative (mean, 35.7%), intraoperative (52.5%), and postoperative (11.8%) insertion remained nearly constant during the study period. The overall operative (30-day) mortality for patients with preoperative, intraoperative, or postoperative insertion of the intraaortic balloon pump was 19.6%, 32.3%, and 40.5%, respectively (X2 = 16.4; p less than 0.001). Although use of the intraaortic balloon pump in the intraoperative and postoperative settings is accompanied by a favorable outcome in most patients, the high associated mortality suggests the need for earlier use of the intraaortic balloon pump or other supportive measures such as the ventricular assist device.

Management of the Severely Atherosclerotic Aorta During Cardiac Operations

Embolization of atheroma from the ascending aorta is a major cause of stroke following cardiac surgery. We evaluated a protocol for intraoperative detection and treatment of the severely atherosclerotic ascending aorta which Included eplaortlc ultrasonographic scanning and resection and graft replacement of the involved segment using hypothermlc Ischemic arrest. During an 81‐month interval, 47 patients 50 years of age and older (mean age 71 years) who underwent coronary artery bypass grafting had resection and graft replacement of the ascending aorta. This represented approximately 2% of the patients in this age group who had cardiac operations during this interval. Nineteen patients (40%) required additional procedures. The 30‐day mortality rate was 4.3% (2 patients). Both patients died of myocardial failure. None of the 45 surviving patients sustained a perioperative stroke. There have been no strokes or transient Ischemic events in the follow‐up period, which extends to 72 months (mean 21 months). While this technique for management of the severely atherosclerotic aorta could be considered radical, it was associated with lower mortality and stroke rates than those that were observed in patients with moderate or severe atherosclerosis In whom only minor modifications in technique were made to avoid embolization of atheroma. Resection and graft replacement during a period of hypothermic circulatory arrest is currently our preferred method of treatment for the severely atherosclerotic aorta durlng cardiac surgery. (J Card Surg 1994;9:490–494)

Hypothermic circulatory arrest for cerebral protection during combined carotid and cardiac surgery in patients with bilateral carotid artery disease.

ObjectiveThe authors evaluated the protective effect of hypothermic circulatory arrest for patients with bilateral carotid artery disease who underwent cardiac surgical procedures. Summary Background DataSevere bilateral carotid artery disease coexisting with cardiac disease that requires surgical treatment is associated with a substantial incidence of stroke after operations that require cardiopulmonary bypass. The optimal method of management of patients with these coexisting conditions is not established clearly. Because hypothermia has a protective effect on neural and myocardial tissue during cardiac operations, a protocol employing profound hypothermia and a period of circulatory arrest was evaluated in a group of patients who underwent combined carotid and cardiac surgery who were considered to be at increased risk for the development of stroke. MethodsFifty patients with bilateral carotid artery disease, including 24 patients with high-grade unilateral stenosis and contralateral occlusion and 6 patients with 80% to 99% bilateral stenosis, underwent combined carotid endarterectomy and cardiac surgery (coronary artery bypass grafting in all 50 patients and additional procedures in 8 patients). Profound systemic hypothermia (15 C) was instituted, and the carotid endarterectomy was performed during a period of circulatory arrest that averaged 30 minutes. The cardiac procedure was performed during the periods of cooling and rewarming. ResultsThe 30-day mortality rate was 6% (3 patients). There were no early postoperative strokes or reversible ischemic neurologic deficits. There have been seven late deaths in the postoperative period, which extends to 54 months. None of these deaths were caused by stroke. There has been one late stroke, which occurred in the distribution of the unoperated carotid artery.

Postcardiotomy mechanical circulatory support in the elderly

The role of mechanical circulatory support after cardiac operations in elderly patients is not clearly established. Between November 1985 and July 1989, 18 patients 65 years of age or older (mean age, 71 years; range, 65 to 82 years) were treated after cardiotomy with a centrifugal vortex or pneumatic mechanical ventricular assist device. This group comprised 1.9% of the 926 patients 65 years of age or older undergoing cardiac surgical procedures and 69% of the 26 patients requiring postcardiotomy support during this interval. Before institution of mechanical support, all patients were receiving maximal inotropic support and 16 patients had intraaortic balloon pumps inserted. Univentricular support was used in 9 patients (6 left, 3 right) and biventricular support in 9 patients. The mean duration of support was 45 hours (range, 8 to 118 hours). Twelve patients (67%) were successfully weaned, 8 (44%) were discharged from the hospital, and 6 (33%) remain alive 11 to 31 months postoperatively. Four of the 6 survivors are in New York Heart Association class I, 1 is in class II, and 1 is in class IV. The Combined Registry for ventricular assist device support has recently reported an overall survival rate of 12% in patients 65 to 70 years of age and 6% in those older than 70 years. Our results are comparable with those reported for younger patients and justify the use of postcardiotomy ventricular assist device support in the elderly.