William G. Marshall

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)

Scale and scope economies in the multi-product banking firm

Abstract The multi-product nature of the banking firm is examined utilizing the translog cost function. This analysis indicates that, contrary to conventional wisdom, natural monopoly, scale economies and product-specific decreasing costs are not robust characterizations of the banking industry. There is, however, evidence that the cost function is characterized by economies of scope. The implications of these results are discussed and extensions of this approach suggested.

Increased complications and prolonged hospital stay in elderly cardiac surgical patients with low serum albumin

Cardiac surgery in elderly patients is associated with acceptable operative mortality but an increased complication rate. Malnutrition is common in the elderly and may adversely affect surgical outcome. To determine the effect of hypoalbuminemia on postoperative complications, 92 patients greater than or equal to 75 years (range 75 to 90) undergoing a variety of major cardiac surgical procedures were evaluated. Thirteen patients (14%) had a serum albumin level less than 3.5 g/dl preoperatively. Compared to patients with normal albumin, hypoalbuminemic patients had an increased frequency of postoperative confusion, congestive heart failure, low cardiac output, renal dysfunction and gastrointestinal complications (all p less than 0.05). Mean postoperative length of stay was markedly prolonged in these patients (27 vs 12 days; p less than 0.001), and mortality also tended to be higher (31 vs 13%; p = 0.11). Using multivariate analysis, albumin less than 3.5 g/dl was the most powerful predictor of postoperative renal dysfunction (p less than 0.01), and was also an independent predictor of increased length of stay (p less than 0.01) and gastrointestinal disorders (p less than 0.05). Thus, hypoalbuminemia is a powerful indicator of an increased risk of perioperative complications in elderly patients undergoing cardiac surgery. Increased attention to nutritional factors is warranted in these patients.

Intraoperative Ultrasonic Imaging of the Ascending Aorta

Embolization of atherosclerotic material from the ascending aorta resulting from placement of cannulas or vascular clamps is a major cause of stroke during cardiac surgical procedures. In an effort to identify atherosclerotic disease of the ascending aorta which might predispose to embolization, intraoperative B-mode ultrasonography was performed in 50 patients. The aorta was imaged from the aortic annulus to the origin of the innominate artery in transverse and longitudinal views. The results were compared with visual and tactile examination of the aorta for the presence of atherosclerosis. Ultrasonic imaging demonstrated atherosclerotic disease in 29 patients (58%). Visual examination and palpation identified atherosclerosis in 12 patients (24%). The amount and location of plaque was sufficient to require a change in the site of arterial cannulation or the proximal vein graft anastomoses or the technique of cardiopulmonary perfusion in 12 of the 50 patients (24%). All 12 patients were 65 years of age or older. Palpation underestimates the presence of atherosclerotic disease in the ascending aorta. Intraoperative ultrasonography accurately identifies patients with atherosclerotic disease of the ascending aorta. This allows the surgeon to modify cannulation, perfusion, and operative techniques to reduce the risk of perioperative stroke due to the embolization of atherosclerotic debris from the ascending aorta.

The Coronary-Subclavian Steal Syndrome: Report of a Case and Recommendations for Prevention and Management

The coronary-subclavian steal syndrome involves the siphoning of blood from the myocardium through an internal mammary artery graft because of a proximal subclavian artery stenosis or occlusion, and results in myocardial ischemia. With the increased use of the internal mammary artery for myocardial revascularization, the potential exists for recurrence of angina pectoris in patients who have or in whom develops high-grade stenosis or occlusion of the subclavian artery, because of the coronary-subclavian steal syndrome. The coronary-subclavian steal syndrome can be prevented by the identification of patients with or at risk to develop subclavian artery occlusive disease. All patients undergoing cardiac catheterization prior to coronary artery bypass grafting in which use of the internal mammary artery is anticipated should be evaluated for the presence of upper extremity and cerebrovascular ischemia, the presence of cervical or supraclavicular bruits, and an upper extremity blood pressure differential of 20 mm Hg or greater. Patients with these findings or with evidence of diffuse atherosclerotic vascular disease should have brachiocephalic arteriography at the time of coronary arteriography to identify significant subclavian artery occlusive disease. When this is demonstrated, use of the internal mammary artery as a free graft instead of an in situ graft or use of saphenous vein grafts is indicated. Patients in whom recurrent angina develops following coronary artery bypass grafting that included an internal mammary artery graft should have coronary arteriography to evaluate the presence of coronary-subclavian steal syndrome, and brachiocephalic arteriography. Carotid-subclavian bypass grafting, probably best done with a prosthetic conduit, is the procedure of choice for management of the coronary-subclavian steal syndrome.

Penetrating cardiac trauma.

During a 10 1/2 year interval ending in June 1980, 47 patients with penetrating cardiac trauma were managed at The University of Alabama Medical Center. Thirty-nine patients (83%) were male. Mean age was 31 years (range, 13 to 69). Thirty-two patients (68%) sustained stab wounds (SW) and 15 patients (32%) gunshot wounds (GSW). Forty-two patients (89%) arrived hypotensive (systolic blood pressure less than 90 mm Hg). Twenty-seven patients (57%) had evidence of cardiac tamponade (central venous pressure greater than 15 cm H2O) and 25 of these 27 patients were also in shock. Forty patients (85%) presented with a normal sinus rhythm and seven patients (15%) had an idioventricular rhythm or asystole. Overall mortality was 23% (11 of 47 patients). Forty-three per cent of the patients sustaining GSW (6/14) died compared to 17% (5/33) of the patients with SW (p = 0.04). Mortality for the patients in shock was 26% and for those with cardiac tamponade 15%. Mortality was 16% for the patients with both shock and cardiac tamponade. Thirteen per cent of the patients in normal sinus rhythm died, while 87% of the patients with idioventricular rhythm or asystole died (p less than 0.0001). Mortality in penetrating cardiac trauma remains high, particularly in patients with GSW and in those patients presenting with an idioventricular rhythm or asystole.

Monopoly Power and Expense-Preference Behavior: Theory and Evidence to the Contrary

The expense-preference theory of the firm implies that in noncompetitive product markets, managers hire labor beyond the profit-maximizing level. This theory has recently received empirical support from Edwards (1977) and Hannan and Mavinga (1980). In this article it is shown that for expense-preference behavior to exist, the effectiveness of the technology for conflict control between shareholders and managers must be related to market structure, which is a tenuous proposition. Further, once differences in monitoring costs due to variation in firm size are controlled for, the empirical evidence supports managerial profit-maximizing rather than expense-preference behavior.

Morbidity and Mortality of Coronary Bypass Surgery in Patients 75 Years of Age or Older

To determine factors associated with an increased risk of postoperative complications in elderly patients, 60 consecutive patients 75 years of age or older undergoing isolated coronary artery bypass grafting (CABG) were evaluated. Thirty-nine patients (65.0%) had at least one major postoperative complication, including 2 deaths (3.3%). Low body weight was the only univariate predictor (p less than 0.05) of an increased likelihood of complications overall. Prior cardiac operation, low serum cholesterol value, and prolonged cardiopulmonary bypass time were associated with increased bleeding. Electrocardiographic evidence of left ventricular hypertrophy was associated with prolonged postoperative confusion. Age of 80 years or more and increased cross-clamp time were predictive of pulmonary dysfunction. Low cardiac output occurred more frequently in patients with nonsinus rhythm, prior cardiac operation, recent congestive heart failure, or elevated level of blood urea nitrogen. Identification of risk factors for specific complications should prompt further studies to define ways of reducing morbidity and the resultant high cost associated with CABG in elderly patients.

Toward Further Reducing Wound Infections in Cardiac Operations

BACKGROUND Serious wound infections such as mediastinitis still occur at a rate of 0.8% to 2.0%, according to the most recently published cardiac operative series. METHODS Data from careful surveillance for infection have been collected prospectively during a 4.5-year period on 1,717 patients who underwent cardiac operations performed under direct ultraviolet C radiation. RESULTS The rate for mediastinitis was 0.23%, and for deep incisional infection without mediastinitis, 0.12%; these rates are significantly lower than those for eight of nine of the most recently published cardiac series. When our infection rates were stratified using the National Nosocomial Infection Surveillance risk index, they were also significantly lower in the most important risk categories than the corresponding stratified rates collected from the participating hospitals of the Centers for Disease Control and Prevention National Nosocomial Infection Surveillance system. CONCLUSIONS Though we lack the proof that only a large, randomized study might provide, certainly, one possible explanation for our lower wound infection rate was the use of bactericidal ultraviolet C radiation during operation. This is a simple and effective means of minimizing operating room airborne bacteria as one possible source of these infections.

Circulatory support with a centrifugal pump as a bridge to cardiac transplantation

Since January 1985, the Heart Transplant Program at Washington University Medical Center, St. Louis, has performed 89 heart transplantations in 86 patients. Twenty patients (23%) have required preoperative mechanical support of circulation or respiration prior to transplantation. The Bio-Medicus centrifugal pump (Bio-Pump) formed the basis of our circulatory support system during the period of this report. Nine patients were placed on the Bio-Pump with the intention of bridging them to transplantation. Six patients required left ventricular assistance; in 2, the device was inserted because they could not be weaned from cardiopulmonary bypass. Two patients required biventricular assistance, 1 because she could not be weaned from cardiopulmonary bypass at the end of a cardiac operation. Extracorporeal membrane oxygenation was necessary in 1 patient for right ventricular decompensation and cardiac arrest four hours after orthotopic cardiac transplantation. One of these 9 patients died on circulatory support, and in another, a complication developed that precluded transplantation. The remaining 7 patients (78%) underwent a successful transplant procedure after an average of 1.6 days of circulatory support (range, 0.5 to three days), and all are long-term survivors of transplantation. There has been 1 late death at 17 months from a cerebrovascular hemorrhage. In summary, the centrifugal pump provides excellent short-term circulatory support for individuals who would otherwise die before cardiac transplantation.