Prolonged pulseless perfusion in unanesthetized calves.

Nonpulsatile left ventricular (LV) bypass was achieved in nine alert, active calves for periods of up to two weeks using a centrifugal blood pump. Data were compared to prebypass control values and to results obtained from seven calves that underwent nonthoracotomy, retrograde LV cannulation, and pulsatile bypass for up to 35 days. Nonpulsatile flow produced an increase in heart rate of 20% (P less than .05) and an increase in aortic pressure of 10% (P less than .05). Cardiac output and systemic vascular resistance were similar in both groups for three days; thereafter, vascular resistance decreased as cardiac output progressively increased. Serum renin, lactate, and pyruvate values remained normal; creatinine clearances were not significantly different than control values, and there were no significant changes in body weight. These data indicate no untoward effects as a result of prolonged pulseless perfusion.

Washington State's model of physician leadership in cardiac outcomes reporting.

BACKGROUND: In 1993, the cardiac surgery community in Washington State opposed an effort by the state Health Care Authority (HCA) to identify "centers of excellence" for selective contracting of coronary artery bypass grafting (CABG) procedures, and proposed an alternate model that would create a statewide cardiac outcomes registry under physician governance to be used by all institutions for internal quality improvement activities. METHODS: A prospective pilot data collection effort, which examined preoperative and postoperative patient-reported health status, served as the basis for evaluating the capacity of a physician-led organization to develop a collaborative atmosphere and facilitate universal hospital participation. RESULTS: A surgical steering group met on a regular basis and reached consensus on governance issues, protocols for standardized data collection, and policies regarding data dissemination. All 14 centers that performed bypass surgery in the state participated. Patients who were surveyed reported statistically significant improvements in physical, emotional, and anginal-specific health status after bypass surgery. Baseline patient characteristics and longitudinal outcomes were compared across institutions. CONCLUSIONS: Based on the feasibility of this collaborative outcomes reporting program, the HCA revised its policy regarding selective contracting and has helped to support an ongoing physician-led and -governed cardiac outcomes reporting system that is particularly notable for the subsequent integration of both CABG surgery and catheterization-based procedures into one standardized registry.

Percutaneous transluminal angioplasty. Results and surgical implications.

This retrospective study of 91 percutaneous transluminal angioplasties in 80 patients showed an overall patency rate by life-table analysis of 46 percent with a follow-up period of 36 months. Success rates were significantly reduced by predilatation ankle-brachial ratios less than 0.45, by diabetes, by pain at rest or necrosis, and somewhat, by older age. The overall success rate for iliac dilatation was significantly better (58 percent) than that in the femopopliteal segments (18 percent). Although percutaneous angioplasty was performed on many patients thought to be high surgical risks, the complication rate was low, and complications that required surgical intervention were rare (4 percent). Angioplasty was used as an adjunct to vascular surgery in several ways. An attempt to dilate a Dacron graft-femoral artery anastomosis was unsuccessful, and one of two dilatations distal to a femoropopliteal bypass was successful. However, the combination of an iliac angioplasty with outflow femoropopliteal or femorofemoral bypass produced a long-term patency rate of over 85 percent, significantly better than that achieved with iliac dilatation alone. Percutaneous transluminal angioplasty is both an alternative and an adjunct which should be considered by vascular surgeons for their patients.

Platelet function in calves: a study of adhesion, aggregation, release, clotting factor activity and life span.

Normal calf platelets were found to significantly differ human platelets in a number of important respects. The average calf platelet count is more than twice the average human value. Calf platelets demonstrated no adhesion to glass, in a test in which over 50% of human platelets adhered. Responsiveness to several aggregating, agents, including ADP, thrombin and collagen, was markedly diminished in the calf platelet, requiring much higher concentrations of the stimulating agent to produce comparable responses. In addition, calf platelet clot-promoting activity was far less effective than with human platelets following stimulation with Celite or Russell's viper venom, although the total platelet factor 3 content exceeded that found in human paltelets, following complete disruption. In addition, the calf platelet has a significantly shorter life span and higher turnover rate than the human. These species differences in normal platelet function must be considered in evaluating the results of experiments with artificial organs in the calf model.

Structural correlates of platelet functional damage by physical forces.

Human platelets, which were selectively damaged either in a device designed to impose surface injury or one in which damage is primarily limited to shear forces in the fluid bulk, were examined with the electron microscope in an effort to correlate functional and ultrastructural evidence of injury. Surface injury results in more severe inhibition of platelet adhesion and aggregation, as well as PF-3 and PF-4 activity. These functional effects are accompanied by profound and widespread ultrastructural changes, including membrane defects, enlargement of the open cannicular system, alterations in dense bodies and alpha granules, and the development of globular shapes. Very little serotonin is lost, but there is an increase in the number of abnormal dense bodies. In contrast, the shear injured cells demonstrate few functional defects, despite a lesser but still substantial number of structural changes, at forces up to 10(5) dynes/cm2. At higher shears, both functional and structural evidence of severe injury is present, along with apparently normal platelet aggregation.