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Percutaneous transluminal coronary angioplasty (PTCA) of stenotic saphenous vein grafts is less invasive than repeat coronary bypass grafting; however, this procedure is complicated by atheromatous embolization in 2.5%-3.0% of cases, an incidence significantly higher than in angioplasty of native coronary vessels. We reviewed the cases of 98 patients who underwent elective saphenous vein graft angioplasty at our institution. Five patients (5.1%) had non-Q-wave myocardial infarctions after the procedure, documented by elevated serum creatine kinase. In four, atheroembolism was suspected during the procedure. Two patients died, and autopsy showed that both had multiple atherosclerotic emboli to the distal epicardial coronary artery supplied by the vein graft. In addition, multiple infarcts of varying age, some clearly antedating the angioplasty procedure, were identified. These findings suggest that both ongoing, recurrent atheroembolism as well as angioplasty-related embolism may occur in older vein grafts.

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An abdominal left ventricular assist device (ALVAD) is undergoing controlled clinical trials in our institution. The ALVAD is pneumatically-actuated, synchronously or asynchronously with an external console and is interposed between the apex of the left ventricle and the infrarenal abdominal aorta. It is an order of magnitude more effective than conventional intraaortic balloon pumping. Thus far, we have implanted this pump in 21 patients (15 males and six females). The average age has been 50. The duration of cardiopulmonary bypass with intensive pharmacologic support and IABP until ALVAD implantation has been nearly 4 hours. The plasma hemoglobins prior to ALVAD implantation have averaged 168 mg%. The platelet counts at implantation have averaged 68,000 mm(3). The average duration of ALVAD support has been in excess of one day and the longest trial extended for one week. We have been able to remove the pump after ventricular recovery in two instances and effected cardiac allografting in one instance of ALVAD dependency. We have found that (1) the profoundly depressed left (and right) ventricles can recover if totally supported with this device; (2) the device can function in the presence of ventricular fibrillation and/or standstill; (3) the device can effectively replace both left and right ventricular function in the presence of normal pulmonary vascular resistance and microcirculatory hemodynamics; and (4) in the presence of impending multiple organ failure, procrastination in use is to be avoided.

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Intra-aortic balloon pumping to support the failing circulation is now an accepted therapeutic modality. The device is simple. Insertion can be accomplished rapidly and efficiently in emergency rooms, coronary care units, cardiac catheterization suites and operating rooms, preoperatively, intraoperatively and postoperatively. The hemodynamic effects are immediate and predictable, and the accruing clinical results show increasing survival and hospital discharge rates. In these institutions, mechanical support of the circulation by this and more advanced methods has been formalized within the responsibility of a Circulatory Support Service. The purpose of this report is to summarize some observations and analyses which have been made during care of 325 consecutive postcardiotomy and/or postinfarction cardiogenic shock patients. Historical, theoretical, basic, and applied aspects and current results are included. Foremost are the straightforward concepts of considering the heart as a pump, the failing heart as a failing pump and intra-aortic balloon pumping as a temporary intravascular, auxiliary pump, capable of stabilizing or reversing that failure if utilized early in its evolution.

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Ex vivo molecular, microscopic (cellular), microstructural and mechanical methods have been utilized to evaluate biologic, blood-interfacing linings (pseudoneointimal) formed on textured, fibril-flocked pumping surfaces within abdominal left ventricular assist devices (ALVADs) on partial artificial hearts. Thus far, seventeen human and twenty bovine pseudoneointimal linings (1--28 day pumping durations) have been evaluated by these methods. The results indicate that pseudoneointima begins developing within 24 hours after contact of the pumping surface with blood and is well developed at five days. The linings exhibit surface immunofluorescent fibrinogen activity, viable surface macrophages and histiocytes and scattered erythrocytes at ALVAD removal. Structurally similar linings (20 micrometer to 500 micrometer in thickness) develop in calves and in man. Mechanically, pseudoneointima is a stable, adherent, highly compliant, isotropic structural material. It is linearly elastic and strain-rate independent, with small viscous energy losses under physiologic strains. The methods employed for the evaluation of pseudoneointima provide useful information to determine the suitability of textured or rough surfaces for blood interfacing. The cumulative results indicate that the textured surface approach is useful for intermediate-term clinical ALVAD utilization.

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To define more clearly a salvageable patient for possible utilization of a left ventricular assist device prior to multiple organ failure and irretrievability during postcardiotomy intra-aortic balloon pumping (IABP), we made prospective and retrospective analyses to determine prognostic indices for survival. Serial left ventricular function curves (IABP on-off), scoring methods, hemodynamic and renal function tracking trajectories, survival versus nonsurvival data envelopes, and classification methods were developed and used. All patients requiring postcardiotomy IABP support who were in Class A survived; 80 percent of the patients in Class B survived. All patients who remained in Class C for 12 hours or more following operation with IABP support died. These preliminary analyses suggest that the postcardiotomy IABP-supported patient with a score of less than 6 who remains in Class C for 12 hours or more is at the highest possible risk and is a probably candidate for more effective support with a left ventricular assist device.

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The attachment of a prosthesis directly to the part of the skeleton remaining after an amputation offers many improvements over coupling schemes used in conventional prostheses. However, the stresses induced in the bone by the macrostructure of the attached prosthetic device must first be understood because they are a significant consideration in the design of a successful direct skeletal attachment (DSA) system. This investigation utilizes the finite element method of analysis to structurally model some possible DSA systems. Static stress-response models for an above-the-knee human femoral amputation are formulated to investigate the effect of variations in pylon macrostructure on system performance. The models approximate the initial stages of support following the insertion of a pylon into the medullary cavity of the bone and are also used to assess the bond strengths that must be developed between the bone and pylon for a "no-slip" condition to hold at their interface. The analyses indicate that either a shaped, marrow cavity-fit pylon or four 135 degree wedges with a complementary pylon are favorable geometries for a DSA system. The stress levels caused by these two geometries are on the order of 20% of the axial compressive strength of cortical bone. For each, local stress levels at the bone-biomaterial interface remain the critical parameters for investigation.

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