Complications associated with surgical procedures generally required for implantation of left ventricular assist devices (LVADs) may limit them from providing adequate circulatory support for patients suffering from profound left ventricular failure (LVF). Such problems are minimized with the use of the Hemopump, a recently developed intraarterial LVAD. This 7 mm transvalvular axial flow blood pump is percutaneously powered by an external console with a flexible drive cable. Since April 1988, we have used the device effectively in 12 patients. Indications for device application included postcardiotomy shock in eight patients, acute allograft rejection in two, severe allograft failure in one, and acute myocardial infarction in one. The Hemopump was inserted from the femoral approach in eight patients, the ascending aorta in three, and the abdominal aorta in one. During the first 12 hr of support, cardiac index (CI) ranged from 1.14-2.98 L/min/m2, and pump flow was 3.0 to 3.6 L/min. As the patients' hearts recovered, the pump speed was gradually reduced. Circulatory support ranged from 26 to 139 hr; 10 of 12 patients were successfully weaned. The mean CI before device removal was 2.74 +/- 0.4 L/min/m2, and the pump flow was 2.14 +/- 0.69 L/min. No device-related infections or thromboembolic episodes occurred. Plasma-free hemoglobin remained within acceptable levels during pumping. Six patients survived more than 30 days after pump removal. Thus, the Hemopump can provide safe, stable, temporary circulatory support and can be expeditiously applied with minimal complications.

Adult↗

PubMedDate not supplied

In vivo evaluation of a trileaflet mechanical heart valve.

Design goals for a mechanical heart valve include duplicating the hemodynamic performance of the natural valve, eliminating the need for anticoagulants, and maintaining safety. The Lapeyre-Dassault (Dassault-Aviation, Paris, France) prosthetic valve, undergoing development, addresses these goals. The unique trileaflet design consists of a solid titanium ring and three leaflets. Prototypes of the valve fabricated with Delrin leaflets were implanted in the mitral position in six calves (70-90 kg). Four calves (Studies 1, 2, 3, 5) had long-term survival of 165, 158, 219, and 281 days, respectively. Two calves were killed, one on Day 37 and one on Day 39, after complications unrelated to the valve developed. In all calves heparin was given intravenously to maintain partial thromboplastin time at 1.5 to 2.0 x baseline for approximately 1 week. In Studies 1 and 2 full anticoagulation and antiplatelet therapy was given (orally administered sodium warfarin to maintain prothrombin time at 1.5 to 2.0 x baseline, along with aspirin (1 g/day) and dipyridamole 400 mg/day). In Study 3, all anticoagulation and antiplatelet therapy was discontinued at 1 month after implant. In Study 5, no anticoagulation therapy was given after the initial week of intravenous heparin; however, antiplatelet therapy was started on the fifth postoperative month and maintained until the study's end at 9 months. At 1, 2, 3, and 5 months, the mean plasma free hemoglobin level in the four long-term animals was 5.0 +/- 2.16, 6.0 +/- 3.83, 8.5 +/- 4.93, and 11.3 +/- 6.74 mg/dl, respectively. Hemolysis was not a problem. Valve performance during normal activity was excellent in all the calves, as evidenced by echocardiography and the overall appearance of good health. In the four completed long-term studies, left heart catheterization showed a mean valve pressure gradient of 11.57 +/- 1.26 mmHg and no apparent valvular regurgitation. Histopathologic examination of major organs showed no evidence of thromboembolic events. This study shows that the innovative design of this trileaflet valve performed well in initial in vivo testing, justifying further development.

Animals↗

PubMedDate not supplied

In vivo evaluation of an intraventricular electric axial flow pump for left ventricular assistance.

In vivo studies have begun to evaluate a new intraventricular electric axial flow left ventricular assist device (LVAD), the Jarvik 2000, which is a small, valveless pump that is placed inside the left ventricle through the left ventricular apex. The operation, which is performed through a left thoracotomy, may be done without cardiopulmonary bypass and aortic cross-clamping. Outflow is provided through a 16 mm softly woven, Dacron graft anastomosed to the descending thoracic or abdominal aorta. Pump flow, which varies from 2 to 16 l/min in vitro, is changed by adjusting the speed of pump rotation. Preliminary studies were done to evaluate the ease of implantation, hematologic and anatomic compatibility, and pump performance. The device has been implanted in seven healthy, preconditioned calves (83-138 kg), one of which is currently undergoing support. The implantation procedure averaged 3 hours. There were no operative deaths, and blood transfusions were not required. Postoperatively, anticoagulation was achieved with heparin followed by warfarin sodium to maintain prothrombin time or partial thromboplastin time at 1.5-2.0 times baseline. In the six completed studies, support time ranged from 2 to 120 days (mean, 36 days). The seventh calf has been supported for 30 days. In the four long-term studies (20, 70, 120, > 30 days), the mean plasma free hemoglobin values during support were 11.0, 7.7, 6.6, and 3.4 mg/dl, respectively. Under normal conditions, the average daily flow rate ranged from 5 to 6 l/min. During treadmill exercise (10% grade, 1.5 km/h) lasting 20 minutes, peak flow rates exceeded 8 l/min. These pilot studies suggest that this intraventricular axial flow pump is relatively easy to implant, operate, and control. In addition, it is hemocompatible, provides physiologic flow rates, and may be able to provide long-term circulatory support.

Animals↗

PubMedDate not supplied

Five month survival in a calf supported with an intraventricular axial flow blood pump.

We are studying in vivo an intraventricular axial flow blood pump (Jarvik 2000) designed for long-term left ventricular support. The small (25 cc, 85 g) valveless pump has been placed intraventricularly in seven calves; pumps have functioned for as long as 5 months. In the four most recent long-term studies completed, calves have survived for 70, 120, 155, and 162 days (in that order); weight gain has averaged 0.56 kg/day. One study is ongoing at more than 30 days. Under resting physiologic conditions in the normal calf, the continuous flow pump produces flows of 5-6 L/min with a decreased arterial pulse contour. The device has caused no physiologic complications. Calves in the completed studies had mean free plasma hemoglobin levels of 11.4, 7.1, 6.5, and 4.3 mg/dl, respectively. We have modified the inflow structures of the device, and these results suggest that a thrombus free design with no pannus at or around the inlet of the pump can be achieved. Histopathologic analyses of the heart and kidneys in studies of as long as 5 months show no deleterious effects of this device. These studies demonstrate the feasibility of a small implanted intraventricular blood pump for long-term use. Future developments for permanent implantation will include implanted physiologic control systems, transcutaneous energy transmission systems, and implanted batteries.

Animals↗

PubMedDate not supplied

Surface texturing and coating of biomaterial implants: effects on tissue integration and fibrosis.

To determine whether texturing and coating have additive effects in promoting tissue integration and inhibiting fibrosis, we evaluated smooth silicone rubber (SSR), textured silicone rubber (TSR), porous silicone rubber (PSR), expanded polytetrafluoroethylene (ePTFE), and porous polyurethane (PPU) subcutaneous implants in eight minipigs. Some of the implants were coated with type IV collagen (Col) and/or fibronectin (Fn). At 6 months, we removed the implants and examined them microscopically. Texturing was more important than Col and Fn in reducing fibrosis and inflammation. The PSR yielded the best response, including reduced fibrosis and inflammation, satisfactory adherence, and no dystrophic mineralization.

Animals↗

PubMedDate not supplied

Treatment of cardiac allograft failure by use of an intraaortic axial flow pump.

Since April 1988 we have used the Hemopump device, a new means of circulatory support, to successfully treat three orthotopic heart transplant recipients with biventricular failure refractory to conventional therapy. The Hemopump device is a 21F catheter-mounted, transvalvular, intraaortic axial flow pump. Power to the pump is percutaneously transmitted from an external electromechanical drive console by a flexible drive cable. We first used the pump in a 61-year-old man in whom severe steroid-resistant rejection developed 28 days after heart transplant, resulting in cardiogenic shock (cardiac index less than 2.0 L/min/m2) despite maximal inotropic support. In the second case a 49-year-old man with no evidence of pulmonary hypertension sustained cardiac arrest 2 hours after heart transplant, necessitating open chest massage and emergency cardiopulmonary bypass. The third patient was a 9-year-old boy in whom rejection developed 5 months after heart transplant, resulting in congestive heart failure that was unresponsive to maximal medical therapy. The device was implanted by way of the femoral artery approach in the first case, the ascending aorta in the second, and the distal abdominal aorta in the third. Duration of support was 46 hours, 65 hours, and 6 days, respectively. Increased blood flow provided by the pump ranged from 2 to 4 L/min. No device-related complications, such as hemolysis, infection, or thromboembolic events, occurred. All patients recovered normal heart function and were weaned from the device. The first patient is well after 12 months. The second patient died of metastatic lymphoma at 2 months, and the third died of Pseudomonas pneumonia after 2 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗

PubMedDate not supplied

Simplified method of hemofiltration in ventricular assist device patients.

Hypervolemia frequently complicates the management of ventricular assist device (VAD) patients as a result of increased intravenous fluid administration and concomitant renal dysfunction. Although acute hemodialysis (AHD) can be used to treat such patients, it requires additional equipment, vascular access cannulations, and personnel. Moreover, hypotension during AHD may occur as a result of rapid shifts in intravascular volume. From January 1987 to March 1988, we treated nine selected VAD patients who had hypervolemia and acute renal failure with a simplified hemofiltration technique. A continuous arteriovenous hemofiltration (CAVH) cartridge was connected from the outflow circuit of a centrifugal blood pump to a large-bore central venous catheter. With CAVH, gradual removal of 272 cc/hour of ultrafiltrate was accomplished for periods up to 241 hours. No episodes of hypotension, thromboembolism, or other deleterious effects occurred. In our series, the CAVH technique was effective in treating hypervolemia in selected VAD patients.

Acute Kidney Injury↗

PubMedDate not supplied

Progress in the development of a transcutaneously powered axial flow blood pump ventricular assist system.

Development of the Jarvik 2000 intraventricular assist system for long-term support is ongoing. The system integrates the Jarvik 2000 axial flow blood pump with a microprocessor based automatic motor controller to provide response to physiologic demands. Nine devices have been evaluated in vivo (six completed, three ongoing) with durations in excess of 26 weeks. Instrumented experiments include implanted transit-time ultrasonic flow probes and dual micromanometer LV/AoP catheters. Treadmill exercise and heart pacing studies are performed to evaluate control system response to increased heart rates. Pharmacologically induced cardiac dysfunction studies are performed in awake and anesthetized calves to demonstrate control response to simulated heart failure conditions. No deleterious effects or events were encountered during any physiologic studies. No hematologic, renal, hepatic, or pulmonary complications have been encountered in any study. Plasma free hemoglobin levels of 7.0 +/- 5.1 mg/dl demonstrate no device related hemolysis throughout the duration of all studies. Pathologic analysis at explant showed no evidence of thromboembolic events. All pump surfaces were free of thrombus except for a minimal ring of fibrin, (approximately 1 mm) on the inflow bearing. Future developments for permanent implantation will include implanted physiologic control systems, implanted batteries, and transcutaneous energy and data transmission systems.

Animals↗