Biomedical subjects

M M Levinson

Publications and source records attributed to M M Levinson.

5 recordsLinked to original sources

PubMed1987

Technical aspects of total artificial heart implantation for temporary applications.

Temporary use of the Jarvik-7 artificial heart in critically ill patients awaiting transplantation has prevented death in greater than 60% of attempts. Success is very dependent on meticulous surgical technique. Failures in the operating room cascade into enlarging problems postoperatively. Appropriately selected patients implanted without bleeding or fit problems recover quickly and are suitable candidates for transplantation within a few days. Even acute renal failure or pulmonary insufficiency from end-stage cardiac disease rapidly reverses upon restoration of normal hemodynamics. Anticoagulation is mandatory to prevent thromboembolism and continuous heparin plus oral dipyridamole is the most successful regimen to date. Primary intraoperative security of all suture lines or potential bleeding foci is thus essential. Bleeding has been associated with tamponade, pulmonary complications, and transfusion stimulated anti-HLA antibodies which can prevent subsequent transplantation. The length and suturing technique of the aortic conduit are critical. Compression of the mediastinal structures by the device can impede systemic or pulmonary venous return, with disastrous results. Displacement of the blood pumps away from the midline, usually into the pleural space, allows for more room when closing the sternum. The 100 cc blood pump fits best in patients greater than 85 kg, while the 70 cc model can be implanted in patients as small as 50-60 kg.

Cardiac Surgical Procedures↗

PubMed1986

Cyclosporine: an immunosuppressive panacea?

Between March 29, 1979, and March 1, 1985, 62 heart transplants were done in 61 patients at the University Medical Center, University of Arizona. There were two treatment groups with nearly equal numbers in each; conventional immunosuppression (1979 to 1982) and cyclosporine (1982 to the present). Comparison of actuarial survival, number of rejection episodes, number of fatal rejection episodes, number of infections, and number of "other complications" failed to reveal any significant difference between the two groups. The cyclosporine-treated patients had a documented increase in blood urea nitrogen and serum creatinine accompanied by an increase in diastolic blood pressure. The length of hospital stay of the cyclosporine group was approximately one half of that of the conventionally treated patients, and they required fewer rehospitalizations. The cost for initial hospitalization was not significantly different between the two groups. Therefore, in 1979 dollars, the cost for cyclosporine-treated patients has decreased. This difference in cost was only minimally diminished by the difference in expenditure for outpatient pharmaceuticals, which was four times higher in the cyclosporine group. We believe that cyclosporine is a potent immunosuppressive agent but that it has toxic, possibly irreversible effects on the kidney. In view of the minimal differences that we were able to demonstrate in survival rejection and infection, it seems prudent to reduce or modify present doses of cyclosporine in an attempt to avoid irreversible renal damage.

Actuarial Analysis↗

PubMed1979

Emergency percutaneous transtracheal ventilation (PTV).

Ventilation through a percutaneous needle catheter inserted into the trachea has been advocated for resuscitation in acute upper airway obstruction. However, the customized, prefabricated equipment proposed by others for that use is not always available. We describe a device for percutaneous transtracheal ventilation (PTV) that can be rapidly assembled using available, inexpensive hospital supplies. With this device, moderate inflation pressures and flow rates of oxygen resulted in arterial PaO2 of greater than 300 torr and PaCO2 values of approximately 40 torr in dogs. PTV may be used as a life-saving measure in cases of acute upper airway obstruction when conventional airway management is unsuccessful.

Airway Obstruction↗

PubMedDate not supplied

Platelet and fibrin metabolism in recipients of the Jarvik 7 total artificial heart.

Recipients of the total artificial heart are at risk for device-related thrombus formation and thromboembolism. Platelet and fibrin metabolism was studied in four patients who received the Jarvik 7 total artificial heart as a bridge to transplantation and in eight patients after orthotopic heart transplantation. Platelet activation was assessed by measurement of plasma levels of beta-thromboglobulin, fibrin formation by fibrinopeptide A, and fibrinolysis by cross-linked fibrin degradation products. These markers were increased after surgery with only minimal differences between the two patient groups for the first 3 days. In comparison to heart transplant patients, these markers remained elevated in artificial heart recipients despite anticoagulation therapy. beta-Thromboglobulin levels did not decrease in two artificial heart recipients who received aspirin. Markers of platelet and fibrin activity were greatly increased in one artificial heart recipient who had impaired inflow into the device, was not anticoagulated because of bleeding, and had extensive device-related thrombus on explantation. Plasma markers of platelet and fibrin metabolism provide biochemical assessment of in vivo thrombus activity in artificial heart recipients. Monitoring these markers may provide an additional means of guiding anticoagulation therapy in patients with artificial hearts and assessing interventions designed to reduce device-related thrombus formation.

Adult↗

PubMedDate not supplied

Three recent cases of the total artificial heart before transplantation.

Three recent cases from one institution using the total artificial heart (TAH) before transplantation are reviewed. The first patient was implanted for 12 hours with the pneumatic Phoenix total artificial heart after failure of a donor heart 1 day after transplant. Following retransplantation the patient died from severe pulmonary edema, pulmonary hypertension, right ventricular failure, and Pseudomonas septicemia. The second patient was implanted with the Jarvik-7 total artificial heart for rapidly deteriorating idiopathic cardiomyopathy. Major complications during the 9 1/2-day implant consisted of severe pulmonary edema for the first 4 days and a multifocal cerebral embolic event on the seventh day after implantation from which he fully recovered. Major problems after transplant included disseminated toxoplasmosis and two mild episodes of rejection. The patient was discharged 68 days after surgery and remains well. The third patient was a 40-year-old woman with rapidly progressing acute influenza A viral myocarditis. Despite immunosuppressive and antiviral therapy, cardiogenic shock with multiple organ failure developed. The 70 ml Jarvik-7 was implanted for 4 1/2 days. Acute humoral rejection from autoantibodies and alloantibodies led to a cardiac arrest on the second day after transplantation. A second 70 ml Jarvik-7 implant was followed by severe multisystem and infectious complications. After prolonged intensive care support, the patient recovered and is now awaiting transplantation. Nearly 100% cytotoxic antibody reactivity caused by multiple antigenic stimuli is preventing ready access to donor hearts for this patient. We view the current role of the total artificial heart as a tool to preserve life until a suitable donor heart can be found, reverse the end-organ effects of progressive heart failure and low output, and restore transplant candidacy in selected patients with temporary reversible contraindications to transplantation.

Adult↗