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Biomedical subjects

J Kolff

Publications and source records attributed to J Kolff.

At least 55 records · Page 3Linked to original sources
PubMed1975

Silastic T tube splints for biliary repair.

Silastic rubber T tubes have been compared with latex rubber T tubes in the biliary system of dogs. It was found that Silastic rubber T tubes evoked a significant foreign body reaction within the biliary system, producing bile salt precipitation and debris. Alarmingly, in these studies in dogs, Silastic rubber T tubes did not cause sufficient intraperitoneal adhesions around the tube to form an intraperitoneal tract walling off the tube from the general peritoneal cavity. Thus, when the Silastic rubber T tube was removed, bile leakage into the peritoneal cavity occurred. Based on studies in dogs, Silastic rubber T tubes should not be used in the clinical situation in which the T tube would be removed postoperatively.

Animals↗
PubMed1975

Thrombus generation within the artificial heart.

The sites of thrombus formation in the Jarvik III artificial heart were studied in 20 consecutive calf experiments. Identical design and implantation procedures were used with two different surfaces. The 10 anticoagulated calves receiving Dacron-fibrilized silicone rubber surfaces survived an average of 296 hours. In contrast, the 10 nonanticoagulated calves with smooth poyurethane hearts survived 545 hours. The polyurethane surfaces were constantly clean. However, the rough surfaces were coated with variable amounts of thrombi. The sharp angle between the diaphragm and housing contained varying amounts of thrombi deposits in 75 per cent of the cases. Thrombe deposition occurred on 41 per cent of the valves. These thrombe were the source of emboli into the kidney, brain, and lungs. Turbulences and stagnation areas generated thrombus formation. Anticoagulation did not prevent thrombus formation. It would appear that heart free of turbulence and stagnation areas must be designed to eliminate thromboembolism.

Animals↗
PubMedDate not supplied

New polyurethane valves in new soft artificial hearts.

This article describes new bistable valves, and introduces a new soft heart that is easy to implant. Earlier, five polyurethane (PU) valves were implanted in the mitral position in sheep. All five survived for 1 year or more, and the valves, although calcified, were intact. Since the opening resistance was somewhat high, valves that are bistable were developed, which means they may be open or closed. These valves have lower opening resistance, and regurgitation is similar to that of mechanical valves. Eight calves have been implanted with a new, soft total artificial heart (TAH). Seven had bistable leaflet valves; the eighth had mechanical (Bicer) valves in the inflow position. Four of the calves were sacrificed after 22 to 43 days. At autopsy, the number of thromboemboli found, particularly in the kidneys, was low compared with previous experiments. None of these animals received anticoagulants other than the heparin given during heart/lung bypass.

Animals↗
PubMedDate not supplied

Results of the unidirectional Centri-Safe arterial valve for prevention of retrograde flow during cardiopulmonary bypass.

Retrograde blood from the aortic cannula into the cardiopulmonary circuit may lead to aortic air emboli when nonocclusive centrifugal pumps are used. The authors tested a nonregurgitant, unidirectional valve containing a Teflon ball occluder to prevent backflow. In vitro measurements of leakage rate, forward flow pressure drop, burst strength, and hemolysis levels along with animal (n = 12) and human (n = 12) in vivo hematologic and hemolysis levels were measured. Data were analyzed by paired and unpaired Student's t-test. Pressure drop differences at flows of 5 l/min were 7.3 +/- 0.3 mmHg before and 7.6 +/- 0.1 mmHg after 10,800 cycles of pulsatile pumping. (P = NS). Leakage rate during this period at pressures of 100 mmHg was not significant. Volume required to close the Teflon ball was less than 1 ml. Hemolysis analysis done in vitro and in vivo in control (no valve) and experimental (valve) groups used hemoglobin, hematocrit, platelets, plasma free hemoglobin, and lactic dehydrogenase as hemolysis indices. There were no statistical differences. The authors conclude that the CentriSafe valve (Cardiac Systems, Inc., Conshohocken, PA) is safe and prevents fatal backflow and air emboli. The valve is nonthrombotic in anticoagulated blood, can be opened and closed thousands of times, and has a burst strength equal to or greater than other components in the perfusion setup.

Animals↗
PubMedDate not supplied

Successful heart transplantation in recipients with recent preoperative pulmonary emboli.

Acute pulmonary embolus (less than 6 weeks old) has been considered an absolute contraindication to heart transplantation for fear of the potential problems of lung abscess, empyema, bronchopleural fistula, and systemic sepsis in an immunosuppressed patient. It is difficult to adhere to this principle because 30% to 50% of patients with dilated cardiomyopathy may have an acute pulmonary embolus and would be excluded from transplantation. Several centers have considered such patients for heart transplantation if they are young, on maximal medical therapy, and in extremis. The surgical management of the postoperative pulmonary problems can include bronchoscopy, antibiotics, surgical drainage, decortication, and pulmonary resection with or without muscle flaps. We describe our approach to two such patients who were managed successfully with lobectomies and latissimus dorsi muscle flaps to seal the bronchus and fill the pleural space.

Adult↗
PubMedDate not supplied

Deposition of blood elements on vacuum-formed ventricles in calves. A gross and electron microscopic study.

The thrombogenicity of the Philadelphia Heart System was evaluated by implanting left and right ventricles in calves for periods ranging from 1.5 hours to 128 days. Explanted hearts were examined grossly and by scanning and transmission electron microscopy for accumulation of thrombus and ingrowth of pseudoneointima. Visible material was essentially limited to inflow and outflow valves, atrial cuff, and a circumferential band of white thrombus around the junction of the blood diaphragm with the housing. The band was barely visible at 33 days, but was 1 to 3 mm wide at 128 days. SEM examination revealed microscopic deposits of blood elements, mostly platelets, that were present between 10 days and 128 days. The deposits were rather uniformly distributed over the blood contacting surface and remained constant over time. At 128 days, the Dacron (Meadox Medical, Oakland, NJ) graft was partly covered by a thin layer of tissue composed of multiple layers of cells separated by collagen. New blood vessels were frequently found, but fibrin-rich thrombus was present in some areas. Thus, this system was capable of minimizing thrombus accumulation and remained stable for 4 months.

Animals↗
PubMedDate not supplied

Antithymocyte gamma globulin, low-dosage cyclosporine, and tapering steroids as an immunosuppressive regimen to avoid early kidney failure in heart transplantation.

Cyclosporine is a powerful immunosuppressive agent that unfortunately has significant renal toxicity. Two risk factors associated with a high incidence of kidney failure in patients receiving cyclosporine have been described in the literature. In an effort to decrease the possibility of renal toxicity with the use of cyclosporine, we use low-dosage cyclosporine, antithymocyte gamma globulin, and tapering dosages of steroids as an immunosuppressive regimen. Twenty-one patients had orthotopic heart transplants from January 1985 to January 1986. Sixteen of 21 patients or 70% had at least one high risk factor for kidney failure. There were no episodes of acute kidney failure, and the blood urea nitrogen and creatinine levels that were recorded over an average of 8.5 months per patient did not increase significantly from preoperative values. Seventeen of 21 or 81% of the patients are alive and functioning fully. The incidence of rejection per patient was 0.9, and there were no biopsy-proven severe rejections. One patient died at 5 months; the autopsy showed generalized moderate rejection. There were 0.24 episodes of infection per patient, with one patient who died from Pneumocystis pneumonia. With this immunosuppression protocol, early postoperative kidney dysfunction was avoided. The incidences of rejection and infection were within acceptable range, and the quality of life in the 17 survivors is excellent.

Acute Kidney Injury↗
PubMedDate not supplied

Pediatric heart transplantation at St. Christopher's Hospital for Children.

Heart transplantation has become the standard of care for patients with end-stage heart failure. The efficacy and therapeutic advantages of transplantation in the pediatric population have not been fully determined. Between March 1985 and September 1986, nine pediatric heart transplantations were performed; the ages ranged from 39 days to 19 years; weight ranged from 2.3 to 100 kg. The underlying disease was acquired cardiomyopathy (four patients); cardiomyopathy caused by congenital mitral valve disease (two patients); unresectable fibroma of the left ventricle in a newborn (one patient); hypoplastic left heart syndrome (one patient); and hypertrophic obstructive cardiomyopathy (one patient). Initial immunosuppression therapy consisted of cyclosporine, prednisone, and antithymocyte globulin. Recently, newer protocols have evolved through experience. Seven patients survived the perioperative period and had follow-up from 1 to 19 months, for a total of 41 transplant months. Rejection occurred at a rate of 1.4 episodes per month in children compared with 0.8 episodes per month in our adult patients. There was no statistical difference in the number, severity, or timing of rejection episodes in the pediatric versus adult population. Major complications included cyclosporine-induced seizures in two patients, mild hypertension in two, five infectious episodes (three bacterial and two viral), and three late deaths. All children who survived are in New York Heart Association functional class I with no developmental delays. This series is heavily weighted with children (33% less than age 1 year). Early results demonstrate that pediatric and infant heart transplantation is technically practical. Improved results are to be expected with additional experience and further modification of adult protocols to assure patient growth and minimize the high infection rate.

Adolescent↗
PubMedDate not supplied

The role of cardiac valves in artificial heart performance.

The criteria for the design, selection of materials, and fabrication of a total artificial heart have evolved over several years. As these criteria have become more sophisticated and exact, they have optimized the performance of all components within the system. A pump with sufficient volume and pressure output that fits in the available anatomic space was a primary objective. Concomitantly, a nonthrombogenic, durable material that was nondegradable in body fluids was being developed. The most easily managed energy source selected to date has been pulsed, compressed air programmed for gentle but effective systole and diastole. The evolution of good cardiac valves has been of major importance to the artificial heart effort. The historical development of the artificial heart has often centered around existing prosthetic valves which are currently an integral component of the complete system. A detailed analysis of the performance of the total artificial heart clearly identifies the role of the cardiac valve.

Animals↗