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Biomedical subjects

W J Kolff

Publications and source records attributed to W J Kolff.

At least 109 records · Page 6Linked to original sources
PubMed1977

Implantation of the total artificial heart by lateral thoracotomy.

Progress in the techniques for surgical implantation of the artificial heart has progressed in parallel with the technology and design of the prosthesis. In the author's first experience with total artificial heart (TAH) implantation (1968) a trans-sternal split was used opening the sixth intercostal space on the right side across the sternum to the left space. This obviously was not the optimum approach but the complexity, design and size of the prosthesis required maximum exposure of the atria and great vessels. Subsequently the mid-sternal split incision was used. The Dacron fibril coated silicone rubber 8 cm Kwan-Gett ventricles implanted by the mid-sternal split sustained a calf for 14 days in 1972. A calf with the improved Jarvik 3 ventricles fabricated with the same material and implanted via mid-sternal split survived 19 days in early 1973. The surgical techniques for lateral (right) thoracotomy were adopted in this laboratory in 1973. These techniques were applicable only when the prosthesis fit better in the chest. This procedure has been adopted by other laboratories replacing the natural heart of the calf with a TAH. This report describes in detail the stepwise procedure for implantation of the total artificial heart by a lateral thoracotomy in the calf.

Animals↗
PubMed1976

Material and design factors in thromboembolization in total artificial heart recipients living 100-2,000 hours.

When total artificial heart (TAH) recipients live over 100 h it is possible to evaluate the thrombogenicity of design and biomaterials. In 20 consecutive TAH recipients of the Jarvik heart with Björk-Shiley valves we compared rough (Dacron fibril-coated Silastic) and smooth (Biomer and Avcothane) blood surfaces. The mean survival times with rough surfaces was 296 h, with smooth surfaces 545 h. The present designs necessitate a sharp angle junction between the diaphragm and housing, creating stagnation areas and turbulences which induce thromboembolization. The valve rings and struts are another constant source of thromboembolism. Of the 80 valves, 41% showed thrombus deposition independent of anticoagulation. The polyurethane surfaces, in contrast to the fibrilized surfaces, were very clean and free of thrombi at autopsy. The thromboembolization was not dependent on anticoagulation and platelet adhesiveness inhibitor in hearts with rough surfaces. Based on 20 experiments including 78- and 94-day TAH survivors (Avcothane and Biomer hearts), there is an indication of the need of a new ventricular design. The ultimate design should generate physiological pulse waves without turbulences or stagnation areas within the device.

Animals↗
PubMed1976

A three-month survival of a calf with an artificial heart.

An artificial heart constructed from Biomer, a polyurethane, kept a calf alive for more than three months after its natural heart was removed. During this time all of the calf's vital organs apparently functioned well. We had been able to keep similar animals alive with Jarvik III hearts made from Silastic for one month. The principal problem encountered was the infection centering along the compressed air drive lines to the artificial heart. Another problem is thrombus formation in the artificial heart. Redesigning of the artificial ventricles to improve flow patterns and reduce material discontinuities should be attempted to eliminate localized thrombus formation within the ventricles. The rapid growth of the calf has led us to examine the possibility of alternative animal models for future long-term experiments. The most encouraging aspects of this experiment were the long survival time of the calf and the very low level of blood damage caused by the artificial heart.

Alkaline Phosphatase↗
PubMed1976

Transapical left ventricular bypass (TALVB) without an auxiliary ventricle.

A simple transapical left ventricular bypass system employing a roller pump, transapical LV withdrawal catheter, and outflow filter for continuous blood filtration, has been developed and evaluated in unanesthetized sheep for periods beyond 2 wks. The system provides continuous partial LV bypass and is capable of totally maintaining the circulation in the presence of a vasodilator or when total bypass is desired. Blood damage is minimal and blood transfusions have not been required. The transapical withdrawal catheter has been left in the LV apex beyond 4 mos and demonstrates thrombus formation and myocardial histological changes which suggest this catheter should be removed after pumping or long-term anticoagulation provided.

Animals↗
PubMed1976

Saving the aortic and pulmonary artery valves with total heart replacement.

The natural aortic and pulmonary artery valves can be saved with excision of the ventricles and inflow valves. These valves remain functional and unaltered with implantation of an artificial heart, when pumped for 96 and 122 days. The capacity of the artificial heart to meet the physiological needs of the animal, during exercise and body growth, over 3 and 4 mos has been documented. All of the parameters monitored in 2 experiments for 3 mos (and continuing) and 4 mos clearly demonstrates the efficacy of meeting the cardiac needs with an artificial heart.

Animals↗
PubMed1975

Use of artificial heart for basic cardiovascular research.

Improved technology in artificial heart development and implantation studies in unanesthetized calves have stimulated a new model for cardiovascular research. Independent control of the left and right ventricles, replacement of the natural right atrium with an artificial atrium (with a compliant inner diaphragm) are illustrated as examples of new methods to study the cardiovascular system. Preliminary results in three calves suggest that synchronous ventricular pumping is not required for total circulatory maintenance. In four calves a passive artificial right atrium was shown to decrease outflow obstruction to the right ventricle. A compliant inner deiapragm demonstrated a reduction in the amplitude of the atrial C and V waves. The effects of volume and drug infusion on peripheral vascular response in the presence of controlled artificial heart pumping (which does not respond to direct neural or hormonal influences) further illustrate the efficacy of this preparation as a new model for cardiovascular research.

Animals↗
PubMed1975

Comparative evaluation of artificial ventricles in the United States.

A cooperative, comparative evaluation of nine artificial ventricles was performed on two standardized mock circulations. The ventricles included five air-driven diaphragm types, three sack types and a mechanically driven type. The slopes of the ventricular output curves varied from 0.04 to 0.88 at 0 to 5 Torr filling pressure and the maximum ventricular output varied from 3.8 to 11.9 liters/min at 100 Torr outflow pressure. All ventricles had decreased output with increased outflow pressures (70 to 130 Torr). Hemolysis index ratio (HI test/HI std) for HI std equals 0.024 plus or minus .005 (plus or minus 1 SD) g/100 liters (N equals 12), was +21.5 and +6.9 for a Dacron cloth and fibril heart, respectively, +2.0 to +2.86 for three sack ventricles, and +3.2 for a smooth diaphragm ventricle. The mechanical ventricle with a sinusoidal driving waveform and smooth surface had the lowest hemolysis, HI equals 0.008 plus or minus 0.003 (plus or minus 1 SD) (N equals 6). Sack ventricles caused marked hemolysis if the walls touched during systole. Ventricular dimensions varied: weight 116 to 700 g, length 9.2 to 18.7 cm, and volume 235 to 430 ml. Performance data was returned to each individual laboratory which resulted in modification of ventricular design in at least three instances. Comparative, standardized testing of artificial ventricles may shorten development time and provide performance criteria for application in man.

Animals↗