Search PubMed⌕ Search

Biomedical subjects

D B Olsen

Publications and source records attributed to D B Olsen.

At least 145 records · Page 8Linked to original sources
PubMed1980

Reoperative surgery in calves with a total artificial heart.

Two surgical techniques have been developed in our laboratory to deal with identifiable problems in long-term artificial heart experiments. A right throacotomy is used to deal with problems such as extensive bleeding, which occur in the immediate postoperative stage of the experiment, while a left thoracotomy is used in cases in which the original implantation is preceded by more than one week, since extensive adhesions complicate the right thoracotomy at that stage. Pulmonary problems have been eliminated as primary cause of difficulties after reoperation, but infection remains a serious problem.

Animals↗
PubMed1979

The improving hematologic picture in long-term surviving calves with total artificial hearts.

A coagulopathy associated with severe hemolysis was a limiting factor in obtaining long-term survivors among calves with total artificial hearts in 1969. Conversion of design from sac-type hearts to flexible diaphragm hearts, and from Silastic Dacron-fibril intimas to smooth polyurethane intimas, resulted in an abatement of the coagulopathy. In the most recent series of animals studied at this laboratory, platelet counts are normal and platelet survivals are half of normal. Plasma hemoglobins are normal. The coagulation system is still activated at specific loci within the total artificial heart, but is best compensated for in calves treated with antiplatelet drugs, having polyurethane hearts.

Animals↗
PubMed1979

Six-month survival of a calf with an artificial heart.

A pneumatically powered artificial heart, constructed primarily from a polyurethane, was implanted in the chest of a calf and supported the calf for more than 6 months. The heart, which was designed to fit in the chest of a 90 kilogram calf, was able to suppor the animal when it weighed 180 kilograms. During the first 105 days the calf remained strong and healthy. The animal grew progressively weaker after day 106, and by day 160 right heart failure became apparent. The principal cause of the right heart failure was an obstructive growth between the right atrium and the right ventricle. An attempt to correct the problem on day 184 with an artificial heart resulted in the animal's death.

Animals↗
PubMed1978

The role of alveolar recruitment and de-recruitment in pressure-volume hysteresis in lungs.

Gil and Weibel (1972) have demonstrated the importance of alveolar recruitment at relatively low inflating pressures, which has also been noted by Klingele and Staub (1970). These findings are incorporated into a model of alveolar mechanics which presents a possible solution to the questions concerning the classical theory of PV hysteresis which are raised by the mercury filled lung and the Tween 20 rinsed lung experiments. A mathematical model was used to test the hypotheses and curves consistent with the experimental data are generated by a small computer. It is concluded that according to the model, the classical theory of PV hysteresis is valid under normal physiologic conditions but alveolar recruitment and de-recruitment become important factors in alveolar mechanics under conditions of alveolar instability.

Animals↗
PubMed1978

The beat goes on: status of the artificial heart, 1977.

After two decades of continuous research on the artificial heart, survival times of experimental animals indicate that clinical application of such a device is definitely feasible. However, a number of problems remain to be solved. Durability of the device, infection, pannus formation at the interface between the device and natural tissue and thrombosis within the device appear to be the major problems. Development of an implantable power source is also an area of important research. Questions of efficiency, cosmetic and psychological acceptability and cost are just beginning to be considered.

Animals↗
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

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↗