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Biomedical subjects

T Akutsu

Publications and source records attributed to T Akutsu.

At least 127 records · Page 7Linked to original sources
PubMed1976

Mean systemic pressure and mean pulmonary pressure: their effects on the total artificial heart.

Mean systemic pressure (MSP) and mean pulmonary pressure (MPF), which are mean driving pressures for venous return in the natural heart, were studied in 11 calves in which the natural heart had been replaced with a total artificial heart (TAH). They were measured simply by stopping the artificial heart pumping. Although blood translocation from the arterial to the venous side was not performed, the eventual right and left atrial pressures reached six to eight seconds after stopping the TAH would represent MSP and MPP with reasonable accuracy. The MSP varied from nine to 3k mmHg (20+/-6 mmHg), whereas the MPP varied from nine to 39 mmHg (22+/-7 mmHg). The MSP varied in close relation to the right atrial pressure prior to cessation of the TAH (r=0.9124). Increases in RAP and MSP were mainly attributed to an increase in circulating blood volume. In the performance of the TAH, MSP (or MPP), proper diastolic duration and vacuum application during diastole was of prime importance in determining the end-diastolic ventricular volume.

Animals↗
PubMed1975

One 25 day survivor with total artificial heart.

One calf, which weighed 87 kilograms, survived for 25 days with a total artificial heart (TAH) implanted orthotopically. All hemodynamic parameters stayed normal except the right atrial pressure (RAP), which increased gradually toward the end of the experiment. The cardiac output was maintained between 8.0 and 11.0 L. per minute. Kidney function was well maintained, and no pulmonary insufficiency was noted. Infection became obvious after 2 weeks of pumping although it was controlled to the extent that the calf was able to eat, to several factors, amont them mechanical damage to red blood cells, infection, malnutrition, and liver damage. The calf was standing until 30 minutes before its sudden death from cerebral thromboembolism. The calf's activity throughout the postoperative course convinced us of the feasibility of clinical application and of immediate application to studies of cardiovascular physiology and pharmacology.

Animals↗
PubMed1975

Evaluation of cardiac function and venous return curves in awake, unanesthetized cialves with an implanted total artificial heart.

1) The implanted TAH offers a method of evaluating the effects of varying physiologic demands cardiac output and venous return. 2) Cardiac output and venous return measurements offer a method of evaluating system design of the device and driving and control-logic improvements in awake, unanesthetized animals. 3) The obtained cardiac function and venous return curves suggest that the present TAH is less responsive to increases in right atrial pressure than the natural heart, but is still completely controlled by venous return. Therefore, it is extremely important to make every effort to eliminate any factor causing excessive venous return.

Animals↗
PubMed1975

Refinement in application of total artificial heart, with improvement in survival and histopathological findings.

Recent improvements in total artificial heart (TAH) experiments have changed the pathological findings as well as the concept of the TAH. In the past 3 years, 67 experiments were performed in our laboratory. This study concerns the 11 calves operated upon most recently. Histopathological findings in the lungs, kidneys, livers and spleens of these animals were greatly improved over findings from previously studied animals. Disseminated intravascular coagulation (DIC) syndrome has been seen in only 1 calf. These improvements can be attributed to the following factors: (1) Improved management of the lumg during surgery has essentially eliminated pulmonary insufficiency;(2) liver damage has been successfully prevented by the discovery of the relationship between high right atrial pressure and anemia; (3) careful aseptic surgical procedures and optimal prophylactic use of antibiotics and anticoagulants have minimized the incidence of infection and clot formation.

Animals↗
PubMed1972

Morphologic alterations in sheep after implantation of the Akutsu total artificial heart.

The present report describes morphologic alterations produced in sheep after implantation of a four-chambered total artificial heart. Two groups of sheep were studied. The first group was given no special antishock therapy and had an average survival time of 25.8 hours. Major morphologic changes produced in the first group were focal infarction and massive hemorrhage of the large and small bowel, ascites, severely altered lungs and multiple infarcts in the kidneys. The second group of sheep was given antishock therapy and showed an average survival time of 35.4 hours. Severe morphologic alterations in this group were generally absent in all organs except the lungs, which showed varying degrees of congestion, hemorrhage, edema, pneumonitis and atelectasis. Death in both of the above groups was due to development of irreversible hypotension and respiratory failure.

Animals↗