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Biomedical subjects

H Harasaki

Publications and source records attributed to H Harasaki.

At least 91 records · Page 5Linked to original sources
PubMed1981

Hemodynamic regulation in total artificial heart recipients.

The right and left atrial pressures (RAP and LAP), circulating blood volume (CBV) and pump output were analyzed in 17 calves implanted with a free-diaphragm-type total artificial heart. A high RAP and increased CBV were common features in these animals, while the LAP was maintained in a nearly normal range throughout the course. Some correlation was seen between RAP, CBV and pump output, which was maintained in the range of 86.6 to 130.1 ml/min/kg. In the atrial myocardium various morphological changes were observed accompanied by thickening of the cell, which was conspicuous after one month of implantation. To improve this high venous pressure problem, an automatic controller for pusher-plate-type pumps wtih a greater sensitivity was introduced. A preliminary in vivo study using this new system is also reported.

Animals↗
PubMed1980

Chronic nonpulsatile blood flow in an alive, awake animal 34-day survival.

Most acute studies of nonpulsatile blood flow have shown effects on systemic organs. There have been few long-term studies of the effects of nonpulsatile blood flow due to lack of an appropriate experimental model and, consequently, it is unknown whether mammalian physiology can adapt to chronic nonpulsatile blood flow. The following case report documents the effects of chronic nonpulsatile blood flow in an alive, awake animal maintained with fibrillating ventricles for a period of 34 days.

Animals↗
PubMed1980

Bovine aortic and human dura mater valves: a comparative study in artificial hearts in calves.

Thirty-one glutaraldehyde-treated bovine aortic valves (BAVs) and 105 glycerol-treated human dura mater valves (HDVs) were used in 51 various artificial hearts up to 316 days in calves. Multiple valves were implanted in the same animal under different hemodynamic conditions. A comparative study of these valves was performed in terms of blood compatibility and durability with relation to the different hemodynamic environments. Both BAVs and HDVs showed good blood compatibility. The degradation of collagen bundles of the valves began as early as 7 days in BAVs and 13 days in HDVs, and was seen in the hinged portions of the cusps. The fiber separation and resultant void formation were followed with insudation of blood elements and subsequent calcification. Calcification was dystrophic in nature and was encountered in 70.9% of BAVs and 7.6% of HDVs. All 17 BAVs used more than 30 days were calcified; in HDVs the earliest calcified lesion was seen in a 78 day specimen. The pathological changes were more severe in the left side than the right of the total artificial hearts. These results clearly indicated that the HDV is more durable than the glutaraldehyde-treated BAV. It was suggested that degradation of these tissue valves is greatly affected by the degree of hemodynamic stress on the valve cusp. Although glutaraldehyde treatment has increased the durability of tissue valves in general, the structure of the valve tissue also plays an important role in long-term durability.

Animals↗
PubMed1979

The dura mater valve: in vitro characteristics and pathological changes after implantation in calves.

Human dura mater valves of various sizes with rigid and flexible stents were tested in an in vitro pulsatile mock circulatory system. A 22-mm flexible stent valve incorporating a new fabrication technique showed almost the same pressure gradient as a 28-mm rigid stent valve. The backflow/stroke volume ratio was about 4% at a net flow of 10 L/min. One hundred and five rigid stent-mounted dura mater valves were used in 51 pump implantations for up to 316 days. Collagen fiber degeneration began three months after implantation. Microscopic and macroscopic calcification of the valve tissue was seen in eight out of 105 valves, giving an overall incidence of 7.6%. The calcified degeneration was dystrophic in nature, not accompanied by cellular reactions, and was seen in the areas of the valve under stress. The degenerative changes were more severe in the left side than in the right side of the total artificial heart. These findings suggest that mechanical damage to the tissue plays an important role in the pathogenesis of calcification.

Animals↗
PubMed1979

The human dura mater valve. Fabrication methods.

We have used a glycerol-treated human dura mater valve as a valve substitute of the blood pumps for more than 3 years. In comparative studies, it was shown that the dura mater valve is more durable than the glutaraldehyde-treated bovine aortic valves, and thought to be a very attractive valve material. Fabrication methods both for rigid and flexible stents were introduced.

Acrylic Resins↗