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Biomedical subjects

I Kiso

Publications and source records attributed to I Kiso.

47 records · Page 3Linked to original sources
PubMed1976

Hemodynamic effects of venous valves in aorto-coronary bypass grafts.

Use of the saphenous vein in aorto-coronary bypass surgery for treatment of occlusive coronary artery disease is a well-established technique. Use of the mammary artery for the same purpose has also been favorably reported. This study was undertaken to determine whether a vein graft containing a valve would have an added advantage. A comparison of the effect of competent and incompetent valves in vein grafts on the hemodynamics of coronary circulation was made. In a group of 18 dogs, a 5 cm. portion of each dog's cephalic vein containing a valve was used in a single aorto-coronary bypass graft. Flow measurements were made between the valve and the anastomosis of the graft to the left anterior descending coronary artery (LAD). The valve was made temporarily incompetent by the insertion of a spring wire basket, 3.5 mm. in diameter, through the valve via a side branch. The flow of blood through the venous graft with the competent valve was 11.0 +/- 2.6 per cent higher than with the incompetent valve. An analysis of flow patterns showed that this increased flow could be attributed to a reduction of backflow during systole and an increase in forward diastolic flow. Results suggest that postoperative myocardial perfusion is enhanced by the presence of valves in aorto-coronary bypass vein grafts.

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PubMed1976

Permanent in-series cardiac assistance with the dynamic aortic patch: Blood-prosthesis interaction in long-term canine experiments.

The blood-prosthesis interaction of the dynamic aortic patch (DAP), an in-series assist device for permanent circulatory support which is implanted in the descending thoracic aorta, was studied in 65 long-term experiments. Periods of postoperative observation with the device inactive or activated ranged from 2 weeks to 22 months. The intravascular surface of the DAP, fabricated of Dacron velour backed by bioelectric polyurethane, displayed various degrees of organization, ranging from a thin fibrin layer to a well organized pseudointima. Activation of the system did not prevent the development of an organized pseudointima. Changes in free-plasma hemoglobin were minimal; platelet count per square millimeter and state of reactivity remained within normal limits. Evidence of renal embolization, attributable to activation of the device, was found in five animals. Frequent lethal complications were aortic rupture and infections of the thoracic cavity originating at the implantation site. Further improvement of the DAP and the techniques of implantation is indicated to insure its efficacy during long-term implantation and activation.

Animals↗
PubMed1975

Demonstration of lack of persistence of effectiveness of intra-aortic balloon pumping of short duration in acute myocardial ischemia.

Experimental studies were carried out to quantitate the effectiveness of intra-aortic balloon pumping (ABP) in reducing severity and extent of myocardial ischemia and the persistence of induced changes after cessation of pumping. Ligation of the anterior descending coronary artery was followed by one hr of observation, IABP for one hr (12 dogs) or 3 hrs (12 dogs) and an additional one hr of observation. Epicardial mapping utilizing 20 electrodes was used to obtain the ST segment elevations (Sigma ST) and numbers of electrodes showing ischemic ST CHANGES (NST) in each group. Reductions of SigmaST of approximately 15% and 33% and reduction of NST of 15% and 20% was observed in the one and 3 hr groups respectively, and persisted throughout the period of pumping. Both parameters were noted to increase within 5 mins after cessation of IABP in both groups. SigmaST frequently rose to almost pre-IABP values in the group pumped for one hr. The group pumped for 3 hrs showed SigmaST increase of approximately 15% and NST increase of approximately 16%. Hemodynamic measurements showed in both groups a mean systolic unloading of approximately 10% and 10-20% mean diastolic augmentation. In conclusion, IABP of short duration (1-3 hrs) early after the onset of acute ischemis (one hr) induces a significant but transient decrease in SigmaST and NST, which reflects a reduction in myocardial ischemia. Further study is required to evaluate the effectiveness of intra-aortic balloon pumping, if intitated several hours after the onset of ischemia, to reproduce the clinical reality of a patient with an acute myocardial infarction.

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PubMedDate not supplied

Autologous arterial grafts grown on polyester molds: observations of graft growth and patency in experimental animals.

Tissue molds consisting of polyester mesh jackets covering silicone mandrils were implanted subcutaneously in dogs. When a sufficiently strong layer of connective tissue had formed around the molds they were excised and the mandrils removed. The process of tissue formation was observed and recorded. The forms were used as grafts in either the abdominal aorta or the femoral artery of the dog. Six grafts 10 mm inner diameter, six grafts 6 mm inner diameter and 26 grafts 3 mm inner diameter were implanted. After 4.5 months 80% of the 10 mm grafts, 83% of the 6 mm grafts, but only 4% of the 3 mm grafts remained patent. Histological studies at various intervals after grafting revealed gradual thickening of the neointima. The reason for graft failure was thrombus formation originating at the line of anastomosis.

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