[Surgical treatment of transcardiac expansion of ingrowing chondrosarcoma].
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Adult↗
Biomedical subjects
F Miyawaki
Publications and source records attributed to F Miyawaki.
[Open heart surgery for removal of secondary cardiac tumors].
Recent remarkable development of the non-invasive diagnostic apparatus such as two dimensional echocardiography, computed tomography and RI angiography improves early diagnosis for secondary cardiac tumors and promotes surgical treatments for them. Five cases of secondary intracardiac tumors underwent open heart surgery using cardiopulmonary bypass with successful removal. Although a case of direct invasion of a malignant thymoma into the pericardium, RA and SVC was lost at ICU after surgery because of massive hemorrhage followed by LOS, another 4 cases, i.e., a 27 year-old female with implantation of LA myxoma into the RA and RV, a case with intracavitary extension of leiomyosarcoma of the IVC, a case of intravenous extension of the uterine leiomyomatosis through the IVC to the pulmonary artery and a case of intravenous extension of chondrosarcoma of the left fibula to the heart are alive actively. Open heart surgery has become acceptable treatment for cases with secondary intracavitary cardiac tumors in order to rescue emergency cases with circulatory obstruction by the tumor mass, to make sure a pathological diagnosis of unknown origin and to promote further chemotherapy and/or radiation therapy after surgery. Our surgical results may support these active treatments for secondary cardiac tumors.
Adult↗
Split-circulation assist device facilitates heart failure management and increases effects of intra-aortic balloon pumping.
The split-circulation assist device (SCAD) comprises an intra-aortic balloon pump (IABP), percutaneous cardiopulmonary support (PCPS) equipment, and two occlusion balloons that occlude the descending thoracic aorta by alternate inflation. With the SCAD, the failing heart, assisted by IABP, maintains only the upper 25-30% of the entire circulation without any interference by bypass flow from PCPS. An animal experiment indicated that a given rise in cardiac output caused an increase in aortic pressure in the SCAD group about three times greater than that in the control group (an ordinary combination of IABP and PCPS). Thus, by causing greater increases in arterial pressure, the SCAD may make possible detection of subtle increases in cardiac output, and therefore early detection of cardiac recovery. Multiple regression analysis from the pressure and flow data obtained in another experiment indicated that the SCAD facilitated the prediction of cardiac outputs and loads by preventing the bypass flow rate from influencing the aortic pressure. In addition, the SCAD may enhance cardiac assistance by increasing the effects of IABP. Therefore, the SCAD is a useful and potent new circulatory assist device that can facilitate both timely weaning from PCPS and heart failure management.
Animals↗
Recovery directed left ventricular assist device: a new concept.
To promote cardiac recovery, we developed a recovery directed left ventricular assist device (RDLVAD) that consists of a valved apical conduit, an afterload controlling chamber (ACC), and a pump. We evaluated its efficacy by comparison with an ordinary LVAD. In each of six pigs with ischemia-induced heart failure, flow and pressure measurements were made while maintaining the total blood flow and arterial pressure equal in the two groups. RDLVAD was able to direct all the blood ejected from the LV into the ACC (0-15 mm Hg) but not into the aorta (73 mm Hg). In the ordinary LVAD, however, some ejection occurred into the aorta despite vigorous suction of the LV. Thus, RDLVAD increased DPTI/SPTI 2.3 times (p < 0.005) and decreased left ventricular end-diastolic pressure by 40% and maximum dP/dt by 20% (p < 0.05). Even the apical valve, at approximately half the diameter of the aortic valve, was able to allow all the blood ejected from the LV to enter the ACC. In one control group pig that achieved almost no ejection into the aorta, left ventricular relaxation and dilatation was extremely limited. RDLVAD may promote cardiac recovery by ensuring less LV work, a greater blood supply/demand ratio in the coronary circulation, and full ventricular relaxation.
Animals↗
Influence of static pressure and shear rate on hemolysis of red blood cells.
The purpose of this study was to investigate the effect of multiple mechanical forces in hemolysis. Specific attention is focused on the effects of shear and pressure. An experimental apparatus consisting of a rotational viscometer, compression chamber, and heat exchanger was prepared to apply multiple mechanical forces to a blood sample. The rotational viscometer, in which bovine blood was subjected to shear rates of 0, 500, 1,000, and 1,500 s(-1), was set in the compression chamber and pressurized with an air compressor at 0, 200, 400, and 600 mm Hg. The blood temperature was maintained at 21 degrees C and 28 degrees C. Free hemoglobin at 600 mm Hg was observed to be approximately four times higher than at 0 mm Hg for a shear rate of 1,500 s(-1) (p < 0.05). The results suggest that the increase in hemolysis is strongly related to pressure when high shear rates are applied to the erythrocytes. The data acquired in this study will be helpful in the development of artificial organs, where it will facilitate the prediction of hemolysis in flow dynamics analysis, flow visualization, and computational fluid dynamics.
Blood Viscosity↗
Low density lipoprotein apheresis during cardiopulmonary bypass of hypercholesterolemic patients.
Ischemia-reperfusion injury in open heart surgery can cause atherosclerotic changes in both bypass grafts and native coronary arteries by increasing endothelial permeability and allowing excessive influx of LDL into the subendothelium. The authors used LDL apheresis during cardiopulmonary bypass (CPB) to actively remove serum LDL before reperfusion, minimizing LDL influx. They evaluated the efficacy and safety of this new procedure in eight hypercholesterolemic patients. The control group consisted of 41 patients. Mean LDL cholesterol (LDL-C) level on admission was 180 +/- 41 (SD) in the LA group and 139 +/- 32 mg/dl in the control group (p = 0.02). After 105 +/- 27 min of apheresis, the LDL-C level in the LA group decreased to 62 +/- 25 mg/dl (reduction rate: 59 +/- 18%). In contrast, in the control group, the LDL-C level was reduced to 117 +/- 41 mg/dl (reduction rate: 16 +/- 9.5% [P = 0.0001]) after CPB. No significant difference was observed in intraoperative blood loss, postoperative blood loss, platelet count, prothrombin time, activated partial thromboplastin time, incidence of wound complications, or early patency rate of bypass graft between groups. Low density lipoprotein apheresis during CPB is a safe and effective method for lowering serum LDL level sufficiently before reperfusion, and can adequately reduce LDL influx into the vessel wall.
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