Biomedical subjects

Masahiro Aizaki

Publications and source records attributed to Masahiro Aizaki.

4 recordsLinked to original sources

PubMed2004

A second mitral valve replacement in a patient with hereditary hemorrhagic telangiectasia (Osler's disease).

A 62-year-old female with Osler's disease was admitted to our hospital because of fever and cardiac failure. The patient had undergone a mitral valve replacement (MVR) using a Carpentier-Edwards prosthetic valve 14 years earlier. A bacterial examination of arterial blood identified Streptococcus mitis. No arteriovenous malformations were detected in visceral organs. The patient underwent MVR using the same prosthetic xenograft after conservative treatment and management of repetitive epistaxis and decayed teeth. Intra- and postoperative bleeding were typical of a mitral valve reoperation. This is the first reported experience, to the best of our knowledge, of a second MVR in a patient with Osler's disease.

Endocarditis, Bacterial↗

PubMed2002

The optimal pressure for initial flush with UW solution in heart procurement.

OBJECTIVE: University of Wisconsin (UW) solution is widely used in organ preservation. Some investigators have reported that high pressure during initial flush with UW solution may induce vasoconstriction and endothelial damage, because of its high potassium content and high viscosity. However, using lower pressure during the initial flush may lead to irregular distribution of the solution and incomplete flushing of blood components from coronary vascular beds. This experimental study evaluated the effects of a range of initial flush pressures during heart procurement, followed by orthotopic transplantation of the graft after 12 hours of preservation. MATERIALS AND METHODS: Twelve pairs of adult mongrel dogs, weighing 9 to 14 kg, formed the recipient-donor combinations. After determining hemodynamic status by measuring cardiac output, left ventricular pressure (LVP), and maximum positive and negative change in LVP (+/-LVdP/dt), donor hearts were excised. Coronary vascular beds were flushed with 4 degrees C UW solution at a pressure of 60 mm Hg in the low-pressure group (n = 6) and at 120 mm Hg in the high-pressure group (n = 6). After 12 hours of cold preservation, orthotopic transplantation was performed using cardiopulmonary bypass (CPB). The hemodynamics of the transplanted graft were assessed by comparing recovery rates (%) from donor hearts 2 hours after weaning from CPB. Endothelin-1 (ET-1) levels were measured in the blood obtained from the coronary sinus 30 minutes after reperfusion. The transplanted grafts were then harvested for histologic study and measurement of adenosine triphosphate (ATP) content. RESULTS: Cardiac output, LVP, LVdP/dt and myocardial tissue ATP content were significantly better (p < 0.05) in the high-pressure group than in the low-pressure group. We found no significant differences in ET-1 levels between the groups. Transmission electron microscopic findings revealed that degeneration of the mitochondria was less extensive in the high-pressure group than in the low-pressure group. We observed no obvious ultrastructural damage to the endothelial cells in either group. CONCLUSION: When using UW solution in heart procurement, high pressure is better to completely wash out the blood components and distribute the solution.

Adenosine↗

PubMed2002

Early results and operative considerations of endoventricular circular patch plasty for ischemic cardiomyopathy.

Seven patients with ischemic cardiomyopathy who underwent elective endoventricular circular patch plasty (EVCPP) were included in this study. The mean age of the patients at the time of surgery was 63 years old. All seven patients had anterior left ventricular aneurysms following old myocardial infarction. Two patients were graded NYHA class II, 4 patients class III, and one patient class IV. EVCPP was performed under cardiac arrest with moderate hypothermia in five patients. The two most recent patients underwent EVCPP under on-pump beating and normothermia. Coronary artery bypass grafting was conducted in all cases and the mean number of grafts was 1.8, ranging from one to three. The mitral valve was replaced in one patient. One patient died of myonephrotic metabolic syndrome caused by ischemia of the lower limb. In the follow-up of six patients, the left ventricular end-diastolic volume index (LVEDI) decreased significantly from 128 +/- 31 mL/ m2 to 108 +/- 37 mL/m2. Left ventricular end-systolic volume index (LVESI) decreased in five patients. Left ventricular end-diastolic and end-systolic diameter remained unchanged after surgery. The left ventricular ejection fraction (LVEF) increased from 0.28 +/- 0.08 to 0.321 +/- 0.1. LVESI and LVEF did not improve in one patient with a large residual dyskinetic area at the distal LV septum. A residual dyskinetic area at the distal LV septum was observed in two of four patients who underwent EVCPP under cardiac arrest. This condition, however, was not detected in two patients who underwent EVCPP under on-pump beating conditions. In the follow-up study, the grade of NYHA functional classification improved in all six patients. In conclusion, EVCPP under on-pump beating is a realistic and effective procedure with which to complete ideal LV geometry and promote good results in patients with ischemic cardiomyopathy.

Aged↗

PubMed2001

The Effect of Coronary Perfusion with an Oxygenated Celsior Solution on 12-hour Cardiac Preservation.

Celsior is a new extracellular-type cardiac preservation solution. We recently developed an apparatus for preservation using low-pressure continuous coronary perfusion. The purpose of this study was to investigate the efficacy of coronary perfusion with an oxygenated Celsior solution using the new apparatus for prolonged cardiac preservation. Adult mongrel dogs weighing 9-13 kg were divided into two groups: the coronary perfusion group (CP; n = 5) and the simple immersion group (SI; n = 7). The coronary vascular beds were washed out with a 4 degrees C Celsior solution following cardiac arrest using the same solution, and their hearts were excised. In the CP group, the graft was immersed in a 4 degrees C Celsior solution and perfused with the same oxygenated solution. In the SI group, the graft was simply immersed in a 4 degrees C Celsior solution. beta-adenosine triphosphate (beta-ATP), phosphocreatine (Pcr), inorganic phosphate (Pi) levels and myocardial pH (pHi) were measured immediately after excising the heart, and at 3, 6, and 12 hours after preservation. beta-ATP, Pcr, and Pi values were expressed as a percentage of control values, which were measured immediately after excising the heart. beta-ATP/Pi and Pcr/Pi levels were significantly higher in the CP group than in the SI group at 6 and at 12 hours after preservation. The pHi levels during preservation were significantly higher in the CP group than in the SI group. Low-pressure hypothermic coronary perfusion with an oxygenated Celsior solution is effective for long-term heart preservation. </hea

Journal Article↗