Japanese Journal of Cardiovascular Surgery

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It has been known that the ventricular assist device (VAD) is effective in severe ventricular failure refractory to conventional drugs and the intraaortic balloon pumping. In the future, it is expected to employ biventricular assist device (BVAD) for the patients with cardiogenic shock more frequently. Until recently, BVAD were successfully applied in a few instances unfortunately. The purpose of this experimental study is to evaluate the effect of right ventricular assist device (RVAD) and BVAD on biventricular failure with profound right ventricular failure. Biventricular failure was induced by pulmonary artery banding and ligation of left anterior descending coronary artery in 18 pigs. RVAD (10 pigs) was applied in the group I, and BVAD (8 pigs) was done in the group II. In the group I, right ventricular assistance caused increases in LAP, LVEDP and decreases in AoP, LV_max dp/dt with deterioration of left ventricular failure when the pump flow ratio (RVAD flow/total flow) exceeded 50%. On the contrary, in the group II, LAP and PAP decreased and left ventricular failure improved with biventricular assistance. Consequently BVAD could maintain the systemic circulation. The flow volume of LVAD unchanged in increasing in the flow volume of RVAD. This phenomenon seemed related to the effect of pulmonary circulation. These results suggested that in the case of biventricular failure, concomitant support of LVAD and RVAD was extremely effective for the prevention of latent left ventricular failure induced by right ventricular assistance.

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Left heart bypass was performed with Bio Medicus Co.-made Bio-pump, a representative centrifugal pump. A vinyl chloride tube for the usual cardio-pulmonary bypass not treated with antithrombogenic material. was used in the bypass circuit. In the experiment, the mongreal adult dogs were divided into the systemic heparinized group and non-heparinized group and the bypass was performed for 6 hours. As a result, coagulation and fibrinolysis were more activated in the non-heparinized group than the other group. So, when this method is used clinically, a small quantity of heparin should be administered. Clinically, this approach was used as an adjunct in operation for 7 cases of thoracic aortic aneurysm. During left heart bypass, a small quantity of heparin (0.5-1.0mg/kg) was administered. A rise in FPA and FDP considered attributable to autotransfusion during the operation was noted. Distal perfusion could be performed fully and the amount of bleeding during and after operation was small, but 1 case each of acute renal failure and paraplegia as postoperative complication was encountered. Neither was considered due to left heart bypass; and, changes in respiratory system and hepato-renal function were considered within the tolerable range. These results have led us to believe that left heart bypass using Bio-pump is safe and useful as an adjunct in operation for thoracic aortic aneurysm and should be used positively in the future.

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In a 73-year-old man, ventricular septal rupture and tricuspid papillary muscle rupture were complicated with inferior acute myocardial infarction (AMI). Twenty-five days after AMI, radical operation was performed. VSR was found 1.5cm diameter at the inferior septum and directly closed using teflon felt strip. Infarctectomized inferior LV free wall was closed with woven Dacron patch which was cut from Cooley low porosity aortic tube graft and sutured with bovine pericardium facing to LV cavity. A part of anterior tricuspid papillary muscle was found to be ruptured. Tricuspid valve replacement was performed with Carpentier-Edwards valve. One and half year postoperatively, the patient has been doing well without heart failure. To our knowledge, this is the first case of VSR complicated with tricuspid papillary muscle rupture following AMI.

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