Sohei Suzuki

A prostacyclin analogue reduces free radical generation in heart-lung transplantation

The mechanism by which prostacyclin acts to prevent in vivo reperfusion injury is still uncertain. This study was therefore undertaken to assess the effect of a stable prostacyclin analogue (OP 41483-alpha-CD [OP]) on oxygen-derived free radicals after heart-lung transplantation. OP was administered to the heart-lung graft through the pulmonary artery for 25 minutes encompassing the reperfusion process. Free radicals were directly measured by electron spin resonance spectroscopy. The radical intensities of pulmonary venous blood were significantly lower in the OP group than in the control group, suggesting that fewer free radicals were generated in the lungs of the OP group. The cardiac and respiratory function were better in the OP group than in the control group. The lung is the primary source of oxygen free radical attack, and the beneficial action of OP on free radical generation is almost exclusively restricted to the lung and does not apply to the heart. This result suggested that OP probably is effective in inhibiting free radical generation from the endothelium.

Left ventricular function studies in constrictive pericarditis

Left ventricular function studies were performed on five patients with constrictive pericarditis. Functional data were obtained from intracardiac pressure measurements and cineangiocardiographic films. Left ventricular end-diastolic volume(LVEDV), left ventricular end-systolic volume (LVESV), ejection fraction (EF), stroke work index (SWI), circumferential fiber shortening, and percent circumferencial shortening were significantly below normal values in the five cases. These changes are reflected mainly in the degree of pericardial restriction. Reduction in mean Vcf was also observed. Theoretically, the velocity of ventricular internal circumferential shortening is also affected by changes in ventricular volume or resting myocardial fiber length, however, in patients with constrictive pericarditis, reduction in mean Vcf suggests left ventricular dysfunction. Our clinical studies indicate that evaluation of mean Vcf is valuable in the assessment of postoperative prognoses.

Progressive pulmonary vascular disease after pulmonary artery banding and total correction in a case of ventricular septal defect and pulmonary hypertension

A 7-month-old infant with ventricular septal defect and pulmonary hypertension underwent pulmonary artery banding, which resulted in a decrease in the pulmonary arterial peak pressure from 102 to 54 mmHg. Lung biopsy findings showed at most an early grade 3 Heath-Edwards classification, and an index of pulmonary vascular disease of 1.4, both of which indicated operability for total correction. Small pulmonary arteries less than 100 microns in diameter, however, showed marked hydropic changes in the medial smooth muscle cells. Total correction was performed at the age of 2 years, but the pulmonary arterial pressure failed to decrease. A lung biopsy taken just after the closure of the ventricular septal defect contraindicated operability due to progressive pulmonary vascular disease at a grade 6 Heath-Edwards classification and an index of pulmonary vascular disease of 2.4. The patient died at 8 months after the operation, and an autopsy revealed still more advanced pulmonary vascular disease at a grade 6 Heath-Edwards classification and an index of pulmonary vascular disease of 2.8. The pathogenesis of arterial changes is discussed.

Replacement of the Canine Inferior Vena Cava with a Seeded Graft

Abstract The patency and microscopic findings of gelatin-coated Dacron grafts seeded with endothelial cells and implanted into the inferior vena cava of dogs was evaluated. A total of 25 mongrel dogs were divided into four experimental groups according to whether or not an antiplatelet agent was administered and a seeded or nonseeded graft was implanted. In the groups not given antiplatelet therapy that were implanted with a nonseeded graft, occlusion of the graft occurred soon after surgery. In contrast, in the majority of animals implanted with a seeded graft and given antiplatelet therapy, graft patency was evident for up to 4 weeks postoperatively. In the latter animals, scanning electron microscopy 4 weeks after surgery showed the formation of confluent endothelial-like cells within 5 mm from the anastomosis, as well as insular endothelial-like cells in the central part of the graft. The simple centrifugal seeding method enables endothelial-like cells to adhere to grafts, suggesting that it may be useful in venous replacement.

Nafamostat mesilate modulates the release of platelet-activating factor during left ventricular assistance with hemofiltration in canine heart failure.

OBJECTIVE The enhanced generation of various chemical mediators is regarded as one of the mechanisms by which severe heart failure progresses to multiple organ failure. Platelet-activating factor is a phospholipid mediator which plays an important role in inflammatory reactions and circulatory shock. We studied the changes in platelet-activating factor levels in a canine heart failure model treated with a left ventricular assist device and hemofiltration, and assessed the effect of a protease inhibitor, nafamostat mesilate. METHODS Twenty dogs underwent multiple coronary ligations, and at 2 hours after the ligations they were maintained on left ventricular assist device support with continuous hemofiltration. The animals were divided into two groups: a nafamostat group (n = 10) that received nafamostat mesilate (2 mg/kg/hr), and a control group (n = 10) that received vehicle only. RESULTS The blood platelet-activating factor level, before coronary ligations, in the control and nafamostat groups was 2.3 +/- 0.4 and 2.0 +/- 0.7 ng/ml, respectively, and the coronary ligations had little effect on the platelet-activating factor. However, after the initiation of left ventricular assist device, the platelet-activating factor in the control group (5.6 +/- 2.2) was significantly higher (p < 0.05) than that in the nafamostat group (1.1 +/- 0.3). Nafamostat administration was also effective in controlling the increase in the blood lactate level. Hemofiltration did not change the platelet-activating factor. CONCLUSIONS We concluded that platelet-activating factor may play a critical role in the development of severe heart failure with left ventricular assistance, and nafamostat administration is likely to be beneficial in such a critical condition by suppressing the platelet-activating factor level.

Reoperative coronary artery bypass grafting without cardiopulmonary bypass

Between October 1995 and February 1997, 2 men and 4 women aged 53 to 75 years (mean, 66.3) underwent reoperative coronary artery bypass grafting without cardiopulmonary bypass. Isolated reoperative circumflex or intermediate artery bypass was performed through a left thoracotomy (n = 2), reoperative bypass to the left anterior descending coronary artery was performed through a median sternotomy (n = 3), and bypass to the right coronary artery was performed through an upper median laparotomy (n = 1). Single coronary bypass grafting utilizing arterial grafts (left internal thoracic artery: 3, right gastroepiploic artery: 3) was performed in all cases. There were no operative deaths. All cases required neither cathecolamine nor intraaortic balloon pumping). Peri/post operative blood transfusion was necessary in only one case. Postoperative coronary angiography revealed that the 6 arterial grafts were patent. Reoperative coronary artery bypass grafting without cardiopulmonary bypass can be performed with low perioperative morbidity and mortality, easy postoperative management, satisfactory graft patency, and good symptomatic improvement.

A Case of Primary Cardiac Angiosarcoma.

原発性心臓腫瘍のなかで血管肉腫はまれな疾患で, 比較的若年男子に好発し予後が著しく不良な疾患である. 今回われわれは右心室穿孔による心タンポナーデを初発症状として発症した本疾患の1例を経験した. 穿孔部の心筋の病理組織学的検索では原因不明で, そのまま退院となった. しかし1か月後に突然, 多量の喀血をきたし緊急来院した. 気管支鏡で右B6からの大量の出血があり, 止血困難と判断し緊急手術で右肺下葉切除を行った. 出血巣の病理組織学的検索で血管肉腫と診断された. 前回の右室心筋を再検討したところ, 肺病巣と同一な腫瘍細胞が検出され, この時点で心臓穿孔は心臓の血管肉腫によるものと判明した. 患者は再入院時にすでに両肺野に多発性の転移を認めており, 化学療法を主体とした治療を行わざるをえなかった. 一時寛解したが1か月後に再び多数の転移性陰影を認めるようになり, 呼吸困難を呈し発症後9か月で死亡した. 本疾患の確定診断は悪性腫瘍細胞を証明することであり, 術前診断は非常に難かしい. もし生前に診断が可能であっても有効な治療手段がなく, 今後の有効治療の開発が待たれる.