Goro Ohtsuka

Tricuspid valve replacement with the bileaflet St. Jude Medical valve prosthesis

Case histories of 39 patients who underwent tricuspid valve replacement with the St. Jude Medical prosthesis between June 1979 and August 1992 were reviewed in March 1993. The average patient age at the time of the operation was 46 +/- 11 years (range from 17 to 68 years). Concomitant mitral and/or aortic valve replacements were performed in 30 patients. All patients were given warfarin to maintain thrombotest between 10% to 25%. This number was between 2.8 to 1.6 times the control value in the International Normalized Ratio of prothrombin time. Three operative deaths occurred (7.7%). Among six late deaths, two patients died suddenly of unknown causes, and the remaining patient deaths were not valve-related. The actuarial survival rate at 14 years was 54.7%. Valve thrombosis occurred in one patient and was successfully treated with intravenous urokinase. This was the only valve-related complication (0.67%/patient-year). No reoperations were necessary in the tricuspid position. In conclusion, the St. Jude Medical valve is our choice of prosthesis for tricuspid valve replacement in adult patients who can receive proper anticoagulation therapy.

Less Blood Damage in the Impeller Centrifugal Pump: A Comparative Study with the Roller Pump in Open Heart Surgery

A centrifugal pump with an impeller (Nikkiso Centrifugal Pump, Model HPM15; Nikkiso Co. Ltd.) was applied to cardiopulmonary bypass (CPB) in 14 patients who underwent elective coronary artery bypass grafting. Serum hemoglobin level, platelet count, and serum p-thromboglobulin (pTG) level were measured during CPB. The results were compared with those obtained in a comparative roller pump (RP) group (n = 10). There was no difference in the time on CPB between the NP (109 min) and RP (121 min) groups. The serum pTG level (ng/ ml) was lower in the NP group than in the RP group (obtained 90 min after the initiation of CPB). The plasma-free hemoglobin level also was lower in the NP group than in the RP group (obtained 90 min after the initiation of CPB, 120 min after the initiation of CPB, immediately after the termination of CPB, 3 h after termination of CPB; p < 0.01). There was no significant difference in platelet depletion. The HPM15 pump showed excellent hemodynamic performance with less blood trauma compared with the roller pump in its clinical application to open heart surgery.

Heart valve operation in acromegaly

BACKGROUND Intractable congestive heart failure is known as a serious complication of acromegaly, but valvular heart disease rarely occurs in acromegalic patients. We experienced 5 surgical cases of valvular heart disease associated with acromegaly. We describe the features of those cases in this report. METHODS The patient characteristics and operative and pathologic findings were retrospectively studied. RESULTS There were 4 men and 1 women. Age at operation was 59 +/- 5.5 years. Cardiac lesions consisted of 1 case of aortic regurgitation associated with mitral regurgitation, 1 of aortic regurgitation, and 3 of mitral regurgitation. Operative procedures consisted of 1 double valve replacement (aortic and mitral valve replacement), 1 aortic valve replacement, and 3 mitral valve replacements. The causes of aortic valvular regurgitation were aortic valvular degeneration and aortic annular dilatation. The causes of mitral regurgitation were chordal rupture and mitral valvular degeneration. Histopathologic examination of the excised valves showed mucopolysaccharide deposits and myxomatous degeneration of the leaflets. The myocardium showed fibrosis of interstitial spaces and endocardium, and disarrangement of muscle fibers. CONCLUSIONS We report 5 successful surgical cases of valvular heart disease associated with acromegaly. Earlier operation is recommended for such cases because of acromegalic cardiomyopathy.

LONG-TERM IN VIVO LEFT VENTRICULAR ASSIST DEVICE STUDY WITH A TITANIUM CENTRIFUGAL PUMP

A totally implantable centrifugal artificial heart has been developed. The plastic prototype, Gyro PI 601, passed 2 day hemodynamic tests as a functional total artificial heart, 2 week screening tests for antithrombogenicity, and 1 month system feasibility. Based on these results, a metallic prototype, Gyro PI 702, was subjected to in vivo left ventricular assist device (LVAD) studies. The pump system employed the Gyro PI 702, which has the same inner dimensions and the same characteristics as the Gyro PI 601, including an eccentric inlet port, a double pivot bearing system, and a magnet coupling system. The PI 702 is driven with the Vienna DC brushless motor actuator. For the in vivo LVAD study, the pump actuator package was implanted in the preperitoneal space in two calves, from the left ventricular apex to the descending aorta. Case 1 achieved greater than 9 month survival without any complications, at an average flow rate of 6.6 L/min with 10.2 W input power. Case 2 was killed early due to the excessive growth of the calf, which caused functional obstruction of the inlet port. There was no blood clot inside the pump. During these periods, neither case exhibited any physiologic abnormalities. The PI 702 pump gives excellent results as a long-term implantable LVAD.

Current progress in the development of a totally implantable gyro centrifugal artificial heart

A totally implantable centrifugal artificial heart has been developed using a miniaturized pivot bearing supported centrifugal pump (Gyro Pl pump). The authors report current progress in its development. The Gyro Pl-601 has a priming volume of 20 ml, weighs 100 g, has a height of 60 mm, and has a diameter of 65 mm. This pump can provide 8 L/min against 150 mmHg at 2,250 rpm. It is driven by an miniaturized DC brushless motor with the coils fixed in a plastic mold that is waterproof and made of titanium (weight, 204 g; height, 18 mm; diameter, 65 mm). In this centrifugal artificial heart, two Gyro PI pumps are implanted independently to replace cardiac function without resecting the native heart. Its anatomic and surgical feasibility were confirmed experimentally. The Gyro Pl-601 was implanted as a right or left ventricular assist device in the preperitoneal space of five calves. All five tests proceeded without any thromboembolic symptoms. One of five tests was extended more than 1 month to confirm the long-term feasibility of the Gyro Pl-601 pump system. Based on the satisfactory results of the in vivo tests, the material conversion of the Gyro Pl from polycarbonate to titanium alloy (Ti-6A1–4V) was undertaken to improve its biocompatibility for long-term implantation. ASAIO Journal 1998; 44:207–211.

Long-term results of coronary artery bypass grafting in elderly japanese patients

BACKGROUND This study was undertaken to examine long-term results of coronary artery bypass grafting in elderly Japanese patients. METHODS Of 1,425 coronary artery bypass grafting patients over the last 13 years, 137 patients were 70 or more years old and 1,288 were less than 70 years old. Mean number of distal anastomoses was similar in both groups. Postoperative survival and event-free proportion were estimated by the Kaplan-Meier actuarial method and compared among the groups by Cox-Mantel statistical analysis. RESULTS Operative mortality and the incidence of late cardiac death after coronary artery bypass grafting were equivalent between the elderly and younger groups, although the rates of left main trunk disease, acute myocardial infarction, and emergency operation in the elderly group were significantly higher than those in the younger group. Coronary artery bypass grafting in elderly patients had a relatively high hospital mortality and more late noncardiac deaths, but the incidence of postoperative cardiac intervention in elderly patients was lower than that in younger patients. CONCLUSIONS These results suggest that coronary artery bypass grafting for elderly patients is encouraged as well as is that for younger patients in a representative Japanese population.