Yuzuru Kagawa

Experimental and clinical evaluation of a sack-type ventricular assist device and drive system

A newly designed ventricular assist device and driving system, including an automatic control system, is presented. The blood-contacting surfaces of the blood pump are coated with either Cardiothane or Cardiomat. The system was tested in experiments on goats, whereby only one of fifteen animals showed sudden thrombus formation after 34 pumping days. The system was also applied in three clinical cases for durations of 18 h, 2 days, and 5 days. In two of the cases, weaning could not be performed because of continued bleeding, and the other patient is still alive. No gross findings of thrombus formation were observed in any of the cases, except for a thin circular thrombus at the junction of the connectors and the sack of the blood pump.

Surgical Treatment of Annuloaortic Ectasia: Experience in 7 Consecutive Patients

Seven patients with annuloaortic ectasia were treated according to the method described by Bentall and De Bono. A Björk-Shiley valve in a composite graft was the prosthesis of choice and was used in all patients except 1, who received a Starr-Edwards valve. Profound topical cooling without selective coronary perfusion was applied in 5 patients for myocardial preservation during aortic occlusion. The was 1 operative death and 1 late death, the latter from cerebral thromboembolism. Five survivors have been followed from 1 year 5 months to 2 years 10 months with an average follow-up of 2 years. Excellent results were obtained in all survivors, their physical capabilities putting them in Class I of the New York Heart Association Functional Classification. Postoperative aortograms showed no signs of kinking or compression of vascular prostheses nor abnormalities of prosthetic calves. A modified technique to secure graft fixation is discussed.

Clinical experience with ventricular

Since November 1984, eight postcardiotomy patients with ages ranging from 13 to 65 years, have received ventricular assist devices (VADs) at our institute. All the cases fulfilled the criteria for acute profound ventricular failure despite the administration of a large amount of catecholamines and application of intra-aortic balloon pumping (IABP). The original diseases were acute myocardial infarction (AMI) in two, left ventricular (LV) aneurysm in one, severe acquired valvular disease in three, and congenital cardiac anomaly in two cases. Of the eight cases, three with critical preoperative hemodynamic conditions underwent surgery with VAD on standby. The reasons for applying the VAD were difficulty in weaning from extracorporeal circulation (ECC) in five and low cardiac output syndrome after weaning from ECC in three cases. Two types of VAD system were used in this series. VAD systems developed at the University of Tokyo were used in the initial six cases and a blood pump (TH-7), and multipurpose driving system, which were newly developed at our institute, in the most recent two cases. The duration of assistance varied from 18 h to 70 days. Three cases were not weaned from VAD—two because of incomplete surgical repair and one because of multiple organ failure (MOF) after prolonged assistance for 70 days. Of the five patients who were weaned from VAD, two are alive. The remaining three patients were weaned from VAD and died on the 21st, 97th, and 123rd postoperative days. The cause of death was mainly MOF, originating from various complications such as acute renal failure, sepsis, respiratory failure, and cerebral embolism.

FROZEN SECTION DIAGNOSIS OF HYPERTENSIVE PULMONARY VASCULAR CHANGES AT SURGERY FOR CONGENITAL HEART ANOMALIES

Frozen sections of lung biopsy were prepared in 30 cases of congenital heart anomalies with pulmonary hypertension, and evaluation of severity of the pulmonary vascular changes was made during the surgery. Statistically, significant difference was not found between the diagnosis made by frozen sections and those made by paraffin sections. It is concluded that rapid and accurate diagnosis of pulmonary vascular changes can be made by means of frozen section diagnosis. This method will prove to be clinically important by assisting during operation in rapid assessment of indication for total correction of congenital heart anomalies. ACTA PATHOL. JPN. 35 : 803–807, 1985.

Flow Visualization of Artificial Heart.

Flow visualization techniques were utilized to obtain flow dynamical characteristics of artificial heart using polystylene particles as a flow tracer. In pump filling, circulating flow along with the inner surface of the device which prevents to cause stagnation and turbulence of the flow, was observed.In the post valvular area, turbulent flow was recorded for 8 cm. Continuous Doppler flowmetry in the same region showed less flow values than actually measured flow because of its turbulent flow patterns.