The myocardial catecholamine metabolism was investigated to elucidate the mechanism of the depletion of myocardial catecholamine stores in hypertrophied and failing hearts of rabbits. Myocardial catecholamine concentration was already reduced in early stage of cardiac hypertrophy, and similar time course changes were observed in the activity of tyrosine hydroxylase, the rate-limiting enzyme in the biosynthesis of catecholamine. These findings suggest that the depression of tyrosine hydroxylase activity is a main factor contributing to the depletion of myocardial catecholamine stores. The changes of the enzymatic destruction, the release and the uptake of catecholamine in hypertrophied and failing hearts were also observed and discussed.

View full abstract

The vascular reactivity in the internal carotid artery, external carotid artery and brachial artery during induced hypertension (intravenous administration of noradrenalin) was investigated in man in situ simultaneously by means of the ultrasonic Doppler apparatus equipped with a newly devised probe and on-line real-time data processing system. The hemodynamic autoregulation and/or nor-adrenalin sensitivity is generally higher in the internal carotid artery than In the external carotid artery. However, there seem to be some subjects in whom vascular reactivity is opposite or antagonistic to the above pattern. Therefore, it is suggested that the vascular reactivity in these three arteries is indefinite and complicated according to the subjects.

View full abstract

Many investigators have studied the effectiveness of various types of assisted circulation to relieve the failing heart. Counterpulsation (C-P) and Selective Left Ventricular Bypass (SLVB) are powerful procedures for mechanically supporting the left-sided heart. The former is efficacious for reducing the left ventricular pressure work, the latter for it's volume work mainly. Theoretically, synchronization of the pump action with the cardiac cycle is desirable for assisting the failing left ventricle. A combined method of SLVB and C-P will probably reduce the left ventricular work markedly, and there-fore, it will be the most reasonable assisted circulation for left-sided heart failure. This method is named Selective Left Ventricular Partial Bypass with Counterpulsation (Sy. PB) by the author. The Standard Isochronous Myocardial Augmentation System (SIMAS^○!R) was used as a specially designed pump equipped with a synchronizing device with ECG required for this purpose, and with SIMAS it was easy to obtain proper synchronization of the pump action with ECG. SIGMAMOTOR Model TM-2 was used as a pumping device in the cases of asynchronous bypass. After a thoracotomy and laparotomy done, an arterial cannula made of rigid polyethylene for counterpulsation was inserted through the abdominal aorta into the thoracic aorta. In group I (of 4 healthy mongrel dogs), the bypass techniques performed were SLVB without a left ventricular vent (TB-Vc), SLVB with a left ventricular vent (TB-Vo) and Asynchronous Selective Left Ventricular Partial Bypass (Asy. PB) ; in group II (of 5 healthy mongrel dogs), TB-Vc, Asy. PB and Sy. PB were performed.

View full abstract

Since 1957, through the serial experimental and clinical investigations by Akune and co-workers, various types of assisted circulation have been classified according to indicated pathological states as follows : (R) Assisted Circulation for Right-Sided Heart Failure 1) Selective right ventricular bypass 2) Veno-arterial pumping 3) Partial cardio-pulmonary bypass (PCPB) (L) Assisted Circulation for Left-Sided Heart Failure 1) Selective left ventricular bypass 2) Counterpulsation (CP (A-A)) 3) Combination of R₁ and L₂ (B) Assisted Circulation for Combined Left- and Right-Sided Heart Failure 1) Total cardio-pulmonary bypass 2) Combination of R and L Although a considerable number of reports about assisted circulation for left- or right-sided heart failure have been appeared in recent years, little work has been done to study assisted circulation for both left- and right-sided heart failure. The purpose of this investigation is to establish such a form of circulatory assist system for both left- and right-sided heart failure that can be employed using peripheral cannulation in the emergency room or even at the bedside. A combined method of counterpulsation and PCPB, (CP(V-A)), would appear to be a suitable circulatory assist system fulfilling the above mentioned conditions, because of the following reasons : 1) CP (A-A) circulatory assist system functions only left ventricular supports, while CP (V-A) does not only left ventricular supports but also right one for the reason of using a PCPB circuit, so that CP (V-A) would be efficacious in both the left- and right-sided heart failure. 2) The left ventricular pressure work load alone can be reduced with CP (A-A), on the other hand, both pressure and volume work loads of the left ventricle would be reduced with CP (V-A), so that the left ventricular function could be more efficiently supported with CP (V-A) than with CP (A-A).

View full abstract

A considerable amount of research has been reported on the effect of counterpulsation, a method of assisted circulation. It seems well established that counterpulsation reduces the left ventricular work load, but controversy continued as to whether coronary blood flow is increased by counterpulsation. The present study was designed to investigate the hemodynamic effects of counterpulsation on an intact dog, especially its effects on coronary blood flow and aortic mean pressure. Materials and Methods Counterpulsation (CP) was performed using a Standard Isochronous Myocardial Augmentation System (SIMAS) with a rigid polyethylene cannula inserted from the abdominal aorta into the middle portion of the thoracic descending aorta. Thirty-one experiments were made using 17 healthy adult mongrel dogs weighing 11-20 kg. They were anesthetized with intravenous pentobarbital sodium (25-40 mg/kg) followed by the administration of a mixture of ether and oxygen through an intratracheal tube. Respiration was controlled by a manual method. The heart was exposed by a bilateral anterior thoracotomy. Aortic pressure was monitored with a strain gauge pressure transducer connected to a catheter inserted into the aortic arch via the axillary artery. Left and right ventricular pressure were monitored each with a strain gauge transducer connected to a short catheter punctured into the ventricle. Coronary sinus blood flow was measured directly through a catheter inserted and secured in the coronary sinus via the right atrial appendage. Myocardial oxygen consumption was measured by gasmetry with an IL Meter Model 113 and hemoglobinometry with a hemoglobinometer. To evaluate the cardiovascular response, the following parameters were adopted : aortic mean pressure (AMP), aortic systolic mean pressure (ASMP), aortic diastolic mean pressure (ADMP), left ventricular systolic mean pressure (LVSMP), right ventricular systolic mean pressure (RVSMP), coronary sinus blood flow (CSF), myocardial oxygen consumption (qO₂), and TTI. Each parameter is measured before and during CP. According to the procedure and result, experiments were divided into the following groups : I (a+b) : 24 experiments in which CP was performed under normovolemic condition, I (a) : 15 experiments in which CSF was reduced in group I (a+b), I(b) : 9 experiments in which CSF was increased in group I(a+b), II : 7 experiments in which aortic mean pressure was slightly elevated by means of transfusion during CP.

View full abstract

The cerebral, coronary and renal arteriosclerosis are now the main causes of death in the aged. The outlook for better health and longer life for our aging population rests, in large measure, upon elimination of vascular disease as a cause of death and disability. Arteriosclerosis in all probability has no single cause. It results most likely from a combination of factors. Among them presently implicated are heredity, diet, morphologic and chemical anatomy of the blood vessel wall, arterial blood pressure, lipid content of blood, and sex. Animal experimentation and epidemiological results have suggested that changes in the diet may be partially responsible for the increased incidence of arteriosclerosis. The approach to the problem by animal experiments has shown that arteriosclerosis, similar to but not identical with that of the human type, can be produced in a variety of experimental animals by dietary variations. Many kinds of diets have been used : some are deficient in one or more nutrients, others contain excessive amounts of certain constituents or combine excess of one with deficiency of another. The present work was undertaken to study the effects of sucrose and beef tallow on some biochemical factors such as blood lipids, glucose, immunoreactive insulin and enzymes, and on the development of arteriosclerosis including microangiopathy in the rabbits.

View full abstract