A follow-up study on pacemaker function in 15 patients with implanted cardiac pacemaker has been performed by telphone transmission. The transmitting set consisting of electrocardiograph, pacemaker pulse modulator and acoustic coupler was manipulated by the patients themselves. ECG, pacemaker pulse, and pulse rate were simultaneously transmitted through 1 channel to the receiver in our clinic. Of 56 patients with pacemaker, 15 patients were surveyed by telephone transmission. In these patients battery exhaustion was detected in 3, competition in 2, and lead fracture in 1.The fact that surveillance and follow-up of the patients with implanted cardiac pacemaker could be carried out by telephone transmission as well as by clinic visitation tells us that the telephone transmission is a useful method and plays an important role in a pacemaker clinic. Moreover our study established its further usefulness in the patient's preference due to difficulties in travelling to the pacemaker clinic and in reducing patient's anxiety.

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The mechanism of the irregularity of R-R intervals and especially the genesis of the long R-R intervals in atrial fibrillation were clarified. From the point of view of the present study, the sequence of successive R-R intervals can be regarded as a stochastic process, and consequently mathematical analyses can be applied, and the following conclusion could be obtained: the stability of the data, mathematically called stationarity, is present in the sequence of R-R intervals, and these intervals are independently and identically distributed. The probability density function is an Erlangian distribution with phase k of 20 to 26. Namely, as soon as, on the average, 20 to 26 atrial excitatory stimuli have arrived at the AV node, a threshold value of the AV node is reached and ventricular activation is induced. However, if we examine the mathematical structure of the sequence of successive R-R intervals in more detail, the following results can be evidently obtained: during atrial fibrillation with rapid ventricular response, the sequence of R-R intervals is completely independent, but with intermediate or slow ventricular response the adjacent R-R intervals correclate with each other and these adjacent intervals have at least the first order Markov property, which seems to be caused by the concealed conduction. Because of this Markov property due to the prolongation of the refractory period of the AV node, slow ventricular response results.

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In order to investigate the mechanism of the "exaggerated na-triuresis" in hypertension, 300ml of 3% saline was infused for 1 hour during hydropenia in 13 patients with normal renin essential hypertension and 5 normotensive subjects on a daily ingestion of 4 Gm and 16 Gm of NaCl. At the end of the infusion, the circulating blood volume indicated by the change in serum total protein concentration and the glomerular filtered load were increased in a similar manner in both groups.
Prompt and enhanced natriuresis and diuresis were seen within 1-2 hours after starting the infusion in the hypertensives on a daily ingestion of 16 Gm of NaCl. Significant positive correlations were found between the change in mean arterial blood pressure (ΔMAP) and UV, and between ΔMAP and U_NaV in the hypertensives either on a daily 4 Gm or 16 Gm ingestion of NaCl. Free water reabsorption (T^c_H2O) was lower in the hypertensives than that in the controls at high levels of osmolar clearance (C_osm). Plasma renin activity (PRA) did not differ in either group on either NaCl ingestion and was equally suppressed on a daily ingestion of 4 Gm of NaCl, while little changed on a high salt intake. Plasma aldosterone levels changed in parallel with PRA.
It is suggested that the "exaggerated natriuresis" is due to the decreased tubular sodium reabsorption, which may be the result of intrarenal hemodynamic changes related to the elevated renal perfusion pressure. The decreased medullary osmolar gradient probably induced by an increase in the medullary blood flow is a possible contributing factor in the enhanced sodium and water excretion, and the reninaldosterone system does not seem to play an important role.

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Direct membrane effects and beta-adrenergic blocking action of pindolol were studied comparatively on isolated perfused cardiac fibers of dogs. In Purkinje fibers, the duration of transmembrane action potential decreased in concentrations higher than 0.5mg/L. Maximum rate of depolarization also decreased in higher concentrations (5.0mg/L or more). The functional refractory period decreased to a lesser degree compared with the decrease of the action potential duration. Nevertheless, slowrising action potentials could not be abolished in premature responses, probably because of membrane depressant effects, of this drug. In ventricular muscle fibers, these changes were minimum in the same range of concentrations. On the other hand, 0.05mg/L of pindolol which was close to the therapeutic plasma concentrations and had no effect on action potentials of both Purkinje and ventricular muscle fibers, minimized the increase in automaticity of Purkinje fibers induced by 0.2mg/L of isoproterenol. It is rationally speculated that the mechanism of antiarrhthmic action of pindolol is mainly due to its beta-adrenergic blocking action.

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Using isolated, blood-perfused canine atrial preparations the effects of ouabain on sinus rate and contraction were investigated in 20 preparations. A continuous infusion of ouabain (1μg/min) usually induced a significant increase in sinus rate but occasionally a slight but no significant decrease followed by a clear increase, and then finally decrease followed by atrial arrest. On the inotropy, ouabain induced only distinct positive inotropic effect from the earlier stage, and the time to the maximum positive inotropic effect was much earlier than that to the maximum chronotropic effect.
The positive chronotropic effect of norepinephrine was not affected by ouabain in the dose for inducing marked positive inotropic effect. On the other hand, the positive inotropic effect of norepinephrine was suppressed in percent changes by ouabain but not abolished.
The negative chronotropic and inotropic effects of ACh were not significantly affected by ouabain in the dose for inducing marked positive inotropic effect.
During atrial arrest by ouabain infusion, distinct staircase phenomenon disappeared. In this condition, atrial muscle responded more readily to higher freqencies of electric pacing (above 2Hz) than to lower frequencies (under 1Hz).

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The F₁ hybrids (F₁ ) of spontaneously hypertensive rats (SHR) and Wistar rats (W), whose kidneys were transplanted from SHR at the age of 10 weeks and 20 weeks, showed significant elevation of blood pressure (BP) for 11 weeks after the transplantation. In F₁ with W or F₁ kidneys BP was decreased near to the normal level. F₁ whose kidneys were transplanted from SHR or W showed low renin activity both in plasma and the kidney. It is suggested that BP of SHR is probably determined by the renal pro-hypertensive factor(s) other than renin influencing on sympathetic nerves through central nervous systems.

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Ligation of the main femoral artery is followed by a rapid development of collateral arteries. To detect an increase in vascular permeability of the collateral arteries, colloidal carbon (1ml/Kg, iv) was injected into 153 rabbits at various times after ligation or sham-ligation of the main femoral artery. These animals were killed later and collateral arteries was dissected. Increase in vascular permeability was identified by the presence of visible carbon deposits on the vascular walls. The carbon deposits were frequently found on the intermediate segments of the collateral system in legs with ligation, but were not found on any arteries either in legs with sham-ligation or in contralateral untouched legs. The increase in vascular permeability was observed in 15 of 17 animals as early as 6 hours, in 32 of 36 animals 1 day but only in 5 of 21 animals 6 to 8 days after ligation. The arterial segments with carbon deposits showed various structural changes such as fragmentation of the internal elastic layer, degeneration of the medial muscle and deposition of fibrinoid material. These results indicate that vascular permeability transiently increases in the intermediate segments of developing collateral arteries. Acute vasodilatation may be responsible for the increase in vascular permeability.

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The effects of coronary vasodilating agents and alpha- and beta-adrenergic blocking agents on cyclical reductions of blood flow in the partially constricted coronary artery of anesthetized dogs were examined. Intravenous injections of nitroglycerin (50μg/Kg), SG 75 (150μg/Kg), papaverine (1mg/Kg), and nicotinic acid (10mg/Kg) eliminated both cyclical reductions of flow and ST elevation (group 1). Nifedipine (10μg/Kg), verapamil (500μg/Kg), diltiazem (500μg/Kg), and propranolol (500μg/Kg) suppressed ST elevation, but they could not eliminate cyclical reductions of flow (group 2). Dipyridamole (1mg/Kg) and phentolamine (500μg/Kg) augmented both ST elevation and cyclical reductions of flow (group 3). The results indicate that ST elevation due to cyclical reductions of coronary blood flow was eliminated by spasmolytic actions of group 1 on coronary artery, was suppressed by negative chronotropic and/ or inotropic actions of group 2, and was augmented by peripheral actions of group 3.

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The effect of verapamil on the isoproterenol(ISO)-induced transmural metabolic lesion in the left ventricular wall was investigated in the rat heart. The treatment with ISO 2.5mg/Kg s.c. on 2 consecutive days resulted in significant decreases of creatine phosphate in the subendocardium(ENDO) and of adenosine triphosphate in the ENDO and the subepicardium. On the other hand, inorganic phosphate(Pi) and lactate (LA) were increased in both layers. These changes were more prominent in the ENDO. Pretreatment with verapamil 25mg/Kg s.c. prevented the reduction of high energy phosphate compounds and the increases of Pi and LA in both layers by ISO.

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Prolongation of P-Q interval in the anesthetized rat was observed by repeated injection of killed group A streptococci. The prolongation was clearly recognized at about the 11th week after the first injection, but afterwards P-Q interval recovered to the normal level in spite of continuous injection of killed streptococci. His bundle electrogram recorded from isolated heart revealed the prolongation of A-H interval in the treated rat. Moreover, the transmembrane action potential in the atrioventricular nodal region of treated rat was slightly deteriorated, but the action potentials in the other cardiac muscles were not changed. It was deduced from the above results that P-Q prolongation was transiently brought about by the injection of killed group A streptococci and that deterioration of muscle in the atrioventricular nodal region might take a main part in the P-Q prolongation.

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The effects of nitroprusside (NP), phentolamine (PH), and nitroglycerin (NTG) were studied on systemic hemodynamics, regional contraction and epicardial ST segment in the border and non-ischemic zones of the left ventricle of anesthetized open chest dogs. The anterior descending coronary artery (LAD) was completely occluded. NP (5μg/Kg/min) or PH (100μg/Kg/min) was drip-infused, or a bolus injection of NTG (20μg/Kg) was administered intravenously. The 3 vasodilator agents produced somewhat similar reductions in systemic arterial pressure. However, NP caused a greater reduction in total peripheral resistance (TPR) than in left ventricular end-diastolic pressure (LVEDP), and caused a decline, in the ischemic marginal zone, in both ST segment eievation and paradoxical systolic lengthening. PH decreased TPR without reducing LVEDP and elevated the ST segment. NTG markedly reduced LVEDP and TPR slightly. NTG improved the elevated ST segment and paradoxical systolic expansion of the segmental myocardium in the border zone. Cardiac output rose with NP and PH, whereas injected NTG caused a reduction in cardiac output. These findings suggest that NP favourably affects the ischemic myocardium mainly by reducing the afterload and that the NTG-induced improvement of myocardial ischemia can be attributed mainly to preload reduction, while PH enhances cardiac function with slight or no improvement of myocardial ischemia in the border zone.

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The concomitant use of INTRA-AORTIC BALLOON PUMPING (IABP) and venoarterial bypass(VAB) without oxygenation (VAB_??_O) was performed in 10 experiments using 6 dogs in cardiogenic shock. VAB_??_O was accomplished with the cricuit from the right atrium to the femoral artery and bypass flow rates were set at approximately one third of the baseline cardiac output. Displacement volume of the IABP balloon was 10 or 20ml.
Evaluation of hemodynamic effects of the concomitant use was carried out, as compared with the single use of IABP or VAB_??_O.
The following findings were obtained:
(1) In the concomitant use, left ventricular afterload decreased, while mean aortic root pressure increased. Increase in total perfusion flow, decrease in mean left atrial pressure and decrease in left ventricular stroke work were shown more effective than each of the single uses.
(2) These results suggest that the concomitant use of IABP and VABsO can be used as a second step assisted circulation when IABP is shown uneffective in the case of severe cardiogenic shock.

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Two cases are reported of a 30-year-old and of a 28-year-old Japanese women with primary aldosteronism in whom metabolic and blood pressure abnormalities were aggravated during peripartum period. The characteristic findings in 2 present cases are as follows; 1) lower blood pressure during pregnancy, 2) elevated blood pressure during peripartum period, and 3) after parturition, serum potassium decreased, and the blood pressure elevated. The reason why the hypertension and hypokalemia associated with primary aldosteronism were ameliorated during pregnancy was thought to be due to the increased secretion of progesterone. Furthermore, the rapid recurrence of symptoms, increase in blood pressure, and hypokalemia in the post-partum period could be related to elevated prolactin and decreased progesterone levels.

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A rare case of sinus of Valsalva aneurysm ruptured into the left ventricle was reported. The echocardiogram was suggestive of the diagnosis. The abnormal echo extended from the aortic root to the left ventricular cavity in diastole and disappeared in systole. Discussion was made on the etiology and differential diagnosis.

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