The long-term prognosis after cardiac pacing in A-V block was assessed by a follow-up study of 59 patients in whom pacing had been introduced 4 years or more before analysis. The 1 year survival rate was 85% and the 4 year survival rate was 71%. These figures are substantially better than the survival rate reported in patients not paced. The mortality has been higher in patients older than 70 years old. Even though patients were reviewed monthly or every 3 months in a pacemaker clinic, there were 3 sudden deaths in 4 years.

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Thirty-one patients with angina pectoris and 15 patients with myocardial infarction who performed exercise test by Master's double two-step test have been longitudinally followed up for 4-10 years. Exercise electrocardiogram was taken by Frank's lead and T loop was constructed in frontal and horizontal planes from 3 scalar tracings recorded at a paper speed of 100mm/sec. ST vector was determined at 100 msec from the beginning of Q wave and the line connecting 2 ST vectors before exercise and at the point of the maximal ST change after exercise was determined as ST exercise vector. To indicate width of the T loop, the length to width ratio (L/W) was used and the change of width of the T loop in-duced by exercise was expressed by a ratio of L/W between before exercise and at the maximal change in frontal and horizontal planes. In cases having ST exercise vector of 0.1mV or more the magnitude or the direction of the ST exercise vector alone has little prognostic value and widening of the T loop in addition to the ST exercise vector of 0.1mV or more occurring after exercise was a predictive sign of poor prognosis and no widening of the T loop was a predictive sign of good prognosis.

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To clarify the genesis of the third heart sound (IIIS), phonoechocar-diographic analysis was made in 31 cases with apparent IIIS.
The mitral valve, either anterior or posterior, showed no definite movement coincided with the IIIS. At the time of IIIS, mitral valve is in the closing process, but it is still widely open, and there was no evid-ence of the stretch or tension of the valve apparatus. On the other hand, the endocardial echoes, either of interventricular septum or of posterior wall of the left ventricle, almost always showed definite check point (point of inflexion) during (or exactly at the end of) rapid ventricular filling as manifested by the sudden change in the diastolic dimension of the left ventricle near the apex. The IIIS seems likely to originate from the abruptly arrested momentum of the moving mass of blood at this check point and then the vibration of the relaxed cardiohemic system.

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Diagnostic capabilities for detection of the left atrial clot in patients with mitral stenosis were compared between echocardiography and angiocardiography. Large clots in the left atrial body were correctly diagnosed either by echocardiography or by angiocardiography. Clots in the left atrial appendage were not disclosed by echocardiography. Left atrial visualization with pulmonary arteriography offers only possible diagnosis of the clot in the appendage. Definite diagnosis of the clot in this location requires transseptal left atriography.

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Relationships between P wave abnormalities in lead II and V₁ and clinical as well as hemodynamic findings and the prognosis of 27 attacks of AMI were evaluated.
1) Patients with clinical left ventricular failure showed large negative deflections in lead V₁ compared to patients without.
2) There was a significant correlation between the magnitude of PTF-V₁ and PCW (r=-0.75, p<0.01).
3) In 20 of the 27 attacks (74%), PTF-V₁ correctly identified whether or not PCW was normal on admission.
4) Patients with frequent premature beats and any of the bundle branch blocks had a large negative deflection in V₁ compared to patients without.
5) There was a significant correlation between the magnitude of PTF-V₁ and Peel's prognostic index (r=-0.74, p<0.01). Moreover, 70% of the patients with abnormal PTF-V₁ (less than -0.03mm•sec) and elevated Peel's prognostic index (more than 12) died during hospitalization.
6) The patients who died during hospitalization had a large nega-tive deflection in lead V₁ compared to those patients who survived.
7) Patients with past history of old myocardial infarction had a larger negative deflection in lead V₁ compared to the patients without past history of old myocardial infarction.
8) There is no correlation between the duration and amplitude of P wave in lead II and PCW.
9) Thus, it is concluded that in patients with AMI, the magnitude of PTF-V₁ reflects the level of PCW and is useful as a parameter for therapy and prognosis evaluation.

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In order to investigate the relation between the infarcted area in myocardial infarction and the change of the QRS loop, the following method was tried.
The normal QRS loops in 3 planes were constructed with the digital computer. Then the vector of an optional segment corresponding to infarction was diminished and the QRS loops were constructed. The comparison of the QRS loops in clinical cases and in the construction method was made and the vectorcardiographic findings to estimate the infarcted area were discussed.

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The Korotkoff sound appearance time (QK intervals) was measured in 224 normal subjects of both sexes between the age of 6 and 79 years. The sex difference was not obvious except for the diastolic values of the intervals (QKd) in the sixth decade. Although the QK intervals remained almost unchanged between the third and the fifth decade, both the systolic (QKs) and the diastolic values were significantly smaller in the young subjects under the age of 20. On the other hand, QKs was significantly decreased and QKd and the difference between the systolic and diastolic values (QKs-d) were significantly increased in the elderly subjects. The short QK interval in the young subjects was considered to be mainly attributable to the short preejection period, while the increased pulse wave velocity was postulated to be the main responsible factor for the shortening of QKd in the elderly subjects. A statistically significant negative correlation was demonstrated between QKd and the heart rate in both sexes, while QKs and QKs-d were not significantly correlated with the heart rate.

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To attain a quantitative understanding of carotid sinus reflex control of circulation, we studied the correlation between changes in total vascular capacity (V) and total peripheral resistance (R). We used a newly devised, accurate and simple method to measure changes in V while both mean central venous and arterial pressures being kept constant. In 7 open chest dogs (7-11Kg, mean 8.9Kg), bilateral carotid occlusion after vagotomy reduced V by as much as 58±9 (SE)ml or approximately 8% of total blood volume while R increased by 36±5% from 0.08±0.01mmHg.min/ml. Similar responses were obtained either in the reflex before vagotomy or with infusion of norepinephrine. Mathematical analysis with Poiseuille's law suggested that internal radius of an average resistance vessel decreased approximately 1.5 to 3 times as much as that of an average capacitance vessel. The wall to lumen ratio of the average resistance vessel estimated from the correlation was 0.3 to 0.6, being within physiological range. Therefore, the difference in vascular sensitivity may be partly owing to the wall to lumen ratio of resistance vessels. Moreover, the correlative changes in the capacitance and resistance vessels were elucidated to be significantly responsible for the characteristic hemodynamic changes in carotid sinus reflex.

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The effects of various concentrations (0, 0.5, 1, 2, 4, and 8mM) of potassium chloride on the simultaneously recorded action potential and contractility; and Mg⁺⁺-dependent, Na⁺⁺-K⁺-stimulated membrane ATPase of guinea pig's heart were studied. In KCl-free solution, the inhibition of the Na⁺-K⁺-ATPase was associated both with a shortening of the duration of action potential and an increase in the contractility.There was a decrease in the overshoot of action potential and an increase in the resting potential. Potassium chloride produced a concentration dependent lengthening of the action potential duration; decrease in the contraction and resting potential; and an increase in the overshoot of action potential and Na⁺-K⁺-ATPase activity. The changes in the action potential and contraction were associated with the changes in the Na⁺-K⁺-ATPase activity. The changes in the ATPase activity preceded the changes in the action potential and contractility. The involvement of ATPase in the genesis of the resting potential; overshoot and duration of action potential; and contraction has been discussed.

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Intracisternal injections of veratrine in the anesthetized dog were used to study the effects of extreme sympathetic stimulation on left ventricular diastolic compliance. The results obtained were compared with those seen during volume expansion with whole blood, and after removal of both stellate ganglia. The injection of veratrine into the cisterna magna caused an increase in left ventricular end-diastolic pressure (LVEDP) which was considerably larger than that which occurred in left ventricular end-diastolic circumferential (LVEDC) segment length suggesting a reduction in diastolic compliance. There were also increases in left ventricular systolic pressure (LVSP) as well as its first derivative (LV dp/dt). Bilateral stellectomy during the veratrine response abruptly reduced LVEDP with a lesser decrease in LVEDC. Thus, the left ventricular compliance change was reversed. Both LVSP and LV dp/dt were decreased by stellectomy but remained above control levels. During transfusion, the pressure-length curve of the ventricle was located down-ward and to the right in comparison with the curve observed with intracisternal veratrine.

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Pathological studies using routine pathological technics, microangiography and electron microscopy were performed on the 28 goats with an artificial heart (including 2 goats which survived for 30 and 37 days).
In this paper, the brain, natural heart, and lungs of the goats were discussed.
No special findings were seen in the brain except for rare infarcted areas. The natural heart almost always showed infarction-like lesions in the subendocardium and myocardium at the cut surface. The longer the animal survive, these findings became the more serious. The light microscopic findings on the lungs were classified into 6 groups. The most important findings of them are massive, diffuse exsudation with hemorrhage and its changes to chronic status. The main pathophysiological status, causing the pulmonary lesions, seemed to be peripheral circulatory insufficiency with increased permeability of peripheral vessels, especially of venulae. Thrombi were detected more frequently in the kidneys and lungs than in any other organs. The vascular walls where the thrombi were attached to, were often seen to be damaged, so that almost all thrombi were thought to be formed in the local vessels in situ, but not in the artificial heart.
The main clinical causes to the pulmonary insufficiency were thought to be surgical operation including anesthesia, functional incompleteness of the artificial heart, etc.

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Spontaneous action potential (AP) discharge could be induced by an application of long (5-10 sec) depolarizing currents in 68% of canine ventricular myocardium tested in the voltage range between about -65 and-10mV. The constant currents of various intensities were applied across a sucrose gap, and intracellular potentials were recorded with a microelectrode. The firing rate of the AP's was voltagedependent and ranged between 0.7 and 2.5Hz. The AP was dependent on both [Ca⁺⁺]₀ and [Na⁺]₀. Increase of [Na⁺]₀ from 37 to 149mM increased the firing rate, maximum rate of rise, and overshoot of the AP's while increase of [Ca⁺⁺]₀ from 0.45mM to 1.8 and 7.2mM increased the firing rate and maximum rate of rise, but did not change the amplitude of overshoot. AP discharges were not blocked by tetrodotoxin (10^-5Gm/ml), but were effectively blocked by verapamil (6×10^-6Gm/ml). Adrenaline (5×10^-6Gm/ml) initiated AP's in otherwise quiescent preparations. The results suggest that spontaneous AP's may be produced by inflowing of slow Na⁺ and Ca⁺⁺ currents modified by underlying change of K⁺-permeability. Possible clinical significance of this phenomenon is discussed in relation to ventricular arrhythmia.

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The fourth case found in Japan manifesting the features of malignant hypertension and microangiopathic hemolytic anemia (MHA) was reported. In this case, bilateral nephrectomy brought down the blood pressure and relieved MHA. The patient has since been maintained alive and well on hemodialysis up to the time of this report.

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A case of aortic atresia associated with right aortic arch is described. This is the second case in the literature. The diagnosis of aortic atresia was made prior to death by right heart catheterization with angiocardiography and this was confirmed at autopsy. The necessity of an early and accurate diagnosis of this disease is discussed for providing more opportunity of surgical treatment.

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A case of tumor embolism of the coronary artery in a 78-year-old woman was presented. The tumor embolus originating from cancer of the breast resulted in massive large myocardial infarction in the lateral wall of the left ventricle, and she died of cardiac rupture. Metastatic lesions were found in the bilateral lungs, the endocardial and subendocardial layers of the left ventricle, with a growth of tumor thrombus into the left atrium, and also other extracardiac organs.

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