Two-dimensional echocardiography is useful for demonstrating abnormal contractility of human left ventricular papillary muscles. Papillary muscle contractility should be analyzed in each case to elucidate the mechanism of mitral regurgitation in patients with papillary muscle dysfunction.

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This study was carried out in order to estimate the risk of habu snake bite on the Amami Islands in relation to meteorological and human behavioural factors. A time-series analysis of the seasonal variation of habu snake bite was also carried out in order to clarify the possible mechanism of the epidemiological features of habu bite. It was found that the risk of habu bite has been decreasing over a long period of time on both the islands of Amamioshima and Tokunoshima. In general, the risk is higher on Tokunoshima for males and on Amamioshima it is higher for females. There was a significant positive correlation between risk and time spent in the sugar cane fields. Analysis of annual cumulative risk revealed that the inhabitants of Tokunoshima were more likely to be bitten by the habu than those of Amamioshima. The probable explanation for this was the difference between the two islands in the size of cultivated area or the proportion of the labour force engaged in primary industry. Seasonal variation of habu bite showed a maximum occurrence in June. This seasonality was probably caused by the effects of climate on the activities of both humans and habu snakes. Meteorological conditions were investigated by multiple regression analysis for causal effects on the seasonal variation in the occurrence of habu bite; as a result, temperature and humidity were presumed to have an important influence. These facts supplied the most probable explanation for the highest incidence of habu bite being in June rather than in August--the hottest season--on the Amami Islands.

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We investigated whether the left ventricular filling profile, defined as the early to late diastolic left ventricular filling volume ratio, during the preceding control beats actually affects the pulse pressure during a ventricular premature contraction (PVC). Twenty patients underwent invasive electrophysiological study for sinus bradycardia. VPCs with various coupling intervals were induced by right ventricular electrical stimulation, and the mitral filling flow velocity by pulsed Doppler echocardiography, the femoral arterial pressure curve and the electrocardiogram were simultaneously recorded. The early to late diastolic velocity-time integral ratio (Ei/Ai ratio) of the mitral filling flow velocity during the control beats which preceded the VPC was measured as an index characterizing left ventricular filling profile. The coupling interval of each VPC and the extrasystolic beat pulse pressure were measured. The ratio of the extrasystolic beat pulse pressure to the control beat pulse pressure was expressed in % (% extrasystolic beat pulse pressure). The correlation between the coupling interval and the % extrasystolic beat pulse pressure was investigated. Coupling intervals of 0.80, 0.70, 0.60, 0.50, and 0.45 s were used. At a coupling interval of 0.80 or 0.45 s, the % extrasystolic beat pulse pressure showed no significant correlation with the Ei/Ai ratio. In contrast, the % extrasystolic beat pulse pressure with coupling intervals of 0.70, 0.60, and 0.50 s showed a significant positive correlation with the Ei/Ai ratio (r = 0.67, 0.74, and 0.66, P < 0.01, respectively). In addition to the prematurity and the site of origin of the VPCs, the left ventricular filling profile during the preceding control beats may significantly affect the height of the pulse pressure during extrasystoles with medium length coupling intervals.