The aim of this study was to evaluate the importance of a normal ventricular activation pattern for cardiac performance. In nine mongrel dogs, atrial pacing was compared to AV synchronous pacing at three different AV delays (150, 100, and 60 ms). In six dogs, proximal septal AV synchronous pacing was compared to apical AV synchronous pacing at three different AV delays. AV synchronous pacing was performed after RF induced complete heart block. Hemodynamics were evaluated by assessment of positive and negative dP/dt, cardiac output, and left ventricular and pulmonary pressures. Atrial pacing was superior to AV synchronous pacing with respect to positive and negative dP/dt and cardiac output. This difference was present at all AV delays. Proximal septal pacing was associated with a higher positive and negative dP/dt compared to apical pacing at all AV delays. Left ventricular activation time was significantly shorter during proximal septal pacing than during apical pacing (88 +/- 4 vs 115 +/- 4 ms, P < 0.001). We conclude that atrial and proximal septal pacing improves cardiac function and shortens the ventricular activation time compared to apical AV synchronous pacing independent of the AV interval.

A salient feature of the normal sinus node activity is its prominent beat-to-beat variability, which shows self-similarity on different time scales (fractal dynamics). However, in patients with sinus node dysfunction, short-term time sinus cycles show exaggerated variability, the characteristics of which have not been analyzed. Therefore, Poincaré plots and power spectral analysis were applied to short-term variations of sinus cycles in 30 patients with and 30 patients without sinus node disease. Three patterns of behavior were observed in sick sinus patients: type 1, completely normal (n = 3); type 2, randomlike pattern in the Poincaré plots with "white noise" power spectra (n = 9); and type 3, a transitional pattern, characterized by remnants of normal behavior mixed with scattered points (n = 18). In control subjects, only type 1 (n = 27) and type 3 (n = 3) patterns were observed, P < 0.0001. The power spectral changes in sinus node dysfunction are thus characterized by a loss of the inverse power law relationship, which both has implications for heart rate variability analysis and might offer a new diagnostic approach.

This study included 30 patients (17 males and 13 females; mean age, 73.7 ± 13.1 years) who were diagnosed with dehydration based on vital signs, skin symptoms, and blood test findings by emergency medicine physicians. First, the attending physician of our department measured oral mucosal dryness. Subsequently, the emergency medicine physician blindly divided the severity of dehydration into three stages according to clinical findings and blood test results. In this study, the oral moisture‐checking device (Mucus®; Life Co., Ltd., Saitama, Japan) was used to measure the oral mucosal dryness. We examined the oral moisture level for each dehydration severity level and the correlations of each severity level of dehydration with the measured values. Spearman's correlation coefficient (Medcalc version 11.3 for Windows) was used for statistical analysis. P < 0.05 indicated significant differences. Twenty‐six patients were diagnosed with dry mouth, and a moderate negative correlation was found between the severity of dehydration and oral moisture degree ( r = −0.686). The correlation coefficient for the relationship between oral moisture degree and severity of dehydration was −0.686, indicating a negative correlation ( P < .05). These results suggest that the oral mucosal dryness may be a useful index of dehydration severity.

Chronic cobalt exposure is characterized by severe cardiac insufficiency. Since the mechanisms of cobalt toxicity are not yet clear, we analysed the effects of chronic cobalt exposure on antioxidant enzyme activities and myocardial mitochondrial ATP production rate in a rat model. One group of rats was fed a conventional diet and another a cobalt supplemented diet for 24 weeks. The manganese-superoxide dismutase activity was markedly reduced in the cobalt rats (18+/-4.7 U/mg protein) compared to the control rats (100+/-22 U/mg protein; p <0.001). Activity in the respiratory chain enzymes succinate-cytochrome c reductase, NADH-cytochrome c reductase and cytochrome c oxidase was also reduced in the cobalt rats (p<0.01). Glutamate dehydrogenase activity, located in the mitochondrial matrix, was unchanged. The mitochondrial ATP production rate in relation to myocardial mass was lower in the cobalt rats for all substrates tested except palmitoyl-l-carnitine + malate. In conclusion, 24 weeks of chronic cobalt exposure induces a marked decrease in manganese-superoxide dismutase activity, a moderate decrease in mitochondrial ATP production rate and a general reduction in the capacity of the respiratory chain. The impairment in mitochondrial ATP production might be secondary to the decreased manganese-superoxide dismutase activity, causing inactivation of mitochondrial factors susceptible to superoxide radicals.