SUMMARY Left atrial function was evaluated in patients with and without remote myocardial infarction. The simultaneous left atrial pressure recording and left atrial and left ventricular cineangiograms were obtained with a catheter-tip micromanometer. The pressure-volume curve of the left atrium was composed of an A-loop and a V-loop. The ratio of active atrial emptying to left ventricular stroke volume in patients with myocardial infarction was significantly larger than that in normal subjects (42 + 12% vs 29 + 10%, p < 0.05). The left atrial work was also significantly greater in patients with myocardial infarction (1690 + 717 mm Hgml) than in normal subjects (940 426 mm Hg-ml, p < 0.05). The ratio of active atrial emptying to left ventricular stroke volume and left atrial work were significantly related in both normal subjects and patients with myocardial infarction (y = 0.72, p < 0.01). The left ventricular ejection fraction correlated inversely with left atrial work (y = -0.5, p < 0.05). Left atrial work also showed a significant linear correlation with left atrial volume before active atrial emptying (y = 0.82, p < 0.01).We conclude that the left atrial contribution to left ventricular function is increased in patients with remote myocardial infarction. This left atrial contribution to the left ventricle is attributed to the FrankStarling mechanism in the left atrium.LEFT ATRIAL function and its hemodynamic importance for overall cardiac performance have been discussed.' 1-3 The left atrium may serve as a conduit for the passage of blood from the pulmonary veins to the left ventricle during early left ventricular filling, as a reservoir for storing blood during left ventricular systole, and as a contractile chamber for augmentation of left ventricular filling. Understanding each of these functions and the contribution of the left atrium to left ventricular function in normal and diseased hearts is important.In this report, we analyze left atrial pressure-volume relationships in patients with remote myocardial infarction and discuss the importance of left atrial function. MethodsData were obtained during diagnostic cardiac catheterization in two groups of patients. The normal group consisted of eight patients who had no coronary, valvular or congenital heart disease and were hemodynamically normal. These patients were referred for diagnostic cardiac catheterization to evaluate chest pain. The myocardial infarction group consisted of 10 patients who had a documented remote transmural myocardial infarction, and no other associated heart disease. The clinical data for each patient are listed in medications were discontinued for at least 2 days before the study, except for sublingual nitroglycerin, which was allowed for anginal attack, but withheld 12 hours before the study. A Millar catheter-tip micromanometer (Model PC-484A, pigtail) was used for pressure measurement and cineangiography. The transducer was calibrated electronically against mercury at the beginning of each study. The zero shift during the proc...

Control data were assigned a value of 100 in order to compensate for individual differences between animals with respect to the size and shape of the chest and body, elastic factors, and thoracic transmission characteristics.

The present study aims to identify the effects of systematic walking on exercise energy expenditure (EEE) and blood profiles in middle-aged women. Fifty-two female nurse managers, aged 32 to 57 years (42.0 +/- 6.2), were randomly assigned to an intervention group (IG) and a control group (CG) for a 12-week study of the walking program. EEE was measured using a microelectronic device. Blood profiles were assessed before and after the walking program. The mean EEE (kcal/kg/d) in the IG and CG was 4.73 +/- 1.02 and 3.88 +/- 0.81 (P = 0.01), indicating an increase of 1.17 +/- 0.98 and 0.46 +/- 0.68 from baseline (P = 0.01), respectively. The mean change in high-density lipoprotein cholesterol in the IG and CG was 1.8 +/- 8.3 mg/dL and -2.9 +/- 7.0 mg/dL (P = 0.051); that in insulin was -4.5 +/- 7.5 microU/dL and -0.6 +/- 4.3 microU/dL (P = 0.046), respectively. These results show that systematic walking increases EEE and improves blood profiles.

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Relations between left atrial contraction and left atrial early filling were studied in eight subjects with atypical chest pain from simultaneous left atrial pressure recordings and left atrial cineangiograms. The left atrial ejection phase was defined as the interval from the onset of the sharp systolic rise in left atrial pressure (a point) to the point of minimum left atrial volume (Vmin). The left atrial filling phase was divided into (a) the early filling phase, the period from Vmin to the nadir of left atrial pressure (x), and (b) the late filling phase, the period from x to the point of maximum left atrial volume (Vmax). During the early filling phase, when the left atrium filled as left atrial pressure diminished, approximately 37% of total atrial filling took place. There was a direct relation between left atrial volume measured at a and x points (r = 0.91, p less than 0.01). The extension fraction, measured as the ratio of filling volume during the early filling phase to minimum left atrial volume, was significantly correlated with ejection fraction, measured as the ratio of ejected volume (delta V) during ejection phase to left atrial volume at the a point (r = 0.97, r = 0.01). Both mean and peak filling rates of left atrial volume change during the early filling phase were directly proportional to the ejected volume, the ejection fraction, and the mean ejection rate of left atrial volume change during the ejection phase. Thus these results suggest that there is close interaction between left atrial contraction and left atrial early filling.