title: Relationship between left ventricular pressure and the calibrated apexcardiogram during abrupt outflow obstruction.
abstract: In order to study the influence of sudden left ventricular pressure rise on the calibrated apexcardiogram, 181 acute aortic occlusions were performed during systole in 7 dog experiments. For each beat preceding (CO) an occlusion and each occlusion (OC), peak systolic amplitude of left ventricular pressure (CO: 118.5 +/- 17.8 mm Hg; OC: 205.8 +/- 38.7 mm Hg) and apexcardiogram (CO: 48.8 +/- 16.7 mm Hg; OC: 63.0 +/- 25.8 mm Hg) were measured. Pressure gradients, ratios and surface areas of all tracings were digitally calculated. The cross-correlation function between pressure and apexcardiogram was also calculated in order to determine time lags. Significant correlations were found: between surface ratios and pressure gradient of pressure (r = 0.80, p less than 0.001) and of apexcardiogram (r = 0.79, p less than 0.001); between surface ratios of pressure and surface of apexcardiogram (r = 0.52, p less than 0.001). The data suggest that during isovolumic systole, the time integral of the left ventricular pressure and its change during the ejection phase define to a large extent the general shape and size of the apexcardiogram.
mesh_terms: D000818:Animals; D001011:Aorta / Q000473:pathology*; D003251:Constriction, Pathologic; D004285:Dogs; D007702:Kinetocardiography; D009200:Myocardial Contraction; D013318:Stroke Volume; D016276:Ventricular Function