Observations on the Relation Between Ventricular Activation Sequence and the Hemodynamic State

Hemodynamic parameters including records of left and right ventricular pressure, aortic pressure, the first derivative of the left ventricular pressure curve, and carotid flow were recorded with different patterns of ventricular activation. Special measures were used to achieve a comparable role of the atrium in ventricular filling with the different ventricular activation patterns. With an intact cardiac conduction system, definite but small differences in the hemodynamic parameters named were associated with different activation patterns. Normal ventricular activation produced slightly higher peak pressures in both ventricles and higher carotid flow than did abnormal activation. Each different activation pattern was associated with differences in the detailed shape of the ventricular pressure curves and with differences in the relative time of onset of pressure rise in right and left ventricles. When the specialized conduction system was blocked with large doses of ouabain, various patterns of ventricular activation were associated with marked differences of the hemodynamic parameters named. These findings may explain previously published conflicting results. They also suggest that disease of the conduction system may have a significant functional role in cardiac disease.