Postextrasystolic Ventricular Pressure Responses

The peak postextrasystolic ventricular pressure was examined in tracings obtained during routine catheterization of the right and left ventricles in 252 cases. The invariable response in the apparently "normal" left ventricle was a fall or no change in peak systolic pressure, whereas in the obstructed left ventricle, the failed left ventricle, the severely volume-overloaded left ventricle, and in mitral stenosis the more usual pattern was a rise in postextrasystolic ventricular pressure. On the right side the usual response both in the normal and abnormal was a rise in postextrasystolic pressures. Significant exceptions were found when the right ventricle ejected against the aortic impedance and in constrictive pericarditis. In the intact circulation the outflow impedance and its rate of decline during the compensatory pause would appear to be the major determinant of the postextrasystolic pressure response. There is some evidence that alterations in the extent and time course of ventricular filling may be a factor, but the effects of variations in the degree of postextrasystolic potentiation based on variations in the prematurity of the extrasystole, which can so easily be demonstrated under controlled conditions, appear to be largely obscured except when fixed outflow obstruction is present. The only practical value of this observation may be the ability to recognize an "abnormal" left ventricle when the postextrasystolic beat shows a higher peak ventricular pressure and to recognize a right ventricle in free communication with the aorta when the peak right ventricular postextrasystolic pressure fails to rise. Conversely, a lower peak left ventricular systolic pressure following a premature beat should not be misinterpreted as being due to a failure of postextrasystolic potentiation and augmentation, as it is in fact a normal phenomenon.