Doppler echocardiographic assessment of the effect of varying atrioventricular delay and pacemaker mode on left ventricular filling Pulsed Doppler echocardiography was used to study the timing and dynamics of left ventricular filling in 14 patients with permanent dual-chamber programmable pacemakers. Pacemakers were programmed to atrial sensed (VDD) mode and atrial-ventricular sequential paced mode at low (DVI-L) and high (DVI-H) heart rates, and pulsed Doppler recordings of transmitral flow were analyzed at atrioventricular delays of 50 to 300 msec in each mode. There was a significant decrease in the one-third filling fraction in both VDD and DVI-L modes and a significant increase in WI-H modes with increasing atrioventricular delay. The ratio of early filling area to atrial filling area was significantly lower at longer atrioventricular delays in both VDD and DVI-L modes. The time from pacemaker spike to mitral valve closure was highly significantly correlated with atrioventricular delay in VDD, DVI-L, and DVI-H modes (r = -0.92, p = 0.0001; r = -0.90, p = 0.0001; and r = -0.85, p = 0.0001, r espectively) as was the diastolic filling time to a lesser extent (r = -0.73, p = 0.0001; f = -0.89, p = 0.0001; r = -0.61, p = 0.0001, respectively). Events reflecting atrial systole occurred at a later time in the cardiac cycle in the atrial paced vs the atrial sensed mode. Thus changes in atrioventricular delay and pacemaker mode in this group of patients are a strong determinant of the timing and dynamics of left ventricular filling. (AM HEART d 1988;115:611) Anthony C. Pearson, M.D., Denise L. Janosik, M.D., Robert R. Redd, M.D., Thomas A. Buckingham, M.D., Richard I. Blum, M.D., and Arthur J. Labovitz, M.D., St. Louis, MO., with the technical assistance of Denise Mrosek Measurement of left ventricular filling has long been recognized as a valuable tool in the evaluation of left ventricular diastolic function.1*2 Although diastolic left ventricular filling is determined by a complex interaction of dynamic and passive properties of both the atria and ventricles,3’4 it can be measured directly and is not derived from complex mathemat- ic formulas. In addition, although it was initially measured by contrast angiography,1+2,5 it can now be measured by several different noninvasive methods including radionuclide ventriculography,6-R M- modeg-l2 and two-dimensionall echocardiography, and, most recently, pulsed Doppler echocardiogra- phy.14,15 Using such techniques investigators have been able to demonstrate abnormalities of left ven- tricular filling as an early finding in hypertension, and coronary artery disease.‘, 6, 8, lo From the Department of Internal Medicine, Division of Cardiology, St. Louis University Medical Center. Received for publication July 23, 1987; accepted Nov. 5, 1987. Reprint requests: Anthony C. Pearson, M.D., St. Louis University Hospi- tal, 1325 S. Grand Blvd., St. Louis, MO 63104. Although heart rate is a known determinant of left ventricular filling, l6 the effect of varying atrioven- tricular delay (AVD) is not as well defined. In addition, the effect of a paced vs a sensed atria1 contraction on left ventricular filling is not known. In order to clarify these issues we examined patients with permanent programmable dual-chamber pace- makers using pulsed Doppler echocardiographic assessment of left ventricular inflow. Because the relative timing and the rate of atria1 and ventricular contraction can be manipulated by reprogramming the pacemaker, these patients provid.e an ideal opportunity for such a study. METHODS The study group consisted of 14 patients who had had permanent dual-chamber pacemakers implanted. The patient’s age, underlying rhythm, pacemaker type, and reason for implantation are listed in Table I. There were seven men and seven women. Eight patients had underly- ing complete heart block, and six were in sinus rhythm. This was a heterogeneous group of patients with the following cardiac diagnoses confirmed by two-dimensional echocardiography: Seven had normal left ventricular func- 611