Author + information
- Received September 24, 1985
- Revision received November 13, 1985
- Accepted November 26, 1985
- Published online April 1, 1986.
- Ioannis P. Panidis, MD, FACCa,
- John Ross, RCPT,
- Brian Munley, MD,
- Pasquale Nestico, MD and
- Gary S. Mintz, MD, FACC
- ↵aAddress for reprints: Ioannis P, Panidis, MD, Cardiac Ultrasound Laboratory, Hahnemann University Hospital, 230 North Broad Street, MS313, Philadelphia, Pennsylvania 19102-1192.
M-mode and Doppler echocardiography were performed in 16 patients with first degree atrioventricular (AV) block, 1 patient with second degree (Werickebach type) and 3 patierits with third degree AVblock; 20 individuals with a hormal PR interval served as control subjects. The time from the onset of the P wave to the mitral valve closure by M-mode and to the end of mitral flow by Doppler echocardiography were obtained. In 20 normal subjects, the P wave to niitral valve closure interval measured 220 ± 30 ms by M-mode and to the end of mitral flow 225 ± 29 ms by Doppler technique (p = NS). In patients with first degree AV block, these intervals measured 242 ± 41 and 249 ± 36 ms, respectively (p = NS).
Late diastolic (before the onset of the QRS complex) mitral regurgitation was detected by pulsed mode Doppler imaging in 9 (56%) of the 16 patients with first degree AV block but in none with a normal PR interval. In the four patients with advanced AV block, intermittent mid or late diastolic mitral regurgitation was found to depend oil the position of the P wave in diastole. With early diastolic P waves, the end of mitral valve flow by DOppler technique occurred 230 to 250 ms after the onset of the P wave and was foliowed by mild diastolic mitral regurgitation of variable duration. With P waves falling in systole, the mitral valve remained open throughout diastole; during most of diastole, however, there was neither forward mitral flow (diastasis) nor diastolic mitral regurgitatioh detected by Doppler technique. Forward aortic flow velocities by Doppler recording were not different in cardiac cycles with or without diastolic mitral regurgitation.
It is concluded that prolongation of the PR interval can result in development of a left ventricular-left atrial pressure gradient in diastole induced by the atrial contraction and premature mitial valve closure, which. is probably incomplete and is often associated with diastolic mitral regurgitation of no apparent hemodynamic significance.
- Received September 24, 1985.
- Revision received November 13, 1985.
- Accepted November 26, 1985.
- American College of Cardiology Foundation