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Diastolic mitral regurgitation in patients with atrioventricular conduction abnormalities: a common finding by
Insights
Atrioventricular (AV) block can cause diastolic mitral regurgitation, particularly in first-degree AV block. Echocardiography revealed this regurgitation is linked to P wave timing during diastole.
Area of Science:
- Cardiology
- Echocardiography
- Electrophysiology
Background:
- Atrioventricular (AV) block affects cardiac conduction.
- The relationship between AV block and diastolic mitral regurgitation is not fully understood.
- Echocardiography is a key tool for assessing cardiac function.
Purpose of the Study:
- To investigate the presence and characteristics of diastolic mitral regurgitation in patients with varying degrees of AV block.
- To correlate echocardiographic findings with PR interval duration and P wave timing in diastole.
Main Methods:
- M-mode and Doppler echocardiography were performed on 16 patients with first-degree AV block, 4 with advanced AV block, and 20 controls.
- Measurements included P wave to mitral valve closure time (M-mode) and P wave to end of mitral flow (Doppler).
- Pulsed-wave Doppler was used to detect diastolic mitral regurgitation.
Main Results:
- No significant difference in P wave to mitral valve closure/flow times between controls and first-degree AV block patients.
- Late diastolic mitral regurgitation was detected in 56% of first-degree AV block patients, but none of the controls.
- In advanced AV block, mitral regurgitation varied with P wave timing; regurgitation occurred with early diastolic P waves, while P waves in systole led to no forward flow or regurgitation.
Conclusions:
- First-degree AV block is associated with a higher incidence of late diastolic mitral regurgitation.
- Diastolic mitral regurgitation in AV block is dependent on the timing of atrial contraction (P wave) relative to ventricular filling.
- Echocardiography can identify this specific type of mitral regurgitation, highlighting potential functional consequences of conduction delays.
Abstract:
M-mode and Doppler echocardiography were performed in 16 patients with first degree atrioventricular (AV) block, 1 patient with second degree (Wenckebach type) and 3 patients with third degree AV block; 20 individuals with a normal 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 mitral 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 on 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 followed 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 regurgitation detected by Doppler technique.(ABSTRACT TRUNCATED AT 250 WORDS)