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Effect of heart rate on left ventricular diastolic transmitral flow velocity patterns assessed by Doppler
M R Harrison1, G D Clifton, A T Pennell
1Division of Cardiology, College of Medicine, University of Kentucky, Lexington 40536-0084.
Insights
This study found that increasing heart rate significantly elevates the late atrial (A) filling velocity during left ventricular filling, while early passive (E) filling velocity remains unchanged. This highlights heart rate
Area of Science:
- Cardiology
- Physiology
- Medical Imaging
Background:
- Left ventricular (LV) filling patterns are influenced by age and loading conditions.
- Existing data on heart rate's (HR) impact on transmitral flow velocities are limited and conflicting.
Purpose of the Study:
- To investigate the influence of increased heart rate on Doppler echocardiographic transmitral flow velocities.
- To clarify the relationship between heart rate and left ventricular filling patterns.
Main Methods:
- Pulsed-wave Doppler echocardiography was used in 20 healthy volunteers.
- Transmitral flow velocities (E and A waves) were measured at baseline and during atrial pacing to increase HR.
- Key parameters like peak E and A velocities and integrated E filling were analyzed.
Main Results:
- Increased heart rate did not significantly alter peak early passive (E) filling velocities.
- Peak and integrated late atrial (A) filling velocities showed a significant increase with higher heart rates.
- A strong linear relationship was observed between heart rate and peak A velocity.
Conclusions:
- Heart rate significantly impacts the late atrial component of left ventricular filling.
- Doppler echocardiography reveals that increased heart rate primarily affects the A wave, not the E wave, of transmitral flow.
- Findings contribute to a better understanding of physiological determinants of LV filling dynamics.
Abstract:
Although a number of factors, including age and ventricular loading, are known to influence the pattern of left ventricular (LV) filling as depicted by Doppler echocardiographic transmitral flow velocities, few and conflicting data are available regarding the influence of heart rate (HR). Therefore, 20 volunteers (mean age 30 years) were evaluated with pulsed-wave Doppler echocardiography, performed with the sample volume placed at the mitral anulus level in the apical 4-chamber projection. Transmitral flow measurements comprised peak and integrated early passive (E) and late atrial (A) filling velocities and the slope of velocity decline from peak E filling. Measurements were recorded during baseline (sinus rhythm, mean 70 beats/min) and during transesophageal atrial pacing (mean 88 beats/min). LV end-diastolic dimension, mean arterial pressure and PR interval (corrected for pacing-induced delay in interatrial conduction time) were unchanged during pacing versus baseline measurements. Peak and integrated E filling velocities averaged 0.59 +/- 0.09 m/s and 6 +/- 1 cm, respectively, at baseline and were not significantly greater at the higher HR. In contrast, baseline peak and integrated A velocities averaged 0.37 +/- 0.06 m/s and 2.3 +/- 0.7 cm, respectively, but were significantly greater at the higher HR (0.5 +/- 0.07 m/s and 3.2 +/- 1.1 cm, respectively [p less than 0.003 vs baseline for each]). Further analysis of a subgroup of 9 subjects for whom Doppler measurements were available at 3 HRs (sinus 70; pacing 80 and 90) yielded strong evidence for a linear relation between HR and peak A velocity (A = 0.008 HR - 0.21, with p less than 0.0001 for significance of the linear trend).(ABSTRACT TRUNCATED AT 250 WORDS)