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Noninvasive assessment of pacemaker hemodynamics by Doppler echocardiography: importance of left atrial size
Insights
Maintaining atrioventricular (AV) synchrony is crucial for cardiac output. Doppler echocardiography reveals that patients with normal left atrial size are more sensitive to loss of AV synchrony during ventricular pacing.
Area of Science:
- Cardiology
- Medical Devices
Background:
- Ventricular pacing can decrease cardiac output compared to physiologic pacing.
- Identifying patients who benefit from atrioventricular (AV) synchrony is important for optimizing pacemaker function.
Purpose of the Study:
- To assess the relative decrease in cardiac output with ventricular pacing versus physiologic pacing modes.
- To determine if left ventricular size, function, or left atrial size best identifies patients benefiting from AV synchrony.
Main Methods:
- Noninvasive Doppler echocardiography was used in 26 patients.
- Measurements included relative cardiac output (flow velocity integral), left ventricular size and function, and left atrial size.
Main Results:
- Loss of AV synchrony decreased relative cardiac output by 0-43% (mean 21%).
- Left ventricular size and function did not correlate with pacing mode effects.
- Normal left atrial size correlated with greater sensitivity to loss of AV synchrony (32% decrease in flow velocity integral).
- Left atrial enlargement showed less sensitivity (11% decrease).
Conclusions:
- Doppler echocardiography can assess optimal pacing modes.
- Left atrial size may identify patients who significantly benefit from maintaining physiologic pacing and AV synchrony.
Abstract:
The relative decrease in cardiac output with ventricular pacing versus "physiologic" modes was measured noninvasively using Doppler echocardiography in 26 patients. Standard echocardiographic measurements of left ventricular size (diastolic diameter), left ventricular function (shortening fraction) and left atrial size were examined to determine which of these variables might best identify patients more likely to benefit from maintenance of atrioventricular (AV) synchrony. Decreases in relative cardiac output, expressed as reduction in the Doppler-derived flow velocity integral, with loss of AV synchrony ranged from 0 to 43% (mean decrease 21%). There was no correlation between left ventricular size or function and effect of pacing mode on relative cardiac output. There was, however, correlation between left atrial size and sensitivity to pacing mode. Patients with normal left atrial size were significantly more sensitive to loss of AV synchrony. In this subgroup, the decrease in flow velocity integral with ventricular pacing was 32 +/- 11% compared with only 11 +/- 13% in patients with left atrial enlargement. Thus, Doppler echocardiography is useful in assessing optimal pacing mode in the individual patient. Echocardiographically measured left atrial size may identify patients in whom physiologic pacing may be major benefit.