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[Effect of rapid atrial pacing on left ventricular ejection fraction in patients without organic heart disease]
Insights
Rapid atrial pacing significantly decreased left ventricular ejection fraction (LVEF) in healthy individuals, challenging previous assumptions about normal responses. This study clarifies pacing effects on cardiac function in a homogeneous group without coronary artery disease.
Area of Science:
- Cardiology
- Physiology
Context:
- Previous studies on pacing-induced left ventricular ejection fraction (LVEF) changes in healthy individuals are limited by heterogeneous populations and varied LVEF measurement methods.
- The response of LVEF to rapid atrial pacing in individuals without coronary artery disease is not well-defined.
Purpose:
- To assess pacing-induced changes in left ventricular ejection fraction (LVEF) in a homogeneous group of patients with normal coronary arteriograms and baseline left ventricular function.
Summary:
- Ten patients without coronary artery disease underwent stepwise rapid atrial pacing up to 150 bpm.
- Biplane ventriculography revealed a significant decrease in LVEF from 75% to 66% (p < 0.005) despite decreased end-diastolic volume index and unchanged systolic volume index.
- No evidence of myocardial ischemia or limited coronary reserve was observed.
Impact:
- This study demonstrates that a decrease in LVEF during rapid atrial pacing is a normal physiological response in individuals without coronary artery disease.
- Findings challenge the notion that a decreased LVEF during pacing indicates myocardial ischemia in all patient groups.
- Provides a clearer understanding of cardiac hemodynamics during rapid atrial pacing in healthy hearts.
Abstract:
Pacing-induced decrease of left ventricular ejection fraction (LVEF) in patients with coronary artery disease has been proposed as a sign of myocardial ischemia, whereas a slight increase or no change is speculated to be the normal response to rapid atrial pacing. The studies of the pacing-induced effects in normals, however, are of limited value, because of either inhomogeneous patient population or different, mainly non-invasive, methods for determination of LVEF. It was therefore the aim of the present study to assess the pacing-induced changes of left ventricular ejection fraction in a homogeneous group of patients. In 10 patients (mean age: 48 +/- 2 years) with normal coronary arteriograms and normal LV-function at rest, rapid atrial pacing was performed stepwise to a maximal pacing rate of 150 beats per minute. In all patients left ventricular end-diastolic pressure LVEDP and time constant of relaxation period tau decreased, while the parameter of contractility Max Dp/dt increased due to increase in heart rate. Furthermore, there was no limited coronary reserve or myocardial lactate production during atrial stimulation as a sign of pacing-induced ischemia. In all patients biplane ventriculography was performed at rest and during maximal stimulation. While end-diastolic volume index EDVI decreased in every patient (71 +/- 5----42 +/- 4 ml/m2, p less than 0.005) and systolic volume index did not change (17 +/- 2----14 +/- 2 ml/m2, N.S.), there was a significant decrease of ejection fraction from 75 +/- 2 to 66 +/- 3% (p less than 0.005). Basal heart rate, age, sex or basal ejection fraction did not influence the response of ejection fraction to rapid atrial pacing. Even after drug-induce afterload reduction there was a significant pacing induced decrease of ejection fraction.(ABSTRACT TRUNCATED AT 250 WORDS)