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Effects of heart rate changes on left ventricular volume and ejection fraction: a 2-dimensional echocardiographic
Insights
Two-dimensional echocardiography effectively analyzes changes in left ventricular (LV) volumes and ejection fraction (EF) with increasing heart rate. This method proved reliable across normal subjects and patients with heart conditions.
Area of Science:
- Cardiology
- Medical Imaging
- Echocardiography
Background:
- Assessing left ventricular (LV) function is crucial in cardiology.
- Understanding the impact of heart rate on LV volumes and ejection fraction (EF) is essential for diagnosis and management.
- Two-dimensional (2-D) echocardiography is a widely used imaging modality.
Purpose of the Study:
- To analyze the influence of heart rate on LV volumes and EF using 2-D echocardiography.
- To validate 2-D echocardiography's accuracy in reflecting changes in LV function during atrial pacing.
- To compare the effects of heart rate on LV function in normal subjects versus patients with coronary heart disease and dilated cardiomyopathy.
Main Methods:
- 13 normal subjects, 23 coronary heart disease patients, and 8 dilated cardiomyopathy patients were studied.
- Heart rate was increased from 80 to 140 beats/min using atrial pacing while maintaining constant LV scanning with a 2.25 MHz electronic sector scanner.
- End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and EF were calculated using the disc method from stored 2-D echocardiograms.
Main Results:
- Constant LV scanning was confirmed by comparing 2-D echocardiograms with cineventriculograms.
- Percent changes in LV volumes and EF determined by 2-D echocardiography correlated well with cineventriculography.
- In normal subjects, increased heart rate reduced EDV, ESV, SV, and EF. Patients showed different absolute and percent changes in these parameters.
Conclusions:
- 2-D echocardiography is a reliable method for analyzing changes in LV function with varying heart rates.
- The study highlights distinct responses of LV volumes and EF to heart rate changes in normal individuals versus cardiac patients.
- Findings underscore the utility of 2-D echocardiography in evaluating cardiac performance under stress conditions.
Abstract:
The influence of heart rate on left ventricular (LV) volumes and ejection fraction (EF) using 2-dimensional (2-D) echocardiography during atrial pacing was analyzed. The study was performed in 13 normal control subjects, 23 patients with coronary heart disease and 8 patients with dilated cardiomyopathy. An electronic sector scanner (2.25 MHz, 84 degrees) was used. Under constant scanning of the left ventricle, heart rate was increased, in steps of 20 beats/min, from 80 to 140 beats/min. The 2-D echocardiograms were stored on videotape and analyzed off-line. The end-diastolic and end-systolic volumes (EDV and ESV) were determined using a disc method. Stroke volume (SV) and EF were calculated. Constant LV scanning was possible during atrial stimulation, as shown by the analysis of simultaneously recorded 2-D echocardiograms and cineventriculograms at different heart rates, revealing a constant position of the echocardiographic transducer. Simultaneous recordings of cineventriculography and 2-D echocardiography at 80 and 120 beats/min showed that despite differences in absolute values, percent changes of LV volumes and EF determined with both methods were similar. Thus, changes of LV function can be analyzed by 2-D echocardiography. In normal control subjects, an increase in heart rate of 10 beats/min reduced EDV by 4 ml, ESV by 2 ml, SV by 2 ml and EF by 1%, corresponding to percent reductions of 4, 2, 5 and -2%, respectively. In contrast, the absolute decreases in the patients were 6 ml, 1 ml, 5 ml and 2% and the percent changes 2%, 1%, 8% and 5%.(ABSTRACT TRUNCATED AT 250 WORDS)