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[Intracardiac hemodynamics in heart rhythm acceleration and the development of an angina attack]
Insights
Atrial stimulation during echocardiography revealed that increased heart rate reduces left-ventricular end-diastolic diameter but doesn't alter ejection fraction. Myocardial ischemia, however, causes asynergy and reduced cardiac function before ECG changes.
Area of Science:
- Cardiology
- Medical Imaging
- Physiology
Background:
- Echocardiography is crucial for assessing cardiac function.
- Atrial stimulation tests can reveal hemodynamic changes.
- Ischemic heart disease affects myocardial contractility and dimensions.
Purpose of the Study:
- To evaluate the impact of accelerated cardiac rhythm on left ventricular dimensions and function.
- To identify echocardiographic indicators of myocardial ischemia during atrial stimulation.
Main Methods:
- Echocardiography was performed on 15 patients during atrial stimulation.
- Patients were divided into an ischemic heart disease group (8) and a control group (7).
- Key echocardiographic parameters including left-ventricular end-diastolic diameter, ejection fraction, and velocity of circumferential fiber shortening (Vcf) were measured.
Main Results:
- Accelerated heart rate proportionally decreased left-ventricular end-diastolic diameter and increased Vcf and diastolic myocardial thickness.
- Ejection fraction, minute volume, and left-ventricular activity index remained unchanged with increased heart rate.
- Myocardial ischemia led to asynergy, decreased ejection fraction, Vcf, left-ventricular activity index, and minute volume, with increased left-ventricular end-diastolic diameter.
Conclusions:
- Increased heart rate affects ventricular dimensions and myocardial contractility without altering ejection fraction in healthy individuals.
- Echocardiographic changes like asynergy and increased end-diastolic diameter precede ECG changes and angina in myocardial ischemia.
- Echocardiography during atrial stimulation is valuable for detecting early signs of myocardial ischemia.
Abstract:
Fifteen patients were examined by echocardiography during the atrial stimulation test. The patients were divided into 2 groups: the main group of 8 patients with ischemic heart disease and a control group of 7 persons wit a negative bicycle ergometry test and no changes in the coronary arteries. It is shown that acceleration of the cardiac rhythm leads to a proportional decrease in the left-ventricular end-diastolic diameter and increase in Vcf and diastolic thickness of the myocardium; the ejection fractions, minute volume and index of left-ventricular activity do not change. It was revealed that the development of myocardial ischemia leads to myocardial asynergy, decrease in the ejection fraction. Vcf, index of left-ventricular activity and minute volume and to an increase in the end-diastolic diameter of the left ventricle, which precede the ECG changes and the development of an angina attack.