Myocardial blood flow is predominantly observed during which phase of the cardiac cycle?

Myocardial blood flow is predominantly observed during diastole. During this phase of the cardiac cycle, the heart muscle relaxes, allowing the coronary arteries to fill with blood. This is crucial as the coronary circulation primarily occurs when the heart is not contracting. While the heart is in systole, the contraction of the myocardium compresses the coronary vessels, reducing blood flow. Hence, the majority of perfusion to the myocardium takes place during diastole when the heart's chambers are filling with blood and the myocardial workload is relatively low. Understanding this dynamic is essential in assessing coronary perfusion and ensuring adequate oxygen supply to the heart muscle, which is vital for normal cardiac function.