Physician Assistant College Admission Test (PA-CAT) Practice Exam 2025 – The All-in-One Guide to Secure Your Admission!

In tachycardia, the heart beats at an accelerated rate, which results in a shorter diastolic period. During diastole, the heart muscle receives its blood supply primarily through the coronary arteries, which fill during this resting phase. When the diastolic phase is shortened due to rapid heartbeats, there is less time for the coronary vessels to fill with blood.

As a consequence, the overall coronary blood flow decreases. This reduction can lead to insufficient oxygen delivery to the myocardial tissue, potentially causing ischemia, particularly in individuals with pre-existing coronary artery disease. Furthermore, the increased heart rate can raise myocardial oxygen demand, while the decreased diastolic duration may not adequately meet this demand, leading to compromised myocardial perfusion.

Recognizing this relationship is critical for understanding how cardiac rhythm impacts coronary circulation and highlights the importance of managing conditions like tachycardia to maintain adequate coronary blood flow and myocardial health.