Progressive Care Nursing Certification (PCCN) Practice Exam

What is the primary factor that coronary artery perfusion relies on?

1. Diastolic pressure

2. Systolic pressure

3. Afterload

4. Systemic vascular resistance (SVR)

The correct answer is: Diastolic pressure

Coronary artery perfusion primarily relies on diastolic pressure. During diastole, the heart muscle relaxes, allowing blood to flow into the coronary arteries. This is crucial since adequate coronary perfusion oxygenates the heart tissue, supporting its metabolic needs. The diastolic pressure in the aorta is particularly significant; it determines the pressure available to push blood through the coronary arteries during this resting phase. While systolic pressure reflects the force at which blood is ejected from the heart during contraction, it is during diastole that the coronary arteries receive the majority of their blood supply. Afterload and systemic vascular resistance also play roles in overall cardiovascular function but do not directly influence the perfusion of the coronary arteries as significantly as diastolic pressure does. Understanding this relationship is essential for effective management and treatment of patients with cardiovascular conditions.