Which equation expresses mean arterial pressure (MAP)?

• A. MAP equals Cardiac Output x Systemic Vascular Resistance
• B. MAP equals Heart Rate x Stroke Volume
• C. MAP equals Stroke Volume x Heart Rate
• D. MAP equals Cardiac Output / Systemic Vascular Resistance

Answer: (A)

Mean arterial pressure represents the average driving pressure in the systemic circulation, determined by how much blood the heart pumps and how much resistance the vessels offer. The standard relationship is MAP ≈ CO × SVR, where CO is cardiac output and SVR is systemic vascular resistance. Cardiac output itself is heart rate times stroke volume, so MAP ≈ (HR × SV) × SVR. The vascular resistance term is essential because higher resistance increases pressure for a given flow, while lower resistance decreases it. Therefore, the equation that expresses MAP is CO × SVR.