What is the normal systemic vascular resistance (SVR) range?

What is the normal systemic vascular resistance (SVR) range?

• A. 600-900 dynes·s/cm5
• B. 1000-1400 dynes·s/cm5
• C. 800-1200 dynes·s/cm5
• D. 1200-1600 dynes·s/cm5

Answer: (C)

Systemic vascular resistance represents the afterload the left ventricle must overcome from the systemic circulation. It is calculated from mean arterial pressure, right atrial pressure, and cardiac output using SVR = (MAP − RAP) / CO × 80, with units in dynes·s/cm5. With typical resting values—MAP around 90–100 mmHg, RAP about 0–5 mmHg, and CO about 4–8 L/min—the calculation commonly falls in the 800–1200 dynes·s/cm5 range. This is why 800–1200 is considered the normal SVR range. Values well below this suggest systemic vasodilation or low vascular tone, while values above indicate vasoconstriction or increased afterload.

Systemic vascular resistance represents the afterload the left ventricle must overcome from the systemic circulation. It is calculated from mean arterial pressure, right atrial pressure, and cardiac output using SVR = (MAP − RAP) / CO × 80, with units in dynes·s/cm5. With typical resting values—MAP around 90–100 mmHg, RAP about 0–5 mmHg, and CO about 4–8 L/min—the calculation commonly falls in the 800–1200 dynes·s/cm5 range. This is why 800–1200 is considered the normal SVR range. Values well below this suggest systemic vasodilation or low vascular tone, while values above indicate vasoconstriction or increased afterload.