Cardiac output is determined by which two factors?

Cardiac output is determined by which two factors?

• A. Stroke volume and heart rate
• B. Blood pressure and heart rate
• C. Preload and afterload
• D. Venous return and afterload

Answer: (A)

Cardiac output depends on two direct components: the amount of blood the heart ejects with each beat (stroke volume) and how frequent those beats are (heart rate). The relationship is CO = SV × HR, so increasing either stroke volume or heart rate raises cardiac output. Stroke volume itself is shaped by preload (the filling of the heart), afterload (the pressure the heart must work against), and contractility, while heart rate is controlled by autonomic input and other factors. Blood pressure, preload, and afterload are related but do not directly determine cardiac output the way stroke volume and heart rate do.

Cardiac output depends on two direct components: the amount of blood the heart ejects with each beat (stroke volume) and how frequent those beats are (heart rate). The relationship is CO = SV × HR, so increasing either stroke volume or heart rate raises cardiac output. Stroke volume itself is shaped by preload (the filling of the heart), afterload (the pressure the heart must work against), and contractility, while heart rate is controlled by autonomic input and other factors. Blood pressure, preload, and afterload are related but do not directly determine cardiac output the way stroke volume and heart rate do.