Elevation of which parameter would most directly increase afterload?

Elevation of which parameter would most directly increase afterload?

• A. Cardiac output
• B. Systemic vascular resistance (SVR)
• C. Pulmonary capillary wedge pressure
• D. Heart rate

Answer: (B)

Afterload is the pressure the ventricle must generate to open the aortic valve and push blood into the arterial system. Elevating systemic vascular resistance raises arterial pressure, so the ventricle must work against a higher pressure with each beat. That direct rise in the pressure the heart must overcome is what increases afterload most. Cardiac output is the amount pumped per minute and can be affected by afterload, but it doesn’t set the resistance the ventricle faces. Pulmonary capillary wedge pressure reflects left atrial pressure and preload, not the resistance of the systemic circulation. Heart rate changes cardiac output and workload but does not directly increase the resistance the ventricle must overcome.

Afterload is the pressure the ventricle must generate to open the aortic valve and push blood into the arterial system. Elevating systemic vascular resistance raises arterial pressure, so the ventricle must work against a higher pressure with each beat. That direct rise in the pressure the heart must overcome is what increases afterload most.

Cardiac output is the amount pumped per minute and can be affected by afterload, but it doesn’t set the resistance the ventricle faces. Pulmonary capillary wedge pressure reflects left atrial pressure and preload, not the resistance of the systemic circulation. Heart rate changes cardiac output and workload but does not directly increase the resistance the ventricle must overcome.