The nurse is caring for a patient with severe coronary artery disease (CAD) who is experiencing chest pain because the oxygen demand exceeds supply. What forces could potentially be lowered to reduce oxygen consumption? (Select all that apply.)
A) Pulse pressure
B) Afterload
C) Stretch on the ventricles
D) Heart rate
E) Preload
B, C, D, E
Feedback:
The primary forces that determine the heart's use of oxygen or oxygen consumption include: Heart rate (the more the heart has to pump, the more oxygen it requires), preload (the more blood that is returned to the heart, the harder it will have to work to pump the blood around), afterload (the higher the resistance in the system, the harder the heart will have to contract to force open the valves and pump the blood along), and stretch on the ventricles (if the ventricular muscle is stretched before it is stimulated to contract, more actomyosin bridges will be formed, which will take more energy). Pulse pressure does not impact oxygen consumption.
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