Question

An increase in what two things is associated with the highest increase in myocardial O2 consumption?

a) Heart rate and contractility
b) Blood pressure and stroke volume
c) Coronary artery diameter and blood flow
d) Cardiac output and blood viscosity

Answer 1

An increase in heart rate and contractility is associated with the highest increase in myocardial O2 consumption, raising the heart's oxygen demand.

Step-by-step explanation:

The increase in myocardial O2 consumption is most closely associated with an increase in heart rate and contractility. When the heart rate (the frequency of heart contractions) and contractility (the force with which the heart contracts) increase, there is a subsequent rise in myocardial O2 consumption because the heart needs more oxygen to perform this higher level of activity. This not only elevates cardiac output but also increases the demand for oxygen by the myocardial tissue.