Which of the following changes will cause an increase in myocardial $\mathrm{O}_{2}$ consumption?

Question

Quizplus · Accepted Answer

[IV I]. Myocardial $\mathrm{O}_{2}$ consumption is determined by the amount of tension developed by the heart. It increases when there are increases in aortic pressure (increased afterload), when there is increased heart rate or stroke volume (which increases cardiac output), or when the size (radius) of the heart is increased ( $\mathrm{T}=\mathrm{P} \times \mathrm{r}$ ). Influx of $\mathrm{Na}^{+}$ions during an action potential is a purely passive process, driven by the electrochemical driving forces on $\mathrm{Na}^{+}$ions. Of course, maintenance of the inwardly directed $\mathrm{Na}^{+}$gradient over the long term requires the $\mathrm{Na}^{+}-\mathrm{K}^{+}$pump, which is energized by adenosine triphosphate (ATP).

Which of the Following Changes Will Cause an Increase in Myocardial