CVS Practice Test

Increased tachycardia, which refers to a faster heart rate, leads to an increased demand for ATP and oxygen consumption in cardiac myocytes. This occurs because, as the heart beats more rapidly, the myocardial cells require more energy to contract efficiently and maintain proper blood flow.

This increased energy demand translates into a higher consumption of oxygen since the oxidative phosphorylation pathway, which takes place in the mitochondria, is the primary method by which heart cells generate ATP. With the heart beating faster, the cardiac muscle cells are not only contracting more frequently, but they also have less time to rest between beats. This reduction in diastolic filling time means that while the heart is working harder, it must also ensure adequate blood supply to meet the metabolic needs during contractions.

Therefore, the combination of increased heart rate and the necessity for enhanced energy production clearly indicates that both ATP and oxygen consumption will greatly increase in response to tachycardia, making the first choice the appropriate and correct response.