A 33-year-old man complained about chest pain on exertion. He was referred to a cardiologist, who carried out a number of studies, including right- and left-sided catheterization. Among the data obtained during these studies were the findings that at the time of his initial examination the patient's mean aortic pressure was 93 mm Hg and his mean pulmonary artery pressure was 20 mm Hg. These findings can be explained as follows:
A) The patient's systemic vascular resistance was much greater than his pulmonary vascular resistance.
B) The patient's aortic compliance was much greater than his pulmonary artery compliance.
C) The patient's left ventricular stroke volume was much greater than his right ventricular stroke volume.
D) The total cross-sectional area of the patient's pulmonary artery was much greater than the total cross-sectional area of the aorta.
E) The duration of rapid ejection phase of the patient's left ventricle exceeded the duration of the rapid ejection phase of the right ventricle.

Question

Quizplus · Accepted Answer

The difference in pressures between the aorta and the pulmonary artery is primarily due to the systemic vascular resistance being much greater than the pulmonary vascular resistance. This is because the systemic circulation has to supply blood to the entire body, requiring higher pressure, whereas the pulmonary circulation only supplies the lungs and operates at a lower pressure.

A 33-Year-Old Man Complained About Chest Pain on Exertion