Question

A 50-year-old accountant who was admitted to the hospital. His past medical history indicates that he is on no medication and seemed to be a reasonably fit man for his age with no existing diagnosed medical conditions. He weighs 192 lbs, smokes 20 cigarettes per day and drinks “a beer or two most days” and eats a typical American diet. His blood pressure on admission was 165/80 mmHg with a heart rate of 90 beats per minute. At first, the ER staff felt this was due to the stress of hospitalization with the addition of the COVID -19 scare. However, this elevated blood pressure and heart rate were maintained over 48 hours. Thus, he was diagnosed as having hypertension.

a) Where does afterload fit into all of this?
b) What would be the normal reflex response of the cardiovascular system in response to an elevated cardiac output?

Answer 1

(a) Systemic hypertension increases the left ventricular afterload because the left ventricle has to work hard to eject blood into the aorta. This is so as the aortic valve will not open until the pressure generated in the left ventricle is higher than the elevated blood pressure in the aorta.

(b) It occurs when the heart rate elevates in response to a rise in atrial pressure. It is a compensatory mechanism because increased right atrial pressures often result from raised left heart pressures from decreased cardiac output.