Afterload

Afterload is the pressure that the heart must work against to eject blood during systole (ventricular contraction).

[1] Afterload is proportional to mean systolic blood pressure and is measured in millimeters of mercury (mm Hg).

Conversely, a concentrically hypertrophied left ventricle may have a lower afterload for a given aortic pressure.

Cardiac imaging is a somewhat limited modality in defining afterload because it depends on the interpretation of volumetric data.

[5] Pulmonary hypertension (PH) is increased blood pressure within the right heart leading to the lungs.

[6] In the natural aging process, aortic stenosis often increases afterload because the left ventricle must overcome the pressure gradient caused by the calcified and stenotic aortic valve, in addition to the blood pressure required to eject blood into the aorta.

For instance, if the blood pressure is 120/80, and the aortic valve stenosis creates a trans-valvular gradient of 30 mmHg, the left ventricle has to generate a pressure of 110 mmHg to open the aortic valve and eject blood into the aorta.

[7] Due to the increased afterload, the ventricle has to work harder to accomplish its goal of ejecting blood into the aorta.

In ventricular systole under MR, regurgitant blood flows backwards/retrograde back and forth through a diseased and leaking mitral valve.