Question

A) What is the main effect on systemic hemodynamics from left heart failure?

B)Describe the mechanisms behind two of the systemic compensatory mechanisms triggered by left heart failure (How does the body try to compensate?).

Answer 1

A. Left heart failure generally refers to the failure of the left ventricles to supply oxygenated blood to the body parts. It either systolic failure where the heart can't pump with enough force to push enough blood into circulation or diastolic failure where the heart can't properly fill with blood during the resting period between each beat.

When the systolic failure occurs left ventricle is unable to supply the normal blood to the body parts. This deprives the body of a normal supply of blood.

When the diastolic failure occurs due to the stiffness of the left ventricle it is unable to fill the lower left chamber of the heart properly, which reduces the amount of blood pumped out to the body. Over time, this causes blood to build up inside the left atrium, and then in the lungs, leading to fluid congestion and symptoms of heart failure.

B. Compensation mechanism for diastolic failure- As the left ventricle pumps harder to compensate, it grows weaker and thinner. As a result, blood flows backwards into organs, causing fluid buildup in the lungs and/or swelling in other parts of the body.

The sympathetic nervous system is activated in heart failure, via low and high-pressure baroreceptors, as an early compensatory mechanism which provides inotropic support and maintains cardiac output. Chronic sympathetic activation, however, has deleterious effects, causing further deterioration in cardiac function.