Pathogenesis of Right-Sided Heart Failure

Right sided heart failure is a cardiac condition when the right ventricle can’t pump strong enough to eject blood into the pulmonary vessels.  Similar to left-sided heart failure, the right heart might have problems with damage to the right ventricle wall (e.g. cardiomyopathy, previous heart attack in right heart) itself or the right heart wasn’t made quite right resulting in inadequate pumping (e.g. valvular issues, congenital heart defect on right side).  However, the more common cause of right sided heart failure is a significant increase in resistance/afterload in the lungs, a condition known as pulmonary hypertension.  The resulting alterations in the right heart, due to pulmonary hypertension, is known as cor pulmonale.

What is pulmonary hypertension?

Normally, pulmonary vessels have very low blood pressure – due to the fact that the right heart doesn’t have to push the blood very far to get to the pulmonary vessels and pulmonary vessels are larger and more distensible.

1. Pulmonary hypertension can be caused fluid overload in the pulmonary vasculature.  This fluid overload in vasculature can be a result of multiple conditions originating outside of the lungs – including the back up of blood seen in left sided heart failure.
2. Pulmonary hypertension can be caused by very strong vasoconstriction across the entire lungs – a phenomenon seen in alveoli that are globally poorly ventilated.  This occurs in patients with severe pulmonary diseases (see the Emphysema chapter)

Pathology of Right-Sided Heart Failure (DHPLC #B0606 from the Boyd Collection)

Signs and Symptoms of Right-Sided Heart Failure

^{Clinical Manifestations of Right-sided Heart Failure by Jennifer Kong, licensed under CC BY NC}

Section Review

• Right sided heart failure is caused by insufficient blood leaving the right ventricle during systole, thus causing a back up of blood into the right atrium and vena cavae.
• If the cause of the insufficient pumping is due to pulmonary hypertension, the right ventricle remodels to try to pump better, causing the cardiomyocytes to enlarge with more contractile proteins resulting in right ventricular thickening (Cor Pulmonale).
• As insufficient blood is leaving the right ventricle, blood backs up into the right atrium and then the superior and inferior vena cavae.  This excess blood will cause an overfilling of the veins which feed into the vena cavae.
• Overloaded superior vena cava will cause a back up of blood in the neck veins which is observable to health care providers.
• Overloaded inferior vena cava will lead to a back up of blood in the abdominal veins and beyond, particularly the portal vein resulting in an enlargement of the liver, congested with blood.
• Because the right ventricle can’t pump sufficient blood through the lungs, there is insufficient blood entering the left heart. Thus, signs of poor blood flow to the rest of the body (i.e. fatigue, weakness).
• Right sided heart failure can be a consequence of the pulmonary hypertension caused by left-sided heart failure, but not in all cases.

Review Questions