Cor pulmonale

With cor pulmonale, cor is Latin for heart and pulmonale is Latin for lungs. Cor pulmonale, then, is a relationship between the two, it’s when a disorder of the lungs causes dysfunction of the heart.

Normally, de-oxygenated venous blood from the body goes into the right atrium of the heart. From there, it goes into the right ventricle and gets pumped into the lungs where it is reoxygenated as it goes through the pulmonary circulation.

The pulmonary circulation is a low-resistance system with pressures ranging between 10 mmHg and 14 mmHg. After going through the lungs, oxygenated blood goes into the left atrium, and then into the left ventricle, and finally gets pumped back out to the body.

When the heart can’t pump enough blood to meet the body’s demands, it’s initially called heart dysfunction and can worsen to the point where it’s called heart failure.

This can happen in two ways, either it’s systolic heart failure, where the ventricles can’t pump blood hard enough during systole, or diastolic heart failure, where not enough blood fills the ventricles during diastole, called diastolic heart failure.

Heart failure can affect the right ventricle, the left ventricle, or both ventricles, so someone might have, right-sided heart failure, left-sided heart failure, or both which is called biventricular heart failure.

Cor pulmonale is when a lung disorder causes right-sided heart dysfunction that can develop into right-sided heart failure.

Lung disorders make it harder to oxygenate the blood, which can lead to hypoxia, or low oxygen levels. In response, this triggers a process called hypoxic pulmonary vasoconstriction.

Let’s say you have a couple pulmonary arterioles here, meaning they’re in the lungs, and the alveoli of the lungs here, and oxygen exchange between the two.

If one of these alveoli is poorly ventilated, the corresponding arteriole vasoconstricts to divert blood away from it. This works pretty well, but when lots of alveoli are poorly ventilated like with a lung disorder, they all start to vasoconstrict and the mechanism backfires.

When lots of arterioles vasoconstrict together, there’s an increase in resistance and it leads to pulmonary hypertension - with the pulmonary blood pressure rising above 25 mm Hg.

The high pulmonary pressure makes it hard for the right ventricle to pump blood into the pulmonary circulation. As compared to the left side, the right side of the heart is thinner walled and used to ejecting against a low pulmonary vascular resistance.

In acute lung disorders, like a pulmonary embolism, where a blood clot blocks blood flow in a pulmonary artery, the result is a rapid increase in right ventricular pressure that makes the right ventricle stretch out like a water balloon.

In chronic lung disorders, prolonged high pressure causes the right ventricle to hypertrophy, or grow, so it can contract with more force.

The hypertrophy is concentric, which means that the new sarcomeres are generated in parallel with existing ones. So as the heart muscle wall enlarges, it crowds into the ventricular chamber space, resulting in less room for blood to fill the heart, and that leads to diastolic heart failure.

The increase in right ventricular muscle mass also means that there is a greater demand for oxygen, and, to make matters worse, the coronaries get squeezed down by the this extra muscle so that even less blood’s delivered to the right ventricle.

More demand and reduced supply leads to right ventricular ischemia and that leads to weaker contractions and systolic failure.

Cor pulmonale results from pulmonary hypertension, which typically comes from one of three categories of diseases - something that damages the lung tissue, like chronic obstructive pulmonary disease, something that damages the pulmonary vessels themselves, like chronic thromboembolisms or recurrent blood clots, something that affects the spine or ribcage, like kyphoscoliosis, where the spine is curved and the lungs can’t fully expand.

An important distinction is left heart dysfunction or failure, which can result in pulmonary hypertension, but wouldn’t be considered cor pulmonale because the initial problem is with the heart itself, not the lungs.

Primary right sided heart failure (might happen after a right ventricular myocardial infarction or as a consequence of pulmonary valve stenosis) would also not be considered cor pulmonale as the underlying defect is related to the heart not the lungs.

Because cor pulmonale stems from pulmonary hypertension, the symptoms are all related to the backup of blood in the venous system.

Pulmonary hypertension can lead to severe shortness of breath, fatigue, and fainting and right-sided heart failure can cause blood to get backed up coming from the body, causing jugular venous distension, hepatomegaly, and edema.

The diagnosis of cor pulmonale is usually made with an echocardiogram that shows evidence of increased pressure in the pulmonary arteries and right ventricle.

Follow up tests can be done to identify the underlying cause, for example spirometry can be done to look for chronic lung disease.

The gold standard diagnostic test to directly measure pulmonary pressures and assess for response to vasodilating medications is a right heart catheterization.

Treatment for cor pulmonale targets this underlying lung condition. Supplemental oxygen can help with hypoxia-induced vasoconstriction.

All right, as a quick recap…Cor pulmonale is right heart hypertrophy, dysfunction or failure caused by pulmonary hypertension from a lung condition.

This results in systemic fluid congestion leading to jugular venous distension, hepatomegaly, and edema. After diagnosis with echocardiography, right heart catheterization and potentially spirometry, treatment includes addressing the underlying lung condition and administering supplemental oxygen.