Why there is biventricular failure in dilated cardiomyopathy ?
Dilated cardiomyopathy (DCM) is a condition characterized by an enlarged and weakened heart muscle, which leads to decreased heart function. Biventricular failure, involving both the left and right ventricles, is a common manifestation of DCM. Here’s why this occurs:
- Global Myocardial Dysfunction: In DCM, the heart muscle becomes weak and is unable to contract effectively. This weakness affects both the left and right ventricles, leading to a decrease in their pumping capacity.
- Enlargement of the Heart Chambers: DCM causes the chambers of the heart, particularly the left ventricle, to enlarge. This enlargement is a compensatory mechanism to maintain cardiac output by increasing the filling capacity of the ventricles. However, the enlarged chambers also lead to thinning of the ventricular walls, making it harder for the heart to effectively pump blood.
- Impaired Contractility: The weakened heart muscle in DCM has impaired contractile ability, reducing the force with which the heart can pump blood during systole (contraction). Both the left and right ventricles struggle to effectively pump blood out to the systemic and pulmonary circulations, respectively.
- Congestive Heart Failure (CHF): As the heart’s pumping ability declines, it can’t effectively circulate blood throughout the body. Blood can back up in the lungs and systemic circulation, causing symptoms of congestive heart failure such as shortness of breath, fluid retention (edema), fatigue, and reduced exercise tolerance.
- Impact on Pulmonary Circulation: The weakened left ventricle may not effectively pump blood out to the body, causing blood to accumulate in the pulmonary circulation. This can lead to increased pressure in the pulmonary arteries, contributing to right ventricular failure.
- Compensatory Responses: Initially, the body may activate compensatory mechanisms such as the sympathetic nervous system and the renin-angiotensin-aldosterone system to try to maintain blood pressure and cardiac output. However, these compensatory responses can be detrimental in the long term and contribute to further heart damage.
In summary, dilated cardiomyopathy results in biventricular failure due to weakened and enlarged ventricles, impaired contractility, and the resulting inability of both the left and right ventricles to effectively pump blood to meet the body’s needs. This leads to congestive heart failure and its associated symptoms. Treatment typically involves medications, lifestyle modifications, and in some cases, advanced therapies like heart transplantation.