Dilated cardiomyopathy is a type of heart muscle disease which is defined as dilation and impaired ventricular contraction (left ventricular dysfunction) which will lead to progressive left side heart failure and later on right sided heart failure.
It is the most common indication for heart transplant.
Biventricular Dilation:
In dilated cardiomyopathy biventricular dilation is present due to the increase of end-systolic diameter which results in problem of emptying.
This is a systolic dysfunction, not a diastolic dysfunction.
- (No problem of filling , there is a problem of emptying in DCM)
DIMINISHED CONTRACTILITY
In dilated cardiomyopathy (DCM), there is a diminished contractility because walls of the ventricular chamber set apart, their (actin, myosin) filaments are not working properly due to which they are not contracting sufficiently to perform systole and emptying which results in muscle fibers are ruptured, due to which dilation present (cardiomegaly).
CAUSES:
Possible causes of dilated cardiomyopathy:
- Idiopathic (most common)
- Alcohol
- Viral myocarditis
- Radiation
- Toxins such as (doxorubicin)
- Chagas disease
- Peripartum cardiomyopathy
- Connective tissue disease such as multiple sclerosis
CLINICAL FEATURES:
- S3 gallop rhythm.
- Features of cardiac failure, arrhythmias or thromboembolism.
- Jugular venous distension (when blood blocks in superior and inferior vena cava)
- Ventricular dilation leads to functional mitral or tricuspid valvular regurgitation.
Complications
Complications of dilated cardiomyopathy include:
- Heart failure: The heart can’t pump enough blood to meet the body’s needs. Untreated, heart failure can be life-threatening.
- Heart valve regurgitation (leaky heart valves).
- Irregular heartbeats (arrhythmias); Changes in the heart’s size and shape can interfere with the heart’s rhythm.
- Sudden cardiac arrest: Dilated cardiomyopathy can cause the heart to suddenly stop beating.
Investigations:
- Chest X-ray: shows the shape and condition of the heart (massive cardiomegaly).
- Echocardiography: reveals dilation of left and right ventricle with poor contraction.
- ECG: shows tachycardia, conduction abnormalities, ST-segment and T-wave changes.
- Cardiac catheterization: shows left ventricular dilation and dysfunction, high end diastolic pressure, low cardiac output.
Treatment:
Treatment is aimed at controlling the resulting heart failure and prevents arrhythmia by taking the following steps;
- ACEIs,ARBs and beta blockers (eg. metoprolol, spironolactone) to lower mortality.
- If ACEIs, ARBs and beta blockers are contraindicated due to any reason go for HYDRALAZINE + NITRATES.
- Use diuretics and digoxin to control symptoms.
- Biventricular pacemaker if QRS is wide (more than 120 millisecond) to improve symptoms and survival. Wider QRS means greater benefits of biventricular pacemaker.
- Automated implantable defibrillators to improve mortality in case of low ejection fraction.
- Prophylactic anticoagulation because atrial and pulmonary emboli are more common in dilated cardiomyopathy.