Dilated Cardiomyopathy

A dilated cardiomyopathy (CMD) is a form of Cardiomyopathie (literally, disease of the cardiac muscle ) in which the cardiac cavities (mainly the ventricles) are dilated (with various degrees), decreasing to a significant degree the capacity of the cardiac muscle to provide its function of " pompe" , thus consuisant with the Cardiac failure and coupled to a risk of Sudden death, whatever the stage of the disease.

There exist four great types of Cardiomyopathie S: the hypertrophic Cardiomyopathie, the restrictive Cardiomyopathie, the ventricular cardimyopathy right arythmogene and dilated cardiomyopathy.

The latter is the most current form of cardiomyopathy.

Epidemiology

Dilated cardiomyopathy idiopathic key more frequently men than the women, between 20 and 60 years, with a peak of frequency between 20 and 40. But it can also be met in the children.

The cause of dilated the cardiomyopathies known as " secondaires" most frequently met in France chronic alcoholism is the .

Physiopathology

Physiopathological mechanisms

The progression of the Cardiac failure is associated with modifications of the cardiac cavities. This phenomenon, physiological by an adaptation mechanism of the heart to news " conditions Hémodynamique s" leads to a replanning of the cardiac cavities of which the left ventricle. This one increases its volume telediastolic then its volume telesystolic. The difference between volume telediastolic and telesystolic corresponds to the systolic Volume of ejection (VES), which conditions the cardiac Débit. One appreciates it by the Fraction of ejection (Fe).

This increase in blood volumes will compensate, initially, according to a law known as " law of Starling" (see article " Edema ") reduction in the myocardic contractility thus allowing a conservation of the cardiac Flow. This replanning will be accompanied by a modification as of its walls, usually a thinning, of a formal amendment of the ventricle which becomes more spherical and less lengthened. This process will lead to a progressive decline of the fraction of ejection, Rickettiose, Mononucléose,…), auto-immune (érythémateux Lupus disseminated, Scleroderma, knotty Periarteritis,…), Sarcoidosis, related to a extrinsinque cardiomyopathy (ischemic, hypertensive,…).

Approximately 20 to 40% of the forms are known as family, related to change S of Gène S coding various Protéine S present in the muscular cells myocardic.
La disease is genetically heterogeneous, but generally, it is about a dominant autosomic Transmission (such as for example in the Syndrome of Alström). Recessive autosomic forms , with transmission related to X (dominant or recessive) or with Transmission mitochondriale were also described.

Genetic Cardiomyopathies

Diagnosis

Functional signs

For certain subjects, the dilated cardiomyopathy will not involve major functional signs (even not of signs of the whole) and thus not or little to resound on quality of life, nor over the lifespan. The disease can thus be discovered in a fortuitous way, at the time of the realization of certain examinations (electrocardiogram, pulmonary Radiographie ).

However, it will be able to exist a certain number of Symptôme S. the major symptom is the Dyspnée of effort (breathlessness at the time of the realization of more or less great efforts). Can join it a Asthénie, Palpitation S, thoracic waves pains insensitive with the trinitrine, Malais are and Syncope S, of the demonstrations thrombo - embolic and sometimes a risk of Sudden death.
Des signs of Cardiac failure right and left will be able to develop gradually. It should be noted that a dilation of the left ventricle can be present since months (sometimes even of the years) before a subject becomes symptomatic.

Clinical examination

The clinical exman will be able to find a Tachycardie, a noise of gallop, a Heart murmur of mitral Insuffisance or tricuspide functional (which is not with a organic lesion of the cardiac valves), signs of Cardiac failure.
A a advanced stage of the disease, the blood Pressure is low.

Complementary examinations

A pulmonary Radiographie will be able to highlight, in the already advanced forms, an increase in size of the cardiac silhouette (Cardiomégalie) important (cardio-thoracic index higher than 0.60 in 30% of the cases). Cardiac dilation appears total (although interesting mainly the left ventricle). It can also discover anomalies related to the low cardiac flow (pulmonary edema), épanchement pleural, .....
En radioscopy, the Cœur appears not very mobile.

The electrocardiogram is used to detect the existence of a cardiac pathology, without determining the cause of it, and to detect complications like Troubles cardiac rhythm (auricular Fibrillation, ventricular arrhythmias,…) or of the conduction. It can however be normal.

The cardiac echography is the examination essential with the diagnosis. It shows a total cardiac dilation with a wall normal or thinned on the level of the inter-ventricular septum, diameters telediastolic