An atrial arrhythmia characterized by disorganized atrial activity without discrete P waves on the surface EKG, but instead by an undulating baseline or more sharply circumscribed atrial deflections of varying amplitude an frequency ranging from 350 to 600 per minute.

Dilated cardiomyopathy is a form of heart disease in which the heart (cardiac) muscle becomes thin and enlarged (dilated). The dilation, which typically starts in the lower left chamber of the heart (left ventricle), makes it harder for the heart to pump blood to the rest of the body. \n\nDilated cardiomyopathy is called nonsyndromic dilated cardiomyopathy when it cannot be explained by other causes, such as a heart attack or damage to the valves of the heart, and is not associated with signs and symptoms that affect other parts of the body.  \n\nThe signs and symptoms of nonsyndromic dilated cardiomyopathy vary among affected individuals, even among members of the same family. The signs and symptoms typically begin in mid-adulthood, but they can occur at any time from infancy to late adulthood. Affected individuals may have a sensation of fluttering or pounding in the chest (palpitations); shortness of breath, especially when lying down or during physical activity; fatigue; and swelling of the legs and feet. Affected individuals may also have episodes of dizziness or fainting (syncope). \n\nOver time, people with nonsyndromic dilated cardiomyopathy may develop life-threatening complications, which can include abnormal heart rhythms (arrhythmias) and heart failure. Although uncommon, sudden death can occur in people with nonsyndromic dilated cardiomyopathy, even if they have no other symptoms of the condition.\n\n

Hypertrophic cardiomyopathy (HCM) is defined by the presence of increased ventricular wall thickness or mass in the absence of loading conditions (hypertension, valve disease) sufficient to cause the observed abnormality.

The presence of an abnormality of cardiac function that is responsible for the failure of the heart to pump blood at a rate that is commensurate with the needs of the tissues or a state in which abnormally elevated filling pressures are required for the heart to do so. Heart failure is frequently related to a defect in myocardial contraction.

An abnormality of the mitral valve characterized by insufficiency or incompetence of the mitral valve resulting in retrograde leaking of blood through the mitral valve upon ventricular contraction.

Enlargement or increased size of the heart left ventricle.

The dividing wall between left and right sides of the heart, thickens and bulges into the left ventricle.

Abnormally high volume of blood in the left ventricle at the end of diastole (just before systole).