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.

Delayed or lack of conduction of atrial depolarizations through the atrioventricular node to the ventricles.

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

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.

A type of cardiac arrhythmia with premature atrial contractions or beats caused by signals originating from ectopic atrial sites.

A tachycardia originating in the ventricles characterized by rapid heart rate (over 100 beats per minute) and broad QRS complexes (over 120 ms).

A diminution of the volumetric fraction of blood pumped out of the ventricle with each cardiac cycle.