Cardiac Arrhythmias

Cardiac arrhythmias are disturbances in the rhythm of the heart, manifested by irregularity or by abnormally fast rates (tachycardias) or abnormally slow rates (bradycardias). Patients who perceive these abnormalities most frequently observe palpitations,which somedescribe as the sensation of ‘my heart turning over in my chest’, or awareness that their hearts are beating rapidly or slowly. Other symptoms include weakness, shortness of breath, lightheadedness, dizziness, fainting (syncope) and, occasionally, chest pain. The symptoms tend to be more severe when the rate is faster, the ventricular function is worse, or the arrhythmia is associated with abnormalities of autonomic tone. However, many patients with arrhythmias report no symptoms, and the condition may first be discovered during a routine examination. A tachyarrhythmia that is rapid enoughand lasts long enough canproduce cardiomyopathy and congestive heart failure. In these cases, treatment of the arrhythmia can often return normal function to the ventricles. Although certain physical signs present during arrhythmias can help the physician make a correct diagnosis, electrocardiography is the standard method used for recognizing cardiac arrhythmias. A prolonged electrocardiographic recording, often called a ‘Holtermonitor’, or an event recorder that the patient activates when sensing an abnormality, may assist in confirming the diagnosis when the arrhythmia occurs sporadically, as is often the case.