Patients who present to the emergency department reporting palpitations generally are placed into one of three pathophysiologic categories: those with tachyarrhythmias or premature contractions, those with chest wall causes, and those without discernible cause. All patients who present with palpitations must be promptly evaluated: first, for hemodynamic stability as determined by the pulse and blood pressure; and second, for the presence or absence of clinical or electrocardiographic (ECG) evidence of ventricular dysfunction or myocardial ischemia, respectively. The heart rate and rhythm may then be assessed, because these often provide the only clue to the cause of the dysrhythmia, especially if palpitations are paroxysmal and not present when the patient is subsequently evaluated. In all patients, the presence of chest pain, lightheadedness, or dyspnea in association with palpitations must be carefully investigated. An ECG is essential for all patients, and if the palpitations are paroxysmal or associated with significant symptoms, in-hospital monitoring, a 24-hour Holter monitor, and/or exercise testing may be required to unmask potential dysrhythmias.

There are two distinct classes of dysrhythmia that commonly produce palpitations: sustained tachyarrhythmias and premature depolarizations. It is interesting and remains unexplained that only some patients with these disorders sense or are troubled by palpitations. An important but benign cause for palpitations is simply forceful ventricular contractions often associated with anxiety, excitement, or exercise. Chest wall muscle contractions may also produce the symptom of palpitations and usually require no further investigation. Finally, in a significant number of patients with palpitations, there will be no discernible cause. The remainder of this chapter presents a discussion of the differential diagnosis and treatment of the dysrhythmic causes of palpitations.

Supraventricular tachycardias (SVTs) have rates greater than 100 beats/min, the origin of which is at or above the atrioventricular (AV) node. Various methods for classifying and diagnosing these dysrhythmias exist and must be carefully followed to ensure appropriate diagnosis and therapy. A diagnostic classification can be made on the basis of three variables readily assessable from the ECG: rate, regularity, and QRS width.