The mechanisms responsible for the sensation of palpitations are unknown. Ordinarily, sinus rhythm at a normal rate is not perceived, and palpitations thus usually reflect changes in cardiac rate or rhythm. In all cases, it is the abnormal movement of the heart within the chest that is felt. In cases of isolated extrasystoles, the patient may actually perceive the augmented postextrasystolic beat as the “skipped” beat rather than the premature beat itself, probably because the extrasystole blocks the next sinus beat and allows longer ventricular filling and thus a higher stroke volume.

The clinical perception of cardiac phenomena is highly variable. Some patients are aware of virtually every premature ventricular beat, but others are unaware of even complex atrial or ventricular tachyarrhythmias. Awareness is heightened in sedentary, anxious, or depressed patients and reduced in active, happy patients. In some cases, palpitations are perceived in the absence of any abnormal cardiac activity.

Some patients simply have heightened awareness of normal cardiac activity, particularly when exercise, febrile illness, or anxiety increases heart rate. However, diligent evaluation for arrhythmia as the cause of palpitations is warranted. Arrhythmias range from benign to life threatening.

The most common arrhythmias include

Both of these arrhythmias usually are harmless.

Other common arrhythmias include

Bradyarrhythmias rarely cause a complaint of palpitations although some patients are aware of the slow rate.

Some arrhythmias (eg, PACs, PVCs, PSVT) often occur spontaneously in patients without serious underlying disorders, but others are often caused by a serious cardiac disorder.

Serious cardiac causes include myocardial ischemia Overview of Acute Coronary Syndromes (ACS) Acute coronary syndromes result from acute obstruction of a coronary artery. Consequences depend on degree and location of obstruction and range from unstable angina to non–ST-segment elevation... read more or other myocardial disorders, congenital heart disease (eg, Brugada syndrome, arrhythmogenic right ventricular cardiomyopathy, congenital long QT syndrome Long QT Syndrome and Torsades de Pointes Ventricular Tachycardia Torsades de pointes is a specific form of polymorphic ventricular tachycardia in patients with a long QT interval. It is characterized by rapid, irregular QRS complexes, which appear to be twisting... read more ), valvular heart disease Overview of Cardiac Valvular Disorders Any heart valve can become stenotic or insufficient (also termed regurgitant or incompetent), causing hemodynamic changes long before symptoms. Most often, valvular stenosis or insufficiency... read more , and conduction system disturbances (eg, disturbances that cause bradycardia or heart block Atrioventricular Block Atrioventricular (AV) block is partial or complete interruption of impulse transmission from the atria to the ventricles. The most common cause is idiopathic fibrosis and sclerosis of the conduction... read more ). Patients with orthostatic hypotension Orthostatic Hypotension Orthostatic (postural) hypotension is an excessive fall in blood pressure (BP) when an upright position is assumed. The consensus definition is a drop of > 20 mm Hg systolic, 10 mm Hg diastolic... read more commonly sense palpitations caused by sinus tachycardia upon standing.

Noncardiac disorders that increase myocardial contractility (eg, thyrotoxicosis, pheochromocytoma Pheochromocytoma A pheochromocytoma is a catecholamine-secreting tumor of chromaffin cells typically located in the adrenals. It causes persistent or paroxysmal hypertension. Diagnosis is by measuring catecholamine... read more , anxiety) may cause palpitations.

Some drugs, including digitalis, caffeine, alcohol, nicotine, and sympathomimetics (eg, albuterol, amphetamines, cocaine, dobutamine, epinephrine, ephedrine, isoproterenol, norepinephrine, and theophylline), frequently cause or exacerbate palpitations.

Metabolic disturbances, including anemia Evaluation of Anemia Anemia is a decrease in the number of red blood cells (RBCs—as measured by the red cell count, the hematocrit, or the red cell hemoglobin content). In men, anemia is defined as hemoglobin <... read more , hypoxia, hypovolemia, and electrolyte abnormalities (eg, diuretic-induced hypokalemia Hypokalemia Hypokalemia is serum potassium concentration 3.5 mEq/L ( 3.5 mmol/L) caused by a deficit in total body potassium stores or abnormal movement of potassium into cells. The most common cause is... read more ), can trigger or exacerbate palpitations.

Many arrhythmias that cause palpitations have no adverse physiologic consequences of their own (ie, independent of the underlying disorder). However, bradyarrhythmias, tachyarrhythmias, and heart blocks can be unpredictable and may adversely affect cardiac output and cause hypotension or death. Ventricular tachycardia Ventricular Tachycardia (VT) Ventricular tachycardia is ≥ 3 consecutive ventricular beats at a rate ≥ 120 beats/minute. Symptoms depend on duration and vary from none to palpitations to hemodynamic collapse and death. Diagnosis... read more sometimes degenerates to ventricular fibrillation Ventricular Fibrillation (VF) Ventricular fibrillation causes uncoordinated quivering of the ventricle with no useful contractions. It causes immediate syncope and death within minutes. Treatment is with cardiopulmonary... read more .

A complete history and physical examination are essential. Observations by other medical personnel or reliable observers should be sought.

History of present illness should cover the frequency and duration of palpitations and provoking or exacerbating factors (eg, emotional distress, activity, change in position, intake of caffeine or other drugs). Important associated symptoms include syncope, light-headedness, tunnel vision, dyspnea, and chest pain. Asking the patient to tap out the rate and cadence of palpitations is better than a verbal description and often allows a definitive diagnosis, as in the “missed beat” of atrial or ventricular extrasystoles or the rapid total irregularity of atrial fibrillation.

Review of systems should cover symptoms of causative disorders, including heat intolerance, weight loss, and tremor (hyperthyroidism Hyperthyroidism Hyperthyroidism is characterized by hypermetabolism and elevated serum levels of free thyroid hormones. Symptoms are many and include tachycardia, fatigue, weight loss, nervousness, and tremor... read more ); chest pain and dyspnea on exertion (myocardial ischemia Overview of Coronary Artery Disease Coronary artery disease (CAD) involves impairment of blood flow through the coronary arteries, most commonly by atheromas. Clinical presentations include silent ischemia, angina pectoris, acute... read more ); and fatigue, weakness, heavy vaginal bleeding, and dark tar-like stools (anemia Iron Deficiency Anemia Iron deficiency is the most common cause of anemia and usually results from blood loss; malabsorption, such as with celiac disease, is a much less common cause. Symptoms are usually nonspecific... read more ).

Past medical history should identify known potential causes, including documented arrhythmias and heart or thyroid disorders. Family history should note occurrences of syncope (sometimes mistakenly described as seizures) or sudden death at an early age.

The drug profile should be reviewed for offending prescription drugs (eg, antiarrhythmics, digoxin, beta-agonists, theophylline, and rate-limiting drugs); over-the-counter drugs (eg, cold and sinus drugs, dietary supplements containing stimulants), including alternative medicines; and illicit drugs (eg, cocaine, methamphetamines). Caffeine (eg, coffee, tea, numerous soft drinks and energy drinks), alcohol, and tobacco use should be determined.

The general examination should note whether an anxious demeanor or psychomotor agitation is present. Vital signs are reviewed for fever, hypertension, hypotension, tachycardia, bradycardia, tachypnea, and low oxygen saturation. Orthostatic changes in blood pressure (BP) and heart rate should be measured.

Examination of the head and neck should note any abnormality or dyssynchrony of the jugular pulse waves compared with the carotid pulse or auscultated heart rhythm and findings of hyperthyroidism, such as thyroid enlargement or tenderness and exophthalmos. The conjunctivae, palmar creases, and buccal mucosa should be inspected for pallor.

Cardiac auscultation should note the rate and regularity of the rhythm as well as any murmurs or extra heart sounds that might indicate underlying valvular or structural heart disease.

Neurologic examination should note whether resting tremors or brisk reflexes are present (suggesting excess sympathetic stimulation). An abnormal neurologic finding suggests that seizures rather than a cardiac disorder may be the cause if syncope is one of the symptoms.

Certain findings suggest a more serious etiology:

Light-headedness or syncope Syncope Syncope is a sudden, brief loss of consciousness with loss of postural tone followed by spontaneous revival. The patient is motionless and limp and usually has cool extremities, a weak pulse... read more (particularly if injury occurs from syncope)
Chest pain Chest Pain Chest pain is a very common complaint. Many patients are well aware that it is a warning of potential life-threatening disorders and seek evaluation for minimal symptoms. Other patients, including... read more
Dyspnea
New onset of irregularly irregular heart rhythm
Heart rate >120 beats/minute or < 45 beats/minute while at rest
Significant underlying heart disease
Family history of recurrent syncope or sudden death
Exercise-induced palpitations or, particularly, syncope

History (see table Suggestive Historical Findings in Patients With Palpitations Suggestive Historical Findings in Patients With Palpitations ) and, to a lesser extent, physical examination provide clues to the diagnosis.

Palpation of the arterial pulse and cardiac auscultation may reveal a rhythm disturbance. However, the examination is not always diagnostic of a specific rhythm, except when it identifies the unique irregular irregularity of some cases of rapid atrial fibrillation, the regular irregularity of coupled atrial or ventricular extrasystoles, the regular tachycardia at 150 beats/minute of PSVT, and the regular bradycardia of < 35 beats/minute of complete atrioventricular block.

Careful examination of the jugular venous pulse waves simultaneously with cardiac auscultation and palpation of the carotid artery allows evaluation of atrial rhythm through jugular waves while the auscultated sounds or the pulse in the carotids are the product of ventricular contraction.

Thyroid enlargement or tenderness with exophthalmos suggests thyrotoxicosis. Marked hypertension and regular tachycardia suggest pheochromocytoma.

Testing typically is done.

ECG, sometimes with ambulatory monitoring
Laboratory testing
Sometimes imaging studies, stress testing, or both

ECG is done, but unless the recording is done while symptoms are occurring, it may not provide a diagnosis. Many cardiac arrhythmias are intermittent and show no fixed ECG abnormalities; exceptions include

If no diagnosis is apparent and symptoms are frequent, Holter monitoring Holter monitor The standard electrocardiogram (ECG) provides 12 different vector views of the heart’s electrical activity as reflected by electrical potential differences between positive and negative electrodes... read more for 24 to 48 hours is useful; for intermittent symptoms, an event recorder worn for longer periods and activated by the patient when symptoms are felt is better. These tests are used mainly when a sustained arrhythmia is suspected, rather than when symptoms suggest only occasional skipped beats. Patients with very infrequent symptoms that clinicians suspect represent a serious arrhythmia may have a device implanted beneath the skin of the upper chest. This device, often called a loop recorder, continuously records the rhythm and can be interrogated by an external machine that allows the cardiac rhythm to be printed. Finally, a variety of commercially available products that patients may be using may provide additional useful information. These products include fitness trackers, which monitor heart rate, and mobile ECG monitors that are available for phones and watches.

Laboratory testing is needed in all patients. All patients should have a complete blood count and measurement of serum electrolytes, including magnesium and calcium. Further testing should be aimed at suspected causes. The cardiac marker troponin should be measured in patients with ongoing arrhythmias, chest discomfort, or other symptoms suggesting active or recent coronary ischemia, myocarditis, or pericarditis.

Thyroid function tests are indicated when atrial fibrillation is newly diagnosed or there are symptoms of hyperthyroidism. Patients with paroxysms of high BP should be evaluated for pheochromocytoma.

Sometimes tilt-table testing Tilt Table Testing Tilt table testing is used to evaluate syncope in Younger, apparently healthy patients Elderly patients when cardiac and other tests have not provided a diagnosis Tilt table testing produces... read more is done in patients with postural syncope.

Imaging is sometimes needed. Patients with newly diagnosed arrhythmia, findings suggesting cardiac dysfunction or findings suggesting structural heart disease require echocardiography Echocardiography This photo shows a patient having echocardiography. This image shows all 4 cardiac chambers and the tricupsid and mitral valves. Echocardiography uses ultrasound waves to produce an image of... read more and sometimes cardiac MRI MRI Cardiac imaging tests can delineate cardiac structure and function. Standard imaging tests include Echocardiography Chest x-ray CT MRI read more . Patients with symptoms on exertion require stress testing sometimes with stress echocardiography Stress Testing In stress testing, the heart is monitored by electrocardiography (ECG) and often imaging studies during an induced episode of increased cardiac demand so that ischemic areas potentially at risk... read more , nuclear scanning Radionuclide Imaging of the Heart Radionuclide imaging uses a special detector (gamma camera) to create an image following injection of radioactive material. This test is done to evaluate Cardiac valvular disorders Cardiomyopathy... read more , or PET Positron emission tomography (PET) Cardiac imaging tests can delineate cardiac structure and function. Standard imaging tests include Echocardiography Chest x-ray CT MRI read more .

Precipitating drugs and substances that can cause syncope Some Drug Causes of Syncope are stopped. If dangerous or debilitating arrhythmias are caused by a necessary therapeutic drug, a different drug should be tried.

For isolated PACs and PVCs in patients without structural heart disease, simple reassurance is appropriate. For otherwise healthy patients in whom these phenomena are disabling, a beta-blocker can be given provided efforts are made to avoid reinforcing the perception by anxious patients that they have a serious disorder.

Identified rhythm disturbances and underlying disorders are investigated and treated (see table Some Treatments for Arrhythmias Some Treatments for Arrhythmias ).

Older patients are at particular risk of adverse effects of antiarrhythmics; reasons include lower glomerular filtration rate and concomitant use of other drugs. When drug treatment is needed, lower doses should be used to start. Subclinical conduction abnormalities may be present (recognized on ECG or other studies), which might worsen with use of antiarrhythmics; such patients may require a pacemaker to allow the use of antiarrhythmics.

Palpitations are a frequent but relatively nonspecific symptom.
Palpitations are not a reliable indicator of a significant arrhythmia, but palpitations in a patient with structural heart disease or an abnormal ECG may be a sign of a serious problem and warrant investigation.
An ECG or other recording done during symptoms is essential; a normal ECG in a symptom-free interval does not rule out significant disease.
Most antiarrhythmics themselves can cause arrhythmias.
If in doubt about a rapid tachyarrhythmia in a patient in hemodynamic distress, cardiovert first and ask questions later.