What could be causing sharp and sudden aware heart beats, also known as palpitations, occurring 10 times an hour in an adult, potentially related to anxiety, stress, dehydration, or underlying heart conditions such as arrhythmias or cardiomyopathy?

Causes of Sharp and Sudden Aware Heart Beats (Palpitations) Occurring 10 Times Per Hour

Sharp, sudden awareness of heartbeats occurring 10 times per hour most commonly represents premature ventricular contractions (PVCs) or premature atrial contractions (PACs), which are typically described as skipped beats followed by a strong compensatory beat, and require systematic evaluation to exclude underlying structural heart disease, arrhythmias, or reversible triggers. 1

Primary Cardiac Causes

Premature Beats (Most Common)

• Premature ventricular contractions (PVCs) and premature atrial contractions (PACs) are the most frequent cause of intermittent palpitations described as "skipped" or extra beats followed by a strong heartbeat 1
• These are commonly described as pauses or irregularities in heart rhythm, with patients reporting the sensation of a forceful beat after the pause 1
• PVCs can occur in patterns of bigeminy or trigeminy, creating regular patterns of premature beats 1

Ventricular Arrhythmias

• Nonsustained ventricular tachycardia can present as brief episodes of rapid, regular palpitations 1
• Ventricular arrhythmias may be triggered by exercise or emotional stress, particularly in patients with underlying structural heart disease 1
• Delayed afterdepolarizations can trigger ventricular arrhythmias, especially in the setting of heart failure or digoxin toxicity 1

Supraventricular Arrhythmias

• Paroxysmal supraventricular tachycardia (PSVT) presents with sudden onset and termination of regular, rapid palpitations 1, 2
• Atrial fibrillation causes irregular palpitations and occurs frequently, though typically at higher rates than 10 episodes per hour 1
• Atrial flutter may present with regular or irregular palpitations depending on AV conduction 1

Underlying Structural Heart Disease to Evaluate

Coronary Artery Disease

• Ischemic heart disease is a critical cause of ventricular arrhythmias and must be excluded 1
• Coronary spasm can trigger polymorphic ventricular tachycardia and palpitations 3

Valvular Heart Disease

• Mitral valve prolapse is commonly associated with palpitations and can trigger ventricular arrhythmias 1, 4
• Aortic stenosis and mitral regurgitation may be associated with heart failure and ventricular arrhythmias 1

Cardiomyopathies

• Hypertrophic cardiomyopathy, dilated cardiomyopathy, and arrhythmogenic right ventricular cardiomyopathy all predispose to ventricular arrhythmias 1
• Tachycardia-mediated cardiomyopathy can develop from persistent supraventricular tachycardia over weeks to months 1, 2, 5

Reversible and Precipitating Factors

Medications and Substances

• QT-prolonging medications can cause torsades de pointes and ventricular arrhythmias (check www.crediblemeds.org) 1
• Stimulants including cocaine, amphetamines, and over-the-counter supplements can provoke arrhythmias 1
• Antiarrhythmic medications themselves can be proarrhythmic 1
• Digoxin toxicity causes delayed afterdepolarizations and triggered ventricular arrhythmias 1

Metabolic and Systemic Conditions

• Electrolyte abnormalities (particularly potassium, magnesium, calcium) are critical reversible causes 1
• Thyroid disease (hyperthyroidism) commonly causes palpitations and arrhythmias 1
• Acute or chronic kidney disease affects electrolyte balance and arrhythmia risk 1
• Dehydration and volume depletion can trigger arrhythmias 6

Autonomic and Physiologic Triggers

• Emotional stress and anxiety are common triggers, with vagal or adrenergic predominance affecting arrhythmia type 1
• Exercise can precipitate ventricular arrhythmias, particularly in structural heart disease or channelopathies 1
• Sinus tachycardia from physiologic stress (fever, infection, volume loss) must be distinguished from primary arrhythmias 1

Genetic and Familial Considerations

Cardiac Channelopathies

• Long QT syndrome, Brugada syndrome, short QT syndrome, and catecholaminergic polymorphic ventricular tachycardia (CPVT) can all present with palpitations 1
• Family history of sudden cardiac death, unexplained drowning, or sudden infant death syndrome suggests inherited channelopathies 1

Familial Cardiomyopathies

• Family history of hypertrophic, dilated, or arrhythmogenic right ventricular cardiomyopathy increases risk 1
• Neuromuscular diseases (muscular dystrophy) can be associated with cardiomyopathies 1

Critical Red Flags Requiring Urgent Evaluation

The following features indicate potentially life-threatening arrhythmias requiring immediate assessment:

• Syncope or near-syncope associated with palpitations suggests hemodynamically significant arrhythmia 1, 2
• Chest pain or dyspnea during palpitations may indicate myocardial ischemia or heart failure 1
• Family history of sudden cardiac death in first-degree relatives 1
• Known structural heart disease (any cardiomyopathy, significant valvular disease, congenital heart disease) 1, 2
• Palpitations triggered by exercise raise concern for catecholaminergic arrhythmias or ischemia 1

Diagnostic Approach

Essential Initial Evaluation

• 12-lead ECG is mandatory to assess for structural abnormalities, pre-excitation (Wolff-Parkinson-White), QT interval, and baseline rhythm 1
• Complete medication history including over-the-counter medications, supplements, and illicit drugs 1
• Physical examination focused on detecting structural heart disease: murmurs (especially midsystolic click of mitral valve prolapse), jugular venous distention, edema, carotid bruits 1

Ambulatory Monitoring Strategy

• Event monitors or continuous loop recorders are indicated when palpitations occur unpredictably, as with 10 episodes per hour 6
• 24-48 hour Holter monitoring may be appropriate if palpitations occur daily 6
• The goal is to correlate symptoms with documented rhythm 1, 6

Laboratory Assessment

• Thyroid function tests (TSH, free T4) 1
• Electrolytes (potassium, magnesium, calcium) 1
• Renal function (creatinine, eGFR) 1

Advanced Evaluation When Indicated

• Echocardiography to assess for structural heart disease, valvular abnormalities, and left ventricular function 1
• Exercise stress testing if palpitations are exercise-related 1
• Electrophysiology study is indicated for documented palpitations associated with syncope or inappropriately rapid pulse during symptoms 4

Common Pitfalls to Avoid

• Do not assume benign etiology without excluding structural heart disease, even in young patients 1
• Palpitations frequently occur during normal rhythm, so symptom correlation with documented arrhythmia is essential 1
• Effective bradycardia from frequent PVCs can result in inaccurate heart rate estimation and apical-radial pulse deficit 1
• Up to 16% of patients have no identifiable cause after thorough evaluation, but this is a diagnosis of exclusion 6
• Patients with pre-excitation on ECG (Wolff-Parkinson-White) require prompt electrophysiology referral due to risk of sudden death if atrial fibrillation develops with rapid ventricular response 2