Causes of Palpitations
Palpitations are most commonly caused by cardiac arrhythmias, anxiety disorders, or various non-cardiac conditions that affect heart rhythm. Understanding the underlying mechanisms is essential for proper diagnosis and management.
Definition and Characteristics
- Palpitations are defined as an unpleasant awareness of abnormal or irregular heartbeats, which may be described as pauses followed by strong beats or irregularities in heart rhythm 1, 2
- Patients may describe palpitations as regular or irregular, with sudden onset and termination (paroxysmal) or gradual onset and offset (non-paroxysmal) 1
Cardiac Causes
Arrhythmias
Premature beats: Commonly experienced as skipped beats or extra beats
Supraventricular tachycardias (SVTs):
- Atrioventricular nodal reentrant tachycardia (AVNRT) - characterized by sudden onset/offset 1
- Atrioventricular reciprocating tachycardia (AVRT) - often seen with Wolff-Parkinson-White syndrome 1, 3
- Atrial fibrillation (AF) - typically causes irregular palpitations 1, 2
- Atrial flutter 1
- Multifocal atrial tachycardia (MAT) - commonly associated with pulmonary disease 1
Ventricular arrhythmias:
Structural Heart Disease
- Cardiomyopathy 3
- Valvular heart disease, particularly mitral valve prolapse 3, 2
- Coronary artery disease 3
- Congestive heart failure 2
- Pericarditis 2
Non-Cardiac Causes
Endocrine/Metabolic
- Hyperthyroidism - common cause of persistent palpitations 2
- Hypoglycemia 2
- Electrolyte abnormalities 4
Neurological/Psychiatric
- Anxiety disorders - very common cause of palpitations 5, 2
- Panic disorder - characterized by palpitations, sweating, trembling, and fear 5
- Autonomic dysfunction 4
- Seizures with autonomic features (rare) 6
Physiological
Hormonal Factors
- Menstrual cycle variations (especially luteal phase) 3
- Pregnancy 3
- Perimenopausal period - related to increased sympathetic activity 3
Substance-Related
Pathophysiological Mechanisms
Cardiac Mechanisms
- Automaticity: Enhanced or abnormal pacemaker activity in cardiac cells 1
- Triggered activity: Disturbances in repolarization causing afterdepolarizations 1
- Re-entry: Most common arrhythmia mechanism - electrical impulse circulates around a fixed obstacle or through relatively refractory tissue 1
Neurological Mechanisms
- Cardioception: Awareness of heartbeat sensations, a subset of interoception 4
- Central nervous system involvement: Brain areas like the right insula, cingulate gyrus, and somatosensory cortices are implicated in heartbeat detection and palpitation perception 4
- Autonomic nervous system: Sympathetic activation can trigger or exacerbate palpitations 4
Warning Signs of Serious Conditions
- Palpitations accompanied by syncope or pre-syncope (dizziness) 1, 2
- Palpitations with chest pain 1
- Family history of sudden cardiac death 7
- Palpitations during exercise 1
- Palpitations with structural heart disease 3
Clinical Pearls
- Up to 16% of patients with palpitations may have no identifiable cause despite thorough investigation 2
- Very frequent PVCs (>10,000-20,000/day) can lead to PVC-induced cardiomyopathy, which is reversible with control of the PVCs 1
- Palpitations with sudden onset and termination are more likely to be due to reentrant tachycardias like AVNRT or AVRT 1
- Termination of palpitations with vagal maneuvers suggests involvement of AV nodal tissue 1
- Palpitations during pregnancy may be due to mechanical stimuli or potential arrhythmogenic effects of pregnancy 3
Understanding these various causes of palpitations helps guide appropriate diagnostic workup and management strategies to address both the symptom and its underlying cause.