Differential Diagnosis

Common Diagnoses

  • Anxiety (Increased Awareness of Normal Heartbeat)
  • Sinus Tachycardia (e.g. Stress, Fever, Exercise)
  • Atrial Ectopics
  • Ventricular Ectopics
  • Supraventricular Tachycardia (SVT)

Rare Diagnoses

  • Heart Block (Especially with Changes in Block)
  • Sick Sinus Syndrome
  • Drug Abuse
  • Ventricular Tachycardia (VT)
  • Phaeochromocytoma
  • Carcinoid Syndrome

Ready Reckoner

Key distinguishing features of the most common diagnoses

AnxietySinus TachycardiaAtrial EctopicsVentricular EctopicsSVT
Sudden OnsetPossibleNoPossiblePossibleYes
‘Heart Racing’YesYesNoNoYes
‘Heart Misses a Beat’PossibleNoYesYesNo
Underlying Beart DiseaseNoNoNoPossiblePossible
Rate/Rhythm Abnormal During EpisodeNoYesYesYesYes

Possible Investigations

Likely:ECG, TFT.

Possible:U&E, 24 h ECG or event monitor, Tilt table test.

Small Print:Echocardiography, further secondary care cardiac investigations, 24 h urinary 5-HIAA, 24 h urinary-free catecholamines and VMAs.

  • ECG: May show arrhythmia itself or evidence of ischaemic heart disease or Wolff– Parkinson–White syndrome.
  • TFT: Thyrotoxicosis can cause palpitations or exacerbate other causes.
  • U&E: Electrolyte disturbance can precipitate or aggravate some arrhythmias.
  • 24 h ECG or event monitor: To provide ECG evidence of the arrhythmia.
  • Echocardiography: To investigate possible structural lesions such as valvular problems or cardiomyopathy.
  • Further secondary care investigations: Might include investigation for underlying ischaemic heart disease.
  • 24 h urinary 5-HIAA: If carcinoid syndrome suspected.
  • 24 h urinary-free catecholamines and VMAs: If phaeochromocytoma suspected.
  • Tilt table test: if suspicion of PoTS

Top Tips

  • Take time to obtain a clear history, as the patient’s perception of a ‘palpitation’ may differ markedly from yours.
  • In paroxysmal cases, suggest that the patient attends the surgery or casualty urgently during an attack to obtain an ECG.
  • Patients can easily be taught to take their own pulse. Self-reported pulse rates can help considerably in establishing a diagnosis or they can measure their pulse using one of the various pieces of electronic gadgetry available for domestic use, though beware of fuelling neurosis.
  • Most patients with palpitations fear heart disease, and this anxiety exacerbates the symptoms. Ensure this fear is resolved whenever possible.

Red Flags

  • Multiple, or multifocal, ventricular ectopics suggest significant ischaemic heart disease – and may herald VT or fibrillation if they follow an infarct.
  • Sudden onset of tachycardia in a young adult with breathlessness, dizziness, chest pain and polyuria suggests significant SVT.
  • Take very seriously patients with palpitations which are linked with syncope, or which come on after exercise, or who have an existing cardiac history, or who have a family history of sudden death in under 40s. All need referral.
  • Remember that digoxin can aggravate as well as resolve some arrhythmias.
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