Palpitation means an awareness of the heart beat. It is not therefore necessarily due to a heart rhythm abnormality. Palpitations are a common source of worry for children and their parents. A good history and an ECG will allow differentiation between the vast majority that are benign and the rare instances when they are the symptom of a life-threatening arrhythmia. Palpitations are rarely due to bradyarrhythmias as they usually present with syncope or exercise intolerance.
Worrying features in the history include:
Frequent or prolonged episodes
Structural heart disease - particularly those who have undergone a surgical repair are most at risk of life threatening arrhythmias.
Syncope - very rapid atrial arrhythmias or ventricular arrhythmias may cause low output states with dizziness, syncope and fits.
Precipitant factor - Hypertophic Cardiomyopathy (HCM) or Right Ventricular Arrhythmogenic Dysplasia (RVAD) may present with exercise induced arrhythmias or syncope. Those with LQTS may occur with sudden noise or temperature change (eg diving into pool).
Deafness may be part of the Long QT syndrome (LQTS) as the underlying biochemical defect also affects the cochlear.
Family history of sudden death (HCM, LQTS, RVAD)
The examination is usually normal. A mid systolic click and mitral regurgitant murmur may be present in mitral valve prolapse (MVP) but this is an exceptional disorder in childhood. It is helpful if the patient is experiencing palpitations at the time of the examination to assess the rate, whether the rhythm is regular or not and obtaining an ECG rhythm strip (limb leads only are acceptable although a 12 lead ECG is preferable) usually establishes the true cause.
In general a good history, examination and an ECG are sufficient to diagnose and reassure the majority. Symptoms need to be relatively frequent to capture with a monitor (eg 24 hr tape) but if they occur with exercise a treadmill test is very useful. Assessment of anaemia or thyroid status is unnecessary unless the history or examination is suspicious.
Normal or Benign Arrhythmias
This may be marked and the patient may notice the irregularity of the heart rate. Ascertaining that the heart rate varies with respiration is the key and the ECG is confirmatory.
This is mostly found with exercise and may be a source of concern to teenagers. Usually they are just aware of the normal physiological response to exercise. If there are no other symptoms or concerns and the ECG is normal then asking the patient to run around to reproduce the symptoms and then repeating the ECG may be all that is necessary for reassurance. Otherwise referral for a formal exercise test on a treadmill will be necessary to exclude more sinister causes.
Premature Atrial Contractions (PACs)
The QRS complex is narrow with a compensatory pause before the next beat which allows greater cardiac filling and thus a larger ejection volume for the next beat. The person notices the compensatory pause and interprets it as a missing a beat or the heart thumping in the chest. The third beat is the PAC followed by the compensatory pause.
Premature Ventricular Contractions (PVCs)
PVSs are have a broad QRS complex but otherwise they produce the same symptoms as PACs. Very frequent PVSs may occur which usually disappear with exercise if benign. In the strip the third beat is a PVC.