Pediatric Exercise Testing

Discussion on pediatric exercise testing.
Pediatric exercise testing may be used for evaluation of various disorders of cardiac rhythm rather than for inducible ischemia as in adults.
In a child with suspected sinus node dysfunction, chronotropic incompetence from sinus node dysfunction can be assessed by exercise testing.
Evaluation of escape rates and ventricular ectopy with exercise in complete heart block is an important aspect in the evaluation of congenital complete heart block.
ECG showing congenital complete heart block with ventricular rate of 47/min and atrial rate of 63/min.
In stage I of Bruce protocol, the atrial rate has increased to 100/min and ventricular rate to 60/min.
Tracing at peak exercise shows an atrial rate of 150/min and ventricular rate of 83/min. Increase in artefacts is visible on comparing the raw rhythm at the bottom of the image.
Response of accessory pathway conduction to exercise gives useful information on the rate at which anterograde preexcitation is blocked.
This measurement has been correlated with those made at electrophysiology study and may predict the potential risk of rapid anterograde conduction if the person develops atrial fibrillation.
If the preexcitation disappears in response to exercise, it can be assumed that they have a relatively low risk for atrial fibrillation with very rapid ventricular rates due to preexcitation.
QT prolongation and the occurrence of ventricular arrhythmias with exercise are another important aspect of exercise testing in children.
Though the QT interval should shorten with exercise, it may not do so in some of the congenital long QT syndromes.
Ventricular arrhythmias during exercise can be documented in congenital long QT syndromes as well as in catecholaminergic polymorphic ventricular tachycardia.
An ECG showing exercise induced monomorphic ventricular tachycardia
Tracing during recovery showing that the tachycardia has subsided, but ventricular ectopics are occurring in a trigeminal pattern with an R on T phenomenon.
Bidirectional ventricular tachycardia is the classical arrhythmia noted in catecholaminergic polymorphic ventricular tachycardia. Tracing shows bidirectional ventricular ectopics.
Though treadmill exercise produces higher peak heart rates, better quality electrocardiograms can be recorded with bicycle exercise because of lesser body motion which could produce baseline shifts and other artifacts.
Maximal oxygen uptake is about 10% higher with treadmill exercise than a bicycle ergometer. An advantage of treadmill is that most people are familiar with walking or running, including young children.
But exercise on a treadmill is not a natural form of walking or running for a person not familiar with exercise on a moving surface. Hence time for practice on the treadmill should be provided before testing.