Introduction Data on the behavior of the T wave during exercise in children is lacking. We evaluated the influence of exercise on T wave amplitude in normal children and a cohort with congenital 3rd degree heart block (CHB).
Methods 20 healthy children, median age 9.9 years (range 5.05–14.9 years), and 8 with CHB and escape junctional rhythm (structurally normal heart) median age 8,2 years (range 5–12 years) underwent maximum graded physical exercise. A 12 lead ECG was recorded at baseline, maximum exercise, one, two, four, and six minutes post-exercise. For each ECG, T amplitude was measured in lead II and praecordial leads, heart rate was calculated. Descriptive and analytical statistics were calculated, significance set at p = <0,05.
Results Normal children undergo changes in T wave amplitude, from rest 0,45+0,17 mV to significant increase 2 minutes post exercise 1,03+0,31 mV, most pronounced in lead V4. CHB patients have higher resting T wave amplitude 0,73+0,4 mV which similarly increases significantly 2 minutes post-exercise 1,97+0,68 mV. During exercise, R wave amplitude does not significantly alter.
Conclusions Exercise is associated with an abrupt increase in T wave amplitude 1 to 2 minutes post-exercise particularly in lateral praecordial leads. CHB patients have significantly raised resting T wave amplitude which further abruptly increases 1 to 2 minutes post-exercise. This repolarisation phenomenon during exercise has not previously been described. CHB patients have altered resting repolarisation gradients.