Electrocardiographic changes following exercise in the congenitally deaf school children: relationship with Jervell Lange Neilsen syndrome (the Long QT syndrome).
The present study was conducted to test the effects of exercise stress on the ECG of the congenitally deaf children from school for deaf, in view of the occurrence of the Jervell-Lange Neilsen (Surdo Cardiac) variant of the Long QT Syndrome (LQTS) in them. An ECG Lead II was recorded at rest and after two minutes of static jogging. For comparison, the same protocol was repeated in normal healthy children from another school. ECG were analysed for the calculation of corrected QT interval (QTc) by Bazett's equation QTc = QT/square root of R-R and also for the evidence for other abnormalities. Both in the normal and deaf children, exercise did not produce significant (P > 0.05) change in QTc from their resting values. However, when pre and post exercise QTc values of deaf children were compared with normal children, the female deaf had significantly longer QTc (P < 0.01) both at rest and after exercise than normal female children. Normal children did not show significant ECG abnormality either at rest or on exercise. On the contrary many of their counter part (deaf) exhibited occasional ECG abnormality at rest but plethora of abnormalities after exercise viz., sinus arrhythmias, sinus pauses, ST depression, T-inversion, biphasic-T, notched-T, T-alternans, nodal ectopics and junctional rhythm. These results lend credence to the hypothesis of sympathetic imbalance and repolarisation defects in deaf children's heart, which in more severe form could pass into frank Jervell-Lange Neilsen variant of the Long: QT Syndrome.