The mother (III, 2; Figure 1 A) of the siblings had a normal ECG and no family history of heart disease or sudden death. Electrophysiological Study Electrophysiological study was performed in patients 1 and 2. [doi.org]

[…] periodic paralysis Isolated NADH-CoQ reductase deficiency 17p13.3 microduplication syndrome Distal 17p13.3 microdeletion syndrome Miller-Dieker syndrome Autosomal dominant hypohidrotic ectodermal dysplasia Benign familial infantile seizures Benign familial neonatal [csbg.cnb.csic.es]

Several nocturnal seizure-like motions of the patient followed by sudden awakening with palpitations have been reported [12]. 3. [doi.org]

A, Patient 1 (IV, 3): sinus rhythm, heart rate 52 beats per minute (bpm); left-axis deviation, QT 280 ms. B, Patient 2 (IV, 2): sinus rhythm, heart rate 96 bpm; left-axis deviation, QT 220 ms. [doi.org]

U wave can be observed, separated by an isoelectric T–U segment. 14 Longer T peak – T end interval may be observed, suggestive of augmented transmural dispersion of refractoriness. 15 Depression of the PQ segment, due to a heterogeneous abbreviation [doi.org]

The resting ECG is unremarkable, except for sinus bradycardia and prominent U waves in some patients. The most typical arrhythmia of CPVT is bidirectional ventricular tachycardia presenting with an alternating QRS axis. [circ.ahajournals.org]