Heart rhythm : the official journal of the Heart Rhythm Society
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Comparative Study
Causes of ventricular oversensing in implantable cardioverter-defibrillators: implications for diagnosis of lead fracture.
Implantable cardioverter-defibrillator (ICD) ventricular oversensing may result in inappropriate therapy, which may be triggered by lead/connection issues that require surgical revision or physiologic oversensing that may be resolved with reprogramming. The sensing integrity counter (SIC) is an oversensing diagnostic that increments for very rapid ventricular intervals < or =130 ms. ⋯ Oversensing resulting in frequent, very short intervals typically are caused by either lead/connection issues or physiologic signals. The additional finding of rapid NSTs usually indicates a lead/connection issue, even in the absence of impedance abnormalities.
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The presence of J waves on ECGs is related to idiopathic ventricular fibrillation (VF). ⋯ Idiopathic VF patients with J waves had a high incidence of LP showing circadian variation with night ascendancy. J waves may be more closely associated with depolarization abnormality and autonomic modulation than with repolarization abnormality.