Beat-by-Beat Variability of QT ECG-Interval Holds a Well-Founded Promise for Clinical Cardiology: A Review

摘要

The advent of reliable software access to beat-by-beat QT interval series opened a novel insight to sympathetic control of ventricular myocardium. Experimental measurement of time constant in the RR-QT system (τ_(QT)) using pharmacological or electrophysiological manipulations of heart rate (HR) has documented that τ_(QT) size may introduce in borderline subjects in normal life settings episodes of functional long-QT syndrome. In type I young diabetics in the earliest phase of autonomic dysfunction, spectral QT and RR analyses suggest preferential vagal down-regulation but preservation of sympathetic re sponsiveness of ventricles to life challenges. Both findings signal an early risk worth to be dealt with by specific preventive steps.