Second Order Approximation of Heart Rate Turbulence after an Isolated Pre-Ventricular Contraction (PVC)

The human heart is usually a well synchronized system where certain muscle groups contract and relax at prescribed intervals. Serious cardiac problems can occur when these muscle groups do not contract, or relax, in the proper sequence. One of these ill-timed contractions, called a Pre-Ventricular Contraction (PVC), occurs when the electrical activity is initiated in a ventricle causing it to contract prematurely. The occurrence of a single isolated beat is not uncommon even in healthy subjects; however heart-rate turbulence (the after effects of a PVC) has been shown to be a powerful Electrocardiographic arrhythmia related risk predictor. The predictive value of Heart Rate Turbulence (HRT) is comparable with that of the ejection fraction of the left ventricle 1 . Heart Rate Turbulence is the physiological, bi-phasic response of the sinus node to premature ventricular contractions. 1