A Novel Methodology for Assessing the Bounded-Input Bounded-Output Instability in QT Interval Dynamics: Application to Clinical ECG With Ventricular Tachycardia

• Published in: IEEE transactions on biomedical engineering Vol. 59; no. 8; pp. 2111 - 2117
• Main Authors: Chen , Xiaozhong, Trayanova, Natalia A.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.08.2012; Institute of Electrical and Electronics Engineers
• Subjects: Action Potentials; Aged; Algorithms; Biological and medical sciences; Bounded-input bounded-output (BIBO) stability; Cardiac dysrhythmias; Cardiology. Vascular system; Computerized, statistical medical data processing and models in biomedicine; ECG; Electrocardiography; Electrocardiography - methods; Electrocardiography. Vectocardiography; Electrodiagnosis. Electric activity recording; Equations; Female; Heart; History; Humans; Investigative techniques, diagnostic techniques (general aspects); Male; Mathematical model; Medical management aid. Diagnosis aid; Medical sciences; Middle Aged; Models, Cardiovascular; Poles and zeros; QT interval (QTI); Rail to rail inputs; repolarization dynamics; Signal Processing, Computer-Assisted; Stability analysis; Tachycardia, Ventricular - physiopathology; ventricular tachycardia (VT); Repolarization; QT interval (QTI); Arrhythmia; ECG; repolarization dynamics; Cardiovascular disease; Ventricular tachycardia; ventricular tachycardia (VT); Electrodiagnosis; Heart disease; Bounded-input bounded-output (BIBO) stability; BIBO system; Electrocardiography; Instability; Biomedical engineering
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/TBME.2011.2170837

The goal of this paper is to present a new methodology for assessing the bounded-input bounded-output (BIBO) stability in QT interval (QTI) dynamics from clinical ECG. The ECG recordings were collected from 15 patients who experienced ventricular tachycardia (VT). Ten-minute-long ECG recordings extracted immediately before the onset of a chosen VT, one per patient, were assembled into a VT group, while the control group comprised 10-min-long ECGs extracted 1 h before VT onset and at least 1 h after any prior arrhythmic event. Each 10-min recording was subdivided into 1-min ECG recordings (minECGs). The QTI dynamics of each minECG was defined as a function of several prior QTIs and RR intervals; the BIBO stability of this function was then assessed in the z-domain. The number of minECGs with unstable QTI dynamics (N us ) and the frequency of premature activations (PA), f PA , were counted for each ECG recording and were compared between the VT and control groups. The results show that the present methodology successfully captured the instability in QTI dynamics leading to VT onset in the studied population. Significantly larger N us was found in the VT group compared against the control and a positive correlation between N us and f PA was identified in both groups.