The assessment of arrhythmic risk and arrhythmic substrate in patients with a manifest or concealed accessory pathway
2017-02-23T23:14:47Z (GMT) by
The thesis presents the arrhythmic risk as part of the natural history in asymptomatic patients with a manifest atrio-ventricular accessory pathway (i.e., Wolff-Parkinson-White electrocardiogram pattern) highlighting the ongoing controversy pertaining to the invasive electrophysiological management of these asymptomatic patients. The thesis argues against population screening or routine invasive testing with a view to catheter ablation based on the meta-analysis research presented which demonstrates the low mortality/morbidity rates in asymptomatic patients. The presented low mortality and morbidity along with the potential for harm by screening and subsequent testing, low sensitivity and specificity of risk stratifiers, practicality, cost-effectiveness and the potential for complications from electrophysiology study and ablation and even mortality that can mitigate benefit if undertaken routinely population wide is elaborated to justify current clinical practice and clinical guidelines. Additionally the thesis presents novel intra-cardiac electrophysiological measures for arrhythmic substrate assessment in patients with a suspected concealed septal atrio-ventricular accessory pathway. The widely utilized intra-cardiac pacing maneuver, the para-Hisian pacing maneuver is investigated demonstrating short stimulus-to-atrial intervals to reliably indicate inadvertent atrial capture to avoid technical and interpretative pitfalls. A critical change of stimulus-to- atrial interval using a small catheter adjustment to deliberately lose and obtain atrial capture reliably ensures that inadvertent atrial capture can be identified to avoid interpretative pitfalls. Additionally to overcome the limitation of requiring sustained supra-ventricular tachycardia for the utility of the widely used post entrainment measures, the first tachycardia cycle after supra-ventricular tachycardia induction with right ventricular extra stimulation is demonstrated to yield comparable information to entrainment, precluding the need for sustained supra-ventricular tachycardia, providing a unique maneuver and measures that both diagnose the supra-ventricular tachycardia substrate and mechanism when tachycardia is not sustained.