High-rate pacing suppresses Torsade de Pointes arrhythmias and reduces spatial dispersion of repolarization in the chronic AV-block dog model.

An electrical storm of Torsade de Pointes arrhythmias (TdP) can be reproducibly induced in the anesthetized chronic AV-block (CAVB) dog by infusion of the I-blocker dofetilide. Earlier studies showed that these arrhythmias 1) arise from locations with high spatial dispersion in repolarization (SDR) and 2) can be suppressed by high-rate pacing. We examined whether suppression of TdP by high-rate pacing is established through a decrease in SDR in the CAVB dog.

Automatic measurement of short-term variability of repolarization to indicate ventricular arrhythmias in a porcine model of cardiac ischaemia.

Aims: An automated method for determination of short-term variability (STV) of repolarization on intracardiac electrograms (STV-ARIauto) has previously been developed for arrhythmic risk monitoring by cardiac implantable devices, and has proved effective in predicting ventricular arrhythmias (VA) and guiding preventive high-rate pacing (HRP) in a canine model. Current study aimed to assess (i) STV-ARIauto in relation to VA occurrence and secondarily (ii-a) to confirm the predictive capacity of STV from the QT interval and (ii-b) explore the effect of HRP on arrhythmic outcomes in a porcine model of acute myocardial infarction (MI).

Methods And Results: Myocardial infarction was induced in 15 pigs.

I Activator ML277 Mildly Affects Repolarization and Arrhythmic Outcome in the CAVB Dog Model.

Long QT syndrome type 1 with affected I is associated with a high risk for developing Torsade de Pointes (TdP) arrhythmias and eventually sudden cardiac death. Therefore, it is of high interest to explore drugs that target I as antiarrhythmics. We examined the antiarrhythmic effect of I channel activator ML277 in the chronic atrioventricular block (CAVB) dog model.

Remodeling in the AV block dog is essential for tolerating moderate treadmill activity.

Background: A preclinical model standardized at different remodeling stages after AV block induction in awake state is suitable for the evaluation of improved cardiac devices. We studied exercise-induced cardiorespiratory parameters at three different timepoints after inducing AV block in dogs.

Methods: Mongrel dogs (n = 12) were placed on a treadmill with a 10% incline and performed a moderate exercise protocol (10-minute run at 6 km/h).

Chronically altered ventricular activation causes pro-arrhythmic cardiac electrical remodelling in the chronic AV block dog model.

Aims: Altered ventricular activation (AVA) causes intraventricular mechanical dyssynchrony (MD) and impedes contraction, promoting pro-arrhythmic electrical remodelling in the chronic atrioventricular block (CAVB) dog. We aimed to study arrhythmogenic and electromechanical outcomes of different degrees of AVA.

Methods And Results: Following atrioventricular block, AVA was established through idioventricular rhythm (IVR; n = 29), right ventricular apex (RVA; n = 12) pacing or biventricular pacing [cardiac resynchronization therapy (CRT); n = 10].