Early Repolarization Pattern Inheritance in the Cardiac Arrest Survivors With Preserved Ejection Fraction Registry (CASPER).

Objectives: This study explored early repolarization (ER) pattern inheritance between survivors of unexplained cardiac arrest (UCA) and their first-degree relatives.

Background: ER is considered a factor that confers an increased risk of sudden death. A monogenic explanation for ER is seldom evident after cascade screening.

The effects of an automatic, low pressure and constant flow ventilation device versus manual ventilation during cardiovascular resuscitation in a porcine model of cardiac arrest.

Background: Cardiac arrest is an important cause of mortality. Cardiopulmonary resuscitation (CPR) improves survival, however, delivery of effective CPR can be challenging and combining effective chest compressions with ventilation, while avoiding over-ventilation is difficult. We hypothesized that ventilation with a pneumatically powered, automatic ventilator (Oxylator(®)) can provide adequate ventilation in a model of cardiac arrest and improve the consistency of ventilations during CPR.

Usefulness of beta-blocker therapy and outcomes in patients with pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a disorder in which pulmonary arterial remodeling and vasoconstriction progressively lead to right heart failure (HF), exercise intolerance, and high mortality. Beta-blockers have been shown to decrease mortality in left-sided HF, but their efficacy in isolated right HF associated with PAH is uncertain. Patients with PAH may have cardiac co-morbidities for which β-blocker therapy is indicated, and the relative risk benefit of this therapy remains to be proved.

Effects of chronic gap junction conduction-enhancing antiarrhythmic peptide GAP-134 administration on experimental atrial fibrillation in dogs.

Background: Abnormal intercellular communication caused by connexin dysfunction may contribute to atrial fibrillation (AF). The present study assessed the effect of the gap junction conduction-enhancing antiarrhythmic peptide GAP-134 on AF inducibility and maintenance in a dog model of atrial cardiomyopathy.

Methods And Results: Twenty-four dogs subject to simultaneous atrioventricular pacing (220 bpm for 14 days) were randomly assigned to placebo treatment (PACED-CTRL; 12 dogs) or oral GAP-134 (2.

Influence of ventriculoatrial timing on hemodynamics and symptoms during supraventricular tachycardia.

Aims: Patients with reentrant supraventricular tachycardia (SVT) are often highly symptomatic and the mechanism of symptoms is not well understood. We hypothesized that variation in ventriculoatrial interval (QRS to P) modulates the left atrial pressure and symptoms during tachycardia.

Methods And Results: Three hundred twenty-six patients awaiting electrophysiological study completed a questionnaire regarding "neck pounding" or "shirt flapping" during tachycardia.

Experimental studies of atrial fibrillation: a comparison of two pacing models.

Rapid ventricular pacing (RVP) is a well-established animal model of atrial fibrillation (AF). However, this model is limited by a high mortality rate and severe heart failure. The purpose of our study was to assess a new canine model of inducible AF.

I(Ks) block by HMR 1556 lowers ventricular defibrillation threshold and reverses the repolarization shortening by isoproterenol without rate-dependence in rabbits.

Introduction: The slow delayed rectifier K+ current (I(Ks)) contributes little to ventricular repolarization at rest. It is unclear whether I(Ks) plays a role during ventricular fibrillation (VF) or ventricular repolarization at rapid rates during beta-adrenergic stimulation.

Methods And Results: In an in vivo rabbit model, we evaluated the effects of HMR 1556 (1 mg Kg(-1) + 1 mg kg(-1) hr(-1) i.

Effects of rotigaptide, a gap junction modifier, on defibrillation energy and resuscitation from cardiac arrest in rabbits.

The gap junction modifier Rotigaptide (ZP123), which promotes cellular coupling, was hypothesized to decrease defibrillation thresholds during prolonged ventricular fibrillation (VF). Thirty-two New Zealand white rabbits were randomized to receive saline (control, n = 16) or Rotigaptide (n = 16). Following 4 min of untreated VF, biphasic defibrillation shocks were applied through chest wall patches, starting either at 300 volts (V) (n = 16) or 500 V (n = 16), with 200 V increasing steps to 900 V in case of shock failure.

Blockade of IKs by HMR 1556 increases the reverse rate-dependence of refractoriness prolongation by dofetilide in isolated rabbit ventricles.

1. The rate-dependent contributions of the rapid and slow components of the cardiac delayed rectifier K+ current (IKr and IKs, respectively) to repolarization are not fully understood. It is unclear whether the addition of IKs block will attenuate reverse rate-dependence seen after IKr block.

Effects of flecainide on atrial and ventricular refractoriness in rabbits in vitro and in vivo.

This study compared the in vitro versus in vivo effects of flecainide on effective refractory period (ERP) in atrial and ventricular tissue in rabbits. Flecainide (a class 1c agent) was chosen, on the basis of its known pharmacological profile and antiarrhythmic actions, to provide a reference compound for investigating models that suitably predict the clinical effects of antiarrhythmics. The rabbit models used were those previously described by Lowe et al.

Effects of E4031 and quinidine on atrial and ventricular refractoriness in rabbits in vivo.

This study assessed the effects of E4031 and quinidine on refractoriness (ERP) in a new in vivo model in rabbits. Following sinoatrial (SAN) and atrioventricular node (AVN) ablation ERP was determined in atria and ventricles with the shortest S1-S2 interval eliciting a second electrogram defined as the ERP. The effects of E4031 and quinidine (dose ranges 1-8 micromol/kg) were compared.