Clinical perception of effectiveness of virtual appointments and comparison with appointment outcomes at a specialist children's hospital.

Introduction: A transition from face-to-face to virtual consultations occurred in response to the COVID-19 pandemic. Evaluation of outcome data is essential for future healthcare modelling.

Methods: Clinicians at a children's hospital evaluated perceptions of face-to-face video and telephone appointments by questionnaire.

Optimal Implantable Cardioverter Defibrillator Programming.

Optimal programming of implantable cardioverter defibrillators (ICDs) is essential to appropriately treat ventricular tachyarrhythmias and to avoid unnecessary and inappropriate shocks. There have been a series of large clinical trials evaluating tailored programming of ICDs. We reviewed the clinical trials evaluating ICD therapies and detection, and the consensus statement on ICD programming.

Mechanism-specific effects of adenosine on ventricular tachycardia.

Introduction: There is no universally accepted method by which to diagnose clinical ventricular tachycardia (VT) due to cAMP-mediated triggered activity. Based on cellular and clinical data, adenosine termination of VT is thought to be consistent with a diagnosis of triggered activity. However, a major gap in evidence mitigates the validity of this proposal, namely, defining the specificity of adenosine response in well-delineated reentrant VT circuits.

A left ventricular epicardial to right ventricular endocardial dominant frequency gradient exists in human ventricular fibrillation.

Purpose: We hypothesized that in patients with left ventricular dysfunction undergoing implant of a biventricular ICD, the local dominant frequency during early induced ventricular fibrillation would be higher at an epicardial left ventricular position compared to an endocardial right ventricular position.

Methods: Patients undergoing implant of a biventricular ICD were studied. During ventricular fibrillation induction, bipolar electrograms were recorded from leads at an epicardial left ventricular position and an endocardial right ventricular position.

Strength duration curve for left ventricular epicardial stimulation in patients undergoing cardiac resynchronization therapy.

Introduction: The strength duration curve has been studied for right ventricular endocardial stimulation. There are differences between left ventricular epicardial and right ventricular endocardial stimulation due to different electrophysiologic properties and different electrode-tissue interface. The strength duration curve for epicardial left ventricular stimulation has not been studied so far.

ICD implantation and arrhythmia-free survival in patients with depressed LV function following surgery for valvular heart disease.

Background: Although prophylactic implantable cardioverter-defibrillator (ICD) implantation is beneficial in patients with severe ischemic cardiomyopathy, it is unclear whether patients with cardiomyopathy due to valvular heart disease have a similar benefit.

Methods: We followed 17 patients (14 men/three women, age 62 +/- 13 years, left ventricular ejection fraction [LVEF] 29 +/- 10%) who had nonischemic valvular cardiomyopathy, underwent valvular heart surgery (aortic valve replacement, mitral valve replacement, and/or mitral valve repair), and subsequently had an electrophysiology study (EPS), for a median of 2.8 years.

Sensing failure associated with the Medtronic Sprint Fidelis defibrillator lead.

Introduction: The diameter of implantable cardioverter-defibrillator (ICD) leads has become progressively smaller over time. However, the long-term performance characteristics of these smaller ICD leads are unknown.

Methods: We retrospectively evaluated 357 patients who underwent implantation of a Medtronic Sprint Fidelis defibrillating lead at two separate centers between September 2004 and October 2006.

Predictive value of microvolt T-wave alternans in patients with left ventricular dysfunction.

Objectives: The purpose of this study was to prospectively evaluate the utility of microvolt T-wave alternans (TWA) in predicting arrhythmia-free survival and total mortality in patients with left ventricular (LV) dysfunction.

Background: Microvolt TWA has been proposed as a useful tool in identifying patients unlikely to benefit from prophylaxis with implantable cardioverter-defibrillator (ICD) prophylaxis.

Methods: We evaluated 286 patients with an LV ejection fraction View Article and Find Full Text PDF

Effect of bundle branch block on microvolt T-wave alternans and electrophysiologic testing in patients with ischemic cardiomyopathy.

Background: T-wave alternans (TWA) and electrophysiology study (EPS) are used for risk stratification for sudden death.

Objective: The purpose of the study was to determine the effect of bundle branch block or intraventricular conduction delay on TWA and EPS.

Methods: 386 patients with coronary artery disease, nonsustained ventricular tachycardia, and left ventricular ejection fraction < or =40% underwent TWA and EPS, and were followed for 40 +/- 19 months.

Clinical and electrophysiological spectrum of idiopathic ventricular outflow tract arrhythmias.

Objectives: This study sought to compare and contrast the clinical and electrophysiological characteristics of outflow tract arrhythmias.

Background: Idiopathic ventricular outflow tract arrhythmias manifest clinically in 3 forms: 1) paroxysmal sustained monomorphic ventricular tachycardia (SMVT), 2) repetitive nonsustained ventricular tachycardia (NSVT), or 3) premature ventricular contractions (PVCs). Although these arrhythmias have a similar site of origin, it is unknown whether they share a common mechanism or similar clinical features.

Adenosine-insensitive focal atrial tachycardia: evidence for de novo micro-re-entry in the human atrium.

Objectives: The purpose of this work was to describe the entity and mechanism of adenosine-insensitive focal atrial tachycardia (AT).

Background: The majority of regular focal ATs demonstrate properties consistent with triggered activity, including termination by adenosine. Less commonly, AT may be due to enhanced automaticity, which is transiently suppressed by adenosine.

Effect of oral beta-blocker therapy on microvolt T-wave alternans and electrophysiology testing in patients with ischemic cardiomyopathy.

Background: Prior investigation has shown that intravenous beta-blockers decrease T-wave alternans (TWA) positivity in patients undergoing electrophysiology study (EPS). The present study examined whether oral beta-blocker use within 24 hours of TWA influences yield and predictive value of TWA and EPS.

Methods: We prospectively evaluated 387 patients (312 [81%] men, mean age 67 +/- 11 years) with coronary artery disease, left ventricular ejection fraction < or = 40%, and nonsustained ventricular tachycardia who underwent EPS and were followed for a mean of 2.

Newly detected atrial fibrillation following dual chamber pacemaker implantation.

Introduction: Pacemaker (PPM)-detected atrial high-rate episodes (AHREs) of even 5-minute duration may identify patients at increased risk for stroke and death. In this study, we sought to determine the incidence of newly detected atrial fibrillation (AF defined as an AHRE > or = 5 minutes) in patients following dual-chamber PPM implantation and to define the clinical predictors of developing AF.

Methods And Results: We evaluated 262 patients (142 male; age 74 +/- 12 years) without documented AF who underwent PPM implantation for sinus node dysfunction (n = 122) or atrioventricular block (n = 140).

Right and left ventricular outflow tract tachycardias: evidence for a common electrophysiologic mechanism.

Introduction: "Idiopathic" ventricular arrhythmias most often arise from the right ventricular outflow tract (RVOT), although arrhythmias from the left ventricular outflow tract (LVOT) are also observed. While previous work has elucidated the mechanism and electropharmacologic profile of RVOT arrhythmias, it is unclear whether those from the LVOT share these properties. The purpose of this study was to characterize the electropharmacologic properties of RVOT and LVOT arrhythmias.

Reversal of cardiomyopathy in patients with repetitive monomorphic ventricular ectopy originating from the right ventricular outflow tract.

Background: Tachycardia-induced cardiomyopathy caused by ventricular tachycardia is a well-defined clinical entity. Less well appreciated is whether simple ventricular ectopy can result in cardiomyopathy. We sought to examine a potential causal relationship between repetitive monomorphic ventricular ectopy originating from the right ventricular outflow tract and cardiomyopathy and the role of ablation in reversing this process.

Significance of adenosine-induced atrioventricular block in patients with unexplained syncope.

Objectives: The purpose of this study was to test whether a prolonged (>/=6 seconds) period of AV block in response to adenosine triphosphate (ATP) identifies additional patients at risk for bradycardia who may benefit from pacemaker implantation.

Background: Bradycardia is a common etiology for syncope in patients without underlying structural heart disease. Conventional testing using electrophysiologic and tilt table studies often fail to identify patients prone to episodes of symptomatic bradycardia.

Usefulness of prolonged QRS duration to identify high-risk ischemic cardiomyopathy patients with syncope and inducible ventricular tachycardia.

We evaluated 61 consecutive patients who had coronary artery disease, decreased left ventricular function, and syncope and underwent implantation of a cardioverter-defibrillator because sustained ventricular tachycardia was inducible at electrophysiologic testing. During a follow-up of 3.0 +/- 1.

Interactions of antiarrhythmic drugs and implantable devices in controlling ventricular tachycardia and fibrillation.

Implantable cardioverter defibrillators (ICDs) have proven highly successful in the treatment of life-threatening ventricular arrhythmias. Despite the efficacy of the ICD in terminating ventricular arrhythmias, antiarrhythmic drugs remain an important adjunct to ICD therapy. The use of antiarrhythmic drug therapy in combination with the ICD is synergistic in terms of beneficial effects, but also has the potential for some adverse interactions.