H. Haqqani

Catheter ablation of ventricular fibrillation: Importance of left ventricular outflow tract and papillary muscle triggers

BACKGROUND Monomorphic ventricular premature depolarizations (VPDs) have been found to initiate ventricular fibrillation (VF) or polymorphic ventricular tachycardia (PMVT) in patients with and without structural heart disease. OBJECTIVE The purpose of this study was to describe and characterize sites of origin of VPDs triggering VF and PMVT. METHODS The distribution of mapping-confirmed VPDs, electrophysiology laboratory findings, and results of radiofrequency catheter ablation were analyzed. RESULTS Among 1132 consecutive patients who underwent ablation for ventricular arrhythmias, 30 patients (2.7%) with documented VF/PMVT initiation were identified. In 21 patients, VF/PMVT occurred in the setting of cardiomyopathy; in 9 patients, VF/PMVT was idiopathic. The origin of VPD trigger was from the Purkinje network in 9, papillary muscles in 8, left ventricular outflow tract in 9, and other low-voltage areas unrelated to Purkinje activity in 4. Each distinct anatomic area of origin was associated with VF/PMVT triggers in patients with and without heart disease. Acute VPD elimination was achieved in 26 patients (87%), with a decrease in VPDs in another 3 patients (97%). During median follow-up of 418 days (interquartile range [IQR] 144-866), 5 patients developed a VF/PMVT recurrence after a median of 34 days (IQR 1-259). Rare recurrence was noted in patients with and without structural disease and from each distinct anatomic origin. The total burden of VF/PMVT episodes/shocks was reduced from a median of 9 (IQR 2.5-22.5) in the 3 months before ablation to 0 (IQR 0-0, total range 0-2) during follow-up (P <.0001). CONCLUSION Catheter ablation of VPD-triggered VF/PMVT is highly successful. Left ventricular outflow tract and papillary muscles are common and are previously unrecognized sites of origin of these triggers in patients with and without structural heart disease.

Predictive value of impedance changes for real-time contact force measurements during catheter ablation of atrial arrhythmias in humans

BACKGROUND Catheter-tissue contact force (CF) determines radiofrequency (RF) ablation lesion size. Impedance changes during RF delivery are used as surrogate markers for CF. The relationship between impedance and real-time CF in humans remains unknown. OBJECTIVES To determine whether impedance changes have predictive value for real-time CF during catheter ablation of atrial arrhythmias. METHODS Real-time CF, force-time integral, and impedance were measured in 2265 RF lesions for atrial fibrillation or flutter in 34 patients. Operators were blinded to CF measurements. Impedance preablation, at 5-second intervals for 30 seconds after the RF onset, maximal impedance fall and time to impedance plateau during RF were correlated with CF. Average CF was divided into low (≤20 g), intermediate (21-60 g), and high (>60 g) categories. RESULTS Preablation impedance poorly correlated with preablation CF (R = .07). Maximal impedance fall modestly correlated with average CF and force-time integral (R = .32 and .37, respectively). There was a large degree of overlap in impedance fall between different CF categories. A maximal impedance fall of 10 Ω could predict average CF of >20 g, with a sensitivity and specificity of 71% and 53% and a positive and negative predictive value of 51% and 49%, respectively. Impedance fall was only able to differentiate between different CF categories ≥15 seconds after the RF onset. Higher CFs moderately correlated with delayed plateau in impedance (R = .41). CONCLUSIONS Impedance measurements (both baseline and impedance fall) are, at best, moderately efficacious as surrogate markers for predicting real-time catheter-tissue CF. These findings highlight the importance of real-time CF measurements, rather than impedance changes to optimize ablation efficacy.

Non-Pharmacological Therapy for Atrial Fibrillation: Managing the Left Atrial Appendage

The prevalence of atrial fibrillation (AF) is increasing in parallel with an ageing population leading to increased morbidity and mortality. The most feared complication of AF is stroke, with the arrhythmia being responsible for up to 20% of all ischemic strokes. An important contributor to this increased risk of stroke is the left atrial appendage (LAA). A combination of the LAAs unique geometry and atrial fibrillation leads to low blood flow velocity and stasis, which are precursors to thrombus formation. It has been hypothesized for over half a century that excision of the LAA would lead to a reduction in the incidence of stroke. It has only been in the last 20–25 years that the knowledge and technology has been available to safely carry out such a procedure. We now have a number of viable techniques, both surgical and percutaneous, which will be covered in this paper.

Pericardiocentesis – How to do it

Pericardiocentesis is an important diagnostic and therapeutic technique, with the potential for significant morbidity and mortality if performed incorrectly. This article attempts to cover the anatomy, preparation, and techniques necessary to successfully perform pericardiocentesis.

Radiofrequency Catheter Ablation for Ventricular Tachycardia

The management of ventricular tachycardia (VT) has evolved considerably in recent times. The majority of patients with VT have structural heart disease and often implantable defibrillators. Implantable defibrillators can terminate ventricular arrhythmias and prevent sudden death but do not prevent these arrhythmias from occurring. Ventricular tachycardia may also occur in patients without structural heart disease and although these patients generally have a benign prognosis, the symptoms can be significant. Radiofrequency catheter ablation has a definite role as an alternative to anti-arrhythmic therapy in both groups of patients. This review outlines the indications, techniques and outcomes of catheter ablation in the management of patients with ventricular tachycardia.

National Heart Foundation of Australia and the Cardiac Society of Australia and New Zealand: Australian Clinical Guidelines for the Diagnosis and Management of Atrial Fibrillation 2018

1. Rationale for These Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1211 2. Key Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1212 3. Preamble . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1217 3.1. Epidemiology of Atrial Fibrillation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1217 3.2. The Process of Developing the 2018 Atrial Fibrillation Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1217

Improving the resolution of ventricular tachycardia substrate mapping: marrying (ultra)structure and function

Improving the Resolution of Ventricular Tachycardia Substrate Mapping: Marrying (Ultra)Structure and Function HARIS M. HAQQANI, M.B.B.S.(HONS), Ph.D., F.R.A.C.P.∗ and FRANCIS E. MARCHLINSKI, M.D., F.A.C.C., F.A.H.A., F.H.R.S.† From the ∗School of Medicine, The University of Queensland, Department of Cardiology, The Prince Charles Hospital, Brisbane, Australia and the † Section of Cardiac Electrophysiology, Cardiovascular Division, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA

Catheter ablation of papillary muscle arrhythmias: Implications of mitral valve prolapse and systolic dysfunction

The left ventricular (LV) papillary muscles are important components of the mitral valve apparatus. Catheter ablation of ventricular arrhythmias from these sites is challenging. We aim to describe the association between LV papillary muscle ventricular arrhythmias (VAs) and mitral valve prolapse (MVP), and to determine the outcomes of ablation in these patients with a focus on those with MVP and cardiomyopathy.

Epicardial Brugada syndrome ablation unmasking inferior J waves

Patients with Brugada syndrome are at risk of life‐threatening ventricular arrhythmias. Epicardial substrate ablation for Brugada syndrome has been described as a means of controlling these arrhythmias and recent reports describe elimination of the Brugada phenotype with ablation. We describe a unique case in which a patient developed inferior J waves with an early repolarization‐type electrocardiogram following successful epicardial infundibular substrate ablation (which eliminated the Brugada syndrome electrocardiogram on ajmaline challenge). We discuss the likely underlying pathophysiology responsible for this phenomenon, its relationship to the anatomic obstacles encountered during epicardial ablation, and the implications for long‐term arrhythmic risk.Patients with Brugada syndrome are at risk of life-threatening ventricular arrhythmias. Epicardial substrate ablation for Brugada syndrome has been described as a means of controlling these arrhythmias and recent reports describe elimination of the Brugada phenotype with ablation. We describe a unique case in which a patient developed inferior J waves with an early repolarization-type electrocardiogram following successful epicardial infundibular substrate ablation (which eliminated the Brugada syndrome electrocardiogram on ajmaline challenge). We discuss the likely underlying pathophysiology responsible for this phenomenon, its relationship to the anatomic obstacles encountered during epicardial ablation, and the implications for long-term arrhythmic risk.

Ultra-low radiation dose during electrophysiology procedures using optimized new generation fluoroscopy technology

Electrophysiology procedures require fluoroscopic guidance, with the associated potentially adverse effects of ionizing radiation. Newer fluoroscopy systems have more features that enable dose‐reduction strategies. This study aimed to investigate any reduction in radiation dose between an older fluoroscopy system (Philips Integris H5000, Philips Healthcare, Einhoven, Netherlands) and one of the latest systems (Siemens Artis Q, Siemens Healthcare, Erlangen, Germany), optimized with dose‐reduction strategies.