ORCID Profile
0000-0002-0189-171X
Current Organisations
University of Queensland
,
Prince Charles Hospital
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Wiley
Date: 13-10-2019
DOI: 10.1111/JCE.14217
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.HLC.2018.09.009
Abstract: Frequent ventricular ectopy is a common clinical presentation in patients suffering idiopathic ventricular outflow tract arrhythmias. These are focal arrhythmias that generally occur in patients without structural heart disease and share a predilection for characteristic anatomic sites of origin. Mechanistically, they are generally due to cyclic adenosine monophosphate (cAMP)-mediated triggered activity. As a result, there is typically an exercise or catecholamine related mode of induction and often a sensitivity to suppression with adenosine. Treatment options include clinical surveillance, medical therapy with anti-arrhythmic agents or catheter ablation. Medical therapy may offer symptomatic benefit but may have side-effects and usually results in burden reduction rather than eradication of ectopy. Catheter ablation using contemporary mapping techniques, whilst associated with some inherent procedural risk, is a potentially curative and safe option in most patients. Although usually associated with a good prognosis, some patients may develop an ectopy-mediated cardiomyopathy or, rarely, ectopy-induced polymorphic ventricular arrhythmias catheter ablation is the treatment of choice in those patients.
Publisher: Wiley
Date: 11-11-2018
DOI: 10.1111/PACE.13534
Publisher: Elsevier BV
Date: 11-2019
DOI: 10.1016/J.HLC.2018.09.014
Abstract: To describe the performance and clinical outcomes of consecutive patients having a leadless pacemaker (LP) implanted at a single institution. Clinical data and device parameters were prospectively collected on all patients undergoing LP implantation from November 2015 to April 2018. A total of 79 patients (52 male), median age of 78 years, was included. Leadless pacemaker implantation was successful in 76 patients (96%). Implantation failed in two patients due to excessive venous tortuosity and due to inadequate sensing in another. Seventy-three (73) patients (96%) had chronic atrial fibrillation and all had a Class I or II indication for pacing. Procedure time was 29minutes (IQR 21-43) and fluoroscopy time was 8minutes (IQR 5-13). The median R wave at implant was 11.2mV (IQR 6.9-15.0). The median capture threshold at 0.24ms was 0.5V (IQR 0.4-0.9) and impedance was 754Ω (IQR 680-880). Intraprocedural acute dislodgement occurred in one patient following cutting of the tether but successful snaring and reimplantation was performed. During a median follow-up of 355days (range 9-905), overall electrical performance has been excellent. No patients have been readmitted for device revision or complications. Five (5) patients (7%) died during follow-up from unrelated causes. Leadless pacemakers can be implanted safely and effectively in the majority of patients. Device electrical performance was excellent over a median follow-up of 12 months.
Publisher: Wiley
Date: 06-2017
DOI: 10.1111/PACE.13095
Abstract: 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.
Publisher: Elsevier BV
Date: 03-2019
DOI: 10.1016/J.HLC.2018.01.012
Abstract: Ectopy-mediated cardiomyopathy (EMC) is a potentially reversible form of left ventricular systolic dysfunction. Various risk factors for the development of EMC have been proposed in the literature. We aim to assess medium term outcomes of focal ventricular arrhythmia (VA) ablation in the setting of cardiomyopathy (CMP) and to validate published risk factors for EMC. Medium term recovery of left ventricular (LV) function and freedom from VA recurrence was assessed and compared between patients undergoing focal VA ablation in the setting of CMP and a control group with normal LV function. Univariate and multivariate analyses for CMP risk factors were performed and compared against prior published risk factors. Of 152 patients who underwent 170 focal VA ablation procedures, 54 (36%) had CMP and the remaining 98 patients had normal LV systolic function. At medium term follow-up, 85% of patients with CMP were free of VA recurrence and median left ventricular ejection fraction (LVEF) had improved from 40 to 52%. Age, male gender, premature ventricular complex (PVC) burden, non- right ventricular outflow tract (RVOT) sites of origin, PVC QRS duration and PVC minimum coupling interval were predictive of CMP on univariate analysis, but only gender persisted on multivariate analysis. Medium term outcome in patients undergoing focal VA in the setting of CMP are satisfactory with improvement in LV function achievable in most patients. Prior risk factors described in the literature are variable and inconsistent, likely reflecting heterogeneous study populations.
Publisher: Wiley
Date: 19-05-2021
DOI: 10.1002/JOA3.12554
Publisher: Wiley
Date: 28-05-2018
DOI: 10.1111/PACE.13363
Abstract: 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. A total of 152 patients underwent 170 consecutive procedures for ablation of focal VAs. MVP and cardiomyopathy were diagnosed by echocardiography. Outcomes following ablation were assessed in three groups: (1) LV papillary muscle VAs versus other sites, (2) LV papillary muscle VAs by the presence of MVP, and (3) LV papillary muscle VAs in the setting of cardiomyopathy. Nine of 23 (39%) patients undergoing ablation of LV papillary muscle VAs had MVP compared to none of 129 (0%) patients at other sites (P < 0.001). In the former group, acute procedural success was achieved in 60% and 80% of those with and without MVP, respectively (P = 0.28). Medium-term outcomes were comparable (P = 0.75). In patients with cardiomyopathy, the median LV ejection fraction improved from 40% to 54% following ablation (P = 0.007). Although MVP is strongly associated with LV papillary muscle VAs, MVP does not adversely affect the acute or medium-term outcomes of ablation. Systolic function can improve following ablation in patients with ectopy-mediated cardiomyopathy due to papillary muscle VAs.
Publisher: Wiley
Date: 21-07-2017
DOI: 10.1111/PACE.13141
Abstract: 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. Radiation dose measures were collected over a 2-year period in a single electrophysiology laboratory. Procedures were separated into seven groups: devices, biventricular devices, electrophysiology studies, standard radiofrequency ablation, complex atrial ablation, ablation for ventricular arrhythmias, and pulmonary vein isolation. In the first year, an older fluoroscopy system was used, and in the second year, a new system, with dose reduction strategies. Comparisons were also made to the literature with regard to radiation dose levels. Patient characteristics, fluoroscopy times, number of digital acquisitions, procedural times, and procedural success were largely similar between the old and new system across procedure groups. Overall dose area product (DAP) was reduced by 91% (5.0 [2.0-17.0] to 0.45 [0.16-2.61] Gycm An optimized contemporary digital fluoroscopy system, with low radiation dose configuration and continued good procedural practice, can result in ultra-low radiation levels for all electrophysiology procedures, without compromising procedural time or procedural success.
Publisher: Wiley
Date: 06-06-2021
DOI: 10.1111/JCE.15114
Abstract: Some patients have late recurrence after acutely successful radiofrequency catheter ablation (RFCA) of premature ventricular complexes (PVCs). The aim of this study was to evaluate predictors of long‐term success following acutely successful PVC RFCA. We identified consecutive patients at our institution with frequent PVCs undergoing RFCA and reviewed procedural data and medical records. Acute success was defined as elimination of targeted PVCs for at least 30‐min after RFCA. Long‐term success was defined as absence of targeted PVCs during all follow‐up visits and PVC‐burden % on follow‐up monitoring. Among 241 patients (mean age 57 ± 15 years, 58% male), 161 (66.8%) had long‐term success with median follow‐up of 17.7 (IQR, 12.2–29.8) months. Unadjusted predictors of late PVC recurrence were increasing age, diabetes mellitus and alcohol use, while female‐sex, shorter ablation‐time, right ventricular PVC‐origin, single PVC morphology, and earliest bipolar activation ≥24 ms pre‐QRS were predictors of long‐term success. In multivariate‐analysis, female‐sex, single‐PVC morphology and earliest‐onset of PVC ≥ 24 ms pre‐QRS were independent predictors for long‐term success. The positive‐predictive value of earliest‐bipolar onset of PVC ≥ 24 ms pre‐QRS for long‐term success was 0.77 ( p .001). Negative‐predictive value of PVC 15 ms pre‐QRS for long‐term success was 0.86 ( p = .003), suggesting that RFCA when the bipolar electrogram preceded QRS by ms was unlikely to result in long‐term success. Female‐sex, single‐PVC morphology, and earliest‐onset of bipolar electrogram ≥24 ms pre‐QRS were multivariable predictors of long‐term success in patients with PVCs undergoing RFCA. RFCA at sites with local onset ms pre‐QRS are unlikely to be successful.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2021
DOI: 10.1161/CIRCEP.120.009194
Abstract: In this review, we emphasize the unique value of recording the activation sequence of the His bundle or right bundle branch (RB) for diagnoses of various supraventricular and fascicular tachycardias. A close analysis of the His to RB (H-RB) activation sequence can help differentiate various forms of supraventricular tachycardias, namely atrioventricular nodal reentry tachycardia from concealed nodofascicular tachycardia, a common clinical dilemma. Furthermore, bundle branch reentry tachycardia and fascicular tachycardias often are included in the differential diagnosis of supraventricular tachycardia with aberrancy, and the use of this technique can help the operator make the distinction between supraventricular tachycardias and these other forms of ventricular tachycardias using the His-Purkinje system. We show that this technique is enhanced by the use of multipolar catheters placed to span the proximal His to RB position to record the activation sequence between proximal His potential to the distal RB potential. This allows the operator to fully analyze the activation sequence in sinus rhythm as compared to that during tachycardia and may help target ablation of these arrhythmias. We argue that 3 patterns of H-RB activation are commonly identified—the anterograde H-RB pattern, the retrograde H-RB (right bundle to His bundle) pattern, and the chevron H-RB pattern (simultaneous proximal His and proximal RB activation)—and specific arrhythmias tend to be associated with specific H-RB activation sequences. We show that being able to record and categorize this H-RB relationship can be instrumental to the operator, along with standard pacing maneuvers, to make an arrhythmia diagnosis in complex tachycardia circuits. We highlight the importance of H-RB activation patterns in these complex tachycardias by means of case illustrations from our groups as well as from prior reports.
No related grants have been discovered for Adam Lee.