Karen Halloran

Pulmonary Vein Antral Isolation for Paroxysmal Atrial Fibrillation: Results from Long-Term Follow-Up

Long‐Term Follow‐Up After Atrial Fibrillation Ablation. Introduction: Pulmonary veins play an important role in triggering atrial fibrillation (AF). Pulmonary vein isolation (PVI) is an effective treatment for patients with paroxysmal AF. However, the late AF recurrence rate in long‐term follow‐up of circumferential PV antral isolation (PVAI) is not well documented. We sought to determine the time to recurrence of arrhythmia after PVAI, and long‐term rates of sinus rhythm after circumferential PVAI.

Low risk of major complications associated with pulmonary vein antral isolation for atrial fibrillation: results of 500 consecutive ablation procedures in patients with low prevalence of structural heart disease from a single center.

Complications Associated With Pulmonary Vein Antral Isolation for Atrial Fibrillation. Objectives: To report the major complication rate associated with pulmonary vein antral isolation (PVAI) in a consecutive series of 500 patients from a single center.

Effect of respiration on catheter-tissue contact force during ablation of atrial arrhythmias

BACKGROUND Catheter-tissue contact is important for effective lesion creation. OBJECTIVE To assess the effect of respiration on contact force (CF) during atrial fibrillation and cavotricuspid isthmus (CTI)-dependent atrial flutter ablation. METHODS Patients undergoing CTI ablation alone (n = 15) and pulmonary vein (PV) isolation alone (n = 12) under general anesthesia were recruited. Lesions were delivered under ventilation (30 seconds) alternating with lesions delivered under apnea (30 seconds) at an adjacent anatomical site at CTI or PV antra. The average force (F(av)), force-time integral (FTI), and force variability were measured in a region-specific manner by using a novel CF-sensing ablation catheter. Operators were blinded to CF data. RESULTS F(av) and FTI were higher with apnea than with ventilation in all CTI and PV segments (P <.05), an effect attributed to drop in CF with each respiratory swing, resulting in greater force variability during ventilation (P <.05). Low FTI lesions (<500 g) were strongly associated with longer ablation time to achieve bidirectional CTI block (r(2) = .81; P <.001), left PVI (r(2) = .65; P = .009), and right PVI (r(2) = .41; P = .05). Sites with transient CTI block were associated with lower F(av) and FTI than were sites with persistent CTI block (P <.05). Sites of acute PV reconnection were associated with lower F(av) and FTI compared with non-reconnected sites (P <.001). CONCLUSIONS Catheter-tissue CF is critically influenced by respiration; greater CF is observed with ablation during apnea. Poor CF is implicated in longer ablation time to achieve CTI block or PV isolation and in acute reconnection.

Prospective Characterization of Catheter–Tissue Contact Force at Different Anatomic Sites During Antral Pulmonary Vein Isolation

Background— Catheter–tissue contact is critical for effective lesion creation. We characterized the contact force (CF) at different anatomic sites during antral pulmonary vein (PV) isolation for atrial fibrillation. Methods and Results— Two experienced operators performed PV isolation in 22 patients facilitated by a novel CF-sensing ablation catheter in a blinded fashion. Average CF and force-time integral data from 1602 lesions were analyzed. The left and right PV antra were divided into the following: carina, superior, inferior, anterior, and posterior quadrants for analysis. There was significant variability in CF within and between different PV quadrants (P<0.05). Lowest CF of all left PV sites was at the carina and anterior quadrant, whereas highest CF was at the superior and inferior quadrants (P<0.05). Lowest CF of all right PV sites was at the carina, whereas highest CF was at the anterior and inferior quadrants (P<0.05). When comparing similar PV quadrants on the left versus right (eg, left carina versus right carina), CF was always higher in the right PVs (P<0.05), except at the superior quadrant where CF was similar in the left and right PVs (P=0.19). There was no specific pattern of anatomic distribution of excess CF (P=0.39). Conclusions— Monitoring of catheter–tissue CF during PV isolation demonstrates significant variability in CF within and between different PV antral sites. Sites of lowest CF were the carina and anterior left PVs and the carina of the right PVs. This information may be important for improving ablation efficacy and clinical outcomes during PV isolation.

Catheter‐Tissue Contact Force Determines Atrial Electrogram Characteristics Before and Lesion Efficacy After Antral Pulmonary Vein Isolation in Humans

Electrogram (EGM) characteristics are used to infer catheter‐tissue contact. We examined if (a) atrial EGM characteristics predicted CF and (b) compared the value of CF versus other surrogates for predicting lesion efficacy.

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.

Ten-year trends in the use of catheter ablation for treatment of atrial fibrillation vs. the use of coronary intervention for the treatment of ischaemic heart disease in Australia.

AIMS Percutaneous coronary intervention (PCI) and catheter ablation are well-accepted therapeutic interventions for treatment of coronary artery disease and atrial fibrillation (AF), respectively. We sought to examine temporal trends in the provision of these services over the past decade in Australia. METHODS AND RESULTS A retrospective review of the numbers of PCIs and AF ablations from 2000/01 to 2009/10 was performed on data from three sources: the Australian Institute of Health, Welfare and Aging (AIHW), Medicare Australia database (MA), and local records at a high volume tertiary referral centre (RMH) for AF ablation. Linear regression models were fitted comparing trends in population-adjusted procedural numbers over the 10-year period. There was a 5% per year population-adjusted increment in PCIs over 10 years from both the AIHW and MA sources, respectively (P < 0.001). This was similar to the growth rate of all cardiovascular procedures (AIHW: 5.1 vs. 3.8%/year, P = 0.27). Atrial fibrillation ablations showed a 30.9, 23.2, and 39.8% per year population-adjusted increment over 10 years from the AIHW, MA, and RMH sources respectively (P < 0.001 for all). Growth of AF ablations was significantly higher than PCIs (P < 0.001 for AIHW and MA sources) and all cardiovascular procedures (AIHW: 30.9 vs. 3.8%/year, P < 0.001). CONCLUSION The provision of catheter-based AF ablation services in Australia has increased exponentially over the past decade. Its annual growth rate exceeded that of PCIs and all cardiovascular procedures. Given the increasing epidemic of AF, these data have critical implications for public health policy assessing the adequacy of infrastructure, training, and funding for AF ablation services.

Long-term Outcome Following Ablation of Atrial Flutter Occurring Late after Atrial Septal Defect Repair

Aims: In patients with surgical atrial septal defect (ASD) repair, late atrial flutters (AFLs), including cavotricuspid isthmus (CTI)‐dependent and non‐CTI‐dependent scar‐related flutter (AFL), are common. Radiofrequency ablation (RFA) of these arrhythmias has a high acute success rate. We aimed to characterize the long‐term freedom from atrial arrhythmias in this population.

Vagal Paroxysmal Atrial Fibrillation: Prevalence and Ablation Outcome in Patients Without Structural Heart Disease

Prevalence of Vagal Paroxysmal Atrial Fibrillation. Introduction: The prevalence of vagal and adrenergic atrial fibrillation (AF) and the success rate of pulmonary vein isolation (PVI) are not well defined. We investigated the prevalence of vagal and adrenergic AF and the ablation success rate of antral pulmonary vein isolation (APVI) in patients with these triggers compared with patients with random AF.

Esophageal hematoma after atrial fibrillation ablation: incidence, clinical features, and sequelae of esophageal injury of a different sort

Background— Esophageal hematoma recently has been reported as a form of esophageal injury after atrial fibrillation (AF) ablation, attributed to the use of transesophageal echocardiography (TEE). We sought to determine the incidence, clinical features, and sequelae of this form of esophageal injury. Methods and Results— This was a prospective series of 1110 AF ablation procedures performed under general anesthesia (GA) over 9 years. TEE was inserted after induction of GA to exclude left atrial appendage thrombus, define cardiac function, and guide transseptal puncture. The procedural incidence of esophageal hematoma was 0.27% (3/1110 procedures, mortality 0%). Odonyphagia, regurgitation, and hoarseness were the predominant symptoms, with an onset within 12 hours. There was absence of fever and neurological symptoms. Chest computed tomography excluded atrio-esophageal fistula and was diagnostic of esophageal hematoma localized to either the upper esophagus or extending the length of the mid and lower esophagus; endoscopy confirmed the diagnosis. Management was conservative in all cases comprising of ceasing oral intake and anticoagulation. Long term sequelae included esophageal stricture formation requiring dilatation, persistent esophageal dysmotility (mid esophageal hematoma), and vocal cord paralysis, resulting in hoarse voice (upper esophageal hematoma). Conclusions— Esophageal hematoma is a rare but important differential diagnosis for esophageal injury after TEE-guided AF ablation under GA, and can result in significant patient morbidity. Key clinical features differentiate presentation of esophageal hematoma from that of an atrio-esophageal fistula.Background— Esophageal hematoma recently has been reported as a form of esophageal injury after atrial fibrillation (AF) ablation, attributed to the use of transesophageal echocardiography (TEE). We sought to determine the incidence, clinical features, and sequelae of this form of esophageal injury. Methods and Results— This was a prospective series of 1110 AF ablation procedures performed under general anesthesia (GA) over 9 years. TEE was inserted after induction of GA to exclude left atrial appendage thrombus, define cardiac function, and guide transseptal puncture. The procedural incidence of esophageal hematoma was 0.27% (3/1110 procedures, mortality 0%). Odonyphagia, regurgitation, and hoarseness were the predominant symptoms, with an onset within 12 hours. There was absence of fever and neurological symptoms. Chest computed tomography excluded atrio-esophageal fistula and was diagnostic of esophageal hematoma localized to either the upper esophagus or extending the length of the mid and lower esophagus; endoscopy confirmed the diagnosis. Management was conservative in all cases comprising of ceasing oral intake and anticoagulation. Long term sequelae included esophageal stricture formation requiring dilatation, persistent esophageal dysmotility (mid esophageal hematoma), and vocal cord paralysis, resulting in hoarse voice (upper esophageal hematoma). Conclusions— Esophageal hematoma is a rare but important differential diagnosis for esophageal injury after TEE-guided AF ablation under GA, and can result in significant patient morbidity. Key clinical features differentiate presentation of esophageal hematoma from that of an atrio-esophageal fistula.