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In a male patient with D-transposition of the great arteries post Mustard repair, we report the inadvertent placement of an atrial pacemaker lead across the baffle into the pulmonary venous atrium managed with extraction and re-implantation.

Aims Cryoballoon pulmonary vein isolation (PVI) is a safe and effective treatment for atrial fibrillation (AF). Current limitations include incomplete vein occlusion due to balloon rigidity and inconsistent electrogram recording, which impairs identification of isolation. We aimed to evaluate the acute safety and performance of a novel cryoballoon system. Methods and results The system includes a steerable sheath, mapping catheter, and a balloon that maintains uniform inflation pressure and size following initiation of ablation. Protocol-directed cryoablation was delivered for 180 s for isolation documented in ≤60 s, otherwise freeze duration was 240 s. Primary endpoints were acute safety and vein isolation. Pulmonary vein isolation was confirmed at ≥30 min post-isolation. Data were compared across vein locations. Thirty patients with paroxysmal AF were enrolled at two centres and underwent PVI. Pulmonary vein isolation was achieved with cryoablation only in 100% of veins (120/120). Nadir temperature was −53.1 ± 5.3°C. The number of applications to achieve PVI was 1.4 ± 0.4 per vein. Of the 120 veins, 89 were isolated with a single cryothermal application (10/30 patients required only 4 total cryoablations). There were no procedural- or device-related serious adverse events at 30 days post-procedure. A subset (24/30) of patients was followed for 1-year and 71% (17/24) remained free of atrial arrhythmias. Six patients with arrhythmia recurrence were remapped and three had durable PVI for all four veins. Conclusion In this first human experience, the novel cryoballoon platform was safe, efficacious, and demonstrated a high proportion of successful single ablation isolation.

Permanent pacemakers are usually implanted using the venous tributaries of the arms. There are clinical situations where this approach may not be ideal or even possible. In these situations, techniques for permanent pacing via the tributaries of the legs can be used. We describe a method of pacing via a femoral venous approach using a subcutaneous pocket. This technique provides a safe alternative pacing site when avoiding the chest and neck regions.

BACKGROUND Catheter ablation has rapidly become an integral part of the management of many arrhythmias. AIMS To provide a history of clinical cardiac electrophysiology (EP) in New Zealand (NZ) and analysis of recent trends in EP procedures and catheter ablations across NZ, which has not previously been reported. METHODS EP case type and volume were obtained from the EP databases from each of the four public and four private EP centres in NZ from 1 January 2014 to 31 December 2018. Procedure rates were expressed as per million population. RESULTS A total of 7695 EP cases was performed, including 5929 (77%) in the public sector. Atrial fibrillation (AF) ablation was the most common procedure at 29%. EP procedure rates increased by 21% (to 353 per million in 2018), predominantly due to AF ablation rates increasing by 46%. Ventricular tachycardia ablation rates increased by 41% but only comprised 8% of procedures. There was a striking difference in the growth of EP procedure rates in the public compared to the private sector (4% vs 106%), as well as considerable differences in EP procedure and AF ablation rates across the public EP centres. NZ had lower ablation rates compared to countries with similar healthcare expenditure. CONCLUSION There has been a substantial increase in EP procedure and AF ablation rates in NZ and international trends suggest this growth will continue. However, there is considerable variation in procedure rates and growth trends between EP centres, highlighting inequities in access within the country.

Current generation left ventricular assist devices (LVADs) are powered by a percutaneous driveline. The high prevalence of driveline infections has motivated the development of transcutaneous energy transfer (TET) systems which eliminate driveline associated complications by wirelessly delivering power across the skin. Destination therapy (DT) requires long-term reliable operation of the TET electronics suggesting the use of hermetic packaging techniques as used in all other chronically implanted devices. TET coils dissipate heat during operation and in order for the technology to be suitable for patient use, sufficient power must be delivered while maintaining temperatures at levels deemed safe. The heating of a TET system designed for DT which uses hermetic packaging technology was evaluated in silico and in vivo. A numerical model was used to evaluate the temperature of the TET coils. The TET system was fabricated and assessed in vivo using an ovine model. The receiving coil was implanted subcutaneously in a sheep and the transmission coil placed in contact with the skin and concentric to the implanted coil. Temperatures of the system were measured using sensors fixed to the surface of the coils. Numerical modeling indicated that the maximum temperatures of the primary and secondary coil surfaces were 38.13°C and 38.41°C, respectively, when delivering 10 W continuously. Stable temperatures were observed in vivo after 70 minutes and the maximum skin and implant surface temperatures were 37.73°C and 38.31°C, respectively. This study showed that a hermetic, chronically implantable TET system is thermally safe when continuously delivering 10 W of power, sufficient to power modern LVADs.

Background Recently, a novel cryoballoon ablation catheter has demonstrated acute safety and efficacy in de novo pulmonary vein isolation (PVI) procedures in patients with paroxysmal atrial fibrillation (PAF). However, there are limited studies demonstrating the long-term efficacy. The aim of this study was to evaluate the long-term safety and efficacy of this novel cryoballoon in treating PAF. Methods This was a non-randomized, prospective, multicentre study enrolling 58 consecutive patients. Cryoablation was delivered for 180 s if time to isolation was ≤ 60 s. Otherwise a 240-s cryoablation was performed. One centre performed pre- and post-ablation high-density mapping (n = 9) to characterize lesion formation. After a 3-month blanking period, recurrence was defined as having any documented, symptomatic episode(s) of AF or atrial tachycardia. All patients were followed for 1 year. Results Acute PVI was achieved in 230 of 231 pulmonary veins (99.6%) with 5.3 ± 1.6 cryoablations per patient (1.3 ± 0.7 cryoablations per vein). Forty-three (77%) patients remained arrhythmia-free at 1-year follow-up. Four patients (6.9%) experienced phrenic nerve injury (3 resolved during the index procedure; 1 resolved at 6 months). One serious adverse device event was reported: femoral arterial embolism event occurring 2 weeks post-index procedure. For patients who underwent high-density mapping, cryoablation was antral with 50% of the posterior wall ablated. Conclusions Initial multicentre clinical experience with a novel cryoballoon has demonstrated safety and efficacy of PVI in patients with PAF. Ablation with this cryoballoon provides a wide, antral lesion set with significant debulking of the posterior wall of the left atrium.

Carotid bodies (CBs) are peripheral chemoreceptors, which are primary sensors of systemic hypoxia and their activation produces respiratory, autonomic, and cardiovascular adjustments critical for body homeostasis. We have previously shown that carotid chemoreceptor stimulation increases directly recorded cardiac sympathetic nerve activity (cardiac SNA) which increases coronary blood flow (CoBF) in conscious normal sheep. Previous studies have shown that chemoreflex sensitivity is augmented in heart failure (HF). We hypothesized that carotid chemoreceptor stimulation would increase CoBF to a greater extent in HF than control sheep. Experiments were conducted in conscious HF sheep and control sheep (n = 6/group) implanted with electrodes to record diaphragmatic electromyography (dEMG), flow probes to record CoBF as well as arterial pressure. There was a significant increase in mean arterial pressure (MAP), CoBF and coronary vascular conductance (CVC) in response to potassium cyanide (KCN) in both groups of sheep. To eliminate the effects of metabolic vasodilation, the KCN was repeated while the heart was paced at a constant level. In this paradigm, the increase in CoBF and CVC was augmented in the HF group compared to the control group. Pre-treatment with propranolol did not alter the CoBF or the CVC increase in the HF group indicating this was not mediated by an increase in cardiac sympathetic drive. The pressor response to CB activation was abolished by pre-treatment with intravenous atropine in both groups, but there was no change in the CoBF and vascular conductance responses. Our data suggest that in an ovine model of HF, carotid body (CB) mediated increases in CoBF and CVC are augmented compared to control animals. This increase in CoBF is mediated by an increase in cardiac SNA in the control group but not the HF group.

Background Dispersion and gradients in repolarization have been associated with life‐threatening arrhythmias, but are difficult to quantify precisely from surface electrocardiography. The objective of this study was to evaluate electrocardiographic imaging (ECGI) to noninvasively detect repolarization‐based abnormalities. Methods and Results Ex vivo data were obtained from Langendorff‐perfused pig hearts (n=8) and a human donor heart. Unipolar electrograms were recorded simultaneously during sinus rhythm from an epicardial sock and the torso‐shaped tank within which the heart was suspended. Regional repolarization heterogeneities were introduced through perfusion of dofetilide and pinacidil into separate perfusion beds. In vivo data included torso and epicardial potentials recorded simultaneously in anesthetized, closed‐chest pigs (n=5), during sinus rhythm, and ventricular pacing. For both data sets, ECGI accurately reconstructed T‐wave electrogram morphologies when compared with those recorded by the sock (ex vivo: correlation coefficient, 0.85 [0.52–0.96], in vivo: correlation coefficient, 0.86 [0.52–0.96]) and repolarization time maps (ex‐vivo: correlation coefficient, 0.73 [0.63–0.83], in vivo: correlation coefficient, 0.76 [0.67–0.82]). ECGI‐reconstructed repolarization time distributions were strongly correlated to those measured by the sock (both data sets, R 2 ≥0.92). Although the position of the gradient was slightly shifted by 8.3 (0–13.9) mm, the mean, max, and SD between ECGI and recorded gradient values were highly correlated ( R 2 =0.87, 0.75, and 0.86 respectively). There was no significant difference in ECGI accuracy between ex vivo and in vivo data. Conclusions ECGI reliably and accurately maps potentially critical repolarization abnormalities. This noninvasive approach allows imaging and quantifying individual parameters of abnormal repolarization‐based substrates in patients with arrhythmogenesis, to improve diagnosis and risk stratification.

Background Recently, a novel cryoballoon (CB; POLARx) has been developed with increased steerability which maintains size and pressure throughout the ablation. Initial clinical data has demonstrated acute procedural safety and efficacy in de novo pulmonary vein isolation (PVI) procedures in patients with paroxysmal atrial fibrillation (AF). However, there are limited studies demonstrating the long-term efficacy of the CB. Purpose To evaluate the long-term safety and efficacy of the novel CB in treating paroxysmal AF. Methods This was a non-randomized, prospective, multi-center study. Fifty-eight consecutive patients with paroxysmal AF were enrolled at 4 centers for de novo PVI procedures. Cryoablation was delivered for 180s if time to isolation was ≤60s. Otherwise a 240s cryoablation was performed. PVI was confirmed with entrance and exit block testing. Patients were followed for 1 year with 24-hour Holter monitoring at 3, 6, and 12 months. After a 3-month blanking period, recurrence was defined as having any documented, symptomatic episode(s) of AF or atrial tachycardia. Results Acute isolation with the CB was achieved in 230 of 231 pulmonary veins (99.6%) with 5.2±1.5 cryoapplications per patient (1.3±0.6 cryoapplications per vein). There were 4 patients (6.9%) with phrenic nerve injury (3 resolved during the index procedure; 1 resolved at 6 months follow-up). One serious adverse device event was reported: femoral arterial embolism event occurring 2 weeks post index procedure (1.7%). Of the 56 patients that had complete 12-month follow-up, 43 (76.8%) were free from recurrent atrial arrhythmias. Conclusion Initial multicenter clinical experience with the novel CB has demonstrated long-term safety and efficacy of PVI in patients with paroxysmal AF. Further studies are underway to confirm these findings. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): Boston Scientific

Activation of the carotid body (CB) using intracarotid potassium cyanide (KCN) injection increases coronary blood flow (CoBF). This increase in CoBF is considered to be mediated by co-activation of both the sympathetic and parasympathetic nerves to the heart. However, whether cardiac sympathetic nerve activity (cardiac SNA) actually increases during CB activation has not been determined previously. We hypothesized that activation of the CB would increase directly recorded cardiac SNA, which would cause coronary vasodilatation. Experiments were conducted in conscious sheep implanted with electrodes to record cardiac SNA and diaphragmatic electromyography (dEMG), flow probes to record CoBF and cardiac output, and a catheter to record arterial pressure. Intracarotid KCN injection was used to activate the CB. To eliminate the contribution of metabolic demand on coronary flow, the heart was paced at a constant rate during CB chemoreflex stimulation. Intracarotid KCN injection resulted in a significant increase in directly recorded cardiac SNA frequency (from 24 ± 2 to 40 ± 4 bursts/min; P < 0.05) as well as a dose-dependent increase in mean arterial pressure (79 ± 15 to 88 ± 14 mmHg; P < 0.01) and CoBF (75 ± 37 vs. 86 ± 42 mL/min; P < 0.05). The increase in CoBF and coronary vascular conductance to intracarotid KCN injection was abolished after propranolol infusion, suggesting that the increased cardiac SNA mediates coronary vasodilatation. The pressor response to activation of the CB was abolished by pretreatment with intravenous atropine, but there was no change in the coronary flow response. Our results indicate that CB activation increases directly recorded cardiac SNA, which mediates vasodilatation of the coronary vasculature.

Introduction: Low nadir temperature (N T ) and long thaw times with cryoballoon ablation are associated with successful PVI. Recently, a cryo-system was designed to improve catheter stability during ablation via a balloon (CB, POLARx™, Boston Scientific) that maintains uniform pressure and size. The purpose of this study was to evaluate whether the CB biophysical parameters, including time to -40 o C (TT40), N T , time to thaw (iTT0), and time to 15 o C (iTT15), are associated with acute PVI success in paroxysmal AF patients. Methods: Ablation was delivered for 180s if isolation was achieved in ≤ 60s or 240s if isolation occurred after 60s. PVI was confirmed via entrance and exit block. Biophysical parameters were evaluated for 3 groups: block with 180s ablation, block with 240s ablation, and for unsuccessful initial treatments (gap veins). The diagnostic accuracy for predicting PVI was assessed using area under (AUC) the receiver operator characteristic (ROC) curve for ablations > 120s. Results: Forty-six consecutive de novo PVI procedures at 4 centers were analyzed (n=234 ablations). All PVs were isolated using the CB alone, with the vast majority within 60s. During freeze, TT40 and N T were significantly shorter and colder for isolated veins compared to gap veins (Table). During thaw, iTT0 and iTT15 were significantly longer for isolated veins compared to gap veins (Table). ROC analysis found iTT15 had the highest diagnostic accuracy for isolation (AUC: 0.85) followed by N T (AUC: 0.81), iTT0 (AUC: 0.77), and TT40 (AUC: 0.72). Optimal cutoff values for iTT15 and N T were 33.5s and -48 o C, which had positive predictive values for acute block of 96.6% and 93.5%. Conclusions: When using the novel CB, ablations reaching < -48 o C and having thaw times to 15 o C > 33.5s were predictive of acute block in PVI, providing guidance toward improved workflow and potential reduction in procedural time.

Background Pulmonary vein isolation using cryotherapy is an established treatment for the management of patients with paroxysmal atrial fibrillation. Ablation using the commercially available balloon cryocatheter has been shown to create wide antral pulmonary vein isolation. A novel balloon cryocatheter (BCC) has been designed to maintain uniform pressure and size during ablation, potentially improving contact with the antral anatomy. The extent of ablation created using the novel BCC has not previously been established. Purpose To determine the anatomical extent of pulmonary vein isolation using electroanatomical mapping when performing catheter ablation for paroxysmal atrial fibrillation using the novel BCC. Methods Nine consecutive patients underwent pre-procedure computed tomography angiography of the left atrium to quantify the chamber dimensions. An electroanatomical map was created using the cryoablation system mapping catheter and a high definition mapping system. A bipolar voltage map was obtained following ablation to determine the extent of pulmonary vein isolation ablation. A volumetric technique was used to quantify the extent of vein and posterior wall electrical isolation in addition to traditional techniques for proving entrance and exit block. Results All patients had paroxysmal atrial fibrillation, mean age 56 years, 7 (78%) male. Electrical isolation was achieved for 100% of the pulmonary veins; mean total procedure time was 109 min (+/- 26 SD), and fluoroscopy time 14.9 min (+/- 2.4 SD). The median treatment applications per vein was one (range one - four), and median treatment duration 180 sec (range 180 -240). Left atrial volume 32 mL/m2 (+/- 7 SD), and mean left atrial posterior wall area 22 cm2 (+/- 4 SD). Data was available for quantitative assessment of the extent of ablation for eight patients. No lesions (0 of 32) were ostial in nature. The antral surface area of ablation was not statistically different between the left and right sided pulmonary veins (p 0.63), which were 5.9 (1.6 SD) and 5.4 (2.1 SD) cm2 respectively. In total 50% of the posterior left atrial wall was ablated. Conclusion Pulmonary vein isolation using a novel BCC provides a wide and antral lesion set. There is significant debulking of the posterior wall of the left atrium. Abstract Figure.

This report describes the occurrence of desynchronization in a patient with a cardiac resynchronization device programmed with an active pacemaker-mediated tachycardia algorithm based on AV delay modification. Desynchronization was precipitated by sinus tachycardia and the abrupt return of the prevailing AV delay that followed the periodic prolongation of the AV delay mandated by activity of the algorithm. Prevention of desynchronization in this setting requires programming a right ventricular upper rate interval longer than the sum of the programmed ventriculoatrial interval and the AV delay.

Background The New Zealand Cardiac Implanted Device Registry (Device) has recently been developed under the auspices of the New Zealand Branch of the Cardiac Society of Australia and New Zealand. This study describes the initial Device registry cohort of patients receiving a new pacemaker, their indications for pacing and their perioperative complications. Methods The Device Registry was used to audit patients receiving a first pacemaker between 1 st January 2014 and 1 st June 2015. Results We examined 1611 patients undergoing first pacemaker implantation. Patients were predominantly male (59%), and had a median age of 70 years. The most common symptom for pacemaker implantation was syncope (39%), followed by dizziness (30%) and dyspnoea (12%). The most common aetiology for a pacemaker was a conduction tissue disorder (35%), followed by sinus node dysfunction (22%). Atrioventricular (AV) block was the most common ECG abnormality, present in 44%. Dual chamber pacemakers were most common (62%), followed by single chamber ventricular pacemakers (34%), and cardiac resynchronisation therapy – pacemakers (CRT-P) (2%). Complications within 24hours of the implant procedure were reported in 64 patients (3.9%), none of which were fatal. The most common complication was the need for reoperation to manipulate a lead, occurring in 23 patients (1.4%). Conclusion This is the first description of data entered into the Device registry. Patients receiving a pacemaker were younger than in European registries, and there was a low use of CRT-P devices compared to international rates. Complications rates were low and compare favourably to available international data.

Background: The Heart Team approach has become an integral part of modern cardiovascular medicine. To evaluate current opinions and real-world practice among lead extraction practitioners, an online survey was created and distributed among a pool of lead extraction specialists participating in the International Lead Extraction Expert Meeting (ILEEM) 2018. Methods: The online survey consisted of 10 questions and was performed using an online survey tool (www.surveymonkey.com). The collector link was sent to 48 lead extraction experts via email. Results: A total of 43 answers were collected (89% return rate) from lead extraction experts in 16 different countries. A great majority (83.7%) of the respondents performed more than 30 lead extraction procedures per year. The most common procedural environment in this survey was the hybrid operating room (67.4%). Most procedures were performed by electrophysiologists and cardiologists (80.9%). Important additional members of the current lead extraction teams were cardiac surgeons (79.1%), anesthesiologists (95.3%) and operating room scrub nurses (76.7%). An extended Heart Team is regarded beneficial for patient care by 86.0%, with potential further members being infectious diseases specialists, intensivists and radiologists. Team training activities are performed in 48.8% of participating centers. Conclusions: This survey supports the importance of establishing lead extraction Heart Teams in specialized lead extraction centers to potentially improve patient outcomes. The concept of a core and an extended heart team approach in lead extraction procedures is introduced.

Testing new therapies in heart failure (HF) requires a chronic stable model of HF in large animals. Microembolization of the coronary arteries has been used to model HF previously; however, neural control has not been previously explored in this model. Thus the aim of this study was to further characterize neural control in this model of HF. HF was induced by infusion of microspheres (45 micron; 1.3 ml) into the proximal left coronary artery or left descending coronary arteries, with three sequential embolizations over 3 weeks. Twelve to 14 weeks after the final embolization, and when ejection fraction had decreased below 45%, animals were instrumented to record blood pressure and heart rate. Baroreflex control of heart rate was investigated in conscious animals. Additionally, pressure-volume loops were constructed under anesthesia. Embolization-induced HF was associated with a decrease in mean arterial pressure (67 ± 2 vs. 85 ± 4 mmHg, p < 0.05), an increase in heart rate (108 ± 4 vs. 94 ± 4 bpm, p < 0.05), and a significant increase in left ventricular end-diastolic pressure (11.4 ± 2 vs. 6.2 ± 1 mmHg, p < 0.01). Under conscious conditions, there was a significant decrease in the gain (−8.2 ± 2 vs. −4.1 ± 1 beats/min/mmHg, p < 0.05) as well as the lower plateau of the baroreflex in HF compared to control animals. HF was also associated with significantly increased respiratory rate (107 ± 4 vs. 87 ± 4 breaths/min, p < 0.01) and incidence of apneas (520 ± 24 vs. 191 ± 8 apnea periods >4 s, p < 0.05), compared to control sheep. The microembolization model of heart failure is associated with an increase in left ventricular end-diastolic pressure, impaired cardiac function, and altered baroreflex control of the heart. These findings suggest this chronic model of HF is appropriate to use for investigating interventions aimed at improving neural control in HF.

Altered electrical behavior alongside healed myocardial infarcts (MIs) is associated with increased risk of sudden cardiac death. However, the multidimensional mechanisms are poorly understood and described. This study characterizes, for the first time, the intramural spread of electrical activation in the peri-infarct region of chronic reperfusion MIs. Four sheep were studied 13 wk after antero-apical reperfusion infarction. Extracellular potentials (ECPs) were recorded in a ~20 × 20-mm2 region adjacent to the infarct boundary (25 plunge needles NEW & NOTEWORTHY Intramural in vivo measurements of peri-infarct electrical activity were not available before this study. We use pace-mapping in a three-dimensional electrode array to show that a subset of stimuli in the peri-infarct region initiates coordinated myocardial activation some distance from the stimulus site with substantial associated time delays. This is site dependent and heterogeneous and occurs for

The ANZACS-QI Cardiac Implanted Device Registry (ANZACS-QI DEVICE) collects data on cardiac implantable electronic devices inserted in New Zealand. We evaluated completeness of data capture and quality of ANZACS-QI DEVICE in 2016.Complete datasets within ANZACS-QI DEVICE, comprising DEVICE-PPM (permanent pacemakers) and DEVICE-ICD (implantable cardioverter defibrillators), from 1 January 2016 to 31 December 2016 were linked with the National Hospitalisation dataset (all New Zealand public hospital admissions). The total number of implants included procedures captured in either dataset. Variables assessed included age, gender, ethnicity, procedure type, implanting centre, admission and procedure date.DEVICE-PPM captured 85.9% of all PPM procedures (n=2,512). This was similar regardless of age, sex and ethnicity. In the 84.4% of procedures captured in both datasets, agreement was97% for all variables except admission date (90.1%). DEVICE-ICD captured 81.3% of all ICD procedures (n=690). Capture was similar across age, sex and ethnicity groups. In the 76.8% of procedures captured in both datasets, agreement was96% for all variables except admission date (90.6%).The ANZACS-QI DEVICE registry had a good capture rate and excellent agreement with the national dataset. This high concordance supports the use of both datasets for future research.

ObjectiveData describing outcomes after implantable cardioverter-defibrillator (ICD) unit generator replacement in patients with heart failure (HF) with primary prevention devices are limited.MethodData on patients with HF who underwent primary prevention ICD/cardiac resynchronisation therapy-defibrillator (CRT-D) implantation from 2007 until mid-2015 who subsequently received unit generator replacement were analysed. Outcomes assessed were mortality, appropriate ICD therapy and shock, and procedural complications.Results61 of 385 patients with HF with primary prevention ICD/CRT-D undergoing unit generator replacement were identified. Follow-up period was 1.8±1.5 years after replacement. 43 (70.5%) patients had not received prior appropriate ICD therapy prior to unit replacement. The cumulative risks of appropriate ICD therapy at 1, 3 and 5 years after unit replacement in those without prior ICD therapy were 0%, 6.2% and 50% compared with 6.2%, 59.8% and 86.6%, respectively (p=0.005) in those with prior ICD therapies. No predictive factors associated with appropriate ICD therapy after replacement could be identified. 41 (32.8%) patients no longer met guideline indications at the time of unit replacement but risks of subsequent appropriate ICD interventions were not different compared with those who continued to meet primary prevention ICD indications.The 5-year mortality risk after unit replacement was 18.4% and there were high procedural complication rates (9.8%).ConclusionNo predictive marker successfully stratified patients no longer needing ICD support prospectively. Finding such a marker is important in decision-making about device replacement particularly given the concerns about the complication rates. These factors should be considered at the time of ICD unit replacement.

This first-in-human study evaluated the safety and technical feasibility of the Tempo temporary cardiac pacing lead (BioTrace Medical), which includes a novel fixation mechanism and soft tip.Complications of temporary pacing leads include dislodgment, arrhythmias, and ventricular perforation. Temporary pacing applications have increased with transcatheter aortic valve replacement (TAVR) growth, for rapid pacing during balloon valvuloplasty (BAV) and valve deployment, and for periprocedural bradyarrhythmia support.Eligible patients required temporary pacing for TAVR, BAV, or electrophysiology (EP) procedures. Transthoracic echocardiograms were obtained at baseline and 24 hours after lead removal. Safety was defined as freedom from pericardial effusion requiring intervention or evidence of tamponade. Technical feasibility involved successful intracardiac delivery and pace capture. Additional evaluations included pacing threshold (PCT), rapid pacing, dislodgment, or sustained ventricular arrhythmias. Follow-up was to 30 days.Twenty-five patients (60% female; mean age, 64 ± 19 years) underwent 13 TAVRs (7 Sapien 3 valves [Edwards Lifesciences], 4 CoreValves [Medtronic], and 2 Lotus valves [Boston Scientific]), 11 EP procedures, and 1 BAV at two New Zealand centers from January 2016 to June 2016. Safety was met in all patients, with no device-related adverse events. Technical feasibility was achieved in 23 cases (92%); 2 patients had unsuitable anatomy. No patient had lead dislodgment or sustained ventricular arrhythmias, and the final procedural PCT was 0.7 ± 0.5 mA. Rapid pacing was successful in all cases. Five patients had successful postprocedural use up to 5 days.This first-in-human study demonstrates the safety and technical feasibility of the Tempo lead, providing stable periprocedural temporary pacing support.

The number of cardiac implantable electronic device (CIED) implantations has increased over recent years. Transvenous lead extraction (TLE), as a part of an overall lead management strategy, has also been increasing, not only as a consequence of this growth, but also because of increasing rates of infection, lead failure, awareness of indications for lead management, and development of extraction tools. Clinical research is essential for understanding efficacy and risks of TLE.

Background: Inverse electrocardiographic mapping reconstructs cardiac electrical activity from recorded body surface potentials. This noninvasive technique has been used to identify potential ablation targets. Despite this, there has been little systematic evaluation of its reliability. Methods: Torso and ventricular epicardial potentials were recorded simultaneously in anesthetized, closed-chest pigs (n=5), during sinus rhythm, epicardial, and endocardial ventricular pacing (70 records in total). Body surface and cardiac electrode positions were determined and registered using magnetic resonance imaging. Epicardial potentials were reconstructed during ventricular activation using experiment-specific magnetic resonance imaging–based thorax models, with homogeneous or inhomogeneous (lungs, skeletal muscle, fat) electrical properties. Coupled finite/boundary element methods and a meshless approach based on the method of fundamental solutions were compared. Inverse mapping underestimated epicardial potentials >2-fold ( P RESULTS: Mean correlation coefficients for reconstructed epicardial potential distributions ranged from 0.60±0.08 to 0.64±0.07 across all methods. Epicardial electrograms were recovered with reasonable fidelity at ≈50% of sites (median correlation coefficient, 0.69–0.72), but variation was substantial. General activation spread was reproduced (median correlation coefficient, 0.72–0.78 for activation time maps after spatio-temporal smoothing). Epicardial foci were identified with a median location error ≈16 mm (interquartile range, 9–29 mm). Inverse mapping with meshless method of fundamental solutions was better than with finite/boundary element methods, and the latter were not improved by inclusion of inhomogeneous torso electrical properties. Conclusions: Inverse potential mapping provides useful information on the origin and spread of epicardial activation. However the spatio-temporal variability of recovered electrograms limit resolution and must constrain the accuracy with which arrhythmia circuits can be identified independently using this approach.

Background— The relationship between epicardial and body surface potentials defines the forward problem of electrocardiography. A robust formulation of the forward problem is instrumental to solving the inverse problem, in which epicardial potentials are computed from known body surface potentials. Here, the accuracy of different forward models has been evaluated experimentally. Methods and Results— Body surface and epicardial potentials were recorded simultaneously in anesthetized closed-chest pigs (n=5) during sinus rhythm, and epicardial and endocardial ventricular pacing (65 records in total). Body surface potentials were simulated from epicardial recordings using experiment-specific volume conductor models constructed from magnetic resonance imaging. Results for homogeneous (isotropic electric properties) and inhomogeneous (incorporating lungs, anisotropic skeletal muscle, and subcutaneous fat) forward models were compared with measured body surface potentials. Correlation coefficients were 0.85±0.08 across all animals and activation sequences with no significant difference between homogeneous and inhomogeneous solutions ( P =0.85). Despite this, there was considerable variance between simulated and measured body surface potential distributions. Differences between the body surface potential extrema predicted with homogeneous forward models were 55% to 78% greater than observed ( P P Conclusions— These results demonstrate that homogeneous volume conductor models introduce substantial spatial inaccuracies in forward problem solutions. This probably affects the precision of inverse reconstructions of cardiac potentials, in which this assumption is made.

Aims Pulmonary vein isolation (PVI) is the cornerstone of catheter ablation of atrial fibrillation (AF). The intervenous ridge (IVR) may be incorporated into ablation strategies to achieve PVI; however, randomized trials are lacking. We performed a randomized multi-centre international study to compare the outcomes of (i) circumferential antral PVI (CPVI) alone ( minimal ) vs. (ii) CPVI with IVR ablation to achieve individual PVI ( maximal ). Methods and results Two hundred and thirty-four patients with paroxysmal AF underwent CPVI and were randomized to a minimal or maximal ablation strategy. The primary outcome of recurrent atrial arrhythmia was assessed with 7-day Holter monitoring at 6 and 12 months. PVI was achieved in all patients. Radiofrequency ablation time was longer in the maximal group (46.6 ± 14.6 vs. 41.5 ± 13.1 min; P < 0.01), with no significant differences in procedural or fluoroscopy times. At mean follow-up of 17 ± 8 months, there was no difference in freedom from AF after a single procedure between a minimal (70%) and maximal ablation strategy (62%; P = 0.25). In the minimal group, ablation was required on the IVR to achieve electrical isolation in 44%, and was associated with a significant reduction in freedom from AF (57%) compared with the minimal group without IVR ablation (80%; P < 0.01). Conclusion There was no statistically significant difference in freedom from AF between a minimal and maximal ablation strategy. Despite attempts to achieve PVI with antral ablation, IVR ablation is commonly required. Patients in whom antral isolation can be achieved without IVR ablation have higher long-term freedom from AF (the Minimax study; ACTRN12610000863033).

Background Implantable cardioverter‐defibrillator (ICD) therapy is indicated for selected heart failure patients for the primary prevention of sudden cardiac death. Little is known about the outcomes in patients selected for primary prevention device therapy in the northern region of New Zealand. Method Heart failure patients with systolic dysfunction who underwent primary prevention ICD/cardiac resynchronization therapy‐defibrillator (CRT‐D) implantation between January 1, 2007, and June 1, 2015, were included. Complications, mortality, and hospitalization events were reviewed. Results Three hundred and eighty‐five primary prevention devices were implanted (269 ICD, 116 CRT‐D). Mean age at implant was 59.1 ± 11.4 years. Mean duration of follow‐up was 3.64 ± 2.17 years. The commonest cause of death was heart failure (41.8%). Only 2 patients died from sudden arrhythmic death. The 5‐year heart failure mortality rate was 6%, whereas the 5‐year sudden arrhythmic death rate was 0.3%. Heart failure hospitalizations were commoner in those who received ICD than CRT‐D (67.7% vs 25.8%, P < .001). Maori patients have low implant rates (14%) with relatively high rates of admissions with heart failure and ventricular arrhythmia admissions, Conclusions Even in appropriately selected heart failure patients who received primary prevention devices, only a small percentage died as a result of sudden arrhythmic death. CRT‐D should be the device of choice where appropriate in heart failure patients. Significant challenges remain to improve access to device therapy and maximize benefit to those who do get implanted.

Heart failure (HF) is a common health problem and has reached epidemic in many western countries. Despite the current era of HF treatment, the risk of sudden cardiac death (SCD) in HF remains significant. Implantable cardioverter defibrillator (ICD) support has been shown to reduce the risk of SCD in patients with HF and impaired left ventricular function. Prophylactic ICD implantation in HF patients seems a logical step to reduce mortality through a reduction in SCD. However, ICD implantation is an invasive procedure, and both short- and long-term complications can occur. This needs to be carefully considered when evaluating the risk-benefit ratio of ICD implantation for individual patients. As the severity of HF increases, the proportion of SCD compared with HF-related deaths decreases. The challenge lies in identifying patients with HF who are at significant risk of SCD and who would most benefit from an ICD in addition to other anti-arrhythmic strategies. This review offers insight on the applicability and practicability of ICD for this growing population.

Background Cardiac implantable electronic devices (CIEDs) have now become common therapeutic adjuncts for patients prior to orthotopic heart transplantation (OHT). Removal of the generator and the intracardiac components occurs at time of transplantation but removal of the intravascular portion of leads may be unsuccessful without specialized extraction equipment. Methods We performed a retrospective audit of chest radiographs and clinical records of patients undergoing OHT at Green Lane and Auckland City Hospitals between 2002 and 2012. Results At the time of transplant surgery, 56 of 100 patients had a CIED in situ. Hardware was retained postoperatively in 22 (39%), and the CIED had been in situ for 47 (interquartile range [IQR] 16–68) months for these cases, compared to 14 (IQR 3–24) months in those without. In two (9%) patients, the device generator was electively explanted during the week following OHT. There were no subsequent procedures undertaken to remove retained lead fragments. One (4%) had lead fragment embolization, one (4%) had endoluminal fragment migration, and one (4%) had lead fragment erosion into the mediastinum; all were asymptomatic and without adverse clinical sequelae. There was no infection associated with this hardware. The presence of retained lead fragments was not associated with additional mortality. Conclusions Retained lead fragments following OHT occur commonly, without adverse clinical events for this cohort; however, the long-term clinical implications remain uncertain. Complete removal of all CIED hardware should be attempted at the time of OHT, and when this is not possible leads should be left in a state that facilitates their removal at a later date if required.

ObjectiveCardiac resynchronisation therapy (CRT) devices have been shown to improve heart failure (HF) symptoms, survival and improve quality of life (QoL). We evaluated the overall impact of CRT on recurrent hospitalisations and survival in real-world patients with HF.DesignRetrospective observational study.SettingNorthern region of New Zealand.ParticipantsPatients with HF who underwent CRT device implantation in between 2008 and 2014 were followed up for 1 year.InterventionsCRT.Primary and secondary outcomes measuredSurvival, all-cause hospitalisations, length of stay, from which days alive and out of hospital (DAOH) were calculated.Results177patients were included, of whom eight died (4.5%) within 1 year of follow-up. Pre-CRT implantation, 83% of all patients had been hospitalised for a total 248 hospitalisation events. Following CRT, 47 patients (27%) were readmitted to hospital within 1 year (total of 98 admissions; pConclusionAfter CRT implant, patients with HF have greater DAOH with reduction of total hospitalisation and fewer hospital days. These results support CRT devices use as a treatment option for appropriate HF patients. DAOH represents an easily measured, patient-centred endpoint that may reflect effectiveness of interventions in future CRT studies.

Introduction: More effective methods for characterizing 3D electrical activity in human left atrium (LA) are needed to identify substrates/triggers and microreentrant circuit for paroxysmal atrial fibrillation (PAF). We describe a novel wavelet-based approach and wave-front centroid tracking that have been used to reconstruct regional activation frequency and electrical activation pathways from non-contact multi-electrode array. Methods: Data from 13 patients acquired prior to ablation for PAF with a 64 electrode noncontact catheter positioned in the LA were analysed. Unipolar electrograms were reconstructed at 2048 locations across each LA endocardial surface. Weighted fine- and coarse-scale electrograms were constructed by wavelet decomposition and combined with peak detection to identify atrial fibrillation (AF) activation frequency and fractionated activity at each site. LA regions with upper quartile AF frequencies were identified for each patient. On the other hand, a wave-front centroid tracking approach was introduced for this first time to detect macro-reentrant circuit during PAF. Results: The results employing wavelet-based analysis on atrial unipolar electrograms are validated by the signals recorded simultaneously via the contacted ablation catheter and visually tracking the 3D spread of activation through the interest region. Multiple connected regions of high frequency electrical activity were seen; most often in left superior pulmonary vein (10/12), septum (9/12) and atrial roof (9/12), as well as the ridge (8/12). The wave-front centroid tracking approach detects a major macro circuit involving LPVs, PLA, atrial floor, MV, septum, atrial roof and ridge. The regions with high frequency by wave-front tracking are consistent with the results using wavelet approach and our clinical observations. Conclusions: The wavelet-based technique and wave-front centroid tracking approach provide a robust means of extracting spatio-temporal characteristics of PAF. The approach could facilitate accurate identification of pro-arrhythmic substrate and triggers, and therefore, to improve success rate of catheter ablation for AF.

Temporary DDD pacing offers significant hemodynamic benefits in emergency management of bradyarrhythmias but is underused because of its complexity (two leads) and unreliability. Single lead VDD pacing with atrial sensing via a floating dipole is feasible, but atrial pacing is limited by high thresholds and phrenic nerve stimulation (PNS). Overlapping biphasic impulse (OLBI) stimulation may avoid these problems. The authors designed a single lead balloon-tipped catheter for temporary transvenous DDD pacing, incorporating noncontact atrial dipoles for OLBI stimulation. This catheter was deployed using fluoroscopic guidance in 74 patients (43 men, 31 women) with mean age 56.9 +/- 17.0 years. Pacing parameters were assessed at implantation and follow-up. The median procedural time was 6.6 (range 1.2-25.0) minutes and fluoroscopy time 1.9 (range 0.2-7.8) minutes. Stable VDD pacing was achieved in all cases. Atrial capture was achieved in 73 of 74 cases with both modes at maximum output but was restricted by PNS at outputs below atrial capture threshold in 3 of 74 cases with OLBI and 10 of 74 cases with standard bipolar mode (P = 0.04). At outputs > or = 1.0 V above atrial threshold, reliable DDD pacing without PNS was achieved and maintained in 67 (91%) of 74 patients in OLBI compared to 53 (72%) of 74 patients in bipolar mode (P = 0.003). Pacing parameters were stable during follow-up (median 53 hours, range 6-168 hours). In conclusion, the single lead catheter with OLBI stimulation allows temporary VDD and DDD pacing without PNS to be achieved in > 90% of patients. This rapid and convenient approach should facilitate DDD pacing in emergency settings.

Background We examined equity of access to implanted cardioverter defibrillators (ICDs) in New Zealand in 2010 by district health board (DHB), ethnicity and socioeconomic status. Methods All new ICD recipients in 2010 were examined according to home district health board, ethnicity according to the national health database, and socioeconomic status using the NZDep index. Results During 2010, 352 new ICDs were implanted nationwide, giving an overall implantation rate of 80.6/million. However, implant rates varied significantly across the 20 DHBs with the highest implant rate observed in Tairawhiti at 192.3/million, and the lowest at 22/million in the Nelson region. There was also significant variation in implant rate by ethnicity, with Maori ethnicity at an implant rate of 114/million, European patients at 83/million, Pacific Island patients at 47/million and Asian patients an implant rate of 32/million. There was no significant difference in number of implants by socioeconomic decile. Conclusions The variance in implantation rate by district health board and by ethnicity suggests that access to ICD therapy is not equitable in New Zealand. Investigation into causes of inequity of access is required.

Background: No long-term data on implantable cardioverter-defibrillators (ICDs) exist in Australasia. Aims: We examined all patients receiving a new ICD implant at Wellington Hospital between January 2001 and December 2005 to determine long-term outcomes in this patient population. Methods: Follow-up data were collected and Kaplan–Meier curves were constructed for survival and long-term outcomes, and Cox proportional hazard model was used for calculation of hazard ratio. Results: In the study period, 138 new ICDs were implanted, and the mean follow-up time was 84 ± 16 months. Patients were predominantly male (76%), 75% were European, 20% were Maori. Median age was 59 years (range 16–80 years). In 47% of patients, there was an ischaemic substrate. A secondary-prevention indication was present in 77%. The 7-year survival rate was 72%. No difference in mortality was observed between primary- and secondary-prevention groups. The 7-year appropriate therapy rate was 55%. The appropriate shock rate was greater in secondary prevention than in primary-prevention patients was observed (hazard ratio = 2.11, 95% confidence interval 1.16–3.85, P= 0.01). Over the study period, inappropriate therapy rate was 25%. This was more common in patients with prior atrial fibrillation (hazard ratio = 3.57, 95% confidence interval 1.80–7.09, P < 0.001). The median device longevity was 6.8 years. Conclusions: This is the first long-term follow-up study of ICD patients in New Zealand. We observed a low mortality rate when compared with other published registries, but a similar rate of both appropriate and inappropriate shock therapy.

Infection remains a significant problem for patients with cardiac-implantable electronic devices (CIEDs) but can be difficult to diagnose. We describe an unusual presentation of CIED infection in a patient with abandoned pacemaker leads. A 27-year-old male presented with facial flushing on upper but not lower limb exertion due to superior vena cava (SVC) obstruction, as well as pleuritic chest pain due to septic emboli. This was successfully treated with antibiotics and complete endovascular extraction of the pacemaker leads. Upper limb exertional facial flushing may be a useful clinical sign for the diagnosis of SVC obstruction. This case report also describes a rare presentation of CIED infection.

Objective Women have been under-represented in randomised clinical trials for primary prevention implantable cardioverter defibrillators (ICDs), and there are concerns about the efficacy of devices between genders. Our study aimed to investigate gender differences in the use of primary prevention ICD in patients with heart failure from the northern region of New Zealand. Methods Patients with heart failure with systolic dysfunction who received primary prevention ICD/cardiac resynchronisation therapy-defibrillator (CRT-D) in the northern region of New Zealand from 1 January 2007 to 1 June 2015 were included. Complications, mortality and hospitalisation events were reviewed. Results Of the 385 patients with heart failure implanted with ICD/CRT-D, women comprised 15.1% (n=58), and no change in utilisation of these devices was observed over the study period among women. Women were more likely to have non-ischaemic cardiomyopathy and have higher perioperative complications (8.6% vs 2.5%, P=0.02), with non-significant higher trend towards increased lead displacement (5.2% vs 1.8%, P=0.12). Women appeared to have lower all-cause (10.3% vs 18.7%, P=0.12), cardiovascular (5.2% vs 11.9%, P=0.13) and heart failure (3.5% vs 7.9%, P=0.22) mortalities but was not statistically significant. There were no gender differences in all-cause (70.7% vs 67%, P=0.58) or heart failure (19% vs 25%, P=0.32) readmissions. Conclusion Perioperative complications were significantly more common in women referred for ICD/CRT-D. Although there has been a significant increase in ICD implantation rates, gender differences in the use of these devices still exist in New Zealand, in keeping with the demographics of ischaemic heart disease and systolic dysfunction between genders.