Variance in tissue thermodynamics during cryothermal ablation depends on the distance from balloon and peri-balloon blood flow leaks. This information may be useful for successful PVI without severe complications.
Electromagnetic interference produced by medical equipment can interact with implanted cardiac devices such as pacemakers and implantable cardioverter-defibrillators. The most commonly observed interaction is in the operating room with electrosurgery. The risk of interactions can often be mitigated by close communication between the cardiac-device specialist and the anesthesiology/surgical team to develop a patient-specific strategy that accounts for factors such as type of device, type of surgery, and whether the patient is pacemaker dependent. Although magnetic resonance imaging should generally not be used in patients with implanted cardiac devices, several published guidelines provide strategies and recommendations for managing risks if magnetic resonance imaging is required with no suitable diagnostic alternatives. Other common sources of electromagnetic interference in the medical environment are ionizing radiation and left ventricular assist devices.
BackgroundRecently, pulmonary vein isolation (PVI) using the second generation cryoballoon, introduced as a therapy for patients with drug-refractory atrial fibrillation, has shown better outcomes than with the first generation cryoballoon. [1][2][3][4][5] However, some questions about the second generation cryoballoon remain. Several studies in cryobiology have shown that prolongation of freeze duration produces a greater destructive effect in noncardiac tissue. 6,7 However, ablation duration to achieve acute and long-term PVI is still debatable. It is also unclear how different sized balloons (23 and 28 mm) should be used, as the impact of the balloon size on tissue and balloon temperature profiles and ablative lesion size have not been studied. Information on the effects of ablation duration and balloon size is required to achieve high PVI success rates without severe complications using the second generation cryoballoon.The purpose of this study was to investigate the impact of ablation duration and balloon size on tissue and balloon thermodynamics, acute and chronic PVI success rates, complications, and chronic histological changes of the PV and left atrium (LA). Methods GeneralThis study was designed to compare the ablation effect and safety of different ablation durations (3 versus 4 minutes) and different balloon sizes (23 versus 28 mm) in an in vivo model. Twenty-six dogs underwent PVI using second generation cryoballoon. Animal PreparationThe protocol was approved by Mayo Foundation Institutional Animal Care and Use Committee. Dogs (30.3±2.5 kg) were anesthetized with intravenous ketamine and diazepam, intubated, and maintained on 1% to 3% isoflurane. The surface ECG, body temperature, and blood pressure were monitored. Tissue Temperature MonitoringTissue temperatures were monitored by implanted thermocouples, as reported previously. 8,9 All dogs underwent left/right thoracotomy for access to the superior/inferior PVs. The pericardium was opened to © 2015 American Heart Association, Inc. Original Article Circ Arrhythm ElectrophysiolBackground-The differences in ablation characteristics of freezing time and balloon size using second generation cryoballoon are still unknown. Methods and Results-Twenty-six dogs underwent pulmonary vein (PV) isolation. Balloon and tissue temperatures (left atrial-PV junction, phrenic nerve, and internal esophagus) were monitored. The ablation duration was randomized to either 3 or 4 minutes, which did not show significant differences in temperature profiles, PV isolation success rate, complications, or histological changes. Twenty dogs underwent cryoablation using 28-mm cryoballoon, 6 dogs were done using the 23-mm cryoballoon. Positioning of the 23-mm cryoballoon was more distal in the PV, which resulted in better PV occlusion. Temperature profiles showed lower temperatures in the 23-mm cryoballoon than in the 28-mm cryoballoon
The number of patients with cardiovascular implantable electronic devices (CIEDs), such as permanent pacemakers and implantable cardioverter-defibrillators, is dramatically rising due to an aging population and recent clinical trials showing benefits in mortality and morbidity. Coupled with this increase in the number of patients with CIEDs is the proliferation of technology that emits electromagnetic signals, which can potentially interfere with CIED function through electromagnetic interference (EMI). Despite continuous efforts of manufacturers to create ''EMI-proof'' CIEDs, adverse events from EMI still occur. Physicians caring for patients with CIEDs should be aware of potential sources of EMI and appropriate management options. This 2-part review aims to provide a contemporary overview of the current knowledge regarding risks attributable to EMI interactions from the most common nonmedical (Part I) and medical (Part II) sources. Device Responses to Electromagnetic Interference Before discussing EMI from specific sources, it is important to emphasize that the clinical consequences of the interaction will depend on the type of interaction, type of device, and patient characteristics (Table 2). All
Background— Particle therapy, with heavy ions such as carbon-12 ( 12 C), delivered to arrhythmogenic locations of the heart could be a promising new means for catheter-free ablation. As a first investigation, we tested the feasibility of in vivo atrioventricular node ablation, in Langendorff-perfused porcine hearts, using a scanned 12C beam. Methods and Results— Intact hearts were explanted from 4 (30–40 kg) pigs and were perfused in a Langendorff organ bath. Computed tomgraphic scans (1 mm voxel and slice spacing) were acquired and 12 C ion beam treatment planning (optimal accelerator energies, beam positions, and particle numbers) for atrioventricular node ablation was conducted. Orthogonal x-rays with matching of 4 implanted clips were used for positioning. Ten Gray treatment plans were repeatedly administered, using pencil beam scanning. After delivery, positron emission tomography-computed tomgraphic scans for detection of β + ( 11 C) activity were obtained. A 12 C beam with a full width at half maximum of 10 mm was delivered to the atrioventricular node. Delivery of 130 Gy caused disturbance of atrioventricular conduction with transition into complete heart block after 160 Gy. Positron emission computed tomgraphy demonstrated dose delivery into the intended area. Application did not induce arrhythmias. Macroscopic inspection did not reveal damage to myocardium. Immunostaining revealed strong γH2AX signals in the target region, whereas no γH2AX signals were detected in the unirradiated control heart. Conclusions— This is the first report of the application of a 12 C beam for ablation of cardiac tissue to treat arrhythmias. Catheter-free ablation using 12C beams is feasible and merits exploration in intact animal studies as an energy source for arrhythmia elimination.
Syncope and palpitations are common complaints that all physicians confront during daily clinical practice. Single center and multicenter cohort studies have found that syncope accounts for 1%-3% of emergency department evaluations and that palpitations are the primary symptom for approximately 16% of patients who arrive at an outpatient clinic with a cardiac complaint. For both conditions, women make up approximately 60% of the cohorts. In general, the evaluation of both syncope and palpitations can be challenging because of the heterogeneity of causes and, consequently, the variability of clinical outcomes, ranging from a single isolated event with no effect on morbidity and mortality to the first sign of a potentially life-threatening problem and sudden cardiac death. For all women with syncope or palpitations, the history, physical examination, and a baseline electrocardiogram (ECG) form the basis of the initial workup and focus on identifying patients with cardiovascular abnormalities who are at the highest risk for sudden cardiac death. More advanced tests must be chosen using a problem-specific approach, but generally, documentation of the cardiac rhythm during symptoms is critical for all patients with syncope or palpitations. Although the diagnostic testing strategy is generally similar for men and women, gender-related differences in treatment response have been identified. Antiarrhythmic medications, such as dofetilide and sotalol, that prolong the QT interval are more likely to be associated with proarrhythmia in women. In addition, higher complication rates for invasive cardiac procedures, such as device implantation, are observed in women.
A 69-year-old woman with a 10-year history of paroxysmal atrial fibrillation was initially treated with propafenone and amiodarone. Four years ago her arrhythmia burden worsened and she developed recurrent episodes of symptomatic persistent atrial fibrillation. After several cardioversions, she was referred to our institution for radiofrequency catheter ablation. Her amiodarone was discontinued, and 1 year ago she underwent radiofrequency catheter ablation using a pulmonary vein antral isolation approach. Unfortunately, she developed recurrent atrial fibrillation and remained extremely symptomatic despite adequate control of her heart rate. Six months ago, she underwent a second radiofrequency catheter ablation procedure. Electrophysiology study revealed recurrent conduction between all four pulmonary veins and the left atrium, and the veins were reisolated and linear ablations were performed on the roof of the left atrium and the cavotricuspid isthmus. After the ablation, no atrial tachycardia or atrial fibrillation could be induced with aggressive pacing protocols. Unfortunately, she developed recurrent persistent atrial fibrillation within 1 week of the procedure. Four months later she underwent cardioversion with initiation of dofetilide. Two days after starting dofetilide she developed atypical atrial flutter and was referred for a third electrophysiology study.Surface ECG revealed upright P waves in leads V 1 and V 2 but were poorly seen in the other leads. At electrophysiology study, a circular mapping catheter placed in the four pulmonary veins demonstrated no electrical activity during atrial tachycardia, confirming adequate pulmonary vein isolation. At baseline the atrial tachycardia had stable alternating cycle lengths of 365 ms and 410 ms. Initial pacing maneuvers from the anterolateral right atrium and the proximal and distal coronary sinus yielded post-pacing intervals with long return cycle lengths. In addition, constant fusion and progressive fusion during pacing from the right atrium and the coronary sinus were observed. In order to delineate the tachycardia circuit a 64-electrode basket catheter was placed in the posterior left atrium (Figure 1). At baseline, electrograms could be recorded for 318 ms of the 363-ms and 411-ms cycle lengths (88% and 77% respectively) over a large area in the posterior left atrium. The deflection of the P wave corresponded to activation of the superior and anterior portions of the left atrium.We mapped the tachycardia circuit by identifying the initial site of cycle length change that localized the critical isthmus to the posterior roof of left atrium near the right superior pulmonary vein (Figure 2). When the mapping catheter was moved septally or laterally, split potentials suggestive of a line of conduction block were observed and a 20-electrode catheter revealed a fractionated electrogram that was the first site of cycle length change. Unfortunately, adequate capture could not be obtained despite pacing at maximal outputs from either electrode pair 17 and 18 of...
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