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Journal of Cardiovascular... Apr 2022Ablation of papillary muscles (PMs) for refractory ventricular arrhythmias can often be challenging. The catheter approach and orientation during ablation may affect...
INTRODUCTION
Ablation of papillary muscles (PMs) for refractory ventricular arrhythmias can often be challenging. The catheter approach and orientation during ablation may affect optimal radiofrequency (RF) delivery. Yet, no previous study investigated the association between catheter orientation and PM lesion size. We evaluated ablation lesion characteristics with various catheter orientations relative to the PM tissue during open irrigated ablation, using a standardized, experimental setting.
METHODS
Viable bovine PM was positioned on a load cell in a circulating saline bath. RF ablation was performed over PM tissue at 50 W, with the open irrigated catheter positioned either perpendicular or parallel to the PM surface. Applied force was 10 g. Ablation lesions were sectioned and underwent quantitative morphometric analysis.
RESULTS
A catheter position oriented directly perpendicular to the PM tissue resulted in the largest ablation lesion volumes and depths compared with ablation with the catheter parallel to PM tissue (75.26 ± 8.40 mm vs. 34.04 ± 2.91 mm , p < .001) and (3.33 ± 0.18 mm vs. 2.24 ± 0.10 mm, p < .001), respectively. There were no significant differences in initial impedance, peak voltage, peak current, or overall decrease in impedance among groups. Parallel catheter orientation resulted in higher peak temperature (41.33 ± 0.28°C vs. 40.28 ± 0.24°C, p = .003), yet, there were no steam pops in either group.
CONCLUSION
For PM ablation, catheter orientation perpendicular to the PM tissue achieves more effective and larger ablation lesions, with greater lesion depth. This may have implications for the chosen ventricular access approach, the type of catheter used, consideration for remote navigation, and steerable sheaths.
Topics: Animals; Catheter Ablation; Catheters; Cattle; Heart Ventricles; Papillary Muscles; Therapeutic Irrigation
PubMed: 35133050
DOI: 10.1111/jce.15408 -
JACC. Clinical Electrophysiology Jan 2022
Topics: Catheter Ablation; Heart Ventricles; Humans; Microbubbles
PubMed: 35057979
DOI: 10.1016/j.jacep.2021.08.013 -
Kardiologia Polska 2022There are now more adults living with a history of congenital heart disease than there are children. Modern electrophysiologists must familiarize themselves with the...
There are now more adults living with a history of congenital heart disease than there are children. Modern electrophysiologists must familiarize themselves with the most common congenital lesions requiring electrophysiologic care as adults. Advancements in this field have been made most notably with high-resolution 3D imaging and electroanatomic mapping, left ventricular cannulation techniques, alternative pacing strategies, intracardiac echo, and transeptal access tools.
Topics: Adult; Child; Humans; Catheter Ablation; Heart Defects, Congenital; Arrhythmias, Cardiac; Heart Ventricles; Imaging, Three-Dimensional
PubMed: 36226762
DOI: 10.33963/KP.a2022.0235 -
Computers in Biology and Medicine Feb 2022Computational models of the heart built from cardiac MRI and electrophysiology (EP) data have shown promise for predicting the risk of and ablation targets for...
BACKGROUND
Computational models of the heart built from cardiac MRI and electrophysiology (EP) data have shown promise for predicting the risk of and ablation targets for myocardial infarction (MI) related ventricular tachycardia (VT), as well as to predict paced activation sequences in heart failure patients. However, most recent studies have relied on low resolution imaging data and little or no EP personalisation, which may affect the accuracy of model-based predictions.
OBJECTIVE
To investigate the impact of model anatomy, MI scar morphology, and EP personalisation strategies on paced activation sequences and VT inducibility to determine the level of detail required to make accurate model-based predictions.
METHODS
Imaging and EP data were acquired from a cohort of six pigs with experimentally induced MI. Computational models of ventricular anatomy, incorporating MI scar, were constructed including bi-ventricular or left ventricular (LV) only anatomy, and MI scar morphology with varying detail. Tissue conductivities and action potential duration (APD) were fitted to 12-lead ECG data using the QRS duration and the QT interval, respectively, in addition to corresponding literature parameters. Paced activation sequences and VT induction were simulated. Simulated paced activation and VT inducibility were compared between models and against experimental data.
RESULTS
Simulations predict that the level of model anatomical detail has little effect on simulated paced activation, with all model predictions comparing closely with invasive EP measurements. However, detailed scar morphology from high-resolution images, bi-ventricular anatomy, and personalized tissue conductivities are required to predict experimental VT outcome.
CONCLUSION
This study provides clear guidance for model generation based on clinical data. While a representing high level of anatomical and scar detail will require high-resolution image acquisition, EP personalisation based on 12-lead ECG can be readily incorporated into modelling pipelines, as such data is widely available.
Topics: Animals; Electrocardiography; Heart; Heart Ventricles; Humans; Myocardial Infarction; Swine; Tachycardia, Ventricular
PubMed: 34915331
DOI: 10.1016/j.compbiomed.2021.105061 -
Circulation. Arrhythmia and... Nov 2022Irreversible electroporation is an energy form utilizing high-voltage pulsed electric field, leading to cellular homeostasis disruption and cell death. Recently,...
BACKGROUND
Irreversible electroporation is an energy form utilizing high-voltage pulsed electric field, leading to cellular homeostasis disruption and cell death. Recently, irreversible electroporation has shown promising results for the treatment of cardiac arrhythmias. However, reversible and irreversible effects of pulsed electric field on cardiac myocytes remain poorly understood. Here, we evaluated the influence of a monophasic single electric pulse (EP) on the contractility, Ca homeostasis and recovery of cardiac myocytes.
METHODS
Isolated rat left ventricular myocytes were electroporated using single monophasic EP of different durations and voltages. Sarcomere length and intracellular Ca were simultaneously monitored for up to 20 minutes after EP application in Fura-2 loaded left ventricular myocytes. Lethal voltage thresholds were determined using 100 µs and 10 ms pulses and by discriminating cell orientation with respect to the electric field.
RESULTS
Electroporation led to an immediate increase in intracellular Ca which was dependent upon the voltage delivered to the cell. Intermediate-voltage EP (140 V, 100 µs) increased sarcomere shortening, Ca transient amplitude, and diastolic Ca level measured 1 minute post-EP. Although sarcomere shortening returned to pre-EP level within 5 minutes, Ca transient amplitude decreased further below pre-EP level and diastolic Ca level remained elevated within 20 minutes post-EP. Spontaneous contractions were observed after sublethal EP application but their frequency decreased progressively within 20 minutes. Lethal EP voltage threshold was lower in myocytes oriented perpendicular than parallel to the electric field using 100 µs pulses while an opposite effect was found using 10 ms pulses.
CONCLUSIONS
Sublethal EP affected rat left ventricular myocytes contractility and disrupted Ca homeostasis as a function of the EP voltage. Moreover, EP-induced lethality was preceded by a large increase in intracellular Ca and was dependent upon the EP duration, amplitude and left ventricular myocytes orientation with respect to the electric field. These findings provide new insights into the effect of pulsed electric field on cardiac myocytes.
Topics: Rats; Animals; Myocytes, Cardiac; Calcium; Heart Ventricles; Electroporation; Homeostasis
PubMed: 36306333
DOI: 10.1161/CIRCEP.122.011131 -
Journal of Cardiovascular... May 2017Arrhythmia ablation with current techniques is not universally successful. Inadequate ablation lesion formation may be responsible for some arrhythmia recurrences....
BACKGROUND
Arrhythmia ablation with current techniques is not universally successful. Inadequate ablation lesion formation may be responsible for some arrhythmia recurrences. Periprocedural visualization of ablation lesions may identify inadequate lesions and gaps to guide further ablation and reduce risk of arrhythmia recurrence.
METHODS
This feasibility study assessed acute postprocedure ablation lesions by MRI, and correlated these findings with clinical outcomes. Ten pediatric patients who underwent ventricular tachycardia ablation were transferred immediately postablation to a 1.5T MRI scanner and late gadolinium enhancement (LGE) imaging was performed to characterize ablation lesions. Immediate and mid-term arrhythmia recurrences were assessed.
RESULTS
Patient characteristics include median age 14 years (1-18 years), median weight 52 kg (11-81 kg), normal cardiac anatomy (n = 6), d-transposition of great arteries post arterial switch repair (n = 2), anomalous coronary artery origin post repair (n = 1), and cardiac rhabdomyoma (n = 1). All patients underwent radiofrequency catheter ablation of ventricular arrhythmia with acute procedural success. LGE was identified at the reported ablation site in 9/10 patients, all arrhythmia-free at median 7 months follow-up. LGE was not visible in 1 patient who had recurrence of frequent premature ventricular contractions within 2 hours, confirmed on Holter at 1 and 21 months post procedure.
CONCLUSIONS
Ventricular ablation lesion visibility by MRI in the acute post procedure setting is feasible. Lesions identifiable with MRI may correlate with clinical outcomes. Acute MRI identification of gaps or inadequate lesions may provide the unique temporal opportunity for additional ablation therapy to decrease arrhythmia recurrence.
Topics: Adolescent; Age Factors; Catheter Ablation; Child; Child, Preschool; Feasibility Studies; Female; Heart Ventricles; Humans; Infant; Magnetic Resonance Imaging; Male; Predictive Value of Tests; Prospective Studies; Recurrence; Risk Factors; Tachycardia, Ventricular; Time Factors; Treatment Outcome
PubMed: 28245348
DOI: 10.1111/jce.13197 -
JACC. Clinical Electrophysiology May 2023Ultra-low temperature cryoablation (ULTC) using near-critical nitrogen (-196ºC) has been shown to produce durable, contiguous, transmural lesions in ventricles of... (Review)
Review
Ultra-low temperature cryoablation (ULTC) using near-critical nitrogen (-196ºC) has been shown to produce durable, contiguous, transmural lesions in ventricles of animal models. This report summarizes acute experience with ULTC in the first-ever 13 patients with recurrent monomorphic ventricular tachycardias (VTs) of both ischemic cardiomyopathy and nonischemic etiologies enrolled in the CryoCure-VT (Cryoablation for Monomorphic Ventricular Tachycardia; NCT04893317) clinical trial. After an average of 9.6 ± 4.6 endocardial ULTC lesions per patient, no clinical ventricular tachycardias were inducible in 91% of patients. Two procedure-related serious adverse events recorded in 2 patients resolved post-procedurally without clinical sequelae. Further investigation of both acute and chronic outcomes is warranted and ongoing.
Topics: Animals; Humans; Cryosurgery; Temperature; Tachycardia, Ventricular; Heart Ventricles; Endocardium
PubMed: 36752466
DOI: 10.1016/j.jacep.2022.11.017 -
JACC. Clinical Electrophysiology Mar 2017This study sought to evaluate an investigational catheter that incorporates 3 microelectrodes embedded along the circumference of a standard 3.5-mm open-irrigated... (Comparative Study)
Comparative Study
OBJECTIVES
This study sought to evaluate an investigational catheter that incorporates 3 microelectrodes embedded along the circumference of a standard 3.5-mm open-irrigated catheter.
BACKGROUND
Mapping resolution is influenced by both electrode size and interelectrode spacing. Multielectrode mapping catheters enhance mapping resolution within scar compared with standard ablation catheters; however, this requires the use of 2 separate catheters for mapping and ablation.
METHODS
Six swine with healed infarction and 2 healthy controls underwent mapping of the left ventricle using a THERMOCOOL SMARTTOUCH SF catheter with 3 additional microelectrodes (0.167 mm) along its circumference (Qdot, Biosense Webster, Diamond Bar, California). Mapping resolution in healthy and scarred tissue was compared between the standard electrodes and microelectrodes using electrogram characteristics, cardiac magnetic resonance, and histology.
RESULTS
In healthy myocardium, bipolar voltage amplitude was similar between the standard electrodes and microelectrodes, with a fifth percentile of 1.19 and 1.30 mV, respectively. In healed infarction, the area of low bipolar voltage (defined as <1.5 mV) was smaller with microelectrodes (16.8 cm vs. 25.3 cm; p = 0.033). Specifically, the microelectrodes detected zones of increased bipolar voltage amplitude, with normal electrogram characteristics occurring at the end of or after the QRS, consistent with channels of preserved subendocardium. Identification of surviving subendocardium by the microelectrodes was consistent with cardiac magnetic resonance and histology. The microelectrodes also improved distinction between near-field and far-field electrograms, with more precise identification of scar border zones.
CONCLUSIONS
This novel catheter combines high-resolution mapping and radiofrequency ablation with an open-irrigated, tissue contact-sensing technology. It improves scar mapping resolution while limiting the need for and cost associated with the use of a separate mapping catheter.
Topics: Animals; Body Surface Potential Mapping; Catheter Ablation; Cicatrix; Electrocardiography; Electrophysiologic Techniques, Cardiac; Endocardium; Heart Ventricles; Magnetic Resonance Spectroscopy; Male; Microelectrodes; Myocardial Infarction; Myocardium; Prospective Studies; Swine; Tachycardia, Ventricular
PubMed: 29759516
DOI: 10.1016/j.jacep.2016.12.016 -
Medicine Feb 2021Hemodynamically-instable ventricular arrhythmias (VAs) are rare in patients with pulmonary hypertension (PH). To the best of our knowledge, only 1 case has been reported...
INTRODUCTION
Hemodynamically-instable ventricular arrhythmias (VAs) are rare in patients with pulmonary hypertension (PH). To the best of our knowledge, only 1 case has been reported so far. Moreover, the pathogenesis of this kind of arrhythmia remains obscured and its treatment is challenging. Here we report another case and presented the substrate for VAs initiation and therapeutic effect of radiofrequency ablation.
PATIENT CONCERNS
This is a 57-year-old man who presented paroxysmal palpitation associated with presyncope at rest. Surface electrocardiogram (ECG) revealed frequent ventricular premature contractions and non-sustained ventricular tachycardia when symptoms occurred. He also had a history of severe PH which was secondary to atrial septal defect and partial anomalous pulmonary venous drainage and suffered from obvious dyspnea when climbing stairs World Health Organization Class III (WHO Class III).
DIAGNOSIS
Hemodynamically-instable VAs associated with severe PH.
INTERVENTION
Echocardiography revealed enlargement of right ventricle (right ventricle [RV]: 43 mm). Electrophysiological examination showed the origin of VAs is next to a small low-voltage zone of RV. Radiofrequency delivery at the origin successfully terminated VAs without occurrence of complication.
OUTCOME
The patient was free from arrhythmias and got an improvement of exercise tolerance, just with mild dyspnea when climbing stairs World Health Organization Class II (WHO class II), during six-month follow up.
LESSONS
This case suggests the low-voltage zone of remodeled RV, which may be secondary to increased pulmonary artery pressure, serves as the substrate for VAs initiation in patient with PH. Radiofrequency ablation can successfully terminate VAs and the termination of VAs can significantly improve the patient's impaired exercise tolerance.
Topics: Echocardiography; Electrophysiologic Techniques, Cardiac; Heart Ventricles; Humans; Hypertension, Pulmonary; Male; Middle Aged; Radiofrequency Ablation; Ventricular Premature Complexes; Ventricular Remodeling
PubMed: 33663121
DOI: 10.1097/MD.0000000000024896 -
Circulation. Arrhythmia and... Sep 2021[Figure: see text].
[Figure: see text].
Topics: Body Surface Potential Mapping; Catheter Ablation; Connectin; DNA; DNA Mutational Analysis; Female; Follow-Up Studies; Heart Ventricles; Humans; Magnetic Resonance Imaging, Cine; Male; Middle Aged; Mutation; Retrospective Studies; Tachycardia, Ventricular
PubMed: 34315225
DOI: 10.1161/CIRCEP.121.010006