Radiofrequency Lesions Research Articles

Utilising the pericardial CO2 insufflation technique to facilitate endo-epicardial AF ablation, achieving linear radiofrequency lesion sets, for persistent atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background High rates of persistent atrial fibrillation (PsAF) recurrence have been attributed to conduction gaps, non-transmural linear lesion sets and epicardial substrate. Hybrid thorascopic endo-epicardial AF ablation has been shown to reduce PsAF recurrence when compared to endocardial ablation alone, however with higher complication rates. Aim We propose that the percutaneous pericardial CO2 insufflation technique to access the pericardial space can be safely and effectively used for epicardial mapping and ablation of the left atrium (LA). Methods In a single centre, 15 patients with PsAF (6 with longstanding PsAF) and previous pulmonary vein isolation (PVI), underwent concurrent endo-epicardial AF ablation, using the subxiphoid percutaneous pericardial CO2 insufflation technique, whilst on uninterrupted anticoagulation. Endo-epicardial geometry and bipolar voltage maps were undertaken, and endocardial LA ablation performed comprising a roof, inferior and anterior mitral line (AML) (target LSI 5 for the inferior line and 6 on the roof and AML). If required, additional epicardial ablation was undertaken to establish PVI and linear lesion block. Results Epicardial access was achieved in all patients without acute bleeding complication. Epicardial mapping of the LA, in both transverse and oblique pericardial sinuses, was successful in all patients (Figure 1A, B). Excluding one roof line, all other linear lesions were blocked (44/45). Endocardial ablation alone achieved block in 67% (10 of 15) of roof lines, 87% (13 of 15) of inferior lines and 27% (4 of 15) of AMLs despite extensive endocardial ablation. Of AMLs requiring epicardial ablation, in 91% (10/11) block was achieved with ablation on the upper third of AML via the transverse sinus (Figure 1C). Epicardial ablation directly on the roof line via the transverse sinus was required to achieve block in 3 cases, and block achieved remotely on the upper third of the AML in another. Epicardial ablation on the mid inferior line was required in 2 cases to achieve block. Six patients had arrhythmia recurrence during the blanking period with 5 patients requiring DCCV and 1 patient chemically cardioverting. With a mean follow up time of 225 days, 2 patients have had paroxysmal self-terminating episodes of atrial arrhythmia with all patients off anti-arrhythmic medication. Conclusion Use of the subxiphoid percutaneous pericardial CO2 insufflation technique to achieve epicardial access for LA mapping and ablation is feasible and safe whilst on uninterrupted anticoagulation. Limited success in ablation for PsAF beyond PVI may be due to difficulty in creating trans-mural linear lesions. Epicardial ablation can be safely performed to achieve linear block in the roof, anterior and inferior LA. Epicardial fibrous structures such as the septopulmonary bundle and Bachmann’s bundle likely contribute to difficulty blocking roof lines and AMLs endocardially.

Single-center outcome after ablation of atrial fibrillation using very high-power short duration pulmonary vein isolation

Abstract Funding Acknowledgements Type of funding sources: None. Background Catheter ablation of atrial fibrillation is (AF) an established second line therapy for patients with symptomatic paroxysmal (PAF) and persistent AF (persAF). Novel ablation catheters with integrated thermocouples allow fast application of radiofrequency lesions with powers up to 90W. We aimed to describe primary and secondary outcomes after very high-power short duration (vHPSD) ablation. Methods 126 consecutive patients (78 PAF, 43 persAF, 5 longstanding persistent AF) underwent pulmonary vein isolation (PVI) using the QDOT Micro Catheter (Biosense Webster) with the ablation mode QMODE+ (90W, 4s, interlesion distance ≤4mm anterior, ≤6mm posterior). Results Mean age was 62±9 years, 33% were female, median CHA2DS2-VASc Score was 2 (0, 7). Median follow up duration was 204 (14, 461) days. 30% of patients had additional ablation of typical right atrial flutter. Primary success rate to achieve pulmonary vein isolation was achieved in all patients, no catheter-related complications (e.g., charring, steam pop) occurred. First pass isolation of all 4 PVs was achieved in 48% of patients, re-ablations were necessary in the carina regions (right: 37% of cases, left: 29%) and ridge (14%). Median procedure for PVI only were 102 (45-210) minutes. Arrhythmia-free survival was 79,6% (see Figure 1). Eight patients underwent re-do procedures during follow-up showing most commonly showing gaps in the right inferior PV (63%) and ridge (50%). Conclusion Very high-power short duration ablation allows safe and quick pulmonary vein isolation. However, first pass isolation rate is low due to gaps in the carina regions. Arrhythmia-free survival is comparable to other pulmonary vein isolation techniques. Figure 1: Left panel: Sample image of a vHPSD-PVI, posterior view of the left atrium. Right panel: Single procedure arrhythmia-free survival after vHPSD-PVI.

Free-breathing joint bright- and black-blood cardiovascular magnetic resonance imaging for the improved visualization of ablation-related radiofrequency lesions in the left ventricle

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): This research was supported by funding from the French National Research Agency under grant agreements Equipex MUSIC ANR-11-EQPX-0030, ANR-21-CE17-0034-01 and Programme d’Investissements d’Avenir ANR-10-IAHU04-LIRYC, and from the European Council under grant agreement ERC n715093. AB acknowledges a Lefoulon-Delalande Foundation fellowship administered by the Institute of France. Background Bright-blood late gadolinium-enhanced (LGE) cardiovascular magnetic resonance (CMR) imaging can identify the sites that were ablated during prior ablation procedures (1). However, myocardial lesions visualization is often impaired by the poor contrast at the blood-scar interface on conventional bright-blood-LGE images. Purpose To assess the performance of a novel joint bright- and black-blood LGE (SPOT) technique to visualize myocardial lesions post ablation. Methods Three sheep (age 2 years, body weight 51.6 kg) underwent radiofrequency ablation at multiple endocardial and epicardial sites. The animals were imaged 3 months later on a 1.5-T CMR scanner using conventional post-contrast bright-blood LGE (PSIR) (1) and the proposed SPOT (2) sequences. The SPOT sequence sampled the data to simultaneously generate a black-blood image (for scar visualization) and a bright-blood image (for scar localization) in a free-breathing 2-dimensional multi-slice scan (2). A coloured representation of myocardial scarring was then generated through image fusion. A reader graded the relative scar-to-myocardium, scar-to-blood, and blood-to-myocardium contrasts and the presence of LGE on all datasets. Results Compared with the reference bright-blood LGE images, the average scar-to-myocardium relative contrast in the SPOT images significantly increased by 102.5% to 8.1±4.4 (P<0.01). Similarly, a significant increase in scar-to-blood relative contrast (0.4±0.6 vs. 7.6±4.9, P<0.01) was observed. Owing to the nulling of both blood and normal myocardium signal, a significant decrease in blood-to-myocardium relative contrast (2.5±1.8 vs. 0.2±0.4, P<0.01) was observed with SPOT. A total of 7 and 12 lesions could be identified on conventional bright-blood LGE and proposed SPOT images, respectively (Figure). Conclusion The higher scar-to-blood relative contrast with SPOT imaging enables the improved visualization of myocardial lesions post radiofrequency ablation. SPOT offers a promising technology for the non-invasive assessment of myocardial injuries post ablation.

PO-710-01 “ELECTRODE TISSUE COUPLING” IS A NEW MAIN DETERMINANT OF RF LESION CREATION - EXPERIENCE FROM A CARDIAC ANIMAL MODEL

Radiofrequency (RF) current is a classic ablation technology used in the EP lab. By now it is assumed that RF lesion seize is mainly determined by RF power, duration and contact force. This ex vivo animal model study shows that a new parameter - “electrode tissue coupling” (ETC) - plays an additional major role in RF lesion creation. The ETC level describes the amount of electric contact between the RF electrode and cardiac tissue: In minor ETC levels, only the distal electrode connects to tissue. In full ETC levels, the whole RF electrode is embedded in cardiac tissue. The aim of this study was to investigate the influence of ETC levels on RF-lesion size. RF-lesions were created using an ex vivo porcine cardiac model. The experimental setup consisted of a saline-filled container, a dispersive electrode, a heated thermostat and a circulation pump to imitate in vivo conditions. Global impedance was kept at 120 Ohm as well as the temperature at 37°C. RF-lesions were created using identic values of RF duration and contact force. A RF power of 20W, 30W, 40W, and 50W was used. The ETC levels were varied between minor and full coupling. All parameters (power, temperature, global and local impedance, contact force, lesion size) were measured during application of RF-current, enabling real-time correlation of RF parameters and lesion size. In total, 1923 measurements during application of RF-current were analyzed. In ETC III (full tissue coupling), lesions became significantly wider and deeper. In 20W ablations, lesion diameters were significantly (1.68 fold) larger when applying ETC III instead of ETC I. This relation was found in variations of RF parameters. Baseline local impedance and local impedance drop showed a high correlation with selected ETC levels. The average baseline local impedance in ETC I was 207.2 Ohm, compared to 267.3 Ohm in ETC III (p < 0.01). In addition to by now known parameters (power, duration, contact force), ETC is a main determinant of lesion size. Higher ETC levels result in higher amounts of RF current going into adjacent tissue instead of current dissipation into the blood pool. In clinical practice, the ETC level can be predicted by baseline local and global impedance. Observation of these parameters should become clinical practice during RF ablation.

PO-681-08 REDUCED PROCEDURAL DURATION WITH PROACTIVE ESOPHAGEAL COOLING DURING LEFT ATRIAL ABLATION: A MULTICENTER ANALYSIS

Reductions in left atrial ablation procedure duration can improve lab efficiency, patient satisfaction, and overall safety. Pauses and interruptions of lesion placement due to luminal esophageal temperature (LET) rises during pulmonary vein isolation (PVI) can disrupt workflow and increase procedure time. Proactive esophageal cooling eliminates the need for lesion interruption by preventing heat stacking and obviating the need for temperature monitoring. Avoiding premature pauses of radiofrequency (RF) lesion placement may also reduce PVI procedure duration.

PO-624-08 METHOD FOR TISSUE-TRANSDUCER CONTACT-SENSING OF A HIGH-INTENSITY ULTRASOUND ABLATION CATHETER

High intensity ultrasound (US) ablation overcomes limitations of shallow radiofrequency lesion depth. The directivity of the US field necessitates a method to confirm contact and orthogonal orientation to tissue.

Optimized radiofrequency lesions through local impedance guidance for effective CTI ablation in right atrial flutter.

Although radiofrequency (RF) catheter ablation of cavo-tricuspid isthmus (CTI) is an established treatment for typical right atrial flutter (RAFL), it remains to be established whether local tissue impedance (LI) is able to predict effective CTI ablation and what LI drop values during ablation should be used to judge a lesion as effective. We aimed to investigate the ability of LI to predict ablation efficacy in patients with RAFL. RF delivery was guided by the DirectSense™ algorithm. Successful single RF application was defined according to a defragmentation of atrial potentials (DAP), reduction of voltage (RedV) by at least 80% or changes on unipolar electrogram (UPC). The ablation endpoint was the creation of bidirectional conduction block (BDB) across the isthmus. 392 point-by-point RF applications were analyzed in 48 consecutive RAFL patients. The mean baseline LI was 105.4±12Ω prior to ablation and 92.0±11Ω after ablation (p<0.0001). According to validation criteria, absolute drops in impedance were larger at successful ablation sites than at ineffective ablation sites (DAP: 17.8±6Ω vs. 8.7±4Ω; RedV: 17.2±6Ω vs. 7.8±5Ω; UPC: 19.6±6Ω vs. 10.1±5Ω, all p<0.0001). LI drop values significantly increased according to the number of criteria satisfied (ranging from 7.5Ω to 19.9). BDB was obtained in all cases. No procedure-related adverse events were reported. A LI-guided approach to CTI ablation was safe and effective in treating RAFL. The magnitude of LI drop was associated with effective lesion formation and BDB and could be used as a marker of ablation efficacy. Catheter Ablation of Arrhythmias with a High-Density Mapping System in Real-World Practice (CHARISMA). URL: http://clinicaltrials.gov/ Identifier: NCT03793998.

Safety of Conventional and Pulsed Radiofrequency Lesions of the Dorsal Root Entry Zone Complex (DREZC) for Interventional Pain Management: A Systematic Review.

Study DesignSystematic literature review.ObjectiveThe goal of this systematic review is to assess the clinical safety and potential complications of conventional and pulsed radiofrequency ablations targeting dorsal root entry zone complex (DREZC) components in the treatment of chronic pain.BackgroundThere is a growing popularity for the use of radiofrequency ablation (RFA) techniques targeting DREZC components by pain management physicians for an increasing variety of indications. To date, we lack a systematic review to describe the safety and the type of complications associated with these procedures.MethodsThis was a systematic literature review. This systematic search was limited to peer-reviewed literature using “radiofrequency ablation” as a search keyword using PubMed’s database for manuscripts published between inception and December 2020. s that involved the application of radiofrequency currents, of any modality, to DREZC components for the treatment of pain were included for full-text review. Search was limited to original data describing clinical outcomes following RFA performed for pain indications only, involving the DREZC components outlined above, in human subjects, and written in English. The primary outcomes were complications associated with conventional RFA and pulsed radiofrequency ablation (PRF). Complications were categorized as type 1 (persistent neurological deficits or other serious adverse events, defined as any event that resulted in permanent of prolonged injury; type 2 (transient neuritis or neurological deficits, or other non-neurological non-minor adverse event); type 3 (minor adverse events (e.g., headache, soreness, bruising, etc.).ResultsOf the 62 selected manuscripts totaling 3157 patients, there were zero serious adverse events or persistent neurological deficits reported. A total of 36 (1.14%) transient neurological deficits, cases of transient neuritis, or non-minor adverse events like uncomplicated pneumothorax were reported. A total of 113 (3.58%) minor adverse events were reported (bruising, transient site soreness, headache).ConclusionsThis systematic review indicates that the use of RFA lesion of the DREZC for interventional pain management is very safe. There were no serious adverse effects with a sizable sample of randomized controlled trial (RCT), prospective observational, and retrospective studies.

Ultrasound-guided continuous radiofrequency ablation of the suprascapular nerve for chronic shoulder pain secondary to osteoarthritis: a retrospective cohort study.

The objective of this study is to retrospectively evaluate the use of ultrasound-guided continuous radiofrequency (CRF) lesioning of the suprascapular nerve for treating chronic shoulder pain, due to osteoarthritis. We describe a modified distal and selective ablation technique in the spinoglenoid notch, with motor and sensory stimulation, which protects the motor branch of the nerve from ablation. A retrospective analysis was performed of patients, who underwent ultrasound-guided CRF lesioning of the suprascapular nerve from October 2013 to January 2020. During the procedure, the CRF electrode is placed in the spinoglenoid notch, at the distal suprascapular nerve capsular branch. Motor and sensory stimulations are used to confirm the position. CRF lesioning is applied up to three times, at 3 different points, for 1 min each time, at 80° C. In total, 127 first CRF suprascapular nerve lesioning procedures were performed on 101 patients with chronic shoulder pain secondary to osteoarthritis. One hundred nineteen diagnostic ultrasound-guided suprascapular nerve corticosteroid injections were performed prior to ablation. Mean pre-injection Visual Analogue Scale pain score (VAS) was 8.3, with post-injection VAS score of 4.4 at 24 h and 4.5 at 2 weeks. Mean pre-CRF lesioning VAS pain score was 7.7 with post-CRF lesioning VAS score of 4.4 at 24 h and 4.5 at 2 weeks. Ultrasound-guided CRF lesioning of the suprascapular nerve in the spinoglenoid notch is a safe treatment for chronic osteoarthritic shoulder pain, with repeat treatments infrequently required. It is associated with significant improvement in VAS pain scores. • Ultrasound-guided continuous radiofrequency lesioning of the suprascapular nerve in the spinoglenoid notch is a safe treatment for chronic shoulder pain in degenerative disease, with repeat treatments infrequently required. • The procedure is performed under ultrasound guidance, without the use of ionising radiation.

An Unusual Case of Dense Mitral Annular Calcification in a Young with Plethora of Mitral Annular Premature Ventricular Complexes

We report a rare case of dense mitral annular calcification in a 26-year-old male presenting with recurrent palpitation for the last year with a plethora of mitral annular premature ventricular complexes (PVCs). PVCs had right bundle branch block morphology, were notched in inferior leads with negative QRS complexes in aVL suggestive of likely origin from the lateral mitral annulus. Patients with PVCs from mitral annulus are usually advised to undergo cardiac magnetic resonance imaging to localize the site of subtle mitral annular calcification and plan subsequent delivery of radiofrequency lesions at the same site during radiofrequency ablation. Dense calcification of the lateral mitral annulus is extremely rare to encounter in such a young age of below 30 years without the presence of any predisposing risk factors for calcification. Our case is the first illustration of dense mitral annular calcification secondary to the plethora of mitral annular PVCs in a symptomatic young person below the age of 30 years. PVCs-induced excessive local excursion with wear and tear phenomenon and secondary dystrophic calcification may be the plausible explanation behind this interesting presentation.

Commentary: Combined Unilateral Radiofrequency Lesioning of the Motor Thalamus, Field of Forel, and Zona Incerta: A Series of Cases With Dystonia.

Commentary: Combined Unilateral Radiofrequency Lesioning of the Motor Thalamus, Field of Forel, and Zona Incerta: A Series of Cases With Dystonia.

Effectiveness of radiofrequency ablation for treatment of plantar fasciitis.

Plantar fasciitis is the most common cause of heel pain. Pain can be persistent in some patients and interrupt daily activities and sportive activities. There are a lot of treatment options available for plantar fasciitis. We hypothesized that patients with chronic persistent plantar fasciitis can be successfully treated with radiofrequency nerve ablation (RFNA).Two hundred sixty-one patients with plantar fasciitis (378 feet) treated with RFNA from February 2017 to January 2019 were retrospectively assessed. All the patients had plantar heel pain for at least 6months. Based on their body mass index (BMI), the enrolled patients were divided into obese (BMI ≥ 30kg/m2) and non-obese (BMI < 30kg/m2) groups. The patients were asked to complete a questionnaire just before and after the procedure and during the final follow-up. The BNS Radiofrequency Lesion Generator was used during a single session. The patients' information, including their visual analogue scale (VAS) score and American Orthopaedic Foot and Ankle Society (AOFAS) score, was assessed. During their final follow-up, the patients were asked to rate the success of their treatment by choosing one of the following options: completely successful, very successful, moderately successful, marginally successful, or not successful.The VAS and AOFAS scores of all the patients were evaluated pre-procedure, in the first month after procedure, and during the final follow-up (8-24 months). There was a statistically significant difference between the pre-procedure and postprocedure VAS scores (P < .001), there was no statistically significant difference between the VAS scores in the first month postprocedure and during the final follow-up.There was a statistically significant difference between the pre-procedure and postprocedure AOFAS scores (P < .001), there was no statistically significant difference between the AOFAS scores in the first month postprocedure and during the final follow-up.RFNA can be used as an alternative method to surgical procedures for treating plantar fasciitis because it is safe and effective. The advantages of RFNA are that patients can quickly return to their work and resume weight-bearing activities.

Feasibility and safety of high-power ablation of atrial fibrillation with contact force-sensing catheter: The lesion size index-guided ablation.

Radiofrequency (RF) ablation is a commonly used method of atrial fibrillation (AF) treatment. High-power short-duration (HPSD) ablation has been suggested as a method to reduce procedure times whilst creating safe and lasting lesions. High-power ablation with contact force (CF)-sensing technology catheters might aid in a further improvement of safety whilst generating lasting transmural lesions. We report our experience using lesion size index (LSI)-guided 50 W ablation with a CF-sensing catheter of AF. We performed LSI-guided 50 W point-by-point ablation using a CF-sensing catheter (TactiCath). Target LSI at the anterior left atrium (LA) was 5.0 and at the posterior LA it was 4.5. Altogether, 4641 RF lesions were created in 86 consecutive patients. To reach a mean LSI of 4.9 ±0.01, a mean RF ablation time of 14.3 ±0.1 s was applied with a mean CF of 13.4 ±0.1 g. The RF time per lesion at the anterior wall of LA was 15.9 ±0.2 s, while it was 13 ±0.2 s at the posterior wall of LA. We observed force time integral (FTI) values between 36 g and 310 g. Procedure duration was 107 ±4 min with a RF ablation time of 15.4 ±0.6 min. No audible steam pops occurred. No pericardial effusion was observed. After a 1-year follow-up, no adverse events were reported and 83% of patients had no symptomatic arrhythmia recurrence. We provide evidence for the safety and efficacy of LSI-guided 50 W ablation using the TactiCath CF-sensing ablation catheter. These data support the use of high-power ablation with CF sensing technology to improve both safety and efficacy.

Idiopathic Ventricular Arrhythmias Originating from Different Portions of the Coronary Venous System: Prevalence, Electrocardiographic Characteristics, Catheter Ablation, and Complications.

(1) Background: To determine the prevalence, electrocardiographic characteristics, mapping, and ablation of IVAs arising from the CVS. (2) Methods: Detailed activation and pace mapping of the CVS IVAs was performed before attempted radiofrequency ablation (RFCA). (3) Results: The IVAs originating from the vicinity of the CVS represented approximately 5.27% (164/3113) of all IVAs; 94.51% (155/164) cases were accessed at the earliest identified site and 83.54% (137/164) IVAs were successfully ablated. The main coronary vein group had a relatively short procedure time, short fluoroscopy time, fewer radiofrequency lesions prior to success, and less Swartz sheath support. IVAs originating from the CVS had distinct ECG characteristics: Rs, RS or rS (with s or S) wave in lead V1 indicate the Vas arising from the proximal portion of the anterior interventricular vein (AIV) and summit-CV; Rs (with s or S) wave in leads V5–V6 indicate the Vas arising from the adjacent regions of the distal great cardiac vein 1 (DGCV1); positive wave (R, Rs or r) In lead I indicate the VAs ori”inat’ng from Summit-CV and posterior wall subgroup (including middle cardiac vein [MCV], posterior lateral vein [PLV], coronary sinus [CS]). Compared with the IVAs originating from the endocardial mitral annulus, a PdW > 45 ms, an IDT > 74 ms, and an MDI > 0.50 indicate a CVS origin of the IVAs. The common peri-procedure complications were CV dissection (6.45%, 10/155), CV rupture (1.29%, 2/155), coronary artery spasm (1.29%, 2/155), coronary artery stenosis (0.65%, 1/155), pericardial effusion (0.65%, 1/155) and tamponade (1.29%, 2/155). Stenosis of coronary arteries was not observed at the adjacent ablation site in the CVS during follow-up. (4) Conclusions: vAs arising from the CVS are not a rare phenomenon. Several ECG and procedure characteristics could help regionalize, map, and ablate the origin of IVAs from different portions of the CVS. RFCA within the CVS was relatively effective and safe.

Morphology of the trigeminal ganglion: anatomical structures related to trigeminal radiofrequency rhizotomy.

Trigeminal neuralgia is the most common example of craniofacial neuralgia. Its etiology is unknown and is characterized by severe episodes of paroxysmal pain. The trigeminal ganglion and its adjacent anatomical structures have a complex anatomy. The foramen ovale is of great importance during surgical procedures such as percutaneous trigeminal rhizotomy for trigeminal neuralgia. We aimed to identify the anatomical structures associated with the trigeminal ganglion and radiofrequency rhizotomy on cadavers and investigate their relationship with the electrodes used during rhizotomy to determine the contribution of the electrode diameter and length to the effectiveness of the lesion formation on the ganglion. Five fresh-frozen cadaver heads injected with red silicone/latex were used. A percutaneous puncture was made by inserting of a cannula through the foramen ovale to create a pathway for electrodes. The relationships between the electrodes, Meckel's cave, trigeminal ganglion, and neurovascular structures were observed and morphometric measurements were obtained using a digital caliper. Trigeminal ganglion, therefore the electrode in its final position, shows proximity with important anatomical structures. The electrode was inserted posteriorly into the foramen ovale in all of the specimens and was located on the retrogasserian fibers. This study revealed that the electrodes targeting the ganglion and passing through the foramen ovale may cause a radiofrequency lesion due to the contact effect of the dura itself pressing on the electrode. Pushing the cannula beyond the petroclival angle may result in puncturing of the dura propria and moving further away from the target area. The success of radiofrequency rhizotomy is directly related to the area affected by the lesion. Understanding the mechanism of action underlying this procedure will ensure the effectiveness, success, and sustainability of the treatment.

Spatial temperature reconstructions in myocardial tissues undergoing radiofrequency ablations by performing high-resolved temperature measurements.

Radiofrequency (RF) lesion creation is related to the heat propagation induced by RF application on tissues. Thermocouple embedded in the RF antenna are not able to predict deep tissue temperature at various level. This study aims to investigate the influence of power delivered on radiofrequency catheter ablation (RFCA) effects by means of high resolved 2D temperature maps. Three trials of four ablations (12 applications) were executed on each specimen of healthy excised swine myocardium in different application points at four RF power values (30W, 40W, 50W, and 60W) for a fixed treatment time. All the data provided by the fiber Bragg gratings (FBGs) were analyzed. Temperature variations (ΔT) in time recorded in the 28 sites of measurements were reported. Also, temperature maps showing the ΔT spatial distribution reached within the tissue at the end of the RFCA were produced and displayed, together with the representation of the lethal isotherm. Moreover, the time of achievement of the lethal isotherm at different tissue depths (from 1 to 8mm) was evaluated for the four power settings. Temperature trends reported comparable profiles across the different power settings. ΔT values and ΔT rising times showed dependence on the sensors' proximity to the RF energy source and on the set RF power. Temperature maps confirmed that heat propagation occurs preferentially along the width of the tissue than in the depth. Also, for the adjusted treatment time, no power setting guarantees lesions thicker than 6mm. ΔT maximal values and ΔT rising time strongly depends on the proximity of the tissues to RF energy source, as well as on the RF power setting. A plateau is reached in lesion size, regardless of the power setting. A first correlation between lesion size, power setting, and time to achieve lethal isotherms has been established.

Anatomical study and clinical significance of rami communicantes of the lumbar spine

Background and objectivesRami communicantes (RC) infiltration and radiofrequency lesions are new techniques for the treatment of discogenic low back pain (DLBP). Their efficacy is controversial, and the classification of RC...

Comparison of ablation index versus time-guided radiofrequency energy dosing using normal and half-normal saline irrigation in a porcine left ventricular model.

Ablation Index (AI) is a multiparametric quality marker to assess the durability of radiofrequency (RF) lesions. The comparative effectiveness and safety of AI versus time-based energy dosing for ablation of ventricular arrhythmias are unknown. We compared AI and time-based RF dosing strategies in the left ventricles (LVs) of freshly harvested porcine hearts. Ablation was performed in vitro with an open-irrigated ablation catheter (Thermocool ST/SF), 40 W, contact force 10-15 g. Tissue samples were stained in triphenyltetrazolium chloride for the measurement of lesion dimensions. A total of 560 lesions were performed (AI-group: [n = 360]; time-group: [n = 200]). Using normal saline (NS) (n = 280), growth in lesion depth slowed after 30 s and AI > 550 in comparison to width, volume, and magnitude of impedance drops which continued to increase with longer RF duration. Risk of steam pop (SP) was higher for RF > 30 s (RF < 30 s:1 SP [2.5%] vs. RF > 30 s: 15 SP [25%];p = .002) or AI targets >550 (AI: 350-550: 2 SP [2%] vs. AI 600-750: 15 SP [19%];p = .001). Using half-normal saline (HNS) (n = 280), lesion dimension and impedance drops were larger and growth in lesion depth slowed earlier (AI: 500). Risk of SPs was higher above AI 550 (AI: 350-550: 7 [7%] SPs vs. AI 600-750: 28 [35%] SPs; p < .00001). While codependent variables, correlation between AI and time was modest-to-strong but decreased with longer RF duration. In this ex vivo study, AI was a better predictor of lesion dimensions than ablation time and magnitude of impedance drop in the LV using NS and HNS irrigation. AI targets above 550 led to a higher risk of SPs. Future trials are required to verify these findings.

Impact of catheter contact angle on lesion formation and durability of pulmonary vein isolation

PurposeThis study is aimed to evaluate the impact of catheter contact angle on lesion formation and durability of pulmonary vein isolation (PVI).MethodsBoth in vitro experiment and retrospective observational study were conducted. For in vitro experiment, radiofrequency lesions were created on explanted swine hearts in three different catheter contact angles (0°, 45°, and 90°). In the retrospective observational study, we assessed patients who had undergone repeat catheter ablation due to atrial fibrillation recurrence after initial PVI. When pulmonary vein (PV) reconnection was observed, we analyzed the previous ablation points within and without the gap area. The gap areas were where ablation had changed the PV activation sequence or eliminated the PV potential in the repeat session.ResultsIn the in vitro experiment, lesion width was the smallest (5.3 ± 0.4 mm) in perpendicular contact compared to 0° (vs 5.8 ± 0.5 mm, p = 0.040) and 45° (vs 6.4 ± 0.4 mm, p < 0.001). In the retrospective observational study, we assessed 666 tags of 16 patients with PV reconnections, and 60 tags were in the gap area. Tags in the gap area had longer interlesion distance (odds ratio [OR] 1.49, p < 0.001), greater contact force variability (OR 1.03, p = 0.008), and higher rate of perpendicular contact (OR 3.26, p < 0.001) on multivariate analysis.ConclusionsPerpendicular contact was associated with a smaller lesion and higher rate of PV reconnection.

Combined Unilateral Radiofrequency Lesioning of the Motor Thalamus, Field of Forel, and Zona Incerta: A Series of Cases With Dystonia.

Dystonia is a group of disorders characterized by involuntary slow repetitive twisting movements and/or abnormal posture. Surgical options such as neuromodulation through deep brain stimulation and neuroablative procedures are available for patients who do not respond to conservative treatment. To present our series of patients with dystonia who were treated with stereotactic combined unilateral radiofrequency lesioning of the motor thalamus, field of Forel, and zona incerta. Medical records of 50 patients with dystonia who were treated with unilateral combined lesions were reviewed. Outcomes of the surgical procedure were evaluated using the Burke-Fahn-Marsden Dystonia Rating Scale (with movement and disability subscales) and Unified Parkinson's Disease Rating Scale-tremor items. Based on the symptoms, patients were categorized as having generalized dystonia (34%), hemidystonia (30%), and dystonic tremor (DT) (36%). Primary/idiopathic dystonia, primary genetic/hereditary dystonia, and secondary dystonia accounted for 16%, 4%, and 80% of patients, respectively. The mean follow-up duration was 156.2 ± 88.9 mo. The overall improvement in the Burke-Fahn-Marsden Dystonia Rating Scale scores (movement and disability, respectively) was 57.8% and 36.4% in generalized dystonia, 60.0% and 45.8% in hemidystonia, and 65.6% and 56.8% in DT. Patients with DT showed an 83.3% improvement in mean Unified Parkinson's Disease Rating Scale tremor score. Patients with cerebral palsy showed mean improvements of 66.7% in movement scores and 50.8% in disability scores. No mortality or major morbidity was observed postoperatively. Stereotactic radiofrequency unilateral combined thalamotomy, campotomy, and zona incerta lesions may be an effective surgical alternative for patients with dystonia, especially those with secondary dystonia resistant to deep brain stimulation.