Epicardial Atrial Ablation Using a Novel Articulated Robotic Medical Probe Via a Percutaneous Subxiphoid Approach

OBJECTIVE: Minimally invasive epicardial atrial ablation to cure atrial fibrillation through the use of a percutaneous subxiphoid approach currently has a lack of dedicated technology for intrapericardial navigation around the beating heart. We have developed a novel articulated robotic medical probe and performed preliminary experiments in a porcine preparation. METHODS: In five large, healthy pigs, the teleoperated robotic system was introduced inside the pericardial space through a percutaneous subxiphoid approach. Secondary visualization of the left atrium and left atrial appendage was achieved with the use of a 5-mm scope inserted through a left thoracic port. The operator actively controlled the path of the robot by using a master manipulator. The catheter, with an irrigated radiofrequency tip, was guided through the working port of the robot to achieve epicardial ablation of the left atrium. RESULTS: Access to the pericardial space and progression around the left atrium was successful in all cases, with no interference with the beating heart such as a fatal arrhythmia, unexpected bleeding, and hypotension. Epicardial ablation was successfully performed in all five cases. No adverse hemodynamic or electrophysiological events were noted during the trials. When the animals were killed, there was no visually detected injury on the surrounding mediastinal structures caused by ablation. Transmural ablation was confirmed by histopathology of the left atrium. CONCLUSIONS: We have developed a dedicated articulated robotic medical probe and successfully performed epicardial left atrial radiofrequency ablation. Based on the feedback from these preliminary experiments, the radius of curvature and proper visualization of the device are being improved in the next generation prototype.     

Ablation of Myocardial Tissue With Nanosecond Pulsed Electric Fields

Background

Ablation of cardiac tissue is an essential tool for the treatment of arrhythmias, particularly of atrial fibrillation, atrial flutter, and ventricular tachycardia. Current ablation technologies suffer from substantial recurrence rates, thermal side effects, and long procedure times. We demonstrate that ablation with nanosecond pulsed electric fields (nsPEFs) can potentially overcome these limitations.

Methods

We used optical mapping to monitor electrical activity in Langendorff-perfused New Zealand rabbit hearts (n = 12). We repeatedly inserted two shock electrodes, spaced 2–4 mm apart, into the ventricles (through the entire wall) and applied nanosecond pulsed electric fields (nsPEF) (5–20 kV/cm, 350 ns duration, at varying pulse numbers and frequencies) to create linear lesions of 12–18 mm length. Hearts were stained either with tetrazolium chloride (TTC) or propidium iodide (PI) to determine the extent of ablation. Some stained lesions were sectioned to obtain the three-dimensional geometry of the ablated volume.

Results

In all animals (12/12), we were able to create nonconducting lesions with less than 2 seconds of nsPEF application per site and minimal heating (< 0.2°C) of the tissue. The geometry of the ablated volume was smoother and more uniform throughout the wall than typical for RF ablation. The width of the lesions could be controlled up to 6 mm via the electrode spacing and the shock parameters.

Conclusions

Ablation with nsPEFs is a promising alternative to radiofrequency (RF) ablation of AF. It may dramatically reduce procedure times and produce more consistent lesion thickness than RF ablation.     

Effective contact and outcome after pulmonary vein isolation in novel circular multi-electrode atrial fibrillation ablation

Introduction

Pulmonary vein (PV) reconnection is frequently the cause of recurrence of atrial fibrillation (AF) after ablation. The second-generation gold multi-electrode ablation (Gold-MEA) catheter has a new design possibly resulting in improved lesion formation compared with its predecessor. We aimed to determine the association between effective radiofrequency applications with the Gold-MEA catheter and outcome after AF ablation.

Methods

50 consecutive patients with paroxysmal AF underwent Gold-MEA (PVAC GOLD^TM, Medtronic Inc.) ablation. The Gold-MEA catheter was navigated to the PV ostium by fluoroscopy. Duty-cycled radiofrequency ablations were performed at all PV ostia. Lesions were considered transmural when electrode temperature was >50 °C and power >3 W for >30 seconds. After the ablation procedure, patients visited the outpatient clinic at 3?month intervals including 24-hour Holter ECGs.

Results

Mean age was 56 years. All PVs were acutely isolated with the Gold-MEA catheter. Procedure time was 111 ± 22 minutes, ablation time was 24 ± 6.7 minutes and fluoroscopy time was 20 ± 8.1 minutes. No procedure-related complications were observed. One year after ablation, 60?% of patients were still free of arrhythmia recurrences after a single PV isolation attempt. The number of transmural lesions was associated with arrhythmia-free survival: 25.0?% in <72 transmural lesions, 64.3?% in 72–108 transmural lesions and 71.4?% in >108 transmural lesions (p = 0.029).

Conclusion

PV isolation can be performed successfully with the Gold-MEA catheter, with a favourable safety profile. Transmurality of lesions was associated with ablation success and may improve AF ablation success.

     

An in vivo comparison of radiofrequency cardiac lesions formed by standard and magnetically steered 4 mm tip catheters

Background. In vivo comparison of cardiac radiofrequency ablation lesions between standard and magnetically steered 4 mm tip catheters has never been reported. Methods. High and low right atrium (RA) free wall, isthmus, right ventricle (RV) free wall and outflow tract lesions were studied macroscopically and microscopically five days after lesion formation in seven pigs. Shape, size, thrombus formation, and ablation parameters were compared. The effect of minimal, medium and high wall contact was assessed by a contact measurement utility for magnetic catheters. Results. All 14 RA free wall lesions were transmural with a similar epicardial and endocardial surface area. In the RV, the epicardial area usually appeared to be smaller than the endocardial area with standard catheters. Isthmus lesions were difficult to assess transmurality. There was no difference in endocardial area: standard 39 mm² (range 16 to 82 mm²) vs. magnetic 36 mm² (range 23 to 111 mm²). If the catheter tip was perpendicular to the tissue, magnetic lesions were more often round or oval, while standard lesions were more often elongated (p<0.05). When the catheter tip was parallel to tissue, lesions always tended to be elongated. Microscopic characteristics were similar. The contact utility was not useful. Average impedance (p<0.0001) and energy delivered (p<0.05) were less with magnetic catheters. Conclusion. Lesions from magnetically steered catheters are transmural of similar size, but with less variability than standard catheter lesions when the tip is perpendicular to the tissue. Magnetic lesions are associated with lower impedance and energy delivery. This suggests a more stable tip-to-tissue contact. (Neth Heart J 2010;18:66–71.)     

Robotic Ablation of Atrial Fibrillation

Background: Pulmonary vein isolation (PVI) is an established treatment for atrial fibrillation (AF). During PVI an electrical conduction block between pulmonary vein (PV) and left atrium (LA) is created. This conduction block prevents AF, which is triggered by irregular electric activity originating from the PV. However, transmural atrial lesions are required which can be challenging. Re-conduction and AF recurrence occur in 20 - 40% of the cases. Robotic catheter systems aim to improve catheter steerability. Here, a procedure with a new remote catheter system (RCS), is presented. Objective of this article is to show feasibility of robotic AF ablation with a novel system. Materials and Methods: After interatrial trans-septal puncture is performed using a long sheath and needle under fluoroscopic guidance. The needle is removed and a guide wire is placed in the left superior PV. Then an ablation catheter is positioned in the LA, using the sheath and wire as guide to the LA. LA angiography is performed over the sheath. A circular mapping catheter is positioned via the long sheath into the LA and a three-dimensional (3-D) anatomical reconstruction of the LA is performed. The handle of the ablation catheter is positioned in the robotic arm of the Amigo system and the ablation procedure begins. During the ablation procedure, the operator manipulates the ablation catheter via the robotic arm with the use of a remote control. The ablation is performed by creating point-by-point lesions around the left and right PV ostia. Contact force is measured at the catheter tip to provide feedback of catheter-tissue contact. Conduction block is confirmed by recording the PV potentials on the circular mapping catheter and by pacing maneuvers. The operator stays out of the radiationfield during ablation. Conclusion: The novel catheter system allows ablation with high stability on low operator fluoroscopy exposure.     

双极射频消融改良迷宫术治疗房颤的中远期疗效及其影响因素分析

目的:分析心脏瓣膜置换同期行双极射频消融改良迷宫术治疗房颤的术后中远期疗效及其影响因素。方法:选取2007年7月至2010年12月于我院行心脏瓣膜置换同期行双极射频消融改良迷宫术治疗房颤的72例患者,术后随访3至6年,获得患者术后十二导联心电图、24 h动态心电图和心脏彩超结果,并且记录术后药物应用、相关并发症、心功能恢复情况及生活质量是否改善等情况。根据心电图结果,将患者分为窦性心律组与非窦性心律组,应用统计学方法比较两组患者术前相关因素是否有差异。结果:截止至随访终点,有效随访的68例患者中窦性心律维持率为63.2%。单因素分析显示术前房颤病程、术前左室射血分数、是否合并三尖瓣成形或置换是影响手术效果的影响因素,多因素分析显示术前房颤病程、合并三尖瓣成形或置换是影响手术效果的危险因素。结论:心脏瓣膜置换同期行双极射频消融改良迷宫术治疗房颤的中晚期疗效好,术后并发症少,能够有效防止血栓栓塞,术前房颤病程长、合并三尖瓣成形或置换的患者术后中远期效果相对较差。     

Insights into the pathogenesis of vein graft disease: lessons from intravascular ultrasound

Background

Myocardial contrast echocardiography (MCE) allows visualization of radiofrequency (RF) ablation lesions in the left ventricle in an animal model. Aim: To test whether MCE allows visualization of RF and cryo ablation lesions in the human right atrium using three-dimensional echocardiography.

Methods

18 patients underwent catheter ablation of a supraventricular tachycardia and were included in this prospective single-blind study. Twelve patients were ablated inside Koch's triangle and 6, who served as controls, outside this area. Three-dimensional echocardiography of Koch's triangle was performed before and after the ablation procedure in all patients, using respiration and ECG gated pullback of a 9 MHz ICE transducer, with and without continuous intravenous echocontrast infusion (SonoVue, Bracco). Two independent observers analyzed the data off-line.

Results

MCE identified ablation lesions as a low contrast area within the normal atrial myocardial tissue. Craters on the endocardial surface were seen in 10 (83%) patients after ablation. Lesions were identified in 11 out of 12 patients (92%). None of the control patients were recognized as having been ablated. The confidence score of the independent echo reviewer tended to be higher when the number of applications increased.

Conclusions

1. MCE allows direct visualization of ablation lesions in the human atrial myocardium. 2. Both RF and cryo energy lesions can be identified using MCE.     

Finite Element Analysis of Hepatic Radiofrequency Ablation Probes using Temperature-Dependent Electrical Conductivity

Background

Few finite element models (FEM) have been developed to describe the electric field, specific absorption rate (SAR), and the temperature distribution surrounding hepatic radiofrequency ablation probes. To date, a coupled finite element model that accounts for the temperature-dependent electrical conductivity changes has not been developed for ablation type devices. While it is widely acknowledged that accounting for temperature dependent phenomena may affect the outcome of these models, the effect has not been assessed.

Methods

The results of four finite element models are compared: constant electrical conductivity without tissue perfusion, temperature-dependent conductivity without tissue perfusion, constant electrical conductivity with tissue perfusion, and temperature-dependent conductivity with tissue perfusion.

Results

The data demonstrate that significant errors are generated when constant electrical conductivity is assumed in coupled electrical-heat transfer problems that operate at high temperatures. These errors appear to be closely related to the temperature at which the ablation device operates and not to the amount of power applied by the device or the state of tissue perfusion.

Conclusion

Accounting for temperature-dependent phenomena may be critically important in the safe operation of radiofrequency ablation device that operate near 100°C.

     

超声引导经皮微波消融治疗邻近血管的原发性肝癌的疗效分析

探讨超声引导经皮微波消融治疗邻近血管的原发性肝癌的疗效。2010年1月至2013年6月期间,回顾性分析在我院采用超声引导下微波消融技术治疗的213例(267个病灶)原发性肝癌患者的病例资料,根据患者病灶位置分为邻近血管组(76例,91个病灶)和对照组(137例,176个病灶),比较两组患者的微波消融次数、微波消融时间、完全消融率、局部肿瘤进展率、累计存活率及并发症。邻近血管组和对照组的原发性肝癌患者消融次数均为1~3次,两组平均微波消融次数无显著差异(p<0.05)。两组微波消融时间为5~28 min,其中邻近血管组显著高于对照组(p>0.05)。微波消融1个月后,邻近血管组的完全消融率与对照组无显著差异(p<0.05)。两组患者在3个阶段(1随访1年,3年和5年)的的局部肿瘤进展率和累计生存率无统计学差异(p<0.05)。两组患者5年随访时间内分别有29例和53例患者死亡。主要死亡原因包括肝癌进展、肝功能衰竭、血管曲张破裂、脑出血、急性肺栓塞、心肌梗死等。邻近血管组共有25例出现术后并发症,对照组有44例。主要并发症类型为腹腔积液、膈疝、出血、肝脓肿、气胸、肝区疼痛和发热。两组之间并发症发生率无统计学意义(p=0.907)。微波消融治疗邻近血管的原发性肝癌具有较好的局部肿瘤控制率,可对邻近血管的危险病灶区域进行有效治疗。     

Anatomic Twist to a Straightforward Ablation

Atrioventricular (AV) junction ablation for treatment of refractory atrial fibrillation is a well defined, standardized procedure and the simplest of commonly performed radiofrequency ablations in the field of cardiac electrophysiology. We report successful AV junction ablation using an inferior approach in a case of inferior vena cava interruption. Inability during the procedure to initially pass the ablation catheter into the right ventricle, combined with low amplitude electrograms, led to suspicion of an anatomic abnormality. This was determined to be a heterotaxy syndrome with inferior vena cava interruption and azygos continuation, draining in turn into the superior vena cava. Advancing Schwartz right 0 (SRO) sheath through the venous abnormality into the right atrium allowed adequate catheter stability to successfully induce complete AV block with radiofrequency energy.     

Anatomical Characteristics of Pulmonary Veins for the Prediction of Postoperative Recurrence after Radiofrequency Catheter Ablation of Atrial Fibrillation

Background

The relationship between focal pulmonary vein potential and atrial fibrillation (AF) has been confirmed. Pulmonary vein (PV) isolation and circumferential pulmonary vein ablation have been the most commonly used procedures of radiofrequency ablation. However, few studies have investigated the relationship between anatomical characteristics of PV and AF recurrences after radiofrequency ablation.

Methodology

For 267 AF patients treated by radiofrequency catheter ablation, the anatomic structure characteristics of pulmonary veins were assessed by multi-slice spiral computed tomography while the values of left atrial diameter (LAD) were measured with transesophageal ultrasonic cardiogram. After radiofrequency catheter ablation, postoperative recurrence was evaluated during a 10-month term follow-up.

Principal Findings

During follow-up, postoperative recurrence occurred in 44 patients. The mean diameters of LAD, left superior PV, right superior PV, all left PV, and all superior PV were significantly larger in patients with postoperative recurrence (Recurrence vs. Non-recurrence group; 43.9 ± 6.4 mm vs. 40.7 ± 5.6 mm; 18.4 ± 2.1 mm vs. 17.1 ± 3.1 mm; 18.2 ± 2.8 mm vs. 17.2 mm ± 3.9 mm; 16.4 ± 1.5 mm vs. 15.6 ± 2.5 mm; 18.3 ± 2.1 mm vs. 17.1 ± 3.0 mm; respectively; all P < 0.05). Multivariable survival analysis showed that the type and the course of AF, LAD, and the diameters of all superior PV were the independent risk factors for the postoperative recurrence after radiofrequency catheter ablation.

Conclusions

The enlargements of all superior PV and LAD, long course of diseases, and persistent AF were the independent risk factors for the postoperative recurrence after radiofrequency catheter ablation.     

Assessment of the Correlation Between Two Defining Criteria for Bidirectional Isthmic Block in the Ablation of Typical Atrial Flutter

Background

A complete, bidirectional conduction block in the cavotricuspid isthmus (CTI) represents the end-point of the typical atrial flutter ablation. We investigated the correlation between two criteria for successful ablation, one based on the atrial bipolar electrogram morphology before and after complete CTI conduction block, compared to the standard criteria of differential pacing and reversal in the right atrial depolarization sequence during coronary sinus (CS) pacing.

Method

We conducted a retrospective study in 111 patients (81 males, average age 62±10 years) who underwent an atrial flutter ablation during September 2007 - July 2009 in the Cardiology - Rehabilitation Hospital, UMF Cluj-Napoca. We assessed the presence of a bidirectional block at the end of the procedure using the standard criteria. We then analyzed the morphology of the bipolar atrial electrograms adjacent to the ablation line, before and after CTI conduction block.

Results

A change from a qRs morphology to a rSr'' morphology when pacing from the coronary sinus and from a rsr'' morphology to a QRS morphology when pacing from the low-lateral right atrium was associated with a CTI conduction block. Sensitivity (Se), specificity(Sp), positive predictive value (PPV), negative predictive value (NPV) were 96%, 89%, 99% and 67% respectively.

Conclusion

Our study suggests that the analysis of the atrial bipolar electrogram next to the ablation line before and after CTI ablation may be used as a reliable criterion to validate CTI conduction block due to its high sensitivity, specificity and positive predictive value.     

Determination of lesion size by ultrasound during radiofrequency catheter ablation.

The catheter tip temperature that is used to control the radiofrequency generator output poorly correlates to lesion size. We, therefore, evaluated lesions created in vitro using a B-mode ultrasound imaging device as a potential means to assess lesion generation during RF applications non-invasively. Porcine ventricular tissue was immersed in saline solution at 37 degrees C. The catheter was fixed in a holder and positioned in a parallel orientation to the tissue with an array transducer (7.5 MHz) app. 3 cm above the tissue. Lesions were produced either in a temperature controlled mode with a 4-mm tip catheter with different target temperatures (50, 60, 70 and 80 degrees C, 80 W maximum output) or in a power controlled mode (25, 50 and 75 W, 20 ml/min irrigation flow) using an irrigated tip catheter. Different contact forces (0.5 N, 1.0 N) were tested, and RF was delivered for 60 s. A total of 138 lesions was produced. Out of these, 128 could be identified on the ultrasound image. The lesion depth and volume was on average 4.1 +/- 1.6 mm and 52 +/- 53 mm3 as determined by ultrasound and 3.9 +/- 1.7 mm and 52 +/- 55 mm3 as measured thereafter, respectively. A linear correlation between the lesion size determined by ultrasound and that measured thereafter was demonstrated with a correlation coefficient of r = 0.87 for lesion depth and r = 0.93 for lesion volume. We conclude that lesions can be assessed by B-mode ultrasound imaging.     

Comparison of Ablation Zones among Different Tissues Using 2450-MHz Cooled-Shaft Microwave Antenna: Results in Ex Vivo Porcine Models

Background

For complete tumor ablation in different tissues, it is necessary to investigate the exact coagulation zone of microwave ablation in different tissues. The aim of this study was to compare the extent of microwave ablation zone in muscle, liver and adipose tissue in ex vivo porcine models and assess the shape of microwave coagulation zone among these tissues.

Materials and Methods

Microwave ablations were performed in ex vivo porcine muscle, liver and adipose tissue using 2450-MHz cooled-shaft microwave antenna. The content of water, fat and protein in these three tissues was determined. Two power increments (40 and 80 W) and five time increments (1, 3, 5, 7, and 10 minutes) were used in this study. Diameters and shapes of the ablation zones were assessed on gross specimens.

Results

The average percentages of water, fat and protein in these three tissues were significantly different (P < 0.001), respectively. The long-axis and short-axis diameters among these three tissues at each time-power combination were not significantly different (P > 0.05). The coagulation zones were all elliptical in muscle, liver and adipose tissue. When microwave ablation was performed in the tissue containing both muscle and adipose tissue, the coagulation zone was also elliptical. Regardless of the output power, the ellipticity index (EI) value of 1 minute treatment duration was higher than that of 10 minutes treatment duration (P < 0.05). Furthermore, the EI value did not decrease significantly when the treatment duration was more than 5 minutes (P > 0.05).

Conclusion

The extent of microwave ablation zones was not significantly different among completely different tissues. Microwave ablations with ≥ 5 minutes time duration can induce coagulation zones with clinical desirable shape. Future clinical studies are still required to determine the role of microwave ablation in different tissues.     

Tissue temperature feedback control of power: the key to successful ablation

Multiple ablation technologies are used to treat atrial fibrillation during cardiac operations. All such ablation technologies use locally induced temperature extremes (>50°C or <-20°C) to kill tissue and create a lesion pattern in the atria which blocks activation pathways that initiate and sustain atrial fibrillation. The technologies used to heat tissue have included radiofrequency (RF), microwave, high-intensity focused ultrasound, and infrared laser. RF accounts for more than 95% of the heating-based ablation technology used by cardiac surgeons. Energy delivery with RF is easier to control than with some other technologies, the heating produced by the energy source is well understood, and manufacturing costs are not excessive. Whichever heating technology is used, control of energy delivery is required to ensure both safe and effective heating of the targeted tissue. All targeted tissue needs to be heated above 50°C to achieve cell death. However, the targeted tissue should not be heated above 100°C, as this can cause perforation due to a steam pop. In addition, adjacent noncardiac tissues must not be damaged during the ablation procedure. The best method to achieve this control uses direct measurement of tissue temperature, because the tissue temperature defines both the safe and effective limits for the ablative process.     

Transmural Ultrasound Imaging of Thermal Lesion and Action Potential Changes in Perfused Canine Cardiac Wedge Preparations by High Intensity Focused Ultrasound Ablation

Intra-procedural imaging is important for guiding cardiac arrhythmia ablation. It is difficult to obtain intra-procedural correlation of thermal lesion formation with action potential (AP) changes in the transmural plane during ablation. This study tested parametric ultrasound imaging for transmural imaging of lesion and AP changes in high intensity focused ultrasound (HIFU) ablation using coronary perfused canine ventricular wedge preparations (n = 13). The preparations were paced from epi/endocardial surfaces and subjected to HIFU application (3.5 MHz, 11 Hz pulse-repetition-frequency, 70% duty cycle, duration 4 s, 3500 W/cm²), during which simultaneous optical mapping (1 kframes/s) using di-4-ANEPPS and ultrasound imaging (30 MHz) of the same transmural surface of the wedge were performed. Spatiotemporally correlated AP measurements and ultrasound imaging allowed quantification of the reduction of AP amplitude (APA), shortening of AP duration at 50% repolarization, AP triangulation, decrease of optical AP rise, and change of conduction velocity along tissue depth direction within and surrounding HIFU lesions. The threshold of irreversible change in APA correlating to lesions was determined to be 43±1% with a receiver operating characteristic (ROC) area under curve (AUC) of 0.96±0.01 (n = 13). Ultrasound imaging parameters such as integrated backscatter, Rayleigh (α) and log-normal (σ) parameters, cumulative extrema of σ were tested, with the cumulative extrema of σ performing the best in detecting lesion (ROC AUC 0.89±0.01, n = 13) and change of APA (ROC AUC 0.79±0.03, n = 13). In conclusion, characteristic tissue and AP changes in HIFU ablation were identified and spatiotemporally correlated using optical mapping and ultrasound imaging. Parametric ultrasound imaging using cumulative extrema of σ can detect HIFU lesion and APA reduction.     

Atrial sensor,remote monitoring and new anticoagulant drugs: Identification and treatment of a patient with unknown and asymptomatic atrial flutter

This case report describes how new tools and technologies can drive a different approach in the management of arrhythmic patients. An unknown and asymptomatic atrial flutter was detected by the atrial sensor mounted in a single lead implantable cardioverter defibrillator. Moreover daily remote monitoring of the device allowed early notification and prompt clinical reaction. Anticoagulant therapy onset, radiofrequency ablation and the following anticoagulant therapy removal were driven by the device data transmissions.     

射频消融改善阵发性和长期持续性心房颤动患者生活质量的研究

目的:比较射频消融对阵发性和长期持续性心房颤动(房颤)患者生活质量的改善。方法:纳入2011年5月至2016年8月接受射频消融治疗的阵发性房颤患者142例和长期持续性房颤61例。消融前和消融后12个月采用健康状况调查简表(SF-36)评估患者生活质量。结果:长期持续性房颤患者年龄及合并高血压和慢性心功能不全的比例高于阵发性房颤组。消融后12个月,两组患者心理健康(MCS)和生理健康(PCS)评分均显著提高(P0.01)。长期持续性房颤患者MCS和PCS的改善幅度显著高于阵发性房颤组(P0.01)。房颤未复发患者生活质量的提高幅度显著高于复发患者(P0.01)。结论:射频消融改善长期持续性房颤患者生活质量的幅度高于阵发性房颤,房颤复发将影响患者的生活质量。     

Successful Ablation of Cavotricuspid Isthmus-dependent Atrial Flutter Guided by Contact Force Vector in a Patient After a Tricuspid Valve Replacement

A 46-year-old man after a tricuspid valve replacement due to traumatic severe tricuspid regurgitation developed cavotricuspid isthmus-dependent counterclockwise atrial flutter. During a linear ablation using a contact force-sensing irrigated ablation catheter, the flutter could be terminated by a radiofrequency application within a deep pouch just below the bioprosthetic tricuspid valve.     

Experimental morphological evaluation of the effectiveness of bipolar radiofrequency ablation for thyroid nodules

Over the recent decade, the method of radiofrequency ablation has been increasingly used for treatment of thyroid nodules. However, there is clear need for additional morphological experimental works on evaluating the effectiveness of application of different devices. This work presents results of investigation of an original device operating on the principle of bipolar radiofrequency ablation, and its high effectiveness in eliminating thyroid nodules with different consistencies and malignancy potentials has been proven, which offers broad prospects for introducing the patented radiofrequency-ablation applicator into practice, alongside other methods of minimally invasive surgery.