Comparison of lesion sizes produced by cryoablation and open irrigation radiofrequency ablation catheters

Introduction: The relative lesion sizes created by large electrode cryoablation catheter and irrigated radiofrequency (RF) ablation are not known. The purpose of this study was to directly compare lesion sizes created by cryoablation and irrigated RF under controlled conditions.
Methods and Results : Ablation lesions were created in freshly harvested porcine left ventricular myocardium in a blood-filled tissue bath using an 8-mm-tip cryoablation catheter and a 3.5-mm-tip open-irrigated RF ablation catheter. Lesions were created under all permutations of the following conditions: electrode orientation vertical (perpendicular) or horizontal (parallel) to the tissue, electrode contact pressure at 6 or 20 g, and blood flow at 0.2 or 0.4 m/s over the electrode-tissue interface. The largest lesion volumes created with cryoablation were 961 ± 103 mm³, compared with the largest lesions volumes created with RF of 680 ± 48 mm³ (P < 0.001). The 3-way interactions among electrode orientation, contact pressure, and superfusate blood velocity accounted for the variation in lesion volumes for both catheters (both r²= 0.97, both P < 0.0001). The greater contact pressure increased lesion size for both cryoablation and RF. For cryoablation, lesion sizes were increased by the horizontal orientation and by the lower blood flow velocity. For open-irrigated RF, lesion sizes were significantly reduced by the horizontal orientation, however.
Conclusions : Depending on conditions of electrode orientation, contact pressure, and blood velocity, either 8-mm-tip cryoablation or open-irrigated RF may produce the larger lesion volumes. Open-irrigated RF lesion sizes are reduced in the horizontal catheter orientation.     

顽固性室性早搏的导管标测与射频消融治疗

采用射频导管消融术对症状明显、药物无效的１０例顽固性室性早搏（简称室早）进行治疗。将消融电极送至右室流出道区域，以Ｓ１Ｓ１或ＲＳ２早搏刺激标测到与体表１２导联心电图记录的自发室早ＱＲＳ波群图形完全相同，并且激动标测时自发室早的局部电图较体表心电图ＱＲＳ波群提前３０ｍｓ以上的部位为消融靶点。以室早在放电后１０ｓ内消失，维持稳定窦性心律３０～６０ｍｉｎ为即刻成功标准。９例患者经１０～２０Ｗ、消融６０～１８０ｓ，早搏和短阵室速完全消失；１例失败。平均随访１１个月，未服任何抗心律失常药物症状消失，复查心电图和动态心电图，９例中８例无早搏、１例为偶发室早，均无并发症。提示射频导管消融术是治疗某些右室流出道早搏的可行方法。     

T cell-mediated immunity in murine malaria. II. Induction of protective immunity to P. chabaudi by antigen fed macrophages and antigen educated lymphocytes

We previously described assay systems for generating antigen specific proliferating T cells to P. chabaudi antigens. In the present study we examine whether the various sensitization approaches confer immunity against a cloned virulent strain IP-PCI of P. chabaudi. We present data indicating that effective specific protective immunity can be induced through P. chabaudi antigen fed macrophages and antigen educated spleen cells (initiator lymphocytes). The expression of this protective immunity is proposed to depend on (a) antigen presentation and/or accessory function of macrophages and (b) the subsequent activation of T cell functions related to protection. Indeed analysis of different macrophage populations revealed a correlation between the expression of Ia molecules and IL-1 secretion with their capacity to induce antigen specific T cells in vivo and subsequent protective immune mechanisms. Thus these results emphasize the critical functions of accessory cells in determining the outcome of malaria infections.     

Slowing of the Ventricular Rate During Atrial Fibrillation by Ablation of the Slow Pathway of AV Nodal Reentrant Tachycardia

Influence of Slow Pathway Ablation on Atrial Fibrillation. Introduction : The mechanisms whereby radiofrequency catheter modification of AV nodal conduction slows the ventricular response are not well defined. Whether a successful modification procedure can be achieved by ablating posterior inputs to the AV node or by partial ablation of the compact AV node is unclear. We hypothesized that ablation of the well-defined slow pathway in patients with AV nodal reentrant tachycardia would slow the ventricular response during atrial fibrillation.
Methods and Results : In 34 patients with dual AV physiology and inducible AV nodal reentrant tachycardia, atrial fibrillation was induced at baseline and immediately after successful slow pathway ablation and at 1-week follow-up. The minimal, maximal, and mean RR intervals during atrial fibrillation increased from 353 ± 76,500 ± 121, and 405 ± 91 msec to 429 ± 84 (P < 0.01), 673 ± 161 (P < 0.01), and 535 ± 98 msec (P < 0.01), respectively. These effects remained stable during follow-up at 1 week. The AV block cycle length increased from 343 ± 68 msec to 375 ± 60 msec (P < 0.05) immediately and to 400 ± 56 msec (P < 0.01) at 1-week follow-up. The effective refractory period of the AV node prolonged from 282 ± 83 msec to 312 ± 89 msec and to 318 ± 81 msec after 1 week (P < 0.05), respectively.
Conclusion : This study shows a decrease in ventricular response to pacing-induced atrial fibrillation after ablation of the slow pathway in patients with AV nodal reentrant tachycardia. Since the AV nodal conduction properties could be defined, this study supports the hypothesis that the main mechanism of AV nodal modification in chronic atrial fibrillation is caused by ablation of posterior inputs to the AV node.     

Change in the retrograde atrial activation sequence following radiofrequency modification of the atrioventricular node: implications for the electrophysiologic circuit of a variant of atrioventricular nodal reentrant tachycardia

INTRODUCTION: Despite the great success in treating AV nodal reentrant tachycardia (AVNRT) with radiofrequency modification of the AV node, the dimensions of the electrophysiologic circuit of this arrhythmia remain unclear, and simple models fail to explain all tachycardia-related phenomena. METHODS AND RESULTS: We describe three unusual cases of supraventricular tachycardia (SVT). In all three cases, retrograde atrial activation during ventricular pacing or during SVT manifested local left atrial electrograms recorded from the coronary sinus preceding the septal atrial electrograms (eccentric activation), with earliest atrial activity at the lateral or posterolateral mitral annulus. Electrophysiologic maneuvers and observations were consistent with AVNRT as the mechanism in each case. In all cases, radiofrequency modification of the AV node eliminated inducible SVT and abolished dual pathway AV nodal physiology. The retrograde atrial activation sequence during ventricular pacing changed after ablation in each case, with septal atrial electrograms preceding left atrial electrograms recorded from the coronary sinus (concentric activation). CONCLUSION: The observations in these cases cannot be explained by the traditional model of slow, fast, and intermediate AV nodal pathways. A model incorporating a circuit close to the AV node with left atrial and coronary sinus connections is proposed.     

Reported normal values and weighted means for commonly used echocardiography pulsed Doppler and tissue Doppler measurements

Pulsed Doppler (PW) and tissue Doppler imaging (TDI) measurements are part of every echocardiography examination for evaluation of left ventricular (LV) diastolic function and filling pressure. The purpose of this study was to summarize published data on normal values for PW and TDI measurements. A PubMed search was performed on the 10th of October 2016 to identify relevant articles. Studies were considered relevant if they included more than 200 healthy individuals. A total of 13 studies were identified. Of these, 13 studies with 7777 subjects reported PW measurement over the mitral valve, six studies with 4082 subjects reported PW measurement in the pulmonary vein and 10 studies with 5988 subjects reported TDI. We also report weighted mean values for 14 different variables. As expected, measurements varied with age. There were no major differences between men and women. In contrast, there was a large difference in reported values between studies, in corresponding age groups. This review therefore raises caution about relying on normal values from just one study.     

Trigeminal Neuralgia in Pregnancy: A Management Challenge

Pregnancy is known to aggravate pre‐existing chronic painful conditions. Trigeminal neuralgia (TN), albeit a disease of the elderly, may afflict pregnant females, which can further complicate its management. Teratogenic effects of the commonly used drugs on the developing fetus limit pharmacological treatment. Moreover, safety of commonly performed interventional therapies is marred by their inherent fetomaternal effects and more importantly the risk for radiation effects on the fetus due to the use of fluoroscopy. This rare coexistence of TN in pregnancy has not been reported before. Here we present a case of TN in a young woman, whose pain was aggravated when she became pregnant, and she was treated successfully by conventional radiofrequency ablation of the Gasserian ganglion.     

超声引导经皮双极射频消融治疗良性甲状腺结节的局部疗效观察

正甲状腺良性结节通常无需处理,但随着结节增大可能影响美观或有压迫不适感,此时多需要治疗。射频消融(radiofrequency ablation,RFA)作为一种微创治疗方式,目前临床已广泛用于甲状腺结节的治疗~([1])。本组旨在对行超声引导经皮双极RFA治疗的良性甲状腺结节的局部疗效进行分析。     

右美托咪定复合瑞芬太尼在软组织射频热凝+拨针治疗中的应用

目的观察右美托咪定复合瑞芬太尼用于软组织射频热凝+拨针治疗的临床效果。方法选择行软组织射频热凝+拨针治疗的患者60例,依麻醉方式分为咪达唑仑复合瑞芬太尼组(A组)和右美托咪定复合瑞芬太尼组(B组),每组各30例。记录给药前(T0)、给药后5 min(T1)、10 min(T2)、30 min(T3)、50 min(T4)各时点心率(HR),指脉氧饱和度(SPO2),无创平均动脉压(MAP),呼吸频率(RR),手术时间,苏醒时间,瑞芬太尼的总用量,麻醉后不良反应及并发症,患者苏醒即刻视觉疼痛评分(VAS)。结果两组RR、SPO2、手术时间、苏醒时间无差异性;与T0相比,两组T1时点的RR、HR、MAP均下降(P<0.05);与A组相比,B组MAP、HR下降(P<0.05),不良反应发生率,瑞芬太尼总用量B组少于A组(P<0.05),患者苏醒即刻视觉疼痛评分(VAS)B组低于A组(P<0.05)。结论右美托咪定复合瑞芬太尼用于软组织射频热凝+拨针治疗,是一种安全有效的清醒镇静镇痛方法,值得临床推广。     

Safety and efficacy analysis of one‐stop intervention for treating nonvalvular atrial fibrillation

1 Background

Nonvalvular atrial fibrillation (AF) is a common arrhythmia. The treatment strategy for AF mainly includes controlling symptoms and decreasing the rate of complications. Our study aimed to evaluate the safety and efficacy of combination treatment of catheter ablation and left atrial appendage (LAA) closure (one‐stop intervention) in patients with nonvalvular AF.

2 Methods and results

Thirty‐four patients with symptomatic AF (mean CHA₂DS₂‐VASc score 4.1 ± 1.3, mean HAS‐BLED score 3.8 ± 1.2) were included. Patients first received radiofrequency‐based left atrial ablation, and then the Watchman device (Boston Scientific, Natick, MA, USA) or AMPLATZER Cardiac Plug (ACP) (St. Jude Medical, Inc., St. Paul, MN, USA) was implanted for LAA closure. Follow‐up was performed at 45 days and 3 months after LAA closure to assess for recurrence of AF and prevent stroke. Radiofrequency ablation and LAA closure were successful in 100% of patients without evidence of residual flow at the final transesophageal echocardiography evaluation. A Watchman device was implanted in 29 (85.3%) patients, and an ACP was implanted in five (14.7%) patients. No device‐related thrombus formation or embolization was identified at the 45‐day or 3‐month follow‐up. Serious complications, including death, transient ischemic attack, ischemic or hemorrhagic stroke, or major bleeding, were also not identified during the follow‐ups.

3 Conclusion

For symptomatic patients with nonvalvular AF and a high risk of stroke, the one‐stop intervention is feasible, safe, and efficacious.