紫外激光消融过程的等效模型研究

本文引用等效模型,对激光消融过程进行了推导与计算,和实验结果比较表明,所得公式与实验结果能较好相符,可用于描述紫外激光消融过程。     

Ablation of Premature Ventricular Complexes Triggering Ventricular Fibrillation in a Patient with Long QT Syndrome

We describe the case of a patient with long QT syndrome and recurrent ventricular fibrillation, triggered by premature ventricular complexes (PVCs) with a left bundle branch block pattern and inferior axis of the QRS. Activation mapping demonstrated the origin of the PVCs to be in the right ventricular outflow tract. Ventricular fibrillation (VF) was successfully treated by catheter ablation of the triggering PVCs and there has been no recurrence of VF during a follow-up period of 14 months.     

Cryoballoon ablation for atrial fibrillation

Focal point-by-point radiofrequency catheter ablation has shown considerable success in the treatment of paroxysmal atrial fibrillation. However, it is not without limitations. Recent clinical and preclinical studies have demonstrated that cryothermal ablation using a balloon catheter (Artic Front©, Medtronic CryoCath LP) provides an effective alternative strategy to treating atrial fibrillation. The objective of this article is to review efficacy and safety data surrounding cryoballoon ablation for paroxysmal and persistent atrial fibrillation. In addition, a practical step-by-step approach to cryoballoon ablation is presented, while highlighting relevant literature regarding: 1) the rationale for adjunctive imaging, 2) selection of an appropriate cryoballoon size, 3) predictors of efficacy, 4) advanced trouble-shooting techniques, and 5) strategies to reduce procedural complications, such as phrenic nerve palsy.     

Dual energy computed tomography thermometry during hepatic microwave ablation in an ex-vivo porcine model

BackgroundMicrowave thermoablation (MTA) is a treatment method used to destroy hepatic tumors.ObjectiveTo investigate temperature changes during MTA of ex-vivo porcine liver using dual-energy computed tomography (DECT) imaging.MethodsThree MTA experiments were performed using ex-vivo porcine liver (15 × 15 × 15 cm³) and DECT imaging with 80/Sn140 kVp spectral and 0.5-weighted reconstructions. Images were acquired from basic organ temperature to 100 °C with 10 °C difference during microwave heating and cooling phases. Three fluoro-optic thermometers were used for temperature measurements; two were placed at 1 cm and third one positioned at 2 cm distance from the applicator. Tissue temperature, ablation-region-conspicuity (ARC), ablation-region dimensions and image quality were determined. Regression analysis was performed determining thermal sensitivity during heating and cooling phases.ResultsDetermined thermal sensitivities during heating phase were: −0.59 Hounsfield Unit/°C (80 kVp), −0.60HU/°C (0.5-weighted) and −0.59HU/°C (140 kVp); furthermore, during cooling: −0.56HU/°C (80 kVp), −0.55HU/°C (0.5-weighted) and −0.55HU/°C (140 kVp). ARC showed significantly higher (all P < 0.05) values for thermometer positions −1 and −2 compared to −3; however, comparison between positions −1 and −2 was insignificant (P > 0.05). Signal-to-noise ratios were higher for 0.5-weighted but ARC values were higher for 80 kVp images.ConclusionMicrowave thermal sensitivity on tissue was inversely linear with DECT image datasets. Heating phase showed higher influence of temperature on HU compared to cooling; ARC and ablation-region were increased with increase in temperature.     

Atrial fibrillation and preexcitation - A licence to kill

Atrial fibrillation becomes a potentially lethal arrhythmia in the presence of preexcitation because the rapid ventricular activation can result in ventricular fibrillation. Fortunately, radiofrequency ablation is an effective treatment for these patients. Specific points of interest regarding this association are the mechanism of increased incidence of atrial fibrillation and the current management of patients presenting in atrial fibrillation. These are discussed in this editorial.     

XeCl准分子激光消融几种生物组织的实验结果

本文报道了３０８ｎｍＸｅＣｌ准分子激光对人牙硬组织和猪肉软组织消融的实验研究结果,在国内首次开展了ＸｅＣｌ准分子激光牙科应用的基础研究,为准分子激光在牙科的临床应用提供了实验依据。     

Cryoablation in persistent atrial fibrillation – a critical appraisal

Ablation of atrial fibrillation is an established treatment for the management of patients with paroxysmal and persistent atrial fibrillation. The complex pathophysiology of persistent atrial fibrillation has fuelled the concept of adjunctive substrate modification on top of pulmonary vein isolation. However, recent studies have failed to demonstrate additive benefit from complex ablation approaches, thus supporting that standalone pulmonary vein isolation may prove sufficient, at least as the initial ablation strategy in persistent atrial fibrillation. In this premise, the new-generation cryoballoon is an attractive option in this demanding subgroup of patients due to its reliable efficacy in achieving pulmonary vein isolation combined with collateral debulking of the neighbouring atrial myocardium. In this review, we present a critical appraisal of the role of cryoablation in patients with persistent atrial fibrillation, discussing related technical considerations and existing scientific evidence.     

Reversal of ventricular premature beat induced cardiomyopathy by radiofrequency catheter ablation

Frequent monomorphic ventricular premature beats (VPBs) may lead to left ventricular dysfunction. We describe two patients with frequent monomorphic VPBs and dilated cardiomyopathy in whom left ventricular function normalised after elimination of the VPBs by radiofrequency catheter ablation. The recent literature on this topic is summarised and potential candidates for catheter ablation are discussed. (Neth Heart J 2010;18:493-8.)     

Double-gap-in-roof reentrant tachycardia following surgical thoracoscopic atrial fibrillation ablation

A case of macro-reentrant tachycardia associated with a box lesion after thoracoscopis left atrial surgical atrial fibrillation (AF) ablation yet to be described. The goal was to clarify the mechanisms and electrophysiological characteristics of this type of tachycardia.A patient was admitted for an EP study following surgical thoracoscopic AF ablation (box lexion formation by right-sided Cobra thoracoscopic ablation). Thoracoscopic ablation was done as the first step of the hybrid ablation approach to the persistent AF; the second step was the EP study. At the EP study, he presented with incessant regular tachycardia (cycle length of 226 ms). An EP study with conventional, 3D activation and entrainment mapping was done to assess the tachycardia mechanism. Two conduction gaps in the superior line (roofline) between the superior pulmonary veins were discovered. The tachycardia was successfully treated with a radiofrequency application near the gap close to the left superior pulmonary vein; however, following tachycardia termination, pulmonary vein isolation was absent. A second radiofrequency application, close to the roof of the right superior pulmonary, vein closed the gap in the box and led to the isolation of all 4 pulmonary veins. No atrial tachycardia recurred during the 6-month follow-up.Conduction gaps in box lesion created by thoracospcopic ablation can present as a novel type of man-made tachycardia after surgical ablation of atrial fibrillation. Activation and entrainment mapping is necessary for an accurate diagnosis.     

Epicardial Ablation of Focal Atrial Tachycardia Arising From Left Atrial Appendage in Children

Focal left atrial tachycardia (FLAT) although a common cause of supraventricular tachycardia(SVT) among children, the one''s arising from left atrial appendage (LAA) present a unique challenge for successful ablation because of anatomical location. We present two children with FLAT arising from the epicardial LAA, successfully mapped and ablated through percutaneuous epicardial approach.     

Catheter Ablation in Patients with Electrical Storm in Early Post Infarction Period (6 Weeks): A Single Centre Experience

Background

Electrical storm (ES) due to drug refractory ventricular tachycardia (VT) occurring within first few weeks of acute myocardial infarction (MI) has poor prognosis. Catheter ablation has been proposed for treating VT occurring late after MI, but there is limited data on catheter ablation in VT within first few weeks of MI.

Methods and Results

Five patients (4 males, mean age 54.2±12.11 years) between June 2008 to July 2012, referred for VT presenting as ES refractory to antiarrhythmic drugs in the early post infarction period (six weeks following MI) despite revascularization. Three patients had anterior wall MI and two inferior wall MI with left ventricular ejection fraction ranging from 26 to 35%.All underwent catheter ablation within 48 hours of being in VT except one who presented late. Clinical VT was induced in all five patients. Total number of VTs induced were 11 (2.2±1.09 per patient). Two patients needed epicardial ablation via pericardial puncture. Though acute success was 100%, one patient had recurrence of clinical VT the next day of procedure.One patient succumbed to sepsis with multiple organ failure. The remaining four patients are doing well without further clinical recurrence of VT over a period of 3.7 years of follow-up.

Conclusion

Catheter ablation can be a useful adjunctive therapy for patients with recurrent VT in the early post infarction period. This procedure appears to be safe with acceptable success rate.     

Improved Flutter Ablation Outcomes Using a 10mm-tip Ablation Catheter

Introduction

Radiofrequency(RF) ablation has become the first line of therapy for atrial flutter(AFL). Advances in catheter and mapping technologies have led to better understanding and different approaches for treating this arrhythmia. We describe the results of different approaches to ablate this arrhythmia.

Materials and Methods

A cohort of 198 patients with isthmus dependent AFL. The techniques used were: 10mm-tip catheter with power set to 100w, 8mm-tip catheter with power set to 60W and irrigated tip catheter.

Results

212 procedures, including redos were done in 198 consecutive patients. We used irrigated tip catheters in 14 procedures, 8mm-tip in 55 procedures, and 10mm-tip in 143 procedures. Bidirectional block was achieved in 97.6% of cases with all techniques, with no difference among them. Procedure time was shorter in the 10mm-tip versus 8mm-tip(69.6±30.6min vs.105±43min) or irrigated tip(180±90min) (P<0.05). Fluoroscopy time was also shorter in the 10mm-tip versus 8mm-tip (24±18min vs. 37±23min) or irrigated tip (110±25min)(P<0.05). The cumulative incidence of failure during follow-up was 1.2%/year in the 10mm, 10.1%year in the 8mm and 6.9%year in the irrigated tip. The survival free of a new procedure was significantly higher among 10mm patients.

Conclusions

In our series we found a high rate of acute success with the use of different techniques for AFL ablation. Procedure and fluoroscopic times were shorter with the use of 10mm-tip as compared with the others techniques. The long-term risk of recurrence was lower when we used the 10mm-tip catheter and the survival free of a second procedure was higher among patients treated with this catheter.     

Evaluation of the Serratia Marcescens Nuclease (NucA) as a Transgenic Cell Ablation System in Porcine

The efficiency of the Serratia marcescens nuclease encoded by the NucA gene, with or without a nuclear localization signal (NLS), and the commonly used diphtheria toxin A (DTA) were compared for their ability to ablate cells in culture. Constructs containing the test genes driven by the β-actin promoter coupled with enhancer elements from the cytomegalovirus promoter and rabbit β-globin gene (pCAG) and the blasticidin resistance gene driven by the phosphoglycerate kinase (PGK) promoter were generated and electroporated into porcine fetal fibroblasts. Three independent replicates were completed. Following blasticidin selection, the number of surviving colonies was counted to assess the efficiency of the toxic gene. Both NucA and DTA proved to be effective in killing porcine fibroblasts compared to controls. However, the efficiency of cell ablation was significantly higher with DTA than with NucA or NucANLS (p < 0.05). Gene expression analysis of surviving colonies indicated that survival is related to low or absent expression of the toxic genes. These results indicate that the NucA gene, while capable of mammalian cell ablation, is less efficient than DTA.