Abstract

To compare the effectiveness of early termination (ET) and standard termination (ST) of radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) using internally cooled electrodes. Eighty-three treatment naïve patients with HCC with 101 index tumor underwent RFA. ET was defined as termination of ablation if after 6 minutes the power emission was < 10 seconds for three times per minute under maximal power. Standard termination was defined as termination of ablation according to manufactures’ algorithms of 12 minutes’ procedure. Primary end point was complete ablation of index tumor after 4 weeks of RFA. Nineteen patients (22.9%) underwent ET and 64 patients (77.1%) underwent ST. The mean size of the index tumor was 2.2 + 0.9 cm. Patient had complete ablation of the index tumor at 92.0% for the ET and 88.2% for the ST (p = 0.593). Eight of 25 (32.0%) for the ET and 18 of 73 (24.7%) for the ST group had local tumor progression on last follow-up (p = 0.473). After a median follow-up of 23 weeks (range, 9–33 weeks), the 24 weeks cumulative probability of local tumor progression was not different between ET (46.2%) and ST (25.6%, p = 0.387). Complete ablation at 4 weeks was the only independent factor associated with local tumor progression (adjusted hazard ratio 0.04, 95% confidence interval 0.01–0.16, p < 0.001). Using ET in RFA is as effective as the ST in achieving complete ablation and local tumor progression.

Abstract

Esophageal cancer is a common and highly lethal disease. In the Asia-Pacific region, esophageal squamous cell neoplasias are the major forms of the disease. Recent advances in endoscopic therapy enable curative treatment of early esophageal squamous cell neoplasias, however, the technique is complicated and requires a high level of expertise, especially for those with long-segment lesions. Endoscopic radiofrequency ablation is a rapidly evolving treatment modality and has been shown to have good efficacy and safety for the treatment of dysplasia in cases of Barrett’s esophagus. Theoretically, it can also be used to treat squamous dysplasia. We report a case of a 48-year-old man with an 8-cm-long circumferential squamous high-grade dysplasia over the esophagus (from 21 cm to 29 cm below the incisor) that was treated successfully and safely with balloon-based radiofrequency ablation. The procedure took only around 30 minutes to complete. There were no major adverse events during and after the procedure. In addition, we examined the histology of the esophageal coagulum, which showed an extensive cauterization effect with focal dysplasia within the ablated epithelium. Follow-up endoscopy at 1 month, 3 months, and 6 months showed no residual lesion, and biopsies also confirmed complete remission.

Abstract

In light of recent reports showing high incidence of silent cerebral infarcts and organized atrial arrhythmias following radiofrequency (RF) atrial fibrillation (AF) ablation, a review of its safety aspects is timely. Serious complications do occur during supraventricular tachycardia (SVT) ablations and knowledge of their incidence is important when deciding whether to proceed with ablation. Evidence is emerging for the probable role of prophylactic ischemic scar ablation to prevent VT. This might increase the number of procedures performed. Here we look at the various complications of RF ablation and also the methods to minimize them. Electronic database was searched for relevant articles from 1990 to 2015. With better awareness and technological advancements in RF ablation the incidence of complications has improved considerably. In AF ablation it has decreased from 6% to less than 4% comprising of vascular complications, cardiac tamponade, stroke, phrenic nerve injury, pulmonary vein stenosis, atrio-esophageal fistula (AEF) and death. Safety of SVT ablation has also improved with less than 1% incidence of AV node injury in AVNRT ablation. In VT ablation the incidence of major complications was 5–11%, up to 3.4%, up to 1.8% and 4.1–8.8% in patients with structural heart disease, without structural heart disease, prophylactic ablations and epicardial ablations respectively. Vascular and pericardial complications dominated endocardial and epicardial VT ablations respectively. Up to 3% mortality and similar rates of tamponade were reported in endocardial VT ablation. Recent reports about the high incidence of asymptomatic cerebral embolism during AF ablation are concerning, warranting more research into its etiology and prevention.

Abstract

Radiofrequency ablation is a medical procedure that is becoming increasingly used for disease treatments. During this procedure, part of dysfunctional tissues is ablated by using the heat, typically generated from medium frequency electric current. It is a field of medicine where mathematical and computational models play a substantial role in assisting clinical practitioners with quantifications of some of the most critical characteristics, including temperature distributions and ablated volumes. In this contribution, we describe a framework for the development of coupled thermo-electro-mechanical models in this field. While our framework and the described validation procedures can be applicable to a variety of ablation modalities and treatments, a major focus has been given to some of the pecularities related to cardiac ablation at tissue-cellular scales and a role played by cell organelles such as microtubules, as well as by the cell nucleus. We have discussed the effects their inclusion makes on the calculation of the main characteristics of the radiofrequency ablation procedures. The importance of domain heterogeneity, as well as the integration of fluid-structure interaction in the developed framework along with other effects, have been highlighted and the details on ablation modalities in the context of clinical experimental research have been given. Finally, future generalizations of the proposed framework with hybrid stochastic-deterministic models have been put forward.