Change in Size of Lesions Over 3 Weeks After Radiofrequency Ablation of Left Ventricle

Myocardial Injury Progression after Radiofrequency Ablation in School-Age Children

BACKGROUND

The past decades have seen the rapid development of the invasive treatment of arrhythmias by catheter ablation procedures. Despite its safety and efficacy being well-established in adults, to date there has been little data in pediatric scenarios. One of the main concerns is the possible expansion of the ablation procedure scar in this population and its consequences over the years.

OBJECTIVES

This study aimed to analyze the risk of myocardial injury progression after radiofrequency catheter ablation in pediatric patients.

METHODS

This is a retrospective study of 20 pediatric patients with previous ablation for treatment of supraventricular arrhythmia that underwent cardiac magnetic resonance and coronary angiography for evaluation of myocardial fibrosis and the integrity of the coronary arteries during follow-up.

RESULTS

The median age at ablation procedure was 15.1 years (Q1 12.9, Q3 16.6) and 21 years (Q1 20, Q3 23) when the cardiac magnetic resonance was performed. Fourteen of them were women. Nodal reentry tachycardia and Wolf-Parkinson-White Syndrome were the main diagnosis (19 patients), with one patient with atrial tachycardia. Three patients had ventricular myocardial fibrosis, but with a volume < 0.6 cm 3 . None of them developed ventricular dysfunction and no patient had coronary lesions on angiography.

CONCLUSION

Radiofrequency catheter ablation did not show to increase the risk of myocardial injury progression or coronary artery lesions.

Tissue-Specific Optical Mapping Models of Swine Atria Informed by Optical Coherence Tomography

Computational models and experimental optical mapping of cardiac electrophysiology serve as powerful tools to investigate the underlying mechanisms of arrhythmias. Modeling can also aid the interpretation of optical mapping signals, which may have different characteristics with respect to the underlying electrophysiological signals they represent. However, despite the prevalence of atrial arrhythmias such as atrial fibrillation, models of optical electrical mapping incorporating realistic structure of the atria are lacking. Therefore, we developed image-based models of atrial tissue using structural information extracted from optical coherence tomography (OCT), which can provide volumetric tissue characteristics in high resolution. OCT volumetric data of four swine atrial tissue samples were used to develop models incorporating tissue geometry, tissue-specific myofiber orientation, and ablation lesion regions. We demonstrated the use of these models through electrophysiology and photon scattering simulations. Changes in transmural electrical conduction were observed with the inclusion of OCT-derived, depth-resolved fiber orientation. Additionally, the amplitude of optical mapping signals were not found to correspond with lesion transmurality because of lesion geometry and electrical propagation occurring beyond excitation light penetration. This work established a framework for the development of tissue-specific models of atrial tissue derived from OCT imaging data, which can be useful in future investigations of electrophysiology and optical mapping signals with respect to realistic atrial tissue structure.

Extracellular matrix collagen I promotes the tumor progression of residual hepatocellular carcinoma after heat treatment

Background

Accelerated malignant behaviors induced by insufficient thermal ablation have been increasingly reported, however, the exact mechanisms are still unclear. Here, we investigated the importance of the extracellular matrix (ECM) in modulating the progression of residual hepatocellular carcinoma (HCC) after heat treatment.

Methods

Heat-exposed residual HCC cells were cultured in different ECM gels. We used basement membrane gel (Matrigel) to simulate the normal microenvironment and collagen I to model the pathological stromal ECM. The alterations of morphology and parameters of proliferation, epithelial-mesenchymal transition (EMT) and stemness were analyzed in vitro and in vivo.

Results

Increased collagen I deposition was observed at the periablational zone after incomplete RFA of HCC in a xenograft model. The markers of cell proliferation, EMT, motility and progenitor-like traits of heat-exposed residual HCC cells were significantly induced by collagen I as compared to Matrigel (p values all < 0.05). Importantly, collagen I induced the activation of ERK phosphorylation in heat-exposed residual HCC cells. ERK1/2 inhibitor reversed the collagen I-promoted ERK phosphorylation, cell proliferative, protrusive and spindle-like appearance of heat-treated residual HCC cells in vitro. Moreover, collagen I promoted the in vivo tumor progression of heat-exposed residual HCC cells, and sorafenib markedly reversed the collagen I-mediated protumor effects.

Conclusions

Our findings demonstrate that collagen I could enhance the aggressive progression of residual HCC cells after suboptimal heat treatment and sorafenib may be a treatment approach to thwart this process.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4820-9) contains supplementary material, which is available to authorized users.

Radiofrequency ablation in snoring surgery: local tissue effects and safety measures

Radiofrequency ablation is now widely used in the treatment of patients with snoring and obstructive sleep apnoea. It is well suited to the multilevel approach typically required in snoring surgery and can be used interstitially or in cutting mode. However, no research has been performed to analyse the collateral local tissue damage or size of lesions induced by radiofrequency application. This is the first study of the histological effects of interstitial radiofrequency. We studied the size of tissue lesions generated at differing power settings with and without local anaesthetic application in human tonsils and chicken breast tissue. The size of the lesion was independent of power setting and local anaesthetic infiltration. The typical effect was an oval-shaped lesion centred on the active electrode, 6-7 mm in width and 7-8 mm in length. This was confirmed histopathologically, with smaller lesions generated in the submucosa (2 × 3 mm) but with no collateral tissue damage beyond this distinct zone of injury. To avoid complications, we recommend placing contiguous radiofrequency applications at least 8 mm apart. Post-nasal space packing raises and tautens the soft palate. The use of local anaesthetic increases interstitial volume, thereby reducing the risk of incorrect probe placement and resultant ulceration or fistulation.