Ventricular fibrillation treated by cryotherapy to the right ventricular outflow tract: a case report

Assessment of a novel cryoablation device for the endovascular treatment of cardiac tachyarrhythmias

Objectives

Cryoablation is an effective alternative treatment for cardiac arrhythmias offering shortened recovery and reduced side effects. As the use of cryoablation increases, the need for new devices and procedures has emerged. This has been driven by technological limitations including lengthy periods to generate a single lesion (3-5 min), uncertain transmurality, and differential efficacy. Furthermore, due to limited ablation capacity under high heat loads, cryo has had limited success in the treatment of ventricular arrhythmias. To this end, in this study we evaluated a new cryoablation catheter, ICEolate, for the targeted ablation of cardiac tissue.

Methods

Performance assessment included calorimetry, freeze zone isothermal distribution characterization and catheter ablation capacity in a submerged, circulating, heat-loaded ex vivo tissue model. A pilot in vivo study was also conducted to assess ablative capacity of the cryocatheter in a fully beating heart.

Results

Ex vivo studies demonstrated ice formation at the tip of a cryocatheter within 5 s and a tip temperature of ~-150°C within 10 s. The device repeatedly generated freeze zones of 2 cm × 3 cm in less than 2 min. Tissue model studies revealed the generation of a full thickness (5-10 mm) cryogenic lesion within 1 min with an opposite (transmural) surface temperature of <-60°C under a circulating 37°C heat load. Pilot in vivo studies demonstrated the delivery of an ablative "dose," producing a continuous full thickness transmural linear lesion in <60 s at both atrial and ventricular sites.

Conclusion

These studies suggest that the supercritical nitrogen cryodevice and ICEolate cryocatheter may provide for rapid, effective, controllable freezing of targeted tissue. The ablative power, speed, and directional freeze characteristics also offer the potential of improved safety via a reduction in procedural time compared to current cryoablation devices. These technological developments may open new avenues for the application of cryo to treat other cardiac arrhythmogenic disorders.

Stylistic features of case reports as a genre of medical discourse

Background

The present paper discusses the lexical and grammatical peculiarities of English language medical case reports, taking into account their communicative purposes and intentions.

Methods

The objective of the research is to clarify the principal mechanisms of producing an effective English language medical case report and thus to provide recommendations and guidelines for medical professionals who will deal with this genre. The analysis of medical case reports will largely focus on the most significant linguistic peculiarities, such as the use of active and passive voice, the choice of particular verb tenses, and pronouns. The selected medical case reports will be considered using methods of lexico-grammatical analysis, quantitative examination, and contextual, structural, narrative, and stylistic analyses.

Results

The research revealed a range of important stylistic features of medical case reports which markedly distinguish them from other genres of medical scientific writing: educational and instructive intentions, conciseness and brevity, direct and personal tone, and material presented in a narrative style. The present research has shown that the communicative strategies of the analyzed discourse, mentioned immediately above, are effectively implemented by means of specific lexical units and grammatical structures: the dominance of active voice sentences, past simple tense, personal pronouns, and modal verbs. The research has also detected the occasional use of the present perfect, present simple, and future simple tenses and passive voice which also serve particular communicative purposes of medical case reports.

Conclusions

Medical case reports possess a range of unique characteristics which differ from those of research articles and other scientific genres within the framework of written medical discourse. It is to be emphasized that it is highly important for medical professionals to master the major stylistic principles and communicative intentions of medical case report as a genre in order to share their findings with fellow researchers from all over the world. Hence, in the process of training future medical researchers, the analysis of the basic mechanisms of writing a medical case report should be an integral part of the curricula in English for Specific Purposes at universities.