Einfluss der dreifachen Kryoenergieapplikation auf die Formation von Ablationsläsionen und die Koronarperfusion am wachsenden Myokard

Impact of Triple Cryoablation on Ablation Lesion Formation and Coronary Perfusion in the Developing Myocardium

by Clemens Grimm
Doctoral thesis
Date of Examination:2025-01-16
Date of issue:2024-12-16
Advisor:PD Dr. Ulrich Krause
Referee:Prof. Dr. Markus Zabel
Referee:Prof. Dr. Thomas Meyer
Persistent Address: http://dx.doi.org/10.53846/goediss-10955

 

 

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Abstract

English

Supraventricular tachycardias (SVT) are the most common tachyarrhythmias in pediatric patients. The estimated incidence ranges between 0.1% and 0.4% (Albinni et al., 2010). Given the significant impact these rhythm disorders can have on the quality of life of affected children and their families, advancing the analysis and optimization of SVT therapy in this patient population is of utmost importance. Currently, two ablation techniques are available for the treatment of SVT in children and adolescents: radiofrequency (RF) ablation and cryoablation (Collins et al., 2006; Santangeli et al., 2014). While cryoablation has been shown to be somewhat less effective in the long term compared to RF ablation, it is a gentler method associated with fewer complications. The recurrence rate following cryoablation ranges from approximately 7–29%, with reported success rates between 62–92% (Brugada et al., 2013). In contrast, RF ablation demonstrates a lower recurrence rate of 5–10% and an acute success rate exceeding 90% (Brugada et al., 2013). Overall, cryoablation has a superior safety profile compared to RF ablation, albeit with the trade-off of lower success rates and higher recurrence rates (Andrade et al., 2013). Determining the optimal number of freezing and thawing sequences that maximize long-term efficacy while minimizing complications remains an ongoing challenge. It is hypothesized that additional freezing and thawing cycles may enlarge the lesions created, thereby increasing both the acute success rate and long-term efficacy. Previous studies conducted by our research group have supported this hypothesis with findings on double cryoablation (Schneider et al., 2013; Schneider et al., 2019). Consequently, this study explored a further modified approach employing triple cryoablation, involving three freeze-thaw cycles, with follow-up analysis performed six months later. The study cohort consisted of five pigs. A total of 31 lesions were detected in the five pig hearts after paraffin embedding and were examined macroscopically and microscopically. Neither intracardiac ultrasound (ICUS), coronary angiography, nor macroscopic assessments revealed any significant complications, such as thromboses, hemorrhages, or coronary vessel involvement. Detailed histological analysis of the lesions corroborated these findings. Volumetric analysis of the lesions allowed comparison with data from previous studies by our group. Compared to RF ablation (Paul et al., 1997), single cryoablation (Kriebel et al., 2005; Kriebel et al., 2010), and early results from double cryoablation (Schneider et al., 2013), significantly larger lesion volumes were observed in this study. While the lesion volumes at six months post-triple cryoablation were larger than those observed 48 hours after triple cryoablation (Krause et al., 2017), this difference did not reach statistical significance. Lesion volumes at six months post-triple cryoablation were comparable to those observed six months post-double cryoablation (Schneider et al., 2019). This study demonstrated that triple cryoablation did not lead to a significant further increase in lesion volumes compared to double cryoablation after six months. Future studies involving larger cohorts and direct comparisons between the different methods are necessary to further validate these findings.
Keywords: Cryoablation; Supraventricular Tachycardia