Using coronary sinus ostium as the reference for the slow pathway ablation of atrioventricular nodal reentrant tachycardia in children

Combination of Slow Pathway Late Activation Maps and Voltage Gradient Maps in Guidance of Atrioventricular Nodal Reentry Tachycardia Cryoablation

BACKGROUND

The optimal strategy for electroanatomic mapping-guided cryoablation of atrioventricular nodal reentry tachycardia (AVNRT) remains unclear.

OBJECTIVE

To investigate the effectiveness of slow pathway late activation mapping (SPLAM) and voltage gradient mapping for AVNRT cryoablation.

METHODS

From June 2020 to February 2022, all consecutive patients with AVNRT underwent SPLAM to define the wave collision point and voltage gradient mapping to define the low voltage bridge (LVB). Conventional procedures performed from August 2018 to May 2020 served as control.

RESULTS

The study and control groups comprised 36 (aged 16.5±8.2 years) and 37 patients (aged 15.5±7.3 years), respectively. Total procedural times were comparable, and acute success rates were 100% in both groups. Compared to controls, number of cryomapping attempts (median 3 vs. 5, p=0.012) and cryoablation applications (median 1 vs. 2, p<0.001) were significantly lower in the study group. At a median follow-up of 14.6 and 18.3 months, recurrence rates were 5.6% (2 patients) and 10.8% (4 patients) in the study and control groups (p=0.402), respectively. Mapping of Koch's triangle took 11.8±3.6 min, in which 1562±581 points were collected. In SPLAM, wave collision points were defined and compatible with the final successful lesion sites in all patients, including those with multiple slow pathways. LVB could not be defined in 6 patients (16.7%), and LVB was not compatible with the final successful lesion in another 6 (16.7%).

CONCLUSIONS

For AVNRT cryoablation, SPLAM could effectively guide the localization of slow pathway ablation sites and was particularly beneficial in patients with multiple slow pathways.

Electrogram characteristics at successful cryoablation sites in slow-fast atrioventricular nodal reentrant tachycardia

PURPOSE

Cryoablation is a safe alternative to radiofrequency (RF) ablation for slow-fast atrioventricular reentrant tachycardia (AVNRT); however, optimal electrogram parameters for site selection remain unknown. We retrospectively investigated local electrograms for slow pathway (SP) modification in cryoablation.

METHODS

Forty-five consecutive patients with slow-fast AVNRT who underwent cryoablation using a 6-mm-tip catheter were enrolled. Electrogram parameters for sites of successful SP modification (success-sites) were investigated; these included the interval between atrial activation at His and the last deflection of SP potential, defined as the His(A)-SPP interval. In 8 patients, 3-dimensional mapping by multi-electrode catheter was performed pre-ablation for more detailed SP assessment.

RESULTS

Twenty-seven of 45 patients had successful SP modification by 1 cycle of freeze-thaw-freeze cryoablation at a single site with a low amplitude and fragmented SP potential. Among a total of 76 cryoablation sites in all patients, the His(A)-SPP interval at success-sites (45 sites) was significantly longer than that at unsuccess-sites (31 sites) (86 ± 9 vs.78 ± 10 msec, p < 0.0001). The AV amplitude ratio was not significantly different between success-and unsuccess-sites (0.21 ± 0.22 vs.0.25 ± 0.23, p = 0.429). The cutoff value of the His(A)-SPP interval for successful cryoablation was 82 msec with a sensitivity of 0.67 and specificity of 0.71 (AUC: 0.739; 95%CI: 0.626-0.852; p < 0.0001). Three-dimensional mapping in all 8 patients showed that sites with the most delayed atrial activation and the last deflection of the fragmented SP potential within the Koch's triangle coincided with success-sites.

CONCLUSION

A longer His(A)-SPP interval and fractionated SP potential were characteristics of successful cryoablation for SP modification in slow-fast AVNRT.

The Relevance of Heart Rate Fluctuation When Evaluating Atrial Substrate Electrical Features in Catheter Ablation of Paroxysmal Atrial Fibrillation

Coronary sinus (CS) catheterization is critical during catheter ablation (CA) of atrial fibrillation (AF). However, the association of CS electrical activity with atrial substrate modification has been barely investigated and mostly limited to analyses during AF. In sinus rhythm (SR), atrial substrate modification is principally assessed at a global level through P-wave analysis. Cross-correlating CS electrograms (EGMs) and P-waves’ features could potentiate the understanding of AF mechanisms. Five-minute surface lead II and bipolar CS recordings before, during, and after CA were acquired from 40 paroxysmal AF patients. Features related to duration, amplitude, and heart-rate variability of atrial activations were evaluated. Heart-rate adjustment (HRA) was applied. Correlations between each P-wave and CS local activation wave (LAW) feature were computed with cross-quadratic sample entropy (CQSE), Pearson correlation (PC), and linear regression (LR) with 10-fold cross-validation. The effect of CA between different ablation steps was compared with PC. Linear correlations: poor to mediocre before HRA for analysis at each P-wave/LAW (PC: max. +18.36%, p = 0.0017, LR: max. +5.33%, p = 0.0002) and comparison between two ablation steps (max. +54.07%, p = 0.0205). HRA significantly enhanced these relationships, especially in duration (P-wave/LAW: +43.82% to +69.91%, p < 0.0001 for PC and +18.97% to +47.25%, p < 0.0001 for LR, CA effect: +53.90% to +85.72%, p < 0.0210). CQSE reported negligent correlations (0.6−1.2). Direct analysis of CS features is unreliable to evaluate atrial substrate modification due to CA. HRA substantially solves this problem, potentiating correlation with P-wave features. Hence, its application is highly recommended.

Coronary Sinus Diameter as a Potential Marker of Right Ventricle Impairment

The aim of this study was to assess the influence of the parameters of the coronary sinus (CS) on the parameters that describe the function of the right ventricle (RV), which were calculated using cardiac computed tomography. Methods: A CT scan of the heart was performed on 150 patients due to suspicion of coronary artery disease using a Siemens Somatom Force (2 × 192 × 0.6) and a syngo.via workstation. The “CT coronary” and in some cases the generic presets were used to measure the CS ostium in millimeters (mm). The functional measurements of right heart ventricles were examined using the “CT cardiac function” automatic function on a 256 × 256 matrix. Results: The average diameter of the CS ostium was 16.29 ± 4.37 mm. In the group with RV impairment, it was 16.56 ± 4.76, whereas in the group with normal values of the RV, it was 15.98 ± 3.88 mm, p = 0.4199. The average angle of the entrance of the CS into the right atrium was 107.25° ± 9.68°. In the group with an RV impairment, it was 105.91° ± 9.22°, while in the patients with normal values of the RV, it was 108.82° ± 10.04°; p = 0.0682. A multiple regression showed that end systolic volume (p = 0.0017) and stroke volume (p = 0.0144) are important predictors of the CS ostium. Conclusions: Some relationships were found between the CS and the selected parameters that describe the function of the RV. This may suggest a role for the CS as a right ventricular buffer, which could potentially be treated as a marker of an RV impairment.