Contact-force-guided vs. contact-force-blinded catheter ablation of typical atrial flutter: a prospective study

Local impedance and contact force guidance to predict successful cavotricuspid isthmus ablation with a zero-fluoroscopy approach

Introduction

A new technology capable of monitoring local impedance (LI) and contact force (CF) has recently been developed. At the same time, there is growing concern regarding catheter ablation performed under fluoroscopy guidance, due to its harmful effects for both patients and practitioners. The aim of this study was to assess the safety and effectiveness of zero-fluoroscopy cavotricuspid isthmus (CTI) ablation monitoring LI drop and CF as well as to elucidate if these parameters can predict successful radiofrequency (RF) applications in CTI ablation.

Methods

We conducted a prospective observational study recruiting 50 consecutive patients who underwent CTI ablation. A zero-fluoroscopy approach guided by the combination of LI drop and CF was performed. In each RF application, CF and LI drop were monitored. A 6-month follow-up visit was scheduled to assess recurrences.

Results

A total of 767 first-pass RF applications were evaluated in 50 patients. First-pass effective RF applications were associated with greater LI drops: absolute LI drops (30.05 ± 6.23 Ω vs. 25.01 ± 5.95 Ω), p = 0.004) and relative LI drops (-23.3 ± 4.9% vs. -18.3 ± 5.6%, p = 0.0005). RF applications with a CF between 5 and 15 grams achieved a higher LI drop compared to those with a CF below 5 grams (29.4 ± 8.76 Ω vs. 24.8 ± 8.18 Ω, p < 0.0003). However, there were no significant differences in LI drop between RF applications with a CF between 5 and 15 grams and those with a CF beyond 15 grams (29.4 ± 8.76 Ω vs. 31.2 ± 9.81 Ω, p = 0.19). CF by itself, without considering LI drop, did not predict effective RF applications (12.3 ± 7.54 g vs. 11.18 ± 5.18 g, p = 0.545). Successful CTI ablation guided by a zero-fluoroscopy approach was achieved in all patients. Only one patient experienced a recurrence during the 6-month follow-up.

Conclusions

LI drop (absolute and relative values) appears to be a good predictor of successful RF applications to achieve CTI conduction block. The optimal CF to achieve a good LI drop is between 5 and 15 g. A zero-fluoroscopy approach guided by LI and CF was feasible, effective, and safe.

Lesion size index-guided cavotricuspid isthmus linear ablation

BACKGROUND

The lesion size index (LSI) predicts radiofrequency (RF) ablation lesion size and is an established parameter for pulmonary vein isolation. However, the effectiveness and safety of LSI for cavotricuspid isthmus (CTI) linear ablation remain unclear.

METHODS

This single-center retrospective study included 50 of patients (67 ± 10 years, 68% male) who underwent de novo CTI linear ablation between July 2020 and December 2020. The LSI target was set at 5.0 and 4.0 for the anterior ^2/3 and posterior ^1/3 segments, respectively. Acute procedural parameters of ablation were evaluated.

RESULTS

Acute bidirectional CTI block was achieved in all patients with an RF application time of 4.0 min (3.1-5.0 min), RF application number of 15 ± 7, and length of CTI of 36.9 ± 9.3 mm. First-pass bidirectional conduction block of the CTI was achieved in 39/50 (78%) patients. No major complications were observed. The contact force (CF) per application was significantly lower in the gap tag group than in the non-gap tag group (7 g [7-8 g] vs. 10 g [7-12 g], P = 0.0284).

CONCLUSIONS

LSI-guided CTI linear ablation is an effective and safe treatment approach. CF affects gap formation, even when the target LSI is the same.

Cavotricuspid isthmus ablation for atrial flutter guided by contact force related parameters: A systematic review and meta-analysis

Background

Contact force (CF) and related parameters have been evaluated as an effective guide mark for pulmonary vein isolation, yet not for linear ablation of the cavotricuspid isthmus (CTI) dependent atrial flutter (AFL). We thus studied the efficacy and safety of CF related parameter-guided ablation for CTI-AFL.

Methods

Systematic search was performed on databases involving PubMed, EMbase, Cochrane Library and Web of Science (through June 2022). Original articles comparing CF related parameter-guided ablation and conventional parameter-guided ablation for CTI-AFL were included. One-by-one elimination, subgroup analysis and meta-regression were used for heterogeneity test between studies.

Results

Ten studies reporting on 761 patients were identified after screening with inclusion and exclusion criteria. Radiofrequency (RF) duration was significantly shorter in CF related parameter-guided group (p = 0.01), while procedural time (p = 0.13) and fluoroscopy time (p = 0.07) were no significant difference between two groups. CF related parameter-guided group had less RF lesions (p = 0.0003) and greater CF of catheter-tissue (p = 0.0002). Touch-up needed after first ablation line was less in CF related parameter-guided group (p = 0.004). In addition, there were no statistical significance between two groups on acute conduction recovery rates (p = 0.25), recurrence rates (p = 0.92), and complication rates (p = 0.80). Meta-regression analysis revealed no specific covariate as an influencing factor for above results (p > 0.10).

Conclusion

CF related parameters guidance improves the efficiency of CTI ablation, with the better catheter-tissue contact, the lower RF duration and the comparable safety as compared with conventional method, but does not improve the acute success rate and long-term outcome.

Comparison between the novel diamond temp and the classical 8-mm tip ablation catheters in the setting of typical atrial flutter

PURPOSE

Radiofrequency (RF) catheter ablation is widely accepted as a first-line therapy for cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL). The novel DiamondTemp (DT) catheter with temperature feedback during RF ablation has been released recently on the market. The purpose of this study was to evaluate the impact of DiamondTemp (DT) technology on ablation efficiency during AFL.

METHODS

In this single-center study, 30 consecutive patients with typical AFL indicated to ablation of CTI were included. The first 15 patients underwent CTI ablation using 8-mm tip catheter, and the following 15 patients underwent temperature-controlled RF ablation using DT catheter. The endpoints were number and mean total duration of RF applications, mean temperature reached in the setting of CTI, procedural times, and fluoroscopy times.

RESULTS

There were no significant differences between the two groups concerning baseline characteristics. Mean duration of the each application (71.5 s ± 30.6 vs 12.4 s ± 13.2, p value < 0.001), mean total duration of RF applications (517,73 s ± 377,96 vs 112,8 s ± 43,58; p value < 0.001), procedural times (51.6 min ± 24.2 vs 38.6 ± 8.2; p = 0.03), and fluoroscopy times (16.2 min ± 10.2 vs 8 min ± 4.24; p = 0.005) were longer in the 8-mm ablation catheter group. Mean temperature measurements (51.9 °C ± 3.59 vs 56.7 °C ± 3.34, p value < 0.003) were as well lower in the 8-mm ablation catheter group.

CONCLUSIONS

Catheter ablation of CTI-dependent AFL by means of DT resulted in a significant reduction of total and single application RF delivery time, procedure, and fluoroscopy times.

A Soft Resistive Sensor with a Semicircular Cross-Sectional Channel for Soft Cardiac Catheter Ablation

The field of soft robotics has attracted the interest of the medical community due to the ability of soft elastic materials to traverse the abnormal environment of the human body. However, sensing in soft robotics has been challenging due to the sensitivity of soft sensors to various loading conditions and the nonlinear signal responses that can arise under extreme loads. Ideally, soft sensors should provide a linear response under a specific loading condition and provide a different response for other loading directions. With these specifications in mind, our team created a soft elastomeric sensor designed to provide force feedback during cardiac catheter ablation surgery. Analytical and computational methods were explored to define a relationship between resistance and applied force for a semicircular, liquid metal filled channel in the soft elastomeric sensor. Pouillet's Law is utilized to calculate the resistance based on the change in cross-sectional area resulting from various applied pressures. FEA simulations were created to simulate the deformation of the sensor under various loads. To confirm the validity of these simulations, the elastomer was modeled as a neo-Hookean material and the liquid metal was modeled as an incompressible fluid with negligible shear modulus under uniaxial compression. Results show a linearly proportional relationship between the resistance of the sensor and the application of a uniaxial force. Altering the direction of applied force results in a quadratic relationship between total resistance and the magnitude of force.

The use of a high-power (50 W), ablation index-guided protocol for ablation of the cavotricuspid isthmus

BACKGROUND

High-power (HP) ablation protocols are increasingly used for ablation procedures to shorten procedural times and improve short- and long-term success. The ablation index (AI) combines contact force, power settings, and ablation time. It can be used in combination with HP protocols to guide operators toward standardized lesions. The purpose of this study was to evaluate both a HP and AI-guided strategy for ablation of the cavotricuspid isthmus (CTI) in patients with typical atrial flutter (AFL).

METHODS

In this single-center study, consecutive patients with typical AFL (n = 52, mean age 68.7 ± 8.3 years, 21/52 [40.4%] female) underwent AI-guided HP radiofrequency (RF) ablation of the CTI. Ablation was performed with 50 W and AI target values of 550 with a maximum ablation duration of 25 seconds per lesion. Target interlesion distance was ≤6 mm. Ablation was performed with a 3.5 mm porous tip Smarttouch SF catheter.

RESULTS

Acute CTI block was achieved in 52 of 52 patients (100%), and first-pass conduction block was achieved in 41 of 52 patients (80.4%). Spontaneous reconduction after 30 minutes waiting time occurred in 1 of 52 (1.9%) patient. Average ablation time until CTI block was 3:51 ± 1:40; 2:33 ± 1:01 minutes of bonus ablation pulses were applied after CTI block. An audible steam pop was noted in one patient (1.9%). No major complications occurred. After a mean follow-up of 193.7 ± 152.2 days, no patient showed recurrence of typical AFL.

CONCLUSION

In this pilot study, AI-guided HP ablation of the CTI was fast, safe, and effective.

High-power short-duration radiofrequency ablation of typical atrial flutter

Background

High-power short-duration (HPSD) ablation has been explored for pulmonary vein isolation. Early data suggest similar efficacy with shorter procedure times and perhaps greater safety. Data are lacking on the use of this ablation strategy for other arrhythmias.

Objective

The purpose of this study was to evaluate the safety, efficacy, and clinical outcomes of HPSD ablation in patients with typical atrial flutter compared to those undergoing ablation with conventional settings.

Methods

Consecutive patients undergoing cavotricuspid isthmus (CTI) ablation using standard power settings were compared to those performed after transitioning to HPSD ablation. Demographics, procedural details, and ablation outcomes were prospectively collected. The primary endpoint was duration of radiofrequency energy delivery. Secondary endpoints were radiation duration and analgesia requirements.

Results

A total of 114 consecutive subjects undergoing CTI ablation (57 standard power, 57 HPSD) were included. HPSD ablation and electroanatomic mapping/contact force (EAM/CF) use were associated with 66% (95% confidence interval [CI] 58%–73%) and 50% (95% CI 37%–60%) shorter ablation times compared to standard power and not using EAM/CF, respectively. Patients in the HPSD group required 50 mcg less fentanyl relative to the standard ablation arm after adjusting for sex, age, and comorbidities (P = .048). At a median follow-up of 6 months, 4 patients (7%) in the standard arm had recurrence of atrial flutter, compared to none in HPSD group (P = .057).

Conclusion

HPSD is a safe and effective approach to CTI ablation. This strategy may reduce ablation time and analgesia requirements. Larger studies and longer follow-up are needed to further evaluate this strategy.

[Atrial Flutter: up-to-date Problem Evaluation with Clinical Positions]

The review provides current ideas about the etiology and prevalence of atrial flutter (AF), mechanism and substrate of arrhythmogenesis, and principles of clinical and electrophysiological classification of this arrhythmia. Methods for conservative and surgical treatments of AF, including their comparative aspect, are described in detail. The review presented recent data on efficacy and potential risks of different approaches to reversing the arrhythmia. The authors indicated a need for early diagnosis and strict control of the sinus rhythm in AF, which would help a successful intervention not only to completely cure the existing arrhythmia but also to prevent other heart rhythm disorders, primarily atrial fibrillation.