Radiofrequency ablation of anteroseptal, para-Hisian, and mid-septal accessory pathways using a simplified femoral approach

Comparison between cryotherapy and radiofrequency energy sources for parahisian accessory pathway percutaneous ablation

BACKGROUND

Catheter ablation of parahisian accessory pathways (PHAP) are challenging due to their proximity to the normal conduction system. Retrospective studies suggest that cryoablation has a better safety profile but a higher recurrence rate when compared to radiofrequency ablation (RFCA). The objective of this study was to compare the results of parahisian AP ablation performed by electrophysiologists with experience in both technologies.

METHODS

Prospective single-center, non-blinded and 1:1 model was used. Patients included had parahisian AP confirmed by an electrophysiological study and referred for radiofrequency or cryotherapy ablation according to current guidelines, under fluoroscopic guidance. No electroanatomic mapping was used.

RESULTS

A total of 30 patients (mean age of 25±9.4 years; 90% male) were enrolled between Oct/2018 to Feb/2020. Acute success rate between RFCA and CRYO were similar (93% vs. 87%, p = 0.54). A nonsignificant reduction in short-term recurrence rate for RFCA (14% vs. 30%, p = 0.3) and mechanical trauma (6% vs. 20%; p = 0.28) was observed. Long-term recurrence rate and event-free survival time were similar in both groups after 1-year follow-up (p = 0.286). No persistent complete AV block or conduction disturbance was also observed.

CONCLUSION

Considering the limitation of a small sample size and the lack of use of electroanatomic mapping for RFCA, the efficacy and safety profile of parahisian AP ablation with RFCA was not different from CRYO, when performed by experienced electrophysiologists. No cases of permanent complete AV block were reported with either energy modalities.

Trans-jugular approach for safe and successful cryoablation of para-Hisian/anterior-septal, anterior, and anterior-lateral accessory pathways in children

BACKGROUND

Cryoablation of APs localized near the atrioventricular (AV) junction is a well-established ablation strategy in children, and it has proved to be very safe. However, recurrence rates remain considerable for specific accessory pathway (AP) localizations. The aim of this retrospective study was to evaluate the efficacy and safety of a trans-jugular approach for cryoablation of right anterior, anterior-lateral, and anterior-septal APs in children, as compared to the conventional femoral approach.

METHODS

From June 2019 to November 2023, 24 consecutive patients (mean age 13.2 ± 4.6, 12 males (50% of total cohort)) with right anterior-lateral, anterior, and anterior-septal/para-Hisian APs underwent 3D non-fluoroscopic transcatheter cryoablation through the right jugular vein at our Institution. Ablation results were compared with 24 patients for whom a conventional trans-femoral approach was used.

RESULTS

Acute procedural success rate was 100% (n = 24/24), with a non-statistically significant difference as compared to the control group (100% vs. 83%, p = 0.1). During follow-up (1.1 years, interquartile range 0.6-1.3), one patient (4%) had a recurrence in the trans-jugular group, as opposed to eight (38%) in the control group (p = 0.006). No permanent complications occurred.

CONCLUSIONS

3D cryoablation of right anterior-lateral, anterior, and anterior-septal/para-Hisian APs in children using a trans-jugular approach is extremely effective and safe, resulting in higher chronic success rate compared to the conventional femoral approach.

Iatrogenic Atrioventricular Block

Iatrogenic atrioventricular (AV) block can occur in the context of cardiac surgery, percutaneous transcatheter, or electrophysiologic procedures. In cardiac surgery, patients undergoing aortic and/or mitral valve surgery are at the highest risk for developing perioperative AV block requiring permanent pacemaker implantation. Similarly, patients undergoing transcatheter aortic valve replacement are also at increased risk for developing AV block. Electrophysiologic procedures, including catheter ablation of AV nodal re-entrant tachycardia, septal accessory pathways, para-Hisian atrial tachycardia, or premature ventricular complexes, are also associated with risk of AV conduction system injury. In this article, we summarize the common causes for iatrogenic AV block, predictors for AV block, and general management considerations.

Miniseries 2-septal and paraseptal accessory pathways-part III: mid-paraseptal accessory pathways-revisiting bypass tracts crossing the pyramidal space

The mid-paraseptal region corresponds to the portion of the pyramidal space whose right atrial aspect is known as the triangle of Koch. The superior area of this mid-paraseptal region is also para-Hisian, and is close to the compact atrioventricular node and the His bundle. The inferior sector of the mid-paraseptal area is unrelated to the normal atrioventricular conduction pathways. It is, therefore, a safe zone in which, if necessary, to perform catheter ablation. The middle part of the mid-paraseptal zone may, however, in some patients, house components of the compact atrioventricular node. This suggests the need for adopting a prudent attitude when considering catheter ablation in this area. The inferior extensions of the atrioventricular node, which may represent the substrate for the slow atrioventricular nodal pathway, take their course through the middle, and even the inferior, sectors of the mid-paraseptal region. In this review, we contend that the middle and inferior areas of the mid-paraseptal region correspond to what, in the past, was labelled by most groups as the 'midseptal' zone. We describe the electrocardiographic patterns observed during pre-excitation and orthodromic reciprocating tachycardia in patients with pathways ablated in the middle or inferior sectors of the region. We discuss the modification of the ventriculo-atrial conduction times during tachycardia after the development of bundle branch block aberrancy. We conclude that the so-called 'intermediate septal' pathways, as described in the era of surgical ablation, were insufficiently characterized. They should not be considered the surrogate of the 'midseptal' pathways defined using endocardial catheter electrode mapping.

Iatrogenic Atrioventricular Block

Iatrogenic atrioventricular (AV) block can occur in the context of cardiac surgery, percutaneous transcatheter, or electrophysiologic procedures. In cardiac surgery, patients undergoing aortic and/or mitral valve surgery are at the highest risk for developing perioperative AV block requiring permanent pacemaker implantation. Similarly, patients undergoing transcatheter aortic valve replacement are also at increased risk for developing AV block. Electrophysiologic procedures, including catheter ablation of AV nodal re-entrant tachycardia, septal accessory pathways, para-Hisian atrial tachycardia, or premature ventricular complexes, are also associated with risk of AV conduction system injury. In this article, we summarize the common causes for iatrogenic AV block, predictors for AV block, and general management considerations.

Update on Etripamil Nasal Spray for the At-home Treatment of Acute Paroxysmal Supraventricular Tachycardia

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Low-energy ablation of anteroseptal accessory pathways in two dogs

In humans, accessory pathways (APs) in an anteroseptal and midseptal position are often challenging to ablate because of their close proximity with the conduction pathways of the atrioventricular junction. The use of low-energy ablation techniques can be useful to reduce the risk of permanently damaging the atrioventricular node and the His bundle. This report describes the use of low-energy radiofrequency catheter ablation to successfully and permanently ablate anteroseptal APs in two dogs with orthodromic atrioventricular reciprocating tachycardia. In the first dog, a transient first degree atrioventricular block persisted for 30 s after radiofrequency energy delivery. In the second dog, transient paroxysmal atrioventricular conduction block was observed during the procedure but resolved within 3 days. First degree atrioventricular block was again identified 2 months later. In conclusion, anteroseptal APs can be effectively treated by low-energy radiofrequency catheter ablation with minimal and transient damage to the atrioventricular junction.

Experimental, Pathologic, and Clinical Findings of Radiofrequency Catheter Ablation of Para-Hisian Region From the Right Ventricle in Dogs and Humans

Background—

Ablation of para-Hisian accessory pathway (AP) poses high risks of atrioventricular block. We developed a pacing technique to differentiate the near-field (NF) from far-field His activations to avoid the complication.

Methods and Results—

Three-dimensional mapping of the right ventricle was performed in 15 mongrel dogs and 23 patients with para-Hisian AP. Using different pacing outputs, the NF- and far-field His activation was identified on the ventricular aspect. Radiofrequency application was delivered at the NF His site in 8 (group 1) and the far-field His site in 7 dogs (group 2), followed by pathologic examination after 14 days. NF His activation was captured with 5 mA/1 ms in 10 and 10 mA/1 ms in 5 dogs. In group 1, radiofrequency delivery resulted in complete atrioventricular block in 3, right bundle branch block with HV (His-to-ventricular) interval prolongation in 1, and only right bundle branch block in 2 dogs, whereas no changes occurred in group 2. Pathologic examination in group-1 dogs showed complete or partial necrosis of the His bundle in 4 and complete necrosis of the right bundle branch in 5 dogs. In group 2, partial necrosis in the right bundle branch was found only in 1 dog. Using this pacing technique, the APs were 5.7±1.2 mm away from the His bundle located superiorly in 20 or inferiorly in 3 patients. All APs were successfully eliminated with 1 to 3 radiofrequency applications. No complications and recurrence occurred during a follow-up of 11.8±1.4 months.

Conclusions—

Differentiating the NF His from far-field His activations led to a high ablation success without atrioventricular block in para-Hisian AP patients.

Efficacy and safety of cryoablation of parahissian accessory pathways in children: a single institution study

BACKGROUND

Catheter cryoablation of supraventricular tachycardias involving the perinodal regions is considered to be a safer alternative compared to radiofrequency ablation. Limited information is available for efficacy, midterm outcomes, and complications regarding the ablation of parahissian accessory pathways (APs) in pediatric patients.

METHODS

A retrospective review of all pediatric patients who underwent cryoablation for treatment of a parahissian AP was performed.

RESULTS

Twenty-five patients (median age 13 years and weight 45.6 kg) underwent cryoablation of a parahissian AP. Median number of cryolesions applied was four (range: 3-6). Initial procedural success was achieved in 23 patients (23/25, 92%). Transient third-degree atrioventricular (AV) block was noted in two patients. There was no permanent AV block. Transient right bundle branch block (RBBB) was observed in one patient and permanent RBBB occurred in two patients. Of the patients successfully ablated with cryo, there was only one recurrence (1/23, 4.3%) over a follow-up of 17.5 months (range 6-34 months).

CONCLUSION

Cryoablation of parahissian APs is both safe and effective with a low risk of recurrence in pediatric patients.

Cryoablation of anteroseptal accessory pathways in children with limited fluoroscopy exposure

Due to its safety profile, cryoablation is used increasingly in pediatric patients, especially for septal arrhythmia substrates. Recent advances in electroanatomical-mapping technologies have resulted in a decrease or complete elimination of fluoroscopy exposure during catheter ablation procedures. The aim of this study was to assess the efficacy and safety of cryoablation of anteroseptal accessory pathways (APs) using electroanatomical-mapping system guidance with limited fluoroscopy exposure. A total of 24 patients underwent cryoablation of anteroseptal APs between July 2010 and April 2012. Cryomapping was performed with a 6 mm-tip catheter at -30 °C before the lesions were delivered. An 8 mm-tip catheter was used in one patient. The EnSite system (St. Jude Medical, St Paul, MN) was used in all procedures. The mean age was 11.9 ± 4.3 years. Acute success rate was 95.8 % (23 of 24). The mean procedure and cryoablation durations were 168 ± 58 min and 1,463 ± 525 s, respectively. Limited fluoroscopy was used only in 7 patients, and the mean fluoroscopy time was 1.7 ± 1.8 min (range 0.1-4 min) in these patients. Recurrence was noted in 2 patients (8.7 %) who underwent a second successful cryoablation procedure. The patient who underwent a failed attempt during the first procedure was successfully treated with a repeat procedure. The resultant long-term success rate was 100 % at a mean follow-up period of 14.2 ± 7.7 months. There were no complications except for transient atrioventricular block in one patient. Cryoablation of anteroseptal APs can be performed effectively and safely in children using a limited fluoroscopic approach with the help of electroanatomical-mapping systems.

[Invasive electrophysiology: complications, nightmares and their management]

Most minor side effects of ablation in the right atrium and right ventricle relate to femoral venous catheterization but there is a small risk of severe complications including atrioventricular (AV) block, damage of surrounding structures and thromboembolic events. Impairment of AV conduction can occur during ablation of atrioventricular re-entrant tachycardia, ablation of anteroseptal, mid-septal and parahisian accessory pathways, ablation of ectopic atrial tachycardia originating from the vicinity of the atrioventricular node and when ablating the septal isthmus for typical atrial flutter. Damage of the right coronary artery is a very rare complication after inferior isthmus ablation with high energy. The thromboembolic risk during and after cardioversion and ablation of atrial flutter is higher than previously recognized and anticoagulation therapy decreases this risk. The risk of perforation and tamponade during ablation in the right atrium and right ventricle is very low but particular caution is necessary in thin-walled structures such as the coronary sinus and the upper right ventricular outflow tract. Phrenic nerve injury can be avoided by pacing from the mapping electrode before application of radiofrequency energy at the right atrial free wall. Limitation of power output depending on the site of ablation and titration of energy application with continuous control of temperature and impedance should be considered to minimize the risk of complications.

Cryoablation:. Potentials and Pitfalls

The use of cryoablation in the electrophysiology lab provides some distinct advantages not seen with conventional radiofrequency ablation. Ice mapping allows a functional assessment of a putative ablation site prior to the formation of a permanent lesion. This provides a distinct advantage adjacent to the AV node for para-hisian pathways and difficult cases of AVNRT. Cryoablation also produces minimal endothelial disruption and thrombus formation and causes no collagen shrinkage. This is likely advantageous when ablation is required within venous structures. There is also mounting experimental evidence that cryoablation is safe adjacent to the arterial system, especially within the middle cardiac vein or distal coronary sinus. As the technology evolves and further iterations of the catheter proceed, the role for this new but well-established technology is likely to grow.

Radiofrequency catheter ablation of septal accessory pathways in the pediatric age group

Radiofrequency catheter ablation (RCA) of septal accessory pathways may be technically challenging in children due to the risk of inadvertent atrioventricular (AV) block in the setting of small cardiac dimensions. Outcomes were reviewed for all patients aged < or =19 years with manifest and concealed septal accessory pathways undergoing RCA since 1990 at a single institution. One hundred forty-five procedures were performed in 127 patients (mean age 11.6 years). The number of studies according to accessory pathway location were: anteroseptal (n = 36), midseptal (n = 20), mouth of coronary sinus (n = 40), middle cardiac vein (n = 6), right posteroseptal (n = 21), and left posteroseptal (n = 22). Ablation was deferred for 9 patients (6 anteroseptal and 3 midseptal) in favor of additional pharmacologic trials. Acute success rates for targeted accessory pathways were: anteroseptal (96%), midseptal (94%), mouth of coronary sinus (88%), middle cardiac vein (100%), right posteroseptal (100%), and left posteroseptal (96%). Recurrence rates during follow-up were: anteroseptal (14%), midseptal (12%), mouth of coronary sinus (3%), right posteroseptal (4%), and left posteroseptal (4%). Permanent second or third degree AV block occurred in 4 of 136 RCA attempts (3%), involving 2 anteroseptal and 2 midseptal pathways. In 3 of these 4 cases, a high probability of block was anticipated from prior ablation efforts, prompting pacemaker insertion before or in conjunction with RCA. Thus, in the pediatric age group, acute RCA success rates for septal accessory pathways can exceed 90%. The risks of AV block and accessory pathway recurrence are most relevant to anteroseptal and midseptal pathways. These data may be factored into patient selection and the decision whether to ablate.

Safety and efficacy of cryoablation of accessory pathways adjacent to the normal conduction system

Cryoablation of Septal Accessory Pathways.

INTRODUCTION

Catheter ablation has become a routine treatment for patients with Wolff-Parkinson-White syndrome because of its low risk and high efficacy; however, radiofrequency ablation in the septum close to the AV node or His bundle still carries a definite risk for AV block. Cryoenergy catheter ablation has recently become available. This technique has specific features, such as the ability to create reversible loss of function to predict the effects of ablation (ice mapping) and the adherence of the catheter tip to the endocardium with freezing, which avoids the risk for dislodgment. Both of these characteristics may minimize the risk of complications. The aim of this study was to analyze the effectiveness and safety of catheter cryoablation in 20 patients with para-Hisian or midseptal accessory pathways (AP).

METHODS AND RESULTS

Eleven patients with para-Hisian and 9 patients with midseptal AP underwent catheter cryoablation. Ice mapping at -30 degrees C was performed to ascertain the disappearance of AP conduction and the absence of impairment of AV nodal conduction. If the expected result was obtained, cryoablation was performed by lowering the temperature to -75 degrees C for 4 minutes in order to create a permanent lesion. Cryoablation was successful in all patients using a mean of 1.2 +/- 0.4 applications. Recurrences occurred in 4 patients (20%) who underwent a second successful cryoablation session. No complications were observed.

CONCLUSION

Cryoablation appears to be a safe and effective technique for ablation of APs close to the AV node or His bundle because of the ability to predict the acute effects of ablation with ice mapping before creation of an irreversible lesion.

Successful ablation of Hisian ectopy identified by a reversed His bundle activation sequence

Junctional ectopy or tachycardia have been mapped and ablated in the atrioventricular node or its posterior extensions. There is no report of Hisian ectopy convincingly demonstrated and then successfully treated by ablation. A 39-year-old man presented with a 9-year history of recurrent supraventricular ectopy refractory to medical treatment. Intracardiac mapping revealed that the ectopy originated from the His bundle, which was indicated by a reversed His bundle activation sequence during ectopy compared to that during sinus rhythm, while the right bundle branch potential was anterogradely activated. Low power RF energy delivered to the site of earliest activation completely abolished the ectopic activity without modification of Hisian or atrioventricular conduction. After a 12-month followup, the patient remains free of recurrence.

Outcomes after radiofrequency catheter ablation of atrial tachycardia

The purpose of this study was to evaluate the efficacy, safety, and clinical benefit of radiofrequency catheter ablation (RFCA) in a large series of patients with atrial tachycardia (AT). The determinants of success or failure of RFCA in AT remain unclear. We evaluated the results of radiofrequency ablation in 73 women and 32 men (mean age 48 +/- 19 years) with AT. Mapping techniques were based on identification of the earliest endocardial atrial electrogram recorded during AT. AT originated from the right atrium in 91 patients and from the left atrium in 14. The cardiac ventricles were dilated in 12 patients. AT ablation was successful in 80 patients (77%) regardless of the site of origin. Age, gender, rate of tachycardia, temperature achieved during application, or presence of tachycardiomyopathy were not significant determinants of acute success by univariate analysis. There was a significantly higher acute success rate of ablation in patients with paroxysmal (88%, 45 of 51) and permanent (71%, 30 of 42) forms than in patients with repetitive forms of AT (41%, 5 of 12) (p <0.005). The mean local endocardial electrogram time (relative-to-surface P-wave onset) was -47 +/- 17 ms at successful ablation sites and -29 +/- 21 ms at unsuccessful sites (p <0.03). Ablation was unsuccessful in 25 cases. Thus, RFCA of AT can be performed with a high acute success rate. Patients with repetitive forms and those with multifocal origin had a lower acute success rate. The highest incidence of recurrences was found in anterior right atrial foci.