Surgical technique and the mechanism of atrial tachycardia late after open heart surgery

Atypical Atrial Flutter: Electrophysiological Characterization and Effective Catheter Ablation

Atrial flutter (AFL), defined as macro-re-entrant atrial tachycardia, is associated with debilitating symptoms, stroke, heart failure, and increased mortality. AFL is classified into typical, or cavotricuspid isthmus (CTI)-dependent, and atypical, or non-CTI-dependent. Atypical AFL is a heterogenous group of re-entrant atrial tachycardias that most commonly occur in patients with prior heart surgery or catheter ablation. The ECG pattern is poorly predictive of circuit anatomy but may still provide mechanistic insight. AFL is difficult to manage medically and catheter ablation is the preferred treatment for most patients. Recent progress in technology and clinical electrophysiology has led to detailed characterization of re-entry circuits and effective ablation strategies. Combined activation and entrainment mapping are key to identifying the re-entry circuit. The presence of a slow-conducting isthmus, localized re-entry, dual-loop re-entry or bystander loops may lead to misleading activation maps but can be identified by electrogram examination and entrainment mapping. In the occasional patient without inducible AFL, substrate mapping in sinus rhythm may be a viable strategy. Long-term ablation success requires the creation of a transmural continuous lesion across a critical component of the re-entry circuit. Procedural endpoints include bidirectional conduction block across linear lesions and non-inducibility of atrial tachycardia. The present review discusses the epidemiology, mechanisms, ECG characteristics, electrophysiological characterization, and catheter ablation of atypical AFL.

Charge density mapping demonstrates superiority in catheter ablation of post-surgical atrial tachycardias

Introduction

Atrial tachycardia (AT) frequently occurs after cardiac surgery or surgical ablation procedures. The novel charge density-based mapping system (CDM) provides global chamber mapping and can detect crucial pathways of conduction; therefore, it has potential added value in catheter ablation (CA) of post-surgical ATs. We aimed to test the hypothesis that CDM-guided CA procedures are safe, feasible, and may improve outcome compared to conventional sequential 3D mapping (CARTO)-based CA.

Methods and results

Consecutive patients undergoing CA for post-surgical AT guided by CDM or CARTO were enrolled. Procedural safety and efficiency were analyzed. Acute success, one-year outcome was assessed. A total of 35 patients (mean age 60.8 ± 10.6 years, 42.9% female) underwent CA of AT using CDM (n = 20) and CARTO (n = 15). A total of 61 ATs were mapped (35 in CDM and 26 in CARTO group). Four patients had focal ATs, 22 macro re-entrant, and 8 patients had ATs with both mechanisms. No differences were found in procedural complication (CDM 3 vs. CARTO 1 patient, p = 0.61). There were no differences in procedure duration (185.9 vs. 147.9 min, p = 0.09), fluoroscopy dose (165.0 vs. 155.0 mGy, p = 0.31), RF application number (28.0 vs. 18.0, p = 0.17) or duration (1,251.5 vs. 1,060.0 s, p = 0.54). Acute success was 95.0% in CDM and 73.3% in CARTO group (p = 0.14). Cumulative AT recurrence rates were lower in CDM group compared to CARTO group (10.0% vs. 46.7%, p = 0.02).

Conclusions

The CDM system is feasible. Our data suggest that patients treated with CDM-guided CA developed fewer AT recurrences as compared to CARTO-guided procedures.

High density mapping of complex atrial tachycardia in patients after cardiac surgery

To provide an overview of the current application of high-density mapping (HDM) in the mechanism of complex atrial tachycardias (ATs). Complex ATs are frequently scar-related, after history of previous cardiac surgery and large scars. These scar-related ATs are difficult to manage medically and frequently recur after electrical cardioversion. HDM technologies have enabled rigorous elucidation of AT mechanisms in patients post cardiac surgery. This article showed the application of HDM technology in complex ATs from the mechanisms of complex ATs, the development of HDM technology, and the identification of scars or critical isthmus from HDM. HDM-guided approach is highly effective for identifying the ATs mechanism and critical isthmus.

Pathophysiology of Atypical Atrial Flutters

Atypical atrial flutters are complex supraventricular arrhythmias that share different pathophysiological aspects in common. In most cases, the arrhythmogenic substrate is essentially embodied by slow-conducting areas eliciting re-entrant circuits. Although atrial scarring seems to promote slow conduction, these arrhythmias may occur even in the absence of structural heart disease. To set out the ablation strategy in this setting, three-dimensional mapping systems have proved invaluable over the last decades, helping the cardiac electrophysiologist understand the electrophysiological complexity of these circuits and easily identify critical areas amenable to effective catheter ablation.

Atypical Cases of Typical Atrial Flutter? A Case Study

Ablation of typical atrial flutter has a high safety and efficacy profile, but hidden pitfalls may be encountered. In some cases, a longer cycle length with isoelectric lines is associated with a different or more complex arrhythmogenic substrate, which may be missed if conduction block of the cavotricuspid isthmus is performed in the absence of the clinical arrhythmia. Prior surgery may have consistently modified the atrial substrate and complex or multiple arrhythmias associated with an isthmus-dependent circuit can be encountered. In these cases, electroanatomic mapping is useful to guide the procedure and plan an appropriate ablation strategy.

Procedural Feasibility and Long-Term Efficacy of Catheter Ablation of Atypical Atrial Flutters in a Wide Spectrum of Heart Diseases: An Updated Clinical Overview

Atypical atrial flutters (AAFL) are difficult-to-manage atrial arrhythmias, yet potentially amenable to effective radiofrequency catheter ablation (CA). However, data on CA feasibility are only sparingly reported in the literature in different clinical settings, such as AAFL related to surgical correction of congenital heart disease. The aim of this review was to provide an overview of the clinical settings in which AAFL may occur to help the cardiac electrophysiologist in the prediction of the tachycardia circuit location before CA. Moreover, the role and proper implementation of cutting-edge technologies in this setting were investigated as well as which procedural and clinical factors are associated with long-term failure to maintain sinus rhythm (SR) to find out which patients may, or may not, benefit from this procedure. Not only different surgical and non-surgical scenarios are associated with peculiar anatomical location of AAFL, but we also found that CA of AAFL is generally feasible. The success rate may be as low as 50% in surgically corrected congenital heart disease (CHD) patients but up to about 90% on average after pulmonary vein isolation (PVI) or in patients without structural heart disease. Over the years, the progressive implementation of three-dimensional mapping systems and high-density mapping tools has also proved helpful for ablation of these macro-reentrant circuits. However, the long-term maintenance of SR may still be suboptimal due to the progressive electroanatomic atrial remodeling occurring after cardiac surgery or other interventional procedures, thus limiting the likelihood of successful ablation in specific clinical settings.

Is prophylactic ablation of the cavotricuspid and peri-incisional isthmus justified in patients with postoperative atrial flutter after right atriotomy?

BACKGROUND

The two most common postoperative atrial flutter (AFL) circuits after right atriotomy are the cavotricuspid isthmus (CTI) dependent and the lateral, peri-incisional. We investigated whether radiofrequency ablation (RFA) of both circuits results in more favorable long-term outcomes.

METHODS

Single-center retrospective cohort study of consecutive patients who underwent RFA of AFL after open-heart surgery. The effect of surgery type and RFA strategy on AFL recurrence was evaluated.

RESULTS

One hundred and forty-two patients (mean age 64.5 ± 12.7 years, 65.% male) were enrolled. Patients with right atrial (RA) flutter (n=124) were divided into two groups based on the index RFA procedure: only one RA circuit was ablated (Group 1, n= 84, 67.7%) or both the CTI and the peri-incisional circuit ablated (Group 2, n= 40, 32.3%). The previous open-heart surgery was categorized based on the extension of the RA incision: limited (Type A) or extended (Type B) atriotomy. After a mean follow-up of 36±28 months, flutter recurrence was not different among patients with limited RA atriotomy (25% vs. 22% in Group 1A and 2A, respectively, p=1.0). However, after type B surgery, ablation of both AFL circuits was associated with a reduced recurrence rate (63% vs. 26% in Group 1B and 2B, respectively, p=0.002).

CONCLUSIONS

In patients with postoperative RA flutter after extended right atriotomy, ablation of both the CTI and the peri-incisional isthmus significantly reduces the AFL recurrence rate. Prophylactic ablation of both isthmi, even if not proven to support reentry, is reasonable in this population. Keywords This article is protected by copyright. All rights reserved.

Macro-reentrant atrial tachycardia after tricuspid or mitral valve surgery: is there difference in electrophysiological characteristics and effectiveness of catheter ablation?

Background

Macro-reentrant atrial tachycardias (MATs) are a common complication after cardiac valve surgery. The MAT types and the effectiveness of MAT ablation might differ after different valve surgery. Data comparing the electrophysiological characteristics and the ablation results of MAT post-tricuspid or mitral valve surgery are limited.

Methods

Forty-eight patients (29 males, age 56.1 ± 13.3 years) with MAT after valve surgery were assigned to tricuspid valve (TV) group (n = 18) and mitral valve (MV) group (n = 30). MATs were mapped and ablated guided by a three-dimensional navigation system. The one-year clinical effectiveness was compared in two groups.

Results

Nineteen MATs were documented in TV group, including 16 cavo-tricuspid isthmus (CTI)-dependent AFL and 3 other MATs at right atrial (RA) free wall, RA septum and left atrial (LA) roof. Thirty-nine MATs were identified in MV group, including15 CTI-dependent AFL, 8 RA free wall scar-related, 2 RA septum scar-related, 8 peri-mitral flutter, 3 LA roof-dependent, 2 LA anterior scar-related, and 1 right pulmonary vein-related MAT. Compared with TV group, MV group had significantly lower prevalence of CTI-dependent AFL (38.5% vs. 84.2%), higher prevalence of left atrial MAT (35.9 vs.5.3%) and higher proportion of patients with left atrial MAT (40 vs. 5.6%), P = 0.02, 0.01 and 0.01, respectively. The acute success rate of MAT ablation (100 vs. 93.3%) and the one-year freedom from atrial tachy-arrhythmias (72.2 vs. 76.5%) was comparable in TV and MV group. No predictor for recurrence was identified.

Conclusion

Although the types of MATs differed significantly in patients with prior TV or MV surgery, the acute and mid-term effectiveness of MAT ablation was comparable in two groups.

Trial registration: This study was registered as a part of EARLY-MYO-AF clinical trial at the website ClinicalTrials. gov (NCT04512222).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02368-w.

Prediction of Recurrent Atrial Tachyarrhythmia After Receiving Atrial Flutter Ablation in Patients With Prior Cardiac Surgery for Valvular Heart Disease

Background: Surgical scars cause an intra-atrial conduction delay and anatomical obstacles that facilitate the perpetuation of atrial flutter (AFL). This study aimed to investigate the outcome and predictor of recurrent atrial tachyarrhythmia after catheter ablation in patients with prior cardiac surgery for valvular heart disease (VHD) who presented with AFL.

Methods: Seventy-two patients with prior cardiac surgery for VHD who underwent AFL ablation were included. The patients were categorized into a typical AFL group (n = 45) and an atypical AFL group (n = 27). The endpoint was the recurrence of atrial tachyarrhythmia during follow-up. A multivariate analysis was performed to determine the predictor of recurrence.

Results: No significant difference was found in the recurrence rate of atrial tachyarrhythmia between the two groups. Patients with concomitant atrial fibrillation (AF) had a higher recurrence of typical AFL compared with those without AF (13 vs. 0%, P = 0.012). In subgroup analysis, typical AFL patients with concomitant AF had a higher incidence of recurrent atrial tachyarrhythmia than those without it (53 vs. 14%, P = 0.006). Regarding patients without AF, the typical AFL group had a lower recurrence rate of atrial tachyarrhythmia than the atypical AFL group (14 vs. 40%, P = 0.043). Multivariate analysis showed that chronic kidney disease (CKD) and left atrial diameter (LAD) were independent predictors of recurrence.

Conclusions: In our study cohort, concomitant AF was associated with recurrence of atrial tachyarrhythmia. CKD and LAD independently predicted recurrence after AFL ablation in patients who have undergone cardiac surgery for VHD.

Ripple mapping-guided atrial tachycardia ablation following open-heart surgery

Ripple mapping can make the visualization of activation conduction on a 3-dimensional voltage map and is useful tool for scar-related organized atrial tachycardia (AT). This study sought to assess the efficacy of ripple mapping for interpreting reentrant circuits and critical isthmus in postoperative ATs. 34 consecutive patients with a history of mitral valve surgery (mean age, 54.5 ± 12.4 years) underwent high density (HD) RM during ATs with CARTO3v4 CONFIDENSE system. The voltage activation threshold was determined by RM over a bipolar voltage map. The identification of underlying mechanisms and ablation setting was based on RM without reviewing activation mapping. A total of 41 ATs (35 spontaneous, 6 induced) were characterized. 39 reentry circuits were successfully mapped (cycle length, 256 ± 43 ms). Of the 41 ATs, 28 were confirmed by ripple mapping alone (68%), and 12 (29%) by ripple mapping and entrainment mapping. Of 12 ATs in the left atrium, 9 (75%) needed entrainment to confirm, compared with 5 (17.8%) in the right atrium. Primary endpoint after initial ablation set was achieved in 32 of the 34 patients (94.1%). Freedom from atrial arrhythmias was 79.4% after the follow-up of 12 ± 5 months. Of the seven patients with recurrence, three underwent the repeated catheter ablation. Ripple mapping precisely delineated reentrant circuits in post-cardiac surgery AT resulting in a high success rate of ablation. Entrainment maneuvers remain useful for elucidation of complex AT circuits.

Ablation of atrial tachycardia in the setting of prior mitral valve surgery

BACKGROUND

Data regarding catheter ablation of post-surgical atrial tachycardia occurring after mitral valve surgery are scarce. Through a search of the literature, this study aimed to assess the feasibility of catheter ablation and the characteristics of atrial arrhythmias ablated in these patients.

METHODS

Studies assessing the main procedure parameters and the electrophysiologic findings of the investigated atrial tachycardia were selected. The electrophysiologic mechanism (focal vs. re-entrant arrhythmias), site of arrhythmia origin (left atrium vs. right atrium) and their anatomic correlation with specific surgical access and/or prior Cox-Maze IV procedure were all addressed.

RESULTS

Eleven studies including 206 patients undergoing catheter ablation of 297 post-surgical arrhythmia morphologies occurring after mitral valve surgery were considered. Major complications were observed in 2 patients only (0.9%). Restoration of sinus rhythm was achieved in 96% of patients. Macro-reentrant arrhythmia was mostly observed (90.4%) with a non-negligible proportion of focal arrhythmia (9.6%). Left-sided arrhythmia was common (54.4%,) but cavotricuspid isthmus-dependent arrhythmia was frequently reported (33%). Although specific atriotomies showed trends towards peculiar locations of the investigated arrhythmia, Cox-Maze IV procedure was the only independent predictor for left-sided arrhythmia (OR=17.3; 95% CI 7.2-41.2; P<0.0001).

CONCLUSIONS

Catheter ablation of post-surgical arrhythmia occurring after mitral valve surgery is feasible, and, in this setting, the vast majority of the arrhythmia morphologies are based on macro-reentry and in about one third of cases show cavotricuspid isthmus-dependent arrhythmia. Prior Cox-Maze-IV associated with mitral valve surgery is an independent predictor of left-sided arrhythmia possibly due to non-transmural surgical lesions.

Successful removal of a circular mapping catheter which perforated the pulmonary vein during cryoballoon ablation by lateral thoracotomy: a case report

Background

Serious complications may occur during cryoballoon ablation (CBA). However, pulmonary vein (PV) perforation by a circular mapping catheter and the strategy for removing the catheter remain poorly understood.

Case summary

A 40-year-old male presented with palpitations 2 years ago and was diagnosed with paroxysmal atrial fibrillation 5 months ago. He underwent CBA for paroxysmal atrial fibrillation. After isolation of the left PV, a circular mapping catheter was advanced in the right inferior pulmonary vein (RIPV), and single freeze was performed. After isolation of the PV, the catheter tip was immobile and could not be withdrawn with significant resistance. Computed tomography showed that the catheter tip perforated the posterior basal vein (V10) of the RIPV and remained in the right lower lobe, along with intrapulmonary haemorrhage. The patient underwent surgery via right lateral thoracotomy to remove the catheter. The RIPV was peeled to the periphery to expose the V10. The catheter perforated the vessel wall in the middle of the V10 and entered the pulmonary parenchyma. A microincision on the lung parenchyma covering the surface of the catheter tip was performed, and the circular distal portion of the catheter was cut. The entire catheter (i.e. shaft and proximal portion) was successfully removed from the transseptal catheter.

Discussion

Surgical approach was performed for the management of PV perforation caused by a circular mapping catheter. This case may assist in troubleshooting and problem-solving in case such an event occurs again during procedures in the future.

Different characteristics of postoperative atrial tachyarrhythmias between congenital and non-congenital heart disease

PURPOSE

The chance of encountering tachyarrhythmias has been increasing in adult congenital heart disease (CHD) patients with previous open-heart surgery, along with the improvement of their longevity. However, the characteristics of these arrhythmias remain to be elucidated.

METHODS

We examined the characteristics of atrial tachyarrhythmias (ATs) in 26 consecutive CHD patients (M/F 17/9) referred for catheter ablation and compared them with 16 non-CHD patients with cardiac surgery (M/F 11/5).

RESULTS

The CHD group was younger and had a longer period from cardiac surgery until the occurrence of ATs compared with the non-CHD group (44.8 ± 19.5 vs. 67.6 ± 12.5 years old, and 23.3 ± 13.2 vs. 6.3 ± 4.9 years, respectively, both P < 0.05). Multiple ATs were equally induced in both groups, 12 in CHD (46.1%) and 5 in non-CHD (31.3%). Although the prevalence of macro-reentrant ATs (cavo-tricuspid isthmus-dependent atrial flutter (AFL) or intra-atrial reentrant tachycardia (IART)) was comparable, the mechanisms were different between the 2 groups (AFL and IART), 34% and 27% in CHD and 71% and 24% in non-CHD, respectively. Furthermore, focal AT (FAT) was noted in 9 patients (34.6%) in CHD but none in non-CHD (P < 0.05). Electroanatomical mapping showed that the surface area and low-voltage area (LVA) of the right atrium were significantly larger in CHD than in non-CHD (197.1 ± 56.4 vs. 132.4 ± 41.2 cm², and 40.8 ± 33.3 vs. 13.6 ± 9.0 cm², respectively, both P < 0.05). Ten out of 14 FATs (71.4%) were highly associated with LVA, especially near the crista terminalis.

CONCLUSIONS

The development of ATs in CHD patients could be associated with large atrial remodeling, resulting in complicated ATs.

Atrial Tachycardias and Atypical Atrial Flutters: Mechanisms and Approaches to Ablation

Atrial tachycardias (ATs) may be classified into three broad categories: focal ATs, macroreentry and localised reentry – also known as ‘microreentry’. Features that distinguish these AT mechanisms include electrogram characteristics, responses to entrainment and pharmacological sensitivities. Focal ATs may occur in structurally normal hearts but can also occur in patients with structural heart disease. These typically arise from preferential sites such as the valve annuli, crista terminalis and pulmonary veins. Macro-reentrant ATs occur in the setting of atrial fibrosis, often after prior catheter ablation or post atriotomy, but also de novo in patients with atrial myopathy. High-resolution mapping techniques have defined details of macro-reentrant circuits, including zones of conduction block, scar and slow conduction. Localised reentry occurs in the setting of diseased atrial myocardium that supports very slow conduction. A characteristic feature of localised reentry is highly fractionated, low-amplitude electrograms that encompass most of the tachycardia cycle length over a small diameter. Advances in understanding the mechanisms of ATs and their signature electrogram characteristics have improved the efficacy and efficiency of catheter ablation.

Focal Atrial Tachycardia Arising from the Inferior Vena Cava

The inferior vena cava (IVC) is a rare site of focal atrial tachycardia (AT). Here, we report a 20-year-old woman who underwent catheter ablation for anti-arrhythmic drug-resistant AT originating from the IVC. She had undergone open-heart surgery for patch closure of an atrial septal defect 17 years previously and permanent pacemaker implantation for sinus node dysfunction 6 years previously. The AT focus was at the anterolateral aspect of the IVC-right atrial junction, and it was successfully ablated under three-dimensional electroanatomical-mapping guidance. We suspect that the mechanism of this tachycardia was associated with previous IVC cannulation for open-heart surgery.

Isolated Congenital Right Atrial Aneurysm: Monitoring Parameters for Asymptomatic Patients

Isolated congenital right atrial aneurysm is rare. Indications for surgery in asymptomatic patients with moderate-size right atria remain controversial. Evidence in support of medical management and timing of prophylactic surgery is reviewed. We propose the use of three echocardiographic indices to help identify inappropriate atrial growth and facilitate surgical decision-making.

Atrial tachycardias occurring late after open heart surgery

Atrial tachycardias are common after open heart surgery. Most commonly these are macro-reentrant including cavotricuspid isthmus dependent atrial flutter, incisional right atrial flutter and left atrial flutter. Focal atrial tachycardias occur less frequently. The specific type of atrial tachycardia highly depends on the type of surgical incision. Catheter ablation can be very effective, however requires a thorough understanding of anatomy and surgical technique.

Long-Term Outcome After Ablation of Right Atrial Tachyarrhythmias After the Surgical Repair of Congenital and Acquired Heart Disease

Atrial myopathy, atriotomies, and fibrotic scars are the pathophysiological substrate of lines of conduction block, promoting atrial macroreentry. The aim of this study was to determine the acute and long-term outcome of radiofrequency catheter ablation (RFCA) for right atrial tachyarrhythmia (AT) in adults after cardiac surgery for congenital heart disease (CHD) and acquired heart disease (AHD) and predictors of these outcomes. Clinical records of adults after surgery for heart disease undergoing RFCA of right-sided AT were analyzed retrospectively. Multivariate analyses identified clinical and procedural factors predicting acute and long-term outcomes. A total of 372 patients (69% men; age 61 ± 15 years) after surgical repair of CHD (n = 111) or AHD (n = 261) were studied. Cavotricuspid isthmus-dependent atrial flutter (CTI-AFL) was observed in 300 patients and non-CTI-AFL in 72 patients. Ablation was successful in 349 cases (94%). During a mean follow-up of 51 ± 30 months, recurrences were observed in 24.5% of patients. Multivariate analysis showed that non-CTI-AFL (hazard ratio [HR] 1.78, 95% confidence interval [CI] 1.1 to 2.9) and CHD (HR 1.75, 95% CI 1.07 to 2.9) were independent predictors of long-term recurrences. Multivariate analysis showed that female gender (HR 2.29, 95% CI 1.6 to 3.3), surgery for AHD (HR 95% 2.31, 95% CI 1.5 to 3.7), and left atrial dilatation (HR 2.1, 95% CI 1.3 to 3.2) were independent predictors of long-term atrial fibrillation. In conclusion, RFCA of right-sided AT after cardiac surgery is associated with high acute success rates and significant long-term recurrences. Non-CTI-dependent AFL and surgery for CHD are at higher risk of recurrence. Atrial fibrillation is common during follow-up, particularly in patients with AHD and enlarged left atrium.