Atrial Tachycardia Arising From the Crista Terminalis, Detailed Electrophysiological Features and Long-Term Ablation Outcomes

The Characteristics and Clinical Analysis of Lorenz Plot of Neonatal Atrial Tachycardia

BACKGROUND

Lorenz plot (LP) analysis enhances the accuracy of arrhythmia diagnosis and serves as an attractive diagnostic tool for patients with arrhythmias. We explored the utility of the LP in the classification of various types of neonatal atrial tachycardia and evaluated the treatment effects and prognosis.

METHODS

Ninety-six newborns with atrial tachycardia had their dynamic electrocardiograms and clinical data collected between January 2018 and June 2023. They were divided into different atrial tachycardia groups based on the morphological characteristics of the LP. The clinical features of the patients in each group were also analyzed.

RESULTS

Neonates were divided into multifocal (30%, 31.25%), parasystole (19%, 19.79%), and atrial premature beat-induced atrial tachycardia (47%, 48.96%) groups. It was demonstrated that the prevalence of cardiac structural abnormalities, viral infections, myocardial injury, and heart failure was significantly increased in the multifocal atrial tachycardia group.

CONCLUSIONS

The analysis of distinct LP patterns allowed for the identification and classification of neonatal atrial tachycardia, which could improve the diagnostic efficiency of neonatal atrial tachycardia and assist clinical physicians in making better management strategies based on the type of atrial tachycardia.

The role of the right atrial appendage and right atrium in post-radiofrequency ablation recurrence in different types of atrial fibrillation

AIM

To quantitatively evaluate the relationship between the anatomical parameters of the right atrium and the recurrence of atrial fibrillation (AF) after radiofrequency ablation, considering different types of AF, utilizing 256-slice spiral computed tomography (CT).

MATERIALS AND METHODS

A total of 297 patients with AF who underwent initial radiofrequency ablation were enrolled, divided into the paroxysmal atrial fibrillation (PaAF) group (n=230) and the persistent atrial fibrillation (PeAF) group (n=67). Subsequently, patients in each group were further stratified into recurrent and non-recurrent subgroups. In addition, 100 healthy outpatients were selected as the normal group. All patients underwent preoperative cardiac CT (CCT) examination. The volumes of the right atrium (RA), right atrial appendage (RAA), and left atrial (LA), RAA height, the length, short diameter, perimeter, and area of the RAA base, anteroposterior diameter of the RA, tricuspid annulus diameter, crista terminalis, and inferior vena cavotricuspid isthmus (CTI) on CCT images were measured.

RESULTS

In both the PaAF group and the PeAF group, except for the crista terminalis thickness, the other measured parameters were greater than those in the normal group, and recurrent patients exhibited larger RAA base, crista terminalis and LA volume. Recurrent patients with PeAF presented larger RAVI, while recurrent patients with PaAF did not. The short diameter of the RAA base was an independent predictor of recurrence in patients with PaAF (p=0.001), while the height of the RAA, thickness of the crista terminalis, and hypertension were independent predictors of recurrence in PeAF (p<0.05). The ROC curve was used to analysis the predictive model in PaAF and PeAF group, the corresponding sensitivity and specificity were 0.604 and 0.864 in PaAF group, respectively (AUC = 0.840, P=0.001), in PeAF group, the corresponding sensitivity and specificity were 0.967 and 0.892, respectively (AUC = 0.959, P=0.001). The short diameter of RAA base > 22.15 mm had the highest predictive value for recurrence in PaAF patients, with a sensitivity of 0.887, and a specificity of 0.520 (AUC: 0.743, p=0.001). The RAA height > 28.95 mm has the highest predictive value for recurrence in PeAF, with a sensitivity of 0.633, and a specificity of 0.865 (AUC: 0.816, p=0.001).

CONCLUSION

Recurrent patients both in the PaAF and PeAF groups demonstrated larger RAA base and RA structural parameters. Compared to patients with PaAF, recurrent patients with PeAF presented larger RA volume.

Ablation Strategies for Persistent Atrial Fibrillation: Beyond the Pulmonary Veins

Despite advances in ablative therapies, outcomes remain less favorable for persistent atrial fibrillation often due to presence of non-pulmonary vein triggers and abnormal atrial substrates. This review highlights advances in ablation technologies and notable scientific literature on clinical outcomes associated with pursuing adjunctive ablation targets and substrate modification during persistent atrial fibrillation ablation, while also highlighting notable future directions.

Prominent crista terminalis mimicking a right atrial mass: a systematic literature review and meta-analysis

The crista terminalis is an anatomical structure localized on the posterolateral wall of the right atrium (RA). We performed a systematic review of the literature and meta-analysis concerning cases of unusual prominent crista terminalis mimicking RA mass. Moreover, we described the differential diagnosis of cardiac masses with the use of echocardiography, computed tomography, and cardiac magnetic resonance (CMR). We also emphasize the potential importance of this structure in electrophysiological procedures, including its role in exaggerated arrhythmias. Prominent crista terminalis may be a potential obstacle during invasive cardiac procedures or catheter ablation target. In analyzed cases, the crista terminalis was often erroneously interpreted as pathologic and at first confused with a thrombus or tumor during transthoracic echocardiography examination. The correct final diagnoses were mostly made with used transesophageal echocardiography or CMR. The most important imaging findings suggestive of prominent crista terminalis rather than tumor were a similar echogenicity/intensity with adjacent myocardium, the location on posterolateral wall of the RA, the phasic change in size, and no enhancement after contrast injection. We describe up to date and detailed imaging features for the differential diagnostics of selected intracardiac masses using various imaging techniques, including multimodality cardiac imaging. Familiarity with the anatomy and the imaging findings of the prominent crista terminalis will reduce misdiagnosis and avoid additional tests and unwarranted clinical interventions, while in patients considered for invasive cardiac procedures it might increase their efficacy and safety.

Detailed analysis of tachycardia cycle length aids diagnosis of the mechanism and location of atrial tachycardias

AIMS

Although the mechanism of an atrial tachycardia (AT) can usually be elucidated using modern high-resolution mapping systems, it would be helpful if the AT mechanism and circuit could be predicted before initiating mapping.

OBJECTIVE

We examined if the information gathered from the cycle length (CL) of the tachycardia can help predict the AT-mechanism and its localization.

METHODS

One hundred and thirty-eight activation maps of ATs including eight focal-ATs, 94 macroreentrant-ATs, and 36 localized-ATs in 95 patients were retrospectively reviewed. Maximal CL (MCL) and minimal CL (mCL) over a minute period were measured via a decapolar catheter in the coronary sinus. CL-variation and beat-by-beat CL-alternation were examined. Additionally, the CL-respiration correlation was analysed by the RhythmiaTM system. : Both MCL and mCL were significantly shorter in macroreentrant-ATs [MCL = 288 (253-348) ms, P = 0.0001; mCL = 283 (243-341) ms, P = 0.0012], and also shorter in localized-ATs [MCL = 314 (261-349) ms, P = 0.0016; mCL = 295 (248-340) ms, P = 0.0047] compared to focal-ATs [MCL = 506 (421-555) ms, mCL = 427 (347-508) ms]. An absolute CL-variation (MCL-mCL) < 24 ms significantly differentiated re-entrant ATs from focal-ATs with a sensitivity = 96.9%, specificity = 100%, positive predictive value (PPV) = 100%, and negative predictive value (NPV) = 66.7%. The beat-by-beat CL-alternation was observed in 10/138 (7.2%), all of which showed the re-entrant mechanism, meaning that beat-by-beat CL-alternation was the strong sign of re-entrant mechanism (PPV = 100%). Although the CL-respiration correlation was observed in 28/138 (20.3%) of ATs, this was predominantly in right-atrium (RA)-ATs (24/41, 85.7%), rather than left atrium (LA)-ATs (4/97, 4.1%). A positive CL-respiration correlation highly predicted RA-ATs (PPV = 85.7%), and negative CL-respiration correlation probably suggested LA-ATs (NPV = 84.5%).

CONCLUSION

Detailed analysis of the tachycardia CL helps predict the AT-mechanism and the active AT chamber before an initial mapping.

A rare focal atrial tachycardia arising from the proximal middle cardiac vein: a case report

BACKGROUND

Focal atrial tachycardia (FAT) always originates from atrium specific sites and can be successfully cured by radiofrequency (RF) ablation. However, the middle cardiac vein (MCV) is a rare site of focal atrial tachycardia. Herein, we present a case of a 20-year-old young woman with FAT. Electrophysiological examination showed FAT arising from the proximal middle cardiac vein (pMCV), and successful RF ablation was applied with a low power and short-ablation.

CASE PRESENTATION

A 20-year-old woman with no structural heart disease suffered recurrent supraventricular tachycardia for 1 year. Physical examination, laboratory studies and the echocardiography results of this patient were normal. A 12-lead electrocardiogram (ECG) showed a narrow QRS and long RP tachycardia which was always triggered by a sinus rhythm. The patient underwent an electrophysiological study and found the earliest activation was in the proximal MCV (pMCV). After a low power and short-ablation, AT was terminated and noninducible by programmed pacing with or without isoproterenol infusion.

CONCLUSION

This case presented a rare case of FAT arising from the pMCV. We demonstrate that low power and short-ablation are effective in AT arising from specific areas such as the coronary sinus ostium and pMCV.

Role of non-pulmonary vein triggers in persistent atrial fibrillation

Pulmonary vein isolation is an well-established treatment strategy for atrial fibrillation (AF), and it is especially effective for patients with paroxysmal AF. However, the success rate is limited for patients with persistent AF, because non-pulmonary vein triggers which increase AF recurrence are frequently found in these patients. The major non-pulmonary vein triggers are from the left atrial posterior wall, left atrial appendage, ligament of Marshall, coronary sinus, superior vena cava, and crista terminalis, but other atrial sites can also generate AF triggers. All these sites have been known to contain atrial myocytes with potential arrhythmogenic electrical activity. The prevalence and clinical characteristics of these non-pulmonary vein triggers are well studied; however, the clinical outcome of catheter ablation for persistent AF is still unclear. Here, we reviewed the current ablation strategies for persistent AF and the clinical implications of major non-pulmonary vein triggers.

Echocardiographic evaluation of the right atrial size and function: Relevance for clinical practice

Right atrial (RA) structural and functional evaluations have recently emerged as powerful biomarkers for adverse events in various cardiovascular conditions. Quantitative analysis of the right atrium, usually performed with volume changes or speckle-tracking echocardiography (STE), has markedly changed our understanding of RA function and remodeling. Knowledge of reference echocardiographic values and measurement methods of RA volumes and myocardial function is a prerequisite to introduce RA quantitation in the clinical routine. This review describes the methodology, benefits and pitfalls of measuring RA size and function by echocardiography based on the current understanding of right atrial anatomy and physiological function and provides the current knowledge of right atrial function in related cardiac diseases.

Three-dimensional functional anatomy of the human sinoatrial node for epicardial and endocardial mapping and ablation

The sinoatrial node (SAN) is the primary pacemaker of the human heart. It is a single, elongated, 3-dimensional (3D) intramural fibrotic structure located at the junction of the superior vena cava intercaval region bordering the crista terminalis (CT). SAN activation originates in the intranodal pacemakers and is conducted to the atria through 1 or more discrete sinoatrial conduction pathways. The complexity of the 3D SAN pacemaker structure and intramural conduction are underappreciated during clinical multielectrode mapping and ablation procedures of SAN and atrial arrhythmias. In fact, defining and targeting SAN is extremely challenging because, even during sinus rhythm, surface-only multielectrode mapping may not define the leading pacemaker sites in intramural SAN but instead misinterpret them as epicardial or endocardial exit sites through sinoatrial conduction pathways. These SAN exit sites may be distributed up to 50 mm along the CT beyond the ∼20-mm-long anatomic SAN structure. Moreover, because SAN reentrant tachycardia beats may exit through the same sinoatrial conduction pathway as during sinus rhythm, many SAN arrhythmias are underdiagnosed. Misinterpretation of arrhythmia sources and/or mechanisms (eg, enhanced automaticity, intranodal vs CT reentry) limits diagnosis and success of catheter ablation treatments for poorly understood SAN arrhythmias. The aim of this review is to provide a state-of-the-art overview of the 3D structure and function of the human SAN complex, mechanisms of SAN arrhythmias and available approaches for electrophysiological mapping, 3D structural imaging, pharmacologic interventions, and ablation to improve diagnosis and mechanistic treatment of SAN and atrial arrhythmias.

[Focal atrial tachycardias: diagnostics and therapy]

In this article, typical characteristics of focal atrial tachycardias are described and a systematic approach regarding diagnostics and treatment options in the field of invasive cardiac electrophysiology (EP) is presented. Subjects of this article include the definition of focal atrial tachycardias, knowledge about localizing the origin of such, and guidance on how to approach an invasive EP study (e.g., administration of medication during the EP study to provoke tachycardias). Further, descriptions will be found on how to localize the origin of focal atrial tachycardias with the help of the 12-lead ECG and invasive three-dimensional mapping to successfully treat focal atrial tachycardias with catheter ablation.

Image Integration Using Intracardiac Echography and Three-dimensional Reconstruction for Mapping and Ablation of Atrial and Ventricular Arrhythmias

This article reviews the basis for image integration of intracardiac echocardiography (ICE) with three-dimensional electroanatomic mapping systems and preprocedural cardiac imaging modalities to enhance anatomic understanding and improve guidance for atrial and ventricular ablation procedures. It discusses the technical aspects of ICE-based integration and the clinical evidence for its use. In addition, it presents the current technical limitations and future directions for this technology. This article also includes figures and videos of clinical representative arrhythmia cases where the use of ICE is key to a safe and successful outcome.

Structural and Functional Properties of Subsidiary Atrial Pacemakers in a Goat Model of Sinus Node Disease

Background

The sinoatrial/sinus node (SAN) is the primary pacemaker of the heart. In humans, SAN is surrounded by the paranodal area (PNA). Although the PNA function remains debated, it is thought to act as a subsidiary atrial pacemaker (SAP) tissue and become the dominant pacemaker in the setting of sinus node disease (SND). Large animal models of SND allow characterization of SAP, which might be a target for novel treatment strategies for SAN diseases.

Methods

A goat model of SND was developed (n = 10) by epicardially ablating the SAN and validated by mapping of emergent SAP locations through an ablation catheter and surface electrocardiogram (ECG). Structural characterization of the goat SAN and SAP was assessed by histology and immunofluorescence techniques.

Results

When the SAN was ablated, SAPs featured a shortened atrioventricular conduction, consistent with the location in proximity of atrioventricular junction. SAP recovery time showed significant prolongation compared to the SAN recovery time, followed by a decrease over a follow-up of 4 weeks. Like the SAN tissue, the SAP expressed the main isoform of pacemaker hyperpolarization-activated cyclic nucleotide-gated channel 4 (HCN4) and Na⁺/Ca²⁺ exchanger 1 (NCX1) and no high conductance connexin 43 (Cx43). Structural characterization of the right atrium (RA) revealed that the SAN was located at the earliest activation [i.e., at the junction of the superior vena cava (SVC) with the RA] and was surrounded by the paranodal-like tissue, extending down to the inferior vena cava (IVC). Emerged SAPs were localized close to the IVC and within the thick band of the atrial muscle known as the crista terminalis (CT).

Conclusions

SAN ablation resulted in the generation of chronic SAP activity in 60% of treated animals. SAP displayed development over time and was located within the previously discovered PNA in humans, suggesting its role as dominant pacemaker in SND. Therefore, SAP in goat constitutes a promising stable target for electrophysiological modification to construct a fully functioning pacemaker.

Focal atrial tachycardia-the localization differences between men and women: A study of 487 consecutive patients

Objective:

The preferential sites for focal atrial tachycardia (FAT) are mainly in the right atrium in both sexes. However, a limited number of studies have indicated that sex differences in the localization of FAT. This study investigated possible sex differences in the distribution of FAT in a large cohort of patients referred for ablation.

Methods:

From 2004 to 2019, 487 patients (298 women) were referred to our institution for ablation of FAT. A standard electrophysiological study was conducted, and isoproterenol or atropine was given when needed. Conventional catheter mapping, electroanatomic contact mapping, and noncontact mapping were used to assess the origin of ectopic atrial tachycardia.

Results:

Overall, 451 foci were successfully ablated in 436 patients (90%). Although the foci located along the crista terminalis were more common in women than in men (42% vs. 29%; p=0.023), the opposite were found in the foci located along the tricuspid annulus (5% vs. 11%; p=0.032) and the right atrial appendage (RAA) (1% vs. 3%; p=0.032). Other locations were similarly distributed in men and women. In addition, the presence of persistent FAT was more frequent in men than in women (22% vs. 5%; p<0.001). Finally, the difference in the induction pattern of FAT was also remarkable between sexes.

Conclusion:

The distribution of FAT in women and men is different. In addition, persistent FAT seems more often in men than in women. The different distribution, persistency, and induction pattern of FAT should be considered in the successful management of this type of tachycardia. (Anatol J Cardiol 2020; 24: 405-9)

[Catheter ablation of supraventricular tachycardia]

Supraventricular tachycardias (SVT) are common, with atrioventricular nodal reentry tachycardias (AVNRT) being the most common paroxysmal supraventricular tachycardia. The pathophysiological understanding and the catheter ablation of SVTs have developed steadily in recent years. For example, dividing AVNRT into "typical" and "atypical" depending on the HA-, VA-interval and AH/HA ratio is recommended. Because of higher rates of recurrences after cryoablation, radiofrequency ablation has prevailed in AVNRT. The current ESC guidelines for SVTs recommend the ablation of accessory pathways in asymptomatic high-risk patients and it is now a Class I recommendation. There is no recommendation for the access in left-sided accessory pathways. However, a transseptal compared to transaortic approach seems more promising in acute success. The use of a three-dimensional (3D) mapping system leads to a reduction of the fluoroscopy times and procedure duration. Ablation of focal atrial tachycardia remains challenging despite the use of 3D electroanatomical mapping systems. However, new technologies such as high-density (HD) multipoint mapping systems can be helpful. HD mapping systems also allow a better understanding of left and right atrial macroreentry tachycardia after previous ablation or cardiac surgery and in primary nature. However, in all technological advances, a proficient understanding of the basic techniques in electrophysiology, such as entrainment mapping, is mandatory.

Embryology of the Cardiac Conduction System Relevant to Arrhythmias

Embryogenesis of the heart involves the complex cellular differentiation of slow-conducting primary myocardium into the rapidly conducting chamber myocardium of the adult. However, small areas of relatively undifferentiated cells remain to form components of the adult cardiac conduction system (CCS) and nodal tissues. Further investigation has revealed additional areas of nodal-like tissues outside of the established CCS. The embryologic origins of these areas are similar to those of the adult CCS. Under pathologic conditions, these areas can give rise to important clinical arrhythmias. Here, we review the embryologic basis for these proarrhythmic structures within the heart.