Papillary Muscle Ventricular Tachycardia or Ectopy: Diagnostics, Catheter Ablation and the Role of Intracardiac Echocardiography

Transoesophageal echocardiography beyond the Echo-Laboratory. An expert consensus paper of the working group of echocardiography of the Hellenic Society of Cardiology

Transoesophageal echocardiography (TOE) is a well-established and valid imaging modality, providing more accurate and of higher quality information than transthoracic echocardiography (TTE) for several specific diagnoses and recently a useful guide of an increasing number of catheter-based and surgical interventions. The present paper represents an effort by the Echocardiography Working Group (WG) of the Hellenic Society of Cardiology to state the essential steps of the TOE exam performed beyond the echo lab: a) in the operating rooms intraoperatively during either transcatheter interventions, or cardiothoracic surgery and b) in the intensive care unit for critically ill patients' monitoring. This paper includes information and tips and tricks about the pre-procedural evaluation, the procedural echocardiographic guidance and post - procedural evaluation of the result and potential complications.

Ventricular tachycardia ablation in children

INTRODUCTION

The ablation of ventricular tachycardia, including premature ventricular contractions, is an approved, albeit infrequent procedure in pediatric patients. Data are scarce regarding the outcomes of this procedure. The purpose of this study was to share a high-volume center experience and patient outcomes for catheter ablation of ventricular ectopy and ventricular tachycardia in pediatric population.

METHODS

Data were retrieved from the institutional data bank. Outcomes over time were evaluated, and procedural details were compared.

RESULTS

A total of 116 procedures were performed on 102 pediatric patients between July 2009 and May 2021 at the Rajaie Cardiovascular Medical and Research Center in Tehran, Iran. Ablation was not performed in 4 procedures (3.4%) due to high-risk substrates. Of the remaining 112 ablations performed, 99 (88.4%) were successful. However, one patient died due to a coronary complication. There were no significant differences observed in early ablation results based on patients' age, sex, cardiac anatomy, or ablation substrates (P > 0.05). Follow-up records were available for 80 procedures, and 13 (16.3%) of those experienced recurrence. During long-term follow-up, none of the variables mentioned above were statistically different between patients with or without arrhythmia recurrence.

CONCLUSION

The overall success rate of pediatric ventricular arrhythmia ablation is favorable. We found no significant predictor for the procedural success rate concerning acute and late outcomes. Larger multicenter studies are needed to elucidate the predictors and outcomes of the procedure.

An unusual origin of a papillary muscle of the right ventricle

Knowledge of anatomical variations of the heart are important to cardiac surgeons, cardiologists, and radiologist. During routine dissection of a 77-year-old male cadaver, we observed an unusual origin of a papillary muscle of the right ventricle arising from the atrioventricular aspect of the moderator band. This papillary muscle was 6.7mm long and 2.6mm wide. It gave rise to two chordae tendineae: one to the inferior (posterior) papillary muscle of the right ventricle and one directly to the inferior (posterior) leaflet of the tricuspid valve. Variants of the internal anatomy of the heart as exemplified in the present case report should be born in mind during image interpretation and invasive procedures of the right ventricle of the heart.

Needle-Tipped Catheter Ablation of Papillary Muscle Results in Deeper and Larger Ablation Lesions

Ventricular tachycardia associated with papillary muscle (PM) is often refractory to standard radiofrequency ablation (RFA). The needle-tipped ablation catheter (NT-AC) has been used to treat deep intramyocardial substrates, but its use for PM has not been characterized. Using an ex vivo experimental platform, both 3 mm and 6 mm NT-AC created larger ablation lesion volumes and depths than open-irrigated ablation catheter did (OI-AC; e.g., 57.12 ± 9.70mm³ and 2.42 ± 0.22 mm, respectively; p < 0.01 for all comparisons). Longer NT-AC extension (6 mm) resulted in greater ablation lesion volumes and maximum depths (e.g., 333.14 ± 29.13mm³ and 6.46 ± 0.29 mm, respectively, compared to the shorter 3 mm NT-AC extension, 143.33 ± 12.77mm³, and 4.46 ± 0.14 mm; both p < 0.001). There were no steam pops. In conclusion, for PM ablation, the NT-AC was able to achieve ablation lesions that were larger and deeper than with conventional OI-AC. Ablation of PM may be another application for needle-tip ablation. Further studies are warranted to establish long-term safety and efficacy in human studies.

Behind Enemy Lines: Vital Echocardiographic Data Prior to Ventricular Arrhythmia Ablation

Ventricular arrhythmias (VA) are a major cause of sudden cardiac death (SCD). Echocardiography is the first widely available imaging tool which guides VA management strategies. Along with other invasive and noninvasive imaging techniques, it provides essential information for identification of VA substrate such as differentiation between ischemic and non-ischemic etiology and identification of structural heart disease. Both classic as well as novel echocardiographic techniques such as left ventricular strain measurement and mechanical dispersion assessment provide prognostic information and assist in risk stratification. Furthermore, intracardiac echocardiography may have an adjunctive role for the VA ablation by providing real-time visualization of cardiac structures, continuous monitoring of catheter location and early recognition of procedural complications. This review gathers all relevant information that echocardiography may offer prior to VA ablation procedures.

Short-coupled ventricular ectopics leading to cardiac arrest in a young woman

BACKGROUND

This case report highlights the importance of recognizing that ventricular ectopy may be a cause for syncope and sudden cardiac death, through triggered disorganized arrhythmia. In the context of syncope, ventricular ectopy should be carefully assessed for coupling interval and morphology.

CASE PRESENTATION

A 39-year-old woman, who had presented with recurrent syncope, had a cardiac arrest shortly after admission that required emergency defibrillation. Review of her cardiac monitoring revealed an episode of polymorphic ventricular tachycardia which had degenerated into ventricular fibrillation. The dysrhythmia had been initiated by a short-coupled (R-on-T) ventricular ectopic (VE) beat. Anti-arrhythmic therapy was initiated in the form of hydroquinidine, but the patient continued to have frequent VEs of right bundle branch block (RBBB) morphology with a relatively narrow QRS complex and a variation in frontal axis. A cardiac MRI revealed late gadolinium enhancement of the posterior papillary muscle (indicative of focal scarring). The patient underwent electrophysiological mapping and catheter ablation of her ectopy. The patient made a good recovery and was discharged from hospital with a secondary prevention implantable cardioverter-defibrillator (ICD) in situ.

CONCLUSIONS

Short-couped VEs that are superimposed onto the preceding T wave (R-on-T) are indicative of electrical instability of the heart and should prompt urgent investigation. By studying the morphologies and axes of the QRS complexes produced by VEs, we can identify their likely origins and ascertain their clinical significance.

Perpendicular Catheter Orientation During Papillary Muscle Ablation Results in Larger, Deeper Lesions

INTRODUCTION

Ablation of papillary muscles (PM) for refractory ventricular arrhythmias can often be challenging. The catheter approach and orientation during ablation may affect optimal radiofrequency (RF) delivery. Yet, no previous study investigated the association between catheter orientation and PM lesion size. We evaluated ablation lesion characteristics with various catheter orientations relative to the PM tissue during open irrigated ablation, using a standardized, experimental setting.

METHODS

Viable bovine PM was positioned on a load cell in a circulating saline bath. RF ablation was performed over PM tissue at 50W, with the open irrigated catheter positioned either perpendicular or parallel to the PM surface. Applied force was 10 grams. Ablation lesions were sectioned and underwent quantitative morphometric analysis.

RESULTS

A catheter position oriented directly perpendicular to the PM tissue resulted in the largest ablation lesion volumes and depths compared to ablation with the catheter parallel to PM tissue (75.26±8.40 mm³ vs. 34.04±2.91 mm³ , p<0.001) and (3.33±0.18 mm vs. 2.24±0.10 mm, p<0.001), respectively. There were no significant differences in initial impedance, peak voltage, peak current, or overall decrease in impedance among groups. Parallel catheter orientation resulted in higher peak temperature (41.33±0.28°C vs. 40.28±0.24°C, p=0.003), yet, there were no steam pops in either group.

CONCLUSION

For PM ablation, catheter orientation perpendicular to the PM tissue achieves more effective and larger ablation lesions, with greater lesion depth. This may have implications for the chosen ventricular access approach, the type of catheter used, consideration for remote navigation, and steerable sheaths. This article is protected by copyright. All rights reserved.

Brugada syndrome unmasked by left ventricle posteromedial papillary muscle ventricular tachycardia: Coincidence or consequence

A 46-year-old man presented with left ventricle posteromedial papillary muscle ventricular tachycardia, presyncope, and a type-1 Brugada pattern on the post-electrical cardioversion electrocardiogram. There was a probability of a Brugada syndrome with the expression of its disease in the left ventricle; or a left monomorphic ventricular tachycardia as a part of Brugada phenocopy; or a Brugada syndrome with left monomorphic ventricular tachycardia as an epiphenomenon. Cardiac magnetic resonance, electrophysiological study, and ajmaline test were the key diagnostic tools employed.

Remote magnetic-guided ablation for three origins of idiopathic ventricular arrhythmias with right bundle branch block and superior axis

Background

Idiopathic ventricular arrhythmias (IVAs) with right bundle branch block (RBBB) and superior axis commonly originate from posterior mitral annulus (PMA), the left ventricular (LV) posterior fascicle (LPF), and the LV posterior papillary muscles (PPM).

Hypothesis

Remote magnetic navigation (RMN)‐guided ablation might be safe and effective for these three origins of IVAs.

Methods

Thirty consecutive IVA patients with RBBB and superior axis (11 MPA‐IVAs, 11 LPF‐IVAs, and 8 PPM‐IVAs) were included in this study. Electrical mapping and ablation with RMN were performed in the LV through a trans‐septal approach. Navigation index, defined as the ratio of total radiofrequency (RF) time and the time from first burn to last burn, was used to determine the efficiency of RMN‐guided ablation.

Results

The overall acute success rate was achieved in 93% (PMA, 100%; LPF, 91%; PPM, 88%; p > 0.05). No complication occurred in this study. The procedure time of PPM‐IVAs group was 34 and 14 min longer when compared with MPA‐IVAs and LPF‐IVAs group, respectively, without an increase of X‐ray time. The mean navigation index was 0.45 ± 0.20. The PPM‐IVAs group had an underperforming navigation index value (0.29 ± 0.11) (p < 0.01), as longer RF time was required in the PPM‐IVAs group.

Conclusions

RMN‐guided ablation can achieve a high acute success rate for IVAs with RBBB and superior axis. The lower navigation index for PPM‐IVAs indicated that increasing the RF time and improving the catheter contact should be considered when using RMN.

QRS morphology in lead V1 for the rapid localization of idiopathic ventricular arrhythmias originating from the left ventricular papillary muscles: A novel electrocardiographic criterion

BACKGROUND

Twelve-lead electrocardiogram (ECG) criteria have been developed to identify idiopathic ventricular arrhythmias (VAs) from the left ventricular (LV) papillary muscles (PAPs), but accurate localization remains a challenge.

OBJECTIVE

The purpose of this study was to develop ECG criteria for accurate localization of LV PAP VAs using lead V₁ exclusively.

METHODS

Consecutive patients undergoing mapping and ablation of VAs from the LV PAPs guided by intracardiac echocardiography from 2007 to 2018 were reviewed (study group). The QRS morphology in lead V₁ was compared to patients with VAs with a "right bundle branch block" morphology from other LV locations (reference group). Patients with structural heart disease were excluded.

RESULTS

One hundred eleven patients with LV PAP VAs (mean age 54 ± 16 years; 65% men) were identified, including 64 (55%) from the posteromedial PAP and 47 (42%) from the anterolateral PAP. The reference group included patients with VAs from the following LV locations: fascicles (n = 21), outflow tract (n = 36), ostium (n = 37), inferobasal segment (n = 12), and apex (5). PAP VAs showed 3 distinct QRS morphologies in lead V₁ 93% of the time: Rr (53%), R with a slurred downslope (29%), and RR (11%). Sensitivity, specificity, positive predictive value, and negative predictive value for the 3 morphologies combined are 93%, 98%, 98%, and 93%, respectively. The intrinsicoid deflection of PAP VAs in lead V₁ was shorter than that of the reference group (63 ± 13 ms vs 79 ± 24 ms; P < .001). An intrinsicoid deflection time of <74 ms best differentiated the 2 groups (sensitivity 79%; specificity 87%).

CONCLUSION

VAs originating from the LV PAPs manifest unique QRS morphologies in lead V₁, which can aid in rapid and accurate localization.

Electrophysiological Substrates in Papillary Muscle Arrhythmias – Implications for Catheter Ablation

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