Catheter Ablation for Premature Ventricular Contractions in the Left Coronary Sinus Cusp in a 16-Year-Old Girl Using a Zero-Fluoroscopy Approach

Abbreviations

ASC, Aortic sinus cusp

EAM, Electroanatomical mapping

ECG, Electrocardiogram

EP, Electrophysiological study

ICE, Intracardiac echocardiography

LBBB, Left bundle branch block

LVOT, Left ventricle outflow tract

PVCs, Premature ventricular contractions

RF, Radiofrequency energy

RVOT, Right ventricle outflow tract

VAs, Ventricular arrhythmias

ZF, Zero fluoroscopy

INTRODUCTION

Catheter ablation is a relatively safe and alternative treatment for children with frequent premature ventricular contractions (PVCs).¹ Many patients with PVCs do not show symptoms, but the PVC burdens exceed 30%, causing cardiomyopathy and heart failure in children. The use of catheter ablation for PVCs in children is still subject to debate.² In the past, fluoroscopy was required to access the heart anatomy during this procedure. However, radiation exposure from fluoroscopy can increase the risk of cancer and genetic mutations in children. Recent advances in three-dimensional mapping systems have allowed the use of limited or zero fluoroscopy (ZF) approaches for the ablation of arrhythmias.³ However, ablation of the aortic sinus cusp (ASC) for ventricular arrhythmias (VAs) poses a challenge due to its proximity to the coronary artery, particularly in pediatric patients. We report a 16-year-old girl who used a ZF approach to ablate PVCs in the left coronary cusp.

CASE REPORT

A 16-year-old girl had been suffering from chest tightness, dizziness, and headache for 12 months. Sinus rhythm with PVCs, showing RS in lead V1 and R in leads II, III, and aVF, with a left bundle branch block pattern (LBBB) and right inferior axis QRS morphology on 12-lead electrocardiogram (ECG) (Figure 1). Transthoracic echocardiography demonstrated normal cardiac function without structural heart disease. The Holter monitor ECG results recorded monomorphic LBBB-type PVCs without nonsustained ventricular tachycardia, with a total of 21,164 PVCs per day and a PVC burden of 18.66%. Initially, no medication was prescribed. However, as her symptoms persisted, she received propranolol at a dose of 5 mg twice daily. She also sought medical attention from multiple hospitals where she was prescribed oral atenolol at a dose of 50 mg once daily and propafenone at a dose of 150 mg three times daily. Unfortunately, these medications did not effectively alleviate her symptoms or reduce the frequency of PVCs. Consequently, she underwent an electrophysiological study (EP).

Figure 1.

12-lead electrocardiogram showed sinus rhythm with PVCs, showing RS in lead V1 and R in leads II, III, and aVF, with a LBBB and right inferior axis QRS morphology. It was suspected that they originated from the LVOT. LBBB, right bundle branch block pattern; LVOT, left ventricular outflow tract; PVCs, premature ventricular contractions.

General anesthesia was administered and antiarrhythmic drugs were withdrawn for 3 days prior to EP. On the basis of the morphology of the patient’s PVCs, it was suspected that they originated from the outflow tract. The Abbott EnSite NavX mapping system was used to create a detailed map of the right ventricle outflow tract (RVOT) and the left ventricle outflow tract (LVOT). A steerable decapolar mapping catheter (Livewire^TM, 2-2-2 mm spacing electrodes, Abbott, St. Jude Medical, St. Paul, MN, USA) was used to navigate the venous route to the right atrium and was deployed in the coronary sinus through femoral venous access. A 5-Fr multipolar catheter (Inquiry^TM, Abbott, St. Jude Medical, St. Paul, MN, USA) was placed in the right ventricle, and His bundle and right ventricle apex signals were recorded simultaneously. A decapolar mapping catheter (Livewire^TM, 2-2-2 mm spacing electrodes, St. Jude Medical, St. Paul, MN, USA) was located in the upper right atrium and was used for mapping. After placing the catheters, a 3D anatomical reconstruction and electroanatomical mapping (EAM) of RVOT and LVOT were created to guide the mapping and ablation procedures. Medical and nursing staff did not wear lead aprons during the procedure, which was in line with our routine catheterization laboratory policy. The mapping catheter was inadvertently advanced into the left main coronary artery during the procedure (Figure 2). A local activation time map of RVOT, LVOT, and aorta was generated. RVOT activation mapping showed the earliest location of RVOT ventricular activation on the anterior free wall, which was 21 ms earlier than the QRS complex on the surface ECG. Activation mapping of the LVOT and aorta showed that the earliest local ventricular activation was identified in the left coronary sinus cusp below the ostium of the left main coronary artery, which was detected 42 ms earlier than the QRS complex in the surface ECG (Figure 2). The distance from the catheter tip to the LMCA ostia is 9.2 mm. Furthermore, a sharp unipolar QS was observed in the ablation catheter (Figure 2). The pace map maneuver revealed that the QRS morphology during the pace resembled that of spontaneous PVCs and the pace map score was 99. A 4-mm flexible tip open-irrigated catheter (7Fr, FlexAbility^TM, Abbott, St. Jude Medical, St. Paul, MN, USA) was used to ablate the ASC through the right femoral artery. Radiofrequency energy (RF) was administered in power control mode, with a maximum temperature of 43 °C, a maximum power of 30 W and an irrigation rate of 13 ml/min for 60 seconds, which successfully eliminated PVC. However, the PVCs recurred immediately after discontinuation of the RF energy application. Subsequently, a second 35 W RF pulse was delivered, followed by further suppression of the PVCs. Several 35 W RF pulses were delivered around the target lesion as a booster. Following the procedure, the patient maintained a sinus rhythm without PVCs. The fluoroscopy time was 0 second during the procedure, and coronary angiography was not performed before or after the procedure. PVCs were limited to 24 beats on the 24-hour Holter ECG at 2 months of follow-up.

Figure 2.

The mapping catheter was inadvertently advanced into the LMCA during the procedure. Activation mapping of the LVOT and aorta showed that the earliest local ventricular activation was identified in the LCC below the ostium of the left main coronary artery (white area), which was detected 42 ms earlier than the QRS complex on the surface ECG. Furthermore, a sharp unipolar QS was observed in the ablation catheter (yellow arrow). ECG, electrocardiogram; LCC, left coronary sinus cusp; LMCA, left main coronary artery; LVOT, left ventricular outflow tract; RCC, right coronary sinus cusp.

DISCUSSION

Considering the risk of radiation exposure, ZF ablation has become the mainstay ablation policy in pediatric arrhythmias.³ However, ASC ablation is uncommonly performed in children, although it is used in 10-15% of VAs ablation in the adult population.⁴ This is probably due to two causes. First, arrhythmias arising from ASC are rare in children. Second, the risks associated with ASC ablation, including possible complications of aortic valve or coronary artery injury, are potentially profound in children. Therefore, ablation of the ASC of VAs is still a challenge in the pediatric group, not in the ZF procedure.

Before the EP study, prediction of the location of PVCs using 12-lead ECG aids in preparing special tools and understanding the local anatomy of the heart. This approach minimizes the time required for mapping procedures. Based on the diagnostic algorithm,⁵ the LBBB pattern in lead V1, inferior axis in lead II, III, and aVF. and RS or rS in lead V1 suggest the likelihood that PVC originates from the left coronary cusp. Therefore, the focus was on the structure of the LCC before the EP study.

Catheter ablation in the ASC is a challenging procedure due to the intricate anatomic relationships of the aortic valve, coronary arteries, and veins. Traditionally, coronary angiography or intracardiac echocardiography (ICE) is required before catheter ablation in the aortic cusps to ensure a safe distance from the coronary ostia.¹ Alternatively, EAM can be used to guide the position of the ablation catheter tip in the ASC and evaluate its location in relation to the left main and right coronary ostia before administering RF.⁶ In this case, to ensure the safety of the procedure, a mapping catheter was used to locate the left coronary ostia and maintain a safe distance between the ablation site and the coronary ostia.

Although ASC ablation in pediatric patients is not common, some studies have demonstrated its effectiveness.⁷ Ergul Y, et al. reported successful ablation in 22 pediatric patients with VAs originating from the ASC, with the LCC being the most frequent ablation site.¹ However, there have been few reports of ZF ablation of ASC PVCs in children.¹ In an adult study, PJ Sánchez-Millán et al. used a ZF approach guided by 3D integration of ICE in the EAM system for ASC PVC ablation in ten adult patients.⁶ Styczkiewicz K, et al. reported a multicenter analysis of the ZF approach without ICE for idiopathic VAs originating from the ASC.⁸ The short- and long-term success rates were 86% and 85%, respectively. In general, current evidence suggests that ZF ablation for ASC PVC is safe and effective in adults. Our study further confirms the feasibility and safety of ZF EAM guided ablation in the pediatric population.

LEARNING POINT

We report a case of catheter ablation for PVC in the left coronary sinus cusp of 16 years of age. Ablation of the ASC for VAs poses a challenge due to its proximity to the coronary artery, especially in children. To avoid radiation exposure in children, ZF ablation for ASC PVC was successful. Our study proposes that ZF ablation with EAM for PVCs originating from ASC may be effective and safe in children without the need for ICE.

DECLARATION OF CONFLICT OF INTEREST

The authors declare no conflicts of interest.

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.

FUNDING

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.