Intracardiac Echocardiography to Guide Catheter Ablation of Atrial Fibrillation

Cardiovascular imaging techniques for electrophysiologists

Rapid technological advancements in noninvasive and invasive imaging including echocardiography, computed tomography, magnetic resonance imaging and positron emission tomography have allowed for improved anatomical visualization and precise measurement of cardiac structure and function. These imaging modalities allow for evaluation of how cardiac substrate changes, such as myocardial wall thickness, fibrosis, scarring and chamber enlargement and/or dilation, have an important role in arrhythmia initiation and perpetuation. Here, we review the various imaging techniques and modalities used by clinical and basic electrophysiologists to study cardiac arrhythmia mechanisms, periprocedural planning, risk stratification and precise delivery of ablation therapy. We also review the use of artificial intelligence and machine learning to improve identification of areas for triggered activity and isthmuses in reentrant arrhythmias, which may be favorable ablation targets.

Randomized Controlled Trial Comparing Training of Transseptal Puncture With or Without Intracardiac Echocardiography

BACKGROUND

Intracardiac echocardiography (ICE) has been widely used in the catheter ablation of atrial fibrillation (AF). However, the value of ICE in the training of transseptal puncture (TSP) is unclear.

METHODS

ICE-Training Study was a single-center, parallel-group, unmasked, randomized controlled trial registered in ChineseClinicalTrials.gov. Participants were randomly assigned (1:1) to different groups (1) the ICE simulator training group (ICE-ST), in which TSP was trained and performed under the guidance of both ICE and x-ray; and (2) the conventional simulator training group (Con-ST), in which TSP was trained and performed only under the guidance of x-ray. The trainees need to undergo the training stage and the evaluation stage.

RESULTS

From October 2022 to December 2022, 18 consecutive fellows (age 32.4 ± 4.4 years, 12 males) without experience of TSP were included. The training period (16.9 ± 6.6 vs. 29.6 ± 8.7 times, p = 0.003) and the fluoroscopy time (120.3 ± 25.3 vs. 189.3 ± 40.2 s, p < 0.001) of the ICE-ST group was significantly shorter than that of the Con-ST group. No significant difference was found in the comprehensive performance of TSP in the ICE-ST group (composite score 96.7 ± 5.7) and the Con-ST group (composite score 95.9 ± 6.3, p = 0.62), but the selection of TSP sites in the ICE-ST group was commonly better than that in the Con-ST group.

CONCLUSIONS

ICE could improve the efficiency of TSP training and optimize the site of TSP to facilitate catheter manipulation in the ablation.

TRIAL REGISTRATION

ChineseClinicalTrials.gov identifier: ChiCTR2200058377.

Step-by-step recommendations utilizing four-dimensional intracardiac echocardiography in left atrial appendage procedures

INTRODUCTION

Four-dimensional (4D) intracardiac echocardiography (ICE) is a novel cardiac imaging modality that has been applied to various workflows, including catheter ablation, tricuspid valve repair, and left atrial appendage occlusion (LAAO). The use of this type of advanced ICE imaging may ultimately allow for the replacement of transesophageal echocardiography (TEE) for LAAO, providing comparable imaging quality while eliminating the need for general anesthesia.

METHODS

Based on our initial clinical experience with 4D ICE in LAAO, we have developed an optimized workflow for the use of the NUVISION™ 4D ICE Catheter in conjunction with the GE E95 and S70N Ultrasound Systems in LAAO. In this manuscript, we provide a step-by-step guide to using 4D ICE in conjunction with compatible imaging consoles. We have also evaluated the performance of 4D ICE with the NUVISION Ultrasound Catheter versus TEE in one LAAO case and present those results here.

RESULTS

In our comparison of 4D ICE using our optimized workflow with TEE in an LAAO case, ICE LAA measurements were similar to those from TEE. The best image resolution was seen via ICE in 2-dimensional and multislice modes (triplane and biplane). The FlexiSlice multiplanar reconstruction tool, which creates an en-face image derived from a 4D volume set, also provided valuable information but yielded slightly lower image quality, as expected for these volume-derived images. For this case, comparable images were obtained with TEE and ICE but with less need to reposition the ICE catheter.

CONCLUSION

The use of optimized 4D ICE catheter workflow recommendations allows for efficient LAAO procedures, with higher resolution imaging, comparable to TEE.

Chinese guidelines for the diagnosis and management of atrial fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, significantly impacting patients' quality of life and increasing the risk of death, stroke, heart failure, and dementia. Over the past two decades, there have been significant breakthroughs in AF risk prediction and screening, stroke prevention, rhythm control, catheter ablation, and integrated management. During this period, the scale, quality, and experience of AF management in China have greatly improved, providing a solid foundation for the development of the guidelines for the diagnosis and management of AF. To further promote standardized AF management, and apply new technologies and concepts to clinical practice timely and fully, the Chinese Society of Cardiology of Chinese Medical Association and the Heart Rhythm Committee of Chinese Society of Biomedical Engineering jointly developed the Chinese Guidelines for the Diagnosis and Management of Atrial Fibrillation. The guidelines comprehensively elaborated on various aspects of AF management and proposed the CHA2DS2‑VASc‑60 stroke risk score based on the characteristics of the Asian AF population. The guidelines also reevaluated the clinical application of AF screening, emphasized the significance of early rhythm control, and highlighted the central role of catheter ablation in rhythm control.

Chinese Guidelines for the Diagnosis and Management of Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, significantly impacting patients' quality of life and increasing the risk of death, stroke, heart failure, and dementia. Over the past two decades, there have been significant breakthroughs in AF risk prediction and screening, stroke prevention, rhythm control, catheter ablation, and integrated management. During this period, the scale, quality, and experience of AF management in China have greatly improved, providing a solid foundation for the development of guidelines for the diagnosis and management of AF. To further promote standardized AF management, and apply new technologies and concepts to clinical practice in a timely and comprehensive manner, the Chinese Society of Cardiology of the Chinese Medical Association and the Heart Rhythm Committee of the Chinese Society of Biomedical Engineering have jointly developed the Chinese Guidelines for the Diagnosis and Management of Atrial Fibrillation. The guidelines have comprehensively elaborated on various aspects of AF management and proposed the CHA2DS2-VASc-60 stroke risk score based on the characteristics of AF in the Asian population. The guidelines have also reevaluated the clinical application of AF screening, emphasized the significance of early rhythm control, and highlighted the central role of catheter ablation in rhythm control.

Catheter navigation by intracardiac echocardiography enables zero-fluoroscopy linear lesion formation and bidirectional cavotricuspid isthmus block in patients with typical atrial flutter

INTRODUCTION

One of the most helpful aspects of intracardiac echocardiography (ICE) implementation in electrophysiological studies (EPS) is the real-time visualisation of catheters and cardiac structures. In this prospective study, we investigated ICE-guided zero-fluoroscopy catheter navigation during radiofrequency (RF) ablation of the cavotricuspid isthmus (CTI) in patients with typical atrial flutter (AFL).

METHODS AND RESULTS

Thirty consecutive patients (mean age 72.9 ± 11.4 years, 23 male) with ongoing (n = 23) or recent CTI-dependent AFL underwent an EPS, solely utilizing ICE for catheter navigation. Zero-fluoroscopy EPS could be successfully accomplished in all patients. Mean EPS duration was 41.4 ± 19.9 min, and mean ablation procedure duration was 20.8 ± 17.1 min. RF ablation was applied for 6.0 ± 3.1 min (50W, irrigated RF ablation). Echocardiographic parameters, such as CTI length, prominence of the Eustachian ridge (ER), and depth of the CTI pouch on the ablation plane, were assessed to analyse their correlation with EPS- or ablation procedure duration. The CTI pouch was shallower in patients with an ablation procedure duration above the median (4.8 ± 1.1 mm vs. 6.4 ± 0.9 mm, p = 0.04), suggesting a more lateral ablation plane in these patients, where the CTI musculature is stronger. CTI length or ER prominence above the respective median did not correlate with longer EPS duration.

CONCLUSIONS

Zero-fluoroscopy CTI ablation guided solely by intracardiac echocardiography in patients with CTI-dependent AFL is feasible and safe. ICE visualisation may help to localise the optimal ablation plane, detect and correct poor tissue contact of the catheter tip, and recognise early potential complications during the ablation procedure.

Combination of Intracardiac Echocardiography and Contact Force Sensing for Left Ventricular Papillary Muscle Arrhythmias

OBJECTIVES

The catheter ablation of ventricular arrhythmias (VAs) arising from the left ventricular (LV) papillary muscles (PMs) is challenging. This study sought to address whether the combination of intracardiac echocardiography (ICE) and contact force sensing (CFS) can improve the acute and long-term ablation outcomes of left ventricular papillary muscle arrhythmias.

METHODS AND RESULTS

From May 2015 to August 2022, a total of thirty-three patients underwent catheter ablation for LV PM arrhythmias: VAs were located in anterolateral PMs in 11 and posteromedial PMs in 22. A combination of intracardiac echocardiography (ICE) and contact force sensing (CFS) was used in 21 of the 33 procedures. A mean of 6.93 ± 4.91 for lesions was used per patient, comparable between the CFS/ICE and no ICE/CFS (4.90 ± 2.23 vs. 10.17 ± 5.89; p = 0.011). The mean CF achieved in the ICE/CFS group was 7.52 ± 3.31 g. Less X-ray time was used in the combination group (CFS/ICE: 165.67 ± 47.80 S vs. no ICE/CFS: 365.00 ± 183.73 S; p < 0.001). An acute success rate of 100% was achieved for the ICE/CFS group (n = 22) and 66.67% for the no ICE/CFS group (n = 8). VA recurrence at the 11.21 ± 7.21-month follow-up was 14.2% for the ICE/CFS group and 50% for the no ICE/CFS group (p = 0.04). No severe complications occurred in all patients.

CONCLUSIONS

The combination of intracardiac echocardiography (ICE) and contact force sensing (CFS) could provide precise geometries of cardiac endocavitary structures and accurate contact information for the catheter during ablation, which improved acute and long-term ablation outcomes. The routine adoption of this strategy should be considered to improve the outcomes of LV PM VA ablation.

Intracardiac biopsy of cardiac tumors with echocardiographic guidance: Case report

Background

Primary cardiac tumors are very rare, and about 20-30% of them are malignant tumors. Since early signs of cardiac tumors are non-specific, diagnosis can be challenging. There is a lack of the recommended guidelines or standardized strategies for diagnosis and optimal treatment for this disease. As the definite diagnoses of most tumors are made by pathologic confirmation, biopsied tissue is essential in determining the treatment for patients with cardiac tumors. Recently, intracardiac echocardiography (ICE) has been introduced to assist biopsy procedures of cardiac tumors and it provides high-quality imaging.

Case Description

Due to its low prevalence and variable presentation, cardiac malignant tumors usually are easily missed. Hereby, we report three cases of patients who presented with non-specific signs of cardiac disorder and was initially suspended diagnosis as lung infection or cancer. Under the guidance of ICE, cardiac biopsies were successfully on cardiac masses, giving critical data for diagnosis and treatment planning. No procedural complications were obtained in our cases. These cases are intended to highlight the clinical value and importance of ICE-guided biopsy of intracardiac mass.

Conclusions

The diagnosis of primary cardiac tumors relies on the histopathological results. In our experience, using ICE for biopsy of an intracardiac mass is an attractive tool to increase diagnostic results and reduce the risk of cardiac complications associated with inadequate targeting of the biopsy catheters.

Feasibility of a novel algorithm for automated reconstruction of the left atrial anatomy based on intracardiac echocardiography

BACKGROUND

Intracardiac echocardiography (ICE) is frequently used to guide electrophysiology procedures. The novel automated algorithm Cartosoundfam is a model-based algorithm which reconstructs a 3D anatomy of the left atrium (LA) based on a set of 2D intracardiac echocardiography (ICE) frames, without the need to manually annotate ultrasound (US) contours.

OBJECTIVE

The aim of this study was to determine the feasibility of the Cartosoundfam module in routine clinical setting.

METHODS

We included 16 patients undergoing LA mapping/catheter ablation. Two-dimensional US frames were acquired from the right atrium (RA) and the right ventricular outflow tract. The Cartosoundfam map was validated in two steps: (1) identification of anatomical structures (pulmonary veins [PV] and LA body and appendage) by alignment of the ablation catheter to the automated map; and (2) analysis of the automated lesion tags (Visitag) location in relation to the PV antrum of the Cartosoundfam map in nine patients with paroxysmal atrial fibrillation (AF) undergoing first time pulmonary vein isolation (PVI).

RESULTS

Mean 2D US frames per patient were 29 ± 6 and acquisition time was 16 ± 4 min. All anatomical structures were correctly identified in all patients (step 1). In the step 2 validation, the median distance to the map was 2.0 (IQR: 2.4) mm and the majority of the Visitags were classified as satisfactory (69%) but all PV segments had some Visitags classified as unsatisfactory.

CONCLUSION

The automated ICE-based algorithm correctly identified the LA anatomical structures in all patients with a 69% anatomical accuracy of the Visitags alignments to the PV antrum segments.