Real-time cardiovascular magnetic resonance-guided radiofrequency ablation: A comprehensive review

Abstract

Cardiac magnetic resonance (CMR) imaging could enable major advantages when guiding in real-time cardiac electrophysiology procedures offering high-resolution anatomy, arrhythmia substrate, and ablation lesion visualization in the absence of ionizing radiation. Over the last decade, technologies and platforms for performing electrophysiology procedures in a CMR environment have been developed. However, performing procedures outside the conventional fluoroscopic laboratory posed technical, practical and safety concerns. The development of magnetic resonance imaging compatible ablation systems, the recording of high-quality electrograms despite significant electromagnetic interference and reliable methods for catheter visualization and lesion assessment are the main limiting factors. The first human reports, in order to establish a procedural workflow, have rationally focused on the relatively simple typical atrial flutter ablation and have shown that CMR-guided cavotricuspid isthmus ablation represents a valid alternative to conventional ablation. Potential expansion to other more complex arrhythmias, especially ventricular tachycardia and atrial fibrillation, would be of essential impact, taking into consideration the widespread use of substrate-based strategies. Importantly, all limitations need to be solved before application of CMR-guided ablation in a broad clinical setting.

Keywords: Catheter ablation; Cavotricuspid isthmus; Image-guided ablation; Interventional cardiac magnetic resonance; Substrate ablation; Tracking.

Figure 1

Full transformation of the pre-existing magnetic resonance imaging environment into an interventional cardiac magnetic resonance imaging suite. A: Pre-existing diagnostic magnetic resonance imaging (MRI) scanner room; B: Pre-existing diagnostic MRI control room; C: Transformed interventional cardiac magnetic resonance (iCMR) suite; D: Transformed iCMR control room. E: The non-MR compatible RF generator including cooling-pump positioned in the iCMR control room. EP, electrophysiological; iCMR, interventional cardiac MRI. Citation: Bijvoet GP, Holtackers RJ, Smink J, Lloyd T, van den Hombergh CLM, Debie LJBM, Wildberger JE, Vernooy K, Mihl C, Chaldoupi SM. Transforming a pre-existing MRI environment into an interventional cardiac MRI suite. J Cardiovasc Electrophysiol 2021; 32: 2090-2096 [PMID: 34164862 DOI: 10.1111/jce.15128]. Epub 2021 Jul 4. Copyright © 2021 The Authors. Journal of Cardiovascular Electrophysiology published by Wiley Periodicals LLC. (Reproduced with permission)[13].

Figure 2

9 Fr. bipole irrigated-tip ablation catheter with two magnetic resonance receive coils in the distal end for active magnetic resonance tracking. (Reproduced with permission from https://imricor.com).

Figure 3

Distortion of the electrograms within the magnetic field. A: Baseline noise of intra-cardiac electrograms recorded with the coronary sinus catheter (blue arrows indicate the maximally distorted signal); B: Gradient-induced artifacts that cause high frequency peaks during magnetic resonance scanning (orange arrows). ABLc: Ablation catheter; CATH2c: Coronary sinus catheter.

Figure 4

Imaging with T2 mapping detects inflamed edematous tissue. A and B: T2-weighted magnetic resonance images of the cavotricuspid isthmus in the RAO view before (A) and after (B) ablation showing edema in the ablation lesions, indicated by the yellow arrows. Citation: Bijvoet GP, Holtackers RJ, Nies HMJM, Mihl C, Chaldoupi SM. The role of interventional cardiac magnetic resonance (iCMR) in a typical atrial flutter ablation: The shortest path may not always be the fastest. Int J Cardiol Heart Vasc 2022; 41: 101078. [PMID: 35800043 DOI: 10.1016/j.ijcha.2022.101078]. Copyright © 2022 The Authors. Published by Elsevier B.V. (Reproduced under the terms of the Creative Commons CC-BY license)[44].

Figure 5

Acute lesion after radiofrequency ablation of the right cavotricuspid isthmus. A: Balanced steady-state free precision sequence image of the cavotricuspid isthmus (CTI) immediately after ablation. White asterisk indicates pericardial effusion. White arrow indicates a prominent eustachian valve; B and C: T2-weighted images preablation (B) and postablation (C) showing signal intensity enhancement of the isthmus line (white arrows); D: Noncontrast enhanced T1-weighted image of the CTI depicts acute necrotic lesions as signal intensity loss (black arrow); E: Postcontrast early enhancement image shows hypoenhanced myocardium localized at the CTI, known as a microvascular obstruction as an acute ablation lesion sign; F: Phase-sensitive inversion recovery image depicts acute ablation lesion in terms of black, hypoenhanced myocardium; G: Postcontrast late gadolinium enhancement images led to partially enhanced radiofrequency ablation lesions (white edge) with black necrotic core (black arrow). Citation: Ulbrich S, Huo Y, Tomala J, Wagner M, Richter U, Pu L, Mayer J, Zedda A, Krafft AJ, Lindborg K, Piorkowski C, Gaspar T. Magnetic resonance imaging-guided conventional catheter ablation of isthmus-dependent atrial flutter using active catheter imaging. Heart Rhythm O2. 2022; 3: 553-559 [PMID: 36340492 DOI: 10.1016/j.hroo.2022.06.011]. Copyright © 2022 Heart Rhythm Society. Published by Elsevier Inc. (Reproduced under the terms of the Creative Commons CC-BY license)[40].

Figure 6

Isthmus pouches that are frequently present, a prominent Eustachian ridge and large pectinate muscles may impede catheter stability and navigation to target sites leading to poor tissue contact and low radio frequency energy delivery. A and B: Septal pouch (white arrow) of the cavotricuspid isthmus in a balanced steady-state free precision sequence image [as visualized in the transversal plane (B)]; C: Kinking of the vena cava inferior junction in the right atrium (white arrow) and a eustachian valve (black arrow) was found. Anterior to the right ventricular apex, a pre-existing pericardial effusion was located (asterisk). Citation: Ulbrich S, Huo Y, Tomala J, Wagner M, Richter U, Pu L, Mayer J, Zedda A, Krafft AJ, Lindborg K, Piorkowski C, Gaspar T. Magnetic resonance imaging-guided conventional catheter ablation of isthmus-dependent atrial flutter using active catheter imaging. Heart Rhythm O2 2022; 3: 553-559 [PMID: 36340492 DOI: 10.1016/j.hroo.2022.06.011]. Copyright © 2022 Heart Rhythm Society. Published by Elsevier Inc. (Reproduced under the terms of the Creative Commons CC-BY license)[40].

Figure 7

Electroanatomic mapping systems compatible for use inside a magnetic resonance scanner have been developed. A: 3D electroanatomical activation mapping; B: Integration with real-time cardiac magnetic resonance imaging planes. (Reproduced with permission from https://imricor.com).