Contemporary Management of Complex Ventricular Arrhythmias

Abstract

Percutaneous catheter ablation is an effective and safe therapy that can eliminate ventricular tachycardia, reducing the risks of both recurrent arrhythmia and shock therapies from a defibrillator. Successful ablation requires accurate identification of arrhythmic substrate and the effective delivery of energy to the targeted tissue. A thorough pre-procedural assessment is needed before considered 3D electroanatomical mapping can be performed. In contemporary practice, this must combine traditional electrophysiological techniques, such as activation and entrainment mapping, with more novel physiological mapping techniques for which there is an ever-increasing evidence base. Novel techniques to maximise energy delivery to the tissue must also be considered and balanced against their associated risks of complication. This review provides a comprehensive appraisal of contemporary practice and the evidence base that supports recent developments in mapping and ablation, while also considering potential future developments in the field.

Procedural Adaptations to Avoid Haemodynamic Instability During Catheter Ablation of Scar-related Ventricular Tachycardia

“… 22 As discussed by Wiles et al, omnipolar voltage mapping may circumvent this issue, although clinical experience in humans remains limited. 4 Finally, bipolar voltage mapping alone is relatively non-specific for VT isthmuses and, therefore, may lead to excessive ablation, particularly in patients with large areas of scar. Anter et al showed in swine models of infarct-related VT that VT isthmuses occupied only 18% of the low-voltage endocardium (<1.5 mV), and that low voltage was 72% sensitive, but only 56% specific for VT isthmuses.…”

“…At this point, operators may also consider ‘bail-out’ techniques targeting mid-myocardial substrate, such as bipolar ablation or low ionic irrigant ablation to generate larger ablation lesions. 4 , 42 …”

“…Entrainment mapping entails pacing the ventricle at a cycle length slightly shorter than that of the VT. Sites at which this pacing continuously resets the VT with concealed fusion, and at which the return cycle after the cessation of pacing is equal to the native tachycardia cycle length, are deduced to be critical areas of the VT circuit ( Figure 1A ). 4 …”

“…Epicardial mapping should be considered if not performed during the initial ablation -particularly for patients with NICM, a 12-lead ECG suggestive of an epicardial VT critical site, or cross-sectional imaging demonstrating epicardial LGE or late iodine enhancement. At this point, operators may also consider 'bail-out' techniques targeting midmyocardial substrate, such as bipolar ablation or low ionic irrigant ablation to generate larger ablation lesions 4,42. VT substrate mapping can include any of the above-mentioned techniques; however, for most patients, we prefer a functional substrate mapping approach using ILAM or targeting wave front discontinuity lines defined in at least one wave front.…”