Mapping and ablation of ventricular tachycardia using dual-energy lattice-tip focal catheter: early feasibility and safety study

Abstract

Aims: Catheter ablation is an effective treatment method for recurrent ventricular tachycardias (VTs). However, at least in part, procedural and clinical outcomes are limited by challenges in generating an adequate lesion size in the ventricular myocardium. We investigated procedural and clinical outcomes of VT ablation using a novel 'large-footprint' catheter that allows the creation of larger lesions either by radiofrequency (RF) or by pulsed field (PF) energy.

Methods and results: In prospectively collected case series, we describe our initial experience with VT ablation using a lattice-tip, dual-energy catheter (Sphere-9, Medtronic), and a compatible proprietary electroanatomical mapping system (Affera, Medtronic). The study population consisted of 18 patients (aged 55 ± 15 years, one woman, structural heart disease: 94%, ischaemic heart disease: 56%, left ventricular ejection fraction: 34 ± 10%, electrical storm: 22%) with recurrent sustained VTs and ≥1 previously failed endocardial RF ablation with conventional irrigated-tip catheter in 66% of patients. On average, 12 ± 7 RF and 8 ± 9 PF applications were delivered per patient. In three-fourths of patients undergoing percutaneous epicardial ablation, spasms in coronary angiography were observed after PF applications. All resolved after intracoronary administration of nitrates. No acute phrenic nerve palsy was noted. One patient suffered from a stroke that resolved without sequelae. Post-ablation non-inducibility of VT was achieved in 89% of patients. Ventricular-arrhythmia-free survival at three months was 78%.

Conclusion: VT ablation using a dual-energy lattice-tip catheter and a novel electroanatomical mapping system is feasible. It allows rapid mapping and effective substrate modification with good outcomes during short-term follow-up.

Keywords: Catheter ablation; Pulsed field; Radiofrequency ablation; Ventricular tachycardia.

Graphical Abstract

Figure 1

Examples of substrate modification in patients with VTs after previous myocardial infarction. Panels A to C show LV voltage maps in the right anterior oblique view in a patient with an extensive anteroseptal scar. Panels D to F depict LV voltage maps in posterior view in a patient after inferolateral myocardial infarction. Note the elimination of local voltage within the ablated zone after either core scar isolation (panel B) or substrate homogenization (panel E).

Figure 2

Panel A depicts epicardial (left) and endocardial (right) voltage map in the left lateral view in a patient with non-ischaemic cardiomyopathy. Panel B shows an epicardial activation map during sinus rhythm with delayed activation on the basal lateral wall (violet colour) with marked PF ablation tags (green). Note that the late potentials on both epicardial and endocardial local electrograms were eliminated by PF epicardial ablation. At the same time, the endocardial voltage was not affected. Panel C depicts mid-diastolic potentials in epicardium during inducible VT. Panel D shows the termination of VT during epicardial PF ablation. During PF application, note the myocardial capture (visible on ECG and arterial pressure tracing).

Figure 3

Panel A depicts a 12-lead ECG during VT in a patient with grown-up congenital heart disease after repeated surgical correction procedures and implantation of a balloon-expandable pulmonary stent valve. Panel B shows a voltage map of the RV with prominent scarring in the lateral RV outflow tract. Panel C shows the activation map during VT. The arrhythmia was successfully abolished by both radiofrequency (red tags) and pulsed field (green tags) ablation between the pulmonary valve stent and scarring on the RV lateral wall.

Figure 4

Example of coronary spasm induced by epicardial ablation on the lateral LV wall in vicinity of the marginal branch. Panel A shows preablation coronary angiography, panel B depicts the spasm of the marginal branch, and panel C shows the resolution of the spasm after intracoronary nitrate administration. Interestingly, no ECG changes were seen.

Figure 5

Panel A shows a 12-lead ECG of slow VT in a patient with non-ischaemic cardiomyopathy. Panel B shows an activation map during VT originating from RV inferoseptal processus. Despite extensive ablation, including the epicardial approach, VT recurred. During the re-ablation session, VT was successfully abolished by a conventional 4 mm irrigated-tip catheter inserted under the inferior leaflet of the tricuspid valve. Due to the larger size of the lattice tip, the catheter likely did not fit into the narrow space under the tricuspid valve, which could be then successfully cannulated and ablated with a 4 mm-tip catheter. Panels C and D show intracardiac echocardiography images with the position of the lattice-tip and 4 mm-tip close to the tricuspid annulus from the corresponding ablation sessions.