Endocardial, epicardial, and right atrial approach for catheter ablation of premature ventricular contractions from the inferoseptal process of the left ventricle

FIGURE 1. Twelve lead surface ECG describing the morphology of the premature ventricular contractions arising from the inferoseptal process of the ISP‐LV. All five patients had left superior QRS axis in the frontal plane and right bundle branch block morphology (RBBB) with no RS transition in the precordial leads except patient #4 who demonstrated left bundle branch block morphology (LBBB) in precordial lead V1 and early RS transition in V2.

FIGURE 2. Panel (A) Twelve lead ECG and intracardiac electrograms during the clinical ectopy at the site of successful ablation in patient 4; Panel (B) electroanatomical map of the basal portion of the left ventricle in the posteroanterior view showing the earliest ventricular activation site (white isochrone) at the endocardium of the inferoseptal process of the left ventricle (ISP‐LV); Panel (C): left—intracardiac echocardiography image of the ISP‐LV (marked by the red line); right—the position of ablation catheter at the successful ablation site at the ISP‐LV. ABL, mapping/ablation catheter; ABLd, intracardiac electrogram from the distal bipole of the mapping/ablation catheter; ABLp, intracardiac electrogram from proximal bipole of the mapping/ablation catheter; ABLuni, unipolar intracardiac electrogram from the tip of the mapping/ablation catheter; Ao, Aorta; ISP‐LV, inferoseptal process of the left ventricle; LV, left ventricle; PPM, posterior papillary muscle; RVAd, intracardiac electrogram from the distal bipole of the catheter, positioned at the right ventricular apex; Stim, stimulation channel.

FIGURE 3. The upper panel shows an anatomical map of the basal portion of the left ventricle (LV), inferoseptal region of the right atrium (RA), and coronary sinus (CS) in case no. 5. The lower panel shows the earliest LV endocardial activation preceding the QRS onset by 26 ms positioned at the ISP‐LV (left). Subsequent mapping revealed earlier activation in the CS, especially at the MCV ostium where the earliest electrogram preceded the QRS onset by 28 ms (middle). Mapping the RA inferoseptal region demonstrated even earlier activation preceding the surface ECG by 31 ms (right). Ablation at this latter point eliminated the ectopic activity from both the ISP‐LV. AV ratio between 3:1 and 5:1 could be seen while mapping MCV and RA inferoseptum. AoV, aortic valve; CS, coronary sinus. The other abbreviations as in Figure 2.

FIGURE 4. Panel (A, B, and C) represent the left anterior oblique (LAO) and right anterior oblique (RAO) fluoroscopic view of the catheter position and pace‐map from the successful endocardial ablation site of PVCs arising from the inferoseptal process of the left ventricle (ISP‐LV) in patient 1. The ablation catheter lies on the basal and septal portion of the left ventricle, just beneath the aortic valve where a good pace‐map match at the successful ablation site was achieved. Panels (D and E) represent the LAO and RAO view of retrograde venography of the CS in patient 2 in whom the PVCs were successfully ablated from the coronary venous system as explained in the text. Panel F shows local ventricular activation timing endocardially (30 ms pre‐QRS) and epicardially (55 ms, pre‐QRS), recorded into the proximal part of the middle cardiac vein (MCV) in the same patient. The good PVC pace‐map match was recorded from the same location as the mapping/ablation catheter. ABL, mapping/ablation catheter; CS, coronary sinus catheter; ICE, intracardiac echocardiography catheter; RV, right ventricle catheter. Sweep speed for all recordings is 100 mm/s.

FIGURE 5. Schematic representation of the anatomical relations of the inferoseptal process of the left ventricle (ISP‐LV) to the adjacent structures. The yellow arrows show the three possible approaches (endocardial and epicardial from CS and RA) for the ablation of PVCs originating from the ISP‐LV. CS, coronary sinus ostium; LV, left ventricle; MCV, Middle cardiac vein; NCC, noncoronary cusp of the aortic valve; LCC, left coronary cusp of the aortic valve; RA, right atrium.