Which Way to the Summit?

Abstract

A 57-year-old man presented with palpitations and dizziness for one day. He reported a history of similar short-lasting, self-limiting episodes in the past. Evaluation showed a hemodynamically stable, ongoing monomorphic ventricular tachycardia (VT) with positive concordance in the precordial leads and inferior axis. A structurally normal heart was seen on echocardiography. The VT was cardioverted to normal sinus rhythm with a biphasic 100-J direct-conversion shock under mild sedation, only to spontaneously start over again. In view of the patient's structurally normal heart, a previous history of similar complaints in the past, and no obvious trigger including ischemia for VT, he subsequently underwent an electrophysiology study (EPS).

Keywords: Ablation; great cardiac vein; idiopathic ventricular tachycardia; left ventricular summit.

Figure 1:

Upper panel: 12-lead ECG of tachycardia. Lower panel: rapid RA pacing during tachycardia. Presented are the surface ECG leads I, aVF, and V1 and intracardiac recordings. RAD: right atrial distal; RAP: right atrial proximal; HISD: His distal; HISP: His proximal.

Figure 1:

Upper panel: 12-lead ECG of tachycardia. Lower panel: rapid RA pacing during tachycardia. Presented are the surface ECG leads I, aVF, and V1 and intracardiac recordings. RAD: right atrial distal; RAP: right atrial proximal; HISD: His distal; HISP: His proximal.

Figure 2:

Upper panel: AV dissociation is apparent during VT. Signals at the left sinus of Valsalva and anterolateral mitral annulus (CS1,2) were noted relative to the surface QRS. Shown here are the surface ECG leads I, aVF, V1, and V6 and intracardiac recordings. CS: coronary sinus (higher numbers mean proximal electrodes and vice versa); RFD: ablation catheter distal; RFP: ablation catheter proximal; RFU: unipolar from the distal electrode of the ablation catheter. Lower panel: Corresponding sites on fluoroscopic images for left sinus of Valsalva (red arrow) and anterolateral mitral annulus (green arrow). Blue arrow points to the left ventricular outflow tract.

Figure 3:

Upper panel: site of earliest local signals, 30 ms earlier than the surface QRS with distinct presystolic potential (red arrow) recorded at this site. Shown here are the surface ECG leads I, aVF, V1, and V6 and intracardiac recordings. Middle panel: fluoroscopic views in LAO 40° and RAO 30° angles with the ablation catheter (white arrow). Lower panel: during RF energy delivery. Shown are the surface ECG leads I, aVF, V1, and V6 and intracardiac recordings.