ECG of the LV Summit

Answer: Sinus rhythm with borderline RBBB & frequent monomorphic PVC’s arising from the anterobasal left ventricle, (in this case it was specifically from the LV summit region – lets discuss how we can make an educated guess about this).

General VT localisation features present on this ECG:

• Early precordial transition (- essentially when is the 1st dominantly positive precordial lead?) ≤V3 generally denotes an LV origin. When precordial transition occurs between V2-V3 as in this example, this usually indicates a “septal” LV origin – more on this later.

• Dominantly positive QRS complexes in V3-V6 indicate a basal origin.

Diagram explaining why Basal VT’s produce positive precordial leads

• Dominantly positive QRS complexes in II/III/aVF indicate an anterior origin.

Why is lead II positive in PVC’s arising from the Anterior wall of the LV?

• Dominantly –ve lead 1 indicates a lateral LV origin (this is discordant with the V3 transition mentioned earlier which indicated a septal origin).

More specific ECG features for LV Summit

Explaining Lead 1 & Precordial transition discordance

Atienza F, Arenal Á, Pérez-David E, et al. Circ Arrhythm Electrophysiol. 2013;6(6):e80–e84.

My two cents:

• The LV summit is in the anterobasal epicardial aspect of the LV – so ECG features of PVC’s arising from this location should be in keeping with with this.

• LV summit can be specifically suspected when there is also a very abrupt V3 precordial transition.

• The presence of septal-lateral ECG discordance can often occur in LV summit VT’s due to simultaneous lateral and septal wavefronts of depolarisation (in this case, Lead 1 is negative indicating a lateral origin, but an early V3 transition usually indicates a Septal LV origin).

Thanks for tuning in :)

Cheers
Mitch & CPiP Team

References:

• Cheung, J, Anderson, R, Markowitz, S. et al. Catheter Ablation of Arrhythmias Originating From the Left Ventricular Outflow Tract. J Am Coll Cardiol EP. 2019 Jan, 5 (1) 1–12.
• Atienza F, Arenal Á, Pérez-David E, Elízaga J, Ortuño JE, Ledesma-Carbayo MJ, Sánchez-Quintana D, Fernández-Avilés F. New diagnostic and therapeutic approaches to treat ventricular tachycardias originating at the summit of the left ventricle: role of merged hemodynamic-MRI and alternative ablation sources. Circ Arrhythm Electrophysiol. 2013 Dec;6(6):e80-4. 
• Richard A. Walsh, M.D. (2012). In J. W. Hurst, R. Walsh, V. Fuster, J. Fang, & R. A. O’Rourke (Eds.), Hurst’s The Heart Manual of Cardiology (13th ed., Vol. 39, pp. 1–882). McGraw Hill Professional. (www.accessmedicine.com)