To better identify the Ectopics on ECG - Things needed to be known

This ECG is showing Atrial focus running around 240/min,  two or more ventricular foci competing , seems isorhythmic AV dissociation.

So it's sinus tachycardia with Bifascicular block pattern Right Bundle with left axis and p occurs at constant Rate but with ventricular ectopics occurring in bigeminal and trigeminal pattern with no fixed PR interval related hence favoring ventricular ectopic beat with Left ventricular outflow origin.

The Ventricular ectopics or ectopies creates lots of concerns , confusion and issue with labelling or terminologies and above all treatment / managment !!!!! 

Mostly these are over concerns however sometimes the concern can be very genuine esp in case of them occurring as closely coupled !!!

To better identify the Ectopies , the following needed to be known

Shortly coupled Ventricular Ectopy (VE) that seems to be lodging onto the preceding T wave (the famous term R on T) May actually be indicative of electrical instability of the heart and demands more observation & investigation ! 

On the basis of the morphology & axis of ectopy QRs on surface 12 lead ecg , EP can localise their likely inter cardiac origins and can also ascertain their clinical significance to a large extent 

VEs can arise from any part of the ventricles however most commonly they originate from the outflows of both ventricles, with a greater occurrence from the RV outflow region !!

A. the outflow origin VE ( typically idiopathic & largely benign) will have the following features on surface ecg 

1. inferior axis (positive QRS in the inferior leads) 

2. lBBB pattern for RV outflow 

3. atypical RBBB pattern if from LV outflow 

Behaviour of these outflow VEs can be variable ! 

Generally There are various presentations  

1. very often come as isolated beats,  

2. occasionally as couplets, 

3. sometimes can become non-sustained or even sustained monomorphic ventricular tachycardia ! 

B. His/Pukinje (more usually the terminal portion) origin ! The surface ecg features 

1. RBBB-like morphology 

2. may have either a superior or inferior axis, depending on whether they originate from the posterior or anterior fascicles, respectively! 

C. Fascicular origin ! The surface 12 lead ecg will show 

1. These VE may be of relatively narrow QRS less than 130 ms

2. May have sharp initial deflection,(as a result of rapidly-conducting fascicular tissue) 

3. R prime wave (R’) of greater amplitude than the R wave in leads V1 and V2!  (A feature that distinguishes an ectopic of fascicular origin from other LV VE) 

D. Papillary muscle origin 

VE of LV papillary muscles shows a more atypical RBBB shape ! The surface ecg  features will have 

1. slightly variable QRS morphologies (This variability is due to a single focus, most commonly closer to the tip of the muscle, but having a different exits towards the base) 

2. usually will have an R wave greater than the R’ wave in V1 

Catheter ablation is a potentially curative treatment even for these shortly/ closely coupled VE