PVC - Premature Ventricular Capture and its types

 A premature ventricular contraction (PVC)/ventricular ectopy (VE) is a prematurely occurring wide QRS beat that has a very distinct shape ( shape depending upon site of origin) and is not preceded by a P wave!!!

So the most important to understand is ! 

Generally there are two major types of ventricular ectopies 

1. The most common especially in non acute settings are the idiopathic VE / the outflow origin VE . They generally are Positive in inferior leads 

2. ⁠the non outflow or the structural heart ectopies !! They generally are negative in inferior leads

So 

Of The various Terminologies !!!! Or the observed behaviour on the ECG ! 

Some of the usual terminologies and which are usually very very confusing to the Jnr Drs but even some Snr colleagues !!!

So The patterns or them occurring on the surface ecg may be of the following types ! 

1. So Two consecutive ectopics (be called couplet)

2. alternating ectopy with normal QRS complex (be called bigeminy)

         Of all the shapes/patterns behaviour , this particular is a very commonly sustained rhythm disturbance , occurring more especially at night, and consisting of an alternating normally conducted beat with a Ectopy followed by a pause and a then resumption of the sequence. So This is referred to as ventricular bigeminy!!!!

3. A Ectopy occurring after every third normal beat (trigeminy). 

4. While Quadrigeminy means that in which every fourth beat is an ectopy (extrasystole) or three sinus beats occurring between extrasystoles.

5. Salvo is a period of three to five ectopics that occur repeatedly without any sinus beat/rhythm in between.

6. A certain number of these occurring at a certain continuous rate will Lead to be considered as ventricular tachycardia!!!

Have a look at this ECG:

Its Narrow complex sinus beats alternating with VPCs (of RBBB morphology) , with Ventricular rate of 90-100/min

Sinus beats have normal axis

VPCs having inferior axis

STs following sinus beats show ST elevations <1 mm in lead 1, ~1mm in AvL with inverted T waves, marked upsloping ST depressions with upright T waves in leads V2-V6

Impression: Ventricular bigeminy

Likely causes in the order of:

Digitalis effect

Ischemia

Electrolyte disturbance

Metabolic derangements

Hope you enjoyed learning about PVCs.

Thanks