Differentiating Supraventricular and Ventricular Premature Contractions

While the differentiation of SVPCs and VPCs may often be straightforward, it can also be a challenge in that SVPCs may conduct with aberrancy (abnormally) resulting in bizarre and wide QRS morphology. Since clinical significance, therapy, and prognosis for one may be very different than for the other, it is important to attempt to differentiate these abnormalities.

A refers to the time between two normal sinus beats close to the premature beat. B refers to the time between the sinus beat just before the premature beat to the sinus beat just after the premature beat.

If A > B (this is called a non-compensatory pause), indicates the premature beat is a supraventricular beat.

If A < B (this is called a compensatory pause), indicates the premature beat is a ventricular beat.