--- In ekg_club@yahoogroups.com, "thatsuthant" <thatsuthant@...> wrote:
>
> Hi every one,
> How do you differentiate atrial ectopic beats from ventricular ectopic beats?. Any one can define me please?.
> Ventricular ectopic beats are clearly seen on ECG . But atrial ectopic beats, how you all find those?. Please give some of your thoughts.
>
> Thanks
>
>
>
> --- In ekg_club@yahoogroups.com, Klaus Skrudland <lapsklaus@> wrote:
> >
> > Hi all. Just want to present to you a case of what I believe is a quite
> > uncommon ectopic rhythm.
> >
> > The patient is a 55 y/o male with a well known paroxysmal atrial
> > fibrillation. He uses flecainide and metoprolol and was admitted for onset
> > of what he thought was atrial fibrillation.
> >
> > As you will see from the ecg, the ventricular rate is irregular. Right
> > precordial leads show ectopic, positive P waves. PP intervals are regular
> > with a rate of 230 bpm. When marching them out with a caliper (see the dots
> > I made), they seem to march right through the QRS complexes and don´t seem
> > to get conducted. However, there can´t be AV dissociation, as there is no
> > evidence of an escape pacemaker present (and the ventricular rate is
> > irregular).
> >
> > As a matter of fact, the P waves does seem to get conducted after all. My
> > colleague Terje (the other Norwegian here in the club) pointed out that the
> > PR interval in fact gets progressively longer. And at this point, I´m
> > struggling to understand the rest of the mechanism. Most likely, this atrial
> > tachycardia with some kind of Wenkebach conduction.
> >
> > Comments? Thoughts? Ideas? Anyone wanna make a ladderdiagram to explain the
> > mechanism?! ;-)
> >
> > klaus
> >
>

In the caes of a true atrial ectopic beat, the QRS will be preceded by a definite, upright P wave. P wave morphology may fulctuate (wandering pacemaker, etc.), but if the premature beat is truely atrial in origin then a P wave will be present. Another way to distinguish PACs from PVCs is to view them in leads I and III. Also remember that PACs have a QRS duration time of < 0.12 sec, whereas PVCs almost always have duration times > 0.12 sec.
If your sure that it's a PVC your looking at, you can determine L or R origin by viewing it in MCL1/v1. L vent PVCs will be positive in deflection while R vent PVCs will be aberrant. Hope this helps.