This rhythm reflects Mobitz Type I AV block or Wenkebach, which is not usually secondary to structural abnormalities when the QRS complex is narrow, but is vagally mediated instead. Increased vagal tone occurs in the young or the athletic with frequencies ranging from 2 to 10%. No treatment is necessary unless the patient is symptomatic.
The PR interval progressively lengthens with each beat until the atrial impulse is not conducted and the QRS complex is dropped (Wenckebach phenomenon); AV nodal conduction resumes with the next beat, and the sequence is repeated.
We therefore interpret this tracing as showing “AV dissociation” – since at least some P waves are unrelated to the QRS complexes that follow them. The term AV dissociation should never be used as a “diagnosis” per se. Instead – it is the result of the underlying rhythm on the tracing. In this case – the underlying rhythm is sinus bradycardia at a rate of 50/minute (the P-P interval is precisely 6 large boxes in duration for each of the P waves on this tracing). AV dissociation occurs by…
Ventricular Fibrillation V-fib is a cardiac arrest rhythm. It will NEVER have a pulse associated with it as the ventricles are quivering or "fibrillating," not contracting. Survival from this lethal rhythm requires immediate CPR, defibrillation, and ACLS procedures. V-fib is characterized by chaotic indistinguishable waveforms. The waveforms will range from large/coarse to small/fine. V-fib will not feature a P-wave, QRS complex, or T-wave.
Atrial Flutter with a 3 flutter wave to 1 QRS conduction A-flutter is very similar in nature to that of A-fib. Instead of merely quivering, instead the Atria are contracting very rapidly. This can also result in RVR. Additionally A-flutter can be regular or irregular. Before each QRS complex will be at least one flutter wave, sometimes many more. A flutter wave is similar to a P-wave except that often times there will be a varying amount of them.