Atrioventricular (AV) Blocks First Degree AV Block - "If your R is far from your P than you have a first degree" • 1:1 conduction with prolonged PR interval (>200 msec) • P wave preceding each QRS complex • Site of Block: Delayed conduction at the AV node Second Degree AV Block - Mobitz Type 1 (Weinckebach) - "Longer, longer, longer DROP, now you have a Weinckebach" • Less than 1:1 AV conduction with progressively prolonged PR intervals until a P wave (ventricular complex) is dropped • Site of Block: Slowed conduction at the AV node Second Degree AV Block - Mobitz Type 2 "If some P's don't get through, not you have a Mobitz Type 2" • Intermittently dropped QRS in a random fashion with progressive PR lengthening • Site of Block: Slowed conduction below AV node (His bundle or Purkinje Fibers) Third Degree AV Block - "If your P's and Q's don't agree, then you have a Third Degree" • Complete Heart Block • AV conduction is completely absent, P waves fail to conduct to the ventricles • Ventricle beats independently of the atria leading to AV node dissociation and the rate is set at the site of conduction block • Site of Block: Any location in AV conducting system (AV node, His Bundle, trifasicular) Ashley & Brooke Barlow PharmD @theABofPharmaC #Atrioventricular #AV #Blocks #heart #heartblock #cardiology #ecg #ekg #diagnosis #electrocardiogram
