Junctional and idioventricular rhythm

Question 1

If there is no P wave present what does this indicate?

Answer 1

2 causes:
* Ectopic beat (will generally produce a higher rate than junctional beat)
* Junctional beat (from AVN): produces a rate of 40-60/min (can also produce retrograde p wave hidden in QRS complex)

Question 2

Answer 2

ECG strip (10 secs) = 300/6 =50 beats/ min
lead II (6 secs): 9 x 10 = 90 beats/min

No P wave present in both aVR and lead II. If no P wave present = not sinus rhythm (hence =ectopic or junctional rhythm)
As there is no P wave there cannot be association between P and QRS wave = AV dissociation
QRS wave = wide complex QRS = more likely junctional rhythm

This is a case of SAN failure and the AVN taking over.

Question 3

Answer 3

Idioventricular rhythm (when both the SAN and AVN failure –> rely on Purkinje fibers for pacemaker)

2 ways of calculating rate
If 6 secs strip = number of R wave x 10. 4=10 =40bpm
300/number of small little boxes = 300/8 = 38bpm

Rhythm
R-R is regular
P wave: none
P–> QRS: no P wave so AV dissociation
QRS: wide QRS (more than 3 small little boxes –> similar appearance to PVC)