Question 8

R_0024

 

Describe the rhythms seen in the R_0024, which show rhythm strips before, during and after cardioversion

 

 

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Figure 1

Figure 1 shows Rhythm Strip A. The R-R intervals are shown at the top of the strip, and are between 520 and 560 msec (corresponding to a ventricular rate of 107 to 115 beats per minute).

There is a downward deflection before each QRS complex. Two of these deflections have been outlined in red in the upper strip. The downstroke is longer than the upstroke, and the deflection has a sawtooth appearance. In the lower strip the single highlighted deflection on the right has been used as a template to draw three more deflection. The fourth (derived) deflection matches the visible deflection before the next QRS complex. The four red deflections have a saw tooth shape, with no intervening isoelectric interval. This indicates that the atrial rhythm is atrial flutter, with an atrial rate of 300 to 350 beats per minute.

Rhythm Strip A shows atrial flutter with a 3:1 atrioventricular block Rhythm Strip B shows several ventricular ectopic beats immediately after cardioversion at 30 Joules, then a three second pause before cardiac activity resumes

Figure 2

Strip C in Figure 2 shows a junctional rhythm soon after cardioversion, with a ventricular rate that increases from 42 beats per minute to 52 beats per minute. Strip D shows sinus rhythm with a ventricular rate of 42 to 50 beats per minute

Important Points

  • Atrial flutter with 3:1 block
  • Junctional escape rhythm after cardioversion of the atrial flutter