Question 7

R_0023

Describe the rhythms seen in R_0023, which were taken before and after the administration of streptokinase to a diabetic man with an acute ST segment elevation myocardial infarct

 

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Figure 1

Figure 1 is a laddergram analysis of Rhythm Strip A. There are 7 numbered complexes which can be grouped into:

  • Complex 1: Sinus beat
  • Complex 4: Ventricular ectopic beat
  • Complexes 3, 5 to 7. Junctional ectopic beats with R-R intervals of 1080 to 1120 msec (corresponding to a ventricular rate of 54 to 59 beats per minute.) Each of these complexes is followed by a low amplitude and broad based upward deflection that could be a U wave or a retrograde P wave ( indicated by ? in complex 5)

Figure 2

Figure 2 is a laddergram analysis of Rhythm Strip B, with 16 numbered complexes.

  • Black circles in the atrial tier mark visible P waves that precede the QRS complexes, and open circles mark the position of P waves with the same P-P interval that are obscured by QRS complexes. The atrial rate is about 58 beats per minute.
  • Complexes 2, 4 and 5 are normally conducted sinus beats. These complexes have changes consistent with an acute myocardial infarction (a very small Q wave, an elevated ST segment and a biphasic T wave)
  • Complex 11 is a ventricular ectopic beat
  • Complexes 7, 8 and 10 are fusion beats between sinus beats and ventricular ectopic beats
  • Complexes 3, 6, 9, 12 and 16 probably originate in the atrioventricular node arise or the bundle of His
  • Complexes 13 to 16 are three consecutive ventricular ectopic beats with a R-R interval of 920 seconds that corresponds to a ventricular rate of 65 beats per second

Figure 3

Figure 3 is a laddergram analysis of Rhythm Strip C which shows 10 consecutive beats that have a ventricular origin and an R-R interval of 720 - 760 msec, corresponding to a ventricular rate of 79 to 83 beats per minute. This is an accelerated idioventricular rhythm.

Important Points

  • Acute myocardial infarction is present
  • The atrial rate is about 58 beats per minute. Some of the atrial beats are conducted normally, others form fusion beats with complexes that have a ventricular origin, and there are periods of atrioventricular dissociation
  • There are junctional ectopic beats, and a junctional rhythm at rate of 54 to 59 beats per minute in Rhythm Strip A
  • Fusion beats are seen in Rhythm Strip B
  • Accelerated idioventricular rhythm at a rate of 65 to 83 beats per minute. This is a common finding during thrombolysis of an acute myocardial infarct