Congenital complete heart block – exercise response

Congenital complete heart block – exercise response

Congenital complete heart block
Congenital complete heart block

Congenital complete heart block with RR interval of 1280 ms (ventricular rate: 47/min) and PP interval of  960 ms (atrial rate of 62.5/min). The four criteria for diagnosis of complete heart block are satisfied: regular PP interval, regular RR interval, PP interval less than RR interval and varying PR interval. QRS is narrow, indicating supra Hisian location of the complete heart block, with a junctional focus capturing the ventricle. Such a situation in a young boy indicates congenital complete heart block. An exercise test is useful in assessing the response of the heart rate to exercise (below).

Congenital complete heart block - Stage 1 of exercise
Congenital complete heart block – Stage 1 of exercise

In stage 1 of exercise, the PP interval has shortened to 600 msec (atrial rate: 100/min) and RR interval is 1000 msec (ventricular rate: 60/min). There is progressive change in atrial and ventricular rates with exercise, though the response is blunted compared to sinus rhythm with regular conduction. (Please observe the raw rhythm strip at the bottom of the tracing). The peak exercise recording is given below.

Congenital complete heart block - peak exercise
Congenital complete heart block – peak exercise

Peak exercise tracing in congenital complete heart block with PP interval 400 msec (atrial rate: 150/min) and RR interval of 720 msec (ventricular rate: 83/min). (Please observe the raw rhythm strip at the bottom of the tracing).

Ikkos D et al have reported the response to exercise of 11 patients with congenital complete heart block in the age range of 7 to 23 years [1]. They noted similar difference in the exercise response between atrial and ventricular rates. While the atrial rate was between 160 to 185/min in the second workload on bicycle ergometry, ventricular rate was between 68-130/min.

In another study, in 8 patients aged 8-17 years, ventricular rate was between 36 to 56 beats/min at rest and increased to a mean value of 106 +/- 25 on exercise [2]. Blank AC et al evaluated 16 children with congenital complete heart block, 13 of whom had received pacemakers [3]. They documented that paced children did not perform better on exercise tolerance test compared to the those who were not paced. 25% of paced patients showed upper rate restriction by the pacemaker. This was despite an average programmed pacemaker upper rate of 182 ± 11 bpm.

References

  1. Ikkos D, Hanson JS. Response to exercise in congenital complete atrioventricular block. Circulation. 1960 Oct;22:583-90.
  2. Reybrouck T, Vanden Eynde B, Dumoulin M, Van der Hauwaert LG. Cardiorespiratory response to exercise in congenital complete atrioventricular block. Am J Cardiol. 1989 Oct 15;64(14):896-9.
  3. Blank AC, Hakim S, Strengers JL, Tanke RB, van Veen TA, Vos MA, Takken T. Exercise capacity in children with isolated congenital complete atrioventricular block: does pacing make a difference? Pediatr Cardiol. 2012 Apr;33(4):576-85.