Pediatric emergency medicine trisk 1735 1735
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FIGURE 86.10 Bradycardia due to complete heart block. Note there is no association between
P waves and QRS complexes.
In all cases of symptomatic bradycardia the goal is to restore the rhythm and/or
rate to supply adequate cardiac output. Sometimes the heart rate can be increased
with the infusion of epinephrine. If this is not effective, emergency pacing must
be instituted. This may be achieved quickly by transthoracic pacing through the
external defibrillator device. Another option is transvenous temporary pacing.
For external pacing, the defibrillation pads are placed in position so that the
current passing between them will capture the ventricle. Typically, placement is to
the right of the sternum and on the left lateral chest. Beware of dextrocardia in
patients with CHD and place pads accordingly. Pacing is commenced at an age
appropriate rate with maximum output. Output may be adjusted down when
capture is confirmed, but an adequate safety margin is necessary. The patient
must be sedated and treated for pain. Pharmacologic neuromuscular blockade is
also recommended if external pacing is used for more than a few minutes. This
will eliminate contraction of the chest muscles and make capture easier to
recognize, but the patient will require mechanical ventilation. Transthoracic
pacing may be used as a bridge to temporary transvenous pacing.
For transvenous pacing, access to the RV via the right internal jugular,
subclavian, or femoral vein is obtained. Placement is best achieved in the
catheterization laboratory under fluoroscopic guidance. In the ED catheter
position is documented and confirmed with a CXR. The pacing catheter is
advanced to the RV and connected to an external pacemaker. This temporary
