General

1. Check threshold daily as it will rise slowly over 48-96h, probably due to fibrosis occurring around the electrodes.

2. Overpacing is occasionally indicated for a tachycardia not responding to antiarrhythmic therapy or cardioversion. For SVT, pacing is usually attempted with the wire sited in the right atrium. Pace at rate 20-30bpm above patient's heart rate for 10-15s, then either decrease rate immediately to 80bpm or slowly, by 20bpm every 5-10s.

3. If overpacing fails, underpacing may be attempted with the wire situated in either atrium (for SVT) or, usually, ventricle (for either SVT or VT). A paced rate of 80-100bpm may produce a refractory period sufficient to suppress the intrinsic tachycardia.

4. Epicardial pacing performed during cardiac surgery requires siting of either two epicardial electrodes or one epicardial and one skin electrode (usually a hypodermic needle). The pacing threshold of epicardial wires rises quickly and may become ineffective after 1-2 days.

5. In asystole, an electrical rhythm produced by pacing does not guarantee an adequate cardiac output is being generated.

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