Temporary Transvenous Pacemaker Placement by Intracavitary Electrocardiogram Monitoring

Traditional temporary pacing catheter insertion by intracavitary electrocardiogram (IC-ECG) monitoring which only monitoring tip polar, the negative one. The investigators modified the technique by monitoring both negative and positive polar which will be precisely locating catheter tip and indicating the direction of the catheter tip. Extensively used temporary pacing catheter tip has two electrodes which are about 1 cm apart. Distal electrode is negative (-) and active, proximal electrode is positive (+) and indifferent. Investigators use both distal (-) and proximal (+) electrodes which can be attached to any two of the V leads, record as V(-) and V(+). Monitoring positions of the electrodes by V(-) and V(+) could provide more information about the tip position. Comparing the QRS amplitudes between V(-) and V(+), when catheter tip enters right ventricle chamber: the case of V(-) \> V(+) infers tip toward apex ventricle wall ; conversely, the case of V(-)\<V(+) indicates tip directs to outflow tract. The investigators hypothesis this monitoring will help precisely placement.