How is internal synchronized electrical cardioversion administered?

Updated: Nov 28, 2018
  • Author: Sean C Beinart, MD, MSc, FACC, FHRS; Chief Editor: Jose M Dizon, MD  more...
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The success of internal defibrillation with low-energy shocks to treat ventricular fibrillation and ventricular tachycardia resulted in further studies of internal cardioversion for the treatment of atrial fibrillation. Note the following:

  • The patient should receive anticoagulation as for external cardioversion, although anticoagulation should be withheld for safe venous puncture. Various techniques are available; the following is a commonly used procedure.

  • Three temporary catheters are inserted in the venous system and positioned under fluoroscopic guidance. Two catheters of large surface area are used for shock delivery, and a third quadripolar catheter is used for R-wave synchronization and temporary ventricular postshock pacing. The first defibrillation catheter is advanced into the distal coronary sinus; the second is positioned in the right atrium appendix or the lateral wall of the right atrium. These catheters are connected to an external defibrillator that delivers biphasic shocks. The quadripolar catheter is placed in the apex of the right ventricle and is also connected to an external pacemaker. In a study, right atrium-to-coronary sinus cardioversion vector was successfully used with mean energy of 5.6 ± 4.7 joules (0.4-35 joules). [14]

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