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Internal transvenous low energy cardioversion for the treatment of cardiac arrhythmias
Insights
Low energy endocardial cardioversion showed limited success in treating various arrhythmias, with significant patient discomfort reported. This method was effective for atrioventricular tachycardia and some ventricular tachycardia cases but not atrial arrhythmias.
Area of Science:
- Cardiology
- Electrophysiology
Background:
- Arrhythmias pose a significant clinical challenge.
- Cardioversion is a common treatment modality for arrhythmias.
Purpose of the Study:
- To evaluate the efficacy and patient tolerance of low energy endocardial cardioversion for diverse arrhythmias.
Main Methods:
- A pacing lead with large surface area electrodes was used with a low energy defibrillator.
- 23 patients with 30 arrhythmias (atrial flutter, atrial fibrillation, AV nodal tachycardia, AV re-entrant tachycardia, ventricular tachycardia, ventricular fibrillation) were treated.
Main Results:
- Successful cardioversion was achieved in atrioventricular tachycardia (2/2) and ventricular tachycardia (8/13).
- Atrial flutter (1/4), atrial fibrillation, and AV nodal tachycardia were not successfully terminated.
- Adverse events included induced arrhythmias and significant patient discomfort.
Conclusions:
- Low energy endocardial cardioversion has variable success rates and can cause considerable patient discomfort.
- Further optimization of electrode design and pulse waveforms is needed for improved efficacy and tolerance.
Abstract:
Low energy endocardial cardioversion was attempted in 23 patients with 30 arrhythmias, of whom only four were receiving additional drug treatment. Four had atrial flutter, five atrial fibrillation, three intra-atrioventricular nodal tachycardia, two atrioventricular re-entrant tachycardia, 13 ventricular tachycardia, and three ventricular fibrillation. A pacing lead with special large surface area electrodes--the active electrode positioned either in the right atrium or in the right ventricular apex and the indifferent electrode in the right atrium, superior vena cava, or inferior vena cava--was used together with a low energy defibrillator. A total of 114 shocks was delivered, 26 of which were atrial. One episode of atrial flutter was terminated, but atrial fibrillation and atrioventricular nodal tachycardia were not terminated in any of the patients. Both patients with atrioventricular tachycardia were successfully treated, as were eight of the patients with ventricular tachycardia. Atrial fibrillation was produced in three patients and non-sustained ventricular tachycardia in one, ventricular tachycardia was accelerated in two, and ventricular fibrillation induced in five. Fourteen patients experienced severe discomfort and seven mild or moderate discomfort, and only one found the procedure painless. One patient was anaesthetised throughout the procedure. Low energy endocardial cardioversion is not universally successful even at the highest energies tolerable, and with the present electrode and pulse waveforms some patients may suffer considerable discomfort.