What are the contraindications for cardiac electrical cardioversion?

Contraindications for cardiac electrical cardioversion generally include patients with critical and unstable conditions, atrial fibrillation, digitalis toxicity, etc. Specific situations are as follows:

1. Critical and unstable condition

For patients with severe heart failure or serious electrolyte disturbances, performing electrical cardioversion may exacerbate the harm caused by their underlying diseases.

2. Atrial fibrillation

Atrial fibrillation typically occurs with increasing age, with atrial activation rates reaching 300–600 beats per minute. It may cause palpitations, worsen myocardial ischemia, and lead to decreased cardiac function. Performing electrical cardioversion in such cases may easily dislodge cardiac thrombi and increase the risk of stroke.

3. Digitalis toxicity

Digitalis reduces the automaticity of the sinoatrial node, slows sinus rate, prolongs the effective refractory period of the atrioventricular node, and decreases conduction velocity. Performing electrical cardioversion at this time may induce ventricular fibrillation.

In addition to the above contraindications, electrical cardioversion is also prohibited in patients during active rheumatic phase, acute phase of myocarditis, or acute infection. If any discomfort occurs, prompt medical treatment at a hospital is required.