Urgent considerations

See Differentials for more details

Cardiac arrest and hemodynamic instability: urgent cardioversion

Patients who suffer a cardiac arrest from ventricular fibrillation, polymorphic ventricular tachycardia (VT), or rapid VT require CPR and prompt defibrillation.[46] In this situation the chance of surviving the cardiac arrest decreases by 7% to 10% for every 1-minute delay in defibrillation.[47][48][49]

Atrial fibrillation with ventricular preexcitation often requires immediate cardioversion because of the risk that the arrhythmia will degenerate into ventricular fibrillation. Long term anticoagulation should be considered based on thromboembolic risk.[5]

In any situation where a tachycardia (regardless of the mechanism) is the cause of hemodynamic instability, angina, syncope, or decompensated heart failure, the priority should be toward rapid termination of the arrhythmia. In many cases (atrial fibrillation with rapid ventricular response, supraventricular tachycardia, VT) electrical cardioversion is the most efficient and reliable way to achieve sinus rhythm. It is useful to obtain a rhythm strip during and immediately after cardioversion in the event of reinitiation of the rhythm.[47][48]

Regular wide-complex or regular narrow-complex tachycardia with hemodynamic stability: adenosine administration

In patients who are stable with a regular wide- or narrow-complex tachycardia, administration of adenosine is a therapeutic intervention and can provide useful diagnostic information.[14]

Adenosine should be administered in a closely monitored setting, with the patient supine, and with continuous ECG and hemodynamic monitoring.

Adenosine is metabolized rapidly by red blood cells and must therefore be given as a rapid bolus to be effective.

Adenosine transiently slows the sinus node or atrial tachycardia and transiently slows or blocks conduction in the atrioventricular (AV) node. Depending on the arrhythmia mechanism, adenosine may unmask the underlying rhythm (atrial flutter, atrial tachycardia) or may terminate arrhythmias that are dependent on the AV node (AV nodal reentrant tachycardia, AV reciprocating tachycardia).

Caution is required in the presence of atrial fibrillation and a possible accessory conduction pathway because adenosine can precipitate preferential rapid accessory tract conduction and degeneration to ventricular fibrillation.

Use of this content is subject to our disclaimer