Adrenergic stimulation is well known for having an important role in the induction of ventricular arrhythmias in different arrhythmogenic cardiomyopathies. Adrenaline, a non-selective β-adrenergic agonist, is commonly used in the provocative test to induce ventricular arrhythmias sensitive to catecholamines. The test can serve as an additional diagnostic tool for the early identification of patients at risk of malignant arrhythmias, for example in patients with suspected arrhythmogenic heart disease and long QT syndrome, even if the prognostic significance of this test is not yet fully clarified. The adrenaline test is also performed in patients with a history of supraventricular and ventricular arrhythmias after transcatheter ablation, to exclude the inducibility of arrhythmias after ablation.
The adrenaline test is performed after the interruption of β-blockers, calcium channel blockers and other antiarrhythmic agents for ≥ 5 half-lives. The test is carried out in the electrophysiology room, in the presence of suitable personnel and equipment for cardiopulmonary resuscitation. The test is generally practiced in the context of an electrophysiological study. A continuous infusion of Adrenaline is practiced according to the dosages and infusion rate established on the basis of the weight and pathology of the patient under examination (see attached diagrams). The 12-lead ECG tracing is recorded continuously from the start of the infusion until at least 10 minutes after the cessation of the infusion.
The test is considered positive if a monomorphic or polymorphic VT is sustained during the test or within 10 minutes from the end of the infusion. The infusion is immediately stopped if the test is positive and, in the case of VT, an electrical cardioversion is performed or a β-blocker is injected intravenously.
During the test, the assessment of the duration of the QT interval is also carried out, corrected for heart rate according to Bazett’s formula. QTc values > 480 msec are considered pathological (to be correlated to the clinical parameters of the individual patient).
The adrenaline test is performed to evaluate the inducibility of potentially serious and fatal arrhythmias. The risk of the Adrenaline test is, however, very controlled, and is carried out in the presence of suitable personnel and equipment for cardiopulmonary resuscitation in case of the need for the immediate treatment of any evoked arrhythmia. The risk is commensurate with the need to know the risk of developing serious arrhythmias in the individual patient.