[Non invasive exploration of ventricular tachycardia]

Complementary investigation of ventricular tachycardia requires the use of non-invasive techniques before treatment, before considering other methods. Non-invasive investigations are usually complementary. Signal averaged electrocardiography allows detection of after potentials, a sign of a reentry circuit. Twenty-four hour Holter monitoring and exercise testing may reveal ventricular arrhythmias which could induce tachycardia. They may also show a "trigger" of tachycardia such as the catecholamine factor which is particularly sensitive to exercise testing and Holter monitoring. The latter investigation also informs on the variability of the heart rate, the disappearance of which is an argument in favour of the risk of sudden death. Holter recording and exercise testing should also be repeated after starting antiarrhythmic treatment to control the efficiency and detect possible proarrhythmogenic effects. The problem with these investigations is that they lack sensitivity as they are sometimes normal in patients with documented VT or lack specificity, ventricular arrhythmias being common and often without clinical significance.