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Figure 2 The figure shows the result of the adenosine triphosphate (ATP) test performed in Patient no. 2. Continuous tracings of the electrocardiogram and non-invasive blood pressure (BP) (Finapres method) are shown. The bolus of ATP causes abrupt third-degree atrioventricular (AV) block with long ventricular asystoles of 5.2, 6.0, and 4.5 s. The sinus rate increases during the block. Thus, the effect of the drug is limited to the AV conduction system. Systolic blood pressure dropped from an initial value of 140 mm Hg to values ranging between 80 and 110 mm Hg.