TACHYCARDIES VENTRICULAIRES SENSIBLES A L'ADENOSINE TRIPHOSPHATE CHEZ L'HOMME

Purinergic receptor agonists such as adenosine triphosphate (ATP) and adenosine are primarily used to treat supraventricular tachycardias (SVT). Nonetheless, both have been reported to terminate ventricular tachyarrhythmias (VT) in a few instances. This study attempted to characterise further those VT which may be amenable to termination by these agents. To this end, the effects of adenosine triphosphate (ATP) were evaluated in 8 VT patients (6 men, 2 women, age 40±19) without ischaemic heart disease. Clinical VT was inducible by programmed electrical stimulation in 6 of 8 patients and occurred spontaneously in the remaining two patients. ATP terminated VT in 5 patients (ATP-positive) and was ineffective in 3 patients (ATP-negative). The principal differences between ATP-positive and ATP-negative VT were; 1) VT exacerbation or induction by exercise testing in 3 of 5 ATP-positive patients versus none of 3 ATP-negative patients, 2) spontaneous VT onset or facilitation during isoprenaline infusion in 5 of 5 ATP-positive patients versus none of 3 ATP-negative patients, 3) a tendency toward parallel relation between S₁S₂ interval initiating tachycardia and the first S₂-'echo' coupling interval in ATP-positive tachycardias, 4) VT termination and/or prevention by verapamil in 4 of 5 ATP-positive patients versus one of 3 ATP-negative patients. 5) VT termination and/or prevention by propranolol in 5 of 5 ATP-positive versus none of 3 ATP-negative patients. Thus, our findings confirm previous reports that certain forms of VT are susceptible to termination by purinergic receptor agonists. Furthermore, they suggest that ATP-sensitive VT exhibits greater catecholamine and calcium (Ca⁺⁺)-influx sensitivity than does ATP-resistant VT, and may be predominantly due to triggered activity.