using a new method for long-term recording of monophasic action potentials from the human heart , we studied in 17 patients the effects on ventricular action potential duration ( apd ) of three clinically pertinent cycle length perturbations : ( 1 ) single extrastimuli , ( 2 ) abrupt sustained rate acceleration and deceleration , and ( 3 ) different steady-state cycle lengths .
C0018787
heart
C0018827
ventricular