1) Cardiovascular physiology 
Chronotropic effects (from chrono-, meaning time, and tropos, `a turn`) are those that change the heart rate. Chronotropic drugs may change the heart rate by affecting the nerves controlling the heart, or by changing the rhythm produced by the sinoatrial node. Positive chronotropes increase heart rate; negative chronotropes decrease heart rate. .....
(chrono- + Gr. tropikos turning) affecting the time or rate, as the rate of contraction of the heart.
<pharmacology> Affecting the time or rate, as the rate of contraction of the heart. ... Origin: Gr. Tropikos = turning ... (18 Nov 1997) ... 
(kron″o-tro´pik) affecting the time or rate.
Type: Term Pronunciation: kron′ō-trop′ik Definitions: 1. Affecting the rate of rhythmic movements (heartbeat).
chronotropic Affecting the rate of rhythmic movements; such as, the rate of contractions of the heart.
affecting the rate or timing of a physiologic process, as the heart rate.