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.A dromotrope affects atrioventricular node (AV node) conduction.