Dromotropia

Dromotropia refers to the influence of substances on the speed of conduction of the electrical impulse through the cardiac conduction system. This system is responsible for initiating and coordinating the heart's contractions. The term is derived from the Greek words "dromos" meaning running or speed, and "tropos" meaning turning or influence. In pharmacology, dromotropia is a key property considered when evaluating the effects of drugs on the heart, particularly those used to treat arrhythmias or other cardiac conditions.

Positive dromotropia indicates an increase in the speed of conduction, meaning the electrical impulse travels faster through the heart. Conversely, negative dromotropia signifies a decrease in conduction speed. This effect is most commonly observed and clinically significant in the atrioventricular (AV) node, a critical junction in the conduction pathway. For example, some medications can slow conduction through the AV node to prevent rapid ventricular rates in conditions like atrial fibrillation. The sinoatrial (SA) node and the His-Purkinje system are also subject to dromotropic influences, though the AV node is often the primary focus. Understanding dromotropic effects is crucial for predicting a drug's efficacy and potential side effects in cardiovascular medicine.