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Dromotropic derives from the Greek word "dromos", meaning running, a course, a race. A dromotropic agent is one which affects the conduction speed (in fact the magnitude of delay) in the AV node, and subsequently the rate of electrical impulses in the heart.
Agents that are dromotropic are often (but not always) inotropic and chronotropic. For instance, parasympathetic stimulation is usually negatively chronotropic and dromotropic, but because the vagus nerve does not innervate ventricular myocardium has no effect on inotropy.
Non-dihydropyridine calcium channel blockers such as verapamil block the slow inward calcium current in cardiac tissues, thereby having a negatively dromotropic, chronotropic and inotropic effect. This (and other) pharmacological effect makes these drugs useful in the treatment of angina pectoris. Conversely, they can lead to symptomatic disturbances in cardiac conduction and bradyarrhythmias, and may aggravate left ventricular failure.