The term ''dromotropic'' derives from the Greek word δρόμος ''drómos'', 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
The atrioventricular node or AV node electrically connects the heart's atria and ventricles to coordinate beating in the top of the heart; it is part of the electrical conduction system of the heart. The AV node lies at the lower back section of t ...
, and subsequently the rate of electrical impulses in the heart.
Positive dromotropy increases
conduction
Conductor or conduction may refer to:
Music
* Conductor (music), a person who leads a musical ensemble, such as an orchestra.
* Conductor (album), ''Conductor'' (album), an album by indie rock band The Comas
* Conduction, a type of structured f ...
velocity (e.g.
epinephrine stimulation), negative dromotropy decreases velocity (e.g.
vagal stimulation).
Agents that are dromotropic are often (but not always)
inotropic
An inotrope is an agent that alters the force or energy of muscular contractions. Negatively inotropic agents weaken the force of muscular contractions. Positively inotropic agents increase the strength of muscular contraction.
The term ''inotro ...
and
chronotropic
Chronotropic effects (from ''chrono-'', meaning time, and ''tropos'', "a turn") are those that change the heart rate.
Chronotropic drugs may change the heart rate and rhythm by affecting the electrical conduction system of the heart and the ner ...
. For instance,
parasympathetic stimulation is usually negatively chronotropic and dromotropic, but because the vagus nerve does not innervate ventricular myocardium, there is no effect on inotropy.
Non-dihydropyridine
calcium channel blockers such as
verapamil
Verapamil, sold under various trade names, is a calcium channel blocker medication used for the treatment of high blood pressure, angina (chest pain from not enough blood flow to the heart), and supraventricular tachycardia. It may also be ...
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
Bradycardia (also sinus bradycardia) is a slow resting heart rate, commonly under 60 beats per minute (BPM) as determined by an electrocardiogram. It is considered to be a normal heart rate during sleep, in young and healthy or elderly adults, a ...
, and may aggravate
left ventricular failure
Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, an ...
.
See also
*
Bathmotropic Bathmotropic often refers to modifying the degree of excitability specifically of the heart; in general, it refers to modification of the degree of excitability (threshold of excitation) of musculature in general, including the heart. It especiall ...
*
Inotrope
An inotrope is an agent that alters the force or energy of muscular contractions. Negatively inotropic agents weaken the force of muscular contractions. Positively inotropic agents increase the strength of muscular contraction.
The term ''inot ...
*
Catecholamines
References
{{Cardiovascular physiology
Cardiovascular physiology