Chronotropic effects (from ''chrono-'', meaning time, and ''tropos'', "a turn") are those that change the
heart rate.
Chronotropic
drugs
A drug is any chemical substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via inhalat ...
may change the
heart rate and
rhythm by affecting the
electrical conduction system of the heart and the
nerves that influence it, such as 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. A positive dromotrope increases AV nodal conduction, and a negative dromotrope decreases AV nodal conduction. A
lusitrope is an agent that affects diastolic relaxation.
Many positive
inotropes affect
preload and
afterload
Afterload is the pressure that the heart must work against to eject blood during systole (ventricular contraction). Afterload is proportional to the average arterial pressure. As aortic and pulmonary pressures increase, the afterload increases on ...
.
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Negative chronotropes
Chronotropic variables in systolic myocardial left and right. Left sided systolic chronotropy can be appreciated as Aortic Valve open to close time. Right sided variables are represented by pulmonary valve open to close time. Inverted as diastolic chronotropy, the variables are aortic valve close to open and pulmonic close to open time. Pharmaceutical manipulation of chronotropic properties was perhaps first appreciated by the introduction of
digitalis, though it turns out that digitalis has an
inotropic effect rather than a chronotropic effect.
*
Beta blockers such as
metoprolol
*
Acetylcholine
Acetylcholine (ACh) is an organic chemical that functions in the brain and body of many types of animals (including humans) as a neurotransmitter. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Part ...
*
Digoxin
Digoxin (better known as Digitalis), sold under the brand name Lanoxin among others, is a medication used to treat various heart conditions. Most frequently it is used for atrial fibrillation, atrial flutter, and heart failure. Digoxin is on ...
* Pacemaker current (i.e.
HCN channel) inhibitors (e.g.
ivabradine)
Positive chronotropes
* Most
Adrenergic agonists
*
Atropine
Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically given i ...
*
Dopamine
Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic compound, organic chemical of the catecholamine and phenethylamine families. Dopamine const ...
*
Epinephrine
Adrenaline, also known as epinephrine, is a hormone and medication which is involved in regulating visceral functions (e.g., respiration). It appears as a white microcrystalline granule. Adrenaline is normally produced by the adrenal glands and ...
*
Isoproterenol
*
Milrinone
*
Theophylline
Theophylline, also known as 1,3-dimethylxanthine, is a phosphodiesterase inhibiting drug used in therapy for respiratory diseases such as chronic obstructive pulmonary disease (COPD) and asthma under a variety of brand names. As a member of the ...
References
Cardiovascular physiology
Antiarrhythmic agents
{{cardiovascular-drug-stub