Agent that alters the strength of muscular contractions
An
inotrope
[help 1]
or
inotropic
is a
drug
or any substance 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
inotropic state
is most commonly used in reference to various
drugs
that affect the strength of
contraction of heart muscle
. However, it can also refer to
pathological
conditions. For example,
enlarged heart muscle
can increase inotropic state, whereas
dead heart muscle
can decrease it.
Medical uses
[
edit
]
Both positive and negative inotropes are used in the management of various cardiovascular conditions. The choice of agent depends largely on specific pharmacological effects of individual agents with respect to the condition. One of the most important factors affecting inotropic state is the level of
calcium
in the
cytoplasm
of the muscle cell. Positive inotropes usually increase this level, while negative inotropes decrease it. However, not all positive and negative drugs affect calcium release, and, among those that do, the mechanism for manipulating the calcium level can differ from drug to drug.
While it is often recommended that
vasopressors
are given through a
central line
due to the risk of local tissue injury if the medication enters the local tissues, they are likely safe when given for less than two hours through good peripheral
intravenous catheterization
.
[6]
Positive inotropic agents
[
edit
]
By increasing the concentration of intracellular
calcium
or increasing the sensitivity of receptor proteins to calcium, positive inotropic agents can increase
myocardial contractility
.
[7]
Concentrations of intracellular calcium can be increased by increasing influx into the cell or stimulating release from the sarcoplasmic reticulum.
[8]
Once in the cell, calcium can pass through one of two channels: the
L-type calcium channel
(long-lasting) and the
T-type calcium channel
(transient). These channels respond to voltage changes across the membrane differently: L-type channels respond to higher membrane potentials, open more slowly, and remain open longer than T-type channels.
Because of these properties, L-type channels are important in sustaining an
action potential
, while T-type channels are important in initiating them.
[9]
By increasing intracellular calcium, via the action of the L-type channels, the action potential can be sustained for longer and therefore, contractility increases.
Positive inotropes are used to support cardiac function in conditions such as
decompensated
congestive heart failure
,
cardiogenic shock
,
septic shock
,
myocardial infarction
,
cardiomyopathy
, etc.
[10]
Examples of positive inotropic agents include:
[
citation needed
]
Negative inotropic agents
[
edit
]
Negative inotropic agents decrease myocardial
contractility
and are used to decrease cardiac workload in conditions such as
angina
. While negative inotropism may precipitate or exacerbate heart failure in the short term, certain beta blockers (e.g.
carvedilol
,
bisoprolol
and
metoprolol
) have been believed to reduce long-term
morbidity
and
mortality
in
congestive heart failure
.
[13]
Examples of negative inotropic agents include:
Class IA
antiarrhythmics
such as
Class IC antiarrhythmics such as
See also
[
edit
]
Notes
[
edit
]
- ^
The word
inotrope
is
ISV
via
Neo-Latin
, from Greek
in
-, fibre or sinew, plus
-trope
, turning or moving. The prevalent pronunciations are
[1]
[2]
and
,
[3]
[4]
with
[2]
[5]
being less common.
References
[
edit
]
- ^
"Inotrope"
.
Merriam-Webster's Collegiate Dictionary
. Merriam-Webster.
- ^
a
b
"Inotrope"
.
The American Heritage Dictionary of the English Language
. Houghton Mifflin Harcourt.
- ^
"Inotrope"
.
Dorland's Illustrated Medical Dictionary
. Elsevier.
- ^
"Inotrope"
.
Stedman's Medical Dictionary
. Wolters Kluwer.
- ^
"Inotrope"
.
Merriam-Webster's Medical Dictionary
.
- ^
Loubani OM, Green RS (June 2015). "A systematic review of extravasation and local tissue injury from administration of vasopressors through peripheral intravenous catheters and central venous catheters".
Journal of Critical Care
.
30
(3): 653.e9?653.17.
doi
:
10.1016/j.jcrc.2015.01.014
.
PMID
25669592
.
- ^
Gordon S, Saunders A (November 2015).
"Positive Inotropes"
.
The Merck Veterinary Manual
. Retrieved
2016-11-28
.
- ^
Berry W, McKenzie C (January 2010).
"Use of inotropes in critical care"
.
Clinical Pharmacist
.
2
: 395
. Retrieved
2016-11-28
.
- ^
Sherwood L (2008).
Human Physiology, From Cells to Systems
(7th ed.). Cengage Learning.
ISBN
9780495391845
.
- ^
Oba Y, Lone NA (October 2014). "Mortality benefit of vasopressor and inotropic agents in septic shock: a Bayesian network meta-analysis of randomized controlled trials".
Journal of Critical Care
.
29
(5): 706?710.
doi
:
10.1016/j.jcrc.2014.04.011
.
PMID
24857641
.
- ^
Hu Y, Wei Z, Zhang C, Lu C, Zeng Z (December 2021).
"The effect of levosimendan on right ventricular function in patients with heart dysfunction: a systematic review and meta-analysis"
.
Scientific Reports
.
11
(1): 24097.
Bibcode
:
2021NatSR..1124097H
.
doi
:
10.1038/s41598-021-03317-5
.
PMC
8677770
.
PMID
34916560
.
- ^
Schror K, Hohlfeld T (1992). "Inotropic actions of eicosanoids".
Basic Research in Cardiology
.
87
(1): 2?11.
doi
:
10.1007/BF00795384
.
PMID
1314558
.
S2CID
29440212
.
- ^
Xu T, Huang Y, Zhou H, Bai Y, Huang X, Hu Y, et al. (June 2019).
"β-blockers and risk of all-cause mortality in patients with chronic heart failure and atrial fibrillation-a meta-analysis"
.
BMC Cardiovascular Disorders
.
19
(1): 135.
doi
:
10.1186/s12872-019-1079-2
.
PMC
6547467
.
PMID
31159740
.
- ^
Chatterjee S, Biondi-Zoccai G, Abbate A, D'Ascenzo F, Castagno D, Van Tassell B, et al. (January 2013).
"Benefits of β blockers in patients with heart failure and reduced ejection fraction: network meta-analysis"
.
BMJ
.
346
(jan16 1): f55.
doi
:
10.1136/bmj.f55
.
PMC
3546627
.
PMID
23325883
.