Jump to navigation Jump to search

WikiDoc Resources for Contractility


Most recent articles on Contractility

Most cited articles on Contractility

Review articles on Contractility

Articles on Contractility in N Eng J Med, Lancet, BMJ


Powerpoint slides on Contractility

Images of Contractility

Photos of Contractility

Podcasts & MP3s on Contractility

Videos on Contractility

Evidence Based Medicine

Cochrane Collaboration on Contractility

Bandolier on Contractility

TRIP on Contractility

Clinical Trials

Ongoing Trials on Contractility at Clinical

Trial results on Contractility

Clinical Trials on Contractility at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on Contractility

NICE Guidance on Contractility


FDA on Contractility

CDC on Contractility


Books on Contractility


Contractility in the news

Be alerted to news on Contractility

News trends on Contractility


Blogs on Contractility


Definitions of Contractility

Patient Resources / Community

Patient resources on Contractility

Discussion groups on Contractility

Patient Handouts on Contractility

Directions to Hospitals Treating Contractility

Risk calculators and risk factors for Contractility

Healthcare Provider Resources

Symptoms of Contractility

Causes & Risk Factors for Contractility

Diagnostic studies for Contractility

Treatment of Contractility

Continuing Medical Education (CME)

CME Programs on Contractility


Contractility en Espanol

Contractility en Francais


Contractility in the Marketplace

Patents on Contractility

Experimental / Informatics

List of terms related to Contractility

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]


Myocardial Contractility is a term used in physiology to describe the performance of cardiac muscle. It is often defined as: the intrinsic ability of a cardiac muscle fibre to contract at a given fibre length.

Determinants of Myocardial Contractility

The five determinants of myocardial performance are:

If myocardial performance changes while preload, afterload, heart rate, and conduction velocity are all constant, then the change in performance must be due to the change in contractility.

It might be thought that a better definition would be that Contractility is the property that represents the strength of myocardial contraction. However, this definition does not separate contractility from the other loading factors that affect the strength of myocardial contraction. In particular, an increase in preload results in an increased force of contraction - this is Starling's law of the heart - but this does not require a change in contractility.

Any chemicals that affects contractility is called inotropic agent. For example drugs such as catecholamines (norepinephrine and epinephrine) that enhance contractility are considered to have a positive inotropic effect.

The concept of Contractility was necessary to explain why some interventions (e.g. an adrenaline infusion) could cause an increase in myocardial performance even if, as could be shown in experiments, the preload, afterload and heart rate were all held constant. Experimental work controlling the other factors was necessary because a change in contractility is generally not an isolated effect.

For example:

  • An increase in sympathetic stimulation to the heart increases contractility AND heart rate.
  • An increase in contractility tends to increase stroke volume and thus a secondary increase in preload.

All factors that cause an increase in contractility work by causing an increase in intracellular [Ca++] during contraction.


Template:WikiDoc Sources