cardiac contractility question?

Barbiturate mechanism of action:

http://en.wikipedia.org/wiki/Barbituate#Mechanism_...

Barbiturates act on the GABAa receptors to prolong the action of GABA. GABA is the principal inhibitory neurotransmitter in the CNS. So it's inhibiting or decreasing all sorts of actions in the brain including cardiac function and respiration. Increasing GABA also decreases the release of glutamate which is an excitatory neurotransmitter in the CNS. This leads to further inhibition of CNS mediated function including cardiac and pulmonary function. So basically, barbiturates make the CNS send fewer signals to the heart resulting in decreased contractility.

Common causes of cardiomyopathy are:

* Alcoholism and cocaine use

Due to decreased contractibility, the end systolic volume will be higher and the ejection fraction will be less.

The outlook depends on many different things, including:

* Severity of the heart problem

* Type of cardiomyopathy

* Cause of the cardiomyopathy

* How well you respond to treatment

The disorder is long-term (chronic) and the condition may get worse very quickly.