<prompt> All of the following cause myocardial depression except:HalothaneEtomidateThiopentoneKetamine  <response>: B i.e. Etomidate - Etomidate causes adreno - coical suppressionQ by inhibiting enzymes 113 hydroxylase mainly 17 a hydroxylase involved in coisol and aldosterone mineralocoicoid productionQ. Vit C supplimentation restores coisol level. - Etomidate and midazolam provide cardiovascular stabilityQ. But etomidate is most cardiostable agentQ that causes the least hemodynamic disturbance of any of the intravenous anesthetic agents. So it is intravenous anesthetic agent of choice for patients with cardiac disease and aneurysm surgeryQ. - Direct myocardial depression is caused by halothane severe, nitrous oxide moderate, isosevodes-flurane mild, thiopental marked, propofol dose dependent and ketamineQ but this is masked by cardiotonic sympathetic stimulatory action. Etomidate midazolem are most cardiostable agentsQ. 