Least effect on myocardial contractility

Ans:D i.e. Isoflurane. CARDIAC EFFECTS OF ANESTHETIC AGENTS :Anticholinergic agents - Atropine/glycopyrrolate: will cause an increase in hea rate, contractility, cardiac output and myocardial oxygen consumption. Often there will be no changein blood pressure and a decrease in right atrial pressure.Thiopental - BarbiturateReduction in blood pressure - peripheral vasodilation is the main action. Compensatory rise in hea rate - barorecptor response. Commonly associated with ventricular arrhythmias .BenzodiazepinesMidazolam and diazepam: Cause little or no direct myocardial depressant effects.Hypnotics- Etomidate: no direct myocardial depression. Safe to use with cardiac, critical and septic patients. .Mu opioids- Fentanyl is a pure mu agonist causes dose dependant bradycardia (increase in vagal tone). Mixed agonist/antagonist agents= Buprenorphine: a paial mu agonist/antagonist. Slow onset of action, duration of 6-8 hours. Cardiovascular depression and respiratory depression not as profound as pure mu agonists. Butorphanol: paial agonist/antagonist. Similar to buprenorphine in cardiovascular/respiratory effects. Dissociative Agents:Ketamine- Hea rate and aerial pressure increase due to an increase in sympathetic tone .Inhalational Anesthetics: Isoflurane and sevoflurane preserved cardiac index, and isoflurane and fentanyl-midazolam preserved myocardial contractility at baseline levels in this group of patients with congenital hea disease. Halothane depressed cardiac index and myocardial contractility.