mechanism of action of inotropes

1. ionotropes
Dre.srinivasan

2. MILRINONE
Pde 3 inhibitor
Inodilator – inotropic and vasodilator
Pde 3 inhibition increase camp
Lusiotropic – myocardial relaxation

3. • Increase cardiac output
• Decrease svr and pvr
• Reduction in systemic blood pressure
• Decreased myocardial o2 demand
• Should be used along with a agonist to
maintain bp like phenylephrine or noradr

4. • The increase in cardiac output is comparable
to dobutamine
• Dobutamine is associated with increase in
heart rate and increased incidence of atrial
and ventricular arrhythmias
• And increased myocardial o2 demand

5. INDICATION
• Low cardiac output
• Rv dysfunction with increased pvr as in mitral
stenosis
• In CABG patient to prevent graft spasm
• Half life 1 – 2 hrs , increased t1/2 in chf and
low cardiac output states
• Dosing 50 mcg /kg bolus , infusion 0.375 –
0.75 mcg/kg/min

6. LEVOSIMENDAN
• Calcium sensitizer – binds to calcium troponin
c complex
• Opens ATP sensitive k channel – vasodilator
• Mitochondrial ATP sensitive k channel –
cardioprotective
• lusiotropic

7. • Svr and pvr decreased
• Reduce both preload and afterload
• Improves coronory perfusion
• Heart rate is not increased
• Myocardial o2 demand not increased
• Anti stunning – calcium homeostasis and
decreased sensitivity of contractile proteins to
calcium

8. INDICATION
• Post cardiotomy rv and lv dysfunction
• To wean from bypass
• Rv dysfunction – decrease pvr and improves rv
contractility
• Infusion started prior to bypass to prevent
troponin leakage
• Half life 70 – 80 hrs
• Dosing 12 – 24 mcg /kg bols , infusion 0.05 –
0.2 mcg / kg /min

9. ISOPROTERENOL
• B 1 agonist – increase rate , increase cardiac
output and myocardial o2 demand and
predispose to ventricular arrhythmias
• B2 agonist – reduce pvr and rv afterload
• Bronchodilator

10. INDICATION
• Rv dysfunction in cases of mitral stenosis , to
reduce rv contractility and reduce pvr
• In copd patients
• In cardiac transplant patient to maintain heart
rate 100 – 110
• Dosing 0.0075 – 0.1 mcg/kg/min