Milrinone

How it works

By inhibiting phosphodiesterase-3 it raises intracellular cyclic AMP in cardiac and vascular smooth muscle, increasing myocardial contractility and causing peripheral and pulmonary vasodilatation, thereby augmenting cardiac output while reducing filling pressures.

Prescribing in practice

• It can cause ventricular and supraventricular arrhythmias and hypotension, so it must be given with continuous cardiac and blood-pressure monitoring in a monitored environment.
• It is renally cleared, so the infusion rate must be reduced in renal impairment to avoid accumulation and toxicity.
• As a vasodilator it should be used cautiously in hypovolaemia or severe outflow obstruction, where it can precipitate marked hypotension.

Monitoring

Use continuous ECG, blood pressure and fluid-balance monitoring, with attention to renal function and electrolytes during the infusion.

Counselling the patient

• This is a drip given and closely monitored by the critical-care or cardiology team.
• The team will watch your heart rhythm and blood pressure continuously while it is running.
• Tell the team if you feel palpitations, lightheaded or unwell during the infusion.

Evidence & guidelines

Milrinone is an established short-term inotrope for acute decompensated heart failure; intravenous inotropes are reserved for low-output states and have not been shown to improve long-term survival.