Milrinone Dosing for Right Heart Failure
For right heart failure, administer milrinone as a 50 mcg/kg loading dose over 10 minutes, followed by a continuous infusion of 0.375-0.75 mcg/kg/min, with careful attention to avoiding systemic hypotension through slower bolus administration or omitting the loading dose in hypotensive patients. 1, 2
Standard Dosing Protocol
Loading Dose
- 50 mcg/kg administered slowly over 10 minutes 1
- Critical modification for RHF: Consider dividing the bolus into five equal aliquots administered over 10 minutes each if blood pressure stability is a concern, as systemic hypotension is the most common adverse effect 2
- Omit the loading dose entirely if systolic blood pressure <100 mmHg and begin directly with maintenance infusion 2, 3
Maintenance Infusion
- Standard rate: 0.5 mcg/kg/min (0.77 mg/kg total daily dose) 1
- Range: 0.375-0.75 mcg/kg/min based on hemodynamic response 1
- Maximum: 0.75 mcg/kg/min (1.13 mg/kg total daily dose) 1
- Dilute to 200 mcg/mL concentration using 0.45% NaCl, 0.9% NaCl, or 5% dextrose 1
Specific Advantages for Right Heart Failure
Milrinone is particularly effective in RHF due to its balanced effects on both cardiac contractility and pulmonary vascular resistance. 2
- Produces concomitant decline in pulmonary artery pressure, pulmonary wedge pressure, and both systemic and pulmonary vascular resistance 2
- Has neutral or beneficial effects on pulmonary vascular resistance, making it preferable in patients with pulmonary arterial hypertension 2
- Maintains full efficacy even in patients on beta-blocker therapy, as its mechanism of action is distal to beta-adrenergic receptors 2, 4
Renal Dose Adjustment
Reduce infusion rates in patients with renal impairment, as milrinone is 83% renally eliminated: 1, 5
- CrCl 50 mL/min: 0.43 mcg/kg/min 1
- CrCl 40 mL/min: 0.38 mcg/kg/min 1
- CrCl 30 mL/min: 0.33 mcg/kg/min 1
- CrCl 20 mL/min: 0.28 mcg/kg/min 1
- CrCl 10 mL/min: 0.23 mcg/kg/min 1
Critical Monitoring Requirements
Close hemodynamic monitoring is mandatory during milrinone administration: 2
- Target mean arterial pressure ≥65 mmHg 2
- Monitor cardiac output, pulmonary artery pressures, and systemic vascular resistance continuously 1, 6
- Discontinue immediately at first sign of arrhythmia or hypotension from excessive vasodilation 2
- Expect hemodynamic improvement within 15 minutes of starting infusion 6
Management of Hypotension
If hypotension occurs during milrinone infusion: 2
- Reverse with titrated boluses of isotonic crystalloid or colloid 2
- Consider initiating norepinephrine or vasopressin to overcome hypotension-related toxicity 2
- Co-administer vasopressors proactively in patients with low filling pressures to maintain systemic vascular resistance 2
Clinical Efficacy in RHF
Milrinone produces rapid and sustained hemodynamic improvement in right heart failure: 7, 6
- Significant decreases in right atrial pressure and pulmonary wedge pressure within 15 minutes 7, 6
- Cardiac index increases by 21-31% depending on dose (0.25-0.75 mcg/kg/min) 6
- Pulmonary artery occlusion pressure decreases by 13-41% in dose-dependent fashion 6
- Hemodynamic improvement sustained during 24-hour continuous infusion 7
Important Caveats
Milrinone should NOT be used for long-term therapy outside of palliative care or bridge to transplant, as it may increase mortality. 2, 4
- Inotropic agents are not recommended unless the patient is symptomatically hypotensive or hypoperfused due to safety concerns 4
- Most common adverse effects include ventricular arrhythmias (12%) and supraventricular arrhythmias (4%) 5
- Elimination half-life ranges from 1-10 hours depending on organ function, meaning 3-30 hours to reach steady state without loading dose 2
- Milrinone has synergistic effects when combined with beta-agonists like dobutamine or epinephrine due to different mechanisms of action 2