What inotropes and vasodilators are recommended during weaning from cardiopulmonary bypass (CPB) in a patient with mitral valve regurgitation (MR) after mitral valve replacement (MVR) and concomitant aortic regurgitation (AR)?

From the Guidelines

For weaning from cardiopulmonary bypass (CPB) in a patient with mitral valve regurgitation after mitral valve replacement (MVR) who also has aortic regurgitation, I recommend using low-to-moderate doses of dobutamine and milrinone as the primary inotropes, considering their ability to improve stroke volume and decrease pulmonary capillary wedge pressure (PCWP) while minimizing tachycardia 1. When selecting inotropes, it's crucial to consider the patient's specific hemodynamic needs, including the presence of both mitral and aortic regurgitation.

• Dobutamine, starting at 2-5 mcg/kg/min, can be titrated up to 10 mcg/kg/min as needed, providing inotropic support and increasing heart rate while moderately decreasing PCWP 1.
• Milrinone, with its dual effect of inotropic support and pulmonary vasodilation, is an excellent alternative or addition, starting with a loading dose of 50 mcg/kg over 10 minutes followed by an infusion of 0.375-0.75 mcg/kg/min 1. For vasodilation, nitroglycerin at 0.5-5 mcg/kg/min can be beneficial to reduce afterload and improve forward flow, which is particularly important in the context of aortic regurgitation to decrease regurgitant volume 1. In cases where significant hypotension is a concern, norepinephrine at 0.01-0.1 mcg/kg/min can be added to maintain adequate perfusion pressure, ensuring that volaemia is repeatedly assessed to avoid hypovolemia while under vasopressors 1. The choice and dosage of these medications should be guided by continuous hemodynamic monitoring, including arterial pressure, central venous pressure, pulmonary artery pressure, and cardiac output measurements, aiming to optimize cardiac output while minimizing regurgitant flow across both valves by balancing preload, afterload, and contractility 1.

From the FDA Drug Label

Milrinone lactate is a positive inotrope and vasodilator, with little chronotropic activity different in structure and mode of action from either the digitalis glycosides or catecholamines Milrinone lactate, at relevant inotropic and vasorelaxant concentrations, is a selective inhibitor of peak III cAMP phosphodiesterase isozyme in cardiac and vascular muscle Clinical studies in patients with congestive heart failure have shown that milrinone lactate produces dose-related and plasma drug concentration-related increases in the maximum rate of increase of left ventricular pressure Milrinone lactate also produces dose-related and plasma concentration-related increases in forearm blood flow in patients with congestive heart failure, indicating a direct arterial vasodilator activity of the drug.

The inotrope that can be used during weaning from CPB in case of mitral valve regurgitation after MVR, in a patient who also has aortic regurgitation, is milrinone.

• Key benefits: increases myocardial contractility and improves diastolic function
• Mechanism of action: selective inhibitor of peak III cAMP phosphodiesterase isozyme in cardiac and vascular muscle 2

From the Research

Inotropes and Vasodilators for Weaning from CPB

In the context of mitral valve regurgitation after mitral valve replacement (MVR) and concomitant aortic regurgitation, the management of weaning from cardiopulmonary bypass (CPB) is crucial. The choice of inotropes and vasodilators can significantly impact the patient's hemodynamic stability and outcome.

Available Evidence

• A study published in 2018 3 compared mitral valve repair and replacement in patients with ischemic mitral regurgitation, but did not specifically address the use of inotropes and vasodilators during weaning from CPB.
• Another study from 2018 4 reported the use of an Alfieri stitch to manage temporary severe functional mitral regurgitation after aortic valve replacement, highlighting the importance of addressing mitral regurgitation during weaning from CPB.
• A study published in 2014 5 compared outcomes between double valve replacement and aortic valve replacement plus mitral valve repair, but did not provide specific guidance on inotropes and vasodilators.
• A 2018 study 6 evaluated the long-term results of concomitant mitral and aortic valve surgery, emphasizing the importance of mitral valve repair whenever feasible.
• A 2009 study 7 investigated the management of moderate functional mitral regurgitation at the time of aortic valve replacement, suggesting that concomitant mitral valve repair may not always be necessary.

Key Considerations

• The choice of inotropes and vasodilators during weaning from CPB should be tailored to the individual patient's hemodynamic profile and underlying cardiac pathology.
• Mitral valve regurgitation and aortic regurgitation can significantly impact the patient's hemodynamic stability, and the use of inotropes and vasodilators should be guided by careful monitoring of cardiac function and hemodynamics.
• The available evidence does not provide specific recommendations for the use of inotropes and vasodilators in this context, highlighting the need for further research and individualized patient management.