How to increase cardiac index in post-operative aortic valve replacement (AVR) patients?

From the Guidelines

To increase cardiac index in post-operative aortic valve replacement patients, optimize preload with careful fluid administration targeting a central venous pressure of 8-12 mmHg or using dynamic parameters like stroke volume variation. Inotropic support is often necessary, with dobutamine (starting at 2-5 mcg/kg/min, titrating up to 20 mcg/kg/min) being first-line for its beta-1 adrenergic effects that increase contractility with minimal vasoconstriction 1. Milrinone (0.375-0.75 mcg/kg/min) is an alternative that combines inotropic effects with vasodilation, particularly useful in patients with pulmonary hypertension. Epinephrine (0.01-0.1 mcg/kg/min) can be added for more severe low cardiac output states. Ensure adequate heart rate control, targeting 80-100 beats per minute in most cases, as both bradycardia and tachycardia can reduce cardiac output. Maintain adequate mean arterial pressure (65-75 mmHg) using vasopressors like norepinephrine if needed. Minimize afterload with vasodilators such as nitroglycerin or nitroprusside when blood pressure allows, as seen in studies evaluating the management of patients with valvular heart disease 1. Optimize oxygen delivery with appropriate hemoglobin levels (>8 g/dL), adequate oxygenation, and normothermia. Atrial pacing or temporary atrioventricular pacing may help optimize cardiac output in patients with conduction abnormalities. These interventions work by improving the determinants of cardiac output: preload, afterload, contractility, and heart rate, while ensuring adequate oxygen delivery to tissues. Key considerations include:

• Monitoring and adjusting fluid status to maintain optimal preload
• Using inotropic agents judiciously to support cardiac function
• Maintaining adequate heart rate and mean arterial pressure
• Minimizing afterload when possible
• Optimizing oxygen delivery to tissues
• Considering pacing interventions for conduction abnormalities These strategies are supported by guidelines for the management of patients with valvular heart disease, including those undergoing aortic valve replacement 1.

From the FDA Drug Label

Dobutamine is a direct-acting inotropic agent whose primary activity results from stimulation of the β receptors of the heart while producing comparatively mild chronotropic, hypertensive, arrhythmogenic, and vasodilative effects. In patients with depressed cardiac function, both dobutamine and isoproterenol increase the cardiac output to a similar degree The cardiac stroke volume is usually increased. Systemic vascular resistance is usually decreased with administration of dobutamine.

To increase cardiac index in post-operative aortic valve replacement (AVR) patients, dobutamine can be used as it is a direct-acting inotropic agent that increases cardiac output and stroke volume. The effective infusion rate of dobutamine varies widely from patient to patient, and titration is always necessary 2.

From the Research

Increasing Cardiac Index in Post-Operative Aortic Valve Replacement (AVR) Patients

To increase cardiac index in post-operative AVR patients, several strategies can be employed:

• The use of inotropes such as milrinone and levosimendan has been shown to increase cardiac index by approximately 20% in patients after AVR for aortic stenosis 3.
• Nitroprusside, a vasodilator, has been used to improve myocardial performance in patients with severe aortic stenosis and left ventricular systolic dysfunction, resulting in a significant increase in cardiac index 4.
• Inotropes such as epinephrine and milrinone have been found to improve right heart function in patients undergoing AVR for aortic stenosis, leading to increased cardiac output and index 5.
• Maintaining optimal blood pressure is crucial, as lower systolic blood pressure after TAVR has been associated with higher mortality, while higher total and pulsatile arterial load have been linked to increased mortality 6.

Inotrope Therapy

Inotrope therapy can be beneficial in increasing cardiac index in post-operative AVR patients:

• Milrinone and levosimendan have been shown to have comparable direct RV inotropic and lusitropic effects at clinically relevant infusion rates 3.
• Epinephrine and milrinone have been found to improve biventricular performance after aortic valve replacement, with a greater impact on right ventricular function 5.

Hemodynamic Management

Hemodynamic management is critical in post-operative AVR patients:

• Maintaining optimal blood pressure and arterial load is essential to ensure adequate cardiac perfusion and function 6.
• The use of vasodilators such as nitroprusside can help improve myocardial performance and increase cardiac index in patients with severe aortic stenosis and left ventricular systolic dysfunction 4.