What is the preferred choice between norepinephrine (Levophed) and epinephrine for post-operative blood pressure management in a patient who has undergone aortic valve replacement (AVR)?

Norepinephrine vs Epinephrine Post-AVR

Norepinephrine (levophed) is the preferred vasopressor for blood pressure management after aortic valve replacement, particularly when hypotension requires treatment without significant need for inotropic support. 1, 2

Rationale for Norepinephrine Preference

The primary goal post-AVR is maintaining adequate coronary perfusion pressure while avoiding excessive tachycardia. 1, 3 Norepinephrine achieves this through:

• Pure alpha-adrenergic vasoconstriction with minimal chronotropic effects, maintaining coronary perfusion without increasing myocardial oxygen demand 1, 2
• Prevention of anesthesia-induced hypotension when started prophylactically at 0.1 μg/kg/min during induction in severe AS patients undergoing TAVR 2
• Maintenance of diastolic blood pressure, which is critical for coronary perfusion in the post-AVR setting where coronary flow can drop below physiologic minimums when DBP falls below 60 mmHg 3

When Epinephrine May Be Indicated

Epinephrine should be reserved for situations requiring combined inotropic and vasopressor support, particularly when right ventricular dysfunction is present. 4

• Both epinephrine and milrinone improved biventricular function equally after AVR, with greater impact on right ventricular ejection fraction (+9% with epinephrine vs +0.5% with placebo) 4
• Changes in cardiac output correlated more strongly with RV function (r=0.56) than LV function (r=0.22) after AVR 4
• No patients developed left ventricular outflow tract obstruction with epinephrine use in the post-AVR setting 4

Critical Hemodynamic Targets Post-AVR

Maintain systolic blood pressure >120 mmHg and diastolic pressure >60 mmHg to ensure adequate coronary perfusion. 3

• Coronary flow decreases below physiologic minimums when SBP <120 mmHg and DBP <60 mmHg in controlled studies with various valve prostheses 3
• Phenylephrine or norepinephrine can be used to increase blood pressure in patients without significant CAD during the perioperative period 1
• Avoid hypotension and tachycardia, as decreased coronary perfusion pressure can result in arrhythmias, myocardial injury, cardiac failure, or death 1

Specific Clinical Algorithm

For isolated hypotension without low cardiac output:

• Start norepinephrine 0.05-0.1 μg/kg/min 1, 2
• Titrate to maintain MAP >65 mmHg and DBP >60 mmHg 3

For hypotension with low cardiac output or RV dysfunction:

• Consider epinephrine 0.01-0.05 μg/kg/min OR milrinone 0.375-0.75 μg/kg/min 4
• Both provide equivalent biventricular support 4
• Choice depends on blood pressure (epinephrine if hypotensive, milrinone if normotensive) 4

For wide pulse pressure post-AVR:

• Use ACE inhibitors or ARBs, NOT beta blockers 5
• Beta blockers paradoxically worsen pulse pressure by reducing heart rate and increasing stroke volume 5
• Vasodilating drugs reduce systolic pressure without substantially affecting diastolic pressure 5

Common Pitfalls to Avoid

• Do not use beta blockers for blood pressure control in the immediate post-AVR period, as they worsen hemodynamics by reducing heart rate and increasing stroke volume 5
• Do not allow diastolic pressure to fall below 60 mmHg, as this critically impairs coronary perfusion 3
• Do not assume preserved LV systolic function means inotropes are unnecessary—RV function is often the limiting factor for cardiac output post-AVR 4
• Avoid aggressive diuretic therapy early post-procedure to prevent acute kidney injury 5

Monitoring Requirements

• Continuous invasive blood pressure monitoring with right-heart catheter or intraoperative TEE for optimization of loading conditions 1
• Monitor for 24-48 hours postoperatively until hemodynamics are stable 1
• Maintain sinus rhythm and normal heart rate—tachycardia decreases coronary perfusion time 1