What are the primary hemodynamic goals in the post-operative period for patients with severe Aortic Stenosis (AS) and Heart Failure with reduced Ejection Fraction (HFrEF) after Aortic Valve Replacement (AVR)?

Hemodynamic Goals Post-AVR in Severe AS with HFrEF

In patients with severe aortic stenosis and HFrEF undergoing AVR, the primary hemodynamic goals are to maintain adequate preload (avoid hypovolemia), optimize cardiac output through heart rate control (avoid bradycardia which worsens regurgitation and tachycardia which reduces filling time), prevent hypotension while avoiding excessive afterload, and aggressively manage pulmonary pressures given the high prevalence of pulmonary hypertension in this population. 1, 2, 3

Preload Management

• Maintain adequate filling pressures while avoiding volume overload, as these patients often have elevated pulmonary capillary wedge pressure (PCWP) pre-operatively that improves post-AVR 3, 4
• Fluid boluses effectively increase stroke volume index (from 37 to 48 ml/min/m²) but at the cost of increased PCWP, particularly in patients with larger left atrial volumes 4
• Target PCWP reduction from pre-operative levels of approximately 22 mm Hg to post-operative goals of 9 mm Hg, as demonstrated in successful AVR outcomes 2

Cardiac Output Optimization

• Prioritize stroke volume over heart rate for cardiac output augmentation, as dobutamine primarily increases heart rate rather than stroke volume in AS patients under anesthesia 4
• Expect significant improvement in left ventricular ejection fraction post-operatively (from 0.34-0.37 to 0.63) in patients with pre-operative HFrEF, indicating afterload mismatch as the primary mechanism 2, 3
• Classic low-flow, low-gradient AS (CLFLG-AS) represents the true HFrEF form and shows significant elevation in stroke volume index and left ventricular stroke work index post-TAVR 3

Afterload Management

• Avoid hypotension aggressively as AS patients are at increased risk of hypoperfusion during surgery 4
• Target reduction in global afterload post-procedure, particularly in low-flow AS variants where significant afterload reduction occurs after valve replacement 3
• General anesthesia causes decreased cardiac index and stroke volume index compared to pre-operative values, requiring vigilant monitoring 4

Heart Rate Control

• Avoid bradycardia as it worsens any residual regurgitation by prolonging diastolic filling time 5
• Avoid excessive tachycardia which reduces diastolic filling time and coronary perfusion
• Dobutamine's effect on stroke volume is highly variable and associated with baseline LVEF, with increases in cardiac index primarily driven by heart rate elevation rather than stroke volume 4

Pulmonary Pressure Management

• Aggressively monitor and manage pulmonary hypertension, as 40% of severe AS patients have pre-AVR pulmonary hypertension (mean PAP ≥25 mmHg) 6
• Patients with post-AVR pulmonary hypertension (12% prevalence) had significantly higher pre-operative mean PAP, mean PAWP, pulmonary vascular resistance, and lower pulmonary artery capacitance 6
• Both paradoxical low-flow and classic low-flow AS show early hemodynamic reverse response with reduction in global afterload after valve replacement 3

Ventricular Function Monitoring

• Expect dramatic improvement in mean velocity of circumferential fiber shortening (from 0.57 to 1.3 circ/sec) post-operatively 2
• Monitor for reduction in left ventricular end-diastolic volume index (from 119 to 107 ml/m²) and end-diastolic pressure (from 22 to 9 mm Hg) 2
• Left ventricular ejection fraction typically increases by 10 units and may return to normal if afterload mismatch was the primary cause of dysfunction 1

Special Considerations for HFrEF Population

• Even patients with severely depressed LVEF (<35%) benefit from AVR with improved survival compared to medical therapy alone 1
• Survival at 1,5, and 10 years post-AVR in severe LV dysfunction patients (LVEF <30%) is 92%, 79%, and 51% respectively in modern surgical series 1
• The depressed LVEF in many patients is caused by excessive afterload (afterload mismatch), and LV function improves after AVR 1

Inotropic Support Strategy

• Use dobutamine cautiously, recognizing that higher pre-operative EF and stroke volume index, along with larger decreases in stroke volume after anesthesia induction, predict better response to dobutamine 4
• Fluid administration is more predictable than inotropes for increasing stroke volume, though it increases filling pressures 4

Common Pitfalls to Avoid

• Do not withhold AVR based solely on low LVEF, as outcomes are still superior to medical management even with LVEF <30% 1, 2
• Avoid assuming all low-gradient AS has the same hemodynamic profile—classic low-flow has the worst prognosis while normal-flow low-gradient has adequate LV compensation 3
• Do not overlook pulmonary hypertension assessment, as 88% of patients with post-AVR PH already had pre-AVR PH 6