Can patients with aortic stenosis undergo Hyperbaric Oxygen Therapy (HBOT)?

Can Patients with Aortic Stenosis Undergo Hyperbaric Oxygen Therapy?

Patients with aortic stenosis, particularly those with severe disease or reduced left ventricular function, should generally avoid hyperbaric oxygen therapy (HBOT) due to significant risk of hemodynamic decompensation and pulmonary edema. 1

Evidence of Direct Harm

The strongest evidence comes from case reports documenting three patients who developed pulmonary edema during HBOT, including one fatality 1. Critically, one of these patients had severe aortic stenosis, and all had cardiac disease with reduced left ventricular ejection fractions 1. This represents the only direct evidence addressing this specific clinical question and demonstrates clear mortality risk.

Physiologic Mechanisms of Risk

HBOT poses multiple hemodynamic threats to patients with aortic stenosis:

• Increased left ventricular afterload from hyperbaric pressure, which is particularly dangerous in aortic stenosis where the left ventricle already faces fixed outflow obstruction 1
• Elevated left ventricular filling pressures that can precipitate acute decompensation in patients with limited cardiac reserve 1
• Increased oxidative myocardial stress and decreased left ventricular compliance through oxygen radical-mediated reduction in nitric oxide 1
• Bradycardia with concomitant left ventricular dysfunction, which reduces cardiac output in patients dependent on heart rate to maintain adequate perfusion 1
• Altered cardiac output distribution between right and left ventricles, potentially worsening hemodynamic balance 1

Risk Stratification by Severity

Severe Symptomatic Aortic Stenosis

Patients with symptomatic severe aortic stenosis face markedly increased perioperative morbidity and mortality with any intervention 2. These patients require aortic valve replacement before elective procedures 3, and HBOT should be considered contraindicated given the documented fatality 1.

Severe Asymptomatic Aortic Stenosis

Even asymptomatic patients with reduced ejection fraction (<50%) are at dramatically increased risk 4. The combination of severe aortic stenosis and reduced left ventricular function—the exact profile seen in the HBOT case series—creates prohibitive risk 1.

Moderate or Mild Aortic Stenosis

While no specific evidence addresses these populations, the physiologic mechanisms of harm (increased afterload, altered hemodynamics) remain relevant. Caution is warranted, particularly if ejection fraction is reduced 1.

Clinical Decision Algorithm

If HBOT is being considered:

1. Assess aortic stenosis severity with recent echocardiography (within 6-12 months for severe disease) 5
2. Evaluate left ventricular ejection fraction - any reduction below 50% substantially increases risk 1, 4
3. Determine symptom status - symptomatic patients should not proceed with HBOT until after aortic valve replacement 2, 3
4. Consider alternative treatments for the indication requiring HBOT, as the cardiac risk may outweigh potential benefits 1

Absolute contraindications to HBOT:

• Severe symptomatic aortic stenosis 2, 3, 1
• Severe aortic stenosis with reduced ejection fraction (<50%) 4, 1
• Heart failure or significantly reduced cardiac ejection fraction with any degree of aortic stenosis 1

Relative contraindications requiring cardiology consultation:

• Asymptomatic severe aortic stenosis with preserved ejection fraction 1
• Moderate aortic stenosis with any reduction in ejection fraction 1
• Diabetes mellitus combined with aortic stenosis (two of three patients in the case series had diabetes) 1

Critical Pitfalls to Avoid

• Do not assume asymptomatic status equals safety - reduced ejection fraction or elevated BNP indicates subclinical decompensation and high risk 6, 1
• Do not proceed without recent echocardiography - aortic stenosis severity and left ventricular function must be current 5
• Do not underestimate the afterload stress - the hyperbaric environment creates a fixed increase in left ventricular afterload that cannot be compensated in severe aortic stenosis 1
• Do not ignore concurrent cardiac conditions - diabetes, heart failure, and reduced ejection fraction compound the risk 1

Monitoring If HBOT Must Proceed

If HBOT is deemed absolutely necessary in a patient with mild-to-moderate aortic stenosis and preserved left ventricular function:

• Obtain cardiology clearance with comprehensive risk assessment 5
• Ensure continuous hemodynamic monitoring during treatment 1
• Have immediate access to advanced cardiac life support and mechanical circulatory support 1
• Monitor closely for signs of pulmonary edema, including oxygen desaturation, dyspnea, and hemodynamic instability 1
• Consider prophylactic diuresis before treatment in patients with any degree of volume overload 1