What are the cardiac contraindications for hyperbaric oxygen therapy?

Cardiac Contraindications for Hyperbaric Oxygen Therapy

Severe hemodynamic instability and cardiac instability are absolute contraindications for hyperbaric oxygen therapy due to significant risks that outweigh potential benefits. 1

Primary Cardiac Contraindications

Absolute Contraindications

• Severe hemodynamic instability requiring vasopressor support 1
• Cardiac instability including:
  • Acute decompensated heart failure (NYHA class IV) 2, 1
  • Recent cardiac arrest 2
  • Unstable angina or acute coronary syndrome requiring urgent intervention 3
  • Severe arrhythmias 1

Relative Contraindications

• Heart failure with reduced ejection fraction (HFrEF) 4

  • Particularly with LVEF <35%
  • Concomitant right ventricular dysfunction
  • Pulmonary hypertension
  • Moderate to severe tricuspid regurgitation

• Heart failure with preserved ejection fraction (HFpEF) 4

  • May still develop pulmonary edema during HBOT despite normal LVEF

• NYHA Class III heart failure 2

  • Requires careful evaluation and optimization before considering HBOT
  • May need supplemental oxygen during treatment

Physiological Basis for Contraindications

HBOT causes several hemodynamic changes that can be problematic for cardiac patients:

1. Increased afterload due to peripheral vasoconstriction 4
2. Decreased cardiac output during treatment 4
3. Increased oxygen demand on the myocardium 3
4. Pulmonary vasoconstriction potentially worsening pulmonary hypertension 2

Risk Assessment and Management

Pre-HBOT Cardiac Evaluation

• Comprehensive cardiac history focusing on:

  • Recent cardiac events or interventions
  • Current NYHA functional class
  • Medication adherence, especially diuretics 4
  • Exercise tolerance at sea level 2

• Consider targeted cardiac investigations for high-risk patients 5

  • Not all patients require routine ECG or echocardiogram before HBOT
  • Focus on clinical parameters to identify those at highest risk

Risk Mitigation Strategies

• Optimize heart failure therapy before initiating HBOT 4

  • Ensure appropriate diuretic dosing
  • Maintain fluid restriction
  • Continue all cardiac medications

• Monitoring during HBOT

  • Continuous vital sign monitoring
  • Observation for signs of respiratory distress
  • Prompt recognition of pulmonary edema

Special Considerations

Recently Placed Vascular Closure Devices

• May be a contraindication if placed within 7 days 1
• Risk of device failure, pseudoaneurysm formation, or hematoma

Post-Cardiac Intervention Timing

• After heart transplantation: avoid HBOT for at least 1 year 2
• After implantable cardioverter-defibrillator or cardiac resynchronization therapy: avoid HBOT for at least 2 weeks 2

Common Pitfalls and Caveats

1. Failure to recognize fluid status changes

   • Patients may hold diuretics before HBOT, increasing risk of pulmonary edema 4
   • Regular weight monitoring and assessment of fluid status is essential

2. Overlooking medication adherence

   • Non-adherence to diuretics is a major risk factor for HBOT complications in cardiac patients 4

3. Assuming all heart failure patients have the same risk

   • HFpEF patients can also develop complications during HBOT 4
   • Risk assessment should be individualized based on cardiac function and stability

4. Underestimating transport risks

   • The risks of transporting critically ill cardiac patients to hyperbaric facilities may outweigh potential benefits 2

While some studies suggest potential benefits of HBOT in certain cardiac conditions like chronic ischemic heart disease 6 or as an adjunct in acute myocardial infarction 7, these remain investigational. The primary consideration should be patient safety, with careful assessment of cardiac status before proceeding with HBOT.