Is controlled hypertension compatible with scuba diving?

Controlled Hypertension and Scuba Diving

Recreational scuba diving is generally compatible with controlled hypertension, provided the blood pressure is well-managed and there is no evidence of end-organ damage or cardiovascular complications. 1

Risk Assessment for Divers with Hypertension

Blood Pressure Classification and Diving Eligibility

• Well-controlled hypertension (Stage 1 or controlled Stage 2): Generally compatible with recreational diving 1
• Uncontrolled hypertension (BP >180/120 mmHg or with end-organ damage): Should not dive until adequate control is achieved 1

Cardiovascular Evaluation

• For divers with Stage 2 hypertension, obtain:
  • 12-lead ECG
  • Echocardiogram to assess for cardiac remodeling 1
  • Cardiac ischemic risk assessment for those with established atherosclerotic cardiovascular disease 1

Physiological Considerations

Scuba diving creates unique cardiovascular challenges that can affect hypertensive individuals:

1. Hydrostatic pressure effects: Increased pressure at depth can affect blood pressure regulation 1
2. Cold-induced diving reflex: Causes complex autonomic activation that may trigger arrhythmias ("autonomic conflict") 1
3. Immersion effects: Central blood pooling increases cardiac preload, raising cardiac output and blood pressure 2

Special Considerations for Medication

When prescribing antihypertensive medications for divers:

• Consider medications that won't impair exercise capacity or alertness underwater
• Avoid medications that might increase risk of syncope or sudden incapacitation
• Be aware that some medications may be prohibited in competitive diving 1

Risk Stratification

The risk of harm during diving can be calculated using the formula:

• Risk of harm = Time diving × Sudden cardiac incapacitation rate 3
• A cardiovascular event risk exceeding 2% per year may render a diver "unfit to dive" 3

Important Cautions and Contraindications

• Hypertensive emergency: Individuals with BP >180/120 mmHg with evidence of end-organ damage should not dive until blood pressure is controlled 1
• Left ventricular hypertrophy: Beyond expected "athlete's heart" changes requires blood pressure normalization before diving 4
• Cardiovascular events underwater: Have higher risk of adverse outcomes not only for the diver but also for other dive team members 1

Shared Decision-Making Approach

When counseling patients with controlled hypertension who wish to dive:

1. Discuss the additional risks of cardiovascular events occurring underwater
2. Emphasize the importance of maintaining medication adherence
3. Recommend regular blood pressure monitoring (every 2-4 months) 4
4. Consider the impact on other dive team members if a cardiovascular event occurs 1

Recreational diving with established cardiovascular disease, including well-controlled hypertension, can be considered with appropriate shared decision-making that acknowledges the unique risks of the underwater environment 1.