Is it safe for individuals with subcutaneous implantable cardioverter-defibrillators (ICDs) to use hot tubs?

Hot Tub Use with Subcutaneous ICDs: Safety Considerations

Patients with subcutaneous ICDs should exercise caution when using hot tubs due to documented risk of inappropriate shocks from electrical interference, though this risk appears manageable with proper precautions.

Primary Safety Concern: Electrical Interference

The main risk with hot tub use involves electromagnetic interference from the hot tub's electrical system, which can be misinterpreted by the ICD as ventricular fibrillation:

• Hot tub engines can generate 60-cycle electrical artifacts that mimic fast ventricular fibrillation, triggering inappropriate ICD shocks 1
• A documented case involved a 72-year-old patient who received a 34.8 joule shock while actually in normal sinus rhythm, caused by hot tub jet-induced electrical interference 1
• Similar inappropriate shocks have been reported with swimming pools due to alternating-current leaks 2

Device-Specific Considerations for Subcutaneous ICDs

Subcutaneous ICDs have particular sensing characteristics that affect their vulnerability to external interference:

• The subcutaneous system uses surface electrodes positioned between the fifth and sixth intercostal spaces, making them potentially more susceptible to external electrical noise than transvenous systems 3
• Subcutaneous ICDs rely on SVT-VT discriminators that do not always work perfectly, and external electrical interference can overwhelm these algorithms 3
• All ICD shocks in awake patients are painful and associated with decreased quality of life, making prevention of inappropriate shocks particularly important 3

Risk Mitigation Strategies

Pre-Activity Assessment

• Ensure the hot tub's electrical system is properly grounded and maintained to minimize stray electrical currents 1, 2
• Consider having the hot tub inspected by a qualified electrician to verify no current leaks are present 2

Patient Education Points

• Patients should be counseled about potential electromagnetic interference sources as part of routine ICD follow-up 3
• Exit the hot tub immediately if any unusual sensations, palpitations, or device alerts occur 1
• Avoid positioning the device side of the body directly adjacent to water jets or pump outlets where electrical interference may be strongest 1

Device Programming Considerations

• Dual-zone programming has been shown to decrease inappropriate shock rates with subcutaneous ICDs 4
• Consider programming adjustments to reduce sensitivity to noise if the patient plans regular hot tub use 5
• Device interrogation should be performed if any concerning symptoms occur during or after hot tub use 3

Common Pitfalls to Avoid

• Do not assume all hot tubs are equally safe - older or poorly maintained systems pose higher risk 1, 2
• Avoid dismissing patient concerns about device behavior in water environments - inappropriate shocks from external interference are well-documented 1, 2
• Do not overlook the psychological impact of inappropriate shocks, which can cause significant anxiety and decreased quality of life 3, 6

Practical Recommendation Algorithm

For patients with subcutaneous ICDs considering hot tub use:

1. Verify hot tub electrical safety through professional inspection 1, 2
2. Start with brief exposures (5-10 minutes) while monitoring for any device alerts or unusual sensations 1
3. Position away from jets and pumps to minimize exposure to electrical components 1
4. Schedule device interrogation if any concerning symptoms occur 3
5. Consider alternative relaxation methods if inappropriate shocks occur despite precautions 1

The risk is real but manageable - hot tub use is not absolutely contraindicated, but requires informed decision-making and appropriate precautions to minimize the risk of painful inappropriate shocks 1, 2.