Pacemakers are small, battery-operated devices that help the heart beat in a regular rhythm. They do this by generating a mild electrical current that stimulates the heart to beat.
The device is implanted under the skin of the chest just below the collarbone. It connects to the heart with tiny wires that thread into the heart through the major blood vessels. In some individuals, the heart may need only intermittent help from the pacemaker if the pause between two beats becomes too long. In others, however, the heart may depend entirely on the pacemaker for regular stimulation.
Implications in Diving
The need for a pacemaker usually indicates a disturbance in the heart’s conduction system. The disturbance might be from structural damage to the heart muscle, as is often the case following a major heart attack. In this case one might lack the necessary cardiovascular fitness to dive safely.
You might depend on a pacemaker because the area that generates the impulses that make the heart muscle contract does not function consistently or adequately. The circuitry that conducts the impulses to the heart muscle may be faulty, resulting in improper or irregular signals. Without the assistance of a pacemaker, one might suffer episodes of loss of consciousness or fainting.
Due to the risk of drowning, any medical condition that could predispose a diver to suffer a sudden loss of consciousness is a contraindication for diving.
A mild heart attack could cause minimal residual damage to your heart muscle. Even with minimal damage, the conduction system could be unreliable and dependent upon a boost from a pacemaker. A cardiologist can determine if your level of cardiovascular fitness is sufficient for safe diving. Your pacemaker needs to be rated to function at a pressure of at least 130 feet (40 meters) to be considered fit for recreational diving.
Any divers with heart issues should have an evaluation for medical fitness before diving. A significant number of recreational diving fatalities each year are attributable to coronary artery disease.
For the Diver
- Diving often occurs in remote locations far from facilities that provide an adequate level of cardiac care for someone with a pacemaker.
- Be mindful of your cardiovascular condition and the remoteness of your dive locations.
For the Dive Operator
- Consider each individual’s health status on a case-by-case basis. Divers or dive students with significant cardiovascular disease and less-than-optimal exercise tolerance should be discouraged from participating in scuba diving. The individual must have adequate exercise tolerance for safe diving under routine conditions. They must also possess enough cardiovascular reserve to perform at the higher level needed in emergencies.
- Assessing someone’s cardiovascular fitness to dive is beyond the scope of a dive instructor. When in doubt, encourage your client to present a medical clearance to scuba dive signed by their physician and keep a copy for your records.
- If you are in doubt or feel uncomfortable about your client’s safety, remember you always have the right of refusal.
- Resource: Right of Refusal – Alert Diver © Q4 Fall 2019.
For the Physician
Relevant literature about implantable devices under increased barometric pressure:
- Exposing Boston Scientific implantable devices to elevated pressure – Boston Scientific 2009
- Hyperbaric Oxygen in Patients with implanted Cardiac Defibrillators and Pacemakers – UHMS 2006
- Activity-based rate-adaptive pacemakers under hyperbaric conditions – Journal of Interventional Cardiolgy and Electrophysiology (2006)
- Cardiac Pacing under Hyperbaric Conditions – The Annals of Thoracic Surgery (1983)
Fitness to dive
A pacemaker experiences the same ambient pressures as the diver. For recreational diving, a suitable pacemaker must perform at a maximum depth of at least 130 feet (40 meters). It must operate satisfactorily during conditions of relatively rapid pressure changes on ascent and descent.
A pacemaker and cardiac defibrillator are not the same — both may be needed by some patients. The need for a cardiac defibrillator is a contraindication for diving. It is implanted for those at high risk for cardiac arrest and shock if indicated. A period of altered consciousness and subsequent drowning is likely during this period of defibrillator intervention while underwater.
As with any medication or medical device, the underlying problem that led to the implantation of the pacemaker is the most significant factor in determining someone’s fitness to dive. Every case involving a pacemaker is specific to the individual.
The two most important factors to consider are the following:
- Why is the individual dependent on a pacemaker? The most common reason people depend on pacemakers is underlying ischemic heart disease. Although the pacemaker might address the cardiac dysrhythmia, the underlying heart disease might still be significant enough to disqualify someone from diving.
- Is the individual’s pacemaker rated to perform as intended at depths under the pressures involved in recreational diving plus an added margin of safety? Although there are no air pockets in these devices, and there are no reports of case deformation due to pressure, this concern is still valid. BCD straps over the device might cause discomfort.