Cardiovascular health plays a formidable part in the safety of any dive. Issues like high blood pressure, coronary heart disease, congenital heart disease, smoking and a family history of heart disease can all compromise cardiovascular health.
Both high blood pressure and heart disease have consistently been the most frequently reported chronic health conditions contributing to dive fatalities for many years. In the 2004 DAN Report on Decompression Illness, Diving Fatalities and Project Dive Exploration, more than 14 percent of the fatalities reported had a chronic history of high blood pressure and/or heart disease. Obesity, another factor reported in 55 percent of fatalities, is connected to heart disease and hypertension, with results linking to poor health and poor exercise tolerance. In combination with other contributing factors, poor cardiovascular health can increase the risk of a severe or fatal dive incident.
To decrease their odds of developing a serious health conditions and to keep the cardiovascular system in tip-top shape, divers can abstain from smoking, exercise regularly and eat a balanced diet. When a diver understands their risks, they are better able to make choices that can positively affect their diving and overall health.
Despite preventative measures, however, sometimes medications are needed to treat these conditions. While cardiovascular medications can help a person with a condition, they do influence someone’s ability to dive safety. Below are some common medications that are used to treat conditions like hypertension and high blood pressure, and possible implications in diving.
Commonly used to treat hypertension, beta blockers have a big drawback: They can reduce the heart’s capacity for exercise and therefore affect your exercise tolerance. In addition, if medication restricts the heart’s function during exercise, then there is an increased risk of loss of consciousness, which could prove fatal underwater.
Because of this effect on divers, doctors often recommend a stress test. Divers who use beta blockers and who can achieve a strenuous level of exercise without severe fatigue may be cleared for diving. Although diving does not usually represent the maximum workload on the heart, divers taking beta blockers should avoid extreme exercise because their maximum capacity for exercise may be reduced.
ACE (Angiotension-converting enzyme) inhibitors have less effect on exercise than beta blockers, so doctors prescribe them for people who exercise more often. Although ACE inhibitors seem to have fewer adverse effects on divers, they can produce a cough and airway swelling — both conditions can cause severe problems underwater. Most people can usually tolerate a mild cough on land, but if a cough due to the drug persists, many physicians will change medications. In the presence of kidney disease, ACE inhibitors should be avoided.
Calcium Channel Blockers
Calcium channel blockers don’t typically pose problems for divers: they relax the walls of blood vessels, reducing blood flow resistance and thus lowering blood pressure. In some cases, especially in moderate doses, a change in position from sitting or lying down to standing may cause excessively low blood pressure and a subsequent momentary dizziness. This postural blood pressure change may be a cause for concern with divers, but calcium blockers appear to have no other adverse reaction for diving.
Diuretics reduce the amount of excess water and salt in the body, thus lowering the blood pressure. Divers seem to have very little trouble with diuretics, although in very warm environments, they may cause excessive water loss and dehydration. Because dehydration seems to be a contributing factor to the risk of decompression sickness, divers may want to reduce the dosage on the day of diving. Before changing dosages, however, check with your doctor.
Antiarrhythmics are designed to help maintain a stable heart rhythm. Some antiarrhythmics, when combined with exercise and a loss of potassium, could increase the risk of injuring the heart. Although these medicines normally do not interfere with diving, the dysrhythmia, or abnormal heart rate for which the medication is being taken, may be a contraindication to diving. Through consultation, a cardiologist and a dive medicine physician should evaluate anyone who has an abnormal heart rate and requires medication.
A diver who has been prescribed an anticoagulant (e.g., Coumadin® or Warfarin®) should be warned of the potential for bleeding: excessive bleeding can occur from even a seemingly benign ear or sinus barotrauma. There is a potential risk that, if decompression illness (DCI) occurs, it may then cause significant bleeding in the brain or spinal cord
Overall Implications in Diving
Cardiovascular disease can contribute to dive injuries as well as fatalities — both are preventable. With increased information about cardiovascular health and fitness, divers can make better choices and increase the opportunity that every dive will be accident- and injury-free. Read all you can about your medications and consult with your doctor.