Ever danced so hard you thought you were going to pass out from exhaustion? Run so far or exercised so much that your heart was pounding in your chest as you dripped with sweat? Maybe you spent all day in the hot, summer sun and never drank any water?
What do these have in common? They can all cause sudden cardiac arrest (SCA) due to dehydration and loss of important electrolytes. SCA occurs when the heart begins contracting irregularly due to erratic electrical impulses and blood is not able to pump at its normal rate and rhythm. Once your heart stops pumping blood, you die.
Dehydration is an important factor in SCA for two reasons. First, all that sweating without replacing your liquid loss means less fluid pumping through your arteries. This causes your body to constrict your blood vessels and your heart to pump harder in an effort to maintain appropriate cardiac output and blood pressure. Decreased blood supply to the brain can cause mental confusion, fogginess, lethargy, fatigue and may ultimately result in a coma.
Second, sweat causes an imbalance in your sodium and potassium levels which can lead to heart arrhythmias or abnormal beats. If you put the two together, you have decreased blood supply, constricted vessels, and abnormal beats leading to cardiac arrest.
Thankfully, dehydration doesn’t happen instantly. Your body is very dynamic and will continually adjust itself to your situation until it just can’t give anymore. When you are losing a lot of sweat, it may take a few hours for your cardio-system to rebalance itself and shift around electrolytes throughout your body. If you continue to sweat and use up your water without replacing it, the rebalancing begins to falter and things start to fail.
Cardiac arrest has been in the news over the last few years especially in young athletes practicing in the heat of summer without adequate water and electrolyte replacement. Additionally, some sites are reporting it may have contributed to the death of Michael Jackson. He was reported to have been practicing like crazy for the upcoming tour without replenishing much food or water.