Olympian Dana Vollmer Gets to the Heart of the Matter

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US Olympic swimmer Dana Vollmer won a Gold Medal in 100 meter butterfly in world record time.

This is quite an accomplishment. But it is even more so for Vollmer who, just nine years ago, wasn’t sure whether a heart condition would force her to stop swimming altogether.

In 2003, Vollmer underwent heart surgery to correct a rhythym disturbance in her heart called SVT (supraventricular tachycardia).

After that surgery, an EKG indicated that she might have Long QT Syndrome; however, further testing indicated that she did not have the syndrome. Nonetheless, her heart conditions demand that a defibrillator be kept poolside when she swims as a precautionary measure.

What is an arrhythmia?

An arrhythmia is a problem with the rate or rhythm of the heartbeat. During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm.

A heartbeat that is too fast is called tachycardia. A heartbeat that is too slow is called bradycardia.

Most arrhythmias are harmless, but some can be serious or even life threatening. When the heart rate is too fast, too slow, or irregular, the heart may not be able to pump enough blood to the body. Lack of blood flow can damage the brain, heart, and other organs.

To understand arrhythmias, it is important to understand the electrical activity of the heart. The heart’s electrical system controls all the events that occur when the heart pumps blood. The electrical system also is called the cardiac conduction system. If you’ve ever seen the heart test called an EKG (electrocardiogram), you’ve seen a graphical picture of the heart’s electrical activity.

The heart’s electrical system is made up of three main parts:

  • The sinoatrial (SA) node, located in the right atrium of your heart
  • The atrioventricular (AV) node, located on the interatrial septum close to the tricuspid valve
  • The His-Purkinje system, located along the walls of your heart’s ventricles

This is a short video about how these main components of the electrical system come together:

It’s Not the Fastest Heart Beat that Wins the Race

Supraventricular arrhythmias are tachycardias (fast heart rates) that start in the atria or the atrioventricular (AV) node. Types of supraventricular arrhythmias include atrial fibrillation (AF), atrial flutter, paroxysmal supraventricular tachycardia (PSVT), and Wolff-Parkinson-White (WPW) syndrome.

AF is the most common type of serious arrhythmia. It’s a very fast and irregular contraction of the atria.

In AF, the heart’s electrical signal doesn’t begin in the SA node. Instead, the signal begins in another part of the atria and doesn’t travel through the normal pathways and it spreads throughout the atria in a fast and disorganized manner. This causes the walls of the atria to quiver very fast (fibrillate) instead of beating normally. As a result, the atria aren’t able to pump blood into the ventricles the way they should.

Ventricular arrhythmias start in the ventricles. They can be very dangerous and usually need medical attention right away.

Ventricular arrhythmias include ventricular tachycardia and ventricular fibrillation (v-fib). Coronary heart disease, heart attack, weakened heart muscle, and other problems can cause ventricular arrhythmias.

Ventricular tachycardia is a fast, regular beating of the ventricles that may last for only a few seconds or for much longer.
V-fib occurs when disorganized electrical signals make the ventricles quiver instead of pump normally. Without the ventricles pumping blood out to the body, a person will lose consciousness within seconds and die within minutes if not treated.

To prevent death, the condition must be treated right away with an electric shock to the heart called defibrillation.

For more information about arrhythmias, click here to go to the Resounding Health Casebook on the topic.

Congratulations to Dana for a job well done!

Michele R. Berman, M.D. was Clinical Director of The Pediatric Center, a private practice on Capitol Hill in Washington, D.C. from 1988-2000, and was named Outstanding Washington Physician by Washingtonian Magazine in 1999. She was a medical internet pioneer having established one of the first medical practice websites in 1997. Dr. Berman also authored a monthly column for Washington Parent Magazine.

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