1. What are PACs and PVCs?

Premature atrial contractions (PACs) and premature ventricular contractions (PVCs) are early beats that originate in the atria (PAC) or ventricles (PVC) of the heart. They briefly disrupt the heart’s autorhythmic beating. It feels like your heart “skips a beat.” Most people have them at some time in their lives, and they are somewhat common and normal in children and teenagers (AHA 2012b). If they become more regular, consult a health professional to determine a cause.

2. What is long QT syndrome?

Long QT syndrome is a defect in which the heart’s electrical cells take longer than normal to recover after each heartbeat. Long QT syndrome can be inherited or can be acquired after taking certain medications (or certain combinations of medications). People with long QT syndrome may be susceptible to ventricular fibrillation (rapid, chaotic quivering of the ventricles). During ventricular fibrillation, the blood pressure falls to zero and the person loses consciousness. An immediate, life-saving shock (defibrillation) must be delivered to the heart to restore a normal rhythm.

3. What is a heart block?

A heart block happens if the electrical impulses from the atria are not properly transmitted to the lower ventricular chambers. Different types of heart blocks may require different treatments, depending on exactly which part of the heart’s electrical-conduction system is faulty. Other symptoms–such as fatigue, lightheadedness or fainting–may develop. In some cases, implanting a permanent pacemaker (a device that artifically stimulates the heart muscle and regulates its contractions) is the primary treatment.

4. What is sick sinus syndrome?

Sick sinus syndrome is a cluster of symptoms that indicate the heart’s natural pacemaker, the SA node, is not functioning properly. The heart rate can switch back and forth between a slow (bradycardia) to fast (tachycardia) heartbeat. The condition may not be diagnosed until it has advanced, usually with age. A permanent pacemaker, sometimes in combination with medication, is the primary treatment.

5. What is sinus bradycardia, and when is it dangerous?

Any heart rate slower than 60 beats per minute is referred to as a sinus bradycardia. Many people, especially exercise enthusiasts and athletes, have a naturally developed sinus bradycardia as a result of their very efficient cardiovascular systems. However, if sinus bradycardia is accompanied by unusual fatigue, shortness of breath, decreased exercise tolerance, and episodes of nearly passing out, it may be necessary to implant a pacemaker.

To view the full article “Heart Arrhythmias: An Exercise Professional’s Primer” published in the November-December 2013 issue of the IDEA Fitness Journal click here.