A second degree heart block is an interruption of the electrical pulses between the chambers of the heart. This occasionally results in skipped heart beats. Heart blocks are relatively rare but, according to the U.K's National Health Service, serious second and third degree blocks are found in one out of every 30 people with heart failure and may require a pacemaker. While generally heart blocks have few symptoms, physical activity can exacerbate them.
Types
There are two types of second degree heart blocks. Type I, or Wenckebach blocks, are the less serious of the two. According to the University of Nevada School of Medicine, Wenckebach blocks may be caused by medications such as beta blockers or abnormalities like fibrosis or ischemia. Type II blocks are likely caused by the same issues that eventually cause heart attacks and are a warning sign for future heart issues. Type I blocks usually do not require treatment, while type II blocks are often treated by installing a pacemaker.
Dizziness
Dizziness is a symptom of both types of second degree heart blocks. Exercise makes this symptom worse as your heart rate climbs to meet oxygen demands of your muscles. The chances of missing heart beats or the block interfering with getting the blood out of the heart and into your working muscles increases along with your heart rate. If your heart cannot meet these demands, blood may be diverted from your brain to your muscles, which causes dizziness. If you feel dizzy while exercising, bring your heart rate down gradually by lowering your intensity.
Fatigue
The increased demands exercise put on the body may cause extreme fatigue. Since a heart with a second degree blockage might have to work harder than normal to meet oxygen demands, even moderate intensity physical activity can be exhausting. Fatigue may also be accompanied by confusion and muscle weakness. Be sure to know your limits during exercise and not to push yourself to an unsafe level. Exercise sessions monitored by an exercise physiologist can help teach you your limits.
Shortness of Breath
Shortness of breath may also occur with exercise if you have a heart block, though it is usually only seen with type II blocks. If you feel you cannot catch your breath during physical activity, or feel tightness in your chest, cool down immediately. Cooling down properly is important to prevent blood pooling and to allow your heart rate to gradually return to normal. See your doctor before returning to exercise, as these symptoms could indicate other problems.
