What is second-degree heart block?
In this condition, some signals from the atria don’t reach the ventricles. This causes “dropped beats.” On an ECG, the P wave isn’t followed by the QRS wave, because the ventricles weren’t activated. There are two types: • Type I second-degree heart block, or Mobitz Type I, or Wenckebach’s AV block. Electrical impulses are delayed more and more with each heartbeat until a beat is skipped. This condition is not too serious but sometimes causes dizziness and/or other symptoms. • Type II second-degree heart block, or Mobitz Type II. This is less common than Type I but generally more serious. Because electrical impulses can’t reach the ventricles, an abnormally slow heartbeat may result. In some cases a pacemaker is needed. What is third-degree or complete heart block? Complete heart block (complete AV block) means that the heart’s electrical signal doesn’t pass from the upper to the lower chambers. When this occurs, an independent pacemaker in the lower chambers takes over. The ventricles
