A heart blockage, or heart block, refers to a condition where the heart beats too slowly; electrical signals typically initiating heart contractions become stuck between the upper and lower chambers. Heart blocks occur in several varieties, called degrees. Some, like first degree blocks, produce mild and even unnoticeable symptoms while third-degree blocks may completely prevent passage of electrical signals, causing noticeable symptoms. Regardless of block type, some risk factors increase the probability of developing a heart block, including valve abnormalities, history of heart attacks, certain medications, Lyme disease and older age.
In addition to having different names, the different heart block stages produce varying symptoms, and may derive from different causes. In a first-degree heart block, all electrical signals originating in the upper chamber eventually reach the lower chambers, but at a slower pace than normal. This heart block affects people of all ages, including athletes. It produces minimal symptoms, if any at all, and triggers from use of certain medicines and exposure to environmental toxins. According to Heart Rhythm Society, Type II heart blocks result when some electrical signals generated in the upper chambers never reach the lower chambers. This results in delayed or absent heartbeats, potentially causing serious harm. Some people with Type II heart blocks receive pacemakers. Type III heart blocks create more complete blockages, causing chronic fatigue and light-headedness. Lastly, bundle branch blocks prevent travel of electrical signals through heart tissues.