Like HowStuffWorks on Facebook!

Atrial Fibrillation Overview


You may be surprised to learn that atrial fibrillation, an abnormal heart rhythm, follows heart failure as the most common type of heart disease. More than 2.2 million people in the United States suffer from heart disease caused by irregular heart rhythm, and worldwide more than 5 million are affected.

Because risk increases with age, it is expected that the number of people over the age of 80 with atrial fibrillation will quadruple in the next seven to eight years. In this article you will learn what atrial fibrillation is, how it works, its potential dangers, and what causes it.

What are the Odds? Heart Attack

/* Discovernator - full and tiny */ .discovernator #factContainer { margin: 0 70px; -moz-box-shadow: 0 0 5px #a3ccea; -webkit-box-shadow: 0 0 5px #a3ccea; box-shadow: 0 0 5px #a3ccea; } .discovernator .tri { position: relative; z-index: 3; } /* full*/ .mainDiscovernator .RandomFact.module { margin-bottom: 0; } .discovernator.full { width: 825px; height: 570px; padding: 0 0 38px 0; background: url('http://static.howstuffworks.com/gif/heart-health-tips-background.png') no-repeat 0 0; } .discovernator.full h1 { width:515px; height:122px; background: url('http://static.howstuffworks.com/gif/heart-health-tips-big-title.png') no-repeat 130px 15px; } .discovernator.full h2 { width:498px; height:23px; background:url('http://static.howstuffworks.com/gif/heart-health-tips-subheading.png') no-repeat 50px 0px; } .discovernator.full .button { width:233px; height:51px; background: url('http://static.howstuffworks.com/gif/heart-health-tips-button.png') no-repeat 0 0; } .discovernator.full .tri { background-image: url (data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAEYAAAAlCAMAAADIkG9CAAAAulBMVEX////8/f72+v37/f7P5vP0+f2x1+zO5fOy2O3w9/u12e7y +Py83e/g7/j9/f74/P3l8Pi/3u/m8vjb7Pbe7ffF4PHE4PDL4/Pa7Pay1+3T5/Tt9fv9/v7W6vXM5fO02O293e/u9vuz2O3F4fHr9fr4+/3n8vnq9Pr +/v/Y6/X0+fz6/P3d7ffG4vG+3e/V6fXj8Pi52u7X6vXK4/K42u7B3/Dz +fzl8fjv9vvJ4/Lo8/nA3vC72+6w1uxDqvEIAAAAPnRSTlP//////////////////////////////////////////////////////////////////////////// /////ALr7cTYAAAEjSURBVEjHrdRndoJAFIbhQZEWiIDdaDSa3nt/97+t/OEkEgemyLeA58wtcwW/aQvr7IkmmHa8wbSsmRFNMD2aYFJKTNdOOZ6UGbsWHy0oM4 6NcrCizARWFQX8Yx4slLxQNpjMatJbzNoU2XeRMK6hcpkhY8Zmyv0KKfNmgjguyJl3k8MQU8F4+ts36wVUMUv9xV1CJaM7qK4PNUxfT0kW1DKh1nf +glomOlcj4Q0omEP1kEegZFIF0vFBzXhX9eX4HjrMRx3yOUCVgjmtPgdJDJpMNKtqyTwCbWYqf0g6QDMCwOvIBjyNwIjZXprWOMMkAuC1bJz0hxhGAE +ld1yvMY+AyV9nwotbrCJgXhyS3H/GNoJvRwjn7PGFXSJI8rshu+YHsJQatMLGNKcAAAAASUVORK5CYII=); } /* tiny*/ .discovernator.tiny { height: 304px !important; background: url('http://static.howstuffworks.com/gif/families-background-mini.jpg') no-repeat 0 0; } .discovernator.tiny h1 { margin: -8px -13px 0; width:300px; height: 82px; background: url('http://static.howstuffworks.com/gif/families-header-mini.png') no-repeat 0 0; } .discovernator.tiny h2 { margin: 6px auto 0; width:192px; height:30px; background: url('http://static.howstuffworks.com/gif/families-tagline-mini.png') no-repeat 0 0; } .discovernator.tiny #factContainer{ margin: -14px auto 0; height: 105px; } .discovernator.tiny #justthefacts li { padding: 16px 12px; height: 85px; } .discovernator.tiny #gimme { margin: 20px auto; } .discovernator.tiny .button { width:144px; height:31px; background: url('http://static.howstuffworks.com/gif/families-more-button-mini.png') no-repeat 0 0; } .discovernator.tiny .tri { background-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACcAAAAVCAMAAADyzwehAAAAw1BMVEX/// +12O39/f7U6PT9/v7k8fiy1+zE4fH8/f7f7vjv9vvH4vLW6fX4/P34+/3E4PG52+6x1+zO5fO93O7L4/Oy2O3R5/P+/v/f7vf9/v/x +Pzh8Pjv9vv3+/3F4fG32u6z2O2x1uy42u7A3u/Y6/XY6vX1+v3b7Pbo8/nm8vjc7PfM5PP6/f79/v7T6PTt9frg7/jW6vW72+7n8/m62+70+f283e/j8Pjv9/v a7Pbm8vnu9fvE4PDQ5/PG4vHA3vCw1uzLlOswAAAAQXRSTlP/////////////////////////////////////////////////////////////////////////// //////////ADBV7McAAAC2SURBVCjPhc/XDoJAFEXRQUMLKMWu2HvB3uv5/68yCEHKDLOfV27OJYLXlHA6EXjpHJYzfLfjOBu +G2WzPAJ347HAqVnbqgidyGZtDaGTNkw2M/F3woSh3LGFiCs16MzpAFG3pKpCvoK4W9DebO2BuJMe6WHiB0i6kpJUcwNIu3VilzoEKK7vRFVTNwGqk2shKl7eEs BwhwCt7vYArAie7u+S+DoiI9K7EsWpa11kR+Rt+WyB2xegSVyWUNqfMQAAAABJRU5ErkJggg==); } /* twitter button*/ #twitternator i { background: url("data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAC0AAAAoCAYAAABq13MpAAAGH0lEQVRYw +2Y30+TVxjHOTHOkUFCll0sXnFBNFmyhERvZrzo5S7J/APozW6WKU5BJz8LFkqopSDQX5ZSoFSkQPnpmNOBFGEotLQVms4RKlWrMClNxSb24ux53vZl/fECrh0/ sknyzVva857zeb/neZ7znpNCKU3ZSeScjEfy5Pz3aZusSJ4ih1xQGxnlKXhcbf5ufLYxO74DeQYpaLGQQj39pm1UkjTQ2SYeKHvL3y/c4JHiLkqEQ/TTmtveE9e HxdtCp15pW2AAzys3HU0r0VeRqp8ouTZKPxIOviEXm3OSgT5RNygmVzooKdBGjcPq4/Lu50Ryn5KmR5TUPWDgoW3LltBnuqbtRDRCSVkvNhwl +ZrMI5VDG6RhmhK5mRLpOD0s6PHDYBmJQj9+tZ57XGXyk+o7lAiMlPzY7iU/qASMy5da+aTmbmgspZUShYWS65MsuIATWmd/JmIaoQD +UOWwj9SOw81zlKhsoc6u/UpTyww6mEZjguBpjJOyGUoafmP6IxX9lBTdtHwiGn5Jrk +FgHE8lHKO4TkiHNhgHuz7hgwI48zIDrNO6ue8TEOm07DDbAconDYcSIDMibktefTUka6eC4bcnAvBozn1kyF3I8dDYRt80FIDPXRJa200PT4W1aHW/txAZLPhp 7RydGChuXeeuBdW/VOJQps962fSFA/fbfaPVzSKEceY7CxLTfQrzYTrS0nfKcbyiE6zc0ecbqYDjpvTVbPBP7wb +dDu8yQSMu27X5zOo632wJaQHGb1Lb62LPveYjXJSkktaNaR81Ab8+SZ5HIb7wv1pHXT7Zgbb9hePMJB/4V6zP/27hM7ZzjECgzMGXB40FB27JSlNb/gs8peMyn qpKQcMloyFhfL6c3WoGT2mQNuOP3Pa3NjNiiu4vy8uJJ/VGPe0W2cXdPyWnVs9UB6qeShy3FcO +Nnki0cHukaWzDn9hPP4z/f3IM2XyfoatbhgpZxWOGkuMLBjPLIRTU/VTjwgKlU20Bjwo65vfdjwzGyc4S6ARqN0CDocpIxnPLM91Z2UnlvCisAIyxz4nuhasQF Dd8d1doCYeCsLReXXRbO5uW+319ZTnaYvUyZYxeRGNjj+nm/xPwCQ/EmF/BeQm9WJwzFlbfvTFgNzt13LZ0bf7qEV83Cin3h9cZUeLa3DcW9ho50Hh +AH6HT7xuG+wWdlD5Af4D+X0IXFxfzSkpK +AcOuqioKG7vBqAZQqHQUlNTQ7u7uyUHDrq6unoBAcvKyjYdFYvFVXK5nGo0GtrU1PSmoqIi50BBDw0N2RUKBa2rq6MAP3r16tVMmUy2odfrqcFgoK2trbS +vt4PD5VxYKCdTqdIp9NRlFKppADs02q1GBa0t7eXAUfHpVKpTiAQGA9KImYNDw97e3p66K1btyjrMAKz6uzsZMDBcbpbQKWlpTnl5eVGFHzm7Vg9wG1DV1cXA4 jwkcCs25OTk+61tbWE9ohYhUBbHtbADPIkEgnmD1WpVN6Wlhbuw5rCwsKoPeLExISbCxgFoRL0+XwJ7xHVarUYEp7GJjwryKfnGJI4o +3t7Qw8tI0/rIEvdTglUN4yq6qqeOCmlXU71mWYiaT2iKurq7kQen5wkQkxkUjkBXeZgxgYmw8PxYyDpuEV8ysMHn1Ys76+LmhsbDRDeWM6gimJi2Wj0Ricn59P aI8Y +0qKTrI5g/nR0NBAYWwLlNaXHR0dUWGJn8PgzGENRgWsJ5mbe0Sbzebo6+vzY4fsjf39/UGTyeTxer3J7BGjZLfbHWgCjoGVCeHxQRAu1qxwSDK/19bW0srKSuv 09PSxPdkjRmplZeUMhN871hi8Roorl/Bh2tra8OqCcnxqX3YtUIGcg4ODga0guaCXl5ctfr8/dFizTwsEH8DtXOEQK3ywsbGx6MOa3QbEFzFQ3NIPzuVDbO/oNv we9Hg81Xv9Pp0FJWscVjgprnBQWnnw4sWHivUAk287aExYAN72sGbXBLEog3I2hRUAhWWuubmZRlaq2JAYGBgIhIH397DG5XJZIAG97HtNLDD +PzIy4nfA34E7rAkEAia3222ZmZlZmp2dXcLr4uKiHRa6/+5hzV9kwTJynia+aQAAAABJRU5ErkJggg==") no-repeat -24px 0; height: 18px; width: 20px; margin-left: 8px; }