Drew Pickett, MD: electrophysiologist (cardiologist)
Monday, February 20, 2012
TOPIC: Advances in A-Fib
News notes via www.webmd.com and other additional resources
DID YOU KNOW…16 million: The estimated number of Americans who will have atrial fibrillation (AF) in 2050, up from 6 million today
The Watchman Study: a device alternative to warfarin (Coumadin) therapy
Dr. Drew Pickett, is the ONLY cardiologist in Tennessee enrolling patients in the Watchman Study via the Saint Thomas Research Institute
Atrial fibrillation (AF) is the most common type of sustained irregular heartbeat. It affects approximately 6 million U.S. adults, mainly those ages 65 and older. As the population continues aging, that number is expected to rise to almost 16 million by 2050. This growing prevalence lends increased urgency to the search for additional ways of preventing stroke, the most devastating complication of AF. The Watchman® Left Atrial Appendage (LAA) Closure Technology device may offer a new option for stroke prevention.
The current most common treatment for stroke prevention in people with AF is a prescription for warfarin (Coumadin), an oral anticoagulant. However, there are several major drawbacks to warfarin therapy. An increased risk of serious bleeding means that warfarin may be contraindicated for some people, including older adults who are at high risk for falls. In other cases, warfarin may still be prescribed, but the risk of dangerous bleeding means that people may be advised to curtail activities they once enjoyed, such as skiing and other sports in which falls are common.
It takes careful calibration to find the safe and effective dose for a particular patient, and monthly blood draws to monitor blood levels of the drug are required indefinitely. Warfarin also interacts with a number of prescription and over-the-counter medicines, such as antibiotics, salicylates, nonsteroidal anti-inflammatory drugs, beta-adrenergic blockers, diuretics, antidepressants, diabetes agents, and gastric acidity and peptic ulcer agents. Drug interactions can be problematic for older adults, who are often taking multiple medications. In addition, certain foods interfere with how warfarin works, which necessitates some dietary restrictions, such as limiting green leafy vegetables, Brussels sprouts, and broccoli.
Atrial Fibrillation and Heart Disease
What Is a Normal Heart Rhythm?
The heart has four chambers, or areas. During each heartbeat, the two uppers chambers (atria) contract, followed by the two lower chambers (ventricles). This action is directed by the heart's electrical system.
The electrical impulse begins in an area called the sinus node, located in the upper part of the right atrium. When the sinus node fires, an impulse of electrical activity spreads through the right and left atria, causing them to contract, forcing blood into the ventricles.
Then the electrical impulses travel in an orderly manner to another area called the atrioventricular (AV) node and HIS-Purkinje network. The AV node is the electrical bridge that allows the impulse to go from the atria to the ventricles. The HIS-Purkinje network carries the impulses throughout the ventricles. The impulse then travels through the walls of the ventricles, causing them to contract. This forces blood out of the heart to the lungs and the body. The pulmonary veins empty oxygenated blood from the lungs to the left atrium. A normal heart beats in a constant rhythm -- about 60 to 100 times per minute at rest.
What Is Atrial Fibrillation?
Atrial fibrillation (also referred to as AF or Afib) is the most common type of irregular heartbeat. It is found in about 2.2 million Americans. It increases with age. If you have AF, the impulse does not travel in an orderly fashion through the atria. Instead, many impulses begin simultaneously and spread through the atria and compete for a chance to travel through the AV node.
The firing of these impulses results in a very rapid and disorganized heartbeat. The rate of impulses through the atria can range from 300 to 600 beats per minute. Luckily, the AV node limits the number of impulses it allows to travel to the ventricles. As a result, the pulse rate is often less than 150 beats per minute, but this is often fast enough to cause symptoms.
What Are the Symptoms of Atrial Fibrillation?
You may have atrial fibrillation without having any symptoms at all. If you have symptoms, they may include:
What Causes Atrial Fibrillation?
Atrial fibrillation is associated with many conditions, including:
Less Common Causes of Atrial Fibrillation
Less common causes of atrial fibrillation include:
In at least 10% of people with AF, no underlying heart disease is found. In many of these people, AF may be related to alcohol or excessive caffeine use, stress, certain drugs, electrolyte or metabolic imbalances, or severe infections. In some people, no identifiable cause can be found.
The risk of AF increases with age, particularly after age 60. According to the CDC, AF affects roughly one in every 10 persons aged 80 years or older.
Why Is Atrial Fibrillation Dangerous?
Many people live for years with atrial fibrillation without problems. However, because the atria are beating rapidly and irregularly, blood does not flow through them as quickly. This makes the blood more likely to clot. If the clot is pumped out of the heart, it can travel to the brain, resulting in a stroke. The likelihood of a stroke in people with AF is five to seven times higher than in the general population. Although about half of all blood clots related to AF result in stroke, clots can travel to other parts of the body -- such as the kidney, heart, or intestines -- also causing problems.
AF can also decrease the heart's pumping ability by as much as 20%-25%. AF combined with a fast heart rate over a period of days to months can result in heart failure. Control of AF can then improve heart failure, also over days to months.
Chronic atrial fibrillation is associated with an increased risk of death.
How Is Atrial Fibrillation Diagnosed?
Four tests are used to diagnose atrial fibrillation, including:
These monitoring devices help your doctor learn if you are having irregular heartbeats, what kind they are, how long they last, and what may be causing them.
How Is Atrial Fibrillation Treated?
Many options are available to treat AF, including medication, lifestyle changes, certain procedures, and surgery. The choice of treatment for you is based on your rhythm and symptoms. The goals of AF treatment are to:
Lifestyle Changes for Atrial Fibrillation
In addition to taking medications, there are some changes you can make to improve your heart health and help atrial fibrillation.