Thursday, February 24, 2011

Atrial Fibrillation and YOU

Based on my talk at the St. Armands Key Lutheran Church, February 23, 2011
Many of you may have heard the term atrial fibrillation. It is a very common condition that I as a cardiologist see in my daily practice. It is a disorder of the heart rhythm. If you feel your pulse either at your wrist or on the side of your neck just under the jaw bone, you will notice a nice regular rhythm to your heart beat if your heart is in rhythm. A normal resting heart rate usually ranges 60-90 beats a minute.

What is atrial fibrillation?

In atrial fibrillation, the heart rate can change from minute to minute and the regularity is lost due to a malfunction of the electrical system of the heart. Before we get into the specifics of this condition, we first have to understand how the heart works. Compare the heart to a house. A house has rooms, the heart has chambers (four). A house has a main electrical switch and wires carrying electricity, the heart has a main switch or the natural pacemaker which triggers an impulse leading to a heartbeat. A house has plumbing, the heart has plumbing in the form of blood vessels supplying the heart muscle. If you have a defective power outlet or a short circuit in your house and you call an electrician, the electrician is not going to fix it till the entire wiring of the house is known including the location of the main power switch. The electrical impulses in the human heart are generated in the main switch called the sino-atrial node that produces an electrical impulse that is carried to all the cells of the heart, triggering the heart to beat 60-80 times a minute.

The heart has four chambers, two upper and two lower chambers. The main switch or the sino-atrial node is located on top of the two upper chambers. When it turns on and fires an electrical impulse, this impulse is carried via small wires to the cells of the upper chamber. These cells squeeze simultaneously resulting in a contraction of the upper chambers of the heart and this pushes blood into the respective lower chambers of the heart. From the cells of the two upper chambers, this electrical impulse then travels to a secondary switch or the atrio-ventricular node. This secondary switch is located between the upper and lower chambers of the heart. The electrical impulse stops here for a fraction of a second and this allows the lower two chambers of the heart to fill up with blood. From this secondary switch or the atrioventricular node, two wires or nerve bundles carry the electrical impulse to the right and left lower chambers. This triggers the lower two chambers of the heart to contract simultaneously resulting in ejection of blood from the heart.

Since the human heart beats over 100, 000 times a day, think of how many on and off cycles the main power switch or the natural pacemaker of the heart has to endure. Nature has built in redundant mechanisms in the heart in case this natural pacemaker stops working. In fact, every cell of the heart has the potential to generate electricity and trigger the heart muscle squeeze and pump blood. When the cells of the upper chamber of the heart start firing in a random disorganized fashion, it overwhelms the natural pacemaker of the heart. Since there is no one dominant impulse orchestrating the conduction of electricity to all cells of the heart, the lower chambers of the heart receive impulses in random fashion, leading to the generation of an irregular heart beat. This leads to quivering of the muscles of the upper chambers of the heart. This irregular heart beat can last anywhere from minutes and hours to several years and in some cases it can be a permanent lifelong phenomena. This irregular heart beat is referred to as atrial fibrillation.

What causes atrial fibrillation?

High blood pressure is a common predisposing factor. Structural damage to the heart is the most common cause. One form of structural damage is a heart attack that causes weakening of the heart muscle. Damage to the heart valves is another form of structural damage. Heart valves are flexible flaps of tissue that regulate the flow of blood between the upper and the lower chambers of the heart. The valve between the left upper and lower chambers of the heart called the mitral valve is commonly involved in the genesis of atrial fibrillation. If the mitral valve does not close fully, it leads to back washing of blood from the lower to the upper chambers of the heart. If the mitral valve does not open fully, the upper chamber does not completely empty into the lower chamber of the heart. Both these situations leads to enlargement of the left upper chamber of the heart. When this happens, the cells stretch and this results in pockets of cells forming scar tissue. This scar tissue results in disordered propagation of electrical impulses leading to atrial fibrillation.

This process of scarring can extend to the main switch (sino-atrial node) or the secondary switch (atrio-ventricular node). This results in a condition called sick sinus syndrome, where the natural pacemaker of the heart does not function properly. This is another potential cause of atrial fibrillation.

Other causes of atrial fibrillation are exposure to stimulants in the form of medications, drugs and alcohol. An overactive thyroid can trigger the heart to beat chaotically. Previous heart surgery can cause structural changes in the heart predisposing to atrial fibrillation. Lung diseases such as emphysema, stress from pneumonia, surgery and illnesses can make the heart to go into atrial fibrillation. Age is a risk factor. Risk of atrial fibrillation increases with advancing age.

Sleep apnea or disordered breathing during sleep is another important factor that can predispose the heart to go out of rhythm.

Complications of atrial fibrillation

In general, atrial fibrillation is a non life threatening situation. A lot of people with this do not feel it at all. The two main consequences of atrial fibrillation are stroke and weakening of the heart muscle leading to heart failure.

The left side of the heart supplies blood to all parts of the body including the brain via blood vessels. There is a small pouch in the left upper chamber and the muscles of this pouch only squeeze when the heart is in normal rhythm. If the upper chamber of the heart beats chaotically as happens in atrial fibrillation, blood stagnates in this little pouch and blood can then coagulate leading to a blood clot. This blood clot can then travel to any part of the body through the network of blood vessels. If it goes up to the brain, it may lead to a stroke.

When the heart is not in rhythm, the chambers of the heart do not beat in sync. When the heart rate goes up and the heart is out of sync, there is incomplete filling and emptying of the heart chambers. The net result is that the blood is not efficiently pumped forwards and it backs up in the lung leading to congestion and fluid build up in the lungs. This is called congestive heart failure.  


A simple way to diagnose atrial fibrillation is to capture the electrical impulses produced in the heart on paper. This is called an electrocardiogram, This gives you the rate and regularity of the impulses coming from the upper and lower chambers of the heart. Atrial fibrillation shows up as an irregularly irregular rhythm on an electrocardiogram.

To rule out structural problems with the heart, we commonly use an ultrasound device to send and receive sound waves from the heart. This give us information on the structure of the heart, including the function of the valves of the heart. This test is called an echocardiogram.


Once you diagnose atrial fibrillation, the principles of treatment are as follows.

1. Control the heart rate. This is easily achieved with medications such as beta-blockers, calcium channel blockers and digoxin.

2. Control the rhythm. This is achieved with medications or a brief electrical shock to reset the heart back into normal. A newer invasive procedure called pulmonary vein isolation or ablation may also be considered in select cases. Once regular rhythm is established, a class of medications called antiarrhythmics may be used to keep the heart in normal rhythm.  

3. Decrease the risk of blood clots and stroke. Formation of blood clots in the upper chambers of the heart is easily preventable by administering blood thinning medications. The mainstay was a medication called warfarin. A newer medication called dabigratran was just approved by the FDA. This as effective as warfarin and has the advantage of not requiring routine blood tests that warfarin requires.

Sleep apnea and heart rhythm problems

More recently, there is evidence that sleep apnea is an important factor that complicates the treatment of atrial fibrillation. Sleep apnea is also referred to as sleep disordered breathing. In sleep apnea, there is interruption in breathing resulting in stoppage of breath for seconds to minutes at a time. Besides pauses in breathing, there can also be abnormally low breathing as well.

There are two main types of sleep apnea.

1. Central. The brain has control centres that regulate respiration. The main drive triggering this center is blood levels of carbon dioxide. In central sleep apnea, the control mechanism regulating the breathing process is defective and this leads to pauses in breathing.

2. Obstructive. As the name suggests, there is obstruction to airflow during sleep. During sleep, the muscular tone of the body relaxes during sleep. This relaxation of muscle tone during sleep can cause the muscles and soft tissue in the region of the throat to collapse and result in temporary obstruction to airflow.

Most of the cases of sleep apnea are caused by the obstructive mechanism (84%), followed by mixed obstructive/central (15%) and pure central mechanism (0.4%).

How does sleep apnea cause heart rhythm problems?

Sleep apnea has been shown to increase the risk of elevated blood pressure, stroke, heart disease and heart rhythm problems like atrial fibrillation. During episodes of sleep apnea, there is temporary cessation of breathing. This results in decreased levels of oxygen in the blood. This triggers the sympathetic nervous system which is also called the “fight or flight response”. This stimulates the heart. The variation of oxygen levels can trigger heart rhythm problems.

Traditional treatment of sleep apnea

Treatment options for sleep apnea include lifestyle changes, avoiding alcohol and sleeping pills, which can relax the muscles in the throat area. For more serious cases, a CPAP machine is used. In some selected cases, surgical options may also be utilized.

Alternative approaches to the treatment of sleep apnea

A recent randomized controlled trial1 found that learning and practicing on traditional wooden trumpet called didgeridoo can decrease the incidence of obstructive sleep apnea. It works by strengthening muscles in the upper airway, which prevents airway collapse resulting in sleep apnea. This requires mastery of a breathing technique called circular breathing. Circular breathing involves simultaneous breathing in through the nose while breathing out through the mouth with the cheeks puffed out. It is practiced by musicians who use a wind instrument like a trumpet and this type of breathing helps produce a continuous tone. This type of breathing is difficult at first.

Before practicing this type of breathing, one has to first increase the lung capacity. This is best achieved by practicing abdominal breathing.

Let’s try a little exercise that will help you gain awareness of your breathing and will help you increase your lung capacity. I will take you on a guided tour of your respiratory system. Please follow along.

Please close your eyes and sit comfortably.

Run a mental checklist and scan your body for areas or pain or discomfort. If you feel pain or discomfort in any part of your body, contract and relax the muscles in that area.

Feel the weight of your feet on the floor and keeping your back as straight as possible, feel your weight on the chair. As you do this, you are letting go of tensions in your body, your muscles relax and your body feels heavier.

Bring your attention to your nostrils and observe your breath. There should be no change in your breathing pattern. You are only watching the incoming and outgoing breathing.

If you find your mind wandering, gently bring your attention back to your nostrils. I will take you on a guided tour of your respiratory system.

Feel your breath going in and out of your nostrils. With each inhalation, feel your nostrils expanding and with each exhalation, feel your nostrils contracting. You are not forcing the breath, you are only watching it, feeling it.

Gradually move your attention to the back of your mouth. Once your attention settles at the back of your mouth, feel your breath moving in and out. Your attention is focused on the back of your mouth. With each breath coming in, feel your mouth expanding and with each breath going out feel your mouth contracting. Continue watching your breath with your attention at the back of your mouth.  

Now slowly move your attention to your throat. Gradually start to feel your incoming and outgoing breath in your throat area. With each incoming breath, feel your throat expanding outwards and with each outgoing breath, feel your throat contracting inwards.

Nothing is forced. You are only silently observing your breath going in and out with your attention fixed on your throat area.

Now take your attention down from your throat to the center of your chest. Again, you are a silent spectator to what is going on inside you. You are watching the incoming and outgoing breath with your attention fixed on the center of your chest. With each breath going in watch your chest expanding outwards and with each breath going out watch your chest move back inwards. Continue watching your breath with your attention on the center of your chest.

Now, let your attention drift downwards to the upper part of your abdomen. With each breath going in, watch the abdomen expand outwards and with each breath going out watch the abdomen move back inwards. Continue watching the breath with your attention on the upper part of the abdomen.

Now you are doing abdominal breathing. With each breath going in, your diaphragm is moving down pushing your abdomen outwards and with each breath going out, the diaphragm rises pulling your abdomen inwards.

Now, let’s travel back upwards. Bring your attention to the center of your chest again watching your breath go in and out. Travel up to the area of your throat and watch your breath.

Now forget the breath and take your attention to point between your eyebrows. Let your breath proceed on its own. Simply try to focus your attention at the point between your eyebrows.

From here take your attention further inside towards the back of the head. As you near the back of your head you will reach the Medulla Oblongata, the center in your brain that controls the breathing process.

Rest your attention here as long as you feel like and gradually open your eyes.


1.Puhan MA, Suarez A, Lo Cascio C, Zahn A, Heitz M, Braendli O (February 2006). "Didgeridoo playing as alternative treatment for obstructive sleep apnoea syndrome: randomised controlled trial". BMJ 332(7536): 266–70.