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atrial fibrillation

Responding to a different beat

Each year, for “American Heart Month,” I have conducted a Q & A interview with noted cardiologists on various heart-related topics. My quest this year was to find an up-and-coming younger cardiologist with grey hair still in his or her future.

I did what physicians always do when they have a tough case or need to find who is good at what. I shared my dilemma with fellow colleagues over lunch in an Uptown hospital doctor’s dining room.

“You need to look up Paul Stahls,” said fellow internist Dr. Robert Miles. “I met him when he was doing his residency at Ochsner. He went into cardiology, and I think he’s practicing on the Northshore. Paul is one of the most intelligent persons to go into medicine I have ever met. “

Such a recommendation by Dr. Miles was not one to be ignored. I Googled Dr. Stahls, called his Covington office and explained the mission, and he agreed to an email interview, which I condensed, edited and is printed below. Dr. Paul Stahls is a cardiologist with additional training and expertise in electrophysiology.

What are the most common problems treated by a cardiologist with special expertise in electrophysiology? Disturbances of the normal electrical conduction of the heart; we call them arrhythmias.

Where does atrial fibrillation fit into the scheme of things? Atrial fibrillation is the most common arrhythmia of the heart and bears a stroke risk secondary to inefficient emptying of the top chambers of the heart.

Is it true all the folks with atrial fibrillation in the United States equal the population of Louisiana? Almost. There are approximately 2 to 3 million Americans currently diagnosed. With the general population surviving longer, the prevalence of this disease is estimated to affect 5 to 6 million Americans within the next 10 years. With those numbers you could fill up Louisiana and have some spill over into Mississippi.

Are some folks more likely to develop atrial fibrillation than others? Yes, the associated risk factors for developing atrial fibrillation are obesity, obstructive sleep apnea, hypertension, valvular heart disease and heart failure. Obesity is a risk factor for most cardiovascular diseases and is one that is controlled by the patient. Exercise and a healthy diet are key elements to a healthy heart and reducing the risk of all of the disease processes that affect it.

Why the increase in atrial fibrillation? There is an increased prevalence with age, and its disease progress is related to the aging heart. It is sometimes not directly avoidable, but there are certain measures that every patient can take to minimize their risk of developing this disease.

Thump, thump: the heartbeat. What is actually going on? The normal heartbeat occurs in two phases. The first is the squeezing and contraction of the thin walled top chambers of the heart called the atria, and the second phase takes place when the stronger walled ventricles contract.

And what happens during each cycle?

The left atrium collects oxygenated blood from the lungs under low pressure and passes it on into the left ventricle, a more muscular chamber that squeezes with the force to send oxygen containing blood to all your tissues from your head to your toes. Blood depleted of oxygen returns from the venous drainage canals to the right atrium and then to the right ventricle, a lessor pump but with the power needed to move blood into the lungs for an oxygen load and return it to the heart’s left atrium.

And where do electrical impulses come into play? The coordinated pumping actions involving all four chambers of the heart are coordinated via the heart’s wiring system. These are wires made from cells that begin to generate electrical impulses as we develop in the womb and direct the activity of our heart throughout our lives.

Where does atrial fibrillation fit into all of this? Atrial fibrillation is an electrical storm of irregular activity that arises from the top chamber on the left side of the heart and takes over the usual rhythmic actions of the normal conduction system. This electrical chaos results in quivering, non-contracting top chambers that inefficiently deliver blood to the bottom chambers of the heart. This results in a lack of the coordination of blood moving through the heart and leads to the symptoms related to atrial fibrillation.

What are the symptoms? The primary symptoms are palpitations or extra beats, shortness of breath and lack of energy. These are then assessed using electrocardiography, and with only 30 seconds of sustained arrhythmia the diagnosis of atrial fibrillation can be made. But at least a third of persons in atrial fibrillation do not feel any symptoms, and the irregularity often goes undetected.

So if no symptoms, why worry? Atrial fibrillation is a major stroke risk factor. The risk for stroke increases when combined with other major risk factors: congestive heart failure, hypertension, age greater than 75, diabetes and a previous stroke. A physician can assess all your risk factors for stroke and determine the best strategy to reduce those risks.

Tell us more about how sleep problems affect heart rhythm? Obstructive sleep apnea is a major contributing factor to the development of atrial fibrillation. Even when snoring and episodes of staggered breathing while sleeping are recognized, sleep apnea is often not properly diagnosed and even less often treated.

     With sleep apnea there is less airflow into the lungs. A lowered blood oxygen level sends a pending suffocation alert to the brain. The brain reacts with a release of stored adrenaline that increases blood pressure and heart rate so more blood can get to the tissues. This excess adrenaline release disrupts the sleeping brain, changes its activity level and affects fat metabolism leading to increased pounds. All this feeds into other wear and tear risk factors to increase the risk for developing atrial fibrillation.

And high blood pressure and heart valves? Hypertension creates a disruption of the pressures in your main pumping chamber that is then reflected back into the top chambers of heart, increasing the pressure of the blood and resulting in a stretching of the tissue with resultant scarring, not dissimilar to stretch marks that occur on skin in different parts of the body. It is this scarring in the top chambers of the heart that lead to changes in the electrical properties.

   Diseases of the valves and weakening of the heart muscle result in a similar change in pressures within the chambers of the heart and lead to the same kind of stretching and scarring that hypertension does.

Can atrial fibrillation be treated? Yes. Once diagnosed, the management of atrial fibrillation needs to be tailored to each patient specifically. There are primarily two kinds of medication used in the management of this arrhythmia. There are agents that are more effective at keeping the heart in normal rhythm, and others that are made to help control the rate of beating of the bottom chambers of the heart. These two kinds of drugs can be used in conjunction with suppression of atrial fibrillation for some patients. Other patients don’t tolerate taking these medications well and require other therapies.

What have physicians prescribed for patients with atrial fibrillation over the years to reduce the stroke risk? An aspirin a day reduces the stroke risk by itself for persons with one or none of the above listed risk factors. Persons with two or more risk factors require stronger blood-thinning medicines. Coumadin was essentially the only ball game in town for chronic anticoagulation from the 1950s until 2010. It is a well-studied drug and when used and monitored carefully can be safe. There is an increased risk of bleeding when using Coumadin, but there’s an antidote and a well-established series of medicines that can be used to reverse its effect when clinically indicated.

And the new blood thinning kids on the block? Pradaxa, Xarelto and Eliquis. These newer alternatives to Coumadin were developed in the hopes of better reducing the risk of strokes from atrial fibrillation while reducing the incidence of worrisome bleeding adverse effects. Persons on blood thinners are at higher risk for hemorrhagic strokes and other serious complications, especially after even minor trauma. These new drugs are also associated with these increased bleeding risks, and antidotes and reversal agents are being developed for these medications.

When does an elective cardioversion fit in? Why not just shock the heart back into a normal rhythm? Shocking the heart simply allows a temporary return to normal electrical activity. It is an important tool utilized in the management of atrial fibrillation, but the normal pacing is usually time-limited, especially for a person who has had atrial fibrillation for years.

I like the term ablation. How does it fit into heart care? Most of the cells responsible for atrial fibrillation are within and around the left atrium and pulmonary veins. When these cells turn rogue, we can often take them out by intentional scarring or decrease their damage by isolating the abnormal cells from normal signaling tissue. The primary alternative to medications for control of atrial fibrillation is ablation. It is akin to seek and destroy, with a focus of destroying or isolating the nest of abnormal cells causing the electrical chaos.

We all know the military seeks and destroys to eliminate or paralyze enemy forces. How do the cardiologists do it? We burn or freeze the tissue that has run amok, but first we need a map. An electrophysiology (EP) study gives the data we need to map the cardiac electrical pathways looking for the trouble spot. The EP study starts with the floating of a long, thin catheter from a vein in the groin to electrical impulse business center in the heart. This gives up the needed intelligence to decide on the best treatment.

For the person with simple on-and-off episodes of atrial fibrillation, first attempt success rates approach 80 percent. Often times, a second pass is needed. The procedure itself lasts three to six hours and requires only a one-night stay in the hospital and a short recovery time as an outpatient.

So what is the bottom line on atrial fibrillation? Atrial fibrillation is a consequence of a lifetime of accrued risk factors and age-related wear-and-tear changes. Its symptoms can range from none to a life filled with the results of a debilitating stroke, shortness of breath or decreased ability to exercise. Once diagnosed, appropriate risk reductions for stroke must be instituted and the specific management of the rhythm should be addressed with consultation with an electrophysiologist. Understanding what you can do to reduce your risk is important to avoid this disease and all others related to the cardiovascular system. 

 

 

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