aortic valve real estate

Sunday, November 3, 2013

Football is all about real estate. The offence wants the next ten yards for a first down; the defense wants to deny them. Touchdowns and first downs can come down to a matter of inches. Today, though, for John Fox, Denver Bronco head coach, the most important parcel of real estate happens to be located in his heart, specifically in his aortic valve and is measured in tenths of centimeters.

A week off from the NFL during the season allowed Mr. Fox to go golfing, but on the course he became lightheaded. That led to a trip to the ER where he was found to have worsening of an already diagnosed heart valve and now he is facing surgery to replace the worn valve. What was a manageable and treatable condition has become life threatening and an operation that was relatively elective has become more urgent.

The aortic valve is located at the junction of the left ventricle and the aorta. When the heart pumps, the left ventricle sends blood into the aorta where it is distributed to the rest of the body. The aortic valve is a one way valve, opening to let blood out of the heart and closing to prevent backflow.

aortic valve

In some people, the thin and pliable leaflets of the valve start to stiffen and degenerate and the area where blood can flow narrows, just like a rusty pipe. As the diameter of the valve narrows, the amount of blood that it lets through decreases and eventually may not need the needs of the body. This can lead to shortness of breath on exertion, chest pain or lightheadedness, if the brain doesn’t get enough blood. In Mr. Fox’s case, it was the lightheadedness. As an aside, patients may complain of dizziness and it’s important to make the difference between lightheadedness and vertigo, where the room spins, and is not usually heart related.

The most common cause for aortic stenosis is gradually degeneration and narrowing of the valve because of calcium deposits. The same risk factors for heart disease are in play for this: high blood pressure, high cholesterol, diabetes and smoking. Quick tangent history note: Rheumatic fever due to strep throat infections used to be a major cause of heart inflammation and valve damage, but now is rarely seen in North America because of widespread antibiotic use.

Many patients know about their heart murmur, are followed routinely by their doctor and may never need any intervention. The initial diagnosis is often made incidentally, when a health care provider listens to the heart and hears a heart murmur, the sound of turbulence when blood tries to get through the narrowed space. This may lead to a variety of tests including an EKG and echocardiogram, but history and physical exam is still of prime importance because it’s all about function. Many patients have heart murmurs and have no issues with performing daily life activities and exercising.

It may take 10-20 years for aortic stenosis to be present before symptoms arise. Almost a third of people older than age 65 have some element of aortic stenosis. It is when there is a change in performance that the patient and the doctor need to take action.

Echocardiography, or ultrasound exam of the heart, can monitor and measure the diameter of the valve and the velocity of the blood flowing across the valve. A normal valve is at least 1.5 square centimeters in area (0.25 square inches or ½ inch by ½ inch). A severely stenosed or narrowed valve has an area of less than 1.0 square centimeter (0.15 square inches) and it’s critical when the valve is less than 0.5 square centimeters. How fast the blood flows across the valve is also important. Just like a hose or pipe, the narrow the diameter, the faster the flow but also the more pressure that needs to be generated to get the blood past the obstruction. This leads to hypertrophy, thicker muscle in the left ventricle, with its own set of problems.

For those many patients whose valves gradually narrow and whose daily functions are not affected, the treatment is aimed at maintaining normal lifestyle. When symptoms occur, surgery may be an option and what type depends upon the patient’s underlying condition. For younger (relatively), healthier patients, replacing the valve is an option.

Mr. Fox was aware of his aortic valve issues but it did not prevent him from pursuing a stressful career as a head coach and it did not stop him from golfing. The idea that he delayed surgery is not quite right. His body was going to tell him when the time was right for that surgery to occur. And who said football was a game inches.

 

Illustration: aurorahealthcare.org

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