|How valves work|
|How valves work|
The human heart is an efficient muscular pump that has four chambers (two atria and two ventricles), each closed off by a valve—a strong, tissue-paper-thin leaflet. The valve acts like a gate that opens in response to the pressure exerted by blood pooling within the chamber. Once the blood has flowed through, the valve closes again.
To a toddler, a balloon is an object of delight; to a person with valve stenosis, or blocked heart valves, it can be a lifesaver when used in an angioplasty-like procedure called balloon valvuloplasty. An alternative to open-heart surgery, this procedure also can be used to correct narrowing of the aortic valve.Recognizing stenosis
Valves ensure that blood flows properly through the chambers of the heart. When narrowing heart valves make this flow difficult, the heart’s cells are slowly starved. Early symptoms of valve stenosis are fatigue and shortness of breath; later on, chest pain, dizziness and fainting may occur. Left untreated, aortal valve stenosis eventually leads to angina (chest pain) and congestive heart failure.Possible causes
Valves narrow for various reasons. Some babies are born with malformed valves, and rheumatic fever in childhood can damage the flaps of the mitral valve. Heart walls often thicken with age, causing valve flaps to stiffen. Sometimes calcium deposits prevent valves from opening all the way.A quick fix
In valvuloplasty, a balloon, attached to a catheter, is threaded along a guide wire that has been inserted in an artery in the groin and directed toward the valve. The deflated balloon is positioned in the valve, where it is inflated several times at high pressure. While the procedure can double the size of the opening, it will never expand the valve to its original diameter—about the size of a quarter for the aortic valve and the size of a half-dollar for the mitral valve.Benefits of the procedure
While it’s still not clear whether valvuloplasty is effective for all narrowed valves, physicians are high on the fact that it uses the patient’s own tissue to minimize the formation of blood clots, sparing patients a lifetime on anticoagulant medication. And patients, of course, welcome the chance to avoid open-heart surgery as well as the promise of a quicker, less painful recuperation.