Aortic Stenosis & Transcatheter Aortic Valve Replacement Versus Surgical Aortic Valve Replacement
August 7, 2015A healthy heart beats roughly 100,000 times a day and pumps about five quarts of blood each minute, or 75 gallons every hour. Its job is to supply the body with oxygen rich blood. Blood is pumped through the heart’s four chambers with the help of four heart valves. These heart valves open when the heart pumps to allow blood to flow forward and then close quickly between heartbeats to make sure blood does not flow backwards. Any disruption in this normal flow will make it difficult for the heart to effectively pump the blood where it needs to go.
As we get older, one of the more common problems that can disrupt this normal flow of blood is called aortic stenosis. Aortic stenosis occurs when the aortic valve, which directs blood from the left ventricle into the aorta (the major blood vessel that leads from the heart out to the rest of the body) doesn’t open properly, usually due to a buildup of scar tissue and calcium deposits. Other causes can include radiation therapy, medications, high cholesterol and a history of rheumatic fever. When the aortic valve doesn’t open properly, the heart is forced to work harder to pump the blood throughout your body. Over time, the heart muscle weakens which can affect your overall health and keeps you from participating in normal daily activities. If left untreated, severe aortic stenosis can become a very serious, life threatening conditioning leading to heart failure and increased risk for death. Signs and symptoms of severe aortic stenosis can include chest pain or tightness, dizziness, fatigue, feeling faint or fainting with activity, shortness of breath, heart palpitations and a heart murmur.
Traditionally, aortic valve replacement surgery has been the gold standard treatment for severe symptomatic aortic stenosis. This involves a surgical approach where usually the sternum (breast bone) is split down the middle and the chest is opened with retractors to provide the surgeon the necessary access to the heart and chest cavity in order to replace the aortic valve. The valve can be replaced with either a bovine (cow) or porcine (pig) valve or with a mechanical valve. This surgery is typically performed under general anesthesia and the damaged valve is removed and a new valve is sewn into the space where your own valve used to be. The surgery is performed while the function of your heart is taken over by a heart-lung or cardiopulmonary bypass machine and the patient is also placed on a ventilator while the surgery is being performed. It is considered an invasive procedure requiring increased recovery time. A typical hospital stay can be anywhere from 5-10 days and in some people may be longer if they require transfer to a rehabilitation facility before going home. An average recovery period is 6-8 weeks and includes sternal precautions (special precautions related to the breast bone having been split that allow it to heal properly – these include avoiding certain arm positions or movements and not lifting anything greater than 5-10 pounds).
Within the past several years, a newer and less invasive technique for replacing the aortic valve has been developed for older individuals who may have other diseases or conditions that put them at high risk for undergoing the traditional surgical aortic valve replacement. These patients may have previously been declined as candidates or not referred for the surgery at all. Transcatheter aortic valve replacement or insertion (TAVR/TAVI) involves the new replacement valve being inserted into the heart using a catheter to deliver it, rather than the traditional surgical approach for gaining access to the heart. The end of the catheter holds a small mesh framework (similar to a coronary stent) that has the new tissue valve inside. The catheter is guided from outside the body through the skin and then specified arteries, using specialized imaging equipment, and then is positioned within the diseased aortic valve. The new valve is then balloon expanded within the diseased valve and displaces the diseased leaflets, allowing the new valve to take over and function. The catheter is then removed. The primary methods of insertion are transfemoral (through the femoral artery and iliac artery) and transapical (through a tiny incision in the apex of the heart). Newer insertion routes also exist (subclavian/axillary artery and transaortic insertion) but are not as commonly used yet. This procedure is typically performed under local or general anesthesia.
This newer method of aortic valve replacement is considered much less invasive which is why it is a more preferable option for those patients who were not previously considered candidates for the traditional surgical approach. The typical hospital stay for TAVR/TAVI is between 3-5 days but again, as with the surgical approach, may be longer if transfer to a rehabilitation facility is required prior to returning home. This may often be the case, as the patients who are candidates for this type of aortic valve replacement procedure are more debilitated to begin with and are more prone to the effects of deconditioning. They may need therapy to improve their balance, strength and endurance, along with medical and nursing care to continue to adjust medications. An average recovery period is 1-2 weeks and there are no sternal precautions to adhere to. In addition, outpatient cardiac rehabilitation programs are effective to help patients continue to recover their function and independence.
As with any surgical procedure, there are certain potential risks and complications that may occur with either of these types of valve replacement surgery. It is important that patients discuss these with their physician in order to make an educated and informed decision regarding the risks versus benefits of either chosen technique for their aortic valve replacement.
-Michelle Caravano, PT
Supervisor, Cardiac Rehabilitation Service
