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The aorta is the main vessel that carries oxygenated blood to the whole body. Blood is oxygenated in the lungs, reaches the left ventricle, and the left ventricle pumps this oxygenated blood to the entire body through the aorta. The aorta contains a semilunar valve composed of three leaflets, which opens during left ventricular systole and closes during left ventricular diastole.

When a stenosis develops on the aortic valve, forward stroke volume from the left ventricle decreases and the afterload on the heart increases. Left ventricular myocardial mass increases in response to this rise in afterload and, in time, as the left ventricle becomes unable to cope with the excessively increased afterload, severe left ventricular failure, syncope and sudden death may develop.

In young adults, the common causes of aortic stenosis are degeneration of a congenitally bicuspid aortic valve (a congenital defect in which the valve has two leaflets instead of three), rheumatic heart disease and, very rarely, infective endocarditis. In the elderly, the most important cause of aortic stenosis is calcific degenerative aortic valve disease, characterized by the advanced degeneration and calcification triggered by aging.

Aortic valve stenosis is in fact a disease of older patients. It is seen in 2% of individuals over 65 years of age, in 3% of those over 75 and in 4% of those over 85, and it is the most common native valve disease in the elderly. Once age-related degeneration, arterial stiffening and calcification begin to involve the aortic valve, the development of stenosis is frequently unavoidable.

The classical signs and symptoms of aortic valve stenosis are angina, syncope, dyspnea due to heart failure, and sudden death. In untreated patients, mortality rates are 38%, 68% and 82% at 1, 5 and 10 years, respectively. When angina accompanies aortic stenosis, 50% of these patients die within 5 years; when syncope is present, 50% die within 3 years; and once a symptom of heart failure has developed, 50% die within 2 years. Symptomatic severe aortic valve stenosis is therefore a fatal disease that requires urgent treatment.

Medical therapy in aortic valve stenosis only reduces the severity of the signs and symptoms; it does not prolong survival. Medical treatment cannot restore a calcified, degenerated aortic valve.

In the past, the only treatment for aortic valve stenosis was the implantation of a new mechanical or bioprosthetic valve through open surgery. Today, in high-risk patients who cannot undergo open surgery, we are able to perform a catheter-based (closed) procedure termed transcatheter aortic valve implantation (TAVI).

Who Are the Candidates for the TAVI Procedure?

TAVI is the catheter-based implantation of a new heart valve, without the need for open heart surgery, in patients with severe aortic valve stenosis.

TAVI may be performed in particular in patients who:

• have severe aortic valve stenosis;
• have symptoms of dyspnea, chest pain or syncope;
• have been evaluated by the Heart Team;
• are at high or intermediate surgical risk, or are appropriately selected low-risk patients.

The closed method is not suitable for every patient with severe aortic valve stenosis; patient selection is based on surgical risk. If the patient is able to undergo open surgery, if there are no risk factors that would increase the likelihood of an adverse surgical outcome and if the risk score is low, open surgery remains the preferred option, even at an advanced age.

However, aortic valve stenosis is principally a native valve disease of older patients, and these patients frequently have comorbid conditions that both adversely affect the results of open surgery and reduce the likelihood of weaning from the heart-lung pump and of survival after the operation. Such comorbidities include chronic obstructive pulmonary disease, severe cardiovascular disease, severe heart failure, hepatic cirrhosis, diabetes mellitus and renal failure. In most elderly patients, one or more of these conditions accompanies the valve disease.

Several important risk scores are currently available, developed according to the presence or absence of such comorbid diseases and conditions in patients with aortic valve stenosis. The greater the number of these risk factors, the higher the risk score, and the higher the mortality if such a patient is taken to open surgery.

A patient with a diagnosis of aortic valve stenosis should therefore ideally be assessed jointly by a Heart Team comprising an interventional cardiologist, a cardiologist, a cardiac anesthesiologist and a cardiovascular surgeon, and the treatment strategy should be determined by the consensus of this multidisciplinary team. If the risk score is high and there are significant comorbid conditions that preclude open surgery, TAVI should be considered.

Today, for many patients, TAVI is no longer merely an alternative to open heart surgery; it has become one of the directly preferred treatment options.

How Can We Perform the Closed Method (TAVI)?

The femoral (groin) arteries provide the principal access route to the aorta and the left ventricle. In our catheterization laboratory, the femoral artery is punctured with a fine needle and a sheath is placed in the vessel.

Catheters are advanced through this sheath into the aorta, and the aortic valve is then crossed with a dedicated guidewire. Once the stenotic valve has been crossed, a stiff guidewire is positioned in the left ventricle.

A balloon is advanced over the stiff guidewire to the aortic valve and inflated. After this balloon aortic valvuloplasty, the delivery catheter carrying the crimped new aortic valve is advanced to the aorta. Balloon-expandable valves are deployed by inflating the balloon, whereas self-expanding valves are released by unsheathing the delivery system; implantation is performed under fluoroscopic guidance.

The new valve begins to function immediately and blood flow becomes close to normal. In most cases the procedure can be performed without general anesthesia.

The femoral artery is not always suitable for the implantation of a transcatheter aortic valve. In such cases, transapical, transaortic or transsubclavian access can be used.

What Is the Duration of the Recovery Period After the Closed TAVI Method?

After the TAVI procedure, the patient is monitored in the coronary care unit for one day. If there is no complication, discharge takes place within three or four days. Return to normal daily life is generally achieved within one or two weeks of the procedure. Patients must, however, take their prescribed medication regularly, and follow-up visits must be performed at one, three and six months after the procedure.

What Are the Advantages of TAVI Compared with Open Surgery?

For a high-risk patient, this method offers important advantages over open surgery:

• It is performed without opening the chest, which also offers a cosmetic advantage.
• Hospital stay is shorter and recovery is faster than after open heart surgery.
• Complications are rare, and the complications specific to open heart surgery, such as bleeding or trauma to the great vessels and the surrounding structures, are not encountered.
• In open heart surgery the heart is stopped and extracorporeal circulation with a heart-lung pump is used. TAVI is performed without extracorporeal circulation and without a heart-lung pump, so cardiac performance is not impaired by bypass.
• It can be performed safely in patients of advanced age and in those with comorbid conditions.
• It provides a marked improvement in quality of life and in daily activities.

The treatment decision is made after a detailed evaluation by the Heart Team, which comprises specialists in cardiology, cardiovascular surgery and cardiac imaging.

What Are the Complications of the Closed Method (TAVI Procedure)?

Complications that may occur during the TAVI procedure include vascular complications such as femoral artery injury and hematoma, neurological complications such as stroke and transient ischemic attack, paravalvular leak, coronary complications, and conduction disturbances that may necessitate permanent pacemaker implantation. These complications are nevertheless rare compared with open surgery.