Aortic valve stenosis: description
Aortic valve stenosis (aortic stenosis) is the heart valve defect that most often requires treatment. Looking at case numbers alone, mitral valve regurgitation is the most common valvular heart defect of all in Europe and North America. However, it does not need to be treated as often as aortic valve stenosis.
The aortic valve consists of three crescent-shaped pockets. It is located between the left ventricle and the aorta. There, it serves as a valve so that blood can only flow in one direction – namely into the large bloodstream – and does not flow back into the heart.
This “exit” from the heart is narrowed in aortic valve stenosis. Because of this resistance, the heart must exert more force to open the valve and continue pumping blood. As a result, the heart muscle visibly thickens (hypertrophy). Over time, it becomes less elastic and weaker, and the pumping capacity decreases. In the case of advanced aortic valve stenosis in particular, the muscle is no longer able to transport sufficient oxygen-rich blood into the systemic circulation.
Aortic valve stenosis: symptoms
At the beginning, those affected usually complain of dizziness and an occasional circulatory collapse leading to loss of consciousness (syncope). This is due to the lack of blood flow to the brain as a result of aortic stenosis. Especially in situations of physical stress (climbing stairs or even sports), the heart can hardly keep up: because of aortic valve stenosis, the heart can no longer pump enough blood out of the heart to meet the body’s increased demand for oxygen during physical activity.
To pump against aortic valve stenosis, the left ventricle needs more muscle power. Over time, it adapts by increasing in size (concentric left ventricular hypertrophy). The increase in heart muscle tissue also increases its need for oxygen. In addition, the thickened muscle constricts the coronary vessels that supply the heart with blood and oxygen, especially when the heart is strained. As a result, patients complain of tightness or chest pain (angina pectoris), even if the coronary arteries themselves are healthy.
Therefore, look out for the first signs of heart failure: performance decreases, you weaken quickly, and you experience shortness of breath under exertion. In addition, some symptoms start at night, such as coughing.
Aortic valve stenosis: causes and risk factors
Aortic valve stenosis can be acquired or congenital.
Acquired aortic valve stenosis
In most cases, aortic valve stenosis is acquired, most often due to wear and tear (calcification) processes in older age. This process is similar to that of atherosclerosis. Therefore, risk factors such as elevated blood lipids favor the development of aortic valve stenosis. Calcium and collagen are deposited in the valves. This visibly thickens and hardens. Initially referred to as aortic valve sclerosis, these processes eventually lead to narrowing of the valve, which is why doctors then refer to aortic valve stenosis.
Rheumatic fever (nowadays rare due to early consistent antibiotic treatment of a streptococcal infection) can also cause scarring and thus aortic valve stenosis due to autoimmune reactions: Scar tissue is less flexible than healthy tissue, which impedes blood outflow from the heart into the aorta.
Congenital aortic valve stenosis
Most often, the heart valve itself is affected by the narrowing (valvular aortic valve stenosis). It usually consists of only two leaflets (bicuspid aortic valve). If it is not already narrowed, bicuspid aortic valves stenose on average twenty years earlier than regular valves. If the area above the aortic valve (i.e., the beginning of the aorta) has narrowed, it is called supravalvular aortic stenosis. In subvalvular aortic valve stenosis, the tissue below the heart valve is narrowed.
Aortic valve stenosis: examinations and diagnosis
If aortic valve stenosis is suspected, the doctor first asks about the patient’s medical history and possible complaints (anamnesis), for example:
- How active are you? (Sometimes complaints of aortic valve stenosis do not show up only because the affected person hardly moves!)
- Do you feel increasingly fatigued in recent months?
- Do you tire quickly during physical exertion?
- Do you feel shortness of breath?
- Have you fainted recently?
- Do you have pain or a feeling of pressure in your chest?
The physician hears the aortic valve stenosis with the stethoscope best between the second and third rib directly to the right of the sternum.
In order to confirm the diagnosis of “aortic valve stenosis”, further diagnostic tests are usually performed:
X-ray
In the X-ray image of the chest, the physician can see any wall thickening of the left ventricle or dilatation of the aorta. A lateral X-ray can even show calcification of the aortic valve.
Electrocardiography (ECG)
As a rule, an ECG is also performed if aortic valve stenosis is suspected. The typical serrated pattern of the ECG shows the thickening of the wall of the left ventricle.
Echocardiography
Echocardiography is an ultrasound examination of the heart. It can be used to assess aortic valve stenosis and its extent very well. Among other things, the blood flow velocity at the constriction and the amount of blood that the heart is still pumping out are measured. The valve opening area can also be determined, i.e. how far the aortic valve still opens. The valve opening area (usually three to four square centimeters in adults) is an important diagnostic tool for determining the severity of aortic valve stenosis:
- Mild aortic valve stenosis: 1.5 to two square centimeters
- Severe aortic valve stenosis: smaller than one square centimeter
For echocardiography, examiners place the ultrasound probe on the chest (transthoracic, TTE) or guide it through the esophagus directly next to the heart (transesophageal, TEE). TEE is closer to the heart and therefore provides more accurate ultrasound images.
Stress tests
Sometimes doctors see aortic valve stenosis on ultrasound, but the patient has no symptoms. This is sometimes followed by examinations under stress, such as with a bicycle ergometer. This may reveal symptoms that require further treatment.
Cardiac catheter examination
During a cardiac catheter examination of the left heart, a thin plastic tube (catheter) is usually inserted into an artery at the wrist or in the groin and advanced via the aorta to the aortic valve. Doctors use this examination to detect coronary artery disease. This is especially important if heart valve replacement is planned due to aortic valve stenosis. Alternatively (and depending on the individual situation), doctors arrange for a computer tomography of the heart with contrast medium (cardio-CT).
Aortic valve stenosis: treatment
Moderate to high-grade aortic valve stenosis usually already causes symptoms. If patients with higher-grade aortic stenosis nevertheless have “no complaints,” it is usually because they are unconsciously taking care of themselves physically so that no complaints occur. If additional symptoms are present in such patients (such as a pathological stress test, etc.) and in symptomatic patients, surgical therapy is recommended.
Aortic valve stenosis: TAVI and surgery
Doctors use different procedures for aortic valve stenosis:
Aortic valve replacement is particularly common for acquired stenosis. For this, doctors either operate on the open heart or insert a new valve minimally invasively during a cardiac catheterization (TAVI = Transcatheter Aortic Valve Implantation). Open surgery is usually performed on younger patients with a low surgical risk. Doctors also advocate the operation in particular when additional procedures are necessary, such as a bypass.
If surgery cannot be performed, for example due to old age and concomitant diseases, doctors recommend TAVI. During a cardiac catheterization, they guide the new, still folded valve (usually a biological valve suspended from a metal mesh stent) on a catheter to the aortic valve. There, a balloon pushes the metal mesh apart, which eventually anchors the valve between the chamber and the aorta. To make room for the new valve, the aortic valve stenosis is previously widened using a small balloon (balloon dilatation).
Balloon dilatation alone (balloon valvuloplasty) is also used in children with congenital aortic valve stenosis. Valve replacement is problematic here because it cannot grow with the child. In acquired aortic valve stenosis, balloon dilatation has a high recurrence rate. Doctors therefore only resort to this method in emergencies to bridge the time until definitive therapy.
Aortic valve stenosis: Medications
Sports in aortic valve stenosis
There are no general recommendations for or against sports activities in aortic valve stenosis. The decisive factor is always the type and severity of the disease.
Patients find out whether sport is possible during their annual cardiological check-up. During this check-up, the attending physician examines the heart valve for possible damage and can make or update a recommendation for sporting activity.
Starting exercise with aortic valve stenosis
Before a patient with aortic valve stenosis begins to exercise, an exercise ECG is necessary.
Although aortic valve stenosis was long considered an exclusion criterion for an exercise ECG. This is still true for patients with symptomatic high-grade AS. However, especially in patients who are asymptomatic, an exercise ECG can be helpful in detecting possible limitations in exercise capacity.
The stress ECG takes place under strict medical supervision, as undesirable side effects can quickly occur.
If a drop in blood pressure or cardiac arrhythmia occurs on the ergometer, the exercise should be stopped immediately.
After the examination, the cardiologist can use the data to assess the intensity at which the patient can become physically active.
Suitable sport for aortic valve stenosis
The following overview shows which sports are possible for which severity of aortic valve stenosis:
Severity mild (no symptoms, normal age-appropriate pump function on cardiac echo, unremarkable exercise ECG): Recommendation on physical activity: all sports are possible; including competitive sports.
Severity medium (normal pump function, unremarkable exercise ECG): Physical activity recommendation: sports with low to moderate static and dynamic components: walking, level cycling, golf, bowling, yoga, table tennis, volleyball, fencing, softball, archery, horseback riding
Severity severe (impaired cardiac performance): Physical activity recommendation: no competitive sports; in individual cases for asymptomatic patients, walking, cycling on level ground, golf, bowling, yoga
Always follow the doctor’s recommendation for aortic valve stenosis. Before starting a new sport or changing your exercise plan, consult with your doctor.
Aortic valve stenosis: disease progression and prognosis
Aortic valve stenosis can also cause cardiac arrhythmias. If left untreated, these can lead to ventricular fibrillation and cardiac death. Ultimately, progressive aortic valve stenosis causes increasing heart failure, which is rapidly fatal without proper therapy.
However, with proper treatment of aortic valve stenosis, the prognosis is good.
