Calcified aortic valves must be replaced

It is usually triggered by calcification. If left untreated, there is a risk of heart failure, which is why the aortic valve is replaced by a mechanical or biological one in the event of complaints.

“The aortic valve is the gateway between the left ventricle and the main artery. The pocket flap acts as a valve to direct the blood from the ventricle into the aorta and thus into the body circulation and to prevent it from flowing back into the heart afterwards ”, explains Prim. Priv.-Doz. Dr. Clemens Steinwender, Head of the Clinic for Cardiology and Internal Intensive Care Medicine at the Kepler University Hospital in Linz. But if this gate in the heart is narrowed, it has to apply more force to pump the blood into the body. In the long run, the heart muscle thickens (hypertrophy), becomes less and less flexible and thus weaker. His pumping performance decreases and heart failure sets in. This means that the body can no longer be adequately supplied with oxygen-rich blood.

The first signs are an insufficient supply of the brain, which can lead to dizziness or fainting. But also blood pressure fluctuations and low blood pressure, low resilience with rapid fatigue during exercise such as climbing stairs or during sport are the first symptoms. As the narrowing progresses, the symptoms increase, shortness of breath and pressure on the chest (angina pectoris pain) appear. With severe narrowing (stenosis) the symptoms are also present at rest.

Calcification or narrowing can go unnoticed for a long time, especially in people who do not move very much, and are only detected when a heart failure is diagnosed.

Deposits and wear

The most common cause of stenosis is wear and tear in old age. In this case, one speaks of calcification as in arteriosclerosis. In those over 75 years of age, three to five percent of the population have high-grade aortic valve stenosis. Elevated blood lipids and high blood pressure can be risks for calcification. Lime and collagen are deposited in the valve. Rheumatic fever, which is rare today, can also cause aortic valve stenosis. “A congenital constriction is less common and usually leads to wear and tear 20 years earlier than with the acquired constriction. The reason is usually a bicuspid aortic valve, which means that it only has two pockets instead of three and is therefore prone to stenosis early, ”says Steinwender.

Valve insufficiency can also be combined with the calcification and narrowing. The valve is then leaky, allowing blood to flow back from the aorta into the left ventricle. This leads to a stretching (dilation) of the left ventricle and also to a thickening of the heart wall. Other reasons for a leaky aortic valve can be a bacterial inflammation of the inner lining of the heart in the area of ​​the valve or a congenital tissue weakness of the aorta. The symptoms are similar to those of stenosis. The backwater can also cause heart failure and water in the lungs with difficulty breathing.

Different stages of narrowing

“As soon as symptoms appear and the quality of life suffers, or if certain criteria are met during the ultrasound examination that indicate a high degree of tightness or leakage, you have to think about replacing the heart valve,” says the cardiologist. In addition to the ultrasound, x-rays and listening with a stethoscope are used to make the diagnosis. Sometimes a stress test on the bicycle ergometer, a computed tomography or a cardiac catheter examination is necessary for clarification. The ultrasound can be used to assess the speed of blood flow at the constriction, the amount of blood that is still pumped out and also the area of ​​the valve opening. Typically, the valve opening in adults is three to four square centimeters. Depending on the opening, a distinction is made between three stages of the stenosis:

• Light: 1.5 to two cm²
• Moderate: one to 1.5 cm²
• High: less than one cm²

Implantation using a catheter

In order to restore performance and quality of life, the valve must be replaced in the event of a moderate to severe valve defect. Cardiologists, heart surgeons and anesthesiologists decide on an interdisciplinary basis about the best possible method of implanting the new valve. Medicines try to treat cardiac insufficiency as a result of calcification until the valve is replaced.

Until 2007, only open heart surgery under general anesthesia and connection to the heart-lung machine to replace the valve was possible in Austria. This stressful method was often not reasonable for older people with comorbidities.

That changed 13 years ago with the start of catheter-supported implantation (TAVI – Transcatheter Aortic Valve Implantation) of the valve. In the meantime, more aortic valves are used with TAVI, the minimally invasive and less stressful method, than with open heart surgery. Above all, patients with a medium to high surgical risk and older age benefit from TAVI. “With TAVI, a catheter, with the biological valve attached to it folded, is usually pushed through the old aortic valve via the inguinal artery under local anesthesia and implanted there using a high-pressure balloon. The old valve is pushed to the side and into the vessel wall of the aorta without any problems, ”explains Steinwender.

Constantly improved technology and new generations of valves mean that TAVI is the first choice therapy for many patients. In studies, the five-year results are not inferior to those of open surgery. According to Steinwender, the latest and very thin catheters allow the TAVI to be implanted very gently.

“With TAVI, groin bleeding can occur and in a few cases it is necessary to insert a pacemaker after the minimally invasive procedure because the aortic valve is very close to the heart rhythm conduction system,” says the cardiologist. Biological valves from pigs or cattle / calves are used in older patients who receive minimally invasive care. After the TAVI, an individual decision is made as to how long a blood thinning is necessary.

Open surgery in young patients

“In younger patients with low risk and in whom mechanical, i.e. plastic, valves are used because they guarantee a very long service life, the valve is surgically inserted. The old flap is cut out and replaced with the new one. If additional operations on the heart are necessary, such as a bypass, surgery is also open. The same applies if the valve is infected, ”says the cardiologist. Plastic flaps cannot be used via TAVI. Surgical risks include bleeding, infections, stress from the heart-lung machine or pain from opening the chest. Most patients have to do a lifelong blood thinning after the operation.

Another surgical method is that of Ross and is mainly performed in the case of congenital aortic valve stenosis in children, but also in young adults. The aortic valve is replaced by the pulmonary valve, which in turn is replaced by a human donor valve. The advantages of this method are the long shelf life of the flaps and optimal functionality. Lifelong blood thinning can also be dispensed with. But the method is very laborious and requires a donor valve.

If left untreated, aortic valve defect can have serious consequences, such as a stroke, because small blood clots form on the calcified valve and can be carried into the brain with the bloodstream. In addition to cardiac insufficiency, there are cardiac arrhythmias which, in the worst case, can lead to ventricular fibrillation with cardiac death.

With the right and timely treatment, the prognosis is very good.

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Christine Radmayr
January 2021

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