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Aortic aneurysm: Handmade prosthesis saves lives

News

15. April 2020

The aorta distributes blood throughout the body. Tears in this blood vessel can be fatal. Zurich University Hospital offers a procedure for this emergency which is unique in Switzerland: Surgeons make a customized prosthesis directly in the operating theater.

The aorta is the main conduit through the human body. It is the largest and most important of all the arteries and transports blood from the heart to the various blood vessels. Tears in the aorta can be fatal.

Men aged between 65 and 75 are particularly at risk: Around 2 percent of them have a so-called aneurysm in the abdominal area, a bulge in the aorta that can eventually tear. “Patients who smoke or have high blood pressure are particularly at risk,” says Professor Alexander Zimmermann, Director of the Department of Vascular Surgery at Zurich University Hospital.

Since an aneurysm causes no symptoms but is potentially extremely dangerous, regular check-ups are recommended for high-risk patients. Family doctors can identify aneurysms on ultrasound images. “Afterwards, discussions should be held with a specialist to determine whether immediate action should be taken or whether the situation should be monitored for the time being,” says Zimmermann.

In the event of an emergency, the tear can now be repaired using a new, relatively gentle procedure which in Switzerland can only be performed at the USZ. This is an endovascular procedure, i.e. it takes place inside the blood vessels. A catheter (small tube) transports a compressed prosthesis to the site of the tear, where it expands and seals the aorta. Compared to open surgery on the thoracic or abdominal aorta, this catheter procedure has the advantage that only small incisions are required; this is not as hard on the patient and entails less risk.

Computer-aided with a steady hand

Nowadays, catheter surgery of this type is standard procedure in any operating theater. However, until recently it could not be performed on tears in the parts of the aorta located near the vessels that supply the organs. This is because numerous blood vessels branch off from this artery as it passes through the abdomen. The anatomy of this area varies from person to person, which is why standard prostheses cannot be used. For this new procedure, Alexander Zimmermann simply constructs a customized prosthesis himself. “Ordering it externally would take 4 to 6 weeks. If we make it ourselves, we only need one to one-and-a-half hours,” explains Prof. Zimmermann, who is one of only a few doctors skilled in this method.

The prosthesis is made directly in the operating theater while the anesthetists and nursing staff prepare for the surgery. A computer tomography scan (CT) of the patient and a simulation at the computer show the surgeons how the prosthesis should be modified for the best possible fit. “You need a great deal of finesse,” says Zimmermann.

The method is still new but the results so far have been extremely positive, says the expert. In principle, the procedure is only used in emergencies. Moreover, it is used almost exclusively in older patients, for whom open surgery would be too stressful. The patient’s anatomy may also make the procedure impossible, i.e. if the shape and location of the blood vessels mean that a catheter cannot be inserted.