Protez Kapak Deliği veya Yırtığı

In young and middle-aged patients, rheumatic fever and congenital disorders, and in the elderly, age-related degeneration, cause damage to the heart valves. For this reason many patients undergo open surgical implantation of a bioprosthetic or mechanical prosthetic heart valve for valve regurgitation or valve stenosis. In these prostheses, which are most often implanted in the aortic or mitral position, a defect or tear may develop after open surgery along the suture line by which the sewing ring of the prosthesis is anchored to the tissue, as a result of infection, calcification, suture dehiscence or other mechanisms. Such defects or tears are termed paravalvular leak. When this occurs, most patients develop recurrent heart failure, or anemia and jaundice resulting from hemolysis of red blood cells at the site of the tear, and the patient is referred for a second open operation. However, the likelihood that a defect or tear will develop again after a repeat operation of the same type is even higher. Reopening the chest a second time carries a major risk for the patient and is associated with a number of complications. Closing these defects with dedicated devices, without open surgery, therefore offers considerable benefit to both the patient and the physician.

Paravalvular Leak

Prosthetic valve defects, termed paravalvular leaks, are an unwanted complication occurring in 8–18% of patients after surgery for valvular heart disease. They commonly present with recurrent dyspnea, signs and symptoms of heart failure, and advanced anemia or jaundice resulting from hemolysis of red blood cells at the site of the tear. Paravalvular leaks are classified principally as mitral and aortic paravalvular leaks.

Mitral Paravalvular Leaks

Mitral paravalvular leaks arise after implantation of a mitral bioprosthesis or mechanical prosthesis and take the form of round, crescentic or oval defects, most often located at the posteromedial aspect of the prosthetic mitral valve. A leak in this region gives rise predominantly to the signs and symptoms of mitral regurgitation. The mitral valve normally conducts oxygenated blood from the left atrium to the left ventricle; when a defect develops alongside the prosthesis, blood regurgitates from the left ventricle into the left atrium during left ventricular contraction and ejection, and the jet flow through the defect or tear fragments the red blood cells. This may lead to severe anemia with fatigue and pallor, or to jaundice with yellowing of the skin and darkening of the urine.

Aortic Paravalvular Leaks

Aortic paravalvular leaks arise after implantation of an aortic bioprosthesis or mechanical prosthetic valve and are most often located at the lateral aspect of the prosthetic aortic valve, frequently as long oval, tunnel-like or cylindrical defects. A leak caused by a defect or tear in this region gives rise to the signs and symptoms of aortic regurgitation, or to advanced anemia and jaundice resulting from hemolysis of red blood cells at the site of the tear.

How Is the Diagnosis Made?

A prosthetic valve defect or tear can today be diagnosed with modern high-resolution ultrasound imaging, known as echocardiography. Transthoracic echocardiography, performed simply by placing an ultrasound probe on the anterior chest wall, raises the suspicion of a leak; the definitive diagnosis is then established by transesophageal echocardiography (TEE), in which the probe is swallowed and positioned in the esophagus. Once the color Doppler jet has been demonstrated on two-dimensional (2D) TEE, three-dimensional (3D) echocardiography readily establishes the location, number, shape and size of the defect or tear and whether it is amenable to device closure. 3D TEE is currently accepted as the gold standard for establishing the diagnosis and determining the treatment strategy in prosthetic valve defects and tears. In our clinic, 3D TEE is performed in every patient in whom a prosthetic valve defect or tear is suspected.

Who Is Eligible for the Transcatheter Method and How Is It Performed?

In the past, the only treatment for a paravalvular leak was open surgery, with either resuturing of the site or implantation of a new valve. Today these tears or defects can be closed in the angiography laboratory by a transcatheter approach with dedicated devices, without open surgery. Transcatheter closure of paravalvular leaks arising around a prosthetic heart valve is a treatment that Prof. Dr. Teoman Kılıç pioneered in Türkiye, establishing Kocaeli University as a reference center for the procedure. It is a minimally invasive treatment performed through catheters, without open heart surgery.

The procedure is generally performed in the angiography laboratory under echocardiographic and fluoroscopic guidance. Access is obtained with fine catheters through the femoral vessels of the groin or, where necessary, through alternative vascular routes. The leak is crossed with dedicated guidewires, and a closure device appropriate to the shape and size of the leak is selected. The device is positioned at the site of the leak and the opening is closed. During the procedure it is confirmed that the device does not interfere with normal function of the prosthesis and that the leak has been adequately sealed. Most patients are able to return to their daily lives within a few days.

Mitral paravalvular leak closure. The mitral prosthesis lies between the left atrium and the left ventricle. A defect alongside the mitral prosthesis can be crossed by either of two routes: the antegrade approach or the retrograde approach.

Antegrade approach. The veins of the groin return deoxygenated blood from the legs to the right atrium. In our catheterization laboratory the femoral vein is punctured with a fine needle and a sheath is placed, through which small catheters are advanced into the right atrium. A transseptal puncture is then made through the atrial septum, the partition between the right and left atria, giving access from the right to the left atrium. Once the catheter or guidewire is in the left atrium, a dedicated steerable catheter is advanced into the chamber; using this catheter the defect is localized, and small catheters together with a dedicated guidewire are passed through the steerable catheter to cross the paravalvular leak. After the leak has been crossed, the catheter is advanced into the left ventricle and a snare is introduced from the contralateral femoral artery; the guidewire is then captured in the left ventricle and an arteriovenous wire loop is created. In our clinic, these defects can also be closed by the antegrade approach without an arteriovenous wire loop. Once the wire loop has been established, the delivery system of the closure device is advanced from the femoral vein. When the delivery system reaches the left ventricle, the distal part of the device is deployed, and the system and the device are withdrawn to the defect; the waist segment of the device is deployed within the defect and the remaining part in the left atrium, closing the defect. After the procedure, endothelialization of the device occurs within 6 months to 1 year.

Retrograde approach. The groin arteries are 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, through which small catheters are advanced into the left ventricle. The paravalvular leak is then crossed with a dedicated guidewire. After crossing the leak many centers create an arteriovenous wire loop; in our clinic, however, these defects are closed without creating such a loop. We believe that this approach reduces procedure time, radiation dose, cost and complications, and we have published our method in the Texas Heart Journal. Once the leak has been crossed, the delivery system of the closure device is advanced from the femoral artery. When the delivery system reaches the left atrium, the distal part of the device is deployed, and the system and the device are withdrawn to the defect; the waist segment of the device is deployed within the defect and the remaining part in the left ventricle, closing the defect. After the procedure, endothelialization of the device occurs within 6 months to 1 year.

Aortic paravalvular leak closure. The aortic prosthesis lies between the aorta and the left ventricle. A paravalvular leak alongside an aortic prosthesis is generally crossed through the femoral arteries of the groin. In our catheterization laboratory the femoral artery is punctured with a fine needle and a sheath is placed, through which small catheters are advanced into the aorta. The paravalvular leak is then crossed with a dedicated guidewire. Once the leak has been crossed, the delivery system of the closure device is advanced from the femoral artery. When the delivery system reaches the left ventricle, the distal part of the device is deployed, and the system and the device are withdrawn to the defect; the waist segment of the device is deployed within the defect and the remaining part in the aorta, closing the defect. After the procedure, endothelialization of the device occurs within 6 months to 1 year.

Transcatheter paravalvular leak closure is preferred in particular in patients who:

• have a severe paravalvular leak;
• have developed dyspnea or heart failure;
• require frequent blood transfusion because of hemolytic anemia;
• are at high surgical risk for a repeat operation;
• are considered suitable by the heart team.

What Are the Advantages of the Method?

• It can be performed without the need for open heart surgery.
• It offers a safe alternative in high-risk patients.
• It can provide marked improvement in symptoms.
• The hospital stay is shorter.
• It helps avoid the risks of a repeat surgical intervention.

Are There Complications of the Transcatheter Method or Side Effects of the Closure Devices?

Compared with open heart surgery, the complications of this treatment modality are very rare. The complications associated with open heart surgery, such as bleeding or trauma to the great vessels and adjacent structures, are not commonly encountered. The cosmetic advantage is also considerable, since the chest is not opened.

Most closure devices are manufactured from nitinol, a shape-memory alloy. No side effect has been reported other than nickel allergy. However, if these procedures are performed by inexperienced operators, the device may embolize to cardiac structures as a consequence of inadequate measurement, incorrect device selection or similar errors; dedicated snares are nevertheless available with which such a device can be retrieved from the body. Other very rare complications, such as bleeding, air embolism, pericardial effusion or tamponade, may also occur. These nonetheless remain very rare complications compared with open heart surgery.

In a small proportion of patients, signs of hemolysis may recur or worsen after the leak has been closed with a device; close follow-up in the early period after the procedure is therefore important.