Biological aortic valve prothesis with stent
Left: SAPIEN XT™, Edwards make
Right: CoreValve™, Medtronic make
Catheter-based aortic valve replacement
When conventional cardiac valve surgery is out of the question
Aortic valve stenosis is the most common type of valvular heart disease in industrialised countries. With rising life expectancy this disease predominantly afflicts older people. The surgical replacement of the aortic valve is the standard treatment leading to very good clinical results. In older patients with severe concomitant diseases, however, conventional cardiac valve surgery may be fraught with too high a risk. For this reason around 30 - 60% of these high-risk patients are not referred for surgical therapy by their family doctor or cardiologist. Hence, the severe cardiac valve disease remains untreated.
The catheter-assisted aortic valve replacement avoids excessive surgery trauma and is generally performed without heart-lung machine. Thus, for the first time ever, an effective and gentle therapy option becomes available to those high-risk patients.
Gentle cardiac valve replacement by means of advanced catheter technique
The catheter-assisted aortic valve replacement combines a balloon dilatation of the stenotic heart valve with the implantation of a biological aortic valve prosthesis. The great advantage of this surgical technique is that it is not necessary to open the patient’s thorax as the new aortic valve is inserted through the femoral artery (transfemoral) or through a small incision between the ribs (transapical).
Following a balloon dilatation of the diseased native heart valve, the aortic valve prosthesis is crimped onto the balloon catheter and an implantation device is used to advance it up to the native valve. Two markings on the balloon of the catheter serve to visualize the new valve during its implantation and to finally discriminate the position of the biological aortic valve prosthesis. The prosthetic valve consists of a fine stainless steel mesh frame (the stent) holding a tissue valve with three leaflets.
Once the catheter has reached the target location, the biological aortic valve prosthesis is positioned: The surgeon anchors it in the annulus of the diseased native valve. By injecting a liquid into the balloon the new valve is expanded and the diseased aortic valve simultaneously squeezed outward. The prosthetic valve is immediately functional and starts its valvular activity as soon as the balloon catheter is removed.
Transfemoral approach (catheter deployment through the groin artery)
Access is performed through a small incision in the groin, where the catheter system is introduced into the inguinal artery and advanced towards the heart. Before positioning the prosthetic valve the stenotic native aortic valve is dilated by means of a balloon. The implantation procedure is performed under X-ray monitoring. When the catheter has reached the correct location, the valve is expanded and its proper seating and functioning is checked by echocardiography and X-ray examination. Upon completion of the surgical intervention the inguinal artery is closed and the dermal layers involved are sutured. The application of the transfemoral technique requires favourable anatomical conditions in the inguinal and pelvic arteries. Therefore, prior to the surgical intervention it is necessary, among other examinations, to perform an iliofemoral angiography by means of CT/MRT.
To start an animation representation of the procedure, please click on the lower screen.
Animation representation: Edwards
Transapical approach (catheter deployment through the cardiac apex)
Here, the heart is accessed through a small incision under the left nipple to reach the apex of the heart. This access is used to insert the catheter and implant the cardiac valve prosthesis. Under X-ray monitoring the left apex is punctured and a soft guide wire introduced into the heart. In the transapical approach, too, the diseased stenotic aortic valve is first dilated. After again having checked the correct position of the new valve by X-ray examination, the new prosthetic valve is anchored in the aortic annulus. As in the transfemoral approach, the proper seating and functioning of the prosthetic valve is here, too, checked by echocardiography and X-ray examination.
To start an animation representation of the procedure, please click on the lower screen.
Animation representation: Edwards
Safety owing to an interdisciplinary team of experts
As early as in 2008, the Schüchtermann-Klinik started to apply the catheter-assisted aortic valve replacement technique. Meanwhile more than 150 high-risk patients have thus successfully been treated. Which makes the Schüchtermann-Klinik nation¬wide one of the cardiac centres with the largest experience in applying this new technique.
The interventions are performed in a hybrid operating theatre by a specialised team of intervention cardiologists, heart surgeons and anaesthetists. The patient is usually given general anaesthesia. In individual cases, however, a quasi-anaesthetic dormancy will do. For safety reasons every surgical intervention is performed having the heart-lung machine in readiness; the intervention takes about one hour.
To prevent the formation of blood clots on the biological heart valve, after catheter-assisted aortic valve replacement the patients must take a special anticoagulant (Clopidogrel) for three months and thereafter acetylsalicylic acid for the rest of their lives.
Use of the new technique limited to high-risk patients
Meanwhile, in Germany several thousand interventions of this type have been performed. According to the current state of relevant studies and to our experience it is a suitable new technique for high-risk patients. This assessment is based both on the good results shortly after the intervention and on a considerably improved clinical picture in the course of the following two years, when compared with patients being treated solely with drugs.
Applying this technique in patients who are at low risk when undergoing conventional cardiac valve surgery, however, is not reasonable considering the insufficient experience in the long term.
For information on conventional heart valve surgery, click here.
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