TAVI catheter for aortic valve replacement

Aortic valve replacement: surgical orcatheter-based using TAVI

Once developed for high-risk patients, this method of aortic valve replacement is increasingly being used for lower-risk patients. Weighing up open surgery versus TAVI, a precise definition of the possible access routes and exact planning of the procedure serve to ensure the highest possible safety.

Prof. Dr. med. Jürg Grünenfelder - Specialist Cardiac and Thoracic Vascular Surgery - HerzKlinik Hirslanden

Prof. Grünenfelder (Cardiac Surgery) and Prof. Corti (Interventional Cardiology) explain TAVI intervention

Surgical aortic valve replacement is the treatment of choice for high-grade aortic valve stenosis. In open surgery, the sternum is cut along its longitudinal axis, thus opening the chest; the minimally invasive approach is performed through a small lateral opening of the chest or a partial cutting of the sternum in the upper third. In all three approaches, a heart-lung machine is used to operate on the calcified aortic valve. The defective valve is removed and subsequently replaced by a biological or mechanical valve prosthesis. The results of open or minimally invasive surgical aortic valve replacement are very well documented and today show a very low mortality rate of only 2 to 4% for all patients with aortic stenosis.¹ Symptoms such as chest pain and tightness, weakness, shortness of breath and even fainting on exertion usually disappear.

TAVI as an alternative for high-risk patients

Prof. Dr. med. Roberto Corti - Medical Director - Interventional Cardiology - HerzKlinik Hirslanden

For elderly, chronically ill patients and weakened patients with multiple diseases, such an operation was associated with too high a risk. In order to be able to treat these high-risk patients as well, a catheter-based method was developed as an alternative to open surgery, which is used by cardiologists. This catheter-based aortic valve replacement (transcatheter aortic valve implantation), or TAVI for short, is now increasingly being performed in lower-risk patients because of the good results and the gentle procedure.

3D planning of the valve intervention

In order to be able to perform a TAVI with the greatest possible safety, meticulous planning of the intervention is required. For this reason, a computer tomography of the aortic valve and especially of the vessels - from the aorta to the inguinal vessels - is performed in all patients. These images are then used to produce a 3D reconstruction of the valve and vasculature and their spatial arrangement in the body (Fig. 3). The size of the vessels and the aortic valve is also measured in order to select the appropriate valve for the patient in advance (Fig. 4). The most suitable access route to the aortic valve is then determined on the basis of this 3D representation and the measurements, paying attention to the size, severe calcifications and a tortuous course of the vessels.

Positioning of the aortic valve

The valve can be inserted by catheter into the diseased aortic valve via four access routes: via the groin (transfemoral) in 80 to 90 % and alternatively in 10 to 20 % of cases directly via the apex of the heart (transapical), via the subclavian artery (trans-subclavian) or directly via the ascending aorta (transaortic). Both the transapical and transaortic approaches require a small opening of the chest between the ribs. The alternative approaches are chosen if the inguinal vessels are either too small, too calcified or too tortuous.

Under X-ray control, the new valve is then placed precisely at the level of the endogenous aortic valve ring (Fig. 1). The catheter is then removed and the access route closed. In contrast to open surgery, the aortic valve is not removed but merely pressed against the heart wall by the TAVI valve (Fig. 2). A heart-lung machine is not necessary for this intervention.

Catherter-based TAVI or minimally invasive aortic valve surgery?

The results achieved with a TAVI aortic valve replacement can also be described as good in view of the symptoms. The risk of death from the operation within 30 days is 3 to 5% worldwide.2 How long this valve will remain functional is still unclear, as long-term results are lacking. However, there is no evidence to date that it should last less than conventional bioprostheses. However, a higher rate of pacemaker implantation must be expected with TAVI compared to open surgery.

Therefore, to determine the optimal approach for a patient with aortic valve disease, both therapeutic options should be discussed impartially in an interdisciplinary conference of cardiac surgeons and interventional cardiologists.

Since TAVI is an expensive procedure that currently provides a proven benefit only to certain patients, it is important that there is an honest balancing of interests when selecting therapeutic procedures. This should result in TAVI being chosen not only because the procedure is gentler, but also because it will benefit the patient in the longer term.

TAVI is indicated in so-called high-risk patients who are either over 80 years old and have additional risk factors such as renal insufficiency or who have had previous heart surgery. Patients with an intermediate surgical risk may be recommended either TAVI or open surgery. On the other hand, in a low-risk patient, such as a patient under 70 years of age who is otherwise healthy, conventional surgery should continue to be considered the standard of care.

¹ Brown JM et al, Ann Thorac Surg 2009;137:82-90, Plass AR et al, Ann Thorac Surg. 2009 Dec;. 88 (6): 1851-6, Lamelas J et al, Ann Thorac Surg. 2011 Jan;91(1):79-84; ² Wenaweser P et al, EuroIntervention 2014.