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

Prof. Grünenfelder (Cardiac Surgery) and Prof. Corti (Interventional Cardiology) explain the 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; minimally invasive access is via a small lateral opening of the chest or a partial transection 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 then replaced with 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

For elderly, chronically ill patients and weakened patients with multiple illnesses, 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), known as TAVI for short, is now also increasingly being performed on lower-risk patients due to 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, all patients undergo computed tomography of the aortic valve and especially of the vessels – from the aorta to the groin vessels. These images are then used to create a 3D reconstruction of the valve and the vascular system as well as their spatial arrangement in the body (Fig. 3). The size of the vessels and the aortic valve are also measured in order to select the right valve for the patient in advance (Fig. 4). Based on this 3D representation and the measurements, the most suitable access route to the aortic valve is then determined, paying attention to the size, severe calcifications and a tortuous course of the vessels.

Positioning of the aortic valve

The valve can be inserted into the diseased Aortic valve using a catheter via four access routes: via the groin (transfemoral) in 80 to 90 % of cases 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). 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 body’s own aortic valve ring (Fig. 1). The catheter is then removed again and the access route is closed. In contrast to open surgery, the aortic valve is not removed, but only pressed against the heart wall by the TAVI valve (Fig. 2). A heart-lung machine is not necessary for this intervention.

Catheter-based TAVI or minimally invasive aortic valve surgery?

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

In order to determine the optimal procedure for a patient with aortic valve disease, both therapeutic options should therefore be discussed impartially at an interdisciplinary conference of cardiac surgeons and interventional cardiologists.

As TAVI is an expensive procedure that currently only brings proven benefits to certain patients, it is important that an honest weighing up of interests takes place when selecting therapeutic procedures. As a result, TAVI should not only be chosen because the procedure is less invasive, but also because it will benefit the patient in the long term.

TAVI is indicated for so-called high-risk patients who are either over 80 years old and have additional risk factors such as renal insufficiency or who have already undergone heart surgery. Patients with a medium surgical risk can be recommended either TAVI or open surgery. On the other hand, conventional surgery should still be considered the standard for a low-risk patient, such as a patient under 70 years of age who is otherwise healthy.

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