Transcatheter aortic valve implantation (TAVI)

[Pyankov Vasily]

Technology and techniques of TAVI

Currently two devices have been commercialised:

The Edwards SAPIEN valve consists of three bovine pericardial leaflets mounted within a tubular stainless steel stent. It exists in 23 and 26mm sizes, and a 29 mm size is nearing commercialisation. It is available for both ante- and retro-grade implantation. The valve is deployed by balloon expansion under rapid pacing of the heart.
The CoreValve ReValving system consists of three porcine pericardial leaflets mounted in a selfexpanding nitinol stent. It exists in 26 and 29 mm sizes and is available for retrograde implantation.
TAVI is performed under fluoroscopic and echocardiographic guidance, ideally in a dedicated hybrid operating room offering both catheter-based and surgical facilities. A multidisciplinary approach involving cardiac surgeons, cardiologists and anesthesiologists is crucial for the success of the procedure.

Choice of approach
The retrograde transfemoral/subclavian (TF) approach is performed using the Seldinger technique through the common femoral or subclavian/axillary artery either prepared surgically or approached percutaneously.
The antegrade transapical (TA) approach concerns only the balloon-expandable prosthesis. It is performed through a left antero-lateral minithoracotomy under general anesthesia.
ach approach has its advantages. Although there are no direct comparative studies for the two approaches, we described outcomes according to an inclusion strategy that favours the TF approach, leaving the TA approach for patients refused all other options. The mean predicted mortality rate was 28% by the EuroSCORE and 16% by the STS score for the study population, but co-morbidities were more frequent in TA patients. Successful implantation was 85.7% and 100% in the TF and TA group respectively, with satisfactory gradients and valve orifice area in all surviving patients. Greater procedural safety and success with the TA approach may be explained by the fact that it is more direct, allowing surgical control of the site of puncture and introduction of the necessary instruments.

The most frequent complications were major vascular observed in the TF group. However, this is expected to decrease with reduction of the diameters of the introduction systems. Stroke was observed in the TF group (6%) only. The absence of stroke in the TA group is probably related to the antegrade positioning and manipulation of the delivery system and valve, a consistent advantage of this approach. On the other hand in-hospital mortality rate was 8% in the TF and 27% in the TA group. This correlated with the higher risk and greater prevalence of major co-morbidities in TA patients, which negatively influenced survival. The results in each approach were thus strongly influenced by the selection strategy. The respective places of both approaches need to be clarified for each approach by a randomised study.

http://www.escardio.org/congresses/esc- ... rgast.aspx