Description of the aortic root anatomy in relation to transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI) has emerged as a less invasive treatment than surgical aortic valve replacement in patients with aortic stenosis. Understanding the anatomy of aortic valve complex may help in optimal positioning of prosthetic valve and circumvent complications that can arise during its implantation.

The anatomy of aortic root was studied in 30 formalin-fixed cadavers. Aortic root and left ventricular cavity was opened to measure the diameter at the base of aortic root and sinotubular junction (STJ); distance of coronary ostia from base of aortic root and STJ; height and width of aortic valve leaflets; length and thickness of membranous septum (MS).

The diameter of aorta at the base of aortic root and STJ was 22.4±2.1 mm and 21.8±2.4 mm, respectively. The height of aortic leaflets was smaller than the width. The right and left coronary ostia were 10.7±1.9 mm and 10.5±1.9 mm above the base of aortic root. Membranous septum was 4.7±1.23 mm (range 2.9-6.1 mm) long and formed part of the wall of aortic root in 40% (12/30) cases.

Low lying coronary ostia speculate the use of a small prosthesis size to avoid or reduce the degree of coronary compression. Length of MS may help in deciding the extent of devise penetration into left ventricular outflow tract to avoid conduction block. Membranous septum forming wall of aortic root increases the risk of aortic root rupture and iatrogenic membranous defect during TAVI.