Surgical implications of variations in the anatomy of the aortic root.

Abstract

Introducing their recent experience with the technically demanding valvar-sparing surgery on the aortic root, Oishi et al. [1] emphasize that ‘the surgeon must have sound knowledge of the anatomy and function of the aortic valve’. Better had they stated that knowledge was required regarding the features of the aortic root, which extends from the virtual basal ring to the sinutubular junction [2], since the valve is but 1 component of this complex structure. Discussion of its components has been hampered over recent decades by virtue of the numerous terms used for description. As was shown by the questionnaire conducted a decade ago by the German surgeons [3], it still remains problematic to reach a consensus on these issues. The surgeons from Tokyo have focussed on the complications of inadvertent perforation of the right atrium, and damage to the tricuspid valve. They have shown that, in their hands, variations in the rotation of the root relative to the base of the left ventricle influenced these complications. Such variation has been highlighted as an important feature for those undertaking transcatheter replacement of the aortic valve [4], but thus far has received little attention amongst the surgical community. From their stance, they classified the observed rotation as seen by the imager from the apex of the ventricle and clarified how this is mirror-imaged when viewed by the surgeon. As is now increasingly the case, their findings in the operating room supplemented the changes previously diagnosed using computed tomographic interrogation. This technique is rapidly establishing itself as the new ‘gold standard’ for the visualization of cardiac anatomy. It has the inestimable advantage of showing the anatomy in the setting of the heart within the chest and revealing the subtleties without the need to distort the relationships relative to neighbouring structures. As the Tokyo surgeons emphasize, however, those using computed tomography show their images as seen from the ventricular apex, whereas the cardiac surgeon views the aortic root from the atrial aspect. As long as this difference is kept in mind, there will be no problem, but it is capable of creating confusion. Rotation of the root from its normal position was observed in around one-sixth of their patients, with most having counter-clockwise rotation as defined from the perspective of the imager. Counter-clockwise rotation meant that a greater proportion of the right coronary sinus was related to the wall of the right atrium. This resulted in increased difficulty in dissecting the sinus, with an increased incidence of right atrial perforation and damage to the tricuspid valve.