The Aortic Root: A Unique Component Of The Thoracic Aorta -- Implications For Surgical Management

ABSTRACT INTRODUCTION: Ascending thoracic aortic aneurysm (TAA) is a clinically silent disease with a natural course often culminating in aortic dissection or congestive heart failure from aortic valve regurgitation, without surgical correction. There are two primary operative techniques for corrective repair of ascending aortic aneurysms: aortic root-sparing (RS) procedures and aortic root replacement (RR) approaches. Root-sparing operations are well established and associated with a very low perioperative risk profile compared to other techniques. Furthermore, the aortic root is an embryologically dissimilar tissue from the rest of the aorta and may have inherently different tissue properties. However, many surgeons recoil from the idea of leaving the aortic root in situ, as it may serve as a site of subsequent dilation requiring redo surgical correction. Thus, in this study we assess the rate of postoperative aortic root dilation in patients following RS procedures to quantify the true rate and risk of late aortic root aneurysmal dilation. METHODS: We employed a retrospective chart review of 113 patients treated at the Yale Aortic Institute between 2004-2011 and operated on with a supracoronary root-sparing (RS) surgical approach. All patients with root replacement operations, syndromic or genetic disorders, connective tissue disorders, aortic dissections, intramural hematomas or redo cardiac operations were excluded. The primary endpoint was to determine the natural aortic root growth rate in patients postoperatively following RS operations. Further subanalyses of the influence of concomitant aortic valve replacement (AVR) and effects of alular morphology on the aortic root were also assessed. RESULTS: Our analysis revealed that the aortic root does not appreciably dilate following root-sparing operations. In patients with sinus of valsalva diameters of 4.0 and 5.0cm, the average annual aortic root growth rate is 0.046 and 0.057cm/yr (CI: 0.040-0.043), respectively. Furthermore, compared to dilated aortas at 4.0 and 5.0cm in the ascending aorta (0.17cm/yr, 0.21cm/yr; CI: 0.19- 0.22), descending aorta (0.22cm/yr, 0.27cm/yr; CI: 0.24-0.27), and in thoracoabdominal aneurysms (0.19cm/yr, 0.24cm/yr; CI: 0.21-0.24) the aortic root dilates at a significantly attenuated rate. CONCLUSIONS: The aortic root is an embryologically unique tissue within the thoracic aorta and accordingly displays disparate growth characteristics compared to the ascending, arch, and descending components of the aorta. In appropriately selected patients, the risk of recurrent dilation or aneurysm formation at the root following RS operations is small and should not be an acute concern of the clinician, as it most often would require a course of decades to be realized. Root-sparing operations are proven, safe, and technically less challenging means of resecting ascending thoracic aneurysms without significant involvement of the root. Simply put, if the root were destined to dilate aneurysmally, it would have done so over the decades required for the adjacent ascending aneurysm to also develop