Editorial Comment: Remodelling of the sinotubular junction to correct aortic insufficiency

‘Life is short, the art long, opportunity fleeting, experience treacherous, judgement difficult’ In this issue of the Journal, Schäfers' group from the University Hospital of Saarland, Germany has another important contribution on operative procedures to preserve the aortic valve in patients with aortic insufficiency (AI) [1]. From a cohort of 1094 patients who had conservative operations on the aortic valve at that institution, the authors examined the records of a cohort of 144 patients who had moderate or severe AI and dilated sinotubular junction (STJ). The operation consisted in adjusting the diameter of the STJ by replacement of the ascending aorta with a tubular Dacron graft of appropriate diameter and correcting aortic cusp prolapse, which was present in all but four patients. The cusp prolapse was repaired by plication of its central portion or by using a pericardial patch to reinforce or augment the cusp. In addition, reduction in the aorto-ventricular junction (AVJ) was performed by sub-commissural plication in 59 patients and by a circular suture with expanded polytetrafluoroethylene suture in 23. Most patients had congenital aortic valve disease (41% bicuspid and 19% unicuspid aortic valve). They analysed the entire cohort and the subgroups of patients with congenital aortic valve disease and with tricuspid aortic valve. As with any aortic valve preserving technique in the setting of dilated aorta, selection of the diameter of the graft is difficult and there is NO consensus on what is the best method. The authors used the patient's body surface area to choose the size of the graft to correct the dilated STJ. Most surgeons believe that the ‘normal’ diameter of the STJ can be estimated by transecting the aorta immediately above the STJ and pulling on the commissures upward while observing the position of the cusps. Once cusp coaptation is optimal, the diameter of an imaginary circle that includes all commissures is the ideal diameter of the STJ [2–4]. This manoeuvre also helps the surgeon to assess cusp prolapse before replacing the ascending aorta. The anastomosis between the selected graft and the aortic root deserves a comment. Since the diameter of the STJ is larger than the diameter of the Dacron graft and the dilation of the STJ is asymmetric, the suture line must correct the diameter of the STJ and its asymmetric dilation while taking into account the fact that the aortic cusps have different sizes with consequent different inter-commissural distances. As described by Asano et al. [1], the Dacron graft is sutured to the aortic root first at the level of the STJ and after that the cusps are inspected for prolapse. The rate of cusp prolapse in their series was much higher than in ours, but most of our patients had tricuspid aortic valve and none had unicuspid aortic valve [3]. Patients with bicuspid and unicuspid aortic valve and AI invariably require cusp repair. The authors used a multitude of techniques to repair cusp prolapse, probably because of a large proportion of patients with congenital aortic valve disease. This makes the interpretation of the outcomes difficult. However, their mid-term results on patients with tricuspid aortic valve and dilated STJ were excellent and similar to those reported by other surgeons [3, 5]. We believe that patients with tricuspid aortic valve and AI due to dilated STJ are the ones that benefit most from this type of conservative aortic valve surgery [3]. They are older and usually the aneurysm involves primarily the ascending aorta and it causes AI because of secondary dilation of the STJ [3]. The aortic sinuses are normal (<40 mm in diameter), the aortic cusps are relatively small and the aortic annulus is normal [6]. Sometimes, the aortic cusps are too small to seal the AVJ because of loss of elastic fibres and increase in fibrous tissue and consequent mismatch between aortic cusps/AVJ areas. Aortic valve replacement with supra-coronary replacement of the ascending aorta IS probably a safer procedure in older patients with small and sclerotic aortic cusps. The authors believed their results in patients with congenital aortic valve disease were satisfactory. Although the 5-year survival was excellent, the freedom from moderate or severe AI and the freedom from reoperation fell short of satisfactory in my view at 73.4 and 82%, respectively. The authors found that the need for pericardial patch of aortic cusp and AVJ > 28 mm were associated with higher risk of valve failure by univariate analysis, and only AVJ > 28 mm by multivariate analysis. Given the sample size of this subgroup of patients and the number of adverse events, the value of multivariate analysis is questionable. However, since it has been shown that incompetent bicuspid aortic valves are often associated with dilated AVJ [7], the authors' finding that AVJ > 28 mm was predictive of recurrent AI and reoperation is probably well-founded. If this is this the case, it is also reasonable to assume that sub-commissural plication failed to correct the problem of AVJ dilation. We believe that patients with bicuspid aortic valve and dilated AVJ are best treated with reimplantation of the aortic valve [8]. Indeed, in a recent report from another experienced group with aortic valve repair, patients with bicuspid aortic valve who had the reimplantation procedure had better clinical results than those who had other types of repair in a case-matched study [9]. The freedom from moderate or severe AI at 6 years was 100% in the reimplantation group and 77% in the valve repair group [9]. The authors, de Kerchove et al. [9], concluded that ‘in bicuspid aortic valve repair, root replacement with the reimplantation technique stabilizes the ventriculoaortic junction, improves valve mobility (low gradient), and is associated with improved outcomes’. Clearly, more information is needed on late outcomes of various approaches to treat patients with AI due to dilation of the aorta. Aortic valve sparing operations for aortic root aneurysms have now been done for over two decades and we believe that currently available information supports the contention that young patients are best treated with reimplantation of the aortic valve, whereas older patients with normal AVJ can have equally good results with remodelling of the aortic root [10]. Other types of aortic valve preserving procedures such as the one described by Asano et al. [1], and in particularly repair of bicuspid aortic valve need more data and longer follow-up to better assess the multitude of approaches used to correct AI in these patients.

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