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J Thorac Cardiovasc Surg 2004;128:753-756
© 2004 The American Association for Thoracic Surgery
Brief communication |
a Division of Cardiac Surgery, University of Verona, Verona, Italy
Received for publication February 10, 2004; revisions received March 5, 2004; accepted for publication March 15, 2004.
* Address for reprints: Giovanni Battista Luciani, MD, Division of Cardiac Surgery, University of Verona, O. C. M. Piazzale Stefani 1, Verona, 37126 Italy
gbluciani{at}yahoo.com
Aortic valve replacement with the pulmonary autograft (ie, the Ross operation) is generally associated with satisfactory early and late results. Complications, however, can occur, including the tendency of the pulmonary autograft root to dilate with time.1 Whereas neoaortic root dilatation might be observed in as many as one third of patients late after the Ross operation,2 uncertainty still exists as to the rate of progression toward true aneurysmal disease (aortic diameter 
5 cm).1,2 Furthermore, the actual risk of complications, such as neoaortic rupture or dissection, is also unknown. The yet undefined natural history of root dilatation after the Ross operation, the often satisfactory competence of the pulmonary autograft valve, the scarcity of valid therapeutic alternatives (particularly in the infant and child), and the complexity–risk of reintervention have thus far delayed standardization of therapeutic indications. In particular, timing and technique of reoperation on the aneurysmal neoaortic root are still controversial.1,2
Here we present a case of potentially lethal evolution of progressive pulmonary autograft dilatation (ie, neoaortic root dissection) successfully treated with valve-sparing root replacement. The implications in terms of natural history and indications for reintervention are discussed.
Clinical summary
A 29-year-old man with a long-standing history of aortic valve regurgitation on the bicuspid aortic valve and mild dilatation of the aortic root underwent elective aortic root replacement with the pulmonary autograft on October 18, 1994. The right ventricular outflow tract was reconstructed with a 28-mm pulmonary homograft. Postoperative recovery was uneventful, and discharge echocardiography showed competent semilunar valves and normal aortic root diameter. Two years after the operation, moderate dilatation of the aortic root (maximum diameter, 46 mm) was identified at yearly echocardiographic examination. The aortic valve, however, was competent, and the patient was completely symptom free. Subsequent examinations confirmed progressive root dilatation, which reached true aneurysmal dimensions 8 years after the operation. The latest measurement showed a left ventricular aortic junction (aortic annulus) diameter of 32 mm, a sinus of Valsalva diameter of 48 mm, and a sinotubular junction and proximal ascending aortic diameter of 54 mm. The aortic valve presented with mild regurgitation, and mild obstruction of the pulmonary homograft (peak pressure gradient of 24 mm Hg) was also identified. Although the patient remained asymptomatic, elective resection of the root aneurysm was recommended, and preoperative angiographic examination was scheduled. On admission for preoperative screening on July 16, 2003, the patient reported the recent onset of mild exertional dyspnea.
Repeat echocardiographic examination of the aortic root suggested a further increase in maximum root diameter (63 mm at the sinus of Valsalva portion), with the presence of an intimal flap image. Aortic valve function had worsened to produce moderate insufficiency, and mild dilatation of the left ventricle (left ventricular end-diastolic dimension of 65 mm) with normal systolic function (ejection fraction of 65%) was also present. These findings were corroborated by means of aortic angiography, showing severe aortic root dilatation with straightening of the posterior profile of the root, which suggested the presence of an intimal flap (Figure 1). Valve insufficiency was graded as mild, and the results of coronary angiography were normal. Magnetic resonance scanning of the ascending aorta confirmed the diagnosis of aortic root aneurysm, with dissection limited to the root itself. The distal ascending aorta, the arch, and the descending thoracic aorta were unremarkable. Given the likelihood of acute or subacute neoaortic root dissection, the patient was transferred to our unit for urgent repair. On sternal re-entry, marked dilatation of the aortic root was identified. By using mildly hypothermic cardiopulmonary bypass, the distal ascending aorta was crossclamped, and the heart was arrested with retrograde blood cardioplegia. After transection of the aorta at the level of the distal aortic anastomosis, marked thinning of the aortic root wall was evident. An intimal flap extending from the level of the aortotomy to the noncoronary sinus of Valsalva was found. The left and right coronary sinuses were intact.
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Despite widespread satisfaction with the clinical outcome of the Ross operation, awareness of its early and late shortcomings is growing.1,2 Neoaortic root dilatation has since emerged as the most common complication, particularly when the autograft is implanted with the complete root replacement technique.1,2 The proportion of patients with root dilatation who show progression toward true neoaortic aneurysm (aortic diameter 5 cm) and the rate of progression are matters of controversy.1,2 Quite clearly, however, progressive autograft root dilatation has been shown to cause neoaortic valve insufficiency.2,3 This observation explains the increasing number of recent reports on elective reoperations for autograft root aneurysm.3-8 Therapeutic indications with regard to timing and technique of reintervention have thus far been elusive.1,2 Several factors account for the absence of standardized criteria for reoperation, including the undefined natural history of autograft root dilatation, the possible coexistence of a competent neoaortic valve, the scarcity of valid surgical alternatives, and the complexity of redo aortic root procedures with the attendant morbidity.9 In general, elective intervention on the neoaortic root has been advised in the presence of moderate or severe neoaortic valve insufficiency or when the aortic root diameter exceeded 55 mm.1,3-8 Some authors have also deferred reintervention on the basis of the severity of concomitant pulmonary homograft dysfunction, with the intent to minimize the number of reoperations.4 The technique most commonly adopted to replace the dilated aortic root has been the modified Bentall operation using composite mechanical or biologic grafts, with valve-sparing root replacement limited to anecdotal reports.4-8 By using this approach, morbidity associated with reoperation has been low. However, the proportion of patients benefiting from neoaortic valve preservation has also proved low, as low as one third of those requiring reintervention.4 Our initial approach to the problem of root aneurysm after the Ross procedure has been cautious, thereby delaying reoperation until the appearance of moderate valve insufficiency and progressive left ventricular enlargement. This has resulted in only 1 of 3 patients, the present one, having successful root remodeling with valve preservation (Table 1). The case here reported provides evidence that progressive neoaortic root dilatation after the Ross procedure might be complicated by aortic root dissection. From a clinical and histologic standpoint, the presentation is identical to that of native aortic dissection. However, involvement is limited to the aortic root by the distal anastomotic suture line. Whereas brachiocephalic and thoracoabdominal aortic collaterals will be protected by the disease process, any proximal aortic complication is possible, including aortic valve regurgitation, coronary occlusion, or aortic rupture. Although clinically relevant valve insufficiency appeared subtly in the case herein, the untoward events reported above can all occur acutely. Given the impossibility to quantify the risk of neoaortic root rupture and the young age of the patient, indication for reintervention was thus planned on an urgent basis, even in the absence of marked clinical symptomatology. Contrary to the attitude thus far adopted, early treatment of neoaortic root dilatation deserves consideration regardless of valve function because life-threatening complications, such as neoaortic root dissection, are a definite risk.
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On the basis of the present report, life-threatening complications of neoaortic root aneurysm, such as dissection or even rupture, are distinct possibilities. Elective resection of the autograft root aneurysm should not be delayed until evidence of valve involvement shows but rather scheduled prophylactically in relation to morphometric parameters, as suggested for the native aortic aneurysm in patients with Marfan syndrome or bicuspid aortic valve disease.11 Earlier indication for reoperation might reduce the risk of spontaneous neoaortic root complications and increase the likelihood of autograft valve preservation.
References
This article has been cited by other articles:
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  R. C. Elkins, D. M. Thompson, M. M. Lane, C. C. Elkins, and M. D. Peyton Ross operation: 16-year experience J. Thorac. Cardiovasc. Surg., September 1, 2008; 136(3): 623 - 630. [Abstract] [Full Text] [PDF]
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L. M.A. Klieverik, J. J.M. Takkenberg, B. C.J. Elbers, F. B.S. Oei, L. A. van Herwerden, and A. J.J.C. Bogers Dissection of a dilated autograft root J. Thorac. Cardiovasc. Surg., March 1, 2007; 133(3): 817 - 818. [Full Text] [PDF]
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 N. Watanabe, S. Saito, H. Saito, and H. Kurosawa Valve-sparing aortic root replacement with repair of leaflet prolapse after Ross operation Interactive CardioVascular and Thoracic Surgery, February 1, 2007; 6(1): 89 - 91. [Abstract] [Full Text] [PDF]
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P. H. Schoof, J. J.M. Takkenberg, R.-J. van Suylen, P. E. Zondervan, M. G. Hazekamp, R. A.E. Dion, and A. J.J.C. Bogers Degeneration of the pulmonary autograft: An explant study J. Thorac. Cardiovasc. Surg., December 1, 2006; 132(6): 1426 - 1432. [Abstract] [Full Text] [PDF]
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