Asian Cardiovasc Thorac Ann 2008;16:e4-e6
© 2008 Asia Publishing EXchange Ltd
A Rare Cause of Dissection of Ascending Aorta after Aortic Valve Replacement
Zenichi Masuda, MD,
Takashi Murakami, PhD,
Eishun Shishido, MD,
Masahiko Kuinose, PhD
Department of Cardiovascular Surgery, Iwakuni Clinical Center Yamaguchi, Japan
For reprint information contact: Zenichi Masuda, MD, Tel: 81 86 235 7359, Fax: 81 86 235 7431, Email: zenyan{at}aol.com, Department of Cardiovascular Surgery, Okayama University Graduate School of Medicine and Dentistry, 2-5-1, Shikata, Okayama 700-8558, Japan.
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ABSTRACT
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We present a 78-year-old man who developed Stanford type A aortic dissection seven years after aortic valve replacement. At the previous operation, the diameter of the ascending aorta was 40 mm. Three years later, computed tomography revealed the diameter to have expanded to 50 mm. Four years later, the patient developed aortic dissection with entry at the ascending aorta, and a graft replacement was performed.
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INTRODUCTION
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The occurrence of dissection of the ascending aorta (DAA) after aortic valve replacement (AVR) is a rare event.1 The risk factors for developing this complication and the indications for elective replacement of the ascending aorta (AscAo) during or after aortic valve surgery are not fully understood. We present a case of DAA after AVR and discuss the optimal timing and treatment of choice for the dilated AscAo.
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CASE REPORT
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A 70-year-old man with aortic regurgitation had undergone AVR (Carpentier-Edwards prosthesis 23 mm) with the diameter of the AscAo 40 mm, which was left untreated. The aortic valve was tricuspid and the aortic sinus was slightly dilated. He was discharged without any complications. Three years later, a computed tomography (CT) done by the referral doctor revealed an increase in diameter to 50 mm, which was still left untreated. Seven years after AVR, he developed chest discomfort with ST-segment elevation in leads II, III, and aVF by electrocardiogram (EKG). Echocardiography did not detect any abnormality of the bioprosthesis or pericardial effusion. Coronary angiogram did not reveal any stenotic lesion. Eight days later, the enhanced CT revealed Stanford type-A aortic dissection (Figure 1A and 1B
). He was transferred to our hospital for surgery. Bilateral brachial arteries and the right femoral artery were exposed, and median re-sternotomy was performed. A 2-staged venous cannula was inserted into the right atrium and cardiopulmonary bypass (CPB) was established. When the patient was cooled to 28°C, the AscAo was cross clamped in the mid portion and opened. Blood cardioplegia was infused directly into the coronary orifice. An intimal tear was recognized at the posterolateral side 10 mm above the previous aortotomy. Dissection of the ascending aorta was extended to the proximity of the left coronary artery orifice, but the site of the previous aortotomy was left intact. The pseudolumen was ruptured at the posterior wall facing the right pulmonary artery and was sealed with adhesive fibrous tissue. The AscAo was transected at the previous aortotomy and the proximal aortic stump was reinforced with 2 layers of felt strips with interrupted mattress sutures. A one-branched 26 mm graft (UBE shield graft, UBE Medical Co., Ltd., Ube, Japan) was anastomosed to the proximal stump. By the completion of the proximal anastomosis, the patient was cooled below 20°C. With systemic circulatory arrest and cerebral perfusion, the distal AscAo was transected, reinforced in the same fashion and anastomosed. The CPB time, cardiac arrest time and systemic circulatory arrest time were 204, 103 and 18 minutes, respectively. The patient’s postoperative course was uneventful. Pathological examination showed only atheromatous lesions.
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Figure 1. (A) Preoperative enhanced CT; large hematoma seen around the pulmonary bifurcation; dissection extended into the distal thoracic aorta with bilateral pleural effusion, but no pericardial effusion; (B) Preoperative enhanced 3D-CT, Stanford type A aortic dissection with the maximal diameter of the AscAo 70 mm.
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DISCUSSION
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Dissection of the ascending aorta after AVR is a very rare complication observed in 0.6% of all routine AVR.1,2 A history of AVR appears to be one of the most important predisposing conditions for DAA, with an average frequency of 9%.1 Thus the special consideration of the risk stratification and the devising of a strategy of treatment are important. In addition to systemic hypertension and Marfan syndrome, iatrogenic injuries like catheter procedures, cannulation, cross clamp and surgical procedures (AVR or CABG) may be associated with DAA.3
All DAA from cannulation or cross clamp were observed intraoperatively or within a month after AVR.4 Although this patient had previously undergone AVR, the entry site was separate from the site of surgical manipulation; some potential tissue rigidity above the old suture line may have been predisposed to hemodynamic stress with formation of a weak spot for intimal rupture.
Aortic size is generally accepted as an important risk factor for DAA. Davies and colleagues reported a 27-fold increase in the odds ratio for rupture with ascending aorta diameter of > 60 mm.5 If the diameter exceeds 55 mm, preventive graft replacement should be considered. Pieters and colleagues reported the incidence of DAA to be as high as 22% and recommend elective preventive replacement of the AscAo if the diameter > 60 mm.4 Prenger and colleagues advocated a composite graft replacement for patients with progression of a mildly dilated aorta to > 50 mm.2
In addition to the aortic size, other predictive factors for late DAA include bicuspid aortic valve (biAV), age, aortic regurgitation, systemic hypertension and the fragility of the aortic wall. It is well documented that a biAV is associated more with DAA than a tricuspid aortic valve. Furthermore, progressive aortic dilatation cannot be prevented in a biAV by AVR6 suggesting structural differences in the aortic wall with a biAV. Borger and colleagues7 as well as Ergin and colleagues8 suggested concomitant graft replacement if the diameter is > 45 mm in patients with biAV disease.
Regarding the surgical techniques for the dilated AscAo, besides graft replacement, there are two other surgical options: aortoplasty and wrapping. Graft replacement should be advocated when feasible. Taking into consideration the relatively small stature of the Japanese population, the diameter of the AscAo of 40 mm at the age of 70 years and the valve pathology of tricuspid aortic valve, it might have been better if a wrapping had been performed. In addition, the diameter had increased to 50 mm 3 years after AVR the patient might have benefited from an early elective re-operation if he had been referred at this stage. In the case of aortic valve disease with a dilated ascending aorta, various surgical options of dealing with it should be considered at the time of valve replacement.
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REFERENCES
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- von Kodolitsch Y, Loose R, Ostermeyer J, Aydin A, Koschyk DH, Haverich A, et al. Proximal aortic dissection late after aortic valve surgery: 119 cases of a distinct clinical entity. Thorac Cardiovasc Surg 2000;48:342–6.[Medline]
- Prenger K, Pieters F, Cheriex E. Aortic dissection after aortic valve replacement: incidence and consequences for strategy. J Card Surg 1994;9:495–8.[Medline]
- Stanger O, Oberwalder P, Dacar D, Knez I, Ringler B. Late dissection of the ascending aorta after previous cardiac surgery: risk, presentation and outcome. Eur J Cardiothorac Surg 2002; 21:453–8.[Abstract/Free Full Text]
- Pieters FA, Widdershoven JW, Gerardy AC, Geskes G, Cheriex EC, Wellens HJ. Risk of aortic dissection after aortic valve replacement. Am J Cardiol 1993;72:1043–7.[Medline]
- Davies RR, Goldstein LJ, Coady MA, Tittle SL, Rizzo JA, Kopf GS, et al. Yearly rupture or dissection rates for thoracic aortic aneurysms: simple prediction based on size. Ann Thorac Surg 2002;73:17–27.[Abstract/Free Full Text]
- Yasuda H, Nakatani S, Stugaard M, Tsujita-Kuroda Y, Bando K, Kobayashi J, et al. Failure to prevent progressive dilatation of ascending aorta by aortic valve replacement in patients with bicuspid aortic valve: comparison with tricuspid aortic valve. Circulation 2003;108(suppl 1): II291–4.[Medline]
- Borger MA, Preston M, Ivanov J, Fedak PW, Davierwala P, Armstrong S, et al. Should the ascending aorta be replaced more frequently in patients with bicuspid aortic valve disease? J Thorac Cardiovasc Surg 2004;128:677–83.[Abstract/Free Full Text]
- Ergin MA, Spielvogel D, Apaydin A, Lansman SL, McCullough JN, Galla JD, et al. Surgical treatment of the dilated ascending aorta: when and how? Ann Thorac Surg 1999;67:1834–9.[Abstract/Free Full Text]
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ABSTRACT
INTRODUCTION
