Ann Thorac Surg 1996;61:1011-1012
© 1996 The Society of Thoracic Surgeons
Case Report
Dissection of an Allograft Ascending Aorta After Aortic Root Replacement
Julian A. Smith, FRACS,
Timothy C. McKenzie, FRACS,
Bruce B. Davis, FRACS
Department of Cardiothoracic Surgery, Alfred Healthcare Group, Prahran, Victoria, Australia
Accepted for publication August 30, 1995.
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Abstract
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The case of a 57-year-old man with dissection of an allograft ascending aorta 2 months after aortic root replacement is presented. Most likely traumatic in origin, this unusual complication was managed by Dacron graft replacement of the ascending aorta using hypothermia and circulatory arrest.
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Introduction
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The use of human tissue to replace the diseased aortic valve or aortic root has gained popularity in recent times [1]. Cryopreservation is currently the preferred method of allograft preparation and storage before use [2]. Allograft insertion is technically more demanding than that of other aortic valve or root prostheses. Many pathologic conditions including aneurysmal disease and infective endocarditis have been effectively managed with a low incidence of allograft-related complications and excellent early and longer-term results [1, 3, 4]. We report a case of acute dissection of an allograft ascending aorta 2 months after allograft aortic root replacement.
A 57-year-old hypertensive man underwent allograft aortic root replacement for annuloaortic ectasia (ascending aortic diameter in excess of 5 cm) and grade 3 aortic regurgitation. The 27-mm cryopreserved allograft was harvested locally from a previously well 50-year-old man (with no described features of Marfan's syndrome) who died of injuries sustained in a motor vehicle accident. The allograft was cryopreserved and stored at our institution using established techniques [2]. Strict guidelines for allograft acceptance, preservation, and thawing were followed [2].
During allograft implantation, the proximal anastomosis was performed with interrupted 4-0 Ethibond (Ethicon, Somerville, NJ). The coronary artery ostia were attached to the allograft ascending aorta as separate buttons. The distal suture line was completed with continuous 4-0 polypropylene. The postoperative course was uneventful, and hypertension was well controlled with oral ß-blocker therapy. A transthoracic echocardiogram made on discharge from the hospital showed a normal-appearing aortic root and normal allograft function.
The patient recovered rapidly and was without major problems until 2 months postoperatively when he was seen with sudden, severe, nonradiating central chest pain. Vital signs were stable, and there were no new murmurs or chest roentgenographic or electrocardiographic changes. A computed tomographic scan revealed a localized ascending aortic dissection, the true and false lumina, and an anteriorly placed hematoma (Fig 1
). Transesophageal echocardiography showed a mobile flap in the middle part of the ascending aorta with flow between the true lumen and the false lumen, the latter appearing to contain thrombus. There was minimal aortic regurgitation. A diagnosis of ascending aortic dissection of the allograft was made.
The patient underwent emergent operation. Aprotinin was administered, and the chest was opened after femoral artery and femoral venous cannulation. Tough recent adhesions were divided, and a large, contained hematoma was found in front of the ascending aorta, right ventricular outflow tract, and right atrium. After systemic cooling to 19°C, the heart-lung machine was turned off, and the hematoma was entered. A circumferential dissection of the allograft ascending aorta about 1 cm proximal to the distal anastomotic line was found. The false lumen had ruptured into the contained pericardial space on the day of presentation. The dissection did not compromise the coronary artery orifices or the allograft aortic valve and did not involve the native aorta. There was no evidence of local infection.
With the use of hypothermia and circulatory arrest, the distal native ascending aorta was mobilized and subsequently cross-clamped. The heart-lung machine was turned on again after 12 minutes. During rewarming of the patient, the dissected allograft above the aortic valve was replaced with a 30-mm Dacron graft. No native aorta was replaced. The patient required massive blood and blood product administration, which led to a transient elevation of pulmonary artery pressures. Weaning from cardiopulmonary bypass was achieved with the aid of epinephrine and nitric oxide, administration of which was continued in the intensive care unit for 48 hours. The postoperative course was otherwise uncomplicated. Histopathologic study of the excised allograft tissue confirmed acute dissection, but there was no evidence of underlying vessel-wall disease.
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Comment
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Allograft aortic root replacement has been associated with satisfactory results in reported series [5–7]. Early postoperative complications are rare. Dissection of an allograft ascending aorta is very unusual.
A traumatic intimal fracture may have occurred at the time of allograft thawing (thawing too rapidly and unevenly or handling while still frozen), during allograft preparation, or during implantation. There may also have been excess longitudinal tension on the allograft ascending aorta, which resulted in a circumferential intimal split. The presence of intrinsic vessel-wall disease in the donor tissue is unlikely in view of the histopathologic findings.
Our presumption of a traumatic cause dictated that the ascending aorta alone rather than the entire aortic root be re-replaced. Femorofemoral bypass, deep hypothermia, and circulatory arrest allowed safe reentry, identification of the pathologic condition, clamping of the distal native ascending aorta, and subsequent Dacron graft insertion. Nevertheless, the patient will require regular, ongoing surveillance of the aortic root to look for increasing aortic regurgitation, root enlargement, or occult dissection should there be some unidentified intrinsic allograft disease process.
The unusual complication of dissection of an allograft ascending aorta after aortic root replacement has been presented. This was diagnosed and managed along conventional lines, and a satisfactory outcome has been achieved. It is suggested that the intimal aspect of the allograft ascending aorta be closely examined before implantation to exclude any surface fractures that may predispose to subsequent dissection.
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Footnotes
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Address reprint requests to Dr Davis, Department of Cardiothoracic Surgery, Alfred Healthcare Group, Commercial Rd, Prahran, Victoria 3181, Australia.
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References
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- Kirklin JW, Barratt-Boyes BG. Cardiac surgery. 2nd ed. New York: Churchill Livingstone, 1993:498–523.
- O'Brien MF, Stafford EG, Gardner M, et al. The viable cryopreserved allograft aortic valve. J Cardiac Surg 1987;1:153–67.
- O'Brien MF, McGiffin DC, Stafford EG. Allograft aortic valve implantation: techniques for all types of aortic valve and root pathology. Ann Thorac Surg 1989;48:600–9.[Abstract/Free Full Text]
- Haydock D, Barratt-Boyes BG, Macedo T, Kirklin JW, Blackstone E. Aortic valve replacement for active infectious endocarditis in 108 patients. A comparison of freehand allograft valves with mechanical prostheses and bioprostheses. J Thorac Cardiovasc Surg 1992;103:130–9.[Abstract]
- Pagano D, Allen SM, Bosner RS. Homograft aortic valve and root replacement for severe destructive native or prosthetic endocarditis. Eur J Cardio-thorac Surg 1994;8:173–6.[Abstract/Free Full Text]
- Knott-Craig CJ, Elkins RC, Stelzer PL, et al. Homograft replacement of the aortic valve and root as a functional unit. Ann Thorac Surg 1994;57:1501–6.[Abstract/Free Full Text]
- Prager RL, Deschner W, Kong B, et al. Early experience with homograft aortic root replacement for complex aortic pathology. Surgery 1993;114:794–8.[Medline]
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[Abstract]
[Full Text]
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Abstract
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