Cardiovascular Pathology xxx (2014) xxx–xxx
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Cardiovascular Pathology
Case Report
An unusual case of a congenital aorto-left atrial tunnel Marco Di Eusanio a,⁎, Elena Biagini b, Gaetano Gargiulo a, Roberto Di Bartolomeo a, Massimiliano Lorenzini b, Marinella Ferlito b, Ferdinando Pasquale b, Sebastiano Castrovinci a, Claudio Rapezzi b, Robert H Anderson c a Cardiac Surgery Division, Department of Experimental Diagnostic and Specialty Medicine, Sant’Orsola Malpighi Hospital, Alma Mater Studiorum — University of Bologna, 40123 Bologna, Italy b Cardiology Division, Department of Experimental Diagnostic and Specialty Medicine, Sant’Orsola Malpighi Hospital, Alma Mater Studiorum — University of Bologna, 40123 Bologna, Italy c Institute of Genetic Medicine, Newcastle University, Tyne and Wear NE1 3BZ, United Kingdom
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Article history: Received 8 September 2013 Received in revised form 8 February 2014 Accepted 10 February 2014 Available online xxxx
a b s t r a c t Most usually, the aortic tunnels empty into the left ventricle. Very rarely, they open to the left atrium. The essence of the aortic tunnels is that they bypass the hinges of the valvar leaflets within the aortic root. We have recently encountered an aorto-left atrial tunnel satisfying this criterion. © 2014 Elsevier Inc. All rights reserved.
Keywords: Aorto-left atrial tunnel Congenital
1. Case report The male patient, aged 67 years, with an unremarkable medical history, was admitted to our hospital with fever. The electrocardiogram revealed atrial fibrillation, with bi-fascicular block. Laboratory tests revealed mild leukocytosis, and blood cultures were negative. Transthoracic and transesophageal echocardiograms (Fig. 1) showed a communication from the aorta to the left atrium, which extended through the area of aortic-to-mitral valvar fibrous continuity and entered the atrium through the two openings in the middle part of the aortic leaflet of the mitral valve. The left coronary leaflet of the aortic valve was severely thickened and prolapsed, but regurgitation across the valvar orifice was minimal. No vegetations were observed on either the aortic or mitral valvar leaflet. The left ventricle (LV) was severely dilated (left ventricular end-diastolic volume, LVEDV=123 ml/m 2) and the ejection fraction was 56%. The computerized tomographic angiographic scan confirmed echocardiographic findings and excluded any significant coronary arterial disease. Despite the absence of valvar vegetations, there remained the potential diagnosis of active infective endocarditis, so antibiotic therapy was started, and shortly thereafter, the patient was referred for surgical repair. The procedure was performed using median sternotomy, cardiopulmonary bypass, and cardioplegic arrest. Upon visual inspection, the aortic
Funding: No funding to disclose. ⁎ Corresponding author. Cardiac Surgery Division, Department of Experimental Diagnostic and Specialty Medicine, Sant’Orsola Malpighi Hospital/Alma Mater Studiorum — University of Bologna, Via Massarenti n9, 40138 Bologna, Italy. Tel.: +39-0516364483. E-mail address:
[email protected] (M. Di Eusanio).
root showed no signs of either dilatation or rupture or dissection. The tunnel was discovered; its proximal opening was located in the left coronary aortic sinus 1 cm below the orifice of the left coronary artery; the tunnel then extended into the substance of the aortic leaflet of the mitral valve and emptied into the left atrium through two openings in the middle portion of the aortic leaflet of the mitral valve, with diameters of 6 and 3 mm, respectively. The left coronary aortic leaflet was dysmorphic, with tissue excess and no vegetation, and bulged markedly into the LV outflow tract (Fig. 2). The three leaflets coapted well. Surgical repair consisted in the closure of the proximal opening of the tunnel with a pericardial patch and resection of the upper portion of the aortic leaflet of the mitral valve that formed the roof of the atrial segment of the tunnel. The left coronary aortic leaflet was resected and a new leaflet was created using a porcine pericardial patch (Vascutek Ltd, Swillington, United Kingdom). Intra-operative findings and the subsequent microbiological and histological examination of the excised tissue firmly excluded both active infective endocarditis and inflammatory processes (no inflammatory cells, no acute neither fibrotic vegetations). The patient was discharged uneventfully, echocardiography at that time showing a satisfactory repair with LVEDV reduction (86 ml/m 2). 2. Comment Our patient has an exceedingly rare lesion that fulfills the criterions for description as an aorto-left atrial tunnel. Aortic tunnels in any guise are rare. They usually take their origin from the coronary aortic sinuses, with their phenotypic feature being that they bypass the hinges of the valvar leaflets as they extend to open into the LV [1,2]. Such tunnels, again with the phenotypic feature of bypassing the
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Please cite this article as: Di Eusanio M, et al, An unusual case of a congenital aorto-left atrial tunnel, Cardiovasc Pathol (2014), http://dx.doi.org/ 10.1016/j.carpath.2014.02.002
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M. Di Eusanio et al. / Cardiovascular Pathology xxx (2014) xxx–xxx
Fig. 1. Panel A is a transesophageal echocardiographic view at 135° that shows the left atrial segment of the tunnel, which passes through the middle component, A2, of the aortic leaflet of the mitral valve. The left coronary leaflet of the aortic valve is thickened and bulges into the LV outflow tract. Panel B is a color Doppler opening of the tunnel into the left atrium, producing a systo-diastolic shunt. Panel C is a three-dimensional transesophageal echocardiographic image. In all panels, the roof of the tunnel is evident above the A2 component of the mitral valve (arrows).
Fig. 2. Intraoperative view: The thickened left coronary aortic valve leaflet (black arrow) is well seen, as is the aortic opening (white arrow) of the tunnel (Panel A). A surgical instrument is inserted into the tunnel (Panel B). Panel C shows the opening of the tunnel into the left atrium through an orifice in the anterior mitral leaflet.
Fig. 3. The cartoon shows the course of the aorto-left atrial tunnel. LA, left appendage; LMS, left main stem; TV, tricuspid valve; AML, anterior mitral leaflet; PML, posterior mitral leaflet.
Please cite this article as: Di Eusanio M, et al, An unusual case of a congenital aorto-left atrial tunnel, Cardiovasc Pathol (2014), http://dx.doi.org/ 10.1016/j.carpath.2014.02.002
M. Di Eusanio et al. / Cardiovascular Pathology xxx (2014) xxx–xxx
hinge of the aortic valvar leaflet, can also extend to open into the right ventricle [1,2]. In our patient, the tunnel opened from the left coronary aortic sinus, bypassed the hinge of the left coronary aortic valvar leaflet, and then passed through the area of aortic-to-mitral valvar continuity, opening into the left atrium through two orifices in the mitral valvar leaflet (Fig. 3). We find it remarkable that the patient could have survived the age of 67 years without showing previous clinical signs of the tunnel. This history would be more suggestive of acquired disease. Against the hypothesis of an acquired lesion is the fact that the course of the communication is exactly the same as other so-called tunnels, in that the lesion bypasses the hinge of the aortic valve, then passes through the area of aortic-to-mitral valvar continuity, opening into the left atrium through two orifices in the mitral valvar leaflet (Fig. 3). Furthermore, there is no evidence from the histology to support the notion of either acute or chronic infection, and the track of the communication is such that it is more likely to have arisen when the aortic root was surrounded by loose muscular and mesenchymal tissue during development than when it had become totally fibrous in postnatal life. Nevertheless, the alternative diagnosis of endocarditis was excluded by the lack of any findings of inflammatory involvement and by the lack of any vegetations. Moreover, the left coronary leaflet of the aortic valve was dysmorphic and showing a remarkable excess tissue, characteristics that strongly suggested an associated congenital valvar malformation rather than a previous destructive infective disease. If individuals with congenital aortic-cameral communications most frequently develop congestive heart failure in the first year of life, it is possible that, in our case, the narrow and long communication prevented a significant left ventricular overload. A less-than-significant LV overload could explain the slower course of the disease in our patient that, anyhow, presented with a severely dilated LV, inexplicable otherwise. The balance of probability, therefore, remains that the structure is congenital, even though we cannot, with 100% certainty, rule out an acquired etiology.
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The course of the lesion in our patient is strikingly different from previous ones described in the literature as producing fistulous communications between the aorta and the left atrium [3]. Indeed, none of these previous cases had the feature of bypass of the hinge of an aortic valvar leaflet, which is a key point in the differential diagnosis between congenital tunnel and aneurysm of sinus of Valsalva with fistula. The aortic tunnels almost certainly reflect abnormal excavation of the leaflets of the valve during their formation from the cushions that are formed within the ventricular outflow tract during embryological development [4]. The cushions, as they excavate, are contained with a turret of myocardium, with the dorsal wall of this turret initially formed by a myocardial fold between the developing aortic root and the developing aortic leaflet of the mitral valve. The tunnel in our patient must have been formed by excavation within this area of continuity, the muscular tissues becoming fibrous with ongoing development. It is, perhaps, surprising that the patient reached the age of 67 years without serious problems, but all the evidence points to the lesion being congenital rather than acquired. It is the feature of the bypass of the hinge of the aortic valvar leaflet that supports its diagnosis as an aorto-left atrial tunnel.
References [1] McKay R, Anderson RH, Cook AC. The aorto-ventricular tunnels. Cardiol Young 2002;12:563–80. [2] Anderson RH, Cook A, Brown NA, Henderson DJ, Chaudhry B, Mohun T. Development of the outflow tracts with reference to aortopulmonary windows and aortoventricular tunnels. Cardiol Young 2010;20:92–9. [3] Archer TP, Mabee SW, Baker PB, Orsinelli DA, Leier CV. Aorto-left atrial fistula. A reversible cause of acute refractory heart failure. Chest 1997;111:828–31. [4] Anderson RH, Chaudhry B, Mohun TJ, Bamforth SD, Hoyland D, Phillips HM, Webb S, Moorman AF, Brown NA, Henderson DJ, et al. Normal and abnormal development of the intrapericardial arterial trunks in humans and mice. Cardiovasc Res 2012;95:108–15.
Please cite this article as: Di Eusanio M, et al, An unusual case of a congenital aorto-left atrial tunnel, Cardiovasc Pathol (2014), http://dx.doi.org/ 10.1016/j.carpath.2014.02.002
