European Journal of Cardio-Thoracic Surgery Advance Access published January 20, 2014
Formation of multiple conduit aneurysms following Matrix P® conduit implantation in a boy with tetralogy of Fallot and pulmonary atresia David Backhoff*, Michael Steinmetz, Matthias Sigler and Heike Schneider Department of Paediatric Cardiology and Intensive Care Medicine, Georg-August-University Hospital Göttingen, University of Göttingen, Göttingen, Germany * Corresponding author. Department of Paediatric Cardiology and Intensive Care Medicine, Georg-August-University Hospital Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany. Tel: +49-551-3922550; e-mail: [email protected] (D. Backhoff ). Received 21 August 2013; received in revised form 2 December 2013; accepted 6 December 2013
Abstract We report on a 6-year old boy with tetralogy of Fallot and pulmonary atresia in whom a 16 mm Matrix P® conduit was implanted between the pulmonary artery and the right ventricle at the age of 16 months. Five years later he developed severe stenosis of the distal conduit anastomosis. The notable findings were several aneurysms of the conduit proximal to the distal stenosis within the high-pressure region. The wall of the aneurysms contained xenogeneic conduit tissue without inflammatory or foreign-body response. We believe that aneurysm formation of the conduit was a result of fatigue of the conduit wall under suprasystemic pressure. Keywords: Decellularized porcine conduit • Matrix P® conduit • Tetralogy of Fallot • Aneurysm
CASE REPORT We present the case of a 6-year old boy with tetralogy of Fallot, pulmonary atresia, multiple aortopulmonary collateral arteries though hypoplastic confluent central pulmonary arteries, as shown by cardiac catheterization within the first month of life. No syndromal disorder was suspected in the boy. At the age of 10 weeks, surgical pulmonary artery unifocalization was performed in combination with a central 5 mm aortopulmonary shunt. At the age of 16 months, surgical correction was performed: the central shunt was taken down, the ventricular septal defect was closed and both pulmonary arteries were enlarged by the use of a bovine pericardial patch (Cardiofix, CarboMedics, Inc., Austin, TX, USA). A 16 mm decellularized Matrix P® conduit (AutoTissue, Berlin, Germany) was implanted between the pulmonary artery bifurcation and the right ventricle with a tubular bovine pericardial patch extension (Cardiofix, CarboMedics, Inc.) at the proximal anastomosis. At follow-up examinations, the boy was doing fine and played in a local football team where he showed good physical capacity. At the age of 6 years, he was readmitted to our institution with significant conduit stenosis. At this time, he did not show any signs of congestive heart failure. Echocardiography showed severe conduit stenosis (Vmax 5.1 m/s, mean systolic gradient 52 mmHg) with moderate regurgitation and significantly enlarged and hypertrophied right ventricle with mildly impaired function. Using continuous wave-Doppler echocardiography of a mild-to-moderate tricuspid regurgitation, systolic right ventricular pressure was assessed as suprasystemic. Left ventricular parameters were within normal limits. Cardiac catheterization revealed severe stenosis of the conduit with reduction of the lumen to 7 mm at the distal anastomosis. Peak systolic pressure gradient between the right ventricle and the central pulmonary artery was 60 mmHg.
Angiography of the right ventricular outflow tract and subsequent cardiac magnetic resonance imaging revealed the presence of multiple aneurysms: the largest aneurysmatic formation arose from the lateral portion of the conduit with a diameter of 10 mm at the neck and a maximum size of the aneurysm of 27 × 24 mm. There was evidence of three small aneurysms in the distal right ventricular outflow tract (Fig. 1). Surgical conduit replacement was performed uneventfully: after en bloc explantation of the Matrix P® conduit and the proximal aneurysms, a 22 mm—Hancock Conduit (Medtronic, Minneapolis, MN, USA) was implanted. Both pulmonary arteries were reconstructed using a cell-free equine pericardial Matrix patch (AutoTissue, Berlin, Germany). Pathological examination of the explant proved the origin of the aneurysms to be within the Matrix conduit just below the level of the valve (Fig. 2A). There was no relation of this origin to the sutures of the proximal anastomosis. On histopathological examination, we found only few fibroblasts having colonized the conduit wall (Supplementary Figure S1). The wall of the largest aneurysm consisted almost cell-free conduit tissue without any significant inflammatory or foreign-body response (Fig. 2B).
DISCUSSION Narrowing and obstruction of the right ventricular outflow tract is the key issue in a variety of congenital heart diseases such as tetralogy of Fallot. Reconstruction of the right ventricular outflow tract often requires the implantation of a valved conduit with pulmonary homografts being considered as gold standard. However, pulmonary homografts offer a number of disadvantages such as limited availability in small sizes, lack of growth and fast deterioration in
© The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
CASE REPORT
CASE REPORT
European Journal of Cardio-Thoracic Surgery (2014) 1–3 doi:10.1093/ejcts/ezt635
2
D. Backhoff et al. / European Journal of Cardio-Thoracic Surgery
Figure 1: (A and B) anteroposterior and lateral angiograms of the right ventricular outflow tract. A large aneurysm (27 × 24 mm, arrows) with a small neck (10 mm) is evident proximal to the significant stenosis of the distal conduit anastomosis. There are three smaller aneurysms (asterisks) which are also proximal to the distal stenosis and therefore in the high-pressure region of the conduit. The right ventricular outflow tract is significantly dilated. (C and D) 3D virtual reality reconstruction of magnetic resonance imaging gadolinium angiogram of the right ventricle and the right ventricular outflow tract illustrating the findings.
infancy [1]. In our institution, we therefore use pulmonary homografts predominantly in adolescents or young adults and bioprosthetic conduits in younger patients. The introduction of decellularization of xenogenous materials into clinical practice gave hope for improved biomechanical properties, decreased immunogenicity and growth of the conduits [2, 3]. Decellularization is a special chemical process that removes all cellular elements of xenogenous tissue, leaving only a connective tissue scaffold that is colonized by the host’s cells after implantation [2]. The Matrix P® is such a decellularized porcine pulmonary conduit which was available in Europe from 2004 to 2009. The succeeding model now is
reinforced by surrounding glutaraldehyde-fixed equine pericardial patches which—serving as interposit—additionally facilitate connection. The group of the inventor published an actuarial freedom from reoperation or reintervention of 90% 4 years after implantation [2]. It is of note, however, that other centres reported notably less favourable results [4, 5]. In our patient, 5 years after implantation, we found the Matrix P® conduit to be severely obstructed at the level of the distal anastomosis, which has been identified as the major problem in other patients before [5]. The main and notable finding in our patient was the formation of multiple aneurysms of the
3
CASE REPORT
D. Backhoff et al. / European Journal of Cardio-Thoracic Surgery
Figure 2: (A) Explanted Matrix P® conduit (inferior view). The entry to the largest aneurysm (white arrows) is just below the level of the valve (asterisk). (B) Histopathological examination of the wall of the largest aneurysm (haematoxylin and eosin staining). The endocardial surface is smooth. Marker depicts the almost cell-free subentothelial layer—identified as conduit tissue. There is no prominent inflammatory or foreign-body response.
conduit below the level of the valve. Formation of pseudoaneurysms following Matrix P® implantation has been described before [4]. Conduit dissection allowing blood flow in the thickness of the conduit wall is a possible explanation for formation of pseudoaneurysms and has also been observed by Rüffer et al. [5]. In our case, histopathological examination revealed formation of true aneurysms (consisting of xenogenic conduit tissue) which has not been reported in Matrix type conduits before. Entry of the aneurysms was formed by conduit wall; failure of the sutures at the proximal anastomosis could therefore be ruled out as the underlying mechanism. A possible explanation may be that decreased colonialization of the xenogenous conduit with the patient’s fibroblast probably led to unfavourable biomechanical properties during the long-term course. In our patient, we therefore believe that aneurysm formation of the conduit was a result of fatigue of the conduit wall under suprasystemic pressure. This severe complication should be kept in mind when patients with Matrix-type conduits are attended during the long-term course.
SUPPLEMENTARY MATERIAL Supplementary material is available at EJCTS online.
Funding No external funding was secured for this study. Conflict of interest: none declared.
REFERENCES [1] Tweddell JS, Pelech AN, Frommelt PC, Mussatto KA, Wyman JD, Fedderly RT et al. Factors affecting longevity of homograft valves used in right ventricular outflow tract reconstruction for congenital heart disease. Circulation 2000;102(19 Suppl 3):III130–5. [2] Konertz W, Angeli E, Tarusinov G, Christ T, Kroll J, Dohmen P et al. Right ventricular outflow tract reconstruction with decellularized porcine xenografts in patients with congenital heart disease. J Heart Valve Dis 2011;20: 341–7. [3] Konuma T, Devaney EJ, Bove EL, Gelehrter S, Hirsch JC, Tavakkol Z et al. Performance of CryoValve SG decellularized pulmonary allografts compared with standard cryopreserved allografts. Ann Thorac Surg 2009;88: 849–54; discussion 554-5. [4] Perri G, Polito A, Esposito C, Albanese SB, Francalanci P, Pongiglione G et al. Early and late failure of tissue-engineered pulmonary valve conduits used for right ventricular outflow tract reconstruction in patients with congenital heart disease. Eur J Cardiothorac Surg 2012;41:1320–5. [5] Rüffer A, Purbojo A, Cicha I, Glöckler M, Potapov S, Dittrich S et al. Early failure of xenogenous de-cellularised pulmonary valve conduits—a word of caution! Eur J Cardiothorac Surg 2010;38:78–85.
Formation of multiple conduit aneurysms following Matrix P® conduit implantation in a boy with tetralogy of Fallot and pulmonary atresia David Backhoff*, Michael Steinmetz, Matthias Sigler and Heike Schneider Department of Paediatric Cardiology and Intensive Care Medicine, Georg-August-University Hospital Göttingen, University of Göttingen, Göttingen, Germany * Corresponding author. Department of Paediatric Cardiology and Intensive Care Medicine, Georg-August-University Hospital Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany. Tel: +49-551-3922550; e-mail: [email protected] (D. Backhoff ). Received 21 August 2013; received in revised form 2 December 2013; accepted 6 December 2013
Abstract We report on a 6-year old boy with tetralogy of Fallot and pulmonary atresia in whom a 16 mm Matrix P® conduit was implanted between the pulmonary artery and the right ventricle at the age of 16 months. Five years later he developed severe stenosis of the distal conduit anastomosis. The notable findings were several aneurysms of the conduit proximal to the distal stenosis within the high-pressure region. The wall of the aneurysms contained xenogeneic conduit tissue without inflammatory or foreign-body response. We believe that aneurysm formation of the conduit was a result of fatigue of the conduit wall under suprasystemic pressure. Keywords: Decellularized porcine conduit • Matrix P® conduit • Tetralogy of Fallot • Aneurysm
CASE REPORT We present the case of a 6-year old boy with tetralogy of Fallot, pulmonary atresia, multiple aortopulmonary collateral arteries though hypoplastic confluent central pulmonary arteries, as shown by cardiac catheterization within the first month of life. No syndromal disorder was suspected in the boy. At the age of 10 weeks, surgical pulmonary artery unifocalization was performed in combination with a central 5 mm aortopulmonary shunt. At the age of 16 months, surgical correction was performed: the central shunt was taken down, the ventricular septal defect was closed and both pulmonary arteries were enlarged by the use of a bovine pericardial patch (Cardiofix, CarboMedics, Inc., Austin, TX, USA). A 16 mm decellularized Matrix P® conduit (AutoTissue, Berlin, Germany) was implanted between the pulmonary artery bifurcation and the right ventricle with a tubular bovine pericardial patch extension (Cardiofix, CarboMedics, Inc.) at the proximal anastomosis. At follow-up examinations, the boy was doing fine and played in a local football team where he showed good physical capacity. At the age of 6 years, he was readmitted to our institution with significant conduit stenosis. At this time, he did not show any signs of congestive heart failure. Echocardiography showed severe conduit stenosis (Vmax 5.1 m/s, mean systolic gradient 52 mmHg) with moderate regurgitation and significantly enlarged and hypertrophied right ventricle with mildly impaired function. Using continuous wave-Doppler echocardiography of a mild-to-moderate tricuspid regurgitation, systolic right ventricular pressure was assessed as suprasystemic. Left ventricular parameters were within normal limits. Cardiac catheterization revealed severe stenosis of the conduit with reduction of the lumen to 7 mm at the distal anastomosis. Peak systolic pressure gradient between the right ventricle and the central pulmonary artery was 60 mmHg.
Angiography of the right ventricular outflow tract and subsequent cardiac magnetic resonance imaging revealed the presence of multiple aneurysms: the largest aneurysmatic formation arose from the lateral portion of the conduit with a diameter of 10 mm at the neck and a maximum size of the aneurysm of 27 × 24 mm. There was evidence of three small aneurysms in the distal right ventricular outflow tract (Fig. 1). Surgical conduit replacement was performed uneventfully: after en bloc explantation of the Matrix P® conduit and the proximal aneurysms, a 22 mm—Hancock Conduit (Medtronic, Minneapolis, MN, USA) was implanted. Both pulmonary arteries were reconstructed using a cell-free equine pericardial Matrix patch (AutoTissue, Berlin, Germany). Pathological examination of the explant proved the origin of the aneurysms to be within the Matrix conduit just below the level of the valve (Fig. 2A). There was no relation of this origin to the sutures of the proximal anastomosis. On histopathological examination, we found only few fibroblasts having colonized the conduit wall (Supplementary Figure S1). The wall of the largest aneurysm consisted almost cell-free conduit tissue without any significant inflammatory or foreign-body response (Fig. 2B).
DISCUSSION Narrowing and obstruction of the right ventricular outflow tract is the key issue in a variety of congenital heart diseases such as tetralogy of Fallot. Reconstruction of the right ventricular outflow tract often requires the implantation of a valved conduit with pulmonary homografts being considered as gold standard. However, pulmonary homografts offer a number of disadvantages such as limited availability in small sizes, lack of growth and fast deterioration in
© The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
CASE REPORT
CASE REPORT
European Journal of Cardio-Thoracic Surgery (2014) 1–3 doi:10.1093/ejcts/ezt635
2
D. Backhoff et al. / European Journal of Cardio-Thoracic Surgery
Figure 1: (A and B) anteroposterior and lateral angiograms of the right ventricular outflow tract. A large aneurysm (27 × 24 mm, arrows) with a small neck (10 mm) is evident proximal to the significant stenosis of the distal conduit anastomosis. There are three smaller aneurysms (asterisks) which are also proximal to the distal stenosis and therefore in the high-pressure region of the conduit. The right ventricular outflow tract is significantly dilated. (C and D) 3D virtual reality reconstruction of magnetic resonance imaging gadolinium angiogram of the right ventricle and the right ventricular outflow tract illustrating the findings.
infancy [1]. In our institution, we therefore use pulmonary homografts predominantly in adolescents or young adults and bioprosthetic conduits in younger patients. The introduction of decellularization of xenogenous materials into clinical practice gave hope for improved biomechanical properties, decreased immunogenicity and growth of the conduits [2, 3]. Decellularization is a special chemical process that removes all cellular elements of xenogenous tissue, leaving only a connective tissue scaffold that is colonized by the host’s cells after implantation [2]. The Matrix P® is such a decellularized porcine pulmonary conduit which was available in Europe from 2004 to 2009. The succeeding model now is
reinforced by surrounding glutaraldehyde-fixed equine pericardial patches which—serving as interposit—additionally facilitate connection. The group of the inventor published an actuarial freedom from reoperation or reintervention of 90% 4 years after implantation [2]. It is of note, however, that other centres reported notably less favourable results [4, 5]. In our patient, 5 years after implantation, we found the Matrix P® conduit to be severely obstructed at the level of the distal anastomosis, which has been identified as the major problem in other patients before [5]. The main and notable finding in our patient was the formation of multiple aneurysms of the
3
CASE REPORT
D. Backhoff et al. / European Journal of Cardio-Thoracic Surgery
Figure 2: (A) Explanted Matrix P® conduit (inferior view). The entry to the largest aneurysm (white arrows) is just below the level of the valve (asterisk). (B) Histopathological examination of the wall of the largest aneurysm (haematoxylin and eosin staining). The endocardial surface is smooth. Marker depicts the almost cell-free subentothelial layer—identified as conduit tissue. There is no prominent inflammatory or foreign-body response.
conduit below the level of the valve. Formation of pseudoaneurysms following Matrix P® implantation has been described before [4]. Conduit dissection allowing blood flow in the thickness of the conduit wall is a possible explanation for formation of pseudoaneurysms and has also been observed by Rüffer et al. [5]. In our case, histopathological examination revealed formation of true aneurysms (consisting of xenogenic conduit tissue) which has not been reported in Matrix type conduits before. Entry of the aneurysms was formed by conduit wall; failure of the sutures at the proximal anastomosis could therefore be ruled out as the underlying mechanism. A possible explanation may be that decreased colonialization of the xenogenous conduit with the patient’s fibroblast probably led to unfavourable biomechanical properties during the long-term course. In our patient, we therefore believe that aneurysm formation of the conduit was a result of fatigue of the conduit wall under suprasystemic pressure. This severe complication should be kept in mind when patients with Matrix-type conduits are attended during the long-term course.
SUPPLEMENTARY MATERIAL Supplementary material is available at EJCTS online.
Funding No external funding was secured for this study. Conflict of interest: none declared.
REFERENCES [1] Tweddell JS, Pelech AN, Frommelt PC, Mussatto KA, Wyman JD, Fedderly RT et al. Factors affecting longevity of homograft valves used in right ventricular outflow tract reconstruction for congenital heart disease. Circulation 2000;102(19 Suppl 3):III130–5. [2] Konertz W, Angeli E, Tarusinov G, Christ T, Kroll J, Dohmen P et al. Right ventricular outflow tract reconstruction with decellularized porcine xenografts in patients with congenital heart disease. J Heart Valve Dis 2011;20: 341–7. [3] Konuma T, Devaney EJ, Bove EL, Gelehrter S, Hirsch JC, Tavakkol Z et al. Performance of CryoValve SG decellularized pulmonary allografts compared with standard cryopreserved allografts. Ann Thorac Surg 2009;88: 849–54; discussion 554-5. [4] Perri G, Polito A, Esposito C, Albanese SB, Francalanci P, Pongiglione G et al. Early and late failure of tissue-engineered pulmonary valve conduits used for right ventricular outflow tract reconstruction in patients with congenital heart disease. Eur J Cardiothorac Surg 2012;41:1320–5. [5] Rüffer A, Purbojo A, Cicha I, Glöckler M, Potapov S, Dittrich S et al. Early failure of xenogenous de-cellularised pulmonary valve conduits—a word of caution! Eur J Cardiothorac Surg 2010;38:78–85.
