9th Current Trends in Aortic & Cardiovascular Surgery & Interventions Tom Treasure, MD
CME Credit Presented at the 9th Current Trends in Aortic and Cardiovascular Surgery and Interventions Conference; Houston, 26–27 April 2013. Section Editor: Joseph S. Coselli, MD Key words: Aneurysm, dissecting/complications/ surgery; aortic aneurysm, thoracic/complications; aortic root; blood vessel prosthesis, experimental; computer-aided design; dilatation, pathologic; magnetic resonance angiography; Marfan syndrome/complications/surgery; surgical mesh; tomography, X-ray computed; treatment outcome From: Clinical Operational Research Unit, University College London, London WC1H 0BT, United Kingdom Address for reprints: Tom Treasure, MD, Clinical Operational Research Unit, University College London, 4 Taviton St., London WC1H 0BT, UK E-mail: [email protected] © 2013 by the Texas Heart ® Institute, Houston
Texas Heart Institute Journal
Personalized External Aortic Root Support
T
he primary objective of aortic root surgery in Marfan syndrome is to prevent dissection at its most common site in the ascending aorta. Dissection is the greatest threat to life in this disease, and there is general clinical acceptance that expectation of longer life has improved since aortic root replacement has become widely available. Nevertheless, the underlying aortopathy means that other segments of the aorta remain at risk of dilation and dissection both in those who, through surgical intervention, have survived an acute dissection and in those who have undergone prophylactic replacement of the ascending aorta. Because present methods of root replacement are imperfect, there can, over time, be further dilation in unsupported segments and “false aneurysms” (dissections) at suture lines. However, aortic root dilation presents by far the highest risk of death and, in those who experience dissection, the aortic root is most commonly the first site. Therefore, inspection and measurement of the aortic root with cardiac ultrasound is standard care in people in whom Marfan syndrome is suspected, whether because of their clinical presentation or the presence of the syndrome in a family member. The decision to offer root replacement is dependent on the size of the aorta, on the rate of increase in size, and on whether or not there is a history of dissection among family members. This is an anxious time and a difficult decision for physicians, because if we wait too long, the patient might have an acute aortic dissection, with a high risk of death or a lost opportunity for a planned operation. On the other hand, root replacement is a serious intervention; although mortality rates are low at major cardiovascular centers, there are several inescapable hazards, whether the operation includes aortic valve replacement or conservation of the aortic valve (Table I 1). Since 2004, we have been offering a non-ablative surgical option that completely conserves the root with its morphology and the natural architecture of the aortic valve.2 The idea was proposed to the Marfan Association at its annual meeting in 2000 by Tal Golesworthy, a design engineer who himself has Marfan syndrome. Magnetic resonance or computed tomographic images of the individual’s aorta are used in a process of computer-aided design and rapid prototyping to create a unique personalized 3-dimensional replica of the aorta (Fig. 1). Upon this templet is made an accurate and close-fitting support of very soft and pliable macroporous mesh (Fig. 2). This support intimately covers the aorta from the aortoventricular junction to beyond the brachiocephalic artery, with openings to accommodate the emerging coronary and brachiocephalic arteries (Fig. 3). Since its inception, the method has been used consistently, without further modifications or design iterations. Personalized External Aortic Root Support (PEARS) must unquestionably be distinguished from so-called wrapping procedures in which a relatively stiff and unyielding vascular graft is cut and fashioned on the operating table. The PEARS technique does not require cardiopulmonary bypass, although bypass has been used occasionally as an adjunct. The aorta is not clamped or opened, so there is no myocardial ischemia involved. There is no routine requirement for blood products, nor is there risk of cerebral ischemia or embolus.3 The subsequent incorporation of the mesh by the adventia, to form a composite, is now well understood. We have confirmed the histologic appearances of that incorporation in studies in sheep.4 There is clinical precedent in which partial “girdling” of the aorta was undertaken in more than 100 patients over the course of 2 decades.5 The clinical course of these patients showed no “migration,” and the enclosed parts of the aorta remained stable (Fig. 46). Any subsequent expansion of the aorta was in Personalized External Aortic Root Support
549
unsupported segments.5 There are compelling reasons to believe that the supported portion of the aorta will not dilate. A greater length of the aorta is routinely supported in PEARS than is replaced in root replacement; because of the absence of a suture line and the presence of graduated support, the adjacent aorta distal to that support is less likely subject to stress.
Fig. 1 Photograph shows individual patients’ ascending aortic formers, created by computer-aided design and rapid prototyping. The variation in size and shape illustrates the advantages of the personalized approach to manufacture. Reprinted from Pepper J, et al.2 Copyright 2013, with permission from Oxford University Press.
Two fears frequently raised when we present our work on PEARS are that the mesh might migrate and impinge on the coronary arteries and that dissection might still occur within the supported section. We believe that the first can be discounted. It stems from anecdotal accounts consequent to off-label use of vascular-graft material. The soft nature of the mesh used in PEARS, and its histologically confirmed incorporation, preclude this eventuality. Migration was never seen over the 20 years of aortic girdling in which a very similar material was used.5 Although dissection could in theory occur, the major determinant of dissection is aortic size, and this is completely controlled in PEARS. Moreover, such dissection would much less likely be life-threatening. Any surgical revision is probably much easier in a meshincorporated aorta than in the patient’s fragile native Marfan aorta. In over 150 patient-years of follow-up, there have been no untoward events related to the aortic wall or valve after PEARS. When compared with the data for either the Bentall procedure or valve-sparing root replacement (Table I),1 outcomes so far are very favorable for external support. It should be remembered that root replacement is performed in young people, half of whom are under 30 years of age and might realistically hope for 50 or more years of life. Even though event rates after valve-
Fig. 3 Artist’s drawing depicts the mesh on the aorta extending from proximal to the coronary arteries to the arch of the aorta distal to the brachiocephalic artery.
Fig. 2 Photograph shows the macroporous pliant mesh fabric used to make the personalized support for the individual recipient’s aorta.
550
Personalized External Aortic Root Support
Reprinted from Pepper J, et al.2 Copyright 2013, with permission from Oxford University Press. BCA = brachiocephalic artery; LCA = left coronary artery; RCA = right coronary artery
Volume 40, Number 5, 2013
sparing root replacement appear to be low, they become more likely than not over this period of time. To be spared valve-related events would be of great benefit to these patients.
A
The device has undergone Health Technology Appraisal by the United Kingdom’s National Institute for Health and Clinical Excellence and is available for patients enrolled in the National Health Service in Britain.7
B
Fig. 4 Pseudosaggital magnetic resonance images show a patient’s Marfan aorta A) before and B) 8 years after personalized aortic root support. Magnetic resonance or computed tomographic files can be used for computer-aided modeling. This patient’s aortic root has remained the same size and shape after more than 8 years. Figure 4A appeared in Golesworthy T, et al.6 Copyright 2004, with permission from Elsevier.
TABLE I. Personalized External Aortic Root Support: Comparative Evaluation Total Root PEARS Replacement* Variable (n=30) (n=972)
Valve-Sparing Root Replacement* (n=413)
Preoperative Patient Characteristics 31 ± 12
35 ± 0.5
33 ± 0.64
Preoperative aortic root diameter, mm
46.2 ± 3.4
61 ± 0.7
52 ± 0.3
Proportion of patients with dissection
—
0.3 ± 0.01
0.18 ± 0.02
Early mortality rate, %
—
4.1 (1.9–7.7)
3.2 (0.5–17.9)
Reinterventions on aortic valve, % per yr
—
0.3 (0.1–0.5)
1.3 (0.3–2.2)
Thromboembolic events, % per yr
—
0.7 (0.5–0.9)
0.3 (0.1–0.6)
Endocarditis, % per yr
—
0.3 (0.2–0.5)
0.2 (0–0.3)
Composite valve-related events, % per yr
—
1.3 (0.6–2.0)
1.9 (0.8–2.9)
Patient age, yr
Postoperative and Late Outcomes
PEARS = personalized external aortic root support *From: Benedetto U, et al.1 Data are presented as mean ± SD or as percentage and 95% confidence interval.
Texas Heart Institute Journal
Personalized External Aortic Root Support
551
Acknowledgments The author thanks the PEARS project team: Tal Golesworthy, Raad Mohiaddin, John Pepper, Mario Petrou, Filip Rega, Ulrich Rosendahl, and Michael Rubens. This project was supported by the NIHR Cardiovascular Biomedical Research Unit of Royal Brompton Hospital (London, UK) and Harefield NHS Foundation Trust and Imperial College London. The operations described herein were performed at Royal Brompton Hospital (London), University Hospital (Leuven, Belgium), and John Radcliffe Hospital (Oxford, UK).
References 1. Benedetto U, Melina G, Takkenberg JJ, Roscitano A, Angeloni E, Sinatra R. Surgical management of aortic root disease in Marfan syndrome: a systematic review and meta-analysis. Heart 2011;97(12):955-8. 2. Pepper J, Petrou M, Rega F, Rosendahl U, Golesworthy T, Treasure T. Implantation of an individually computer-designed and manufactured external support for the Marfan aortic root. Available from: http://mmcts.oxfordjournals.org/ content/2013/mmt004.full [2013 Mar 20; cited 2013 Aug 23]. 3. Treasure T, Crowe S, Chan KM, Ranasinghe A, Attia R, Lees B, et al. A method for early evaluation of a recently introduced technology by deriving a comparative group from existing clinical data: a case study in external support of the Marfan aortic root. BMJ Open 2012;2(2):e000725. 4. Verbrugghe P, Verbeken E, Pepper J, Treasure T, Meyns B, Meuris B, et al. External aortic root support: a histological and mechanical study in sheep. Interact Cardiovasc Thorac Surg 2013;17(2):334-9. 5. Cohen O, Odim J, De la Zerda D, Ukatu C, Vyas R, Vyas N, et al. Long-term experience of girdling the ascending aorta with Dacron mesh as definitive treatment for aneurysmal dilation. Ann Thorac Surg 2007;83(2):S780-90. 6. Golesworthy T, Lamperth M, Mohiaddin R, Pepper J, Thornton W, Treasure T. The Tailor of Gloucester: a jacket for the Marfan’s aorta. Lancet 2004;364(9445):1582. 7. Treasure T, Pepper J, Golesworthy T, Mohiaddin R, Anderson RH. External aortic root support: NICE guidance. Heart 2012;98(1):65-8.
552
Personalized External Aortic Root Support
Volume 40, Number 5, 2013
CME Credit Presented at the 9th Current Trends in Aortic and Cardiovascular Surgery and Interventions Conference; Houston, 26–27 April 2013. Section Editor: Joseph S. Coselli, MD Key words: Aneurysm, dissecting/complications/ surgery; aortic aneurysm, thoracic/complications; aortic root; blood vessel prosthesis, experimental; computer-aided design; dilatation, pathologic; magnetic resonance angiography; Marfan syndrome/complications/surgery; surgical mesh; tomography, X-ray computed; treatment outcome From: Clinical Operational Research Unit, University College London, London WC1H 0BT, United Kingdom Address for reprints: Tom Treasure, MD, Clinical Operational Research Unit, University College London, 4 Taviton St., London WC1H 0BT, UK E-mail: [email protected] © 2013 by the Texas Heart ® Institute, Houston
Texas Heart Institute Journal
Personalized External Aortic Root Support
T
he primary objective of aortic root surgery in Marfan syndrome is to prevent dissection at its most common site in the ascending aorta. Dissection is the greatest threat to life in this disease, and there is general clinical acceptance that expectation of longer life has improved since aortic root replacement has become widely available. Nevertheless, the underlying aortopathy means that other segments of the aorta remain at risk of dilation and dissection both in those who, through surgical intervention, have survived an acute dissection and in those who have undergone prophylactic replacement of the ascending aorta. Because present methods of root replacement are imperfect, there can, over time, be further dilation in unsupported segments and “false aneurysms” (dissections) at suture lines. However, aortic root dilation presents by far the highest risk of death and, in those who experience dissection, the aortic root is most commonly the first site. Therefore, inspection and measurement of the aortic root with cardiac ultrasound is standard care in people in whom Marfan syndrome is suspected, whether because of their clinical presentation or the presence of the syndrome in a family member. The decision to offer root replacement is dependent on the size of the aorta, on the rate of increase in size, and on whether or not there is a history of dissection among family members. This is an anxious time and a difficult decision for physicians, because if we wait too long, the patient might have an acute aortic dissection, with a high risk of death or a lost opportunity for a planned operation. On the other hand, root replacement is a serious intervention; although mortality rates are low at major cardiovascular centers, there are several inescapable hazards, whether the operation includes aortic valve replacement or conservation of the aortic valve (Table I 1). Since 2004, we have been offering a non-ablative surgical option that completely conserves the root with its morphology and the natural architecture of the aortic valve.2 The idea was proposed to the Marfan Association at its annual meeting in 2000 by Tal Golesworthy, a design engineer who himself has Marfan syndrome. Magnetic resonance or computed tomographic images of the individual’s aorta are used in a process of computer-aided design and rapid prototyping to create a unique personalized 3-dimensional replica of the aorta (Fig. 1). Upon this templet is made an accurate and close-fitting support of very soft and pliable macroporous mesh (Fig. 2). This support intimately covers the aorta from the aortoventricular junction to beyond the brachiocephalic artery, with openings to accommodate the emerging coronary and brachiocephalic arteries (Fig. 3). Since its inception, the method has been used consistently, without further modifications or design iterations. Personalized External Aortic Root Support (PEARS) must unquestionably be distinguished from so-called wrapping procedures in which a relatively stiff and unyielding vascular graft is cut and fashioned on the operating table. The PEARS technique does not require cardiopulmonary bypass, although bypass has been used occasionally as an adjunct. The aorta is not clamped or opened, so there is no myocardial ischemia involved. There is no routine requirement for blood products, nor is there risk of cerebral ischemia or embolus.3 The subsequent incorporation of the mesh by the adventia, to form a composite, is now well understood. We have confirmed the histologic appearances of that incorporation in studies in sheep.4 There is clinical precedent in which partial “girdling” of the aorta was undertaken in more than 100 patients over the course of 2 decades.5 The clinical course of these patients showed no “migration,” and the enclosed parts of the aorta remained stable (Fig. 46). Any subsequent expansion of the aorta was in Personalized External Aortic Root Support
549
unsupported segments.5 There are compelling reasons to believe that the supported portion of the aorta will not dilate. A greater length of the aorta is routinely supported in PEARS than is replaced in root replacement; because of the absence of a suture line and the presence of graduated support, the adjacent aorta distal to that support is less likely subject to stress.
Fig. 1 Photograph shows individual patients’ ascending aortic formers, created by computer-aided design and rapid prototyping. The variation in size and shape illustrates the advantages of the personalized approach to manufacture. Reprinted from Pepper J, et al.2 Copyright 2013, with permission from Oxford University Press.
Two fears frequently raised when we present our work on PEARS are that the mesh might migrate and impinge on the coronary arteries and that dissection might still occur within the supported section. We believe that the first can be discounted. It stems from anecdotal accounts consequent to off-label use of vascular-graft material. The soft nature of the mesh used in PEARS, and its histologically confirmed incorporation, preclude this eventuality. Migration was never seen over the 20 years of aortic girdling in which a very similar material was used.5 Although dissection could in theory occur, the major determinant of dissection is aortic size, and this is completely controlled in PEARS. Moreover, such dissection would much less likely be life-threatening. Any surgical revision is probably much easier in a meshincorporated aorta than in the patient’s fragile native Marfan aorta. In over 150 patient-years of follow-up, there have been no untoward events related to the aortic wall or valve after PEARS. When compared with the data for either the Bentall procedure or valve-sparing root replacement (Table I),1 outcomes so far are very favorable for external support. It should be remembered that root replacement is performed in young people, half of whom are under 30 years of age and might realistically hope for 50 or more years of life. Even though event rates after valve-
Fig. 3 Artist’s drawing depicts the mesh on the aorta extending from proximal to the coronary arteries to the arch of the aorta distal to the brachiocephalic artery.
Fig. 2 Photograph shows the macroporous pliant mesh fabric used to make the personalized support for the individual recipient’s aorta.
550
Personalized External Aortic Root Support
Reprinted from Pepper J, et al.2 Copyright 2013, with permission from Oxford University Press. BCA = brachiocephalic artery; LCA = left coronary artery; RCA = right coronary artery
Volume 40, Number 5, 2013
sparing root replacement appear to be low, they become more likely than not over this period of time. To be spared valve-related events would be of great benefit to these patients.
A
The device has undergone Health Technology Appraisal by the United Kingdom’s National Institute for Health and Clinical Excellence and is available for patients enrolled in the National Health Service in Britain.7
B
Fig. 4 Pseudosaggital magnetic resonance images show a patient’s Marfan aorta A) before and B) 8 years after personalized aortic root support. Magnetic resonance or computed tomographic files can be used for computer-aided modeling. This patient’s aortic root has remained the same size and shape after more than 8 years. Figure 4A appeared in Golesworthy T, et al.6 Copyright 2004, with permission from Elsevier.
TABLE I. Personalized External Aortic Root Support: Comparative Evaluation Total Root PEARS Replacement* Variable (n=30) (n=972)
Valve-Sparing Root Replacement* (n=413)
Preoperative Patient Characteristics 31 ± 12
35 ± 0.5
33 ± 0.64
Preoperative aortic root diameter, mm
46.2 ± 3.4
61 ± 0.7
52 ± 0.3
Proportion of patients with dissection
—
0.3 ± 0.01
0.18 ± 0.02
Early mortality rate, %
—
4.1 (1.9–7.7)
3.2 (0.5–17.9)
Reinterventions on aortic valve, % per yr
—
0.3 (0.1–0.5)
1.3 (0.3–2.2)
Thromboembolic events, % per yr
—
0.7 (0.5–0.9)
0.3 (0.1–0.6)
Endocarditis, % per yr
—
0.3 (0.2–0.5)
0.2 (0–0.3)
Composite valve-related events, % per yr
—
1.3 (0.6–2.0)
1.9 (0.8–2.9)
Patient age, yr
Postoperative and Late Outcomes
PEARS = personalized external aortic root support *From: Benedetto U, et al.1 Data are presented as mean ± SD or as percentage and 95% confidence interval.
Texas Heart Institute Journal
Personalized External Aortic Root Support
551
Acknowledgments The author thanks the PEARS project team: Tal Golesworthy, Raad Mohiaddin, John Pepper, Mario Petrou, Filip Rega, Ulrich Rosendahl, and Michael Rubens. This project was supported by the NIHR Cardiovascular Biomedical Research Unit of Royal Brompton Hospital (London, UK) and Harefield NHS Foundation Trust and Imperial College London. The operations described herein were performed at Royal Brompton Hospital (London), University Hospital (Leuven, Belgium), and John Radcliffe Hospital (Oxford, UK).
References 1. Benedetto U, Melina G, Takkenberg JJ, Roscitano A, Angeloni E, Sinatra R. Surgical management of aortic root disease in Marfan syndrome: a systematic review and meta-analysis. Heart 2011;97(12):955-8. 2. Pepper J, Petrou M, Rega F, Rosendahl U, Golesworthy T, Treasure T. Implantation of an individually computer-designed and manufactured external support for the Marfan aortic root. Available from: http://mmcts.oxfordjournals.org/ content/2013/mmt004.full [2013 Mar 20; cited 2013 Aug 23]. 3. Treasure T, Crowe S, Chan KM, Ranasinghe A, Attia R, Lees B, et al. A method for early evaluation of a recently introduced technology by deriving a comparative group from existing clinical data: a case study in external support of the Marfan aortic root. BMJ Open 2012;2(2):e000725. 4. Verbrugghe P, Verbeken E, Pepper J, Treasure T, Meyns B, Meuris B, et al. External aortic root support: a histological and mechanical study in sheep. Interact Cardiovasc Thorac Surg 2013;17(2):334-9. 5. Cohen O, Odim J, De la Zerda D, Ukatu C, Vyas R, Vyas N, et al. Long-term experience of girdling the ascending aorta with Dacron mesh as definitive treatment for aneurysmal dilation. Ann Thorac Surg 2007;83(2):S780-90. 6. Golesworthy T, Lamperth M, Mohiaddin R, Pepper J, Thornton W, Treasure T. The Tailor of Gloucester: a jacket for the Marfan’s aorta. Lancet 2004;364(9445):1582. 7. Treasure T, Pepper J, Golesworthy T, Mohiaddin R, Anderson RH. External aortic root support: NICE guidance. Heart 2012;98(1):65-8.
552
Personalized External Aortic Root Support
Volume 40, Number 5, 2013
