Asian Cardiovasc Thorac Ann 2008;16:355-360
© 2008 Asia Publishing EXchange Ltd
Subcoronary Implantation of a Stentless Valve in Patients with Aortic Aneurysms
Alexander John, MD,
Basel Al-Hariri, MD,
Juergen Ackemann, MD,
Mohamed El-Mehsen, MD,
Stefan Roethemeyer, MD,
Henning Warnecke, PhD
Schuechtermann Clinic, Bad Rothenfelde, Germany
For reprint information contact: Alexander John, MD, Tel: 49 542 464 1651, Fax: 49 542 464 1653, Email: ajohn{at}schuechtermann-klinik.de, Department of Cardiac Surgery, Schuechtermann Klinik, Ulmenallee 11, 49214 Bad Rothenfelde, Germany.
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ABSTRACT
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Experience with a new operation for patients with aortic valve disease and aneurysm or dissection of the ascending aorta is described. Twenty-four patients aged 66 87 years were operated on using a subcoronary implantation technique with a stentless aortic valve bioprosthesis and an extension using a vascular tube prosthesis. No major adverse cardiac events were observed in the postoperative period. This operation offers a safe alternative to the technically more demanding procedures of composite bioprosthetic ascending aortic replacement or full root replacement.
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INTRODUCTION
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Aortic valve disease associated with an ascending aortic aneurysm is conventionally treated by composite graft replacement with reimplantation of the coronary ostia.1 Both diseases are caused by degenerative changes associated with old age. Biological valves are preferred in elderly patients. Stentless valves are usually implanted by the full root method, with reimplantation of the mobilized coronary ostia, because the subcoronary technique of valve replacement is thought to induce disturbance of commissural geometry and lead to incompetence in the presence of aortic dilatation. However, coronary reimplantation is technically difficult in elderly patients with a friable or calcified aortic wall. Bleeding from the unprotected and inaccessible anastomoses can lead to considerable morbidity and mortality.2 Simplicity and speed are especially important in this group of patients. We aimed to avoid unprotected coronary ostial anastomoses and to modify the standard subcoronary implantation technique for the Freestyle stentless bioprosthesis (Medtronic, Inc., Minneapolis, MN, USA) so as to correct aneurysmal aortic dilatation while preserving commissural geometry and the valvular competence of the graft. A suitably sized vascular tube prosthesis was used to replace the rest of the ascending aortic aneurysm up to the arch.
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PATIENTS AND METHODS
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Between June 2003 and November 2005, 24 patients were operated on with a diagnosis of severe aortic valve disease and aneurysm of the proximal aorta (Table 1
). When the diameter of the aorta was 
4.5 cm, it was considered aneurysmal. Aortic diameter was measured echocardiographically at different levels between the annulus and the beginning of the arch (Table 2). Most patients had massively dilated aortas. Maximum dilatation was seen beyond the sinotubular junction, in the middle of the ascending aorta. As a rule, biological valves are recommended for patients 70 years old. Some younger patients in whom anticoagulants were undesirable also received biological valves. All had a catheter study and coronary angiography, and were operated on electively, except for 2 patients: one with acute dissection of the proximal aorta, and another in acute left ventricular failure. The patient with type A dissection, who was in cardiogenic shock, had alcohol ablation of a hypertrophic septal obstruction 6 years earlier. He had known calcified aortic stenosis and incompetence. Nine patients had additional coronary stenoses requiring bypass grafts. One 68-year-old man had a degenerated porcine valve that had been implanted 25 years earlier. Another with a valve implanted 19 years earlier, had recent hemiplegia probably caused by a septic embolus as the valve was found to be infected and thrombosed.
The Freestyle bioprosthesis was implanted using a modification of the standard "cylinder within a cylinder" subcoronary implantation method described by Westaby and colleagues.3 We have further modified and standardized this procedure.4 The aneurysmally dilated aortic root is more conical than cylindrical, and our method converts it back to a cylinder to avoid dead space between the aorta and the porcine valve. Arterial cannulation was carried out on the aortic arch in all patients. Retrograde blood cardioplegia via the coronary sinus was used routinely. Distal anastomoses of coronary bypass grafts were performed first. The aorta was incised transversely 1 cm above the sinotubular junction. A valve that was one size larger than the aortic annulus was implanted using 5 or 6 simple interrupted Ethibond sutures in each sinus. Two double-armed 4/0 Prolene sutures were used for the second subcoronary suture row. Each began under the coronary ostium and proceeded to the left commissure. The other ends of the sutures proceeded around the corresponding ostium towards the aortotomy edge so that the outflow of the porcine valve remained the same size as before scalloping. Thus the scalloped portions of the graft were filled by an equal-sized segment of aorta (Figure 1). Using a running suture, the massively dilated aorta was plicated to the anterolateral non-scalloped free edge of the porcine valve, reducing it to the size of the porcine aorta (Figure 2). The plication was maximal on the lateral aspect above the non-scalloped porcine sinus. After valve implantation, the aortotomy was extended posteriorly, resulting in complete transection of the aorta. A polyester vascular prosthesis (Vascutek Gelweave; Terumo Ltd., Renfrewshire, Scotland, UK), usually one size larger than the valve, was anastomosed to the new combined human-porcine aorta using 3/0 or 4/0 Prolene with a strip of Teflon on the outer aspect (Figure 3). The anastomosis distal to the post-aneurysmal aorta was performed using 3/0 Prolene and a strip of Teflon. This was followed by de-airing and release of the aortic cross clamp. Proximal anastomoses of the coronary grafts were undertaken on the beating heart. All operations were carried out under normothermia, except in the patient with acute dissection who was cooled down to 26°C rectal temperature, and underwent circulatory arrest and retrograde cerebral perfusion for 12 min to accomplish the distal anastomosis between the vascular prosthesis and the aortic arch. Wherever possible, the aneurysmal wall was loosely approximated around the new prosthetic aorta.
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Figure 3. View from the side. The porcine valve is implanted by the subcoronary method and end-to-end anastomoses of the vascular prosthesis follows at the lower and upper ends.
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RESULTS
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There was no early mortality. Operative data are given in Table 3. Nine patients did not need a blood transfusion. Pericardial effusion had to be drained postoperatively in 3 patients. Postoperative echocardiography confirmed proper functioning of the implanted valve and normal dimensions of the new ascending aorta (Table 4). One 73-year-old lady with severe coronary artery disease, who had 3 bypass grafts, suffered an anterior myocardial infarction postoperatively and required a tracheostomy and prolonged ventilation, resulting in a hospital stay of 6 months. She has periods of depression but is otherwise in good health. There were 2 late deaths, after 6 months and after 2 years, both from noncardiac causes: an 87-year-old patient died from lung infection and sepsis, and an 83-year-old man had a major cerebral hemorrhage from which he did not recover. All others, including the patient with acute dissection, recovered well and continue to enjoy good health.
All patients were contacted to undergo follow-up echocardiography. One 80-year-old lady could not come to the examination but reported that she was happy and doing well. The other 21 patients were examined after 16 ± 7 months. Clinically, all were doing well, and all were in sinus rhythm except for 2 who were in atrial fibrillation. Four patients had trivial incompetence, paravalvular in 1 and transvalvular in 3; the other 17 had no aortic incompetence. Cardiac function was good and the gradients were low (Table 5). Generally, the larger the valve, the smaller the gradient. Four patients who received 23- or 25-mm valves and had a vascular prosthesis that was 3 mm larger than the valve, also had competent valves. As the aortotomy was fixed by the Teflon-supported continuous suture, anastomosis of the aorta to a larger prosthesis did not cause early or late incompetence. The 2 patients in atrial fibrillation take oral anticoagulants, but all others are free of any valve-related medication. Patients with coronary bypass grafts continue to take aspirin. Figures 4 and 5 show the preoperative and postoperative magnetic resonance images of a representative patient.
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Figure 4. Preoperative magnetic resonance image of a 75-year-old man with a calcified aortic valve and an ascending aortic aneurysm measuring 63 mm. He had combined aortic stenosis and incompetence.
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Figure 5. The same patient after the operation. He received a 29-mm Freestyle bioprosthesis and a 30-mm polyester vascular prosthesis.
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DISCUSSION
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Aortic dilatation in patients with aortic aneurysms is usually most pronounced in the sinotubular junction and beyond. It is also asymmetrical, with the convex anterolateral aspect more dilated than the concavity.5 The noncoronary sinus is most dilated, and the left coronary sinus is least dilated. Unless the annulus is dilated beyond 29 mm, it is possible to implant a suitably sized stentless valve and attach the valve commissures to the patient’s aortic wall at distances exactly corresponding to the original dimensions of the porcine valve, and also avoid the coronary ostia.
There are various ways to replace a degenerated and diseased aortic root in an elderly patient. One is to implant the valve in full root style and use an additional vascular prosthesis to replace the dilated ascending aorta. This procedure is rather extensive, needs longer perfusion and cross clamp times, leaves several unprotected anastomoses, and may involve major blood loss that can lead to considerable perioperative problems in elderly patients. Significantly higher operative mortality has been reported in patients subjected to the full root technique.6,7 Valve-bearing conduits incorporating mechanical or biological valves have the same problems. In one large series of younger patients (mean age, 48 ± 14 years), 24% mortality was reported in those who needed reexploration for bleeding.8 Our patients were much older, and the method described herein is a safe alternative in this high-risk group. The combined human-porcine aorta provides a good buttress on which to suture the vascular prosthesis, unlike in the full root method.
As experience with stentless valves increases, more advantages are being appreciated.9 Extended indications have been reported and include patients with bacterial endocarditis, prosthetic valve endocarditis, poor left ventricular function, and small aortic roots.10 The stentless technology allows larger valves to be implanted, resulting in lower gradients and faster recovery. To our knowledge, this is the first report of successful use of a stentless valve in the subcoronary position in patients with aneurysm or dissection of the ascending aorta. Older patients have limited reserves and any operation on them must be short and involve minimal blood loss. Our method avoids implantation of the coronaries which in elderly patients are often sclerosed, calcified, fragile, and thinned out, with the potential to cause troublesome bleeding. The only unsupported portion of the proximal aorta that is retained is where it fills the scalloped areas, but even here it is partly supported by the external Teflon strip, thus considerably reducing the potential for bleeding and future dilatation.
Older patients with aortic valve disease and an aneurysmally dilated or dissected aorta can be successfully treated by this method using subcoronary implantation of the Medtronic Freestyle stentless bioprosthesis with an extension using a suitably sized vascular tube prosthesis.
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ACKNOWLEDGMENTS
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We thank Mr Dieter Goerbing and Mr Joel Chechik for preparation of the illustrations.
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Footnotes
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ADDENDUM
After submitting this paper we have done an additional 31 such operations taking the total to 55. There has been no operative mortality and the results continue to be good.
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REFERENCES
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ABSTRACT
INTRODUCTION
