Asian Cardiovasc Thorac Ann 2005;13:53-57
© 2005 Asia Publishing EXchange Ltd
Modified versus Standard Mechanical Valved Aortic Conduit
Paul P Urbanski, MD,
Witold Dinstak, MD,
Stefan Frank, MD,
Alexander Siebel, MD,
Robert W Hacker, MD
Department of Cardiovascular Surgery, Cardiovascular Clinic, Bad Neustadt, Germany
For reprint information contact: Paul P Urbanski, MD Tel: 49 97 7166 2416 Fax: 49 97 7165 1219 Email: p.urbanski{at}herzchirurgie.de, Herz- und Gefaess-Klinik, Salzburger Leite 1, Bad Neustadt 97616, Germany.
 |
ABSTRACT
|
|---|
The aim of this study was to compare the hemodynamic characteristics and early clinical results of a commercially available standard aortic conduit with those of a modified valved composite graft, which consists of a mechanical valve prosthesis sewn into a vascular tube and placed in a supraannular position. The modified conduit was placed in 40 patients (group 1) and the standard conduit in another 40 patients (group 2). The early postoperative mortality rates (within 30 days after surgery) were 0% in group 1 and 5% (2 patients) in group 2; the difference was not statistically significant. The mean geometric orifice area of the valve prosthesis was significantly larger in group 1 than in group 2 (3.7 ± 0.7 cm2 versus 2.9 ± 0.5 cm2). Early results showed a hemodynamic advantage of the modified conduit, with significantly lower transvalvular gradients.
|
INTRODUCTION
|
|---|
A self-assembled modified composite graft with a mechanical valve was introduced at our hospital in 2000 for aortic root replacement in patients with concomitant diseases of the aortic valve and the ascending aorta as well as a small aortic annulus.1 In this conduit, the valve prosthesis is placed within a Dacron tube leaving a 5 mm margin below the valve that is sutured to the annulus, thus allowing the use of a valve prosthesis that is larger than the size of the annulus. The aim of this study was to compare the early clinical results and hemodynamic characteristics of this self-assembled graft with those of a commercially available standard conduit.
|
PATIENTS AND METHODS
|
|---|
Between November 1998 and July 2001, a total of 80 patients underwent replacement of the aortic valve and the ascending aorta using a composite graft with a mechanical valve prosthesis at our hospital. Forty patients (group 1) operated on between August 2000 and July 2001 received a self-assembled modified valved conduit. The other 40 patients (group 2), operated on in the preceding period between November 1998 and July 2000, received a commercially available standard conduit. All the operations were performed by the same surgeon (PPU). The preoperative patient characteristics were not significantly different between the groups (Table 1
).
All patients had echocardiographic examination preoperatively and before hospital discharge. Preoperative cardiac catheterization was performed in all except those patients with acute aortic dissection. Computed tomography or magnetic resonance imaging was performed in some cases to verify the pathology of the aorta. Table 2 summarizes the pathology of the aortic valve and the ascending aorta. The most frequent indication for surgery was a true aneurysm of the ascending aorta (85.0% and 92.5% in the respective groups). The other cases were for aortic dissection.
In all patients, a modified Bentall technique was employed, with resection of the aortic wall and excision of the coronary ostia as buttons. There was no significant difference between the groups with regard to the administration of anesthesia, myocardial protection with cold crystalloid cardioplegia, and the use of deep hypothermic circulatory arrest for distal aortic repair. However, femoral arterial cannulation for cardiopulmonary bypass was more frequent in group 1 because of a higher number of extended aortic repairs or aortic dissections.
The technique for aortic root replacement with the modified graft (group 1) has been described previously.1 In brief; the conduit was assembled during surgery using a collagen-coated woven polyester vascular graft (InterGard; InterVascular, La Ciotat, France) and a mechanical valve prosthesis with improved hemodynamic performance. Prostheses employed included a St. Jude HP or St. Jude Regent prosthesis (St. Jude Medical, St. Paul, MN, USA) in 31 patients and an ATS AP prosthesis (ATS Medical, Minneapolis, MN, USA) in 9 patients. All 3 valve prostheses are well suited for supraannular positioning in the conduit. They are comparable in terms of their diameter and geometric orifice area and belong to a new generation of prostheses. With a smaller sewing rim, they are better suited for incorporation into the vascular tube graft than are standard valve prostheses. The valve was placed within and attached to the tube graft approximately 5 mm above the proximal end of the tube with a continuous 4/0 polypropylene mattress suture. The conduit was then anastomosed to the annulus with interrupted pledgeted mattress sutures of 3/0 or 2/0 braided polyester using a supraannular technique, passing the sutures through the aortic annulus from the ventricular side and through the rim of the tube graft rather than through the sewing cuff of the prosthetic valve. By averting the end of the tube graft while tying the sutures, the valve prosthesis was positioned directly above the annulus. The size of the valve prosthesis was therefore defined not by the diameter of the annulus but by the size of the vascular tube (Figure 1).
View larger version (30K):
[in this window]
[in a new window]
|
Figure 1. The valve prosthesis is sewn into the vascular graft, which is anastomosed to the aortic annulus. Reprinted from Urbanski PP, Complete aortic root replacement in patients with small aortic annulus,
Ann Thorac Surg 2002;73:725–8[Abstract/Free Full Text]. With permission from the Society of Thoracic Surgeons.
|
|
In group 2, a commercially available standard conduit (CarboSeal; Sulzer CarboMedics, Austin, TX, USA) was inserted into the annulus. To attach the conduit to the annulus, interrupted pledgeted mattress sutures of 2/0 braided polyester were passed through the aortic annulus from the ventricular (n = 21) or the aortic side (n = 19) and through the suturing cuff of the valve prosthesis.
The rest of the operation was identical in all patients. The graft was fenestrated and the coronary ostial buttons reimplanted. Finally, distal anastomosis to the aorta was completed. Distal aortic repair was performed under hypothermic circulatory arrest in 16 patients of group 1 (40.0%) and 13 of group 2 (32.5%). There were 13 concomitant procedures in group 1 (32.5%) and 8 in group 2 (20.0%). The operative data are shown in Table 3.
Values are expressed as mean ± standard deviation, and statistical analyses were performed using SPSS software (SPSS, Inc., Chicago, IL, USA). Continuous data of the 2 groups were compared by the t test or, if necessary, the Mann-Whitney U test. Categorical variables were tested by the chi-squared test, with Fisher’s exact test used for variables with very low incidence. Statistical significance is defined as p < 0.05.
|
RESULTS
|
|---|
The overall in-hospital and 30-day mortality was 2.5% (2 patients). Both patients received a standard composite graft. One patient died from pulmonary bleeding on the 6th postoperative day. The other patient suffered from postoperative pulmonary and renal failure and died from pericardial tamponade on the 8th postoperative day. At autopsy, no aortic bleeding source could be found. Blood transfusion requirements were slightly, but not significantly, lower in group 1 with 1.1 ± 1.3 units versus 1.2 ± 1.7 units of packed red cells per patient.
Two patients in each group underwent a second thoracotomy to stop bleeding. While the bleeding in both group 2 patients originated from the anastomosis between the conduit and the aortic annulus, the bleeding in both group 1 patients was caused by coagulopathy and was not associated with the anastomoses. Pericardial effusion had to be evacuated in 2 patients of group 1 and 3 patients of group 2, while pulmonary failure requiring tracheostomy developed in 1 patient of group 1 and 3 patients of group 2. Neurological complications were not seen in either group.
The use of valve prostheses with improved hemodynamics in the modified grafts in combination with supraannular implantation resulted in a larger geometric orifice area in the patients of group 1 (3.7 ± 0.7 cm2 versus 2.9 ± 0.5 cm2; p < 0.01). The diameter of the annulus, as measured intraoperatively, was slightly but nonsignificantly smaller in this group (23.7 ± 2.2 mm versus 24.3 ± 1.6 mm). Echocardiographic examination before hospital discharge showed a tendency towards lower gradients across the valve in group 1. Transvalvular peak and mean gradients in the 40 surviving patients of group 1 were 20.6 ± 7.0 mm Hg and 11.6 ± 4.3 mm Hg, respectively, compared to 24.9 ± 8.4 mm Hg and 14.8 ± 5.5 mm Hg in the 38 survivors of group 2 ( p < 0.02 and p = 0.005, respectively). None of the patients in group 1 showed signs of regurgitation between the sewing ring of the valve prosthesis and the wall of the tube graft. The gradient difference between groups was even more pronounced in patients with a small annulus. Table 4 shows that in patients with an aortic annulus diameter equal or less than 23 mm, the use of a valve prosthesis with a larger geometric orifice area resulted in significantly lower postoperative peak and mean gradients than when a standard prosthesis was used.
|
DISCUSSION
|
|---|
Most modifications of the original method for replacement of the aortic valve and the ascending aorta described in 1968 by Bentall and De Bono,2 such as those proposed by Kouchoukos3 and Cabrol,4 were aimed at improving hemostasis. The Kouchoukos modification consists of excising the coronary ostia from the aortic wall as buttons and implanting them onto the conduit. The modification described by Cabrol consists of inserting a second tube graft between the 2 coronary ostia left in situ, which is anastomosed side to side to the conduit, as in his method the valve prosthesis is placed approximately 2 cm away from the end of the composite graft. The Cabrol technique is useful in cases where the ostia are difficult to access, as is sometimes seen in re-operations. The additional graft, however, increases the risk of potential late complications.5 Nowadays, the button technique of Kouchoukos is the most widely accepted method.6–8 With our modified conduit, the technique can be used without incident, since the valve prosthesis is located just above the aortic annulus.
In an attempt to improve hemostasis, various modifications of the operative technique have been developed.9–12 The application of biological glue at the rigid and uncoated suture rim of the composite graft is an efficient method, but it may cause problems due to the proximity of the coronary ostia.13–16 The anastomosis between the aortic annulus and the flexible rim of the presealed Dacron tube of our composite graft offers good hemostasis and avoids the need for additional hemostatic measures, such as incorporating a strip of felt into the suture line or applying biological glue to help seal the uncoated suture cuff when using a standard conduit. In our experience with the modified composite graft, glue was used in only 3 patients, who had acute aortic dissection, for repair of the distal aorta.
In patients who have prior aortic valve replacement, the flexible rim of the modified graft should offer a particular advantage in re-operations, after extensive decalcification of the annulus, in cases with simultaneous mitral valve replacement and in the presence of acute endocarditis. A similar approach was taken with the flanged technique recently described by Yakut,17 which is also based on moving the valve prosthesis into the graft.
Another important advantage of the modified graft is the supraannular positioning of the valve prosthesis, which allows the use of valve prostheses larger than the aortic annulus, thereby improving hemodynamics, especially in patients with a small annulus, and may eventually improve long-term results.18–20 Although there is no evidence yet that the lower transvalvular gradients seen in group 1 patients will improve long-term survival, we expect that the use of valve prostheses up to 2 sizes larger than those of standard conduits will be beneficial, especially for young and active patients and patients with a small aortic annulus. The benefit of our modified conduit on hemodynamics can be illustrated by an example. Instead of implanting a 21 mm standard valve prosthesis into an annulus 21 mm in diameter, a conduit with a size 23 prosthesis with improved hemodynamic performance can be used with the geometric orifice area of a 25 mm standard prosthesis. This avoids the need for annuloplasty, even with annuli below 21 mm in diameter.1
The incorporation of the valve prosthesis into the tube graft is a simple surgical procedure, taking only a few minutes. The difference in crossclamp time between our 2 groups was mainly due to the higher number of concomitant procedures in group 1.
The use of the modified graft also offers an economic advantage. Based on market prices in Germany, the use of separate valve and vascular prostheses leads to cost savings of about 13% compared to the price of a commercially available valved conduit.
Our retrospective study has several limitations. First, patient recruitment was not randomized, and the 2 groups of patients were treated during 2 different time periods. Within these time periods, however, recruitment was consecutive and not selective. Second, 3 different valve prostheses were used in the study group. However, this demonstrates that supraannular valve prostheses of different manufacturers can be used for the self-assembled aortic conduit. Third, there has been no long-term follow-up because of the short time interval between the end of the recruiting period and the writing of this report.
Judging from the short-term results, our data nevertheless suggest that the modified composite graft as described offers excellent surgical results and hemodynamic improvement compared to the standard conduit. In fact, the modified conduit with a St. Jude Regent valve prosthesis has been employed in our institution since 2000 as a standard device for patients requiring aortic root replacement with a mechanical conduit. Up to October 2003, we had implanted this device in 135 patients with excellent operative and early clinical results (30-day mortality of 0.7%).
|
ACKNOWLEDGMENTS
|
|---|
We would like to thank Silvia Martin for preparing this article and Monica Meyer for reviewing it.
|
REFERENCES
|
|---|
- Urbanski PP. Complete aortic root replacement in patients with small aortic annulus. Ann Thorac Surg
2002;73:725–9.
- Bentall H, De Bono A. A technique for complete replacement of the ascending aorta. Thorax
1968;23:338–9.[Abstract/Free Full Text]
- Kouchoukos NT, Marshall WG Jr, Wedige-Stecher TA. Eleven-year experience with composite graft replacement of the ascending aorta and aortic valve. J Thorac Cardiovasc Surg
1986;92:691–705.[Abstract]
- Cabrol C, Pavie A, Gandjbakhch I, Villemot JP, Guiraudon G, Laughlin L, et al. Complete replacement of the ascending aorta with reimplantation of the coronary arteries: new surgical approach. J Thorac Cardiovasc Surg
1981;81:309–15.[Abstract]
- Sekine S, Abe T, Seki K, Shibata Y, Yamagishi I, Kamada M. Dacron coronary graft obstruction after composite graft replacement of aortic root. Ann Thorac Surg
1995;60:1123–6.[Abstract/Free Full Text]
- Panos A, Amahzoune B, Robin J, Champsaur G, Ninet J. Influence of technique of coronary artery implantation on long-term results in composite aortic root replacement. Ann Thorac Surg
2001;72:1497–501.[Abstract/Free Full Text]
- Westaby S, Katsumata T, Vaccari G. Aortic root replacement with coronary button re-implantation: low risk and predictable outcome. Eur J Cardiothorac Surg
2000;17:259–65.[Abstract/Free Full Text]
- Urbanski PP. Aortic root replacement with coronary button reimplantation. Eur J Cardiothorac Surg
2000;18:732.[Free Full Text]
- Liu KX, Yamamoto F, Sekine S, Goto Y, Seki S, Yamagishi I, et al. An effective method for improving hemostasis in aortic root replacement with a composite graft. Heart Vessels
1998;13:237–40.[Medline]
- Pratali S, Milano A, Codecasa R, De Carlo M, Borzoni G, Bortolotti U. Improving hemostasis during replacement of the ascending aorta and aortic valve with a composite graft. Tex Heart Inst J
2000;27:246–9.[Medline]
- Copeland JG 3rd, Rosado LJ, Snyder SL. New technique for improving hemostasis in aortic root replacement with composite graft. Ann Thorac Surg
1993;55:1027–9.[Abstract]
- Michielon G, Salvador L, Da Col U, Valfre C. Modified button-Bentall operation for aortic root replacement: the miniskirt technique. Ann Thorac Surg
2001;72:S1059–64.[Abstract/Free Full Text]
- Tsukui H, Aomi S, Nishida H, Endo M, Koyanagi H. Ostial stenosis of coronary arteries after complete replacement of aortic root using gelatin-resorcinol-formaldehyde glue. Ann Thorac Surg
2001;72:1733–5.[Abstract/Free Full Text]
- Martinelli L, Graffigna A, Guarnerio M, Bonmassari R, Disertori M. Coronary artery narrowing after aortic root reconstruction with resorcinformalin glue. Ann Thorac Surg
2000;70:1701–2.[Abstract/Free Full Text]
- Bingley JA, Gardner MA, Stafford EG, Mau TK, Pohlner PG, Tam RK, et al. Late complications of tissue glues in aortic surgery. Ann Thorac Surg
2000;69:1764–8.[Abstract/Free Full Text]
- Mesana TG, Caus T, Gaubert J, Collart F, Ayari R, Bartoli J, et al. Late complications after prosthetic replacement of the ascending aorta: what did we learn from routine magnetic resonance imaging follow-up? Eur J Cardiothorac Surg
2000;18:313–20.[Abstract/Free Full Text]
- Yakut C. A new modified Bentall procedure: the flanged technique. Ann Thorac Surg
2001;71:2050–2.[Abstract/Free Full Text]
- Khan S, Trento A. Is it better on top? The triumph of supra-annular valves. J Thorac Cardiovasc Surg
2001;122:645–6.[Free Full Text]
- Vitale N, Caldarera I, Muneretto C, Sinatra R, Scafuri A, Di Rosa E, et al. Clinical evaluation of St. Jude Medical Hemodynamic Plus versus standard aortic valve prostheses: the Italian multicenter, prospective, randomized study. J Thorac Cardiovasc Surg
2001;122:691–8.[Abstract/Free Full Text]
- Pibarot P, Dumesnil JG. Hemodynamic and clinical impact of prosthesis-patient mismatch in the aortic valve position and its prevention. J Am Coll Cardiol
2000;36:1131–41.[Abstract/Free Full Text]
This article has been cited by other articles:
|
|
|
|
 
P. P. Urbanski and A. Diegeler
Modified Bentall operation
Eur. J. Cardiothorac. Surg.,
October 1, 2008;
34(4):
926 - 927.
[Full Text]
[PDF]
|
|
|
TOP
ABSTRACT
INTRODUCTION
23 mm