ORIGINAL ARTICLE – ADULT CARDIAC
Interactive CardioVascular and Thoracic Surgery 18 (2014) 159–163 doi:10.1093/icvts/ivt447 Advance Access publication 30 October 2013
Long-term results after aortic root replacement using self-assembled valve composite grafts in patients with small aortic annulus Paul P. Urbanski*, Witold Dinstak, Wilko Rents, Nicolas Heinz and Anno Diegeler
* Corresponding author. Herz- und Gefaess-Klinik, Salzburger Leite 1, 97616 Bad Neustadt, Germany. Tel: +49-9771-662416; fax: +49-9771-651219; e-mail: [email protected] (P. Urbanski). Received 26 June 2013; received in revised form 11 September 2013; accepted 17 September 2013
Abstract OBJECTIVES: The study was aimed to evaluate operative and long-term results after complete root replacement using self-assembled valve composite grafts in patients with a small aortic annulus. METHODS: Among 547 consecutive patients who received the Bentall procedure between 2000 and 2012, a total of 29 patients (61 ± 10; range 42–79 years) had an annulus of ≤20 mm (mean 19.0 ± 0.9). Patients with a native aortic valve (22) suffered from stenosis, insufficiency or mixed defect in 10, 10 and 2 cases, respectively. Among the remaining 7 patients with an artificial aortic valve, there were 3 symptomatic prosthesis–patient mismatches, 3 valve prosthesis deteriorations (1 structural and 2 none-structural) and 1 paravalvular leak. Indication for aortic root replacement was true or false aneurysm, porcelain aorta and intraoperative aortic wall injury in 17, 6 and 6 patients, respectively. RESULTS: The composite graft for complete aortic root replacement was assembled using a mechanical (26) or biological (3) valve prosthesis placed inside a vascular graft with a median size of 24 (range 22–26) mm. The margin of the tube beneath the valve was anastomosed to the aortic annulus, and coronary ostia were implanted in the usual manner. The mean transvalvular gradient at discharge was 10.8 ± 3.9 mmHg and remained virtually unchanged at the follow-up completed for all patients. Early mortality was 0. During the mean follow-up of 95.8 ± 43.7 months, 2 patients died (54 and 146 months after surgery) due to pulmonary embolism and myocardial infarction, respectively. CONCLUSIONS: In patients with a small aortic annulus who need complete aortic root replacement, an oversizing of the valve can be easily achieved using modified, self-assembled composite grafts. Offering excellent haemodynamic characteristics, these grafts lead to prevention of prosthesis–patient mismatch and result in very good and durable functional and clinical results. Keywords: Aortic surgery • Aortic root replacement • Aortic valve • Prosthesis–patient mismatch
INTRODUCTION The use of a valved conduit consisting of mechanical or biological valve prostheses and a vascular graft, as described first by Bentall and De Bono in 1968, has become a standard surgical technique for complete aortic root replacement [1–3]. In accordance with the most common aortic root pathology necessitating its replacement, the aortic annulus is normally large enough to allow an implantation of an aortic valve conduit with a sufficient aortic valve prosthesis size. However, in rare cases in which aortic root pathology is combined with a small aortic annulus, the latter can hinder an implantation of a standard conduit with an adequate valve orifice area and even lead to prosthesis–patient mismatch (PPM). Although the clinical implications of PPM still remain controversial, we agree with others that a severe mismatch should always be avoided and a moderate mismatch, even if it seems to be well tolerated in patients with normal ejection fraction, should be avoided, at least in young and active patients [4–9]. The use of modified self-assembled composite grafts, which combines the
Cabrol and Kouchoukos techniques (the prosthesis is placed inside the vascular tube and the coronary ostia are directly implanted into the conduit as buttons), can be a very valuable option in such situations because it enables a considerable valve oversizing [10, 11]. The aim of the study was to evaluate operative and long-term results after complete aortic root replacement in patients with a small aortic annulus in whom modified, self-assembled composite grafts with oversized aortic valve prostheses were used.
PATIENTS AND METHODS Among 547 consecutive patients who received the Bentall procedure between August 2000 and May 2012, 29 patients with a mean age of 61 ± 10 years (range 42–79 years) had an annulus of ≤20 mm (mean 19 ± 0.9). Patients with a native aortic valve (22) suffered from stenosis, insufficiency or mixed defect in 10, 10 and 2 cases, respectively. Among 7 patients with an artificial aortic
© The Author 2013. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
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valve, there were 3 symptomatic PPMs, 3 valve prosthesis deteriorations (1 structural and 2 none-structural) and 1 paravalvular leak. Indication for aortic root replacement was chronic aneurysm or dissection, porcelain aorta and intraoperative aortic wall injury in 17, 6 and 6 patients, respectively. Previous cardiac surgery was performed in 6 patients once and in 1 patient twice. The latter, after previous repair of acute aortic dissection, suffered from additional complex aortic pathologies such as porcelain aorta after previous use of gelatin resorcinol formalin glue, anastomotic false aneurysm and progressive aneurysm of the chronic dissected aortic arch. Preoperative diagnostics comprised echocardiography, heart catheterization and CT angiography if appropriate and, starting in 2002, was completed by a neurovascular examination in patients in whom aortic arch repair was performed using unilateral cerebral perfusion under mild hypothermia. For the purposes of this observational study, all perioperative data were collected
Table 1: Preoperative patient characteristics Characteristics
No (%) or mean ± SD (range)
Sex male Age (years) Aortic annulus (mm) Body surface area (m²) Aortic valve defect Native aortic valve Stenosis Insufficiency Mixed Artificial aortic valve PPM Non-structural deterioration Structural deterioration Paravalvular leak Concomitant disease Hypertension Coronary heart diseasea COPD Previous cardiac surgery
3 (10) 61 ± 10 (42–79) 19 ± 0.9 (17–20) 1.76 ± 0.19 (1.25–2.05) 29 (100) 22 (76) 10 (35) 10 (35) 2 (6) 7 (24) 3 (10) 2 (6) 1 (3) 1 (3) 35 (76.1) 6 (13.0) 4 (8.7) 7 (24)
a
With surgically relevant stenosis. COPD: chronic obstructive pulmonary disease (requiring long-term therapy in anamnesis); PPM: prosthesis–patient mismatch.
prospectively and the patients were enrolled into assessment to achieve a follow-up time of at least 1 year. The preoperative characteristics of all the patients are given in Table 1, while Table 2 provides detailed characteristics of 3 patients suffering from PPM after previous aortic valve replacement.
Surgical technique Complete aortic root replacement was carried out using selfmade mechanical or biological composite grafts, which have been established as the routine in our centre for biological valves in 1998 and for mechanical valves in 2000 [12, 13]. In this technique, a mechanical valve (26) or a xenograft (3) was placed into the collagen-coated woven polyester vascular graft (InterGard; InterVascular, MAQUET Cardiovascular, La Ciotat, France), leaving a free tube margin of 5 mm, and fixed to the tube with a running mattress polypropylene suture. The composite graft was anastomosed to the aortic annulus with pledgeted interrupted mattress sutures passing the sutures through the aortic annulus from the ventricle to the aortic side and the free margin of the composite graft beneath the valve prosthesis from inside to outside to allow a considerable oversizing of the aortic valve, as described and illustrated in detail previously [10–13]. Coronary ostia were implanted using the Kouchoukos button technique [14] in all but 1 patient, in whom coronary revascularizations were performed due to ostial calcifications making direct implantation impossible. The supra-annular location of the valve prosthesis did not interfere adversely with the implantation of the coronary ostia, neither in the population described nor in our entire experience with this technique up to date counting almost 600 surgeries. Coronary revascularizations due to coronary heart disease were carried out in 10 patients. In 5 patients in whom aortic arch repair was performed before 2003, a femoral artery was cannulated for arterial return, and circulatory arrest under deep hypothermia was used for protection. In the remaining 11 patients, a common carotid artery was cannulated, and during mild hypothermic circulatory arrest, a unilateral cerebral perfusion was performed as described elsewhere [15]. The surgical procedures and the operative data are summarized in Table 3. All perioperative data were collected prospectively and retrospective analysis was performed. The patients were followed up by echocardiography performed in our outpatient clinic or by their cardiologist, from whom the written documents and
Table 2: Preoperative characteristics of patients presenting PPM after previous AVR No
1 2 3 a
Sex
< , ,
CCP
No No No
After AVR
After modified Bentall with re-AVR
Prosthesis used
TG max/mean (mmHg)
IEOA (cm²/m²)
Functional class NYHA
Prosthesis used
TG max/mean (mmHg)
IEOA (cm²/m²)
Functional class (NYHA)
St. Jude 19a St. Jude 19a Soprano 18b
79/43 89/55 90/52
0.5 0.5 0.7
II II III
Regent 23a Regent 23a Perimount 23c
17/9 17/11 12/6
1.2 1.2 1.0
I I I
St. Jude Medical. Sorin Biomedica (Sallugia, Italy). Edwards Lifesciences (Irvine, CA, USA). PPM: prosthesis–patient mismatch; AVR: aortic valve replacement; re-AVR: aortic valve re-replacement; TG: transvalvular gradient; EOAI: indexed effective orifice area; NYHA: New York Heart Association; CCP: concomitant cardiac pathology like coronary heart disease or similar.
b c
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Variables
No (%) or mean ± SD (range)
Arch involvement in aortic replacement Hemiarch replacement Total/subtotal arch replacement CABG due to CHD CABG due to ostial pathology Myectomy Mitral valve repair/replacement CPB duration (min) Aortic cross-clamp time (min)a Circulatory arrest time (min)b
16 (55) 9 (31) 7 (24) 10 (35) 1 (3) 10 (35) 3 (10) 194 ± 53 (69–377) 120 ± 36 (48–214) 40 ± 24 (9–135)
a
Including circulatory arrest. b Performed using deep hypothermia in 5 patients and mild hypothermia with unilateral cerebral perfusion in 11 patients. CABG: coronary artery bypass grafting; CPB: cardiopulmonary bypass; CHD: coronary heart disease.
echocardiographic images were requested and reviewed. The data analysis was performed according to reporting guidelines [16].
Statistical analysis The statistical analysis was performed with the SPSS software (SPSS, Inc., Chicago, IL, USA). Values in the tables and text are expressed as mean ± standard deviation unless otherwise indicated. Actuarial survival was estimated by the Kaplan–Meier method.
RESULTS Operative data and early mortality and morbidity The average diameter of the patients’ aortic annulus, as measured during surgery with a valve sizer, was 19.0 ± 0.9 mm, for which a vascular prosthesis with a median size of 24 (range 22–26) mm was used. In 26 patients, mechanical aortic valve prostheses (St. Jude Regent 21 or 23; St. Jude Medical, St. Paul, MN, USA or ATS AP 20 or 22; Medtronic, Minneapolis, MN, USA) were used for assembling composite grafts. Among 3 patients with biological valve prostheses, 2 had SPV Toronto 25 (St. Jude Medical) and 1 had Carpentier-Edwards Perimount 23 (Edwards Lifesciences, Irvine, CA, USA). Operative data are shown in detail in Table 2. All patients survived the surgery and were discharged from the hospital 11 days thereafter, on average. No patient needed re-thoracotomy or presented pericardial effusion during the postoperative course. Both 30- and 90-day postoperative mortality rates were 0. Permanent neurological deficit (stroke minor) occurred in 1 patient (75-year old female) with porcelain aorta operated on using deep hypothermic circulatory arrest. She did not present any residuals nor suffered any further neurological events during a follow-up of almost 12 years. Temporary neurological dysfunction such as confusion, delirium or agitation lasting >48 h but without focal deficit occurred in 2 (7%). One patient needed temporary dialysis after surgery, and 4 underwent pacemaker implantation before discharge.
Figure 1: Actuarial survival (Kaplan–Meier) without cardiac and/or aortic re-intervention.
The most frequent postoperative complication, which occurred in 7 patients, was respiratory insufficiency necessitating prolonged ventilation (>24 h) or re-intubation. Two of these patients required tracheotomy.
Survival and late outcome Follow-up data were available for all patients. The mean follow-up was 95.8 ± 43.7 months, totalling 232 patient-years. A total of 2 patients died during the entire postoperative period resulting in an overall survival rate of 93% at the median follow-up of 96 (range 12.1–154.6) months. One patient died 54 months after surgery due to a pulmonary embolism and another one 146 months after surgery due to myocardial infarction. The linearized death rate was 0.86%/year and the actuarial survival at 10 years was 96 ± 4% (Fig. 1). There was only 1 thromboembolic event (stroke minor with complete regression of symptoms after few weeks) in a 70-year old female patient. Ten months before the event, she underwent an aortic valve re-replacement using a composite graft due to non-structural valve prosthesis deterioration and porcelain aorta. Concomitantly, a hemiarch repair, mitral valve replacement and myectomy were performed. She was one of a total of 7 patients in the cohort who suffered from chronic atrial fibrillation. There were no haemorrhagic events noticed in any patient during the entire follow-up time, although all the 26 patients with a mechanical valve prosthesis were given warfarin. There were also no other valve-related events, such as endocarditis or valve deterioration. No patient required any cardiac or aortic intervention or reoperation. At the last follow-up, all survivors presented functional Class (New York Heart Association) I (n = 13) or II (n = 14).
Functional data The echocardiography performed during the hospital stay showed excellent valve function with no paravalvular leakages and a mean transvalvular gradient of 10.8 ± 3.9 mmHg. The indexed effective orifice area (EOAI) averaged 1.2 ± 0.15 cm²/m². The lowest value, which was present in 3 patients, was 0.9 cm²/m². An improvement in EOAI was considerable in patients who suffered from the PPM after a primary aortic valve replacement. In these 3 patients, EOAI was 0.5, 0.5 and 0.7 cm²/m², respectively, and after complete root replacement, it improved to 1.2, 1.2 and 1.0 cm²/m², respectively (Table 2).
ORIGINAL ARTICLE
Table 3: Operative data
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At the last echocardiography performed, on average 87.8 ± 45.6 months after surgery, no pathological alterations were noticed in any patient, and there was no relevant change in the transvalvular gradient.
DISCUSSION Although combination of aortic root pathology with aortic valve defect and narrow aortic annulus is a rare surgical issue, a growing number of these patients can be expected. The possible reason for this is an increase in patient age and subsequent increase in complex aortic root pathologies related to severe calcification or re-do surgery. Even after exclusion of patients with an aortic valve size of 21, which does not seem to present a major haemodynamic problem after aortic valve replacement [5], the rate of patients with an annulus ≤20 mm was 5% of all patients who underwent the Bentall procedure in our series. And 40% of them required aortic root replacement due to severe calcification and/or intraoperative injury of the aortic root. Because a narrow and pathologically changed aortic root is particularly susceptible to injury during surgery, we recommend not to hesitate with the decision to extend the procedure before serious surgical complications occur after mostly disastrous attempts of repairing the injury and further forcing of an isolated aortic valve replacement. The fact that, in experienced hands, a complete aortic root replacement does not adversely impact on early and late outcome when compared with an isolated aortic valve replacement proves a point [17]. While performing complete aortic root repair in patients with a small annulus, there are few surgical options available; however, their practical suitability is at least debatable. The use of biological devices such as pulmonary autograft or homograft can be especially useful if a biological solution is considered. Both offer improved orifice area and, consequently, better haemodynamic features when compared with mechanical valves, but the surgical complexity and limited availability reduces their clinical use, especially in emergency and in complicated pathologies [18, 19]. Stentless valve prostheses seem to be more suitable in such cases [20–22]; however, there is still a concern regarding their durability and potentially limited operability in cases in which the entire artificial aortic root would severely calcify, similar to what is generally seen in homografts [22]. For this reason, even if using stentless valves for root replacement, our preferred technique is to place the valve inside a vascular tube. This enables a safe valve re-replacement within the tube leaving the conduit with the re-implanted coronaries in place [23, 24]. Surgical enlargement of the annulus using patch plasty allows use of larger, commercially available mechanical or biological valve conduits; however, this technique, despite its usefulness in isolated aortic valve replacement, is burdened with an increased risk of bleeding and operative mortality when combined with complete root replacement and, therefore, generally omitted in aortic root surgery [25]. Nevertheless, there is no doubt that this technique would not only increase the surgical complexity, but also prolong cross-clamp times that extend to a range of 3 h or more depending on pathological complexity and surgical experience [20]. Conversely, the technique described in this paper is simple and reproducible. The overall cross-clamp time needed for completing the procedure in our cohort was 120 min on average, despite the concomitant procedures with more than a 50% rate of arch surgery. This technique not only offers the possibility to use a
larger valve and improve the haemodynamics, but also provides excellent haemostatic features by anastomosing the fragile remnants of the aortic annulus (e.g. in re-operations or after extensive decalcification) with the flexible rim of a sealed vascular tube rather than with the rigid and uncoated sewing ring of the valve prosthesis [13]. This suture line can even be additionally secured by sewing the tube rim with the remnants of the aortic base; however, we have exercised such an option only exceptionally. The technique described here enables the use of mechanical and biological valve prostheses in accordance with the clinical situation and the patient’s requirement. The efficacy of this method in patients with a small aortic annulus could be demonstrated not only by favourable transvalvular gradients, but also by excellent long-term results. During the median follow-up of 96 months, only 2 patients died, and even if the cause of death was cardiac in both cases, none was valve-related. In addition, no patient died because of congestive heart failure or even presented any clinical symptoms that could be related to such a failure. In summary, a modified, self-assembled composite graft can be established easily using a vascular graft and any mechanical or biological valve prosthesis in accordance with the patient’s requirement and the surgeon’s preference. The implantation technique is comparable with a classic Bentall procedure, which is very well reproducible, and therefore considered to be the gold standard for complete aortic root replacement. The placement of the valve prosthesis inside a vascular tube enables simple albeit considerable oversizing of the aortic valve in patients with a small aortic annulus. This feature offers very good haemodynamic characteristics with prevention of PPM and results in excellent clinical and functional long-term results.
ACKNOWLEDGEMENTS The authors thank Melissa Lindner and Alexandra Metz for the assistance in preparing this article. Conflict of interest: Paul P. Urbanski is a consultant for and discloses a financial relationship with MAQUET Cardiovascular, Inc.
REFERENCES [1] Bentall H, De Bono A. A technique for complete replacement of the ascending aorta. Thorax 1968;23:338–9. [2] Hagl C, Strauch JT, Spielvogel D, Galla JD, Lansman SL, Squitieri R et al. Is the Bentall procedure for ascending aorta or aortic valve replacement the best approach for long-term event-free survival? Ann Thorac Surg 2003; 76:698–703. [3] Zehr KJ, Orszulak TA, Mullany CJ, Matloobi A, Daly RC, Dearani JA et al. Surgery for aneurysms of the aortic root: a 30-year experience. Circulation 2004;110:1364–71. [4] Pibarot P, Dumesnil JG. Hemodynamic and clinical impact of prothesispatient mismatch in the aortic valve position and its prevention. J Am Coll Cardiol 2000;36:1131–44. [5] Urso S, Sadaba R, Aldamiz-Echevarria G. Is patient-prosthesis mismatch an independent risk factor for early and mid-term overall mortality in adult patients undergoing aortic valve replacement? Interact CardioVasc Thorac Surg 2009;9:510–9. [6] Mannacio VA, De Amicis V, Di Tommaso L, Iorio F, Vosa C. Influence of prosthesis-patient mismatch on exercise-induced arrhythmias: a further aspect after aortic valve replacement. J Thorac Cardiovasc Surg 2009;138: 632–8. [7] Bridges CR, O’Brian SM, Cleveland JC, Savage EB, Gammie JS, Edwards FH et al. Association between indices of prosthesis internal orifice size and
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operative mortality after isolated aortic valve replacement. J Thorac Cardiovasc Surg 2007;133:1012–21. Kohsaka S, Mohan S, Variani S, Lee V, Contreras A, Reul GJ et al. Prosthesis-patient mismatch affects long-term survival after mechanical valve replacement. J Thorac Cardiovasc Surg 2008;135:1076–80. Rao V, Jamieson WRE, Ivanov J, Armstrong S, David TE. Prosthesis-patient mismatch affects survival after aortic valve replacement. Circulation 2000; 102(Suppl III):III-5–9. Urbanski P. New vascular graft for assembling the stentless valve composite graft. Ann Thorac Surg 2007;84:1771–3. Urbanski P. Complete aortic root replacement in patients with small aortic annulus. Ann Thorac Surg 2002;73:725–9. Urbanski P, Diegeler A, Siebel A, Zacher M, Hacker RW. Valved stentless composite graft: clinical outcomes and hemodynamic characteristics. Ann Thorac Surg 2003;75:467–71. Urbanski P, Dinstak W, Frank S, Siebel A, Hacker RW. Modified versus standard mechanical valved aortic conduit. Asian Cardiovasc Thorac Ann 2005;13:53–7. 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. Urbanski PP, Lenos A, Bougioukakis P, Neophytou I, Zacher M, Diegeler A. Mild-to-moderate hypothermia in aortic arch surgery using circulatory arrest: a change of paradigm? Eur J Cardiothorac Surg 2012;41:185–91. Akins CW, Miller DC, Turina MI, Kouchoukos NT, Blackstone EH, Grunkemeier GL et al. Guidelines for reporting mortality and morbidity after cardiac valve interventions. Ann Thorac Surg 2008;85:1490–5.
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[17] Urbanski PP, Wagner M, Zacher M, Hacker RW. Aortic root replacement versus aortic valve replacement: a case-match study. Ann Thorac Surg 2001;72:28–32. [18] Kouchoukos NR. Aortic allograft and pulmonary autografts for replacement of the aortic valve and aortic root. Ann Thorac Surg 1999;67:1846–8. [19] Doss M, Wood JP, Martens S, Wimmer-Greinecker G, Moritz A. Do pulmonary autografts provide better outcomes than mechanical valves? A prospective randomized trial. Ann Thorac Surg 2005;80:2194–8. [20] McCarthy FH, Bavaria JE, Pochettino A, Fox Z, Moeller P, Szeto WY et al. Comparing aortic root replacements: porcine bioroots versus pericardial versus mechanical composite roots: hemodynamic and ventricular remodelling at greater than one-year follow-up. Ann Thorac Surg 2012;94: 1975–82. [21] LeMaire SA, Green SY, Sharma K, Cheung CK, Sameri A, Tsai PI et al. Aortic root replacement with stentless procine xenografts: early and late outcomes in 132 patients. Ann Thorac Surg 2009;87:503–13. [22] Kirsch MEW, Ooka T, Zannis K, Deux J-F, Loisance DY. Bioprosthetic replacement of the ascending thoracic aorta: what are the options? Eur J Cardiothorac Surg 2009;35:77–82. [23] Urbanski PP, Heinz N, Zhan X, Hijazi H, Zacher M, Diegeler A. Modified bio-Bentall procedure: 10-year experience. Eur J Cardiothorac Surg 2010; 37:1317–21. [24] Urbanski PP. Replacement of valve prosthesis within aortic composite graft. Ann Thorac Surg 2009;88:2024–5. [25] Davierwala PM, Borger MA, David TE, Rao V, Maganti M, Yau TM. Reoperation is not an independent predictor of mortality during aortic valve surgery. J Thorac Cardiovasc Surg 2006;131:329–35.
ORIGINAL ARTICLE
P.P. Urbanski et al. / Interactive CardioVascular and Thoracic Surgery
Interactive CardioVascular and Thoracic Surgery 18 (2014) 159–163 doi:10.1093/icvts/ivt447 Advance Access publication 30 October 2013
Long-term results after aortic root replacement using self-assembled valve composite grafts in patients with small aortic annulus Paul P. Urbanski*, Witold Dinstak, Wilko Rents, Nicolas Heinz and Anno Diegeler
* Corresponding author. Herz- und Gefaess-Klinik, Salzburger Leite 1, 97616 Bad Neustadt, Germany. Tel: +49-9771-662416; fax: +49-9771-651219; e-mail: [email protected] (P. Urbanski). Received 26 June 2013; received in revised form 11 September 2013; accepted 17 September 2013
Abstract OBJECTIVES: The study was aimed to evaluate operative and long-term results after complete root replacement using self-assembled valve composite grafts in patients with a small aortic annulus. METHODS: Among 547 consecutive patients who received the Bentall procedure between 2000 and 2012, a total of 29 patients (61 ± 10; range 42–79 years) had an annulus of ≤20 mm (mean 19.0 ± 0.9). Patients with a native aortic valve (22) suffered from stenosis, insufficiency or mixed defect in 10, 10 and 2 cases, respectively. Among the remaining 7 patients with an artificial aortic valve, there were 3 symptomatic prosthesis–patient mismatches, 3 valve prosthesis deteriorations (1 structural and 2 none-structural) and 1 paravalvular leak. Indication for aortic root replacement was true or false aneurysm, porcelain aorta and intraoperative aortic wall injury in 17, 6 and 6 patients, respectively. RESULTS: The composite graft for complete aortic root replacement was assembled using a mechanical (26) or biological (3) valve prosthesis placed inside a vascular graft with a median size of 24 (range 22–26) mm. The margin of the tube beneath the valve was anastomosed to the aortic annulus, and coronary ostia were implanted in the usual manner. The mean transvalvular gradient at discharge was 10.8 ± 3.9 mmHg and remained virtually unchanged at the follow-up completed for all patients. Early mortality was 0. During the mean follow-up of 95.8 ± 43.7 months, 2 patients died (54 and 146 months after surgery) due to pulmonary embolism and myocardial infarction, respectively. CONCLUSIONS: In patients with a small aortic annulus who need complete aortic root replacement, an oversizing of the valve can be easily achieved using modified, self-assembled composite grafts. Offering excellent haemodynamic characteristics, these grafts lead to prevention of prosthesis–patient mismatch and result in very good and durable functional and clinical results. Keywords: Aortic surgery • Aortic root replacement • Aortic valve • Prosthesis–patient mismatch
INTRODUCTION The use of a valved conduit consisting of mechanical or biological valve prostheses and a vascular graft, as described first by Bentall and De Bono in 1968, has become a standard surgical technique for complete aortic root replacement [1–3]. In accordance with the most common aortic root pathology necessitating its replacement, the aortic annulus is normally large enough to allow an implantation of an aortic valve conduit with a sufficient aortic valve prosthesis size. However, in rare cases in which aortic root pathology is combined with a small aortic annulus, the latter can hinder an implantation of a standard conduit with an adequate valve orifice area and even lead to prosthesis–patient mismatch (PPM). Although the clinical implications of PPM still remain controversial, we agree with others that a severe mismatch should always be avoided and a moderate mismatch, even if it seems to be well tolerated in patients with normal ejection fraction, should be avoided, at least in young and active patients [4–9]. The use of modified self-assembled composite grafts, which combines the
Cabrol and Kouchoukos techniques (the prosthesis is placed inside the vascular tube and the coronary ostia are directly implanted into the conduit as buttons), can be a very valuable option in such situations because it enables a considerable valve oversizing [10, 11]. The aim of the study was to evaluate operative and long-term results after complete aortic root replacement in patients with a small aortic annulus in whom modified, self-assembled composite grafts with oversized aortic valve prostheses were used.
PATIENTS AND METHODS Among 547 consecutive patients who received the Bentall procedure between August 2000 and May 2012, 29 patients with a mean age of 61 ± 10 years (range 42–79 years) had an annulus of ≤20 mm (mean 19 ± 0.9). Patients with a native aortic valve (22) suffered from stenosis, insufficiency or mixed defect in 10, 10 and 2 cases, respectively. Among 7 patients with an artificial aortic
© The Author 2013. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
ORIGINAL ARTICLE
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valve, there were 3 symptomatic PPMs, 3 valve prosthesis deteriorations (1 structural and 2 none-structural) and 1 paravalvular leak. Indication for aortic root replacement was chronic aneurysm or dissection, porcelain aorta and intraoperative aortic wall injury in 17, 6 and 6 patients, respectively. Previous cardiac surgery was performed in 6 patients once and in 1 patient twice. The latter, after previous repair of acute aortic dissection, suffered from additional complex aortic pathologies such as porcelain aorta after previous use of gelatin resorcinol formalin glue, anastomotic false aneurysm and progressive aneurysm of the chronic dissected aortic arch. Preoperative diagnostics comprised echocardiography, heart catheterization and CT angiography if appropriate and, starting in 2002, was completed by a neurovascular examination in patients in whom aortic arch repair was performed using unilateral cerebral perfusion under mild hypothermia. For the purposes of this observational study, all perioperative data were collected
Table 1: Preoperative patient characteristics Characteristics
No (%) or mean ± SD (range)
Sex male Age (years) Aortic annulus (mm) Body surface area (m²) Aortic valve defect Native aortic valve Stenosis Insufficiency Mixed Artificial aortic valve PPM Non-structural deterioration Structural deterioration Paravalvular leak Concomitant disease Hypertension Coronary heart diseasea COPD Previous cardiac surgery
3 (10) 61 ± 10 (42–79) 19 ± 0.9 (17–20) 1.76 ± 0.19 (1.25–2.05) 29 (100) 22 (76) 10 (35) 10 (35) 2 (6) 7 (24) 3 (10) 2 (6) 1 (3) 1 (3) 35 (76.1) 6 (13.0) 4 (8.7) 7 (24)
a
With surgically relevant stenosis. COPD: chronic obstructive pulmonary disease (requiring long-term therapy in anamnesis); PPM: prosthesis–patient mismatch.
prospectively and the patients were enrolled into assessment to achieve a follow-up time of at least 1 year. The preoperative characteristics of all the patients are given in Table 1, while Table 2 provides detailed characteristics of 3 patients suffering from PPM after previous aortic valve replacement.
Surgical technique Complete aortic root replacement was carried out using selfmade mechanical or biological composite grafts, which have been established as the routine in our centre for biological valves in 1998 and for mechanical valves in 2000 [12, 13]. In this technique, a mechanical valve (26) or a xenograft (3) was placed into the collagen-coated woven polyester vascular graft (InterGard; InterVascular, MAQUET Cardiovascular, La Ciotat, France), leaving a free tube margin of 5 mm, and fixed to the tube with a running mattress polypropylene suture. The composite graft was anastomosed to the aortic annulus with pledgeted interrupted mattress sutures passing the sutures through the aortic annulus from the ventricle to the aortic side and the free margin of the composite graft beneath the valve prosthesis from inside to outside to allow a considerable oversizing of the aortic valve, as described and illustrated in detail previously [10–13]. Coronary ostia were implanted using the Kouchoukos button technique [14] in all but 1 patient, in whom coronary revascularizations were performed due to ostial calcifications making direct implantation impossible. The supra-annular location of the valve prosthesis did not interfere adversely with the implantation of the coronary ostia, neither in the population described nor in our entire experience with this technique up to date counting almost 600 surgeries. Coronary revascularizations due to coronary heart disease were carried out in 10 patients. In 5 patients in whom aortic arch repair was performed before 2003, a femoral artery was cannulated for arterial return, and circulatory arrest under deep hypothermia was used for protection. In the remaining 11 patients, a common carotid artery was cannulated, and during mild hypothermic circulatory arrest, a unilateral cerebral perfusion was performed as described elsewhere [15]. The surgical procedures and the operative data are summarized in Table 3. All perioperative data were collected prospectively and retrospective analysis was performed. The patients were followed up by echocardiography performed in our outpatient clinic or by their cardiologist, from whom the written documents and
Table 2: Preoperative characteristics of patients presenting PPM after previous AVR No
1 2 3 a
Sex
< , ,
CCP
No No No
After AVR
After modified Bentall with re-AVR
Prosthesis used
TG max/mean (mmHg)
IEOA (cm²/m²)
Functional class NYHA
Prosthesis used
TG max/mean (mmHg)
IEOA (cm²/m²)
Functional class (NYHA)
St. Jude 19a St. Jude 19a Soprano 18b
79/43 89/55 90/52
0.5 0.5 0.7
II II III
Regent 23a Regent 23a Perimount 23c
17/9 17/11 12/6
1.2 1.2 1.0
I I I
St. Jude Medical. Sorin Biomedica (Sallugia, Italy). Edwards Lifesciences (Irvine, CA, USA). PPM: prosthesis–patient mismatch; AVR: aortic valve replacement; re-AVR: aortic valve re-replacement; TG: transvalvular gradient; EOAI: indexed effective orifice area; NYHA: New York Heart Association; CCP: concomitant cardiac pathology like coronary heart disease or similar.
b c
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Variables
No (%) or mean ± SD (range)
Arch involvement in aortic replacement Hemiarch replacement Total/subtotal arch replacement CABG due to CHD CABG due to ostial pathology Myectomy Mitral valve repair/replacement CPB duration (min) Aortic cross-clamp time (min)a Circulatory arrest time (min)b
16 (55) 9 (31) 7 (24) 10 (35) 1 (3) 10 (35) 3 (10) 194 ± 53 (69–377) 120 ± 36 (48–214) 40 ± 24 (9–135)
a
Including circulatory arrest. b Performed using deep hypothermia in 5 patients and mild hypothermia with unilateral cerebral perfusion in 11 patients. CABG: coronary artery bypass grafting; CPB: cardiopulmonary bypass; CHD: coronary heart disease.
echocardiographic images were requested and reviewed. The data analysis was performed according to reporting guidelines [16].
Statistical analysis The statistical analysis was performed with the SPSS software (SPSS, Inc., Chicago, IL, USA). Values in the tables and text are expressed as mean ± standard deviation unless otherwise indicated. Actuarial survival was estimated by the Kaplan–Meier method.
RESULTS Operative data and early mortality and morbidity The average diameter of the patients’ aortic annulus, as measured during surgery with a valve sizer, was 19.0 ± 0.9 mm, for which a vascular prosthesis with a median size of 24 (range 22–26) mm was used. In 26 patients, mechanical aortic valve prostheses (St. Jude Regent 21 or 23; St. Jude Medical, St. Paul, MN, USA or ATS AP 20 or 22; Medtronic, Minneapolis, MN, USA) were used for assembling composite grafts. Among 3 patients with biological valve prostheses, 2 had SPV Toronto 25 (St. Jude Medical) and 1 had Carpentier-Edwards Perimount 23 (Edwards Lifesciences, Irvine, CA, USA). Operative data are shown in detail in Table 2. All patients survived the surgery and were discharged from the hospital 11 days thereafter, on average. No patient needed re-thoracotomy or presented pericardial effusion during the postoperative course. Both 30- and 90-day postoperative mortality rates were 0. Permanent neurological deficit (stroke minor) occurred in 1 patient (75-year old female) with porcelain aorta operated on using deep hypothermic circulatory arrest. She did not present any residuals nor suffered any further neurological events during a follow-up of almost 12 years. Temporary neurological dysfunction such as confusion, delirium or agitation lasting >48 h but without focal deficit occurred in 2 (7%). One patient needed temporary dialysis after surgery, and 4 underwent pacemaker implantation before discharge.
Figure 1: Actuarial survival (Kaplan–Meier) without cardiac and/or aortic re-intervention.
The most frequent postoperative complication, which occurred in 7 patients, was respiratory insufficiency necessitating prolonged ventilation (>24 h) or re-intubation. Two of these patients required tracheotomy.
Survival and late outcome Follow-up data were available for all patients. The mean follow-up was 95.8 ± 43.7 months, totalling 232 patient-years. A total of 2 patients died during the entire postoperative period resulting in an overall survival rate of 93% at the median follow-up of 96 (range 12.1–154.6) months. One patient died 54 months after surgery due to a pulmonary embolism and another one 146 months after surgery due to myocardial infarction. The linearized death rate was 0.86%/year and the actuarial survival at 10 years was 96 ± 4% (Fig. 1). There was only 1 thromboembolic event (stroke minor with complete regression of symptoms after few weeks) in a 70-year old female patient. Ten months before the event, she underwent an aortic valve re-replacement using a composite graft due to non-structural valve prosthesis deterioration and porcelain aorta. Concomitantly, a hemiarch repair, mitral valve replacement and myectomy were performed. She was one of a total of 7 patients in the cohort who suffered from chronic atrial fibrillation. There were no haemorrhagic events noticed in any patient during the entire follow-up time, although all the 26 patients with a mechanical valve prosthesis were given warfarin. There were also no other valve-related events, such as endocarditis or valve deterioration. No patient required any cardiac or aortic intervention or reoperation. At the last follow-up, all survivors presented functional Class (New York Heart Association) I (n = 13) or II (n = 14).
Functional data The echocardiography performed during the hospital stay showed excellent valve function with no paravalvular leakages and a mean transvalvular gradient of 10.8 ± 3.9 mmHg. The indexed effective orifice area (EOAI) averaged 1.2 ± 0.15 cm²/m². The lowest value, which was present in 3 patients, was 0.9 cm²/m². An improvement in EOAI was considerable in patients who suffered from the PPM after a primary aortic valve replacement. In these 3 patients, EOAI was 0.5, 0.5 and 0.7 cm²/m², respectively, and after complete root replacement, it improved to 1.2, 1.2 and 1.0 cm²/m², respectively (Table 2).
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Table 3: Operative data
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At the last echocardiography performed, on average 87.8 ± 45.6 months after surgery, no pathological alterations were noticed in any patient, and there was no relevant change in the transvalvular gradient.
DISCUSSION Although combination of aortic root pathology with aortic valve defect and narrow aortic annulus is a rare surgical issue, a growing number of these patients can be expected. The possible reason for this is an increase in patient age and subsequent increase in complex aortic root pathologies related to severe calcification or re-do surgery. Even after exclusion of patients with an aortic valve size of 21, which does not seem to present a major haemodynamic problem after aortic valve replacement [5], the rate of patients with an annulus ≤20 mm was 5% of all patients who underwent the Bentall procedure in our series. And 40% of them required aortic root replacement due to severe calcification and/or intraoperative injury of the aortic root. Because a narrow and pathologically changed aortic root is particularly susceptible to injury during surgery, we recommend not to hesitate with the decision to extend the procedure before serious surgical complications occur after mostly disastrous attempts of repairing the injury and further forcing of an isolated aortic valve replacement. The fact that, in experienced hands, a complete aortic root replacement does not adversely impact on early and late outcome when compared with an isolated aortic valve replacement proves a point [17]. While performing complete aortic root repair in patients with a small annulus, there are few surgical options available; however, their practical suitability is at least debatable. The use of biological devices such as pulmonary autograft or homograft can be especially useful if a biological solution is considered. Both offer improved orifice area and, consequently, better haemodynamic features when compared with mechanical valves, but the surgical complexity and limited availability reduces their clinical use, especially in emergency and in complicated pathologies [18, 19]. Stentless valve prostheses seem to be more suitable in such cases [20–22]; however, there is still a concern regarding their durability and potentially limited operability in cases in which the entire artificial aortic root would severely calcify, similar to what is generally seen in homografts [22]. For this reason, even if using stentless valves for root replacement, our preferred technique is to place the valve inside a vascular tube. This enables a safe valve re-replacement within the tube leaving the conduit with the re-implanted coronaries in place [23, 24]. Surgical enlargement of the annulus using patch plasty allows use of larger, commercially available mechanical or biological valve conduits; however, this technique, despite its usefulness in isolated aortic valve replacement, is burdened with an increased risk of bleeding and operative mortality when combined with complete root replacement and, therefore, generally omitted in aortic root surgery [25]. Nevertheless, there is no doubt that this technique would not only increase the surgical complexity, but also prolong cross-clamp times that extend to a range of 3 h or more depending on pathological complexity and surgical experience [20]. Conversely, the technique described in this paper is simple and reproducible. The overall cross-clamp time needed for completing the procedure in our cohort was 120 min on average, despite the concomitant procedures with more than a 50% rate of arch surgery. This technique not only offers the possibility to use a
larger valve and improve the haemodynamics, but also provides excellent haemostatic features by anastomosing the fragile remnants of the aortic annulus (e.g. in re-operations or after extensive decalcification) with the flexible rim of a sealed vascular tube rather than with the rigid and uncoated sewing ring of the valve prosthesis [13]. This suture line can even be additionally secured by sewing the tube rim with the remnants of the aortic base; however, we have exercised such an option only exceptionally. The technique described here enables the use of mechanical and biological valve prostheses in accordance with the clinical situation and the patient’s requirement. The efficacy of this method in patients with a small aortic annulus could be demonstrated not only by favourable transvalvular gradients, but also by excellent long-term results. During the median follow-up of 96 months, only 2 patients died, and even if the cause of death was cardiac in both cases, none was valve-related. In addition, no patient died because of congestive heart failure or even presented any clinical symptoms that could be related to such a failure. In summary, a modified, self-assembled composite graft can be established easily using a vascular graft and any mechanical or biological valve prosthesis in accordance with the patient’s requirement and the surgeon’s preference. The implantation technique is comparable with a classic Bentall procedure, which is very well reproducible, and therefore considered to be the gold standard for complete aortic root replacement. The placement of the valve prosthesis inside a vascular tube enables simple albeit considerable oversizing of the aortic valve in patients with a small aortic annulus. This feature offers very good haemodynamic characteristics with prevention of PPM and results in excellent clinical and functional long-term results.
ACKNOWLEDGEMENTS The authors thank Melissa Lindner and Alexandra Metz for the assistance in preparing this article. Conflict of interest: Paul P. Urbanski is a consultant for and discloses a financial relationship with MAQUET Cardiovascular, Inc.
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