Eur J Cardiothorac Surg 1999;15:803-808
© 1999 Elsevier Science NL
Replacement of ascending aorta with aortic valve reimplantation: midterm results
Wolfgang Harringer,
Klaus Pethig,
Christian Hagl,
Thorsten Wahlers,
Jochen Cremer,
Axel Haverich
Division of Thoracic and Cardiovascular Surgery, Hannover Medical School, 30623Hannover, Germany
Received 23 November 1998;
accepted 11 March 1999.
Corresponding author. Tel.: +49-511-532-6580; fax.: +49-511-532-5404
e-mail: harringer{at}thg.mh-hannover.de
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Abstract
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Objective: Aneurysms of the aortic root lead to aortic valve incompetence due to dilatation of the sinotubular junction and annuloaortic ectasia. Reimplantation of the native, structurally intact aortic valve within a Dacron tube graft corrects annular ectasia as well as dilatation of sinotubular junction and aortic sinuses. Durability of this valve repair with respect to increased mechanical stress on valve cusps is discussed controversially and is yet unknown. Methods: Since 7/93, replacement of the ascending aorta with repair of the aortic valve was performed in 48 patients (34 male, 14 female; 47±20 years) with aortic insufficiency and aneurysm of the aortic root. Fifteen patients (31%) had Marfan's syndrome and five patients (10%) had an aortic dissection type A (two acute, three chronic). In 11 patients (23%), concomitant replacement of the aortic arch was necessary utilizing elephant trunk technique in two patients. Additionally, one patient required mitral valve repair and two other patients coronary artery bypass grafts. Clinical and echocardiographic follow-up was performed in 6–12 month intervals for a cumulative study period of 100 patient years. Results: There were no operative deaths. Two patients (4%) died 5 and 20 months postoperatively. One additional patient experienced a TIA within the first postoperative week. Three patients (6%) with an early postoperative aortic insufficiency (AI)>1 required aortic valve replacement after 9, 11, and 14 months due to progressive AI. In these patients, distortion of the aortic root geometry led to valve incompetence. All other patients have no or mild aortic insufficiency. The repair now remains stable for up to 63 months (mean 25±18 months). Other valve related complications did not occur. Conclusions: Our results demonstrate that this type of aortic valve repair achieves excellent results in selected patients. Perfect coaptation of valve cusps during the repair with no or only trace AI at initial echocardiography seems to be essential for durability.
Key Words: Aorta • Valves • Regurgitation • Surgery
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1. Introduction
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Aneurysms of the proximal ascending aorta represent a rare but potentially life threatening disease (Fig. 1)
[1,2]. Major complications of the aneurysmatic aorta include acute dissection, rupture, and aortic valve incompetence. Despite structurally intact aortic valve cusps even severe secondary aortic regurgitation can occur in these patients. Dilatation of the sinotubular junction and/or annular ectasia result in geometric distortion of the aortic valve with reduction of cusp coaptation leading to central aortic insufficiency [3,4]. Standard surgical therapy for patients reaching a critical aortic diameter or hemodynamically relevant aortic incompetence is replacement of the ascending aorta and aortic valve with a valved conduit. Reported results demonstrate that this technique achieves excellent results with low patient morbidity and mortality [5–7]. However, thromboembolic and anticoagulant related complications of the mechanical valve prosthesis represent a potential disadvantage for the long-term patient outcome. Stimulated by the results of mitral valve reconstruction, interest in aortic valve repair has increased. High mechanical stress on the aortic valve as well as a relatively small cusp coaptation area and lack of aortic root stabilization has led to insufficient results in the past [8]. Valvular incompetence due to geometric distortion of the aneurysmatic aortic root with normal valve cusps probably represents ideal circumstances for aortic valve repair. Various techniques have been reported in these patients to replace the aneurysmatic aorta with preservation of the valve and, if necessary, correction of aortic insufficiency. Since 1993 we have used almost exclusively the technique reported by David and Feindel in 1992 with reimplantation of the aortic valve within a Dacron prosthesis [4]. The aim of this report is to summarize our experience with this technique over a 5-year interval.
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2. Patients and methods
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Between June 1993 and March 1998, 48 patients (34 male, 14 female; mean age 47±19 years; range 9–76 years) underwent aortic root replacement with preservation of the aortic valve. All patients had an aneurysm of the ascending aorta with inclusion of the aortic root (mean diameter 6.3±1.3 cm). In 11 patients (23%), extension of the aneurysm into the aortic arch was present. In five patients (10%), aortic dissection (three chronic, two acute) was the underlying pathology. Two patients required additional coronary artery revascularization and one further patient underwent mitral valve repair as a concomitant procedure. Clinical characteristics of Marfan's syndrome were present in 15 (31%) patients. Indications for operation are shown in Table 1. Coronary angiography, aortic root angiogram, transthoracic echocardiography, as well as CT-scan or MRI were diagnostic procedures routinely performed. Final decision to preserve the aortic valve was done intraoperatively after inspection of valve cusps and root geometry. Routine intraoperative control of aortic valve function was done with transesophageal echocardiography. All patients received either aspirin or coumadin for 2 months postoperatively. Follow-up was performed clinically and with transthoracic color Doppler echocardiography after 3, 6, and 12 months, and yearly intervals thereafter. Valve morphology as well as systolic and diastolic function were assessed in accordance with published criteria [9,10]. Aortic regurgitation was assessed semiquantitatively as: 0 none, I minimal, II mild, III moderate, IV severe. Infectious, thromboembolic, and bleeding complications were reported as required by the AATS/STS guidelines [11]. The cumulative follow-up period was 1204 months with a minimum of 6 months and a maximum of 63 months (25±18; mean±SD).
2.1. Statistical analysis
Continuous variables are expressed as mean plus or minus one standard deviation (SD), actuarial data are reported as mean probability estimates. The statistical significance of differences in aortic insufficiency between preoperative and postoperative echocardiograms was tested using a paired Student's t-test. A P value of <0.05 was considered significant.
2.2. Surgical technique
Standard median sternotomy as well as extracorporeal circulation techniques were used in all patients. Myocardial protection was performed with repetitive doses of cold blood cardioplegia in an antegrade as well as retrograde fashion. Following aortotomy and aortic valve as well as root inspection, decision for valve reconstruction was made. Excision of coronary ostia and resection of aortic sinuses up to a remnant of 2–3 mm as well as external dissection and mobilization of the aortic root was then performed. Initially, prosthesis diameter was calculated from the diameter of the left ventricular outflow tract and the height of the aortic cusps using the calculation as suggested by David and Feindel [12]. During the course of the study the choice of prosthesis diameter was altered, utilizing a standard valve sizer and traction sutures on the commissures to assess the width of the sinotubular junction which achieves sufficient cusp closure. Ideal valve coaptation was considered when 30–50% of cusp area was involved. Mean diameter of prostheses was 27±1.2 mm. Size distribution is reported in Fig. 2.
Proximal anastomosis was performed with 16 threads of 3/0 coated polyester fiber (Ethibond®, Ethicon Inc.) as horizontal mattress sutures, placed through the annulus underneath the valve. The aortic cuff including the commissures is then reimplanted into the Dacron prosthesis with three 4/0 polypropylene sutures (Prolene®, Ethicon Inc.) in running technique. Utmost care was taken to achieve correct cusp geometry as well as sufficient height of commissural resuspension within the prosthesis (Fig. 3)
. Additionally, five patients (10%) required an additional Trusler valvuloplasty to correct an elongated free margin, primarily of the non-coronary cusp [13]. Three of these five patients had a Marfan's syndrome. Reanastomoses of coronary ostia in button technique completed aortic root reconstruction. In the case of more extensive ascending aortic or arch replacement, a second prosthesis was used.
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3. Results
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In all 48 patients preservation of the aortic valve was successful. No patient died within 30 days or in hospital. Intraoperative variables are presented in Table 2. In 11 patients concomitant partial or total aortic arch replacement was necessary, utilizing elephant trunk technique in two patients. Hypothermic circulatory arrest time ranged from 7–32 min (mean 17±8 min).
Perioperatively, 1 patient suffered from a transient ischemic attack (resolving completely) and two patients required rethoracotomy due to bleeding. Aortic valve incompetence was reduced significantly from 2.7±0.8 preoperatively, to 0.4±0.5 postoperatively (P<0.01). Mean postoperative pressure gradient was 6±3 mmHg and remained unchanged throughout the study period. Aortic valve function remained stable during follow-up in the majority of patients (n=41) with either no (n=30) or minimal (n=11) aortic valve incompetence (Table 3). Three patients (one Marfan) developed progressive AI during the first postoperative year and continued now stable in grade II with no further deterioration or increase in left ventricular dimensions. Three additional patients had to be reoperated 9, 11, and 14 months postoperatively due to worsening aortic insufficiency (grade III). One of these patients had clinical signs of Marfan's syndrome. At reoperation, cusp prolapse due to inadequate technique could be identified in two patients and inflammatory cusp lesions were found in one patient with Wegener's granulomatosis, renal insufficiency, and hemodialysis. All three patients already demonstrated less than optimal cusp coaptation with aortic regurgitation >grade I early postoperatively. At reoperation, mechanical valve replacement was performed within the Dacron prosthesis without difficulties. All patients recovered promptly from the second operation. None of the five patients with additional Trusler valvuloplasty required reoperation. Four of these patients demonstrated AI grade 0–I, and one patient stable AI grade II at the last visit.
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Table 3. Semiquantitative assessment of aortic insufficiency before repair, early postoperative and last follow-up visit
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Two patients, both 76 years old, died during follow-up. One lady with ischemic heart disease died at home from sudden cardiac death 20 months postoperatively. The other patient suffered from bacterial mitral valve endocarditis with aortic root abscess 5 months after the operation. He died 3 days after mitral valve replacement, pericardial reconstruction of the left atrium and implantation of a valved conduit in septic shock. The aortic valve repair was found intact but infection of the prostheses was present in the acoronary sinus. Whether this was the primary focus or infection occurred as a result of mitral valve endocarditis remains open.
Actuarial freedom from reoperation was 95% at 1 year, 93% at 2 years, and 93% at 5 years.
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4. Discussion
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Optimization of anticoagulation can reduce complications following mechanical heart valve replacement but other disadvantages remain: systolic flow reduction due to sewing ring and occluders as well as the necessity of lifelong anticoagulation with coumadin [14]. Despite initially high expectations in biological valve replacements (xenografts, homografts), structural degeneration limits their long-term performance significantly [15,16]. Thus, preservation of the own vital aortic valve has clear advantages and can be performed with encouraging results in patients with aortic root aneurysm. Of 48 patients operated in our institution between 1993 and 1998, 41 demonstrated excellent function of their native reimplanted valve. In 3 patients, moderate regurgitation occurred without hemodynamic relevance. Three other patients required reoperation for progressive valvular insufficiency. Detailed intraoperative analysis demonstrated that resuspension of the commissures was too low in two patients leading to cusp prolapse. One patient with inflammatory disease (morbus Wegener) had thickened and shrunken leaflets with histologic evidence of inflammatory reaction in valve cusps. Modification of surgical technique and exclusion of patients with inflammatory disease have abolished the necessity for reoperation during the last 3 years. Thromboembolic and bleeding complications after the perioperative period were not observed. These results confirm our own early experience as well as reports published by David et al. and Simon et al. [17–19]. Low perioperative morbidity and mortality as well as stable function of the reconstruction during the observation period should be pointed out in our series.
Additionally to the aortic valve preservation technique used in our patients, an alternative surgical strategy for modification of the sinotubular junction in such patients has been reported by Sarsam and Yacoub [20]. Contrary to resuspension of the aortic valve within a prosthesis, their technique focuses on resection of the aortic sinus with isolated correction of the sinotubular junction. This minimizes the risk of cusp contact with the prosthetic wall and potentially preserves the dynamic function of the aortic root. Critical arguments for us to proceed with David's method were the more radical resection of the diseased aortic wall as well as routine annular stabilization. Long-term results will be necessary to allow final judgement between the two procedures. Thus far we have not observed any morphological or functional degeneration of aortic valve cusps (Fig. 4)
. Despite these favorable initial results with valve preserving aortic root replacement specific questions remain in the management of patients with Marfan's syndrome. Increasing diameters of the ascending aorta carry an elevated risk for acute aortic dissection. Elective replacement of the aortic root and ascending aorta with a valved conduit significantly improved survival in these patients [21]. It is yet unknown to what extent the structural fibrillin defect (resulting from mutation of the fibrillin gene) can affect stability and durability of valve reconstruction. Recently published data confirm fibrillin deficiency in aortic cusps of patients with Marfan's syndrome, as well as a significant valve deterioration in patients with advanced disease [22]. This is in contrast to the intraoperative aspect in early disease stages and to the excellent results of valve preservation in this patient group [23]. Furthermore, risk of dissection in other aortic areas with necessity of a second or third operation makes patient management more difficult, when continuous anticoagulation is necessary. Considering these aspects, we would clearly favor this valve preserving operation in patients with Marfan's syndrome without macroscopic valve degeneration.
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Fig. 4. Transthoracic echocardiography 58 months after valve reimplantation without cusp degeneration and no valve insufficiency.
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A significant limitation of our technique is the short observation period. Longest follow-up in our patients is 5 years and meanwhile more than 9 years in the Toronto group. Significant degenerative changes in biological valves usually occur after 10 years. Therefore, continuing critical evaluation of this technique with carefully documented patient follow-up is necessary to allow further judgment of risk and benefit for patients undergoing aortic root surgery. Whether it is safe to use this technique in patients with bicuspid valves and thin and pliable leaflets is yet unknown. In our opinion, selected patients most likely could benefit from this procedure if excellent initial coaptation of cusps can be achieved.
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5. Conclusion
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Our results demonstrate that valve preserving aortic root surgery with this innovative technique represents a true alternative to composite graft implantation. Low perioperative morbidity and mortality as well as lack of anticoagulation and excellent hemodynamics encourage further use of this repair. Yet, final judgment of the long-term durability of this surgical technique will require further studies.
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Footnotes
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Presented at the 12th Annual Meeting of the European Association for Cardio-thoracic Surgery, Brussels, Belgium, 20–23 September, 1998.
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Appendix A. Conference discussion
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Dr Westaby (Oxford, UK): You did not say whether the three reoperations were in patients with Marfan's syndrome. Were they Marfan's patients or were they not?
Dr Harringer: One of them was. So far all other Marfan patients did very well.
Dr Westaby: So currently you think this is a good operation in Marfan's syndrome?
Dr Harringer: With our current experience, limited by a 5 year follow-up period, we consider this operation ideal for Marfan patients. Further time is necessary to evaluate whether fibrillin deficiency in aortic cusps will alter the longevity of the repair.
Dr Westaby: Do you have any ideas from the preoperative investigations as to which patients to select? You have a way of looking at them postoperatively, but do you have any predictors from the preoperative investigations to suggest which patients will do well and which will not?
Dr Harringer: We have a cardiologist who is very much interested in the preoperative identification of these patients. Cusp thickening and calcification on echocardiography reduces the chances for a valve repair. But so far the real decision to preserve the valve or not is finally done in the operating theater and has been always successfully accomplished.
Dr Velebit (Geneva, Switzerland): I found it rather difficult to judge on the height of the incision of the prosthesis when you make the cloverleaf incision for the commissures.
Dr Antunes (Coimbra, Portugal): There is no incision on the prosthesis, is there?
Dr Harringer: There is no incision on the prosthesis. The prosthesis is fixed subannularly, and the valve is resuspended.
Dr Velebit: That is not quite the operation that Tirone David described because he makes three incisions in the prosthesis.
Dr Harringer: The operation we performed is the classical technique described first by David and Feindel in 1992. To the best of my knowledge Tirone David has modified his technique now towards a combination of aortic remodeling (described by Sarsam and Yacoub) with additional annular stabilization.
Dr La Francesca (Rome, Italy): Actually that brings me to the question, how would you compare this procedure to the new Tirone David or Yacoub procedure? Because I was under the impression that actually everybody is switching to this operation.
Dr Harringer: The reason why we stuck to this type of operation is simply because we wanted to further evaluate this technique in a larger number of patients. The advantage, in our opinion, is that you stabilize the whole aortic root area and that you have a very standardized approach in doing this. One point of criticism is the reduced flexibility of the aortic root with the classical technique. There is some evidence that this might be true compared to the Yacoub technique. How additional stabilization of the annulus alters root flexibility and if there is any difference to reimplantation of the valve inside a prosthesis is yet unknown. Whether routine stabilization of the annulus is necessary remains controversial; we like to have all potentially diseased tissue excluded. The second point of criticism is that aortic cusps will deteriorate faster due to contact with the prosthetic wall. To my knowledge this is hypothetical and has not yet been proven. So far, we have not observed any structural changes of aortic cusps on echocardiography in our patients. Duration and ease of valve repair will determine in the future which technique is best for which indication.
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Abstract
1. Introduction
