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J Thorac Cardiovasc Surg 2005;130:1265-1269
© 2005 The American Association for Thoracic Surgery
Surgery for Acquired Cardiovascular Disease |
a Cardiac Surgery, Cliniche Humanitas Gavazzeni, Bergamo, Italy
b Institute of Clinical Physiology of the National Council of Research, Pisa, Italy.
Received for publication December 17, 2004; revisions received July 5, 2005; accepted for publication July 19, 2005. * Address for reprints: Alberto Repossini, MD, Cliniche Humanitas Gavazzeni, Via Mauro Gavazzeni No. 21, 24125 Bergamo, Italy (Email: alberto.repossini{at}gavazzeni.it).
| Abstract |
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METHODS: Between February 2002 and August 2004, a total of 65 consecutive patients at our institution (48% male, mean age 69 ± 12 years) underwent aortic valve replacement with Pericarbon Freedom stentless bioprostheses implanted with a single suture line. Most recurrent etiology was senile degeneration (80%). Pericarbon Freedom 25-mm and 27-mm valves were the most frequently implanted. Thirty patients had concomitant procedures (mainly coronary artery bypass grafting, 16 patients). Overall crossclamp time was 76 ± 21 minutes.
RESULTS: All patients survived intervention. One patient died early of multiorgan failure (postoperative day 16). There were 4 early nonvalve-related complications and no late complications at a mean follow-up of 491 ± 270 days. Four patients showed trivial central prosthetic regurgitation at intraoperative transesophageal echocardiography; among these cases, only 1 was confirmed at 6-month transthoracic echocardiography. At postoperative echocardiographic assessment, mean pressure gradient for the 25- through 29-mm size group was 10.2 ± 7.1 mm Hg, and peak pressure gradient was 18.1 ± 12.3 mm Hg.
CONCLUSION: Our initial experience combined a well-established supra-annular implantation technique with the Pericarbon Freedom stentless bioprosthesis, a latest-generation pericardial stentless valve. The combination showed excellent results in terms of safety and reliability, although this technique required adequate experience. Clinical outcomes are similar to those obtained with other techniques, with satisfactory hemodynamic performance.
| Introduction |
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With this in mind, we investigated the use of the Pericarbon Freedom (PF) stentless bioprosthesis (Sorin Biomedica Cardio, Saluggia, Vercelli, Italy) with a simplified supra-annular implantation technique. The prosthesis, available since 1991, consists of cross-linked bovine pericardium and has been redesigned in 2000 with the addition of a posttreatment step aimed at removing aldehyde residues.
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The valve design includes pericardium only, which forms the leaflets and extends toward inflow and outflow to allow surgical suture placement.
The PF bioprosthesis is provided by the manufacturer with extra tissue, allowing intraoperative tailoring for adaptation to local anatomy and the surgeon's technique. The valve has been implanted with two suture lines (interrupted or continuous stitches on the inflow side and continuous stitches on the outflow side).
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The alternative singlesuture line technique allows correct supra-annular positioning of the prosthesis, avoiding any nonvalvular tissue in the outflow tract.
| Methods |
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Indications and Contraindications
The indications for the PF stentless for supra-annular implantation are as follows: (1) Elderly patients with symmetric aortic root and trileaflet valve-sinus anatomy are the ideal patients. (2) Patients older than 60 years are candidates for this valve. Younger patients wishing to avoid anticoagulation and a mechanical valve and those for whom a homograft is not available may be candidates. (3) Patients with active endocarditis without periannular abscesses are candidates. The single rare contraindication to the use of this technique is massive calcification of the aortic sinus wall and root, which makes the supra-annular suturing impossible.
In addition to the preceding, two particular features should also be taken into account. Bicuspid valve is not a real contraindication, although directly opposing coronary ostia (ie, 180°) may present a difficult orientation of the valve toward the coronary ostia. In case of concomitant aortic ectasia with dilatation of the sinotubular junction (>2 mm larger than the annulus), ascending aorta replacement is mandatory to avoid valve incompetence.
Study Population
Between February 2002 and August 2004, a total of 65 consecutive patients received the PF stentless valve with a singlesuture line implant technique for aortic valve replacement. All implantations were performed by a single surgeon (A.R.). The study comprised 31 male and 34 female patients ranging in age from 26 to 87 years (mean 69 ± 12 years). Informed consent was requested from the patients in all cases, according to the rules and regulations of the internal review board of our institution.
Preoperative and intraoperative transesophageal echocardiographic and postoperative echocardiographic analyses were carried out at 1 week after implantation and again at 6 months. In addition to the usual gradient measurements, effective orifice area was also calculated. Clinical status and both type and frequency of postoperative complications were evaluated on the basis of the revised guidelines.
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Mean follow-up was 491 ± 270 days (range 987-29 days). Completeness of the follow-up was 100%. Color Doppler echocardiography was performed with a Philips Sonos 5500 system (Philips Medical System, Eindhoven, The Netherlands) equipped with a 2.5- to 3.5-MHz transducer. Standard M-mode and 2-dimensional measurements were collected according to the criteria of the American Society of Echocardiography.
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All Doppler measurements were averaged for more than three cycles in patients with sinus rhythm or more than five cycles in those with atrial fibrillation.
The reasons for valve replacement are shown in Table 1. Concomitant surgery was performed in 30 cases (46%). The most common procedure was coronary artery bypass grafting in 16 patients (Table 2).
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| Results |
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Mean implantation time was 30 ± 8 minutes. Mean crossclamp times were 62 ± 18 minutes for patients without concomitant procedures and 76 ± 21 minutes overall.
Early morbidity included 4 patients (6.1%) with nonvalve-related complications: 1 pacemaker implantation in a patient with associated tricuspid repair, 2 renal or respiratory transient failures, and 1 transient low cardiac output syndrome necessitating intravenous inotropic support. One female patient, aged 67 years and with associated myocardial revascularization, had endocarditis with extensive periannular abscess 2 months after the operation. Nevertheless, no aortic regurgitation was present, and at reoperation the prosthesis was found to be firmly anchored to the aortic wall. The postoperative course was uneventful, as was the follow-up. No other late complications were reported at follow-up. No late deaths occurred.
Echocardiographic Analysis
Four patients had trivial central prosthetic regurgitation at intraoperative transesophageal echocardiography. Only 1 case was confirmed at 6-month echocardiographic examination.
Peak pressure transvalvular gradient related to the 25- through 29-mm size group (92.3% of the patient cohort) at 1 postoperative week was 18.1 ± 12.3 mm Hg. Mean aortic transvalvular gradients were 10.2 ± 7.1 mm Hg at 1 postoperative week and 8.0 ± 4.3 mm Hg at 6 months. Effective orifice area at 6 months was 2.14 ± 0.50 cm2. Mean pressure gradients and effective orifice areas for the 21- through 29-mm sizes are reported in Table 3.
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| Discussion |
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In clinical practice, the PF stentless valve is optimal for supra-annular implantation for virtually all patients who otherwise would be receiving a stented bioprosthesis. In our consecutive series, no patient was excluded for technical or anatomic reasons.
The supra-annular positioning with PF stentless bioprosthesis shows many advantages. The effective orifice area is maximized, allowing 100% orifice-annulus match and the implantation of the largest valve orifice available. The blood flow from the ventricle to the aorta is streamlined laminar, and the transvalvular gradients are as low as those of an allograft aortic valve. We report a mean gradient of 10.4 ± 5.6 mm Hg for a 25-mm valve (annulus diameter 23 mm) and an effective orifice area of 2.0 ± 0.5 cm2. For comparison, in a local retrospective cohort, the 25-mm valve, with two-suture technique, had a mean gradient of 12.1 ± 4.2 mm Hg and an effective orifice area of 1.9 ± 0.4 cm2.
In making a comparison between the two implantation techniques, it should be noted that for a given annular diameter, the supra-annular placement allows a size larger valve. Moreover selecting a valve a size larger than the host annulus maximizes the leaflet coaptation. The stress on the suture line is better absorbed, avoiding the chiseling effect that arises when the stentless valve is implanted in intra-annular position.
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Bovine pericardium is resistant and fully retains the sutures without any risk of tearing, as has been reported with the aortic porcine wall.
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In addition, it is smooth and thin and adapts well to the host tissue, minimizing the risks of perivalvular leaks. Leaks were not observed in any cases in our series.
Moreover, there is no valve tissue inside the annulus and in the outflow tract except the leaflets, which are supra-annularly anchored to the aortic wall. Trimming away all the prosthetic pericardial tissue of the inflow tract is important, because no tissue has to be fixed below the leaflets and a single continuous suture line is sufficient to anchor this valve into place.
Placement of the sutures below or through the annulus should be avoided, because intra-annular implantation could have a negative effect on transvalvular gradients. Deep, almost full-thickness bites of the host aortic wall are recommended to secure the valve into place. Deep, broad bites on the outflow pericardial strips are to be performed as well, close to the leaflet attachment and to the black assembling suture. In this way there should be virtually no potential space behind the commissural posts and no ledge underneath the leaflet from the ventricular aspect, with no projection of tissue into the orifice during systole.
The singlesuture line technique avoids any periprosthetic dead space between prosthetic valve and native aortic wall. Last but not least, a single continuous suture line is simple and quick, saving time, which is especially advantageous when concomitant cardiac procedures are required.
Our experience combines a well-established truly supra-annular implantation technique with a latest-generation pericardial stentless valve that is now available pretrimmed (Freedom Solo).
These early favorable results need to be borne out by longer and more comprehensive studies of larger groups.
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| References |
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