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Ann Thorac Surg 2001;71:S323-S326
© 2001 The Society of Thoracic Surgeons
a Cardiovascular Institute, University of Dresden, Dresden, Germany
Address reprint requests to Dr Schüler, Cardiovascular Institute, University of Dresden, Fetscherstrasse 76 D-01307 Dresden, Germany
e-mail: monika.weber.hkz_dd{at}t-online.de
Presented at the VIII International Symposium on Cardiac Bioprostheses, Cancun, Mexico, Nov 3–5, 2000.
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Abstract |
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 TopFootnotes Abstract IntroductionMaterial and methodsResultsCommentReferences |
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Methods. From March 1999 to October 2000, 12 patients (ages 71 ± 2 years) received the SJM-Quattro-MV. Six patients suffered from valvular stenosis and 6 patients from incompetence. Preoperatively, all patients were in New York Heart Association functional class III, with left ventricular ejection fraction amounts of 54% ± 17%.
Results. Eleven patients received a medium size SJM-Quattro-MV and one patient received a large size SJM-Quattro-MV. Cross-clamp time was 99.8 ± 4.9 minutes. Additional procedures were coronary artery bypass grafting (n = 3) and left atrial microwave ablation (n = 2). Postoperative mortality (n = 1) was procedure related. At follow-up of 11.6 ± 5.4 months, all patients were well, the transvalvular pressure gradient was 5.0 ± 1.4 mm Hg, and the effective orifice area 2.7 ± 0.2 cm2.
Conclusions. Our preliminary experiences with the SJM-Quattro-MV presented good clinical results and promoted an optimistic way of thinking about the further development of these valve prostheses.
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Introduction |
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TopFootnotesAbstractIntroductionMaterial and methodsResultsCommentReferences |
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The high risk of life-threatening hemorrhages associated with anticoagulation therapy, especially in elderly patients, is well known [2].
Therefore, a new treatment concept for this patient group is necessary. Intuitively, replacement with a bioprosthesis resembling native mitral valve anatomy may be best. A flexible annulus, a large opening area, sufficient coaptation, and a suspension at the papillary muscles to preserve the continuity between the left ventricle and the annulus are mandatory [3]. The SJM-Quattro-MV (St. Jude Medical, Inc, St. Paul, MN) is a chordally supported stentless bioprosthesis which was developed to these specifications [4, 5].
This is our initial report on the implantation of the quadrileaflet mitral valve, which includes 1-year of clinical outcome data.
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Material and methods |
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TopFootnotesAbstractIntroductionMaterial and methodsResultsCommentReferences |
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There were 10 women (83.3%) and 2 men (16.6%). The ages of the patients ranged from 64 to 78 years (71 ± 2 years). The predominant valve pathology was stenosis in 6 patients and incompetence in 6 patients. The valve disease etiology was rheumatic in 7 patients, chronic ischemic in 2 patients, and degenerative in 3 patients. The body mass index was 24 ± 1.2 kg/m2. The preoperative left ventricular ejection fraction was 54% ± 17%. Clinical classification revealed New York Heart Association functional class III. Preoperatively, 8 patients were in sinus rhythm and 4 patients had atrial fibrillation.
Postoperatively, the patients were evaluated at discharge and then at 6-month intervals. The mean follow-up was 11.6 ± 5.4 month. At the follow-up visits patients underwent a clinical evaluation with a 12-lead electrocardiogram and transthoracic echocardiography.
The quadrileaflet mitral valve (SJM-Quattro-MV) is a stentless bioprosthesis made of bovine pericardium with standard glutaraldehyde tanning and additional anticalcification treatment with polyol. The valve consists of a large anterior and posterior leaflet and two small commissural cusps. The leaflets have straight hinge lines to avoid the excessive flexion stress of stented prostheses. The annulus is made of a three-layer pericardium and serves as a flexible annuloplasty device as well. Chordal support consists of two papillary flaps that support the anterior and posterior cusps. The long-term durability and hemodynamics of the SJM-Quattro-MVs were tested in laboratory and animal studies [5].
Operations were performed using median sternotomy and routine cardiopulmonary bypass with systemic hypothermia (32° C), and cardioplegic arrest (Cardioplegin N solution, Köhler Chemie, Alsbach, Germany). Access to the mitral valve is obtained through a right atriotomy followed by a transseptal incision. The left atrial incision begins in the fossa ovalis of the atrial septum and extends vertically and superiorly where it joins the right atrial incision at the most superior portion of the atrial septum. From this point, the left atrial incision is extended to the superior dome of the left atrium underneath the ascending aorta. The diseased mitral valve is completely excised using a straight line between the two fibrous trigones.
The two trigones are reference points for the following two sizing procedures:
The first sizing procedure is shown in Figure 1. For the selection of a valve prosthesis of appropriate size, and for exact suture placement at the papillary flaps of the prosthesis and on the papillary muscles, it is necessary to measure the distance from the trigonum to the tip of the papillary muscle, and the distance from the tip to the head of the papillary muscle. Later, the suture for the papillary flap implantation is placed on the head of the papillary muscle at the distance previously measured from the tip. The exact level of suture placement on the papillary flaps of the prosthesis results from addition of the trigonum-tip and tip-head distances. To get an accurate distance for the suture measurement, the papillary muscles should not be pulled. If they are pulled in the arrested heart, then the measured distance is entirely dependent on the tension exerted on each muscle.
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In 2 patients, intraoperative microwave ablation for the treatment of atrial fibrillation was applied before implanting the SJM-Quattro-MVs. A special tool (Fidus Lynx; Lynx Surgical ablation device; AFX Inc, Fremont, CA) was used to produce the endocardial linear lesions in the left atrium according to the technique previously reported from our group [6]. The additional cross-clamp time was about 10 to 15 minutes. All patients received anticoagulation therapy for 3 months. Patients receive a low dose of sotalol therapy and electrical cardioversion in case of recurrence of atrial fibrillation.
Transthoracic examination was performed preoperatively, postoperatively prior to discharge, and at every follow-up visit. Intraoperatively, two-dimensional and three-dimensional transesophageal echocardiography was used for prostheses function examinations.
Mitral valve regurgitation was defined as the relation between the jet area and the left atrial size as follows: trivial (less than 10%), mild (10% to 20%), moderate (20% to 40%), or severe (more than 40%). The mitral valve orifice area was calculated using the pressure half-time method and the effective mitral valve orifice area was calculated using the continuity equation [7]. Transvalvular gradients were calculated from continuous-wave Doppler using the modified Bernouilli equation.
Results are expressed as mean ± standard deviation. Student’s t test was used to compare the variables, a p value less than 0.05 was considered significant. The postoperative valve-related morbidity and mortality were defined according to standard guidelines [8].
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Results |
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TopFootnotesAbstractIntroductionMaterial and methodsResultsCommentReferences |
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The SJM-Quattro-MV was implanted in 6 patients with predominant mitral valve stenosis and in 6 patients with mitral valve incompetence. A large valve (size 30 mm) was used in only 1 patient, and a medium valve (size 28 mm) was used in 11 patients. The distance between the trigone and the tip of the right papillary muscle was 24 ± 1.8 mm and between the trigone and the tip of the left papillary muscle was 24 ± 1.5 mm. The mean cardiopulmonary bypass time was 133 ± 10 minutes; the mean cross-clamp time was 99.8 ± 4.9 minutes.
Exposure through the transseptal approach was excellent in all patients, and valve implantation was uneventful. Reexploration for bleeding of a pericardial vessel had to be performed in 1 patient. At follow-up all patients with preoperative sinus rhythm had normal sinus rhythm postoperatively. Among the 4 patients who had preoperative atrial fibrillation, 1 patient converted to sinus rhythm 6 months postoperatively, 2 patients converted to sinus rhythm after microwave ablation, and 1 patient had persistent atrial fibrillation postoperatively. Patients received coumarin anticoagulation therapy for 3 months after microwave ablation and in case of atrial fibrillation. Six months postoperatively, New York Heart Association’s functional class was I or II, and 1 year after the operation, New York Heart Association’s functional class was 0 or I. Freedom of adverse events was 100%.
The intraoperative transesophageal echocardiography demonstrated excellent valve function in all patients, with only a trivial regurgitation related to the functional valve anatomy. The three-dimensional transesophageal echocardiography image of the closed valve prosthesis presents the papillary flaps of the SJM-Quattro-MV and their attachment to the papillary muscle, as well as the position of the flaps in the left ventricle. The transthoracic examinations showed normal function of the quadrileaflet mitral valves in all patients postoperatively and at the follow-up visits. The echocardiographic measurements are shown in Table 1. The postoperative left ventricular ejection fraction was 60% ± 4%. The valve orifice areas were larger using the pressure half-time method (2.9 ± 0.25 cm) [2] and smaller when measured with the continuity equation (2.7 ± 0.2 cm) [2]. The mean transvalvular pressure gradient was 5.0 ± 1.4 mm Hg, and the maximum transvalvular velocity was 1.7 ± 0.2 m/s. Eight patients had no mitral valve regurgitation, and 4 patients had nonsignificant regurgitation.
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Comment |
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TopFootnotesAbstractIntroductionMaterial and methodsResultsCommentReferences |
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Surgical experience is still required for successful implantation of the quadrileaflet mitral valve prosthesis. The right exposure is a key point of the operation. The transseptal approach offers an optimal exposure of the papillary muscles anatomy, which is essential for exact examination and measurement. The papillary muscle is a muscle without a perimysium. This delicate structure must be treated extremely carefully. In preparation for suture placement it should be possible to make a single pass of the needle in a straight line from back to front without manipulating the needle while it is in the muscle. The needle must be round bodied and large enough to be easily seen and pulled through without distortion. Before tying the knots, the papillary flap of the prosthesis must be gently pushed down over the sutures until it is in contact with the muscle so that all tension on the suture is through the knot. Careful evaluation of the papillary muscles anatomy is essential. Special care is mandatory in patients with coronary artery disease and previous myocardial infarction. A neutral position is recommended for the attachment of the papillary muscles to the papillary flaps of the prosthesis. A position of the papillary flaps attachment that is too high results in bulking of the leaflets and a position of attachment that is too low will make a complete coaptation of the leaflets impossible and can lead to more pressure on the annulus sutures or the papillary muscles. The large coaptation area of the prosthesis reduces the risk of valve incompetence. Nevertheless exact sizing is mandatory because oversizing of the annulus leads to a reduction of the transvalvular blood flow by excessive tissue.
The intraoperative times are somewhat longer than usual for mitral valve replacement, including the earlier patients in our experience, as well as 3 patients with additional coronary artery bypass grafting, and 2 patients with additional microwave ablation. Also the extended transseptal incision requires additional time to be performed. In our view, the excellent exposure justifies this additional time.
After SJM-Quattro-MV implantation, patients received anticoagulation only for the first 3 months in case of microwave ablation or persistent atrial fibrillation. The restoration of sinus rhythm by intraoperative microwave ablation had an additional benefit for the patients and should also be included as a modern concept of mitral valve disease treatment.
In our preliminary experiences, using stentless mitral valve prostheses presents an alternative to conventional valve replacement. This promising method represents only the first step towards future developments. The quadrileaflet mitral valve fulfills most criteria of an ideal mitral valve prosthesis, nevertheless, a longer follow-up and the inclusion of more patients are mandatory for a definitive statement regarding the indications for mitral valve replacement with a stentless bioprosthesis.
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Footnotes |
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TopFootnotesAbstractIntroductionMaterial and methodsResultsCommentReferences |
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References |
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TopFootnotesAbstractIntroductionMaterial and methodsResultsCommentReferences |
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This article has been cited by other articles:
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  T. Athanasiou, A. Cherian, and D. Ross The Ross II Procedure: Pulmonary Autograft in the Mitral Position Ann. Thorac. Surg., October 1, 2004; 78(4): 1489 - 1495. [Abstract] [Full Text] [PDF]
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 T. Gudbjartsson, S. Aranki, and L. H. Cohn Mechanical/Bioprosthetic Mitral Valve Replacement Card. Surg. Adult, January 1, 2003; 2(2003): 951 - 986. [Full Text]
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