Asian Cardiovasc Thorac Ann 2002;10:137-140
© 2002 Asia Publishing EXchange Pte Ltd
Total Reconstruction of the Mitral Valve With Autopericardium: Anatomical Study
Vahe C Gasparyan, MD,
Van S Galstyan, MD
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Department of Cardiovascular Surgery Mikaelian Surgical Institute Yerevan, Republic of Armenia
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Vahe C Gasparyan, MD Tel: 65 6772 5214 Fax: 65 6776 6475 email: vahegasparyan{at}yahoo.com Department of Cardiac, Thoracic and Vascular Surgery, National University Hospital, 5 Lower Kent Ridge Road, Level 2 Linkway Main and Kent Ridge Wing, Singapore 119074, Republic of Singapore.
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ABSTRACT
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Mitral valve repair has several advantages over prosthetic valve replacement. A new technique of total reconstruction of the mitral valve with autologous pericardium is described. The native mitral valve leaflets and chordae were excised from 10 human cadaver hearts, in the same way as for prosthetic valve replacement. The dimensions of the physiologically normal mitral valve were used to calculate the parameters for tailoring a corresponding new valve. Autologous pericardium was fixed in 0.625% glutaraldehyde solution for 10 minutes. The calculated parameters of the mitral valve were marked on the pericardium. The new valve was fashioned and inserted in the native valve position. Hydraulic probes showed good competence in all 10 reconstructed mitral valves. This method might be a good alternative to prosthetic valve replacement.
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INTRODUCTION
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Mitral valve (MV) repair procedures have stood the test of time with excellent function and proven durability.1–4 As operative techniques have become well standardized, the major issue remaining is the indication for repairing the valve in preference to replacing it. Unfortunately, severe shrinkage, deformation, and calcification of valvular tissue, especially in patients with rheumatic heart disease, can make valve repair impossible. Replacement of the MV with a mechanical or biological prosthesis has been the only solution in such cases. A new technique of total reconstruction of the MV with an autologous pericardial patch is described.
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MATERIALS AND METHODS
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The dimensions of the physiologically normal MV were used to determine parameters for reconstruction of the valve. The normal systolic orifice configuration of the MV has a characteristic 3:4 ratio of the anteroposterior (At) and transverse (Tr) diameters:5
 | [Equation 1] |
As ring selection is based on measurement of the surface area of the anterior leaflet after unfurling it, we can assume that the height of the anterior leaflet (H) is nearly equal to the anteroposterior diameter of the normal MV:1
 | [Equation 2] |
Substitution of equation [2]
into [1] yields the following:
 | [Equation 3] |
Since the transverse diameter of the MV corresponds to its intercommissural distance (l), the height of the anterior leaflet of the valve can be determined as:
 | [Equation 4] |
The height of the posterior leaflet (h) of the MV can be calculated from the height of its anterior leaflet using the normal 1:3 ratio:6
 | [Equation 5] |
Substitution of equation [5] into [4] yields:
 | [Equation 6] |
The posterior leaflet attachment (including the com-missural attachments) takes up two-thirds of the mitral annular circumference.7 So the length of the mural leaflet attachment (including the commissural attachments) is approximately twice the length of the anterior leaflet attachment.7 As the attachment length of the anterior leaflet is practically the same as the intercommissural distance (l), so the length of the posterior leaflet attachment including the commissural attachments (L) can be calculated as:
 | [Equation 7] |
The annulus-papillary muscle distances of the mitral apparatus are similar in the 2-, 4-, 8-, and 10-o':clock positions and correlate with the mitral annular diameter.7 Each distance is significantly longer than the corres-ponding chordae tendineae which are approximately half the anterior leaflet attachment length, i.e., the inter-commissural distance (l).7 Thus, the length of the chordae tendineae in the 2-, 4-, 8-, and 10-o':clock positions (X) can be calculated as:
 | [Equation 8] |
Total reconstruction of the MV with autologous peri-cardium was performed in 10 consecutive human cadaver hearts from 6 men and 4 women. The cadavers were conserved at low temperature before the study. Mean age was 63.8 years (range, 51 to 74 years), mean weight was 62.8 ± 10.14 kg, and mean height was 171 ± 7.7 cm. Two commissural mattress sutures were placed through the annulus to mark its commissural zones. The native MV leaflets and chordae were excised in the same way as during prosthetic valve replacement. After traction was established on the two commissural stitches, sizers were used to measure the intercommissural distance of the annulus. Various sizers were tried and one with an intercommissural distance (between the two notches) corresponding to that of the annulus was selected. The MV parameters were determined using equations [4], [6], [7], and [8]. The intercommissural distances and the calculated parameters of each MV are summarized in Table 1
. Autologous pericardium was harvested and fixed in 0.625% glutaraldehyde solution for 10 minutes.8,9 The determined parameters of the MV were marked on the pericardium and it was fashioned as shown in Figure 1. To obtain the curvature of the native anterior leaflet attachment, a mark was made at one-fifth of the leaflet height above the midpoint of the intercommissural distance (Figure 1). Thus, the radius (R) of the anterior leaflet coaptation edge is equal to four-fifths of the leaflet height (Figure 1). The pericardium was tailored along the marked line, leaving 2 to 3 mm of tissue for the sutures along the leaflet attachment (dashed line on Figure 1). The reconstructed valve was inserted in the native valve position. The flaps Z1 and Z2 were sutured to both sides of the anterolateral papillary muscle head, and the flaps Z3 and Z4 were sutured to both sides of the posteromedial papillary muscle head, using two horizontal mattress sutures of 4/0 Prolene (Ethicon, Inc., Somerville, NJ, USA). The commissural zones of the patch were sutured to the corresponding parts of the fibrous annulus, and the leaflets were sutured to the annulus along the attachment line, using continuous sutures of 5/0 Prolene. The continuity of the mural leaflet was restored with interrupted sutures of 5/0 Prolene. The final view of the newly created MV is shown in Figure 2. The competence of the recon-structed valve was checked with a hydraulic probe. The aortic root was clamped just above the valve. Water was injected through the MV into the left ventricle under pressure from a 250-mL bulb syringe. Direct manometry was used to measure the ventricular pressure during water injection.
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Figure 1. Marking the mitral valve parameters and fashioning the pericardium. H = height of the anterior leaflet, h = height of the posterior leaflet, K = commissural height (approximately 5 mm), L = length of the posterior leaflet attachment, l = intercommissural distance, R = radius of the anterior leaflet coaptation edge, Z(1,2,3,4) = papillary flaps.
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Figure 2. The final view of the totally reconstructed mitral valve. H = height of the anterior leaflet, h = height of the posterior leaflet.
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RESULTS
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The mean time required to manufacture each valve was 42.5 ± 3.75 minutes. The mean pericardial area of both leaflets was 11.04 ± 1.89 cm2. The hydraulic probes showed good competence of all 10 newly created MVs, and hermetic suture lines (Figure 3). The left ventricular pressure detected by hydraulic probe was equivalent to endsystolic pressure. The reconstructed valve leaflets were of good pliability and mobility, without any restriction.
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Figure 3. The hydraulic probe in the reconstructed mitral valve, showing good competence of the valve and a hermetic suture line.
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DISCUSSION
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Total reconstruction of a valve with autologous peri-cardium is now considered a possible alternative to prosthetic valve replacement. Different methods of total reconstruction of the aortic valve with autologous pericardium have been described, with good results.10,11 Our previous experimental studies were dedicated to this.12,13 Autopericardium, because of its ready availability, ease of handling, and low cost, has been used regularly since the early days of cardiac surgery. Pretreatment of the pericardium with glutaraldehyde reduces the risk of infective endocarditis.10 Moreover, the fixation of biological tissues in glutaraldehyde solution reduces antigenicity and improves both the physical and chemical characteristics of the tissue.8 It is believed that being stentless and nonantigenic, an autogenous pericardial valve should perform better than a standard bioprosthesis.10 Valve reconstruction with autopericardium has several advantages over prosthetic valve replacement, including lower risks of thromboembolism, hemorrhage, valve degeneration, and septic endocarditis. This is of special interest in patients who are young, those desiring pregnancy, those who live in remote areas with problems of poor drug compliance, and in cases where long-term anti-coagulation is contraindicated.11
So far, there have been no reports of total reconstruction of the MV with autopericardium. The two main essential factors to be considered in this respect are the need for a standard surgical technique to ensure a correct, reproducible, and safe result, and the long-term durability of the selected material. The key factor in total reconstruction of the MV with autopericardium is accurate determination of the parameters for fashioning the leaflets and restoring the normal physiologic 3:4 ratio of the anteroposterior and transverse diameters of the annulus. Leaflet shrinkage makes direct measurement of the leaflets impossible during the operation. The method described herein allows the determination of all parameters of the MV leaflets and chordae, without their direct measurement during the operation, using only the intercommissural distance which can be easily measured after excision of the diseased valve. The intercommissural distance of the MV corresponds to the aorto-mitral fibrous membrane which is rigid and not likely to dilate, whereas under pathological conditions, the remaining part of the annulus may dilate. So the intercommissural distance of the MV precisely reflects the normal dimensions of the valve, even if annular dilation is evident. It is essential also to restore the normal systolic configuration of the mitral annulus after completion of valve reconstruction, if annular dilation is evident. It can be easily performed by ring implantation. The size of the ring must correspond to the intercommissural distance. There was no incidence of annular dilation in this study.
The obvious advantage of the described method over prosthetic valve replacement is the maintenance of continuity between the mitral annulus and the papillary muscle, which has a beneficial effect on left ventricular postoperative performance. It was concluded that this method of total reconstruction of the MV with auto-pericardium has the additional advantages of being accurate, easy to perform, stentless, nonantigenic, anatomical, and cost-effective. It is recommended that this technique should be tested in animal experiments with a view to clinical application in the future, since the good durability of autopericardium has been established.10,11 It is hoped that this technique might be a good alternative to prosthetic MV replacement, especially in patients who are young, those desiring pregnancy, and in cases where long-term anticoagulation is contraindicated. We intend to conduct studies in animals to evaluate the function of the reconstructed valves using echocardiography, and we look forward to collaborating with other enthusiasts in this endeavor.
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ABSTRACT
INTRODUCTION
