Ann Thorac Surg 2006;81:1625-1631
© 2006 The Society of Thoracic Surgeons
Original article: Cardiovascular
Mitral Valve Repair for Anterior Leaflet Prolapse With Expanded Polytetrafluoroethylene Sutures
Hitoshi Kasegawa, MD
*
,
Tomoki Shimokawa, MD,
Ikuko Shibazaki, MD,
Hiroki Hayashi, MD,
Toshiya Koyanagi, MD,
Takao Ida, MD
Department of Cardiovascular Surgery, Sakakibara Heart Institute, Tokyo, Japan
Accepted for publication November 3, 2005.
* Address correspondence to Dr Kasegawa, Sakakibara Heart Institute, 3-16-1 Asahicho, Fuchu, Tokyo 183-0003, Japan (Email: zbn25716{at}nifty.com).
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Abstract
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BACKGROUND: This study was a long-term Doppler echocardiographic assessment of mitral valve repair for anterior mitral leaflet prolapse using expanded polytetrafluoroethylene sutures.
METHODS: Between April 1992 and December 2003, we performed mitral valve repair using expanded polytetrafluoroethylene sutures in 204 patients (mean age, 54.6 years) with severe mitral regurgitation (MR) having anterior mitral leaflet prolapse. The cause of valve disease was degenerative in 181 patients (88.7%). Postoperative serial transthoracic echocardiographic studies were performed in all hospital survivors. Residual MR flow detected by color Doppler echocardiography was classified according to the maximum regurgitant jet area.
RESULTS: The 30-day mortality of 204 patients was 1.4% (3 deaths). There were 12 late deaths and 14 reoperations in this series. Kaplan-Meier survival and freedom from reoperation at 12 years were 84.6% ± 4.0% and 89.9% ± 2.9%, respectively. Postoperative transthoracic echocardiographic assessment after discharge (mean follow-up, 4.2 ± 3.0 years) showed less than mild regurgitation (maximum regurgitant jet area < 4.0 cm2) in 80.9% of the patients. Overall, freedom from severe MR (maximum regurgitant jet area 
7.0 cm2) estimates at 12 years were 88.1% ± 3.1%. Freedom from severe MR at 12 years for 114 patients with no MR (maximum regurgitant jet area = 0 cm2) on intraoperative transesophageal echocardiography and 77 patients with MR was 95.3% ± 2.1% and 82.9% ± 5.1%, respectively (p = 0.033).
CONCLUSIONS: Twelve-year echocardiographic follow-up demonstrates good long-term results of chordal replacement with expanded polytetrafluoroethylene sutures for anterior mitral leaflet prolapse. To avoid recurrence of regurgitation, a significantly high level of competence of the valve is essential in the repair of anterior mitral leaflet prolapse.
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Introduction
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In recent years, mitral valve (MV) repair has become the standard surgical procedure for MV regurgitation, owing to the various merits of MV repair compared with MV replacement [1–3]. However, valve repair for anterior mitral leaflet (AML) prolapse is considered technically demanding and is performed less commonly compared with valve repair for isolated posterior mitral leaflet (PML) prolapse [4, 5].
Chordal replacement with expanded polytetrafluoroethylene (ePTFE) has permitted repair of AML prolapse in many patients who would otherwise require MV replacement [6, 7]. The major advantage of this procedure is that it can be used irrespective of the extent, type, or degree of disease, which ensures high feasibility of repair.
A possible disadvantage of this procedure is the difficulty of determining the proper length of the artificial chordae. In 1992, we developed a simple method for determining the proper length of artificial chordae using small tourniquets [8]. This simple method, we believe, has high reproducibility, which is considered very important in valve reconstruction.
Although chordal replacement with ePTFE sutures is now an option for repairing AML prolapse [9–11], there is little information on the stability of this procedure as evaluated by Doppler echocardiographic study [12, 13]. The aim of the present study was to investigate the long-term outcome of this procedure, focusing on the Doppler echocardiographic evaluation.
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Material and Methods
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Patients
Among 236 consecutive patients with severe mitral regurgitation (MR) having AML prolapse who underwent MV surgery in our institute between April 1992 and December 2003, MV repair using chordal replacement with ePTFE sutures was indicated and performed in 219 patients (indication rate, 92.8%). Excluding 15 patients (6.8%) in whom conversion to valve replacement during the same operation was needed mostly as a result of an intraoperative finding of advanced pathologic change, 204 patients who underwent MV repair using chordal replacement with ePTFE sutures were studied (accomplished rate of repair, 93.2%). There were 139 men and 65 women. The patients' ages ranged from 17 to 77 years (mean age, 54.6 ± 12.0 years). The preoperative electrocardiogram revealed sinus rhythm in 138 patients (67.6%) and atrial fibrillation in 66 patients. Table 1
summarizes the clinical data on these patients. The cause of valve disease was degenerative in 181 patients (88.7%; Table 2). Chordal rupture of the anterior leaflet was found in 69 patients (33.8%), and PML prolapse was associated in 102 cases (50.0%). Informed consent was obtained from all patients. The Institutional Review Board approved this study September 13, 2005.
Operative Approach and Surgical Procedure
Standard cardiopulmonary bypass techniques included bicaval cannulation and mild systemic hypothermia (35°C) to normothermia. Myocardial protection was achieved with antegrade intermittent cold blood cardioplegia and retrograde terminal warm blood cardioplegia. A combined transseptal superior approach was used in 191 patients (93.6%) and a right-sided left atriotomy in 13 patients.
The surgical procedures used are listed in Table 3. The techniques used for valve repair included chordal replacement with ePTFE sutures for the AML in all cases and quadrangular resection of the PML in 102 patients (50.0%) who had associated mural leaflet prolapse. In 10 patients, resection of a part of the AML was needed. In 11 patients with extended prolapse of the PML, chordal replacement with ePTFE sutures was added to the PML resection.
For mitral annuloplasty, we used the Carpentier-Edwards Classic annuloplasty ring (Edwards Lifesciences Inc, Irvine, CA) in 56 patients (27.5%) and Carpentier-Edwards Physio annuloplasty ring (Edwards Lifesciences Inc) in 42 patients (20.6%). Posterior annuloplasty was performed in 82 patients, of whom 60 patients (29.4%) were operated on using part of a flexible Duran Annuloplasty ring (Medtronic Inc, Minneapolis, MN) and 32 patients (15.7%) received autologous pericardium.
Chordal Replacement Using Expanded Polytetrafluoroethylene Sutures
A pair of ePTFE sutures is passed through a small pledget and tied on one side of the pledget. Double-armed mattress stitches on the side without a knot are passed through the head of the papillary muscle and another small pledget and are tied down. By this simple technique, two pairs of artificial chordae are made (Fig 1). Both ends of the sutures are then passed through the free margin of the prolapsed part of the leaflet, entering through the area where the native chord is attached, and are tied together (Fig 2).
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Fig 1. Chordal replacement using expanded polytetrafluoroethylene (ePTFE) sutures. A pair of expanded polytetrafluoroethylene sutures are passed through a small pledget and are tied on one side of the pledget. Double-armed mattress stitches on the side without a knot are passed through the head of the papillary muscle and another small pledget and are tied down. By this simple technique, two pairs of artificial chordae are made. Both ends of the sutures are then passed through the free margin of the prolapsed part of the leaflet and are tied together.
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Fig 2. Chordal replacement using expanded polytetrafluoroethylene (ePTFE) sutures. Both ends of the sutures are passed through the free margin of the prolapsed part of the leaflet, entering them through the area where the native chord is attached, and are tied together (A). The suture should be passed through the leaflet so that the knot is under the zone of coaptation (B, C).
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After a ring or band is implanted, the length of the artificial chordae was determined during the leak test using a small tourniquet in all cases. Placing the ring or band before determining the length of artificial chordae facilitates determination of the length of the artificial chordae [8, 14]. One purpose of the ring annuloplasty is to enlarge the area of coaptation. Thus it is difficult to decide the proper length of the artificial chordae during the leak test before annuloplasty. It would be quite difficult for patients with a huge dilated annulus because a substantial amount of leak would occur under such a condition (Fig 3). Once the competence of the valve is confirmed, the ePTFE sutures are held with a curved hemostatic forceps, and both ends of the stitches are tied gently to prevent them from slipping.
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Fig 3. Chordal replacement using expanded polytetrafluoroethylene (ePTFE) sutures. After a ring or band is implanted, the length of the artificial chordae was determined during the leak test using a small tourniquet. Placing the ring or band before determining the length of artificial chordae facilitates determination of the length of the artificial chordae.
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Intraoperative Doppler Echocardiographic Analysis
Transesophageal color flow mapping studies were performed in 190 patients (97.9%) immediately after discontinuation of cardiopulmonary bypass. Mitral regurgitation was quantified by direct planimetry of the maximum regurgitant jet area (MRA), which correlates well with angiographic quantification of MR [15]. The mosaic pattern was measured by planimetry to determine flow area, and extraneous color assumed to be caused by low-velocity swirling of flow in the left atrium was not measured. Depending on the area (MRA) and length of the mosaic, we decided whether a second pump run and intraoperative redo was necessary. From 1993, intraoperative redo was conducted when MRA exceeded 2.0 cm2. More recently, intraoperative redo was sometimes performed to reduce MR even when MRA was less than 2.0 cm2, especially for those patients with AML prolapse.
Echocardiographic Follow-Up
Early postoperative transthoracic echocardiography was performed before discharge. After discharge, transthoracic echocardiography was performed repeatedly on follow-up (average, 4.2 ± 3.0 years postoperatively; range, 0.2 to 12.0 years). The degree of residual MR was classified according to MRA. Trivial regurgitation is defined as MRA less than 2.0 cm2, mild regurgitation, as MRA equal to or more than 2.0 cm2 and less than 4.0 cm2, moderate regurgitation as MRA equal to or more than 4.0 cm2 and less than 7.0 cm2, and severe regurgitation as MRA equal to or more than 7.0 cm2.
Statistical Analysis
Demographics of the patients and outcome variables were expressed either as a percentage of the total or as mean ± standard deviation. All statistical analysis was performed using SPSS 10.0 statistical software for Windows (SPSS Inc, Chicago, IL). Survival, freedom from reoperation, and freedom from severe MR were analyzed with Kaplan-Meier actuarial methods.
Univariate logistic regression was used to identify several factors associated with recurrence of MR. Three factors with p less than 0.10 were entered into the stepwise multivariable logistic regression analysis to define independent risk factors for recurrence of MR.
Comparison among groups was done according to the log-rank method. A p value of less than 0.05 was considered to be statistically significant.
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Results
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Follow-Up
One hundred ninety-nine patients were discharged from the hospital. Follow-up was closed in May 2004. None of the patients were lost to follow-up. The mean follow-up period was 65.0 months (5.42 years), for a total of 1,084.9 patient-years. Range of follow-up was 0.41 to 12.1 years.
Surgical Outcome
There were three early deaths. The 30-day mortality was 1.9%. Two early deaths were attributable to severe infection and one was attributable to multiple-organ failure occurring in an elderly patient with liver cirrhosis. There were two other in-hospital deaths in elderly patients attributable to pneumonia 79 and 89 days after the operation.
Early complications included two events of systolic anterior movement, and five thromboembolic events (three had permanent neurologic deficit). There were no reoperations in the early postoperative stage. In the late postoperative period, thromboembolic complications occurred in 13 patients (2.0%/patient-years): 7 had permanent neurologic deficit. Infective endocarditis occurred in only 2 patients. There were no permanent pacemaker implantations (Table 4).
A total of 14 reoperations (2.2%/patient-years) were performed in the late postoperative stage in this series. The reasons for reoperation were recurrence of severe MR in 13 patients in whom MV replacement was performed, and hemolysis in 1 patient who underwent successful repeat valve repair 7 months after the initial operation. None of these reoperations were related to failure of the artificial chordae. There were 13 late deaths. The causes of late death were malignancy in 3 patients, cerebral infarction in 4, pneumonia in 3, and unknown in 2. Kaplan-Meier survival and freedom from reoperation at 12 years were 84.6% and 89.9%, respectively (Figs 4, 5).
Echocardiographic Data
Intraoperative MRA of 190 patients (97.9%) among 194 patients who received intraoperative transesophageal echocardiographic (TEE) evaluation was less than 2.0 cm2. Table 5
shows the postoperative transthoracic echocardiography of the patients. Transthoracic echocardiography assessment at discharge revealed that 97% of the patients had less than mild regurgitation. Late postoperative data (mean follow-up, 4.2 years) showed that regurgitation was mild or less in 87.1% of the patients, whereas the MRA was greater than 4.0 cm2 in 12.9% of patients. Overall, freedom from severe MR at 12 years was 88.1% ± 3.1% (Fig 6), and freedom from severe MR at 12 years for 114 patients with no MR (MRA = 0) on intraoperative TEE and 77 patients with MR was 95.3% ± 2.1% and 82.9% ± 5.1%, respectively (p = 0.033; Fig 7).
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Fig 6. Actuarial freedom from severe mitral regurgitation (MR). Overall, freedom from severe mitral regurgitation (maximum regurgitant jet area 7.0 cm2) estimate at 12 years was 88.1% ± 3.1%.
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Fig 7. Actuarial freedom from severe mitral regurgitation (MR). Freedom from severe mitral regurgitation at 12 years for 114 patients with no mitral regurgitation (maximum regurgitant jet area = 0 cm2) on intraoperative transesophageal echocardiography and 77 patients with mitral regurgitation was 95.3% ± 2.1% and 82.9% ± 5.1%, respectively (p = 0.033).
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As shown in Table 6, no factors were identified as risk factors for recurrent MR by multivariate analysis.
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Comment
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Mitral valve repair for MR has been evaluated as successful when long-term postoperative follow-up shows survival and no reoperation. Many reports have concluded favorable outcome of MV repair based on high survival rate and high reoperation-free rate in long-term follow-up. However, by conducting long-term repeat echocardiography after surgery, we have come to know that mild residual regurgitation that is present immediately after surgery tends to increase in intensity along with the improvement of wall motion, especially in cases of AML prolapse. Furthermore, when residual mild MR progresses very slowly for years after valve repair, heart failure symptoms do not manifest readily as a result of compensatory mechanisms, and it is possible for patients to have severe MR before surgical intervention is needed. Also patients do not favor reoperation when there are no subjective symptoms. Therefore, one may speculate that some of those patients who are reoperation-free in fact have moderate or severe MR. Patients with moderate or severe MR do not have a high quality of life, and the incidence of cardiac events in these patients is expected to increase. Long-term outcome of valve repair should be evaluated by detailed echocardiography, and the degree of regurgitation should also be assessed objectively.
In the present study, we evaluated the long-term outcome of valve repair in cases of AML prolapse by conducting Doppler echocardiographic assessment in all surviving patients at least once after discharge, using MRA as an indicator. Although MRA is not perfect as an indicator of regurgitant volume, it is useful to evaluate postoperative residual regurgitation after valve repair [16]. In this study, intraoperative MRA of 190 patients (97.9%) among 194 patients who received intraoperative TEE evaluation was less than 2.0 cm2.
Furthermore, postoperative transthoracic echocardiography study at discharge revealed 94% of the patients had less than mild regurgitation. However, late postoperatively, 85% of the patients were mild or less and 15% of all patients were moderate or severe. These data suggest that mild residual regurgitation that is present immediately after surgery tends to increase in intensity along with alteration of wall motion or remodeling of the left ventricle in patients with AML prolapse.
However, those patients with no MR on intraoperative TEE showed excellent results on late postoperative transthoracic echocardiography. This represented a significant difference compared with those patients with MR. This result strongly suggests the importance of complete repair for anterior leaflet prolapse.
Chordal replacement with ePTFE sutures has technical simplicity to ensure high predictability and high reproducibility and is associated with excellent repair durability [9–13]. Although triangular resection of the anterior leaflet is sometimes performed for those patients with segmental prolapse of the AML with excess tissue [17], it is not applicable to an extended area of prolapse [18]. There are three techniques frequently used to repair prolapse of the AML: chordal shortening [19], chordal transfer [20], and edge-to-edge repair [21]. There is a concern about durability of the shortened chordae. There are several reports showing high incidence of recurrence of chordal elongation after MV repair using chordal shortening [5, 10, 22]. Smedira and associates [23] reported better results in chordal transfer than in chordal shortening. However, we cannot know which chordae can be used for transfer before the operation. We believe chordal replacement has a higher predictability of results of repair than the former two techniques. Edge-to-edge repair can be an alternative to repair prolapse of the AML with high predictability.
David and colleagues [9] reported good long-term results of MV repair using chordal replacement of ePTFE, with a rate of freedom from reoperation of 94% at 10 years. They also demonstrated good long-term Doppler echocardiographic results of the group including isolated PML prolapse with a rate of freedom from recurrent severe MR of 93% at 10 years. In this study, freedom from severe MR at 12 years was 88.1%. Our indication rate of valve repair for AML prolapse is extremely high (92.8%). So our series may include many patients who may otherwise have been excluded for indication for valve repair. This may be one reason for the relatively higher rate of recurrent severe MR in our series. Of the 14 patients in whom conversion to valve replacement during the same operation was done, 3 were rheumatic cases and 3 were re-repair cases. In 9 of the 14, a leak test showed good competence (no leak), and MV replacement was performed in the second or the third arrest after unexpected mild leakage was detected by TEE. In all of these 9 patients, TEE revealed that correction of the prolapse was successful and an appropriate zone of coaptation was achieved. However, unresolved MR resulting from complex or advanced lesions on the leaflets themselves led to valve replacement. We believe that the rate of technical failure of chordal replacement with ePTFE sutures for AML prolapse is very low.
Our excellent results of freedom from severe MR of 95.3% at 12 years for 114 patients with no MR (MRA = 0) on intraoperative TEE strongly suggest the importance of complete competence of the valve in the repair of AML prolapse. In MV repair for AML prolapse, annuloplasty is another key to attaining complete competence. Since 1996, according to the concept of the physiologic remodeling annuloplasty, which we developed [24], in those cases with a high or elongated anterior leaflet, we have been performing a band annuloplasty to adapt the shape of the AML using autologous pericardium or part of a Duran ring. This method is very useful to avoid systolic anterior movement caused by a long anterior leaflet, especially in those patients with a billowing valve with excess tissue on the leaflet.
Twelve-year echocardiographic follow-up demonstrates good long-term results of chordal replacement with ePTFE sutures for AML prolapse. To avoid recurrence of regurgitation, a significantly high level of competence of the valve is essential in the repair of AML prolapse.
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References
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Abstract
Introduction
