| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Ann Thorac Surg 2007;83:958-963
© 2007 The Society of Thoracic Surgeons
Day General Hospital, Tehran, Iran
Accepted for publication August 28, 2006.
* Address correspondence to Dr Roshanali, 15th Tower, 8th Floor, No. 1, Hormozan St, Ghods Shahrak, Tehran 14466, Iran (Email: farideh_roshanali{at}yahoo.com).
 |
Abstract |
|---|
 Top Abstract IntroductionPatients and MethodsResultsCommentReferences |
|---|
Methods: One hundred patients with ejection fraction less than 40, who were candidates for isolated surgical correction of mitral insufficiency, had mitral valve replacement and were prospectively randomly assigned to either total chordal-sparing or papillary muscle repositioning. Fifty subjects underwent papillary muscle repositioning (PMR group), and the remaining 50 had complete preservation of all chordal structures with mitral valve replacement (CMVR group). Echocardiography was performed preoperatively, at discharge, and after 2 years to determine dimensions, left ventricular shape, and function.
Results: End-diastolic and -systolic volumes decreased in both groups initially and continued to decline. Decreasing volumes, however, were more significant in the PMR group, in which the significant decrease in the sphericity index continued for another 2 years. In contrast, the sphericity index in the CMVR group had no significant changes at discharge and at 2 years. In terms of systolic performance, ejection fraction had no significant changes in the CMVR group, whereas ejection fraction significantly increased in the PMR group.
Conclusions: Papillary muscle repositioning may result in more favorable left ventricular remodeling compared with complete retention of the mitral subvalvular apparatus during mitral valve replacement. It confers a significant early and late advantage by causing significant reductions in the left ventricular chamber volume, sphericity index, and systolic performance.
|
Introduction |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsCommentReferences |
|---|
Echocardiographic preoperative ejection fraction and systolic diameter can be predictive of postoperative ejection fraction [3]. After surgical correction of mitral regurgitation, left ventricular dysfunction is frequent and carries a poor prognosis.
We introduce a new papillary muscle repositioning technique for subvalvular-sparing mitral valve replacement procedures in an left ventricular dysfunction population and evaluate the early and late effects of this procedure on clinical outcome and left ventricular mechanics.
|
Patients and Methods |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsCommentReferences |
|---|
Mitral valve involvement in our subjects was, in order of frequency, degenerative (myxomatous and nonmyxomatous, n = 81) or rheumatic (n = 19) disease (Table 1). Random allocation of the patients to either the CMVR or PMR group was dependent upon the surgeon’s intraoperative decision to perform mitral valve replacement; the surgical ward secretary, having already been given 100 envelopes numbered from 1 to 100—the even numbers for CMVR and the odd numbers for PMR—would then give the surgeon one of these numbers at random. Fifty of these subjects underwent complete chordal preservation (CMVR group), and 50 had papillary muscle repositioning (PMR) for preservation of the mitral subvalvular apparatus. All the patients had an ejection fraction of less than 40%, and all the valves were deemed to be irreparable at the time of surgery by the surgeon. Our exclusion criteria were ischemic mitral regurgitation (to avoid interference between our results and those of coronary complications), evidence of coronary artery disease, substantial mitral stenosis (mean transvalvular gradient > 5 mm Hg), and need for other surgical procedures. Informed consent was obtained from all the patients, and the protocol was approved by our Review Board.
|
Although preoperative echocardiography was indicative of the irreparability of all the valves, the surgeon’s final intraoperative assessment of the valve would decide between mitral valve repair and replacement. In those patients having been randomly assigned to the complete chordal preservation group, the entire subvalvular apparatus was preserved in anatomic fashion. The posterior leaflet and its chordal attachments were preserved. If the posterior leaflet was excessively redundant or the chordae tendineae were elongated, the leaflet was imbricated into the mitral annulus with the valve sutures. The anterior leaflet was detached 3 to 4 mm from the annulus, and a central elliptical portion was excised, leaving a 5- to 8-mm rim of leaflet-free edge, which was attached to the primary (first order or marginal) chordae tendineae. This strip of the leaflet was then reattached to the annulus in the corresponding location with the valve sutures (Khonsari II technique). Alternatively, if the anterior leaflet was excessively redundant, it was divided into 2 to 4 segments, which were afterward resuspended in a normal anatomic position with the valve sutures (Khonsari I technique).
In the patients having been randomly allocated to the papillary muscle repositioning group, leaflets were excised from base (2 mm from annulus), and all of the native chordal structures were resected. Subsequently, the heads of both papillary muscles were sutured with a 2-0 Ethibond (Ethicon Inc, Somerville, NJ) to the posterior side of the corresponding annulus, leaving no space between the heads of the papillary muscles and the annulus. If the papillary muscle had fibrous tissue, a suture of 2-0 Ethiband on a double-armed needle was sewn to the fibrous tip. If there was no fibrous tissue, the suture was buttressed with a small soft felt pledget or pericardium and was tied snugly. Both needles of each suture were then passed through the annulus of the mitral valve at the roughly 4 and 8 o’clock positions. Finally, the valve was implanted on the annulus, so that the heads of the papillary muscles were directly underneath the ring of the prosthetic valve (Fig 1).
|
Transesophageal echocardiography examination was routinely done during the operations. Both leaflets of the prostheses were freely mobile without any limitation in all the patients. There was no left ventricular out flow tract obstruction or prosthesis-related complication in either group.
Echocardiographic Studies
Two-dimensional, M-mode, and color-flow Doppler echocardiography with standard acoustic windows using a GE Medical System (Vivid 7; General Electric, Horton, Norway) were performed in all the patients preoperatively (transthoracic echocardiography), intraoperatively (transesophageal echocardiography), and postoperatively (transthoracic echocardiography) first at hospital discharge and then 2 years afterward. Intraoperative echocardiographic measurements were made possible by maintaining an acceptable level of blood volume, blood pressure, and heart rate after our patients had been weaned off the bypass. Upon the completion of the study, all the results were read by two observers in a blinded fashion. Mean values for each measurement were derived from 3 consecutive heart beats in the patients in sinus rhythm and from 5 beats in those in atrial fibrillation. Of a total of 100 cases, we only had 5 patients lost to follow-up: 2 of them had died, and we lost track of the other 3.
Ejection fraction was computed by means of left ventricular end-diastolic and end-systolic volume, utilizing Simpson’s method.
The left ventricular sphericity index was calculated as the ratio of the left ventricular internal diameter in short axis compared with the left ventricular length (measured as the distance from the mitral annulus to the apical endocardium in the left ventricular long axis view).
Echocardiographic data were measured according to the criteria of the American Society of Echocardiography.
Statistical Analysis
Data are expressed as mean and standard deviation (SD). Data comparisons between the two groups were performed by unpaired t test. Longitudinal changes in the variables were compared between the two groups by two-way analysis of variance with repeated measurements.
All the statistical analyses were performed using the SPSS version 11.0 program (SPSS, Chicago, Illinois). A significance level of p less than 0.05 was used for all the comparisons.
|
Results |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsCommentReferences |
|---|
There was neither operative nor hospital mortality. However, 1 patient in the CMVR group died of trauma, and 1 patient in the PMR group died of pulmonary infection and respiratory failure 2 months after surgery. No bleeding and thrombosis or embolic complications were found over the follow-up period.
Cross-clamp period in the PMR group was no longer than that in conventional MVR operations. The mean aortic cross-clamp time was 30.0 ± 10 minutes in the CMVR group and 32.0 ± 12 minutes in the PMR group. The cardiopulmonary bypass time was 40 ± 11 minutes and 41 ± 14 minutes in the CMVR and PMR groups, respectively.
As regards ejection fraction (%), there was a sudden increase demonstrated by intraoperative transesophageal echocardiography in the PMR group from a preoperative 33.4 ± 5.2 to 40.20 ± 5.25, which was confirmed by the continuous slight increase in postoperative transthoracic echocardiography (42.5 ± 5) at discharge and 2 years afterward (44.9 ± 3.2). In the CMVR group, however, ejection fraction increased slightly from 33.1 ± 5.4 to 35.10 ± 4.34 intraoperatively; this trend continued from 35.7 ± 4.9 predischarge to 36.2 ± 4.4 after 2 years. It was noted that whereas ejection fraction had no significant changes in the CMVR group, it exhibited a significant increase in the PMR group (Fig 2).
|
The sphericity index significantly decreased initially, and this trend continued for 2 years. In contrast, the sphericity index in the CMVR group had no significant changes at discharge and after 2 years (Fig 5).
|
|
|
|
|
Comment |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsCommentReferences |
|---|
Despite this, ejection fraction is one of the most important determinants of long-term survival after mitral valve surgery for mitral regurgitation. Patients with normal preoperative ejection fraction have an excellent postoperative survival, whereas patients with moderate to severely reduced ejection fraction are at considerable risk [3–8].
Mitral valve surgery for the correction of mitral regurgitation in patients with left ventricular dysfunction has long been associated with a poor outcome, with numerous studies identifying a depressed left ventricular ejection fraction as a poor prognostic indicator [3–8]. These observations have been largely made in the case of traditional mitral valve replacement, causing the disruption of the subvalvular apparatus. Lillehei and colleagues [9] were the first to describe the importance of conservation of the subvalvular apparatus in the preservation of systolic function. The early [10–12] and late [13–15] hemodynamic benefits of preserving the mitral subvalvular apparatus during mitral valve replacement have been demonstrated in several studies.
Some studies, such as that by Okita and associates [16, 17], favor the replacing of chordae tendineae; however, we would suggest the complete removal of chordae tendineae.
The irreversible left ventricular changes in the wake of significant remodeling of the ventricle thwarted surgeons’ previous attempts at averting a decrease in ejection fraction by preserving the patient’s subvalvular apparatus, and that prompted us to demonstrate that our technique helps the left ventricle remodel to a smaller and more ellipsoid ventricle, with an increase in ejection fraction and decrease in the sphericity index postoperatively.
Our findings suggest that the repositioning of papillary muscles results in more favorable left ventricular geometry and its concomitant improvement in ventricular remodeling and ejection performance even at 2 years. We would, therefore, recommend that papillary muscle repositioning be performed if mitral valve replacement is necessary so that early postoperative and late left ventricular systolic functions can be optimized.
We maintain that not only is this management strategy important for patients with mitral regurgitation of a valvular etiology, but also it can be extended to mitral regurgitation of a ventricular etiology in patients with functional mitral regurgitation. As mitral regurgitation is commonly associated with dilated cardiomyopathy, PMR could be an integral part of the management of patients whose mitral valve is irreparable. This, we maintain, is achieved partly by the preservation of the subvalvular apparatus during replacement and partly by the correction of the volume overload in the left ventricle and better left ventricular shape, allowing a more gradual physiologic remodeling than that achieved by, for example, left ventriculectomy.
We conclude that our technique for reshaping the left ventricle during mitral valve replacement can be accomplished safely, with excellent results in patients with mitral regurgitation and left ventricular dysfunction. Table 2
|
|
References |
|---|
|
TopAbstractIntroductionPatients and MethodsResultsCommentReferences |
|---|
Related Article
This article has been cited by other articles:
|
|
 |
|
  D. Glower Invited commentary Ann. Thorac. Surg., March 1, 2007; 83(3): 963 - 963. [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
