Mitral valve replacement with maintenance of mitral annulopapillary muscle continuity in patients with mitral stenosis

Importance of preservation of chordal apparatus in mitral valve replacement

Mitral valve replacement often involves disruption of the chordal apparatus with disturbance of the annulo-papillary continuity. This results in significant downgrading of ventricular function. Analyzes various reports to accurately assess the advantages of chordal preservation. This review briefly briefly reviews the surgical techniques. The advantages of chordal preservation are analyzed, with particular emphasis on the technical difficulties and potential complications involved.

Mitral valve replacement versus annuloplasty for treating severe functional mitral regurgitation

OBJECTIVES

To improve the clinical outcome of patients with severe functional mitral regurgitation (FMR) associated with ischemic cardiomyopathy (ICM), we compared the therapeutic efficacy of mitral annuloplasty (MAP) with that of mitral valve replacement (MVR).

METHODS

In a retrospective observation 63 consecutive patients underwent mitral valve surgery for severe ICM-FMR from November 1999 to March 2012. All patients had severe FMR (regurgitant volume >60 ml/beat) with Carpentier type I and type IIIb disease. Mean RV was 74.0 ± 35.0 ml/beat and coaptation depth was 12.7 ± 3.0 mm. Twenty-six patients (41.3 %) were treated by MVR with sparing of the subvalvular apparatus and 37 (58.7 %) by MAP.

RESULTS

Total in-hospital mortality was 6.3 %. Kaplan-Meier survival estimates at 1 and 5 years were 84.2 and 78.6 % in the MVR group and 82.6 and 71.6 % in the MAP group, with no significant difference between groups (p = 0.758). Freedom from major adverse cardiac and cerebrovascular events (MACCE) at 5 years was 66.9 % for patients treated by MVR and 64.1 % for those treated by MAP (p = 0.866). At the last follow-up visit, >grade II MR had recurred in 4 annuloplasty patients (10.8 %). In multivariate analysis, independent predictors of increased late death and MACCE were significantly associated with residual pulmonary hypertension (late death: odds ratio = 25.0, p = 0.0009; MACCE: odds ratio = 31.3, p = 0.0001).

CONCLUSIONS

Mitral valve replacement with sparing of the subvalvular apparatus is a safe and effective surgical alternative for patients with severe FMR.

Acute thrombosis of bioprosthetic mitral valve

We report a case of acute thrombosis of bioprosthetic mitral valve in a 59 year-old Korean female, who underwent a mitral valve replacement with a 25 mm Carpentier - Edwards PERIMOUNT Plus bioprosthesis (Edwards Lifesciences, Inc.; Irvine, CA, USA) and a mini-Maze procedure for correction of mitral stenosis (MS) and atrial fibrillation (AF). On the 10th postoperative day, the patient began to complain of increasing dyspnea and general malaise. Her symptoms worsened and developed into pulmonary edema. Echocardiography revealed a mean diastolic pressure gradient (MDPG) of 10 mmHg across the mitral valve and pressure-half time (PHT) of 166 msec. Due to progressive decompensated heart failure, the patient underwent a repeat sternotomy to replace the bioprosthetic mitral valve. Intraoperatively, we found a thrombosis around the bioprosthetic mitral valve. We excised the bioprosthetic mitral valve and replaced it with a 27 mm ATS mechanical valve (ATS medical, Inc.; Minneapolis, MN, USA). We experienced a rare case that required an early reoperation for a thrombosis of the bioprosthetic valve.

A remnant mitral subvalvular apparatus mimicking aortic valve vegetation after mitral valve replacement

Preservation of the subvalvular apparatus has the merits of postoperative outcomes during mitral valve replacement for mitral regurgitation. We performed mitral valve replacement with anterior and posterior leaflet chordal preservation in a 65-year-old woman. On the 2nd postoperative day, routine postoperative trans-thoracic echocardiography showed an unknown aortic subvalvular mobile mass. We report a case of a remnant mitral subvalvular apparatus detected by echocardiography after chordal preserving mitral valve replacement which was confused with postoperative aortic valve vegetation.

Early bioprosthetic valve failure caused by preserved native mitral valve leaflets

The importance of preservation of subvalvular apparatus and valve-ventricular continuity during mitral valve replacement (MVR) has been suggested for many years. The chordal-sparing MVR has been shown to be superior to the standard MVR with chordal resection in terms of improved left ventricular function and has been considered to be a safe procedure. However, we encounter a rare case requiring early reoperation for bioprosthetic valve failure caused by preserved leaflets after chordal-sparing MVR.

Partial resection of mitral leaflets during mitral valve replacement

Usually, after mitral leaflet tissue is resected, artificial chordae are used to obtain papillary muscle-to-mitral annulus continuity so as to preserve left ventricular performance. A modified technique that does not require resection of the posterior mitral leaflet and permits implantation of an adequate size of prosthesis is described.

Beginning and development of surgery for acquired valvular heart disease in Japan

The initiation and development of surgery for acquired valvular heart disease in Japan was reviewed. The first series of attempts at closed valvular surgery were performed in 1951-1952 by collaboration between the brothers Tohru and Shigeru Sakakibara in patients with pulmonary or mitral stenosis. During the popularization of closed valvular surgery, open heart surgery under direct vision was successfully performed by Shigeru Sakakibara with cooling of the body in 1954 and by using cardiopulmonary bypass (CPB) in 1956. With the development of CPB and artificial heart valves, closed valvular heart surgery was replaced by open surgery, which expanded rapidly during the 1960s and 1970s. Along with the serial introduction and improvement of mechanical vales thereafter, bioprosthetic valves were also introduced and were adopted for certain patients. Use of bioprosthetic valves in the aortic position exceeded 50% in 2005, along with the increase of elderly patients. Although trials of mitral valve plasty for mitral regurgitation were first done during the 1950s to 1960s in Japan, interest in valve plasty only increased during the late 1970s. Considering the patient's quality of life and the long-term results, mitral valve plasty became the major procedure (exceeding valve replacement) from 2004. In 2002, the Guideline for Surgical and Interventional Treatment of Valvular Heart Disease was published by a joint committee of the relevant academic societies, and it has made an important contribution to improving surgical outcomes.

Papillary Muscle Repositioning in Mitral Valve Replacement in Patients With Left Ventricular Dysfunction

BACKGROUND

The aim of this study was to investigate the feasibility of performing papillary muscle repositioning for mitral valve replacement procedures in patients with left ventricular dysfunction and to determine the early and late effects of this procedure on clinical outcome and left ventricular mechanics.

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.

Comparative Assessment of Chordal Preservation Versus Chordal Resection in Mitral Valve Replacement for Mitral Stenosis (Long-Term Follow-up: 8 Years)

Carrying out a mitral valve replacement (MVR) while preserving all chordae tendineae in patients with mitral regurgitation has been proven beneficial to the left ventricular performance. To evaluate the effectiveness of this technique in patients with mitral stenosis, a comparison of the echocardiographic data between patients who were operated on using this technique (Group Preservation = GroupP, n = 15), and those operated on using the conventional method of MVR (Group Conventional = GroupC, n = 15) was made. All patients were examined before surgery, 6 months after surgery and 8 years after surgery. The study population was limited to patients who had no evidence of coronary artery disease, aortic stenosis and/or regurgitation and patients who had pure mitral stenosis. Echocardiographic measurements obtained both 6 months and 8 years postoperatively revealed a significant decrease in the left ventricular ejection fraction in GroupC (61.33+/-9.29% preoperatively, 53.2+/-10.3% postoperatively). The difference between the decrease in the left ventricular ejection fraction of the two groups was statistically significant (-0.71+/-6.28% in GroupP, -8.07+/-13.35% in GroupC). There was no evidence of prosthetic valve dysfunction and no operative deaths. Two patients died in GroupP, 3 patients died in GroupC within the 8 year period. The conclusion was reached, that if suitable, mitral valve replacement while preserving the chordae tendineae is expected to have a beneficial effect on postoperative left ventricular performance in patients with mitral stenosis.

Chordal-sparing mitral valve replacement using artificial chordae tendineae for rheumatic mitral stenosis: experience of the "oblique" method

Chordal-sparing mitral valve replacement (CSMVR) has been proven to be beneficial for postoperative left ventricular (LV) function. In patients with mitral stenosis, however, diseased chordae tendineae (CT) often have to be replaced using artificial CT to achieve CSMVR. Previously, we reported that resusupension of artificial CT in an oblique direction enhances systolic LV function. Among 40 consecutive patients with mitral valve replacement (MVR), 17 (4 men and 13 women; mean age 66.5 years) with rheumatic mitral stenosis underwent CSMVR with oblique resuspension. Echocardiography was done before the operation, early (mean 25 days) after the operation, and at a late stage (mean 14 months). There was no mortality or major morbidity. LV ejection fraction late after the operation (68 +/- 8%) was better than that in the early period (61 +/- 8%, p < 0.01), and comparable to the preoperative level (65 +/- 9%). The oblique method may help to improve the results of MVR.

Early failure of bioprosthesis by preserved mitral leaflets

Complete preservation of the posterior mitral valve leaflet caused early thrombotic occlusion of two cusps of a Carpentier-Edward pericardial prosthesis implanted into the mitral position with subsequent bioprosthetic failure, necessitating reoperation.

Distance between mitral anulus and papillary muscles: anatomic study in normal human hearts

BACKGROUND

Preservation of the annulo-papillary muscle continuity in mitral valve replacement is important. Even in patients who require excision of the mitral apparatus, the continuity can be restored. However, there is no guide to the proper length for the resuspension.

METHODS

In 57 normal cadaveric hearts, the distance from the tip of the papillary muscle to its corresponding mitral anulus was directly measured.

RESULTS

The distance from the tip of the anterolateral papillary muscle to the left trigone (10-o'clock position: D10) and to the point between the anterior and the middle scallops of the mural leaflet (8-o'clock position: D8) was 23.5 +/- 3.7 mm and 23.2 +/- 3.6 mm, respectively. The distance from the tip of the posteromedial papillary muscle to the right trigone (2-o'clock position: D2) and to the point between the middle and the posterior scallops of the mural leaflet (4-o'clock position: D4) was 23.5 +/- 4.0 mm and 23.5 +/- 3.9 mm, respectively. There was no statistically significant difference among the 4 distances (P =.96). Each distance was significantly longer than the corresponding chordae tendineae (D10 vs the anterior main chorda: 17.2 +/- 3.9 mm, D8 vs the anterior cleft chorda: 14.5 +/- 3.2 mm, D2 vs the posterior main chorda: 17.9 +/- 4.3 mm, and D4 vs the posterior cleft chorda: 14.9 +/- 3.2 mm, respectively; P =.0001). The mean distance had a significant correlation with the mitral annular diameter (r = 0.31, P =.019).

CONCLUSIONS

In normal hearts, the annulo-papillary muscle distances of the mitral apparatus are similar in 2-, 4-, 8-, and 10-o'clock positions and correlate with the mitral annular diameter.

Exploring better methods to preserve the chordae tendineae during mitral valve replacement

BACKGROUND

It is not known how best to resuspend the mitral chordae tendineae during mitral valve replacement to optimize postoperative left ventricular (LV) systolic and diastolic function.

METHODS

Six different techniques to preserve the chordae during mitral valve replacement were compared in 12 dogs using a nondistorting isovolumic technique: conventional, all chordae severed; anterior, all chordae preserved anteriorly; partial, anterior papillary muscle chordae preserved anteriorly; posterior, all chordae preserved posteriorly; oblique, anterior papillary muscle chordae directed anteriorly and posterior papillary muscle chordae posteriorly; and counter, opposite of oblique chordal direction. Control measurements (no chordal tension) were recorded between each experimental condition.

RESULTS

The oblique method tended to have the best LV systolic function versus the conventional method (Emax = 4.0 +/- 1.8 versus 3.3 +/- 1.2 mm Hg/mL [mean +/- standard deviation]; p = 0.08 by repeated-measures analysis of variance; physiologic intercept Ees100 = 20.3 +/- 8.6 mL [p < 0.05 versus control]), with no major change in LV diastolic stiffness. The posterior method had a lower Emax (3.3 +/- 1.2 mm Hg/mL) than the oblique method, but a similar Ees100 (20.8 +/-8.1 mL; p < 0.05 versus control) and the best diastolic LV performance (LV diastolic stiffness = 0.46 +/- 0.23 mm Hg/mL). The counter method also had good systolic function (Emax = 3.8 +/- 1.2 mm Hg/mL; Ees100 = 19.7 +/- 7.5 mL; p < 0.05 versus control), but had less favorable diastolic properties (0.65 +/- 0.37 mm Hg/mL; p < 0.05 by repeated-measures analysis of variance versus posterior).

CONCLUSIONS

In this isovolumic preparation in normal canine hearts, the oblique method of chordal resuspension was associated with the best LV systolic function, whereas the counter technique impaired LV diastolic function. These preliminary results warrant further study in ejecting and failing hearts to determine conclusively which chordal orientation best preserves LV performance after mitral valve replacement.