Replacement of chordae tendineae using expanded polytetrafluoroethylene (ePTFE) sutures during mitral valve replacement in patients with severe 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.

Modified loop technique in three dogs with mitral regurgitation

Mitral valvuloplasty (MVP) is used in dogs with refractory mitral regurgitation (MR); however, it is difficult to tie the artificial chord, i.e., the expanded polytetrafluoroethylene suture, at the planned height of the mitral valve, because of the slippery nature of the knot. The loop technique has resolved these difficulties in humans. Premanufactured loops (length, 8.0-15.0 mm with 1.0-mm increments) were used in the new modified loop technique. In the current study, cardiac murmurs disappeared, and the MR markedly improved or completely disappeared approximately 3 months after surgery in 3 dogs. Therefore, this new technique might be effective in dogs.

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.

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.

Importance of subvalvular preservation and early operation in mitral valve surgery

BACKGROUND

Mitral valve replacement (MVR) has a high mortality and morbidity. It has been suggested that preservation of the subvalvular apparatus and more optimal timing of surgery might improve outcome.

METHODS AND RESULTS

We performed a retrospective study of 612 consecutive patients who underwent mitral valve repair or replacement: 226 patients had repair, 68 had replacement with subvalvular preservation (MVR/SVP), and 318 had replacement without subvalvular preservation (MVR/NoSVP). Baseline characteristics were most unfavorable in the repair group with respect to age (P = .002) and in the repair and MVR/SVP groups with respect to NYHA functional class and left ventricular function (P = .044). Thirty-day mortality was lower in the repair (1.8%, P = .046) and MVR/SVP (1.5%. P = NS) groups than the MVR/NoSVP group (5.0%). Overall survival at 7 years was better in the repair (71.2 +/- 5.6%. P = .022) and MVR/SVP (66.2 +/- 12.4%, P = .017) groups than the MVR/NoSVP group (63.5 +/- 3.4%). Myocardial failure caused 66 of 107 complication-related deaths. Multivariate analysis confirmed independent beneficial effects of repair on 30-day mortality (odds ratio, 0.27, P < .05) and of repair and MVR/SVP on overall mortality (hazard ratios, 0.43, P < .001 and 0.40, P < .05, respectively) and complication-related death hazard ratios, 0.38, P < .001 and 0.35, P < .05, respectively). Preoperative NYHA class III or IV symptoms and left ventricular impairment were independent risk factors for death and myocardial failure.

CONCLUSIONS

Mitral valve repair is superior to replacement. If repair is not feasible, the subvalvular apparatus should be preserved. Early surgery before the development of severe symptoms and demonstrable left ventricular impairment is also needed to optimize outcome.

Pathologic aspects of polytetrafluoroethylene sutures in human heart

BACKGROUND

Polytetrafluoroethylene (PTFE) sutures have been widely used as a mitral chord substitute. We present the cases of 4 patients who underwent mitral valve repair with chordal replacement by PTFE sutures and these required another operation. This gave us the chance to examine the PTFE sutures.

METHODS

Structural analysis of the PTFE sutures was performed 26 to 378 days postoperatively. The specimens were examined grossly, microscopically, and by scanning or transmission electron microscopy or both.

RESULTS

The PTFE suture in 1 patient was found to be completely covered with endothelial cells 154 days postoperatively. There was no calcification, and the flexibility and pliability of the PTFE sutures was preserved. Even though the PTFE sutures seemed uncovered on visual inspection, there was a thin lining of collagen and fibrin on the surface. Endothelial cells were seen in areas that looked clear in one specimen 26 days postoperatively.

CONCLUSIONS

We think that the new layer of collagen could be promising in terms of durability and that the endothelial layer wil resemble normal tissue in its anticoagulant properties.