Performance and healing of an expanded polytetrafluoroethylene multichordal device at 6 months after repair of mitral leaflet flail in swine.

OBJECTIVE: Repairing a prolapsed mitral valve that involves multiple cusps is procedurally complicated and carries a higher risk of failure when performed with individual neochordae. Inserting multiple neochordae into the papillary muscle, sizing, and aligning them in a manner that can restore coaptation is challenging. A multichordal mitral valve apparatus (MitraPatch) with a single neopapillary muscle section, 4 neochordae with each chord ending in a neoleaflet section, was developed. In this study, the 6-month outcomes of using this apparatus to repair mitral prolapse in swine is reported. METHODS: Seven pigs (n = 7) with prolapse from mitral chordal transection were repaired with the device. One pig was used to develop the procedure, and 6 swine received the implant and were survived to 150 days (n = 4) and 180 days (n = 2), with monthly echocardiographic examinations. All hearts were explanted for gross necropsy and detailed histopathology. RESULTS: Severe mitral regurgitation (MR) was observed after chordal transection in all pigs. Repairing the valve with the device reduced MR to none-or-trace levels in 3 swine, grade 1 in 3 swine, and 1 to 2+ in 1 swine immediately after surgery. In the pigs with none/trace/grade 1 MR, the device was intact and coaptation was fully restored as observed on serial echocardiograms. The device was intact, without dehiscence, stretching, or fibrosis at termination. The neoleaflet and neopapillary sections of the device elicited a host response, which is on track to produce living valve replacement tissue, but we cannot tell how controlled this might be several years later. In the pig with grade 1 to 2+ MR, accidental transection of both marginal and strut chordae in that region was observed at death, with dehiscence of the device at the site of its insertion into the leaflet. CONCLUSIONS: The anatomic principles that guide this multichordal design appear to be valid, with good hemodynamic performance and a controlled host response at 6 months.

Use of a New Expanded Polytetrafluoroethylene Multichordal Mitral Apparatus (MitraPatch) to Repair Complex Mitral Valve Lesions.

OBJECTIVE: We report a new expanded polytetrafluoroethylene multichordal mitral apparatus (MitraPatch) to simplify mitral repairs involving multiple cusps and sought to describe the surgical technique and demonstrate the efficacy of the device. METHODS: MitraPatch was laser cut from a single sheet of expanded polytetrafluoroethylene and mounted on a custom-designed handle. Surgical technique to deploy the apparatus on the native mitral valve was developed in ex vivo porcine hearts. Hemodynamic efficacy of repairing mitral prolapse and regurgitation was assessed in ex vivo hearts and in five 30-day chronic swine, with histopathology in an additional swine at 120 days after implantation. RESULTS: In ex vivo heart studies, leaflet coaptation was restored from 0 mm at the posterior prolapsing segment to 8.1 ± 2.2 mm after repair with the MitraPatch (P < 0.05) and to 10.2 ± 1.3 mm after the repair of the anterior leaflet (P < 0.05). In in vivo studies, valve function at 30 days was considered good, with none to trace regurgitation. Device was flexible, without tissue overgrowth or dehiscence. At 120 days, complete endothelialization was observed. CONCLUSIONS: The multichordal MitraPatch can potentially simplify complex mitral valve repairs involving multiple leaflet cusps, possibly enabling an optimal mitral repair even by surgeons without the focused high-volume experience.

Pre-clinical Experience with a Multi-Chordal Patch for Mitral Valve Repair.

Surgical repair of flail mitral valve leaflets with neochordoplasty has good outcomes, but implementing it in anterior and bi-leaflet leaflet repair is challenging. Placing and sizing individual neochordae is time consuming and error prone, with persistent localized flail if performed incorrectly. In this study, we report our pre-clinical experience with a novel multi-chordal patch for mitral valve repair. The device was designed based on human cadaver hearts, and laser cut from expanded polytetrafluoroethylene. The prototypes were tested in: (stage 1) ex vivo hearts with leaflet flail (N = 6), (stage 2) acute swine induced with flail (N = 6), and (stage 3) two chronic swine survived to 23 and 120 days (N = 2). A2 and P2 prolapse were successfully repaired with coaptation length restored to 8.1 ± 2.2mm after posterior repair and to 10.2 ± 1.3mm after anterior repair in ex vivo hearts. In vivo, trace regurgitation was seen after repair with excellent patch durability, healing, and endothelialization at euthanasia. A new device for easier mitral repair is reported, with good early pre-clinical outcomes.

Mitral valve repair with artificial chordae: a review of its history, technical details, long-term results, and pathology.

Mitral valve repair is considered the procedure of choice for correcting mitral regurgitation in myxomatous disease, providing long-term results that are superior to those with valve replacement. The use of artificial chordae to replace elongated or ruptured chordae responsible for mitral valve prolapse and severe mitral regurgitation has been the subject of extensive experimental work to define feasibility, reproducibility, and effectiveness of this procedure. Artificial chordae made of autologous or xenograft pericardium have been replaced by chordae made of expanded polytetrafluoroethylene (PTFE), a material with the unique property of becoming covered by host fibrosa and endothelium. The use of artificial chordae made of PTFE has been validated clinically over the past 2 decades and has been an increasing component of the surgical armamentarium for mitral valve repair. This article reviews the history, details of the relevant surgical techniques, long-term results, and fate of artificial chordae in mitral reconstructive surgery.

The effects on cordal and leaflet stiffness of severe apical, posterior, and outward papillary displacement in advanced ventricular mechanism heart failure and mitral insufficiency.

BACKGROUND AND AIM OF THE STUDY: During the normal opening and closing of the mitral valve there is a finely tuned interaction between the changing ventricular dimensions and fluid pressures, the movement of papillary muscles apically, posteriorly and apart during diastole and in the opposite direction during systole, interactions between leaflets and their controlling cords, and the fluid dynamic forces being exerted on them. The main rough zone cords and the smooth zone of the anterior leaflet are under maximum tension in systole, but retain some tension throughout the cycle. The free edge cords and the rough zone of the leaflets can have no or minimal tension during diastole, and much less tension than the main rough zone cords and the smooth zone in systole. The variability of the form and distribution of rough zone cords influences the flexibility of the rough zone. The net effect of this interaction is a valve that opens rapidly for unobstructed forward flow, and closes at the end of the cycle with minimal leakage. The apical displacement of, usually, the right inferior papillary muscle as a result of ischemic ventricular disease pulls the leaflets into separation because the origins of cords supporting the anterior and posterior leaflets arise specifically from the anterior and posterior sides of each papillary muscle. Myocardial ischemia producing apical papillary displacement can be associated with heart failure and mitral insufficiency. Annuloplasty reducing the annulus to less than the normal systolic dimension can be effective in eliminating both insufficiency and heart failure when the papillary displacement is dominantly apical. In more severe cases of heart failure and mitral insufficiency, the mid-ventricular dimensions increase to a more severe degree, and both papillary muscles are displaced outwards and posteriorly. METHODS AND RESULTS: Static in vitro experiments performed on three human and nine pig hearts showed that the outward papillary displacements increased the tension on first-order cords, rendering the anterior leaflet and the central scallop of the posterior leaflet stiff. The addition of posterior displacement caused the anterior leaflet to become directed at an angle to the displaced papillary muscles, and the scallops of the posterior leaflet to be perpendicularly splayed around the posterior left ventricular wall, such that the valve no longer opened or closed correctly. CONCLUSION: The valve no longer opens or closes properly, and annuloplasty is no longer of use in restoring valve function.

Quattro valve trial at mid-term: December 1996 to November 2004.

BACKGROUND AND AIM OF THE STUDY: The Quattro valve is a stentless pericardial mitral bioprosthesis that is treated with a post-tanning aldehyde capping designed to reduce calcification. A prospective trial was started in December 1996; herein are reported the results of the three centers that performed the surgery and followed up patients in the majority of cases. Young patients were deliberately included in the trial. METHODS: Follow up data from 175 patients (mean age 46 years; range: 12-87 years) were collected and analyzed. Among patients, 44% were aged < 40 years. Follow up was 91% complete; mean follow up was 3.4 years (range: 0-7.5 years); total follow up was 465 patient-years (pt-yr). Clinical outcome was assessed according to the AATS/STS guidelines, and results analyzed according to Kaplan-Meier product limit calculation and by FDA Optimal Performance Criteria (OPC). RESULTS: Early mortality was 1.7% (all non-valve related). At 60 months after surgery, mean overall survival was 84.8 +/- 3.6%, mean overall freedom from valve-related death was 99.2 +/- 0.9%, and mean overall freedom from calcification, pannus and tears was 96.1 +/- 2.2%. FDA OPC values (data for mechanical valve, tissue valve, Quattro valve in patients aged < 40 years and of all ages, respectively; expressed as %/pt-yr) were as follows: thromboembolism/stroke 3.0, 2.5, 0, 0.4; thrombosis 0.8, 0.2, 0, 0; major hemorrhage 1.5, 0.9, 0, 0.4; major perivalvular leak 0.6, 0.6, 0.4, 0.6; late endocarditis 1.2, 1.2, 1.8, 1.3; calcification/pannus 0, 0, 0.8, 0.6. Statistical analysis of these data showed there to be no difference between patients aged less or more than 40 years. CONCLUSION: Overall mid-term results with the Quattro valve were acceptable. The lack of early calcification in young patients shows promise. More young patient-years of follow up will be needed to establish a secure indication for use in young, rheumatic patients where anticoagulation control is deficient.