Entire Mitral Valve Reconstruction Using Porcine Extracellular Matrix: Adding a Ring Annuloplasty.

PURPOSE: This study investigated the implications of inserting a flexible annuloplasty ring after reconstructing the entire mitral valve in a porcine model using a previously investigated tube graft design made of 2-ply small intestinal submucosa extracellular matrix (CorMatrix®). METHODS: An acute model with eight 80-kg pigs, each acting as its own control, was used. The entire mitral valve was reconstructed with a 2-ply small intestinal submucosa extracellular matrix tube graft (CorMatrix®). Subsequently, a Simulus® flexible ring was inserted. The characterization was based on mitral annular geometry and valvular dynamics with sonomicrometry and echocardiography. RESULTS: After adding the ring annuloplasty, the in-plane annular dynamics were more constant throughout the cardiac cycle compared to the reconstruction alone. However, the commissure-commissure distance was statistically significantly decreased [35.0 ± 3.4 mm vs. 27.4 ± 1.9 mm, P < 0.001, diff = - 7.6 mm, 95% CI, - 9.8 to (-5.4) mm] after ring insertion, changing the physiological annular D-shape into a circular shape which created folds at the coaptation zone resulting in a central regurgitant jet on color Doppler. CONCLUSION: We successfully reconstructed the entire mitral valve using 2-ply small intestinal submucosal extracellular matrix (CorMatrix®) combined with a flexible annuloplasty. The annuloplasty reduced the unphysiological systolic widening previously found with this reconstructive technique. However, the Simulus flex ring changed the physiological annular D-shape into a circular shape and hindered a correct unfolding of the leaflets. Thus, we do not recommend a flexible ring in conjunction with this reconstructive technique; further investigations are needed to discover a more suitable remodelling annuloplasty.

Comparison of aortic valve repair techniques with single- and double-ring annuloplasties.

OBJECTIVES: For patients with isolated aortic regurgitation, a double sub- and supravalvular annuloplasty has been shown to reduce recurrent aortic regurgitation after aortic valve repair compared with a single subvalvular annuloplasty. The objective of this study was to compare the geometrical and dynamic properties of single- and double-ring annuloplasties in an in vitro model. METHODS: Eighteen aortic roots from 80 kg pigs were randomized into a control, single-ring and double-ring group. Experiments were conducted in a pulsatile in vitro model. Hydrodynamics, radial force measurements at annular and sinotubular level and 2D echographic imaging were obtained. RESULTS: Both the single- and double-ring annuloplasties downsized the aortic annulus and sinotubular junction (STJ) significantly and increased the coaptation height. The double-ring annuloplasty showed an additional significant increase in coaptation height compared with the single ring [8.5 (0.9)-9.8 (0.8) mm, P < 0.01]. The single-ring annuloplasty reduced radial forces at both levels, whereas the double-ring annuloplasty showed the greatest force reduction of the STJ. CONCLUSIONS: By treating the whole functional aortic annulus, encompassing both the aortic annulus and the STJ, a greater force reduction is observed. A subvalvular annuloplasty alone is efficient in reducing aortic annulus diameter and increasing coaptation height, however, by treating the STJ as well, an additional effect is observed on coaptation height, creating a more efficient stabilization. Reduction of annular force-distensibility ratio with the double-ring annuloplasty compared with the native controls indicates a sustained stabilizing effect.

[Treatment of traumatic injuries of the peripheral facial nerve].

This review summarises the current knowledge of treatment strategies in traumatic extracranial facial nerve injuries. Facial nerve injuries cause significant psychologic and functional morbidity. We present a guideline for the clinical management including physical examination and surgical treatment. To regain mimetic function after facial nerve injuries it is crucial to ensure that microsurgical reconstruction is completed preferably within 24 hours, and no later than 72 hours from the time of accident.

[Microsurgical reconstruction after traumatic lesion of the peripheral facial nerve].

In this case report, a 17-year-old female underwent microsurgical exploration and neurorrhaphy after a glass pane accident resulting in traumatic lesion of the right temporal facial nerve branch. Nine months after reconstruction she had regained function of the frontalis muscle. When patients with traumatic facial nerve injuries are admitted to hospital, it is crucial to consult with a microsurgical center to ensure that reconstruction is completed within 24-72 hours from the time of accident to regain mimetic function.

Annular and subvalvular dynamics after extracellular matrix mitral tube graft implantation in pigs.

OBJECTIVES: Entire mitral valve reconstruction with an extracellular matrix tube graft is a potential candidate to overcome the current limitations of mechanical and bioprosthetic valves. However, clinical data have raised concern with respect to patch failure. The aim of our study was to evaluate the impact of extracellular matrix mitral tube graft implantation on mitral annular and subvalvular regional dynamics in pigs. METHODS: A modified tube graft design made of 2-ply extracellular matrix was used (CorMatrix®; Cardiovascular Inc., Alpharetta, GA, USA). The reconstructions were performed in an acute 80-kg porcine model (N = 8), where each pig acted as its own control. Haemodynamics were assessed with Mikro-Tip pressure catheters and mitral annular and subvalvular geometry and dynamics with sonomicrometry. RESULTS: Catheter-based peak left atrial pressure and pressure difference across the mitral and aortic valves in the reconstructions were comparable to the values seen in the native mitral valves. Also comparable were maximum mitral annular area (755 ± 100 mm2), maximum septal-lateral distance (29.7 ± 1.7 mm), maximum commissure-commissure distance (35.0 ± 3.4 mm), end-systolic annular height-to-commissural width ratio (10.2 ± 1.0%) and end-diastolic interpapillary muscle distance (27.7 ± 3.3 mm). Systolic expansion of the mitral annulus was, however, observed after reconstruction. CONCLUSIONS: The reconstructed mitral valves were fully functional without regurgitation, obstruction or stenosis. The reconstructed mitral annular and subvalvular geometry and subvalvular dynamics were found in the same range to those in the native mitral valve. A regional annular ballooning effect occurred that might predispose to patch failure. However, the greatest risk was found at the papillary muscle attachments.

Annular Dynamics and Leaflet Geometry in Patch Reconstruction of the Posterior Mitral Leaflet After Adding a Flexible Annuloplasty Ring.

PURPOSE: Patch reconstruction of the posterior mitral leaflet using small intestinal submucosa extracellular matrix has been successfully performed in a porcine study. The patch reconstruction, however, resulted in non-physiological systolic widening of the mitral annulus, suggesting the need for an annuloplasty ring. The objective was to characterize the impact on annular dynamics and leaflet geometry of adding a flexible annuloplasty ring to the posterior mitral leaflet patch reconstruction. METHODS: Measurements were performed in an acute 80-kg porcine model, with seven pigs acting as their own controls. The posterior mitral leaflet was reconstructed with a 2-ply small intestinal submucosa extracellular matrix patch (CorMatrix®). Additionally, a Simulus® Flexible Annuloplasty Ring (Medtronic Inc., Minneapolis, MN, USA) was inserted. Mitral annular dynamics were evaluated using sonomicrometry, and leaflet geometry was described using echocardiography. RESULTS: The annuloplasty ring reduced mitral annular dimensions and restricted cyclic changes in mitral annular area (126 ± 19 vs. 30 ± 13 mm2, p < 0.001), septal-lateral and commisure-commisure distances. Ring annuloplasty prevented systolic widening in the mitral annulus after posterior mitral leaflet reconstruction. The annular saddle shape and leaflet coaptation length (8.7 ± 2.3 vs. 9.7 ± 1.3 mm, p = 0.221) were comparable before and after ring insertion. CONCLUSIONS: The flexible annuloplasty ring resulted in a downsized annulus with restriction of cyclic annular changes in the reconstructed mitral valve. Ring insertion preserved the annular saddle shape and coaptation length. The ring annuloplasty counteracted the non-physiological annular dynamics, and this may improve durability of the posterior mitral leaflet patch reconstruction.

Altered stresses and dynamics after single and double annuloplasty ring for aortic valve repair.

OBJECTIVES: Aortic valve repair procedures for the treatment of isolated aortic valve insufficiency may be improved by stabilizing the functional aortic annulus using a double annuloplasty ring at the aortic annulus and sinotubular junction (STJ). The objective of this study was to compare the geometrical changes and aortic root stress distribution when using a single subvalvular ring and a double sub- and supravalvular ring in vivo. METHODS: Both the single- and double-ring procedures were performed successively in nine 80-kg pigs. Measurements were performed intraoperatively using sonomicrometry crystals in the aortic root to evaluate geometrical changes and annular and STJ force transducers measuring the segmental radial stress distribution. RESULTS: The total force in the STJ was significantly reduced after the double-ring procedure from 1.7 ± 0.6 to 0.04 ± 1.1 N (P = 0.001). The double-ring procedure significantly reduced the STJ area from 234.8 ± 37.6 to 147.5 ± 31.8 mm2 (P = 0.001) and expansibility from 17 ± 6% to 8 ± 3% (P = 0.001). With the single-ring procedure, the STJ shape was circular but became more oval with the double-ring procedure. The double-ring procedure did not affect stress distribution or geometry in the aortic annulus. CONCLUSIONS: The double-ring procedure stabilized the whole aortic root by reducing radial stress distribution in the STJ more efficiently than the single-ring procedure. Both area and expansibility were reduced with the double-ring procedure. These results confirm the importance of addressing the entire functional aortic annulus for optimal aortic valve repair procedures.

Entire mitral reconstruction with porcine extracellular matrix in an acute porcine model.

OBJECTIVE: The objective of our study was to investigate the feasibility of reconstructing the entire mitral valvular and subvalvular apparatus in pigs using a modified tube graft design made of 2-ply small intestinal submucosa extracellular matrix. METHODS: The reconstructions were performed in an acute 80-kg porcine model with 8 pigs, each acting as its own control. A modified tube graft was designed from a sheet of 2-ply small intestinal submucosa extracellular matrix. Before and after mitral valve reconstruction, echocardiography was used to assess mitral regurgitation, left ventricular outflow tract obstruction due to systolic anterior motion, mitral stenosis, leaflet mobility, and leaflet geometry. RESULTS: The reconstructed mitral valves were fully functional without any observable echocardiographic signs of regurgitation. We did not observe any left ventricular outflow tract obstruction due to systolic anterior motion nor any mitral valve stenosis, despite a diminished septal-lateral distance after reconstruction. The reconstruction had a reduced tenting area, a reduced coaptation length (9.6 ± 1.7 mm vs 7.9 ± 1.0 mm, P = .010, diff = -1.7 mm, 95% confidence interval, -3.1 to -0.4 mm), and atrial bending of both leaflets. CONCLUSIONS: In this acute porcine study, entire mitral valvular and subvalvular apparatus reconstruction using a modified tube graft design made from 2-ply small intestinal submucosal extracellular matrix was feasible. The 2-ply small intestinal submucosa extracellular matrix could withstand the pressure exerted by the left ventricle without any signs of tearing or rupture. These promising results warrant further assessment of both the annular geometry and the long-term durability.

Comparison of Dacron ring and suture annuloplasty for aortic valve repair-a porcine study.

BACKGROUND: A subvalvular annuloplasty is often used for aortic valve repair in patients with isolated aortic regurgitation with aortic annulus dilatation. Our aim was to characterize and compare annulus geometry and dynamics of the Dacron ring and suture annuloplasty and compare it with the native aortic annulus under standardized conditions. METHODS: We randomized 29 pigs of 80 kg into a Dacron ring group, a suture annuloplasty group and a native control group. The assessment was performed using sonomicrometry crystals for evaluation of dynamic geometry, and pressure measurements and echocardiography to evaluate valve performance. RESULTS: Aortic annulus area (AAA) was significantly reduced in the Dacron and Suture group compared with the Native group. Expansibility was similar and within normal physiologic limits in all three groups (Native: 12%±7%; Dacron: 11%±3%; Suture: 10%±4%). The largest segmental expansion was observed at the right coronary sinus (RC) in the Native and Dacron group but in the Suture group there was no significant difference between segments. The aortic annulus was primarily oval in systole and became more circular in diastole in the Native and Dacron group, however, in the Suture group, the sphericity remained relatively unchanged throughout the cardiac cycle. CONCLUSIONS: This study is the first to describe and compare detailed segmental geometry of the Dacron ring and suture annuloplasty in a standardized porcine model. The two annuloplasties effectively downsized the aortic annulus, while expansibility was maintained. Each annuloplasty had its own geometrical characteristics, but the Dacron ring was more similar to the native aortic annulus than the suture annuloplasty. This study suggests that the Dacron ring offers a more physiological and standardized support by mimicking the geometry and dynamics of the native aortic annulus and thus is a preferable choice over the suture annuloplasty for valve-sparing aortic root procedures.

Comparison of the Dacron ring and suture annuloplasty for aortic root repair: an in vitro evaluation.

OBJECTIVES: Increasing evidence shows that annular stabilization is essential in most aortic valve repair procedures. However, a standardized comparison of the 2 commonly used annuloplasty procedures is lacking. We hypothesized that the Dacron ring is more rigid than the polytetrafluoroethylene suture, whereas both procedures decrease annular dimensions. The aim of this study was to compare the biomechanical properties of the ring and suture techniques with native aortic roots in vitro. METHODS: Eighteen aortic roots explanted from 80-kg pigs were randomized into a Dacron ring group, a suture annuloplasty group and a native control group. Each sample was tested in a pulsatile in vitro model with a force transducer attached to the aortic annulus to obtain radial force measurements, and annular dynamics was evaluated using 2-dimensional echography. RESULTS: Among the 2 annuloplasty procedures, only the Dacron ring group provided a significant reduction in the annular diameter compared with the native group (P < 0.006). Both annuloplasty procedures significantly reduced the geometric orifice area, tenting area and sinus diameter while increasing the coaptation length compared with the native group. Systolic annular distension was retained between groups, although the total radial forces were significantly reduced in the procedure groups compared with the native group (ring 1.07 ± 0.45 N, suture 1.13 ± 0.39 N and native 3.55 ± 1.34 N, P < 0.001). CONCLUSIONS: Although both annuloplasty procedures increase coaptation length and decrease geometric orifice area, a significant downsizing of the annulus was achieved using the Dacron ring only. The systolic annular distension was similar to the native aortic root, whereas the radial annular forces were evenly decreased by both annuloplasty procedures. Long-term studies are needed to disclose any difference in long-term effect of the annuloplasty procedures.

Mitral valve posterior leaflet reconstruction using extracellular matrix: an acute porcine study.

OBJECTIVES: To investigate mitral valve posterior leaflet and subvalvular reconstruction using a 2-ply small intestinal submucosal extracellular matrix sheet. METHODS: Mitral valve posterior leaflet and subvalvular reconstruction was characterized in an acute 80-kg porcine model with 7 pigs acting as their own controls. The characterization was based on pressure catheter measurements of pressure differences to identify mitral regurgitation, stenosis and systolic anterior motion. Furthermore, echocardiography was used for the evaluation of leaflet mobility and geometry, whereas sonomicrometry was used to describe annular and subvalvular geometry. RESULTS: The reconstructed mitral valve was fully functional without any signs of regurgitation (peak left atrial pressure for baseline and reconstruction 12 ± 2 mmHg vs 11 ± 2 mmHg, P = 0.550), mitral valve stenosis (mean pressure difference across the mitral valve 4.8 ± 2.3 mmHg vs 4.1 ± 2.3 mmHg, P = 0.589) or systolic anterior motion. The echocardiographic characterization revealed septal-lateral downsizing, reduced tenting area, increased coaptation length (6.0 ± 0.6 mm vs 8.7 ± 2.3 mm, P = 0.002) and an atrial bend of the reconstructed posterior leaflet. A ballooning effect of the patch material was present at the posterior annular segment. CONCLUSIONS: Mitral valve posterior leaflet and subvalvular reconstruction using a 2-ply small intestinal submucosal extracellular matrix sheet as patch material was possible in an acute porcine model. The reconstructed mitral valve was fully functional without signs of mitral valve stenosis, valve regurgitation, stenosis or systolic anterior motion. The ballooning appearance of the patch material might, however, constitute an altered leaflet stress distribution in this area.