Transapical mitral valved stent implantation: A survival series in swine (original) (raw)

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Transapical Mitral Valved Stent Implantation

The Annals of Thoracic Surgery, 2008

Background. Transcatheter aortic and pulmonary valve replacement is currently being tested in human trials. Efforts to create a valved stent to replace the atrioventricular valves have shown limited success. This is due to their their complex anatomy and function.

Mitral valved stent implantation

European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery, 2010

To date, transfemoral and trans-apical valved stent implantation techniques are limited to the replacement of pulmonary and aortic valves in a strictly selected group of patients. The current study was designed to assess the short-term follow-up using a mitral valved stent in off-pump technique. A self-expanding, repositionable mitral valved stent was created for trans-apical implantation. Five pigs underwent successful trans-catheter implantation. Data were gathered to assess the animals' haemodynamical stability after stent implantation (n=5), 6h (n=5) and 1 week (n=4). The valved stent function was assessed by trans-oesophageal echocardiography and ventriculogram. Cardiac computed tomography (CT) was used to evaluate positioning of the new implant. Precise valved stent deployment and accurate subsequent adjustment of its intra-annular position allowed for reduction of paravalvular leakage in all animals. The deployment time ranged from 122 to 271 s and blood loss from 65 to 2...

Off-pump transapical mitral valve replacement. Discussion

European Journal of Cardio Thoracic Surgery, 2009

Objective: Percutaneous valve replacement was recently introduced, and reports of early clinical experience have already been published. To date, this technique is limited to the replacement of pulmonary and aortic valves in a strictly selected group of patients. The aim of this study was to analyse a self-expanding valved stent for minimally invasive replacement of the mitral valve in animals. Methods: A newly designed nitinol stent was specially designed for this experimental acute study. It comprised of a left ventricular tubular stent with star shaped left atrial anchoring springs and carried a trileaflet bovine pericardial valve. A polytetrafluoroethylene membrane was sutured to envelop the atrial springs and the outside of the ventricular stent. The ventricular anchoring system was the same as in our previously reported results with a similar mitral valved stent. Seven pigs underwent minimally invasive off-pump mitral valved stent implantation. This was performed through a lower ministernotomy and a standard transapical approach under transoesophageal echocardiographic (TEE) guidance was used. Results: The valved stent is fully retrievable and precise deployment and accurate adjustment of its intra-annular position is achievable to eliminate paravalvular leakage. The deployment time ranged from 127 to 255 s and the blood loss from 70 to 220 cc. One animal died of intractable ventricular fibrillation. Mitral regurgitation in all surviving animals was minimal (trace in 5/6 and mild in 1/6 during echo examination; on the contrast ventriculogram no mitral insufficiency was observed except in one documented as mild paravalvular regurgitation). These animals remained haemodynamically stable (6/ 6) and without TEE or ventriculographic changes for 1 h. Conclusion: Implantation of a tricuspid bovine pericardial valved stent in the mitral position is feasible in pigs through a transcatheter approach. This was possible through a smaller delivery system than previously reported. Additional studies are required to demonstrate long-term feasibility, durability, and heart function. #

Double-crowned valved stents for off-pump mitral valve replacement. Commentary and Discussion

European Journal of Cardio Thoracic Surgery, 2005

Objective: An animal model has been designed to assess the feasibility of off-pump mitral valve replacement using valved stents. Methods: Glutaraldehyde-preserved homograft was sutured inside a prosthetic tube (Dacron). Then, two self-expandable nitinol Z-stents were sutured on the external surface of the prosthesis in such a way to create two self-expanding crowns for fixation. In adult pigs and under general anesthesia, the left atrium was exposed through a left thoracotomy and atrio-ventricular roadmapping was performed with intravascular ultrasound (IVUS) and fluoroscopy. The double-crowned valved stents were loaded into a delivery sheath. The sheath was then introduced into the left atrium and the valved stents was deployed in mitral position in such a way that the part in between the two stents was at the level of the mitral annulus. Intracardiac Unltrasound (ICUS) was used to assess the valve function. Hemodynamic parameters were gathered as well. Animal survived for no more than 3 h after the valve deployment and gross anatomy examination of the left heart was carried out. Results: The mean height of the valved stents was 29.4G0.2 mm, with an internal diameter of 20.4G1.0 mm, and an external diameter of 25.5G0.8 mm. The procedure was successfully carried out in eight animals. In vivo evaluation showed a native mitral annulus diameter of 24.9G0.6 mm, and a mean mitral valve area of 421.4G17.5 mm 2 . ICUS showed a mild mitral regurgitation in three out of eight animals. Mean pressure gradient across the valved stents was 2.6G3.1 mmHg. Mean pressure gradient across the left ventricular outflow tract (LVOT) was 6.6G5.2 mmHg. The mean survival time was 97.5G56.3 min (survival time range was 40-180 min). One animal died due to the occlusion of the LVOT because of valved stents displacement. Postmortem evaluation confirmed correct positioning of the valved stent in the mitral position in seven out of eight animals. No atrial or ventricular lesions due to the valved stents were found. Conclusions: Off-pump implantation of a self-expandable valved stent in the mitral position is technically feasible. Further studies will assess if this procedure is also feasible in humans.

Double-crowned valved stents for off-pump mitral valve replacement☆

European Journal of Cardio-Thoracic Surgery, 2005

Objective: An animal model has been designed to assess the feasibility of off-pump mitral valve replacement using valved stents. Methods: Glutaraldehyde-preserved homograft was sutured inside a prosthetic tube (Dacron). Then, two self-expandable nitinol Z-stents were sutured on the external surface of the prosthesis in such a way to create two self-expanding crowns for fixation. In adult pigs and under general anesthesia, the left atrium was exposed through a left thoracotomy and atrio-ventricular roadmapping was performed with intravascular ultrasound (IVUS) and fluoroscopy. The double-crowned valved stents were loaded into a delivery sheath. The sheath was then introduced into the left atrium and the valved stents was deployed in mitral position in such a way that the part in between the two stents was at the level of the mitral annulus. Intracardiac Unltrasound (ICUS) was used to assess the valve function. Hemodynamic parameters were gathered as well. Animal survived for no more than 3 h after the valve deployment and gross anatomy examination of the left heart was carried out. Results: The mean height of the valved stents was 29.4G0.2 mm, with an internal diameter of 20.4G1.0 mm, and an external diameter of 25.5G0.8 mm. The procedure was successfully carried out in eight animals. In vivo evaluation showed a native mitral annulus diameter of 24.9G0.6 mm, and a mean mitral valve area of 421.4G17.5 mm 2 . ICUS showed a mild mitral regurgitation in three out of eight animals. Mean pressure gradient across the valved stents was 2.6G3.1 mmHg. Mean pressure gradient across the left ventricular outflow tract (LVOT) was 6.6G5.2 mmHg. The mean survival time was 97.5G56.3 min (survival time range was 40-180 min). One animal died due to the occlusion of the LVOT because of valved stents displacement. Postmortem evaluation confirmed correct positioning of the valved stent in the mitral position in seven out of eight animals. No atrial or ventricular lesions due to the valved stents were found. Conclusions: Off-pump implantation of a self-expandable valved stent in the mitral position is technically feasible. Further studies will assess if this procedure is also feasible in humans.

Off-pump transapical mitral valve replacement☆

European Journal of Cardio-Thoracic Surgery, 2009

Objective: Percutaneous valve replacement was recently introduced, and reports of early clinical experience have already been published. To date, this technique is limited to the replacement of pulmonary and aortic valves in a strictly selected group of patients. The aim of this study was to analyse a self-expanding valved stent for minimally invasive replacement of the mitral valve in animals. Methods: A newly designed nitinol stent was specially designed for this experimental acute study. It comprised of a left ventricular tubular stent with star shaped left atrial anchoring springs and carried a trileaflet bovine pericardial valve. A polytetrafluoroethylene membrane was sutured to envelop the atrial springs and the outside of the ventricular stent. The ventricular anchoring system was the same as in our previously reported results with a similar mitral valved stent. Seven pigs underwent minimally invasive off-pump mitral valved stent implantation. This was performed through a lower ministernotomy and a standard transapical approach under transoesophageal echocardiographic (TEE) guidance was used. Results: The valved stent is fully retrievable and precise deployment and accurate adjustment of its intra-annular position is achievable to eliminate paravalvular leakage. The deployment time ranged from 127 to 255 s and the blood loss from 70 to 220 cc. One animal died of intractable ventricular fibrillation. Mitral regurgitation in all surviving animals was minimal (trace in 5/6 and mild in 1/6 during echo examination; on the contrast ventriculogram no mitral insufficiency was observed except in one documented as mild paravalvular regurgitation). These animals remained haemodynamically stable (6/ 6) and without TEE or ventriculographic changes for 1 h. Conclusion: Implantation of a tricuspid bovine pericardial valved stent in the mitral position is feasible in pigs through a transcatheter approach. This was possible through a smaller delivery system than previously reported. Additional studies are required to demonstrate long-term feasibility, durability, and heart function. #

Functional Evaluation of the Medtronic Stentless Porcine Xenograft Mitral Valve in Sheep

Circulation, 1999

Background-Recently, renewed interest in allograft and stentless "freehand" bileaflet xenograft mitral valve replacement has arisen. The variability of human papillary tip anatomy and scarcity of donors limit allograft availability, making xenograft mitral valves an attractive alternative; however, these valves require new surgical implantation techniques, and assessment of their hemodynamics and functional geometry is lacking. Methods-Seven sheep underwent implantation of a new stentless, glutaraldehyde-preserved porcine mitral valve (Physiological Mitral Valve [PMV], Medtronic) and were studied acutely under open-chest conditions. A new method of retrograde cardioplegia was developed. Hemodynamic valve function was assessed by epicardial Doppler echocardiography. 3D motion of miniature radiopaque markers sutured to the valve leaflets, annulus, and papillary tips was measured. Six other sheep with implanted markers served as controls. Results-Both papillary muscle tips avulsed in the first animal, leaving 6 other animals. Mitral regurgitation was not observed in any xenograft valve. The peak and mean transvalvular gradients were 4.6Ϯ1.8 mm Hg and 2.6Ϯ1.5 mm Hg, respectively. The average mitral valve area was 5.7Ϯ1.6 cm 2. Valve closure in the xenograft group occurred later (30Ϯ11 ms, PϽ0.015) and at higher left-ventricular pressure (61Ϯ9 mm Hg, PϽ0.001) than in the control group; furthermore, leaflet coaptation was displaced more apically (5.6Ϯ2.2 mm, PϽ0.001) and septally (5.8Ϯ1.5 mm, PϽ0.001), and the anterolateral papillary tip underwent greater septal-lateral displacement (2.7Ϯ1.5 mm, PϽ0.001). Annular contraction during the cardiac cycle was similar in the 2 groups (xenograft 9.2Ϯ4.5% versus control 10.6Ϯ4.5% [meanϮSD; 2-factor ANOVA model]). Conclusions-Successful freehand stentless porcine mitral valve implantation is feasible in sheep and was associated with excellent early postoperative hemodynamics. Physiological mitral valve annular contraction and functional leaflet closure mechanics were preserved. Long-term valve durability, calcification, and hemodynamic performance remain to be determined in models. (Circulation. 1999;100[suppl II]:II-70-II-77.

Valved stents for transapical pulmonary valve replacement

The Journal of Thoracic and Cardiovascular Surgery, 2009

Objectives: Pulmonary valve insufficiency remains a leading cause for reoperations in congenital cardiac surgery. The current percutaneous approach is limited by the size of the access vessel and variable right ventricular outflow tract morphology. This study assesses the feasibility of transapical pulmonary valve replacement based on a new valved stent construction concept. Methods: A new valved stent design was implanted off-pump under continuous intracardiac echocardiographic and fluoroscopic guidance into the native right ventricular outflow tract in 8 pigs (48.5 AE 6.0 kg) through the right ventricular apex, and device function was studied by using invasive and noninvasive measures. Results: Procedural success was 100% at the first attempt. Procedural time was 75 AE 15 minutes. All devices were delivered at the target site with good acute valve function. No valved stents dislodged. No animal had significant regurgitation or paravalvular leaking on intracardiac echocardiographic analysis. All animals had a competent tricuspid valve and no signs of right ventricular dysfunction. The planimetric valve orifice was 2.85 AE 0.32 cm 2. No damage to the pulmonary artery or structural defect of the valved stents was found at necropsy. Conclusions: This study confirms the feasibility of direct access valve replacement through the transapical procedure for replacement of the pulmonary valve, as well as validity of the new valved stent design concept. The transapical procedure is targeting a broader patient pool, including the very young and the adult patient. The device design might not be restricted to failing conduits only and could allow for implantation in a larger patient population, including those with native right ventricular outflow tract configurations.