Mitral Xenograft Research Articles

Balloon-expandable valves for degenerated mitral xenografts or failing surgical rings.

Transcatheter mitral valve-in-valve implantation (TMViVI) for the treatment of failing mitral xenografts or recurrent mitral regurgitation after surgical ring implantation is an emerging therapy for patients in need of repeated mitral valve surgery. Despite the fact that these procedures have been shown to be feasible and effective, haemodynamic data after TMViVI are still limited in the literature. Twelve patients (logES: 39.2±23.5%) were treated either by transapical (n=7) or transseptal (n=5) TMViVI, as a valve-in-valve (ViV, n=8) or valve-in-ring (ViR, n=4) implantation. Left atrial pressures (LAP), transmitral gradients and right heart haemodynamics (Swan-Ganz catheterisation) were studied before and after TMViVI. Procedural success was 100%, mitral regurgitation after TMViVI was mild in one, trace in five and absent in six patients. Thirty-day mortality was 0%. Left atrial pressures decreased significantly after valve implantation (before LAPmean/v-wave: 24.3/44.1 mmHg; after LAP/v-wave 15.9/22.1 mmHg; p<0.001) and cardiac output increased significantly. Transmitral gradients corresponded to mitral surface areas between 1.7 and 3.5 cm2, and were thus very acceptable in terms of the high surgical risk population. In conclusion, TMViVI with the balloon-expandable SAPIEN XT valve for ViV or ViR implantation is feasible with promising acute transmitral haemodynamic data. Nevertheless, sustained long-term performance remains to be demonstrated in the future.

Transcatheter access route options for treatment of degenerated mitral valve prosthesis with a balloon‐expandable biological valve

There is an ongoing discussion if valve-in-valve implantations into failing mitral xenografts should be performed only via a transapical approach. In selected high-risk patients, transcatheter valve implantation is an emerging therapy for degenerated mitral xenografts in need of repeated valve replacement. Here we describe three different strategies to treat a failing mitral biological prosthesis (Carpentier Edwards S.A.V) by implantation of a SAPIEN-XT valve, which was performed in three different patients. As access site, a transjugular/transseptal approach, a transfemoral/transseptal approach, and a transapical approach were chosen. With all three approaches, valve-in-valve implantation was successfully achieved. The acute hemodynamic effects were excellent and according to VARC there was no adverse event recorded during a 6 months follow-up. Feasibility of all three approaches is demonstrated and might be taken into consideration for treatment in various patients.

Transfemoral and Transseptal Valve-in-Valve Implantation Into a Failing Mitral Xenograft With a Balloon-Expandable Biological Valve

Valve-in-valve implantation for degenerated surgical bioprosthetic valves is becoming an increasingly accepted approach in selected high-risk patients. In the past, valve-in-valve implantations have been mainly performed in aortic position and only rarely in mitral position. We describe the case of an 81-year-old female patient with severe mitral regurgitation of a degenerated Carpentier-Edwards biological prosthesis treated by transfemoral and transseptal implantation of a SAPIEN-XT valve.

Emergency Transthoracic Transapical Mitral Valve-in-Valve Implantation

The valve-in-valve (VIV) technique is an emerging therapeutic option for patients with failure of previously implanted xenografts. We describe a balloon-expandable transthoracic transapical mitral VIV implantation in an emergency setting in a 69-year-old woman with dysfunction of the mitral bioprosthesis. Left ventricular apical access was applied. After balloon valvuloplasty, a 26-mm Edwards-Sapien transcatheter valve (Edwards Lifesciences LLC, Irvine, CA, USA) was deployed within the mitral xenograft, using rapid ventricular pacing. The transcatheter valve functioned properly postoperatively and three-dimensional echocardiography carried out 1 month later showed a well-functioning VIV prosthesis and no mitral stenosis (mitral valve area 3 cm(2) , mean gradient 3 mmHg). In this patient, VIV implantation was found to be a safe alternative to an emergent valve replacement. It might represent a suitable option to conventional procedures even among lower risk patients.

Transapical Transcatheter Mitral Valve-in-Valve Implantation in a Human

We describe a human transcatheter transapical mitral valve implant within a mitral bioprosthesis (valve-in-valve). A high-risk, 80-year-old man with symptomatic bioprosthetic mitral stenosis was positioned for anterior minithoracotomy. Left ventricular apical access was obtained. After balloon valvuloplasty, a cuffed, 26-mm Cribier-Edwards transcatheter valve (Edwards Lifesciences LLC, Irvine, CA) was deployed within the mitral xenograft, using rapid ventricular pacing. The transcatheter valve functioned properly postoperatively; however, the patient died of multiple organ dysfunction.

Minimally invasive off-pump valve-in-a-valve implantation: the atrial transcatheter approach for re-operative mitral valve replacement

This study was designed to evaluate the feasibility and haemodynamic performance of transcatheter valve-in-a-valve (VinV) implantation for failed mitral xenografts using a minimally invasive, transatrial, off-pump approach. Nine adult sheep (71.1 +/- 3.4 kg) underwent mitral valve replacement with a 25 mm bioprosthesis using standard conventional techniques. After weaning from cardiopulmonary bypass, a transcatheter 23 mm pericardial prosthesis mounted on a balloon-inflatable steel stent was deployed within the conventional xenograft. The VinV implantation (10.1 +/- 0.9 min) was performed off-pump using an antegrade transatrial approach under fluoroscopic guidance successfully in all nine sheep. Mean transvalvular gradient was 4.6 +/- 1.0 mmHg, and five of nine sheep had no paravalvular leak with two sheep each having mild and moderate one. All transcatheter prostheses were confirmed in good position on post-mortem analysis. In an in vitro model, the minimum force required to dislodge the valve was 22.5 +/- 3.0 N, which was well above the normal estimated forces generated by the left ventricle (LV). When this model was attached to a LV assist device, the VinV withstood pressure loops of 300 mmHg, without dislocation or embolization. Transatrial, transcatheter mitral VinV implantation is feasible off pump. This is a truly minimally invasive concept to treat patients with failed xenografts using a right lateral minithoracotomy.

Minimally invasive off-pump valve-in-a-valve implantation – the atrial transcatheter approach for re-operative mitral valve replacement

Aims This study was designed to evaluate the feasibility and haemodynamic performance of transcatheter valve-in-a-valve (VinV) implantation for failed mitral xenografts using a minimally invasive, transatrial, off-pump approach. Methods and results Nine adult sheep (71.1 ± 3.4 kg) underwent mitral valve replacement with a 25 mm bioprosthesis using standard conventional techniques. After weaning from cardiopulmonary bypass, a transcatheter 23 mm pericardial prosthesis mounted on a balloon-inflatable steel stent was deployed within the conventional xenograft. The VinV implantation (10.1 ± 0.9 min) was performed off-pump using an antegrade transatrial approach under fluoroscopic guidance successfully in all nine sheep. Mean transvalvular gradient was 4.6 ± 1.0 mmHg, and five of nine sheep had no paravalvular leak with two sheep each having mild and moderate one. All transcatheter prostheses were confirmed in good position on post-mortem analysis. In an in vitro model, the minimum force required to dislodge the valve was 22.5 ± 3.0 N, which was well above the normal estimated forces generated by the left ventricle (LV). When this model was attached to a LV assist device, the VinV withstood pressure loops of 300 mmHg, without dislocation or embolization. Conclusion Transatrial, transcatheter mitral VinV implantation is feasible off pump. This is a truly minimally invasive concept to treat patients with failed xenografts using a right lateral minithoracotomy.

Valve-in-a-Valve Concept for Transcatheter Minimally Invasive Repeat Xenograft Implantation

This study sought to evaluate the feasibility of minimally invasive transapical repeat valve-in-a-valve (VinV) implantation. Reoperative heart valve replacement for degenerated xenografts is associated with an increased surgical risk. Conventional Carpentier Edwards porcine aortic (n = 5) and mitral (n = 2) valve prostheses were implanted in 7 pigs. Transapical VinV implantation of a pericardial xenograft fixed within a 23-mm stainless steel, balloon expandable stent (Cribier Edwards, Edwards Lifesciences, Irvine, California) was then performed under fluoroscopic and echocardiographic visualization on the beating heart with ventricular unloading via cardiopulmonary bypass and rapid ventricular pacing. Valve deployment was successfully performed in all cases. The radiopaque marking within the stent of the conventional aortic or mitral xenograft allowed for optimal positioning of the stent-delivered valve. All valves were firmly positioned without any migration. There were neither paravalvular nor transvalvular leaks, and good hemodynamic function was observed in all cases. All coronary arteries remained patent. Positioning and function were confirmed by autopsy in all animals. The VinV concept is promising for minimally invasive beating heart repeat aortic or mitral valve replacement, using a stent-fixed sutureless prosthesis.

Hemodynamic performance of an unstented xenograft mitral valve substitute

Objective: Stentless mitral xenografts offer potential clinical benefits because they mimic the normal bileaflet mitral valve. How best to implant them and their hemodynamic performance and durability, however, remain unknown. Methods: A stentless porcine mitral xenograft valve (Medtronic physiologic mitral valve) was implanted in 7 sheep with papillary muscle sewing tubes attached with transmural left ventricular sutures. Radiopaque markers were inserted on the leaflets, annular cuff, papillary tips, and left ventricle. After 10 ± 5 days, the animals were studied with biplane videofluoroscopy to determine 3-dimensional marker coordinates at baseline and during dobutamine infusion. Transesophageal echocardiography assessed mitral regurgitation and valvular gradients. Mitral annular area was calculated from the annular markers. Physiologic mitral valve leaflet and annular dynamics were compared with 8 native sheep valves. Results: Average mitral regurgitation grade at baseline was 1.2 ± 1.0 (range, 0-4), and the mean transvalvular pressure gradients were 3.6 ± 1.3 and 6.2 ± 2.2 mm Hg during baseline and dobutamine infusion, respectively. Xenograft mitral annular area contraction throughout the cardiac cycle was reduced (6% ± 6% vs 13% ± 4% for physiologic mitral valve and control valve, respectively; P =.03). Physiologic mitral valve leaflet geometry during closure differed from the native valve, with the anterior leaflet being convex to the atrium and with little motion of the posterior leaflet. Three animals survived more than 3 months; good healing of the annular cuff and papillary muscle tubes was demonstrated. Conclusion: This stentless xenograft mitral valve substitute had low gradients at baseline and during stress conditions early postoperatively, with mild mitral regurgitation. Preliminary analysis of healing characteristics appeared favorable at 3 months. Additional studies are needed to determine long-term xenograft mitral valve performance and resistance to calcification.J Thorac Cardiovasc Surg 2002;124:541-52

Biological valves beyond fifteen years: The wessex experience

Between 1975 and 1979, 443 biological valves (298 Carpentier-Edwards, 134 homograft, and 11 Hancock valves) were implanted in 415 patients (age, 16 to 77 years; mean, 59 years) with an operative mortality of 2.9%. Total follow-up was 4,248 patient-years. Overall event-free survival was 60% +/- 1.5% (standard deviation) at 10 years and 29% +/- 1.4% at 15 years. Ten-year and 15-year event-free survival were 72% +/- 3.4% and 41% +/- 3.3% for aortic homografts, 62% +/- 3% and 33% +/- 2.8% for isolated aortic xenografts, and 43% +/- 3.5% and 14% +/- 3.0% for isolated mitral xenografts. Freedom from structural valve degeneration was 87% +/- 1.3% and 63% +/- 2.5% for all patients at 10 and 15 years, respectively, 86% +/- 2.7% and 58% +/- 4.1% for aortic homografts, 93% +/- 1.8% and 76% +/- 5.1% for aortic xenografts, and 75% +/- 4.0% and 47% +/- 7.4% for mitral xenografts. Of the 110 remaining patients, echocardiography was performed in 61 patients (23 aortic xenograft, 24 aortic homograft, 9 mitral xenograft, and 5 tricuspid xenograft) between 14 and 17 years after implantation. An early diastolic murmur was heard in 57% of all aortic valve replacements (AVRs) 62.5% of homograft AVRs, and 52% of xenograft AVRs. Echocardiographically, aortic regurgitation was detected in 79%, 83%, and 74% of all AVRs, homografts, and xenografts, respectively. Aortic stenosis was present clinically in 11% of all AVRs, 4% of homograft AVRs, and 17% of xenograft AVRs.(ABSTRACT TRUNCATED AT 250 WORDS)

In Vitro Analysis of Performance of Porcine Xenografts with Inward Bending of Stent Posts: Real-time Measurement of Valve Orifice Area Using an Area Meter

The influence of inward bending of the stent posts on bioprosthetic valve function was assessed in a hydromechanical simulation of the left heart. A Carpentier-Edwards mitral xenograft (31 mm) and an aortic xenograft (27 mm) were used. Valve function was evaluated before and after the stent posts were bent inward 15 degrees by suture constriction of the tops of the three posts. To evaluate the effects of the stent-post deformity on valve performance, the mean transvalvular pressure drop during steady flow, the bioprosthetic valve orifice area, and the maximum valve opening and closing speeds during pulsatile flow were measured using an area meter. Steady-flow data showed identical transvalvular pressure drops, and no significant difference in valve performance was detected in the pulsatile-flow study under the two experimental conditions (i.e., normal valve and deformed valve). We conclude that a 15-degree inward bending of the stent posts does not appreciably affect valve function in vitro.

生体弁による僧帽弁置換術後の再手術

生体弁による僧帽弁置換術後の再手術

Perforation of muscle shelf of right coronary cusp causing acute regurgitation of porcine mitral xenograft

Perforation of muscle shelf of right coronary cusp causing acute regurgitation of porcine mitral xenograft

Hemodynamic evaluation of the Angell-Shiley porcine xenograft

The Angell-Shiley porcine xenograft was evaluated in 48 asymptomatic subjects who underwent cardiac catheterization an average of 14 months after operation. Nineteen patients had mitral and 29 had aortic valve replacement. The average mitral valve gradient was 8 +/- 3 mm Hg and the average effective orifice area was 1.8 +/- 0.6 cm2. The average aortic valve gradient was 22 +/- 7 mm Hg and the average effective orifice area was 1.2 +/- 0.3 cm2. During supine leg exercise, the average mitral valve gradient increased to 12 +/- 4 mm Hg (p less than 0.001) and the average aortic valve gradient increased to 27 +/- 8 mm Hg (p less than 0.001) compared to findings at rest. On the basis of data obtained with a regression analysis model, there is a high probability that an Angell-Shiley aortic xenograft with a stent diameter less than 25 mm will have a postoperative effective orifice area of less than 1 cm2, and that an Angell-Shiley mitral xenograft with a stent diameter less than 30 mm will have a postoperative effective orifice area of less than 1.5 cm2. Our data suggest that the Angell-Shiley xenograft has suboptimal hemodynamic performance in stent sizes less than 30 mm in the mitral position and less than 25 mm in the aortic position.

Factors affecting performance and thromboembolism after porcine xenograft cardiac valve replacement

Long-term durability and the need for anticoagulation in conjunction with the use of porcine valves remain questionable. We analyzed valve dysfunction and thromboembolism in 325 adult (older than 20 years) and 31 pediatric survivors who received 407 porcine xenograft valves from June, 1974, to September, 1980 (46% of all valve replacements). Valves at risk in the adults were 216 aortic, 138 mitral, and 22 tricuspid; in children, 14 aortic, eight mitral, seven pulmonary, and two tricuspid. Mean follow-up was 38 (9 to 85) months. Twenty-seven valved conduits also were followed up for 9 to 85 (mean 52) months. Two late deaths in children resulted from dysfunction and another from endocarditis. One late death in an adult was caused by embolism. The other 36 deaths in the entire group were not valve related. Dysfunction requiring reoperation at 12 to 37 months occurred in eight of 325 adults (six mitral, one aortic, and one tricuspid). Dysfunction was due to recurrent endocarditis in six and to primary tissue failure in two (both older than 35 years of age); all survived reoperation. However, in children, severe dysfunction due to primary tissue failure occurred in seven (23%) cardiac valves, necessitating replacement at 21 to 48 months, and three of 27 conduits had to be replaced at 39 to 70 months. Thromboembolism occurred in six adults with mitral xenografts but none with aortic or tricuspid valve. Four of the patients with thromboemboli (one of whom died) were among 16 who had atrial fibrillation and no warfarin, but aspirin and persantine (11.7%/patient-year) and two were among 14 with sinus rhythm on no medication. No thromboembolism occurred in patients with mitral xenografts who were in sinus rhythm and receiving antiplatelet agents or in those with atrial fibrillation receiving warfarin. This experience indicates a high incidence of relatively early failure of porcine xenograft cardiac valves in children and young adults but excellent medium and long-term performance in older adults, in whom severe dysfunction occurred mainly with recurrent endocarditis. Thromboembolism occurred primarily in patients with mitral replacement especially with atrial fibrillation and no anticoagulants.

An appreciation of the new St. Jude valvular prosthesis

Beginning in March, 1978, 88 patients have had cardiac valve replacements with St. Jude prostheses. There were 26 males and 62 females, aged 6 to 80 years (mean 60). Single valve replacement was done in 67. Double valve replacement was done in 21; 12 of them had two St. Jude valves and nine had a different second valve. There were 57 mitral and 43 aortic valves replaced. Thirty-six patients had concomitant aorta-coronary bypass, and six others had additional cardiac procedures. All patients have been followed for a total of 807 patient-months (mean 9 months). Seventy-nine have been receiving sodium warfarin and seven are not receiving anticoagulants. There has been one embolic episode. There are no valve failures to date. Early mortality is 2.3% and late mortality, 5.7%; no death was valve related. Fifty-three survivors have improved by two or more N.Y.H.A. classifications. Fifty-four valves studied postoperatively at rest, during pacing, and during isoproterenol infusion have demonstrated significantly better hemodynamic performance than have mitral porcine xenografts studied in an identical manner (p < 0.05). Phonocardiography, M-mode and two-dimensional echocardiography, and cinefluoroscopy, carried out in 18 patients, have proved to be reliable noninvasive techniques for long-term follow-up. This experience indicates that the St. Jude prosthesis offers an excellent and predictable alternative in the surgeon's decision-making concerning valve choices.

Hemodynamic factors that affect calculated orifice areas in the mitral hancock xenograft valve.

From June 1974 to December 1978, 714 Hancock valves have been placed in 605 patients. One hundred seventy-five patients with a mitral xenograft have been restudied. The results were questionable due to the wide scatter and disparity between the calculated and the theoretical orifice of each valve size. To elucidate these differences, the hemodynamic data of 40 isolated, normal functioning mitral Hancock valves were reviewed. Early, middle and late diastolic mitral valve gradients were measured by planimetry and their corresponding flows were estimated by angiography. The paired data were fitted to exponential functions and specific lines for each Hancock valve size were obtained. By superimposing Gorlin's pressure and flow curves on these lines, the instantaneous effective orifice for each Hancock valve can be determined. We concluded that 1) the Hancock valve effective orifice is flow related and always lower than its theoretical opening; 2) normal function frequently cannot be firmly established by the mean effective area; and 3) the nomogram described may help in determining the time-related variations of a particular valve.