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At least 37 records · Page 2Linked to original sources
PubMed1999

Expanding the use of total mitral valve preservation in combination with implantation of the CarboMedics heart valve prosthesis.

BACKGROUND: Preservation of the mitral valve and subvalvular apparatus was introduced into the clinic in the early sixties, but for two decades the standard technique for mitral valve replacement included excision of both leaflets and their attached chordae tendineae. Lately, increased emphasis has again been placed on retention of the mitral subvalvular apparatus during valve replacement because of its role on left ventricular function. METHODS: We have preserved the valvular and subvalvular mitral apparatus, when possible, in connection with mitral valve replacement during the last seven years and the present investigation (partly prospective and partly retrospective) was done with the aim of making up the results of our mitral preservation technique. In the period between January 1990 and December 1995, 30% of the patients who underwent mitral valve replacement had complete retention of all mitral tissue. In 1996, the percentage had increased to 50, and during the first seven months of 1997, 70% of the patients had complete retention of all mitral tissue. Since January 1997, we have exclusively used the CarboMedics mitral heart valve prosthesis. A total of 56 patients were identified to have had a CarboMedics heart valve prosthesis implanted. There were 33 men and 23 women with a mean age of 63 years, range 23-77 years. Coronary bypass was a concomitant procedure in 22 patients. In seven patients, both the mitral and aortic valves were replaced. A severely altered valve with thickened and or calcified leaflets, stenotic leaflets, or shortened, retracted and thickened chordae tendineae were not a contraindication for the procedure. Calcified plaques were removed. Adhesion between anterior and posterior leaflets was treated with sharp dissection. Valve and subvalvular tissue were preserved. The leaflets were reefed within the valve-sutures and compressed between the sewing ring and the native annulus when implanting the valve prosthesis. Chordal tension on the ventricle was thereby maintained and the chordae pulled away from the valve effluent. Echocardiography with measurement of ejection-fraction was performed preoperatively during the postoperative course in case of cardiac problems and on a routine basis 1 month after surgery and at various intervals when the patient was seen in the outpatient clinic. Left ventricular outflow tract gradients were measured during the postoperative course in case of cardiac problems and routinely 1 month postsurgically. RESULTS: Five patients died in the postoperative period and one patient had transient neurological symptoms. In none of the patients was death or transient neurological symptoms a consequence of the retention of mitral leaflets with subvalvular apparatus. The remaining 51 patients were all alive at follow-up. Postoperative echocardiography demonstrated a preserved left ventricular function and a left ventricular outflow tract without obstruction. CONCLUSIONS: We find that the described technique in combination with implantation of a CarboMedics heart valve prosthesis is very useful even in patients with a severely altered valve, when preserving the mitral leaflets with subvalvular apparatus during valve replacement. The technique is without procedure related complications and preserves left ventricular function without obstructing the left ventricular outflow tract.

Adult↗
PubMed1999

Low-dose oral anticoagulation and antiplatelet therapy with St. Jude Medical heart valve prosthesis.

BACKGROUND AND AIM OF THE STUDY: Since 1986, the St. Jude Medical (SJM) mechanical heart valve prosthesis has been implanted in patients at the authors' institution. We present our experience of low-dose oral anticoagulation and antiplatelet therapy following SJM valve implantation. METHODS: Among 2,585 patients (mean age 40.3 +/- 13.5 years) living in a rural environment, 865 underwent aortic valve replacement (AVR), 1,231 mitral valve replacement (MVR) and 489 double valve replacement (DVR). All patients received 2.5 mg/day warfarin and a combination of antiaggregation therapy (dypridamole 3 x 75 mg/day plus aspirin 100 mg/day), irrespective of their prothrombin time and cardiac rhythm. RESULTS: Postoperatively, 139 adverse events occurred (51 in AVR patients, 58 in MVR, 30 in DVR). Operative mortality rate was 5.9%, 4.7% and 6.1%, respectively, in the three groups (overall mortality rate 5.4%). The most frequent cause of operative mortality was low cardiac output. During follow up, there were 88 anticoagulant hemorrhages (1.2%/patient-year (pt-yr)), 11 paravalvular leaks (0.2%/pt-yr), 52 thromboembolisms (0.7%/pt-yr), 60 mechanical valve thromboses (0.8%/pt-yr) and 78 reoperations (1.1%/pt-yr). These complications occurred in 101 patients after AVR, in 125 after MVR, and in 63 after DVR (4.2%, 3.7% and 4.6% per pt-yr, respectively). Patient age (p = 0.0004), concomitant surgery (p = 0.0017) and late valve-related complications (p = 0.0159) were statistically significant mortality factors after AVR. Previous surgery was a significant risk factor for operative mortality after MVR (p <0.05). Female gender (p = 0.0059) and age (p = 0.017) were significant risk factors for operative mortality after DVR (p <0.01). CONCLUSIONS: Following implantation of the St. Jude Medical mechanical heart valve prosthesis, a fixed dose of 2.5 mg/day warfarin and combined dipyridamole/aspirin provided satisfactory results in terms of thrombosis, embolism and bleeding.

Administration, Oral↗
PubMedDate not supplied

The porcine heart valve prosthesis.

The development of the prosthetic heart valve has led to the evolution of cardiac intensive care units, a better understanding of cardiac function and biocompatible materials, and new surgical procedures. Initial efforts with formaldehyde-fixed valves did not have long-term success. They led to the development of the stabilized glutaraldehyde process (SGP) valve and the flexible stent. The safety and efficacy of a heart valve bioprosthesis has been demonstrated through laboratory and animal experiments. Data on long-term clinical implants are needed to validate the results of these experiments.

Animals↗
PubMed1975

Pathogenesis of fungal infection on heart valve prosthesis.

Four patients with heart valve prostheses developed Candidate endocarditis. At autopsy the foci of infection were confined to patches of neoendocardium that appeared to have developed as ingrowths of host endocardium onto the sewing cloth of the artificial valve. This suggested that one mechanism of fungal infection is related to the presence of the neoendocardium rather than to the cloth or metallic substances of the valve itself. Future studies might be directed toward inhibiting the development of the neoendocardium or to agents preventing its susceptibility to infection.

Adult↗
PubMed2000

The Ultracor tilting disc heart valve prosthesis in the aortic position: mid-term follow up.

BACKGROUND AND AIM OF THE STUDY: The Ultracor valve is a recent introduction in the evolution of the tilting disc valve. This report summarizes a single surgeon's experience with the valve in the aortic position over a nine-year period. METHODS: Between 1990 and 1999, 94 patients received an Ultracor heart valve prosthesis in the aortic position. Forty-five patients (48%) had associated procedures, of which 32 (34%) were coronary artery grafts. Mean follow up was 2.6 years; total follow up was 229 patient-years. Follow up was 100% complete. RESULTS: The actuarial survival rate, including operative mortality rate, at five years was 82%. Actuarial freedom from valve-related death was 96% at five years. The linearized complication rate was 1.7%/year for late valve-related mortality, 1.7%/year for thromboembolism, 2.2%/year for anticoagulant-related hemorrhage (ACH), 1.3%/year for prosthetic valve endocarditis (PVE), and 1.7%/year for reoperation. The estimates of actuarial freedom from complications at five years were thromboembolism 89%, ACH 90%, PVE 96% and reoperation 96%. No structural failure or valve thrombosis was observed. CONCLUSION: Our experience over nine years showed the Ultracor heart valve prosthesis in the aortic position to be comparable with other currently evaluated mechanical heart valves in terms of durability and clinical results. Further study in this area should concentrate on the impact of valve type on left ventricular recovery post-implantation to provide additional information to the surgeon when selecting a valve from the plethora of choices available.

Adult↗
PubMed1981

Echocardiographic identification and analysis of function of the St. Jude medical heart valve prosthesis.

The St. Jude medical (SJM) heart valve prosthesis presents a new bi-leaflet design which in preclinical evaluation exhibited favourable haemodynamic characteristics. Therefore clinical trials started in February 1978. The entire valve is made of pyrolytic carbon which has a poor X-ray visibility and therefore an alternative for the noninvasive routine control of valvular function and postoperative follow-up had to be found. Experimental studies in a left heart simulator provided adequate echovisualisation of both leaflets, however, depending on the direction of their motion in relation to the echobeam. Identification of both leaflets and an analysis of their motion was possible with a transducer at right angles to the leaflet axis. The experimental data were confirmed by clinical observations after implantation of the SJM prosthesis in patients. Based on the information obtained, we are providing recommendations for the implantation of the SJM prosthesis in order to achieve optimal echocardiographic visualisation of the valve and its moving parts in the postoperative follow-up.

Echocardiography↗
PubMed2004

[Assessing the transvalvular gradient of a Chinese-made jiuling solid pyrolytic carbon bileaflet heart valve prosthesis].

In order to assess the transvalvular gradient of a Chinese-made Jiuling solid pyrolytic carbon bileaflet heart valve prosthesis, we determined its hydrodynamics in the laboratory and then measured the hemodynamic performance in the animals and patiens. The Jiuling prosthesis was tested in a pulsatile flow simulator in the aortic position. Six sheep subjected to mitral replacement with 21 mm Jiuling prosthesis were measured by open cardiac catheterization intraoperatively. Doppler echocardiography and open cardiac catheterization under dobutamine stress were performed in two sheep 60 months after implantation. Clinically, 14 cases of aortic valve and 10 cases of mitral valve in the patients who underwent valve replacement with Jiuling heart valve prosthesis were measured by open cardiac catheterization and Doppler echocardiopgraphy. The results showed that Juiling heart valve prosthesis had lower mean transvalvular gradient (below 10 mmHg) at any given tissue annulus diameter. In animal experiments, the transvalvular gradients of 6 sheep were 5.2 +/- 1.7 mmHg intraoperatively, and of 2 sheep 60 months after implantation were 6.1 +/- 0.3 mmHg by catheterization. In patients, the mean transvalvular gradients in the aortic position measured by means of catheterization and echocardiography were 6.26-4.10 mmHg and 9.42-7.48 mmHg; the gradients in the mitral position were 2.10-1.9 mmHg and 5.281-4.10 mmHg respectively. The above results demonstrate that Jiuling valve prosthesis has excellent hemodynamic performance.

Adult↗
PubMed2004

Introduction of a flexible polymeric heart valve prosthesis with special design for aortic position.

OBJECTIVE: Current prosthetic heart valves necessitate permanent anticoagulation or have limited durability and impaired hemodynamic performance compared to natural valves. Recently a polymeric valve prostheses with special design for mitral position demonstrated excellent in vitro and in vivo results with improved durability and no need for permanent anticoagulation. In this study, a respective flexible polymeric aortic valve is presented and in vitro and in vivo results are reported. METHODS: The aortic prosthesis (ADIAM lifescience AG, Erkelenz, Germany) is entirely made of polycarbonaturethane. The tri-leaflet flexible prosthesis mimicks the natural aortic valve and has a diminished pressure loss and reduced stress and strain peaks at the commissures. The valve underwent long-term in vitro testing and in vivo-testing in a growing calve animal model (20 weeks, 7 aortic valves) and was compared to two different commercial bioprostheses. RESULTS: The polymeric aortic heart valve substitute demonstrated excellent in vitro and in vivo hemodynamics. Five/seven animals with aortic PCU-prostheses had an excellent clinical long-term course. The explanted valves showed a variable degree of calcification. Two of the seven animals died at 27 and 77 days due to pannus overgrowth causing severe LVOTO without degeneration of the valve itself. Both animals with commercial bioprostheses had to be sacrificed because of congestive heart failure related to structural degeneration of the bioprosthesis after 10 and 30 days of implantation. There was no increased thrombogenity of the PCU valves compared to bioprostheses. CONCLUSION: The new flexible polymeric aortic valve prosthesis is superior to current bioprostheses in animal testing.

Animals↗
PubMed2005

[Reimplantation of heart valve prosthesis at the 25th week of gestation].

OBJECTIVE: Pregnancy in a woman with thrombosis of heart valve prosthesis at the 25th week of gestation and fetal death during reimplantation of prosthesis with the use of extracorporeal circulation. SUBJECT: Case report. SETTING: Department of Gynecology and Obstetrics, 2nd Medical Faculty of Charles University, Motol Hospital, Prague. SUBJECT AND METHOD: Patient L. S., 24 years old, first pregnancy, admitted to coronary heart unit at the 25th week of gestation with a blocked heart valve prosthesis, NYHA IV, left heart failure, and pulmonary edema. There was an insufficient anticoagulation therapy during pregnancy and a thrombosis of the prosthetic heart valve was suspected from that reason. Reimplantation of a prosthetic heart valve with the use of extracorporeal circulation was indicated in spite of a possible risk for the fetus. The thrombosis was confirmed during cardio surgical operation and a change of the prosthesis was successfully performed. After the patient was converted to extracorporeal circulation, bradycardia and intrauterine fetal death occurred. With regard to the patient's coagulation and circulatory instability, further management was necessary because of fetal death--termination of pregnancy by minor caesarean section was the only alternative. Six hours later an 850 g weight dead fetus was delivered. There were no serious complications during the postoperative period. CONCLUSION: Reimplantation of a prosthetic heart valve from vital indication was performed at the 25th week of gestation. After conversion of mother to extracorporeal circulation, fetal death occurred. The patients was released with satisfactory cardiopulmonal compensation.

Adult↗
PubMedDate not supplied

The Edwards MIRA heart valve prosthesis: a 2-year study.

BACKGROUND: The Edwards MIRA mechanical heart valve is designed to optimize hemodynamics, reduce thrombogenicity, and avoid mechanical failure with a special hinge mechanism. The purpose of the study was to investigate the clinical performance and postoperative hemodynamic results of the first European patients receiving Edwards MIRA mechanical heart valves. METHODS: From March 1998 to March 1999 a total of 54 Edwards MIRA valves model numbers 3600 (aortic, n = 44) and 9600 (mitral, n = 10) were implanted in 52 (36 male, 16 female; mean age 61 +/- 10.1 years) consecutive patients undergoing mechanical valve replacement in a prospective study. Follow-up of the patients including physical examination, ECG, blood tests, and Doppler were performed prior to discharge, at 6 months, at 1 year, and at least 2 years postoperatively. RESULTS: Through October 2001 a total of 172 follow-up examinations were completed (51 patients at discharge, 46 patients at 6 months, 43 patients at 12 months, 32 patients at 2 years or beyond). All patients were in NYHA class I and II at the 6-month and 2+-year follow-up. All the patients stated an improved quality of life. Hospital mortality was 1.9%. There were no complications related to anticoagulation. Mean international normalized ratio at 6 months was 3.2 (range 1.9 to 4.3); lactate dehydrogenase was slightly increased with 264 +/- 103 U/L on average (normal value 80 to 240 U/L). No signs of valvular dysfunction or paravalvular leakage were observed. Mean pressure gradients were related to valve diameter: after mitral valve replacement (size 27, 29, 31 mm: 4.8, 3.2, 2.1 mmHg); after aortic valve replacement (size 19, 21, 23, 25 mm: 12.1, 13.1, 9.3, 8.2 mmHg). CONCLUSIONS: These preliminary data suggest good hemodynamic function and a low rate of valve-related complications of the Edwards-MIRA mechanical prosthesis.

Adult↗
PubMed1995

Development, manufacturing and validation of a single-leaflet mechanical heart valve prosthesis.

A new single-leaflet mechanical heart valve prosthesis was developed and evaluated in vitro and in vivo. The basic design of the closing body is S-shaped, with the leading and trailing edges parallel to the flow direction. This closing body has an additional cross camber and a fixed axis of rotation. The bearing pins of the disc are guided within oblong through bores of the housing, resulting in a self-cleaning effect. The valve housing has a nozzle-shaped configuration in order to avoid flow separation at the inlet and to reduce the associated pressure loss. Development and optimization studies were carried out by means of upscale valve models. After manufacturing of the closing body from pyrolytic carbon and of the orifice from titanium final hydrodynamic evaluation was carried out according to ISO 5840. The results were comparable or better than for bileaflet valves, the cavitation threshold was above a left ventricular dP/dt of 5500 mmHg/sec. The excellent in vitro results were confirmed by in vivo animal studies in calves and sheep with implantation times of 12 months and six months, respectively. These studies were carried out at the RWTH Aachen and at the NIH, Washington. Without any anticoagulation treatment the valves showed excellent results, confirming the concept of a valve design based on advanced engineering techniques.

Animals↗
PubMed1999

[Low molecular heparin in a pregnant women with heart valve prosthesis].

Women with a prosthetic heart valve who wish to bear a child face a difficult choice. Continued medication with warfarin during pregnancy will offer her a reasonable good protection against thrombosis, but carries a considerable risk of teratogenic effects. Subcutaneously administered heparin is an alternative to warfarin. Standard (unfractionated) heparin has not offered sufficient protection against valve thrombosis, which may be a life-threatening complication. We were contacted by a woman who wished to become pregnant and who did not want to use warfarin if this implied a risk for the foetus. We followed a protocol using low molecular weight heparin in rather high doses. The dose was adjusted according to the results of blood test controls, which confirmed increased need for anticoagulation as the pregnancy evolved. Serial eccocardiography excluded valve thrombosis. The woman needed psychological support from her general practitioner. No complications occurred, and she gave birth to a normal child. We describe the various alternatives for anticoagulant treatment in pregnant women with mechanical heart valves. The choice of anticoagulant regimen and their consequences must be thoroughly discussed with the woman.

Adult↗
PubMed2006

Early wear development in a novel mechanical heart valve prosthesis made from polymeric materials.

BACKGROUND AND AIM OF THE STUDY: Currently, 95% of all implanted mechanical heart valve prostheses are constructed completely, or at least partially, from pyrolytic carbon. In order to develop a mechanical heart valve prosthesis made from alternative materials, a special hinge design was tested which enabled the integration of wear-resistant tribomaterials into the highly loaded hinges of leaflets. METHODS: The wear behavior of different material couples was investigated in vitro. Wear testing was performed using a specially designed durability tester that controlled the pressure difference across the closed heart valve prosthesis in a water-glycerol mixture with blood analog viscosity. Conditions were set according to FDA and ISO standards for heart valve testing. Qualitative assessment of wear behavior was performed using light microscopy and scanning electron microscopy at intervals of 10, 40, and each subsequent 50 million cycles. RESULTS: None of the investigated heart valve prostheses failed during the durability tests. Compared to the reference valve made from polymeric materials, wear especially in the hinges could be reduced to an acceptable level by integrating wear-resistant tribomaterials into the leaflets. CONCLUSION: A leaflet design which enables the integration of tribomaterials into the highly loaded hinges of leaflets leads to an optimization of wear behavior of a mechanical heart valve prosthesis made from polymeric materials. Abrasive wear in the hinges may be reduced to an acceptable level for the functionality of the heart valve prosthesis. Durability tests will be continued in order to confirm the promising wear behavior of this novel heart valve prosthesis.

Alloys↗
PubMed2006

Early wear development in a novel mechanical heart valve prosthesis made from polymeric materials.

BACKGROUND AND AIM OF THE STUDY: Currently, 95% of all implanted mechanical heart valve prostheses are constructed completely, or at least partially, from pyrolytic carbon. In order to develop a mechanical heart valve prosthesis made from alternative materials, a special hinge design was tested which enabled the integration of wear-resistant tribomaterials into the highly loaded hinges of leaflets. METHODS: The wear behavior of different material couples was investigated in vitro. Wear testing was performed using a specially designed durability tester that controlled the pressure difference across the closed heart valve prosthesis in a water-glycerol mixture with blood analog viscosity. Conditions were set according to FDA and ISO standards for heart valve testing. Qualitative assessment of wear behavior was performed using light microscopy and scanning electron microscopy at intervals of 10, 40, and each subsequent 50 million cycles. RESULTS: None of the investigated heart valve prostheses failed during the durability tests. Compared to the reference valve made from polymeric materials, wear especially in the hinges could be reduced to an acceptable level by integrating wear-resistant tribomaterials into the leaflets. CONCLUSION: A leaflet design which enables the integration of tribomaterials into the highly loaded hinges of leaflets leads to an optimization of wear behavior of a mechanical heart valve prosthesis made from polymeric materials. Abrasive wear in the hinges may be reduced to an acceptable level for the functionality of the heart valve prosthesis. Durability tests will be continued in order to confirm the promising wear behavior of this novel heart valve prosthesis.

Biocompatible Materials↗