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At least 55 records · Page 3Linked to original sources
PubMed2003

Early results of a new mechanical tri-leaflet heart valve prosthesis--"Tricusp": an animal study.

OBJECTIVE: A new tri-leaflet mechanical heart valve made of titanium was inserted in the mitral position to evaluate early results. METHODS AND RESULTS: Five sheep were followed between 3 and 6 months (mean 4.7 months) and performed very well clinically during the follow-up period. In three of five animals a minor para-valvular leakage without hemodynamic importance was observed. The invasive pressure measurements at the end of follow-up revealed only minor transvalvular pressure differences between 1 and 4 mmHg (mean 2.4 mmHg). Similar results were obtained by echo-Doppler technique. Histological examination of the tissue around the valve showed no signs of foreign body reaction or chronic inflammatory reaction. CONCLUSION: This new tri-leaflet heart valve has shown an excellent hemodynamic performance and good tissue compatibility, and therefore may be an alternative to other currently used valve prostheses.

Animals↗
PubMed2005

Design and in vitro performance of a novel bileaflet mechanical heart valve prosthesis.

Design and in vitro performance of a novel bileaflet mechanical heart valve prosthesis are presented. The novel heart valve exhibits three main design characteristics: (i) The leaflets form a Venturi passage in open position. Thus, a beneficial pressure distribution is obtained and the leaflets are stabilised in opened position. (ii) The orifice inlet is nozzle-shaped. Flow is convectively accelerated and flow separation at the orifice inlet is avoided. (iii) The hinge design facilitates an additional axial movement of the leaflets and leads to a self cleaning effect and enhances washout of the hinges. The design of the leaflet hinges is of main importance for the functional reliability and durability of mechanical heart valves. After manufacturing first prototypes from titanium and polymeric materials the hydrodynamic performance was evaluated according to ISO 5840 and FDA guidelines. Hydrodynamic performance is comparable with the results of commonly available bileaflet mechanical heart valve prostheses. Initial durability tests showed suitable material couples for further long term studies.

Biocompatible Materials↗
PubMed2003

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

BACKGROUND: Current heart valve prostheses are constructed mimicking the native aortic valve. Special hemodynamic characteristics of the mitral valve such as a nonaxial central inflow with creation of a left ventricular vortex have so far not been taken into account. A new polycarbonaturethane (PCU) bileaflet heart valve prosthesis with special design for the mitral position is introduced, and results of animal testing are presented. METHODS AND RESULTS: After in vitro testing, 7 PCU-prostheses and 7 commercial bioprostheses (Perimount, n=4; Mosaic, n=3) were implanted in mitral position into growing Jersey calves (age 3-5 months, weight 60-97 kg) for 20 weeks. 2-Dimensional echocardiography was performed after implantation and before sacrification. Autopsy included histologic, radiographic, and electron microscopic examination of the valves. In vitro durability was proven for >15 years. After implantation 2-dimensional-echocardiography showed no relevant gradient or regurgitation of any prosthesis. Clinical course of the animals with PCU valves was excellent. In contrast, 5 of 7 calves with bioprostheses were sacrificed after 1-9 weeks because of congestive heart failure. 2-Dimensional echocardiography of the PCU valves after 20 weeks showed mild leaflet thickening with trivial regurgitation; mean gradient was 8.1+/-5.0 mm Hg (weight: 160-170 kg). The explanted PCU prostheses revealed mild calcification and no structural degeneration. All of the Perimount bioprostheses were severely calcified and degenerated after 11+/-7 weeks. One Mosaic bioprosthesis was thrombosed after 1 week, and 2 showed severe and mild-to-moderate degeneration after 4 and 22 weeks, respectively. CONCLUSIONS: Polycarbonaturethane valve prostheses with special design for mitral position show excellent hemodynamic performance and durability in vivo. Calcification and structural changes are mild compared with bioprostheses. Controlled clinical studies are planned.

Animals↗
PubMed2004

The Carbomedics aortic heart valve prosthesis: a review.

The Carbomedics bileaflet mechanical prosthesis was introduced in 1986 and until now more than 500,000 valves have been implanted. The aim of this study was to review the papers published on the Carbomedics aortic heart valve prosthesis. The Carbomedics prosthesis has a solid pyrolite carbon housing and flat leaflets of pyrolite carbon coated graphite that is impregnated with tungsten. The pyrolite carbon housing is reinforced by an outer stiffening ring composed of titanium which virtually eliminates the risk of leaflet escape. The design further enables valve rotation after implantation. The standard aortic valve prosthesis has the sewing cuff located at the outflow level of the valve cylinder. A high-performance valve, the Carbomedics TopHat valve for supraannular implantation, is a standard aortic valve prosthesis where the sewing cuff has been transferred to the inflow level of the valve cylinder. A 2 size increase in valve size can be achieved by using the TopHat valve which is very important in patient-prosthesis mismatch. With the recommended international normalised ratio (INR) level for the Carbomedics aortic heart valve prosthesis the rate of embolic and bleeding events are low. Thrombosis of a Carbomedics aortic heart valve prosthesis is rarely seen and is the result of inappropriate anticoagulation without pannus formation. The incidence of prosthetic endocarditis is very low and this is also the case for noninfectious paravalvular leakage necessitating reoperation. Intrinsic dysfunction and/or structural failure has never been reported. The total absence of intrinsic dysfunction and structural failure of the Carbomedics aortic valve prosthesis is a great advantage. Further the complication rate is very low. The TopHat, the supraannular version of this prosthesis, is a perfect solution in patient-prosthesis mismatch.

Anticoagulants↗
PubMed1976

In vivo evaluation of the Lillehei-Kaster heart valve prosthesis.

In vivo evaluation of the Lillehei-Kaster heart valve prosthesis was performed in 28 patients; 22 had undergone aortic valve replacement and 6 had had mitral valve replacement. Mean pressure gradients ranged from 6 to 53 mm Hg in aortic prostheses; valve area varied from 0.83 to 2.9 cm2. The maximum opening angle of 80 degrees was never reached in this group of patients; opening angles ranged from 57 to 74 degrees without evidence of disc malfunction. There was no correlation between the ratio of effective to geometric valve area and the degree of opening of the disc occluder. Similar results were found in the mitral valve group. Gradients ranged from 6.0 to 12.5 mm Hg and valve area from 1.6 to 2.2 cm2. The maximum opening angle was 59 to 63 degrees. It is concluded that incomplete opening of the disc occluder in pivoting-disc valves is not necessarily a sign of disc malfunction. Lillehei-Kaster valves smaller than 18 mm in internal diameter should be avoided in adults, and outflow aortoplasty for implantation of a larger prosthesis should be used in patients who have a narrow aortic root.

Adult↗
PubMed2006

Assessment of hemodynamics properties of a new-type artificial heart valve prosthesis using catheterization and echocardiography.

OBJECTIVE: The objectives of this study were to assess the hemodynamic properties of the newly developed artificial heart valve prosthesis experimentally in laboratory simulation, in an animal model, and clinically in a human model and to compare the results measured by catheterization and echocardiography. METHODS: (1) Laboratory simulation. The prosthesis was tested using a pulsatile flow simulator in the aortic position. Hydrodynamics parameters were automatically analyzed through a custom-designed data processing program. (2) Animal experiment. Six sheep subjected to mitral replacement with 21-mm-valve prosthesis were measured by open cardiac catheterization intraoperatively. Doppler echocardiography and open cardiac catheterization under dobutamine stress were performed in two sheep subjected to implantation 2.5 years ago. (3) Clinical patient observation. Observations were carried out on 14 patients with aortas replacement and 10 patients with bicuspid replacement using both doppler echocardiography and open cardiac catheterization. RESULTS: (1) Laboratory simulation. The results showed that the value of the transvalvular gradient (DeltaP) decreased with the increase of heart rate, and the values were not greater that 10 mm Hg at any given tissue annulus diameter. (2) Animal experiment. The mean DeltaP value of the six sheep was 5.2 +/- 1.7 mm Hg intraoperatively, while the corresponding DeltaP value of the two sheep 2.5 years after implantation was 6.1 +/- 0.3 mm Hg measured by open cardiac catheterization. (3) Clinical patient observation. The mean DeltaP values in the aortic position measured by catheterization and echocardiography were 6.26 approximately 4.10 and 9.42 approximately 7.48 mm Hg, respectively. The gradients in the mitral position were 2.10 approximately 1.9 and 5.28 approximately 4.10 mm Hg, respectively. CONCLUSIONS: The results demonstrate that the new-type bileaflet heart valve prosthesis only generates a relatively low transvalvar gradient and thus has good hemodynamic properties.

Adult↗
PubMed1988

Experimental evaluation of the mitroflow pericardial heart valve prosthesis. Part II. Pathologic examination.

The results of the morphologic and histopathologic examination of 37 bovine pericardial heart valve prostheses that were retrieved after experimental implantation in Chacma baboons for periods of one to twelve months are presented in this study. The implanted prostheses consisted of 33 Mitroflow valves, size 21 mm, that belonged to four different groups according to the method of preparation of the pericardium (process I to IV) and 4 commercially available Ionescu-Shiley valves, size 19 mm. All implantations were in the mitral position, except 1 Mitroflow and 1 Ionescu-Shiley prosthesis, which were implanted in the tricuspid position. Moderate or abundant noninfected thrombotic deposits were found on the cusps of 13 of the 33 Mitroflow valves (39%). The Ionescu-Shiley valves shared this tendency, perhaps to a lesser extent, for the formation of thrombus on the valve cusps. Results of transmission electron microscopy, scanning electron microscopy, and calcification analysis are also presented. In this experimental study, the authors did not identify any significant characteristics in the Mitroflow bovine pericardial heart valve prosthesis that would lead to improved or extended durability of this device over the commercially available Ionescu-Shiley bovine pericardial heart valve prosthesis and probably over any other glutaraldehyde-treated bioprosthesis. They would suggest, therefore, that any clinical investigations of the prosthesis be undertaken very cautiously.

Animals↗
PubMedDate not supplied

DeBakey Surgitool mechanical heart valve prosthesis, explanted at 32 years.

Contemporary mechanical heart value prostheses are expected to last "just about forever" or the patient's lifeline. They do however still suffer complications, some of which necessitate premature explantation. Complications today are mainly related to patient compliance with anticoagulant medication, infection and hemorrhage. The DeBakey Surgitool mechanical heart valve was the first such device to have Pyrolyte components. We present a DeBakey surgitool mechanical heart valve that was in place for 32 years! It was explanted for dysfunction related to tissue overgrowth and not to its related components. With good patient compliance, this mechanical heart valve prosthesis is an example of good prosthetic valve durability.

Aortic Valve↗
PubMed1989

[Characteristics of the adrenocortical reaction of a heart valve prosthesis during non-perfusion hypothermal protection].

Correction of acquired diseases of the heart performed under conditions of nonperfusion hypothermal defense (29-28 degrees C) in 68 patients was followed by a moderately pronounced adreno-cortical reaction reaching its maximum in the period of heating and having a tendency to decrease on the third day after operation. The absence of a pronounced relationship between the degree of growth of 11-OCS in plasma, duration of occlusion and continuation of the restorative period confirm the adequacy and effectiveness of the method of hypothermal defense in prosthesis of the heart valves.

11-Hydroxycorticosteroids↗
PubMed1996

In vitro hydrodynamic characteristics of DE-T2 biological heart valve prosthesis.

Our goal was to evaluate the DE-T2 biological heart valve prosthesis in our own pulse duplicator system. Pressure drop measurements were made across DE-T2 biological aortic valve size 21. All the pulsatile flow experiments were conducted in the Marmara Research Center pulse duplicator system. The pulsatile flow pressures were measured with Motorola MPX5100DP 9306 transducers, interfaced to Vishay 4270A, 4280, 4290, bridge amplifiers and Motorola System 4000. The valve DE-T2 had a vitellium ring with a central bar. The sewing ring was covered with bovine pericardium that continued to form the leaflets. A special incision was made in the pericardium at a 90 degrees angle to the central bar for the formation of two non-anatomical leaflets. The biological aortic valve prosthesis DE-T2 is similar to the natural aortic valve in systolic function. The closing volume is a little higher than the natural valve. Studies are continuing with the aim of diminishing the closing volume and searching for the ideal preservation solution for the pericardium.

Animals↗
PubMed1998

The Ultracor tilting disc heart valve prosthesis: a seven-year study.

BACKGROUND AND AIM OF THE STUDY: The Ultracor heart valve is a recent entry in the evolution of the tilting disc valve. This report summarizes the experience with the Ultracor valve from three European centers. METHODS: Between 1990 and 1996, 446 patients received 499 Ultracor heart valve prostheses in 450 procedures, including 225 (50.0%) aortic, 172 (38.2%) mitral and 49 (10.9%) double valve replacements. An additional four (1.0%) patients had mitral valve replacement (MVR) added to a previous aortic valve replacement (AVR) and were considered double valve replacement (DVR) patients. The total follow up was 751 patient-years (pt-yr) for AVR (mean 3.4), 440 pt-yr for MVR (mean 2.6) and 125 pt-yr for DVR (mean 2.4). Nine patients (one AVR, eight MVR) were lost to follow up, which was 98% complete. RESULTS: The actuarial survival rate, including operative mortality rate, at five years was 90% for AVR, 77% for MVR and 82% for DVR. The linearized complication rates (%/year) for AVR, MVR and DVR were: 2.1, 4.0 and 4.0 for late mortality; 0.1, 3.0 and 0.8 for thromboembolism; 0, 0.2 and 0 for thrombosis; 2.0, 1.6 and 1.6 for anticoagulant-related hemorrhage (ACH); 0.3, 0.5 and 1.6 for prosthetic valve endocarditis (PVE); and 0.5, 0.9 and 3.2 for reoperation, respectively. The actuarial rates of freedom from complications at five years were: thromboembolism, 99% for AVR and 88% for MVR; thrombosis, 100% for AVR and 99% for MVR; ACH, 91% for AVR and 94% for MVR; PVE, 99% for AVR and 97% for MVR; reoperation, 98% for AVR and 98% for MVR. No structural failure was observed. CONCLUSIONS: Seven years' experience showed the Ultracor heart valve prosthesis to be comparable with other currently used mechanical heart valves. Continued evaluation of this prosthesis is warranted in order to obtain a more extended clinical follow up.

Adult↗
PubMed2004

[Implementation of habituation theory to pulsatile somato-sounds (tinnitus): the heart valve prosthesis sound model].

OBJECTIVES: To evaluate the habituation process to mechanical heart valve prosthesis sound as a model to understand the pulsatile tinnitus or somatosound perception changes. STUDY DESIGN: Transversal descriptive. PATIENTS: One hundred and fifty patients referred to a University Hospital for one or two mechanical heart valve implantation. OUTCOME MEASURES: Questionnaire sent by mail for prosthesis sound loudness and interference in quality of life evaluation. Detection of factors related to habituation process development. RESULTS: Eighty three percent of the patients perceived their prosthesis sound continuously, while only a 17% showed high levels of annoyance. No significative differences in prosthesis type and localization were described. Anxiety was the most important factor for loudness increase. The average of visual analogical scales on sound loudness and annoyance showed mild values (3.7 and 1.9 respectively). CONCLUSIONS: Extensive medical counselling or tinnitus retraining therapy (TRT) program for most severe cases, are proposed for pulsatile tinnitus management when etiological treatment cannot be available.

Adult↗
PubMed2001

Early investigation of silver-coated Silzone heart valves prosthesis in 126 patients.

BACKGROUND AND AIM OF THE STUDY: Permanent silver (Silzone) coating of the sewing cuff of St. Jude Medical prosthetic heart valves may reduce the rate of prosthetic valve endocarditis (PVE). However, the incidence of paravalvular leaks and stroke in patients after implantation of Silzone-coated heart valve prostheses is largely unknown. METHODS: Complications were analyzed among 126 consecutive patients (78 males, 48 females; mean age 64.7 years; range: 40-80 years) who received Silzone-coated prostheses at our institution between February 1998 and December 1999. Among patients, 94 had aortic valve replacement, 29 mitral valve replacement, and three had aortic and mitral valve replacement. Concomitant cardiac procedures (mainly coronary bypass) were performed in 47 patients (37.3%). RESULTS: Hospital mortality was 1.6% (2/126) and freedom from valve-related mortality 99.2+/-0.9%. Total follow up was 137.4 patient-years, and 98.4% complete. Strokes or transitory ischemic attacks (TIAs) occurred in four cases (two strokes, two TIAs; stroke rate 1.5%/year; 95% CI 0.4-2.6%/year; stroke+TIA rate 3%/year; 95% CI 0.4-5.25%/year). There was no case of prosthetic valve dysfunction or PVE. Freedom from reoperation due to procedure-associated complications was 97.6% (one aortic dissection, two major bleeds). Paravalvular leak was detected in 19 cases, and graded trivial or mild in 17 cases (11 grade 0-I, six grade I), and moderate in two cases (grade I-II in one, grade II in one). No patient needed reoperation due to paravalvular leak. Left ventricular (LV) function was normal in 80 cases, but was impaired mildly in 20 cases, moderately in 16, and severely in eight. Bicycle exercise testing in 92 patients (73%) showed median exercise performance (81.4+/-23.9% of normal) after correction for age and weight. Cerebral magnetic resonance imaging was performed in 64 patients (50.8%); median MRI score was 2.0+/-1.8 according to a 12-scaled score system. CONCLUSION: The overall incidence of echocardiographic paravalvular leak graded more than trivial or mild was low (1.6%) in patients followed for a mean of 1.1+/-0.5 years (range: 1-27 months) after valve replacement with Silzone-coated heart valve prostheses. No patient required reoperation due to paravalvular leak; moreover, the stroke rate (1.5%/year) was low in these patients. The present data indicated no significant disadvantages or higher rate of complications related to silver coating compared with other, non-silver-coated prostheses. Future investigation is needed to determine long-term outcome.

Adult↗
PubMed2004

Early experience with percutaneous transcatheter implantation of heart valve prosthesis for the treatment of end-stage inoperable patients with calcific aortic stenosis.

OBJECTIVES: This study was done to assess the results of percutaneous heart valve (PHV) implantation in non-surgical patients with end-stage calcific aortic stenosis. BACKGROUND: Replacement of PHV has been shown to be feasible in animals and humans. We developed a PHV composed of three pericardial leaflets inserted within a balloon-expandable stainless steel stent. We report the acute and early follow-up results of the initial six PHV implantations. METHODS: An anterograde approach was used in all cases. The PHV, crimped over a 22-mm diameter balloon, was advanced through a 24-F sheath from the femoral vein to the aortic valve and delivered by balloon inflation. Clinical, hemodynamic, and echocardiographic outcomes were assessed serially. RESULTS: All patients were in New York Heart Association functional class IV. The PHV was successfully delivered in five patients. Early migration with subsequent death occurred in one patient who presented with a torn native valve. Acute hemodynamic and angiographic results showed no residual gradient, mild (three patients) or severe (two patients) aortic regurgitation, and patent coronary arteries. On echocardiography, the aortic valve area was increased from 0.5 +/- 0.1 cm(2) to 1.70 +/- 0.03 cm(2) and the aortic regurgitation was paravalvular. Marked and sustained hemodynamic and clinical improvement was observed after successful PHV implants. The first three patients died of a non-cardiac cause at 18, 4, and 2 weeks, respectively, and the other patients are alive at 8 weeks with no signs of heart failure. CONCLUSIONS: Implantation of the PHV can be achieved in patients with end-stage calcific aortic stenosis and might become an important therapeutic option for patients not amenable to surgical valve replacement.

Aged↗
PubMed1998

[Lessons from a heart valve prosthesis controversy].

Two lessons are to be learnt from the Björk-Shiley heart valve prosthesis tragedy. In the first place pharmacoepidemiologic studies are seriously hampered by recent privacy legislation. Individual patients carrying such a prosthesis cannot be traced and advised as to their health risks any more, because their legal autonomy has to be respected. This is clearly not to their advantage. In the second place the atmosphere of marketing and litigation and the increasing dependency of researchers on money from sources with conflicting interests is not conducive to a well-informed and balanced judgement of the epidemiological evidence of safety and efficacy of medical treatments.

Conflict of Interest↗