Hemodynamic and hemolytic features of the St. Jude Medical valve prostheses

We performed valvular replacement in 86 cases (108 valves, 43 males, 43 females) from July 1978 to July 1981 with St. Jude Medical valves which utilize two discs made of pyrolytic carbon and employ a bileaflet central opening system. Ages ranged from 13 to 68 years (average 42.3). For all cases in this study, we performed anti-coagulant therapy. The incidence of thromboembolic complication was zero. With regard to postoperative clinical evaluation on valve function and chronic hemolysis, we compared the cases of St. Jude Medical valves with those of Starr-Edwards (S.E.) valves (aortic: Model 2320, mitral: Model 6400), Carpentier-Edwards (C.E.) valves and cases of open mitral commissurotomy. As for valve function such as left atrioventricular diastolic pressure gradient, mitral effective orifice area both at rest and on exercise, the St. Jude Medical valve yielded best results. Next was the C.E. and third was the S.E. The results of the St. Jude Medical valve group and those of the open mitral commissurotomy group were equivalent. In comparison with ball type cardiac valve prostheses and bioprostheses, the St. Jude Medical valve has excellent hemodynamic characteristic. Concerning hemolysis, the St. Jude Medical was below only the C.E., however the degree of hemolysis was so low that the St. Jude Medical valve holds great promise as central flow mechanical valve prostheses.     

Effect of mechanical aortic valve orientation on coronary artery flow: comparison of tilting disc versus bileaflet prostheses in pigs

OBJECTIVE: Orientation for optimal systolic performance of tilting disc and bileaflet aortic valves was defined in previous studies. The present study investigates the influence of valve orientation on coronary artery flow in an animal model. METHODS: A rotation device holding either a Medtronic Hall tilting disc (n = 4; Medtronic, Inc, Minneapolis, Minn), a St Jude Medical bileaflet (n = 4; St Jude Medical, Inc, St Paul, Minn), or a Medtronic Advantage bileaflet (n = 3) aortic valve was implanted. The device allowed rotation of the valve without reopening the aorta. Flow through the left anterior descending coronary artery was measured preoperatively and at normal versus high cardiac output after weaning from extracorporeal circulation. Measurements were performed at the best and worst hemodynamic position, as defined previously. RESULTS: Coronary flow rates were similar in all animals preoperatively (26 +/- 4.1 mL/min). After aortic valve replacement, left anterior descending flow increased significantly to 58.2 +/- 10.6 mL/min. Highest flow rates at normal cardiac output were found in the optimum orientation, especially for the Medtronic valves (Medtronic Hall, 64 +/- 8.7 mL/min; Medtronic Advantage, 64.6 +/- 11.6 mL/min; St Jude Medical, 48.3 +/- 10.3 mL/min), whereas the worst position demonstrated significantly lower left anterior descending flow, with no differences among valves (Medtronic Hall, 37.5 +/- 1.3 mL/min; St Jude Medical, 35.7 +/- 10.7 mL/min; Medtronic Advantage, 39.8 +/- 10 mL/min). Left anterior descending artery flow increased significantly with higher cardiac output. CONCLUSIONS: Coronary blood flow was significantly influenced by mechanical aortic valve implantation and the orientation of prostheses. For both valve designs, the previously defined optimum orientation with respect to pressure gradients and turbulence demonstrated the highest left anterior descending flow rates. Even in its optimum orientation, the St Jude Medical valve showed significantly lower coronary flow than the other valves.     

Flow Characteristics of the St. Jude Prosthetic Valve: An In Vitro and In Vivo Study

The St. Jude cardiac prosthetic aortic valve was evaluated in vitro and in vivo in an attempt to establish flow characteristics and to correlate them with clinical findings. In vitro, a fluid vehicle (6% Polyol V-10, 32°C) with viscosity similar to blood (0.035 dyne-sec/cm²) was used under conditions of steady flow through a flow chamber simulating the aortic root. Gradient, velocity, and shear stress were measured 5.79 mm, 26.79 mm, 44.79 mm, and 77.79 mm downstream from 25-mm and 27-mm valves using a laser-Doppler anemometer. At 417 ml/sec, the valve gradient was 6.2 mmHg with the 25-mm valve, and 5.2 mmHg with the 27-mm prosthesis. Velocity was maximum at the orifice center, and wall shear stress was low (maximum 600 dyne/cm²). In vivo, six patients with 25-mm St. Jude aortic valves were studied within 48 hours after surgery to determine cardiac output, valve flow, and gradient. The gradient was 3.3 ± 1.9 mmHg (M ± SD) at 249 ± 96 ml/sec and the effective valve area was as large as the geometric area (2.58 vs. 3.09 cm²). Thus, flow through the St. Jude valve is unobstructed and central, has low turbulence, and achieves optimal effective valve area for a given available orifice area.     

Follow-up Assessment of St. Jude Medical Prosthetic Valve in the Tricuspid Position: Clinical and Hemodynamic Results

Seven patients underwent postoperative right heart catheterization following implantation of the St. Jude Medical prosthetic valve in the tricuspid position. Six patients were in atrial fibrillation at catheterization, and 1 was in normal sinus rhythm. At postoperative catheterization, the mean right atrial pressure ranged between 4 and 16 mm Hg (mean, 9.7 mm Hg); right ventricular systolic pressure was normal in 1 patient, mildly elevated (less than 50 mm Hg) in 4 patients, and moderately elevated (65 and 70 mm Hg) in 2. The cardiac output ranged between 3.0 and 7.0 L/min (mean, 4.2 L/min). There was no end-diastolic gradient across the St. Jude Medical prosthesis in 6 patients. The other patient had a gradient of 2 mm Hg across the valve when cardiac output was 7.0 L/min. On fluoroscopy, both discs demonstrated full excursion in all patients.These data demonstrate that a normally functioning St. Jude Medical valve in the tricuspid position does not create obstruction to forward flow, and they support use of this prosthesis in patients with tricuspid valve disease.     

Comparison of noninvasive techniques in evaluation of the Bj?rk-Shiley and the St. Jude Medical valve prostheses in mitral position

Pressure gradients and left ventricular function were assessed by Doppler echocardiography in 50 patients with Bj?rk-Shiley mitral valve and 50 patients with St. Jude Medical valve prosthesis. There was correlation between pressure gradient and valve size, and between effective valve orifice area and valve size for St. Jude Medical valve. These correlations were not found in Bj?rk-Shiley valve. Clinical improvement and cardiac function were quite satisfactory in 20 patients with Bj?rk-Shiley valve and in 32 patients with St. Jude Medical valve whose pressure gradients were less than 10 mmHg. Twenty eight of 50 patients with Bj?rk-Shiley valve and 42 of 50 patients with St. Jude Medical valve showed good response to the exercise test. Eight patients underwent reoperation because of unacceptably high gradient caused by thrombus and pannus formation. The patients who show high pressure gradient across the valve prosthesis should be followed up cautiously.     

Clinical assessment of the St. Jude medical cardiac prosthesis. A 5-year experience

Mechanical prosthetic valves have established their long-term durability, but the incidence of thromboembolism has been less satisfying. Therefore, the search for the perfect valve continues. The choice of replacing a cardiac valve with a prosthetic valve is based upon its hemodynamics, durability, thromboembolic and hemolytic characteristics. The hemodynamic assessment of the St. Jude Valve demonstrates that it performs well in the aortic, mitral, and tricuspid positions. The central bileaflet flow design leads to minimal gradients, even in the small valves which make it ideal for its use in children. The purpose of its all-pyrolite construction is to decrease the incidence of thromboembolism. Replacement of heart valves with the St. Jude Medical prosthesis was initiated in April, 1979. An analysis of all patients undergoing valve replacement between April 1, 1979, and June 1, 1984, was carried out to assess the durability, incidence of thrombosis, and thromboembolic as well as other complications.     

An in vitro assessment by means of laser Doppler velocimetry of the medtronic advantage bileaflet mechanical heart valve hinge flow

OBJECTIVE: The aim of this study was to evaluate the hinge flow field characteristics of the Medtronic Advantage bileaflet valve and compare them with the flow fields of the St Jude Medical standard valve. The present study provides laser Doppler velocimetry results for the Advantage and St Jude Medical valves to make a direct comparison of the flow fields of the 2 valve designs. This study aids in determining the preclinical efficacy of Medtronic's new bileaflet valve hinge design. METHODS: Two-dimensional laser Doppler velocimetry was used to measure the velocities in the hinge regions of size 29 Medtronic Advantage and St Jude Medical standard bileaflet valve designs. Exact dimensional models of the bileaflet valves, including the hinge regions, were cast from transparent plastic materials to conduct these measurements under simulated physiologic conditions. Laser Doppler velocimetry measurements were conducted under physiologic conditions, with the valves placed in the mitral position of a pulsatile flow loop. Measurements were taken at several elevation levels in the hinge region. Multiple measurement locations obtained in each plane provided a grid work by which the flow fields could be detailed. RESULTS: Velocity measurements obtained for each valve design in the hinge recess were used to reconstruct the flow fields. For the Advantage valve, the peak velocities during leakage flow in the hinge at zero depth, one-third depth, and two-thirds depth levels into the hinge recess were 0.9, 1.6, and 1.8 m/s, respectively. Corresponding values for the St Jude Medical valve were 1.3, 1.6, and 2.1 m/s, respectively. From the reconstructed flow fields, the flow patterns seen within the 2 hinge designs exhibited similar features, with more dynamic flow patterns observed in the Advantage hinge during the forward flow phase. CONCLUSIONS: The present study demonstrated that the hinge flow dynamics of the Advantage bileaflet design were similar to those of the St Jude Medical hinge design. The velocities within the hinge were slightly higher for the St Jude Medical valve but not significantly different. There appears to be more dynamic flow through the hinge of the Advantage valve during the forward flow phase.     

In vivo hemodynamics of prosthetic St. Jude Medical and Ionescu-Shiley heart valves analyzed by computer

Using a method of our own design, we evaluated intraoperatively the function of prosthetic heart valves. The changing hemodynamics induced by a stress test were assessed by simultaneously measuring the mean transvalvular pressure gradient and the stroke volume. The effective orifice area (EOA) of the valves was determined for each stroke by computer analysis, and this value was compared with the actual orifice area. Data were collected from 19 patients undergoing aortic or mitral valve replacement or both with 17 St. Jude Medical and 12 Ionescu-Shiley valves. The mean pressure gradient increased with tachycardia and an increase in mean left atrial pressure in the mitral position, but decreased with a decrease in cardiac output and peak left ventricular pressure in the aortic position. The St. Jude Medical valve had a smaller mean pressure gradient than the Ionescu-Shiley bioprosthesis. For both valves, the EOA increased with valve size. The St. Jude Medical valve had a greater EOA than the Ionescu-Shiley bioprosthesis, regardless of the valve size (p less than 0.005). However, the performance of prosthetic leaflets was better with the Ionescu-Shiley bioprosthesis than with the St. Jude Medical mechanical valve (p less than 0.001). This method involving computer analysis of each cardiac cycle proved to be useful for evaluating prosthetic heart valve function in the presence of changing hemodynamics.     

Mitral and mitro-aortic valve replacement with Sorin Bicarbon valves compared with St. Jude Medical valves

OBJECTIVE: We assessed the clinical results of two bileaflet mechanical valves: the St. Jude Medical (SJM) and the Sorin Bicarbon (Sorin Bicarbon) used either in single mitral valve replacement (MVR) or in double, aortic and mitral, valve replacement (DVR). METHODS: Between September 1990 and November 1995, 217 patients received either a St. Jude Medical (n=134) or a Sorin Bicarbon (n=86): 136 mitral valve replacement with 83 St. Jude Medical and 53 Sorin Bicarbon and 84 double valve replacement with 51 St. Jude Medical and 33 Sorin Bicarbon. There was no difference between both St. Jude Medical and Sorin Bicarbon cohorts in respect of mitral valve physiopathology, etiology of valve disease, associated lesions, echocardiographic and hemodynamic data. The only significant preoperative difference was the age of patients within the double valve replacement group and the size of implanted valves within the mitral valve replacement group. Follow-up was 100% complete with a mean of 39+/-18 months, ranging between 6 and 68 months. The total follow-up was 657 patient-years (pt-y): 396 pt-y in the mitral valve replacement group and 274 pt-y in the double valve replacement group. RESULTS: Hospital mortality (St. Jude Medical: 2.2%; Sorin Bicarbon: 6.9%) and late mortality (St. Jude Medical: 8.4%; Sorin Bicarbon: 6.3%) were not significantly different. Ten deaths were considered valve-related (St. Jude Medical 6, Sorin Bicarbon 4). The estimated 4-yr overall survival, including hospital mortality, was for St. Jude Medical--mitral valve replacement: 89+/-4% and St. Jude Medical--double valve replacement: 93+/-4%, and for Sorin Bicarbon--mitral valve replacement: 87+/-5% and Sorin Bicarbon--double valve replacement: 91+/-5%. The linearized incidence (% per pt-y) of valve-related complications was 6.39 in the St. Jude Medical cohort and 9.2 in the Sorin Bicarbon cohort. The linearized incidence (% pt-y) of the prevalent complication, valve thromboembolism and bleeding, was for St. Jude Medical-mitral valve replacement: 3.41, St. Jude Medical--double valve replacement: 3.16 and for Sorin Bicarbon--mitral valve replacement: 2.17 and Sorin Bicarbon--double valve replacement: 3.67. The differences between each group of an estimated 4-yr freedom from combined thromboembolism and bleeding were not significant (St. Jude Medical--mitral valve replacement: 90+/-4%, St. Jude Medical--double valve replacement: 84+/-6%, and for Sorin Bicarbon--mitral valve replacement: 94+/-3% and Sorin Bicarbon--double valve replacement: 75+/-17%). CONCLUSIONS: In this clinical non-randomized study, there was no evidence of any significant difference between St. Jude Medical and Sorin Bicarbon valves over a 4-yr follow-up.     

Entrapment of Leaflet of St. Jude Medical Cardiac Valve Prosthesis by Miniscule Thrombus: Report of Two Cases

Two patients with dysfunction of the St. Jude Medical cardiac valve prosthesis, one in the aortic and one in the mitral position, are presented. In both, one of the valve leaflets was jammed by a very small thrombus that fixed the leaflet in a semiclosed position. Neither patient received anticoagulation postoperatively. Because of the pathological findings in these 2 patients, anticoagulation for patients with a St. Jude Medical valve prosthesis is recommended for life.     

Ten-year follow-up after valve replacement with the St. Jude Medical prosthesis in children

Since 1979, 50 children, 4 months to 15 years of age, have successfully undergone cardiac valve replacement with the St. Jude Medical prosthesis (St. Jude Medical, Inc., St. Paul, Minn.). There were 24 boys and 26 girls. The valve replaced was mitral in 28 children, aortic in 15, mitral and aortic in 1, and mitral and tricuspid in 1. A left-sided tricuspid valve was replaced in 3 children. Anticoagulant therapy was maintained in all children; 40 children were treated with warfarin, whereas 10 children who underwent aortic or mitral valve replacement were on a regimen of aspirin combined with dipyridamole. The follow-up period, comprising 224 patient-years, ranged from 1 to 10 years. There were four valve-related complications: one from thromboembolism, two from valve thrombosis, and the other one from prosthetic valve endocarditis. Actuarial rate free from all valve-related complications at 10 years was 84.7%. There were four late deaths: one from valve thrombosis and the others from non-valve-related complications. Actuarial survival rate at 10 years was 90.8%. All surviving children are in functional class I, and no child so far has needed replacement of a prosthesis because of somatic growth. These results indicate that the St. Jude Medical prosthesis is a cardiac valve substitute of choice for valve replacement in children.     

St. Jude Medical prosthetic aortic valve malfunction due to pannus formation.

According to the literature, the incidence of pannus formation with the St. Jude Medical prosthetic aortic valve has been reported at 0.03% and 0.14% (per patient-year), with no case report of St. Jude Medical prosthetic aortic valve malfunction due to pannus formation. Between 1980 and 1999, 1,186 patients underwent aortic valve replacement at our institute. We encountered 2 aortic valve malfunctions due to pannus formation, including the case of a 53-year-old woman who suffered a St. Jude medical aortic valve malfunction 13 years after the initial operation. A second aortic valve replacement was successful and the postoperative course was uneventful. The possibility of pannus formation on St. Jude Medical aortic valves must thus be considered and its mechanism clarified.     

Assessment of effective orifice area of prosthetic aortic valves with Doppler echocardiography: an in vivo and in vitro study

OBJECTIVES: We sought to evaluate the Doppler assessment of effective orifice area in aortic prosthetic valves. The effective orifice area is a less flow-dependent parameter than Doppler gradients that is used to assess prosthetic valve function. However, in vivo reference values show a pronounced spread of effective orifice area and smaller orifices than expected compared with the geometric area. METHODS: Using Doppler echocardiography, we studied patients who received a bileaflet St Jude Medical valve (n = 75; St Jude Medical, Inc, St Paul, Minn) or a tilting disc Omnicarbon valve (n = 46; MedicalCV, Incorporated, Inver Grove Heights, Minn). The prosthetic valves were also investigated in vitro in a steady-flow model with Doppler and catheter measurements in the different orifices. The effective orifice area was calculated according to the continuity equation. RESULTS: In vivo, there was a wide distribution with the coefficient of variation (SD/mean x 100%) for different valve sizes ranging from 21% to 39% in the St Jude Medical valve and from 25% to 33% in the Omnicarbon valve. The differences between geometric orifice area and effective orifice area in vitro were 1.26 +/- 0.41 cm(2) for St Jude Medical and 1.17 +/- 0.38 cm(2) for Omnicarbon valves. The overall effective orifice areas and peak catheter gradients were similar: 1.35 +/- 0.37 cm(2) and 25.9 +/- 16.1 mm Hg for St Jude Medical and 1.46 +/- 0.49 cm(2) and 24.6 +/- 17.7 mm Hg for Omnicarbon. However, in St Jude Medical valves, more pressure was recovered downstream, 11.6 +/- 6.3 mm Hg versus 3.4 +/- 1.6 mm Hg in Omnicarbon valves (P =.0001). CONCLUSIONS: In the patients, we found a pronounced spread of effective orifice areas, which can be explained by measurement errors or true biologic variations. The in vitro effective orifice area was small compared with the geometric orifice area, and we suspect that nonuniformity in the spatial velocity profile causes underestimation. The St Jude Medical and Omnicarbon valves showed similar peak catheter gradients and effective orifice areas in vitro, but more pressure was recovered in the St Jude Medical valve. The effective orifice area can therefore be misleading in the assessment of prosthetic valve performance when bileaflet and tilting disc valves are compared.     

Rest and exercise hemodynamics of 20 to 23 mm allograft, Medtronic Intact (porcine), and St. Jude Medical valves in the aortic position

Doppler echocardiography was used to measure gradients and valve areas at rest and after supine bicycle exercise in 35 patients with valve replacements 20 to 23 mm in size. Thirteen patients with a St. Jude Medical valve (St. Jude Medical, Inc., St. Paul, Minn.) were matched to 13 patients with an allograft valve, and seven patients with a Medtronic Intact (porcine) valve (Medtronic, Inc., Minneapolis, Minn.) to seven patients with an allograft valve. Patients were matched for age, sex, valve size, body surface area, and left ventricular systolic function. There was no statistically significant difference between the matched groups for body surface areas, resting cardiac output, exercise heart rate, or workload achieved. Mean pressure gradient was higher for St. Jude Medical than for allograft groups, both at rest (11.8 +/- 6.67 mm Hg for St. Jude Medical versus 6.67 +/- 2.98 mm Hg for allografts) and after exercise (16.4 +/- 8.47 mm Hg versus 9.7 +/- 3.94 mm Hg), but the differences were of borderline significance (p = 0.016 and 0.027, respectively). Valve area at rest was similar for both devices (1.4 +/- 0.45 cm2 for St. Jude Medical versus 1.8 +/- 0.56 cm2 for allograft; p greater than 0.1). There were highly significant differences between patients with Intact and those with allograft valves for resting mean pressure gradient (19.3 +/- 4.23 mm Hg for Intact versus 5.9 +/- 3.68 mm Hg for allograft; p less than 0.001) and for exercise mean pressure gradient (27.8 +/- 8.63 mm Hg versus 8.1 +/- 8.43 mm Hg; p less than 0.001). The differences between the valve areas at rest also were significant (1.1 +/- 0.12 cm2 versus 2.2 +/- 0.62 cm2; p less than 0.01). It is concluded that when a tissue valve is indicated in patients with a small aortic root, the freehand allograft aortic valve is an ideal device from the hemodynamic perspective and is superior to the Intact valve. It is also probably superior in this respect to the St. Jude Medical valve, although the analysis may be biased slightly in favor of the allograft valve.     

Regurgitant flow field characteristics of the St. Jude bileaflet mechanical heart valve under physiologic pulsatile flow using particle image velocimetry

The regurgitant flow fields of clinically used mechanical heart valves have been traditionally studied in vitro using flow visualization, ultrasound techniques, and laser Doppler velocimetry under steady and pulsatile flow. Detailed investigation of the forward and regurgitant flow fields of these valves can elucidate a valve's propensity for blood element damage, thrombus formation, or cavitation. Advances in particle image velocimetry (PIV) have allowed its use in the study of the flow fields of prosthetic valves. Unlike other flow field diagnostic systems, recent work using PIV has been able to relate particular regurgitant flow field characteristics of the Bjork-Shiley Monostrut valve to a propensity for cavitation. In this study, the regurgitant flow field of the St. Jude Medical bileaflet mechanical heart valve was assessed using PIV under physiologic pulsatile flow conditions. Data collected at selected time points prior to and after valve closure demonstrated the typical regurgitant jet flow patterns associated with the St. Jude valve, and indicated the formation of a strong regurgitant jet, in the B-datum plane, along with twin vortices near the leaflets. Estimated ensemble-average viscous shear rates suggested little potential for hemolysis when the hinge jets collided. However, the vortex motion near the occluder tips potentially provides a low-pressure environment for cavitation.     

Tricuspid valve replacement with the St. Jude Medical valve: 19 years of experience.

OBJECTIVE: The choice of the valve substitute in the tricuspid position remains controversial. A St. Jude Medical valve is a choice of valve substitute and its lower thrombogenicity and excellent hemodynamic performance have been reported even in the tricuspid position. However, little is known of the long-term durability of the St. Jude Medical valve in the tricuspid position. Our long-term experience of tricuspid valve replacement showed the higher thrombogenicity than we had expected, therefore, this study was done to reconsider our strategy for valve choice. METHODS: This study reviewed 23 patient who underwent 25 tricuspid valve replacements with the St. Jude Medical valves from 1980 to 1997. The mean age was 40 years. Eleven patients (48%) were men. There were four in-hospital deaths (17%). The remaining 19 patients were all alive and followed from 2.2 to 19.0 years (mean 11.8 years). RESULTS: The overall survival, including hospital mortality, was 83%, 10 and 15 years after surgery. Valve thrombosis occurred in six patients. Freedom from valve thrombosis was 78 and 70%, 10 and 15 years after surgery, respectively. The linearized rate of the valve thrombosis was 2.9%/patient-years. Six patients required reoperation. The mean interval to reoperation was 9.5 years. Freedom from reoperation was 83% and 75%, 10 and 15 years after surgery, respectively. The linearized rate of the reoperation was 2.8%/patient-years. No structural valve deterioration was found. Echocardiographic study showed that the function of the St. Jude Medical valve without valve-related complications was well maintained. CONCLUSIONS: The higher thrombogenicity of the St. Jude Medical valve in the tricuspid position altered our choice of valve substitutes from the St. Jude Medical valve to a bioprosthesis which is lack of need for anticoagulant therapy except for juvenile patients who are able to maintain potent anticoagulant therapy.     

Tubular heart valves: a new tissue prosthesis design--preclinical evaluation of the 3F aortic bioprosthesis

BACKGROUND: It was hypothesized that native heart valves function as if they were simple tubes with sides that collapse when external pressure is applied. Because "form follows function," this hypothesis could theoretically be confirmed by implanting a simple tube into the anatomic position of any native heart valve and documenting that under the same anatomic constraints and physiologic conditions as the native valve, the tube would assume the form of that native valve. If the hypothesis were thus proved, it would follow that a tissue valve based on a tubular design would have superior flow dynamics and stress distribution and would therefore be expected to outlast currently available tissue valves. Such a tubular tissue valve, the 3F Aortic Bioprosthesis (3F Therapeutics, Inc, Lake Forest, Calif) was designed and tested in vitro against a commercially available stentless aortic bioprosthesis. METHODS: With the use of state-of-the-art testing equipment, some of which had to be developed especially to test this truly stentless bioprosthesis in vitro, transvalvular gradients, effective orifice areas, degree of transvalvular laminar flow, finite element analysis of the distribution of leaflet stress, and accelerated wear testing for long-term durability were evaluated for the new 3F Aortic Bioprosthesis in comparison with the St Jude Medical Toronto SPV aortic bioprosthesis (St Jude Medical, Inc, St Paul, Minn). RESULTS: The valve gradients were lower and the effective orifice areas were greater for the 3F Aortic Bioprosthesis at all valve sizes and under all test conditions, including cardiac outputs ranging from 2.0 to 7.0 L/min, mean perfusion pressures from 40 to 200 mm Hg, and aortic compliances of 4% and 16%. The transvalvular flow across the 3F Aortic Bioprosthesis in vitro was qualitatively smooth, with a minimum of surrounding vortices. Maximum stress occurred in the belly of the leaflets of the 3F Aortic Bioprosthesis, with minimum stress at the commissural posts. The 3F Aortic Bioprosthesis was superior to the Toronto SPV valve in accelerated wear tests. CONCLUSIONS: These in vitro studies show that a tissue aortic valve designed on the basis of the proved engineering principle that form follows function has better hemodynamics, flow dynamics, stress distribution, and durability when compared under identical in vitro conditions with an excellent commercially available tissue aortic valve.     

The choice of anticoagulation in pediatric patients with the St. Jude Medical valve prostheses

Between February 1982 and January 1984 27 St. Jude Medical cardiac valve prostheses were implanted in 24 children ranging in age from 5 to 20 years (mean 12.38 years). There were 10 isolated aortic valve replacements, 14 isolated mitral valve replacements and one triple valve replacement (aortic, mitral and tricuspid). There was one operative and four late deaths. All patients were maintained on Aspirin and Dipyridamole from the early postoperative period. There were six documented thromboembolic events occurring in five patients. There were 0.68 thromboembolic events per patient year in the aortic valve group and 0.19 events in the mitral valve group. Because of the significant incidence of thromboembolic events in our patients, we now recommend universal anticoagulation with Coumadin in all pediatric age patients in whom the St. Jude Medical prosthesis is implanted.     

Hydrodynamic Investigation of Mechanical Bileaflet Valves

For hydrodynamic comparison, 11 mechanical bileaflet valves have been perfused in a mock circulation system under pulsatile flow conditions. Six St. Jude Medical valves with different sizes from No. 21 to No. 31 and five Duromedics prostheses with corresponding sizes from No. 21 to No. 29 have been investigated. Flow, pressure, and orifice area were measured, while cardiac output was varied between 2 and 6 L/min. Insufficiency (I), maximal orifice area (Amax), mean orifice area (A), discharge coefficient (CD), performance index (PI), and efficiency index (EI) were determined. The St. Jude Medical valves show higher values of orifice area when compared with the Duromedics valves. For smaller valve sizes up to No. 25, the values of the orifice area are similar. The Duromedics valves show much lower values of insufficiency; thus, for small valve sizes, the Duromedics prosthesis seems to be superior. For larger valve sizes (No. 27, No. 29, and No. 31), a decision has to be made whether higher insufficiency and higher orifice area of the St. Jude Medical valve or lower insufficiency with lower orifice area is more acceptable.     

Clinical outcome in patients with 19-mm and 21-mm St. Jude aortic prostheses: comparison at long-term follow-up

BACKGROUND: Small-sized prostheses for aortic valve replacement may result in residual left ventricular outflow tract obstruction. Aim of the study was to verify whether implantation of 19-mm versus 21-mm St. Jude Medical standard prostheses (St. Jude Medical, Inc, St. Paul, MN) influences long-term clinical outcome. METHODS: Two hundred twenty-nine patients who underwent aortic valve replacement with 19 mm (group 1, 53 patients) or 21-mm St. Jude Medical standard prostheses (group 2, 176 patients) were included in the study. Mean follow-up of current survivors was 10+/-4 years. RESULTS: Operative mortality was 7.5% in group 1 and 8.5% in group 2. At discharge, an important patient-prosthesis mismatch (effective orifice area index < or = 0.60 cm2/m2) was present in 18% of group 1 versus 5% in group 2 (p = 0.004). Among patients with body surface area less than 1.70 m2, such mismatch was present in 15% of group 1 versus 2% of group 2 (p = 0.008). At last follow-up New York Heart Association (NYHA) functional class (p < 0.001), left ventricular mass reduction (p = 0.02), mean (p = 0.002) and peak transprosthetic gradients (p < 0.001), and effective orifice area index (p = 0.005) were significantly better in group 2. Freedom from sudden death (92%+/-5% vs 99%+/-1%, p = 0.01), valve-related death (84%+/-6% vs 90%+/-5%, p = 0.02), and cardiac events (56%+/-13% vs 86%+/-4%, p = 0.008), were significantly lower in group 1. Effective orifice area index was an independent predictor of late cardiac events. CONCLUSIONS: Although long-term results after aortic valve replacement with small-sized St. Jude Medical standard prostheses are satisfactory, 19-mm valve recipients show a high prevalence of important patient-prosthesis mismatch with less evident functional improvement and higher rate of cardiac events, suggesting a very cautious use of this prosthesis.