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.     

Comparative Rest and Exercise Hemodynamics of Allograft and Prosthetic Valves in the Aortic Position

Background. Allograft aortic valve replacement has gained widespread acceptance. However, there is little information about in vivo allograft valve function at rest and during exercise.

Methods. Cardiac catheterization was performed to measure hemodynamic variables at rest and during supine bicycle exercise in 44 patients who had had aortic valve replacement using allograft valves or Bicer or St. Jude Medical prosthetic valves 19 to 27 mm in diameter. Sixteen patients received an allograft valve; 17, a Bicer valve; and 11, a St. Jude Medical valve. There were no significant differences between the three groups in age, body surface area, left ventricular end-systolic and end-diastolic volume indices, exercise cardiac index, exercise heart rate, or work load achieved. Left ventricular and ascending aortic pressures were measured simultaneously according to the transseptal method.

Results. The mean pressure gradient was generally higher for the Bicer and St. Jude Medical valves than for the allograft valves, both at rest and during exercise. Significant differences were obtained in patients with small-sized valves (21 and 23 mm); pressure gradients were higher in the prosthetic valve groups. In patients with large-sized prosthetic valves (25 mm), there were no significant differences between the three groups at rest and during exercise. However, there was no pressure gradient at all for allograft valves.

Conclusions. Exercise cardiac catheterization confirms that the allograft aortic valve is an ideal substitute from the hemodynamic aspect, particularly in patients with a small aortic root and in those who perform strenuous exercise.     

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.     

In vitro hemodynamic characteristics of prosthetic heart valves

The functional characteristics of the prosthetic heart valve are the hemodynamic characteristics when it has been ideally attached; in clinical practice, however, it is seldom that this artificial valve is ideally put in position because of the modality of changeable valve angle in deformed annulus and the narrow aortic root, orientation of the valve, anatomical factors, etc. Thus, we devised an attachment head for the prosthetic valve whose angle can freely be varied in order to evaluate the hemodynamic characteristics of five clinically-available mechanical prosthetic valves and two xenografts in the pulsatile circulation system in the mitral position by changing the angle and orientation of the valve attachment. The prosthetic valves used were St Jude Medical (SJM), Starr-Edwards ball (S-E), monostrut Bj?rk-Shiley (mB-S), Omniscience (OS), Omnicarbon (OC), Carpentier-Edwards Supra-annular (C-Es) and Carpentier Edwards Pericardial (C-Ep) whose tissue annulus diameter was 27 mm. The experimental instrument similar to that of Umezu et al. was prepared to determine the mean pressure gradient, output and calculated orifice area of each valve. At the same time, a recently-manufactured valve attachment head was employed to measure the output, pressure gradient and orifice area by altering the valve attachment angle and orientation and increasing the number of heart beats from 60 bpm to 160 bpm, and the following results were obtained: With the changeable angle valve, an angle was determined whose end was parallel to the flow path in association with changes in the attachment angle, and the orientation was such that the pressure gradient was reduced and the orifice area was increased.(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical evaluation of ATS prosthetic valve by doppler echocardiography: comparison with St. Jude Medical (SJM) valve.

ATS valve is a bileaflet valve developed to have a superior function to traditional prosthetic valves on anti-thrombogenesis and hemolysis. The orifice area was enlarged in consequence of making its orifice with pyrolytic carbon materials, and the pivot was open pivot and the strut was eliminated. The efficiency of this valve has been reported in the Europe. In Japan, its clinical trial was performed in September 1993 and its clinical use was permitted in August 1996. In this study, we compared the functions of ATS and St. Jude Medical (SJM) valves with echocardiography. The pressure gradients at the mitral valve position were not significantly different between ATS and SJM valves, but that of ATS was lower than that of SJM. The pressure gradient at the aortic valve position of ATS was also lower than that of SJM, and especially those of the patients who performed aortic valve replacement with 23-mm ATS and SJM valves were 8.9+/-1.6 and 23.3+/-6.6 mmHg, showing a significant difference. Though further observation and review of this valve are needed at the chronic phase, ATS valve is an excellent bileaflet valve on the valvular function, showing a low pressure gradient.     

Hemodynamic evaluation of the prosthetic heart valves implanted in the aortic position

In order to solve the problems of "valve-patient mismatch", hemodynamic problems with prosthetic heart valves implanted in the aortic position, and to clarify suitable size of the prostheses, in vivo hemodynamic studies and studies on the postoperative reduction of left ventricular (LV) hypertrophy were performed in 68 aortic valve replacement patients with various types of prosthetic valves. The pressure gradient across the valve (LV-Ao PG) and effective orifice area (EOA) were measured by perioperative pressure study and by continuous-wave Doppler echocardiography during the postoperative period. The postoperative reduction of LV hypertrophy was evaluated from the reductions of LV mass volume (LVM) on the M-mode echocardiogram, cross sectional area (CSA) on the two-dimensional echocardiogram, CTR on chest X-ray film and SV1 + RV5 on the electrocardiogram. A linear relationship was observed between cardiac output (CO) and LV-Ao PG in each type of prosthetic valve, and the slope of their correlation equation, showing the rate of increase in LV-Ao PG with the increase in CO, was steeper in the prosthesis with a smaller orifice area. The mean value of EOA-echo was 1.4 cm2 in the 19 mm St. Jude Medical valve, 1.6 cm2 in 21 mm Bj?rk-Shiley (BS), 1.9 cm2 in 23 mm BS, 1.7 cm2 in 21 mm Medtronic Hall (MH) and 2.1 cm2 in 23 mm MH.(ABSTRACT TRUNCATED AT 250 WORDS)     

In vitro hydrodynamic characteristics of heart valves in tricuspid position

At present there are many problems concerning the choice of heart valve for cardiac valve replacement in the tricuspid position. Thus, we devised an attachment head for the prosthetic valve in order to evaluate the hemodynamic characteristics of four clinically-available mechanical prosthetic valves and two xenografts in the pulsatile circulation system in the tricuspid position. Six artificial cardiac valves were used in this experiment; St. Jude Medical (SJM), Starr Edwards ball (S-E), monostrut Bj?rk Shiley (B-S), Omnicarbon, Carpentier Edwards (CE) supraannular, CE-pericardial whose tissue annulus diameter was 27 mm. The experimental instrument similar to that of Umezu et al, was prepared to determine the mean pressure gradient, output and calculated orifice area of each valve. Since many of the patients who must undergo tricuspid valve replacement have severe multi valvular diseases with atrial fibrillation, we experimented also under the condition of atrial fibrillation. At sinus rhythm under pulsation flow, no significant difference was shown in cardiac output between the various valves, but pressure gradient was higher with xenografts than with mechanical prostheses, and the SJM valve showed the widest efficient valve orifice area. The reduction rate of the efficient valve orifice area from sinus rhythm to atrial fibrillation was about 10% in the SJM valve, which was better rate than other heart valves. We observed significant differences in cardiac output, pressure gradient and efficient orifice area at sinus and atrial fibrillation rhythm. (p less than 0.01).     

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.     

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.     

Valve replacement in the right side of the heart in children: long-term follow-up

Twenty-five patients (16 male, 9 female) underwent right-sided valve replacement (10 pulmonary valve replacement, 14 tricuspid valve replacement, 3 tricuspid plus pulmonary valve replacement, and 2 replacements of a single atrioventricular valve) at the University of Nebraska Medical Center from June 1977 to December 1986. Twenty-one patients (84%) are long-term survivors with 2,035 months follow-up (range, 41 to 143 months; mean, 96.9 months). Twenty-three Carpentier-Edwards bioprosthetic valves, one Ionescu-Shiley bioprosthetic valve, and nine St. Jude Medical valves were inserted. Follow-up of 17 patients with a Carpentier-Edwards valve ranged from 5 years 9 months to 11 years 9 months (mean, 8 years 11 months). To date there has been one reoperation after 3 years 4 months in this group. One patient who received an Ionescu-Shiley bioprosthesis required re-replacement at 20 months after operation. Three of 4 patients who received St. Jude mechanical valves and are long-term survivors have required replacement after 36 to 56 months. We conclude that the Carpentier-Edwards bioprosthetic valve is a viable option in the right side of the heart in the young age group when annular size is adequate to accommodate an appropriate bioprosthesis.     

Twenty-year comparison of tissue and mechanical valve replacement

OBJECTIVE: We sought to compare outcomes with tissue and St Jude Medical mechanical valves over a 20-year period. METHODS: Valve-related events and overall survival were analyzed in 2533 patients 18 years of age or older undergoing initial aortic, mitral, or combined aortic and mitral (double) valve replacement with a tissue valve (Hancock, Carpentier-Edwards porcine, or Carpentier-Edwards pericardial) or a St Jude Medical mechanical valve. Total follow-up was 13,390 patient-years. There were 666 St Jude Medical aortic valve replacements, 723 tissue aortic valve replacements, 513 St Jude Medical mitral valve replacements, 402 tissue mitral valve replacements, 161 St Jude Medical double valve replacements, and 68 tissue double valve replacements. The mean age was 68 +/- 13.3 years (St Jude Medical valve, 64.5 +/- 12.9; tissue valve, 72.0 +/- 12.6). RESULTS: There were no overall differences in survival between tissue and mechanical valves. Multivariable analysis indicated that the type of valve did not affect survival. Analysis by age less than 65 years or 65 years or older and presence or absence of coronary disease revealed similar long-term survival in all subgroups. The risk of hemorrhage was lower in patients receiving tissue aortic valve replacements but was not significantly different in patients receiving mitral valve or double valve replacements. Thromboembolism rates were similar for tissue and mechanical valve recipients. However, reoperation rates were significantly higher in patients receiving both aortic and mitral tissue valves. The reoperation hazard increased progressively with time both in patients receiving aortic and in those receiving mitral tissue valves. Overall valve complications were initially higher with mechanical aortic valves but not with mechanical mitral valves. However, valve complication rates later crossed over, with higher rates in tissue valve recipients after 7 years in patients undergoing mitral valve replacement and 10 years in those undergoing aortic valve replacement. CONCLUSIONS: Tissue and mechanical valve recipients have similar survival over 20 years of follow-up. The primary tradeoff is an increased risk of hemorrhage in patients receiving mechanical aortic valve replacements and an increased risk of late reoperation in all patients receiving tissue valve replacements. The risk of tissue valve reoperation increases progressively with time.     

Clinical evaluation of St Jude Medical Hemodynamic Plus versus standard aortic valve prostheses: The Italian multicenter, prospective, randomized study

OBJECTIVE: Hemodynamic and clinical performances of 21-mm and 23-mm St Jude Medical Hemodynamic Plus aortic valves (St Jude Medical, Inc, St Paul, Minn) were compared with those of 21-mm and 23-mm St Jude Medical standard cuff aortic valves in the first such multicenter, prospective, randomized study. Hemodynamic Plus valves are mechanical, bileaflet prostheses suitable for the small aortic anulus. METHODS: Patients with 21-mm and 23-mm anulus diameters were randomized to receive either a Hemodynamic Plus or a standard cuff valve. Postoperatively and at 6 months after the operation, patients underwent 2-dimensional Doppler echocardiography. Ejection fraction, cardiac output, peak gradient, mean gradient, effective orifice area, effective area index, and performance index were calculated. Postoperative and 6-month echocardiographic measurements and their variations across observation times were analyzed statistically. RESULTS: Of the 140 patients enrolled, 5 died at operation and 1 died of aortic dissection during the follow-up period. Eight patients were lost to follow-up. A total of 125 patients completed the study. In 1 patient a sewing cuff escaped intraoperatively. At 6 months the 21-mm and 23-mm Hemodynamic Plus valves showed significantly lower peak gradients and mean gradients than those of the 21-mm and 23-mm standard cuff valves. The 21-mm Hemodynamic Plus valves had gradients similar to those of the 23-mm Hemodynamic Plus valves. The effective orifice area did not differ significantly between the Hemodynamic Plus and standard cuff valves at either measurement. No valve mismatch was found in the 4 groups of patients. A more enhanced decrease of peak gradients and mean gradients and a more enhanced increase of effective orifice areas, effective area indices, and performance indices were found across observation times for patients with Hemodynamic Plus valves compared with those with standard cuff valves. CONCLUSIONS: Clinical hemodynamic performances of 21-mm and 23-mm St Jude Medical Hemodynamic Plus valves correspond closely with those of standard cuff valves, and gradients are substantially better than those of standard cuff valves of the same diameter. Therefore, use of this valve may minimize the need for aortic anulus enlargement. Early follow-up results with the Hemodynamic Plus valves were excellent, although more time is required to confirm this outcome.     

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.     

Obstruction of St Jude Medical valves in the aortic position: significance of a combination of cineradiography and echocardiography

BACKGROUND: Obstruction of the St Jude Medical valve (St Jude Medical, Inc, St Paul, Minn) is a rare but serious complication. METHODS: Cineradiographic and echocardiographic evaluations of aortic St Jude Medical valves were simultaneously performed on 54 patients, with no signs of prosthetic valve dysfunction late after surgery. RESULTS: Although closing angles of the leaflets corresponded closely with the manufacturer data, restricted opening of the leaflets (opening angle >/= 20 degrees ) was found in 16 (group D) of the 54 patients by means of cineradiography. The opening angles were equal to or less than 14 degrees in the other 23 patients (group N) and between 15 degrees and 19 degrees in the remaining 15 (group M). Doppler-derived transprosthetic pressure gradients were significantly higher (P =.03) and the velocity index was significantly lower (P =.003) in group D than in group N. However, no significant differences were found in those values between group N and group M. Replacement of the aortic St Jude Medical valves was performed in 5 of the 16 patients, and the remaining 11 have been followed up because of relatively low pressure gradients. The cause of restricted leaflet movement was pannus formation without thrombosis in 4 patients and valve thrombosis with pannus formation in one. CONCLUSIONS: Reduced valve orifice area and restricted opening of the leaflets resulting from excess growth of pannus probably led to obstruction of the aortic St Jude Medical valves. A combination of cineradiography and echocardiography makes it possible to provide an accurate and detailed diagnosis of obstruction of the valve.     

Thrombosis of two St. Jude Medical prostheses in one patient after triple valve replacement. Case report and review of the literature

Reports of experience with the St. Jude Medical (SJM) valve state that thrombosis of the prosthesis is a rare complication. In a 57-year-old woman, reoperation was necessary 12 months after triple valve replacement using SJM prostheses because of thrombosis of the valves in the tricuspid and aortic positions. Dysfunction of both mechanical valves was detected clinically by changing heart sounds and the appearance of murmurs. Echocardiography and cinefluoroscopy confirmed at least one fixed leaflet of the tricuspid prosthesis, but abnormalities of the aortic prosthesis could not be detected. At reoperation, the SJM prosthesis in the tricuspid position was almost completely thrombosed and was replaced by an Ionescu-Shiley bioprosthesis. A thrombotic formation at the hinge point of the SJM aortic prosthesis was removed. To our knowledge, this is the first report of a thrombotic complication of two SJM prostheses after triple valve replacement in one patient.     

In vitro evaluation of hydrodynamics of prosthetic heart valves

The hydrodynamics of various prosthetic heart valves currently available commercially were studied in our mock circulation system by analysis of flow-pressure gradient and opening angle. Using the circulation system, various prosthetic heart valves were tested in the simulative states of normal hemodynamics, low output, arrhythmia, hypovolemia, and vasoconstriction. The flow-pressure gradient analysis demonstrated the characteristics of each valves clearly. The St. Jude Medical valve showed the superior valve characteristics over other mechanical valves. The opening angles of the tilting disc prosthetic valves were also studied in the same simulative circulation using the photosensor system with real-time monitoring. In contrast to our clinical experiences of poor opening of Omniscience valve in the mitral position, limitation of the opening angle of the valve was not observed in this in vitro study.     

New approach for replacement of degenerated mitral bioprostheses

OBJECTIVE: The most common indication for reoperation in patients with a mitral bioprosthetic valve is primary tissue failure. Explanation of the bioprosthesis is time-consuming and may be complicated by cardiac rupture at the atrioventricular junction or the posterior left ventricular wall where a strut is imbedded, injury to the circumflex artery and late perivalvular leak. A new approach to avoid these complications by excising only the bioprosthetic tissue and attaching a reversed aortic St. Jude valve to the intact stent has been developed and evaluated. METHODS: We have replaced degenerated mitral bioprostheses with a St. Jude valve in 73 patients during the last 12 years. In 57, including all who had their operation before 1991, explantation was used. The stent was preserved in 16 patients; in the first four we implanted a mitral St. Jude valve (SJM) within the stent, but this only allows a SJM 6-8 mm smaller than the bioprosthesis. We evolved our approach in the last 12 patients to suture a reversed aortic St. Jude valve with extended cuff to the atrial side of the bioprosthetic cuff; this allows the use of a St. Jude valve 2 mm smaller than the bioprosthesis with exact matching of the orifice sizes. The demographic and clinical profiles of the two groups were similar. RESULTS: Operative mortality was 8/57 (14%) in the explantation group and none in the stent-preservation group. Three late perivalvular leaks occurred in the explanation group, and none in the stent-preservation group. Thirteen late deaths occurred in the explanation group, with a 5-year survival rate of 68%, and one late death (cancer) in the stent-preservation group, but the follow-up is significantly shorter. CONCLUSIONS: Leaving the mitral bioprosthetic stent and cuff intact eliminates the need for extensive dissection, thus shortening and simplifying the procedure and diminishing its attendant mortality and morbidity. It offers a safe and logical approach to replacement of a degenerated mitral bioprosthesis with a St. Jude valve of comparable size which projects into the left atrium, rather than a smaller one jammed into the orifice of the bioprosthetic stent.     

Late results after mitral valve replacement with bileaflet mechanical prosthesis in children: evaluation of prosthesis-patient mismatch

BACKGROUND: Mechanical prosthesis is the choice of valve at the mitral position in children, although re-replacement of prostheses because of prosthesis-patient mismatch is almost inevitable when prostheses were implanted in small children. The methods to predict prosthesis-patient mismatch as a result of patients' somatic growth or pannus formation in children by noninvasive methods have not been well established. METHODS: Thirty-two children underwent mitral valve replacement with 37 bileaflet mechanical prostheses (26 St. Jude Medical prosthetic valves, and 11 CarboMedics prosthetic valves) and were followed up a mean of 6.8 years (maximum 18.3 years) with a complete follow-up rate of 94%. RESULTS: There were no operative deaths and 5 late deaths. Re-replacement of mitral valve because of prosthesis-patient mismatch was required in 5 patients. Freedom from valve-related events and re-replacement of mitral valve at 15 years were 32% +/- 23% and 54% +/- 18%, respectively. Actuarial survival rate was 63% +/- 19% at 15 years. Prosthetic valve orifice area index (manufactured geometric prosthetic valve area divided by patient's body surface area) was well correlated with maximum transprosthesis flow velocity estimated by Doppler echocardiography during follow-up, whereas valve orifice area index had no significant correlation with pulmonary artery wedge pressure assessed by cardiac catheterization. Maximum transprosthesis flow velocity had a significant correlation with pulmonary artery wedge pressure. CONCLUSIONS: Valve orifice area index itself was not a reliable index to predict prosthesis-patient mismatch. Maximum transprosthesis flow velocity was a useful index to predict pulmonary artery wedge. Invasive cardiac catheterization to determine re-replacement of the prosthesis should be considered when maximum transprosthesis flow velocity exceeds 270 cm/s.     

Comparative study of the hydrodynamic function of the CarboMedics valve

The hydrodynamic function of each size of the CarboMedics valve was assessed in a pulsatile flow simulator. The mean pressure difference with respect to forward flow, regurgitant volumes, and total energy loss across each valve were analyzed. The results for the 23-mm aortic and 29-mm mitral CarboMedics valves were compared with those for the St. Jude Medical and Bj?rk-Shiley Monostrut valves. Results showed good hydrodynamic function for each CarboMedics valve, although the pressure difference and total energy loss across the 19-mm aortic valve was high. The hydrodynamic function of the CarboMedics valve was comparable with that of the St. Jude Medical valve. Both valves showed similar leakage volumes, which were significantly larger than that for the Bj?rk-Shiley Monostrut valve. On account of this the total energy loss in the Bj?rk-Shiley valve was significantly less than that for the bileaflet valves in the aortic position. Concern remains for the continuing presence of high closed-valve regurgitation in the bileaflet valves.     

Left ventricular outflow tract obstruction with mitral valve replacement in small ventricular cavities

The inference that mitral valve replacement (MVR) may produce left ventricular outflow tract (LVOT) obstruction has been made, but no comparative hemodynamic studies with various types of prostheses have been done. The purpose of the present study was to compare the gradients created across the LVOT with MVR in young sheep with small left ventricular cavities. Mitral valve replacement was accomplished using cardiopulmonary bypass and hypothermic cardioplegic arrest. Five animals were used for each of the following valves studied: 25-mm Ionescu-Shiley bovine pericardial valve, 25-mm Hancock porcine aortic valve, 2M-6120 28-mm Starr-Edwards ball-valve prosthesis, 25-mm Bj?rk-Shiley 60-degree flat tilting-disc prosthesis, and 25-mm St. Jude Medical hemidisc valve. Gradients across the LVOT were measured after MVR and then during infusion of isoproterenol hydrochloride (0.05 micrograms/kg/min). Following MVR, only the Starr-Edwards valve produced an LVOT gradient (32 +/- 23 mm Hg). Substantial gradients after MVR were seen, however, with isoproterenol administration with the Ionescu-Shiley (47 +/- 4 mm Hg), Hancock (13 +/- 8 mm Hg), and Starr-Edwards (65 +/- 30 mm Hg) valves but not with the low-profile valves (Bj?rk-Shiley and St. Jude Medical). The results of the present study demonstrate that MVR can produce LVOT obstruction. The greatest degree of obstruction was with the high-profile mechanical and bioprosthetic valves.