Hemolysis after mitral valve replacement with mechanical valve prostheses

OBJECTIVE: We evaluated effects of type, size, and orientation of mechanical mitral valve prostheses on hemolysis. METHODS: Subjects were 84 patients who had undergone mitral valve replacement. Lactate dehydrogenase was mainly used as a marker of hemolysis and was measured before surgery, 1 month after surgery, and in the late postoperative period. RESULTS: Valves used included 16 Medtronic-Hall, 32 St. Jude Medical, and 36 CarboMedics valves. Medtronic-Hall valves caused less hemolysis than St. Jude Medical or CarboMedics valves in the late postoperative period. This resulted because hemolysis due to Medtronic-Hall valves was more severe 1 month after surgery than in the late postoperative period and because hemolysis due to St. Jude Medical or CarboMedics valves was more severe in the late postoperative period than 1 month after surgery. One reason for this finding is that cardiac output was greater in the late postoperative period than 1 month after surgery, making regurgitation through the pivots of bileaflet valves more severe. The orifice area and the orientation of prostheses did not affect hemolysis. CONCLUSION: St. Jude Medical or CarboMedics valves caused more severe hemolysis than Medtronic-Hall valves in the late postoperative period.     

Comparison of survival after mitral valve replacement with biologic and mechanical valves in 1139 patients

OBJECTIVE: We sought to compare 10-year survival in patients after mitral valve replacement with biologic or mechanical valve prostheses. METHODS: Retrospective survival analysis was performed on data from 1139 consecutive patients older than 18 years of age undergoing mitral valve replacement with Carpentier-Edwards (n = 495; Baxter Healthcare Corp, Irvine, Calif) or St Jude Medical (n = 644; St Jude Medical, Inc, St Paul, Minn) prostheses. RESULTS: The 10-year survival was not statistically different between the patients receiving Carpentier-Edwards valves and those receiving St Jude Medical valves (P =.16). Adjusted survival estimates at 2, 5, and 10 years were 82% +/- 2% (95% confidence intervals, 79%-85%), 69% +/- 2% (95% confidence intervals, 64%-73%), and 42% +/- 3% (95% confidence intervals, 37%-48%), respectively, for the Carpentier-Edwards group and 83% +/- 2% (95% confidence intervals, 80%-86%), 72% +/- 2% (95% confidence intervals, 69%-76%), and 51% +/- 3% (95% confidence intervals, 45%-58%), respectively, for the St Jude Medical group. Predictors of worse survival after mitral valve replacement are older age, lower ejection fraction, presence of class IV congestive heart failure, coronary artery disease, renal disease, smoking history, hypertension, concurrent other valve surgery, and redo heart surgery. CONCLUSION: Choice of biologic or mechanical prosthesis does not significantly affect long-term patient survival after mitral valve replacement.     

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.     

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.     

Intravascular hemolysis in patients with new-generation prosthetic heart valves: a prospective study

OBJECTIVE: A prospective clinical study was designed to assess the frequency and severity of intravascular hemolysis in patients with new-generation, normally functioning prosthetic heart valves. METHODS: Hemolysis was evaluated in 172 patients with a mechanical prosthesis (53 CarboMedics and 119 Sorin Bicarbon) and in 106 patients with a bioprosthesis (15 St Jude Medical Toronto, 19 Baxter Perimount, and 72 Medtronic Mosaic) in the aortic position, mitral position, or both. Aortic valve replacement was performed in 206 patients, mitral valve replacement in 59 patients, and double valve replacement in 13 patients. The presence of hemolysis was assessed on the basis of the level of serum lactic dehydrogenase and serum haptoglobin and the presence and amount of reticulocytes and schistocytes in the peripheral blood. Severity of intravascular hemolysis was estimated on the basis of serum lactic dehydrogenase. Clinical, echocardiographic, and hematologic evaluations were performed 1, 6, and 12 months after discharge. RESULTS: None of the 278 patients experienced decompensated anemia, whereas at 12 months, mild subclinical hemolysis was identified in 49 patients, 44 (26%) with a mechanical prosthesis and 5 (5%) with a bioprosthesis (P <.001). At multivariate analysis, independent predictors of the presence of subclinical hemolysis were mitral valve replacement (P <.001), use of a mechanical prosthesis (P =.002), and double valve replacement (P =.02). Frequency of hemolysis in patients with stented aortic bioprostheses was 3%, whereas it was absent in those with stentless valves. Among mechanical valve recipients, double versus single valve replacement (P =.04) and mitral versus aortic valve replacement (P =.05) were correlated with the presence of hemolysis; double valve recipients also showed a more severe degree of hemolysis (P =.03). In patients with a Sorin Bicarbon prosthesis, hemolysis was less frequent (22% vs 34%, P =.09) and severe (P <.001) than in those with a CarboMedics prosthesis. CONCLUSIONS: In normally functioning prosthetic heart valves, subclinical hemolysis is a frequent finding. A low incidence of hemolysis is found in stented biologic prostheses, and it is absent in stentless aortic valves. Modifications of valve design may contribute to minimize the occurrence of hemolysis in mechanical prostheses.     

In vitro investigation of opening behavior and hydrodynamics of bileaflet valves in the mitral position

The performance of four 25 mm bileaflet valves of different designs was evaluated in the mitral position of our own pulse simulator. With the aid of a high-speed video camera, it was demonstrated that both the St. Jude Medical (SJM) valve (Hemodynamic Plus [HP] Series, St. Jude Medical, Inc., St. Paul, MN, U.S.A.) and the CM valve (CarboMedics, Inc., Austin, TX, U.S.A.) were able to open fully and that the CM valve fluttered much more vigorously at the fully open position than did the SJM HP valve. Conversely, neither the ATS valve (ATS Medical, Inc., Minneapolis, MN, U.S.A.) nor the On-X valve (Medical Carbon Research Institute, Austin, TX, U.S.A.) exhibited movement to a fully open configuration. The overall average opening angles of the ATS and the On-X, on 3, 4, and 5 L/min flow rate for a heart rate of 70 bpm and 5, 6, and 7 L/min for 100 bpm, were 74.8 degrees and 81.6 degrees, respectively, whereas their design opening angles were 85 degrees and 90 degrees. Pressure drops across the CM and the ATS were consistently higher than those of the On-X and the SJM HP. Closing volumes for all the valves were below 8% for a heart rate of 70 bpm. This in vitro investigation yielded the following conclusions: The ATS and On-X valves are not able to open fully in the mitral position, but this does not impair their normal function; both a larger orifice diameter and a large opening angle can decrease the pressure drop; in general, the On-X valve achieves its design goals in this experiment (i.e., it produces a lower pressure drop and lower closing volume by virtue of its large orifice and high-profile design); however, the hinge flow in the non-fully open state should be investigated further.     

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.     

Surgical treatment of the prosthetic valves in reoperation

Surgical treatment and problems in patients required reoperation for malfunctioning prosthetic valves are reviewed in our institute. The cinefluoroscopy and pulse doppler echocardiography were helpful for diagnosis of artificial valve dysfunction. In recent two decades valve replacement were performed in 382 cases and number of re-implanted valve were 469. Among them the cases of reoperation were 21 and reimplanted valves were 25 (5.6%); 4.7% in aortic, 5.0% in mitral, 6.7% in tricuspid position. Three cases of those patients had three operations. Main causes of reoperation were primary tissue failure in Carpentier-Edwards porcine xenograft (6 cases, 23%) and cloth wear in Starr-Edwards ball valve (9 cases, 38%) and thrombosis in St. Jude Medical bi-leaflet valve (3 cases, 15%). In most cases St. Jude Medical valve were chosen for the alternative prosthetic valve in reoperation. We applied IABP support to seven patients for severe low cardiac output syndrome after the operation and overall mortality was 24% in reoperation. It concluded that St. Jude Medical valve may be most reliable because of low incidence of postoperative complication in our institute.     

Intravascular hemolysis after prosthetic valve replacement

Two kinds of mechanical valve, St. Jude Medical (SJM) and Bj?rk-Shiley (B-S), in patients with single valve replacement have been evaluated on a view point of intravascular hemolysis. Cases were consisted of 78 SJM and 32 B-S for the mitral and 12 SJM and 36 B-S for the aortic positions. Serum LDH, indirect bilirubin, GOT, hemoglobin levels and reticulocyte count were pursued in a given schedule, especially on the 21st postoperative day. A follow-up study on cases with abnormally high level of LDH (over 800 W.U.) at the time of hospital discharge was also performed. Paravalvular leakage detectable on the echocardiographical study was denied in all cases. The case with SJM valve replacement on the mitral position revealed a higher level of LDH, GOT and a large count of reticulocyte than those in the B-S valve. Insignificantly was found, however, in the same study with replaced valve on the aortic position. There was no correlation between the severity of hemolysis and the size of prostheses. The level of LDH, remained in high on discharge declined gradually thereafter during postoperative observation. As a whole, the result of this study supports the conventional valve selection and usage in our clinic. The patient with subclinical hemolysis after valve replacement should be placed on a schedule of close observation.     

A retrospective comparative study of aortic valve replacement with St. Jude medical and medtronic-hall prostheses: a 20-year follow-up study

OBJECTIVE: To compare the long-term clinical outcome of patients who underwent aortic valve replacement with St. Jude Medical and Medtronic-Hall mechanical prostheses. DESIGN: From June 1978 to June 1982, 43 Medtronic-Hall and 48 St. Jude Medical mechanical valves were implanted in 90 consecutive patients with aortic valve disease, and their clinical outcome was retrospectively assessed. RESULTS: At 20 years in the St. Jude Medical group and in the Medtronic-Hall group the actuarial rates of overall survival were 50 and 49% (p = NS), of cardiovascular survival 66 and 63% (p = NS), of valve-related survival 95 and 91% (p = NS), of freedom from major valve-related complications 83 and 45% (p = 0.005), from major cerebrovascular events 93 and 71% (p =0.06), from valve thrombosis 97 and 89% (p = NS), from aortic valve reoperation 93 and 88% (p = NS), from major bleeding 96 and 82% (p = 0.04), and from endocarditis 93 and 82% (p = NS), respectively. The linearized rate of overall major aortic valve prosthesis-related complications was 3.47%/year in the Medtronic-Hall valve group and 1.53%/year in the St. Jude Medical valve group (p = 0.003). Multivariate analysis showed that the type of prosthesis was predictive of freedom from valve-related complications (p = 0.01; 2.849; C.I. 95%: 1.246-6.516). CONCLUSION: The aortic St. Jude Medical mechanical valve seems to be associated with a slightly lower rate of long-term valve-related morbidity than the aortic Medtronic-Hall mechanical valve. Because of the small patient population and the retrospective nature of the study, the choice between these two prostheses should not be made only on the basis of these findings. However, these results suggest a reappraisal for further comparative studies with such an extended follow-up.     

Baseline Platelet Aggregation and Major Receptor Expression Predict Subsequent Activity Following Thrombolysis for Acute Myocardial Infarction

Objective - To compare the long-term clinical outcome of patients who underwent aortic valve replacement with St. Jude Medical and Medtronic-Hall mechanical prostheses. Design - From June 1978 to June 1982, 43 Medtronic-Hall and 48 St. Jude Medical mechanical valves were implanted in 90 consecutive patients with aortic valve disease, and their clinical outcome was retrospectively assessed. Results - At 20 years in the St. Jude Medical group and in the Medtronic-Hall group the actuarial rates of overall survival were 50 and 49% ( p = NS), of cardiovascular survival 66 and 63% ( p = NS), of valve-related survival 95 and 91% ( p = NS), of freedom from major valve-related complications 83 and 45% ( p = 0.005), from major cerebrovascular events 93 and 71% ( p = 0.06), from valve thrombosis 97 and 89% ( p = NS), from aortic valve reoperation 93 and 88% ( p = NS), from major bleeding 96 and 82% ( p = 0.04), and from endocarditis 93 and 82% ( p = NS), respectively. The linearized rate of overall major aortic valve prosthesis-related complications was 3.47%/year in the Medtronic-Hall valve group and 1.53%/year in the St. Jude Medical valve group ( p = 0.003). Multivariate analysis showed that the type of prosthesis was predictive of freedom from valve-related complications ( p = 0.01; 2.849; C.I. 95%: 1.246-6.516). Conclusion - The aortic St. Jude Medical mechanical valve seems to be associated with a slightly lower rate of longterm valve-related morbidity than the aortic Medtronic-Hall mechanical valve. Because of the small patient population and the retrospective nature of the study, the choice between these two prostheses should not be made only on the basis of these findings. However, these results suggest a reappraisal for further comparative studies with such an extended follow-up.     

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.     

Long-term outcome after biologic versus mechanical aortic valve replacement in 841 patients

OBJECTIVE: The purpose of this study was to optimize selection criteria of biologic versus mechanical valve prostheses for aortic valve replacement. METHODS: Retrospective analysis was performed for 841 patients undergoing isolated, first-time aortic valve replacement with Carpentier-Edwards (n = 429) or St Jude Medical (n = 412) prostheses. RESULTS: Patients with Carpentier-Edwards and St Jude Medical valves had similar characteristics. Ten-year survival was similar in each group (Carpentier-Edwards 54% 3% versus St Jude Medical 50% 6%; P =.4). Independent predictors of worse survival were older age, renal or lung disease, ejection fraction less than 40%, diabetes, and coronary disease. Carpentier-Edwards versus St Jude Medical prostheses did not affect survival (P =.4). Independent predictors of aortic valve reoperation were younger age and Carpentier-Edwards prosthesis. The linearized rates of thromboembolism were similar, but the linearized rate of hemorrhage was lower with Carpentier-Edwards prostheses (P <.01). Perivalvular leak within 6 months of operation was more likely with St Jude Medical than with Carpentier-Edwards prostheses (P =.02). Estimated 10-year survival free from valve-related morbidity was better for the St Jude Medical valve in patients aged less than 65 years and was better for the Carpentier-Edwards valve in patients aged more than 65 years. Patients with renal disease, lung disease (in patients more than age 60 years), ejection fraction less than 40%, or coronary disease had a life expectancy of less than 10 years. CONCLUSIONS: For first-time, isolated aortic valve replacement, mechanical prostheses should be considered in patients under age 65 years with a life expectancy of at least 10 years. Bioprostheses should be considered in patients over age 65 years or with lung disease (in patients over age 60 years), renal disease, coronary disease, ejection fraction less than 40%, or a life expectancy less than 10 years.     

Experience with St. Jude Medical valve prosthesis in children. A word of caution regarding right-sided placement

Thirty-six children aged 6 months to 18 years, underwent insertion of 37 St. Jude Medical cardiac prostheses. In 20, the valve was placed in the aortic or mitral position, and in 16 in the pulmonary or tricuspid position. There was one (2.8%) hospital death. All patients received maintenance doses of salicylates and dipyridamole after the operation. Follow-up data are available for all patients for 12 to 24 postoperative months. There was no incidence of valve dysfunction or thromboembolic complication in any of the 20 patients with valves in the systemic (left) side of the circulation, and all manifested improvement in their functional class. In contrast, six (37%) of the 16 patients with valves in the pulmonary (right) side of the circulation developed dysfunction of the prosthesis 1 to 6 months after insertion. Prosthesis failure was associated with fibrous tissue growing into the struts, leading to leaflet immobilization. At 2 years, the actuarial functional life was 100% for mitral and aortic valves and 70% for pulmonary and tricuspid valves. The data illustrate the excellent hemodynamic function of the St. Jude Medical valve in children. The absence of thromboembolic complications warrant continued implantation of the prosthesis in the left side without warfarin anticoagulation therapy, but the high incidence of valve dysfunction in the pulmonary position does not justify its continued use in the right side.     

Clinical comparison of St. Jude and porcine mitral valve prostheses

One hundred and six consecutive patients who had mitral valve replacement with either a St. Jude or porcine heterograft prosthesis were prospectively studied. The 2 groups are similar with respect to 67 clinical and operative factors and allow comparison of valve performance as an independent variable. Total follow-up is 3,312 patient-months (mean 36 months, range 2-57 months, 94% complete). There are no statistical differences in symptomatic improvement or mortality by life table analysis. Valve-related complications expressed as percent per patient-year are: reoperation: 1.8 St. Jude and 3.8 porcine; endocarditis: 1.2 and 1.9; regurgitant murmur: 2.3 and 1.9; hemolysis: 1.8 and 0.0; late thromboembolism: 1.8 and 1.0; hemorrhage: 2.9 and 2.9; and valve failure: 0.0 and 1.0. There were no significant differences found. Actuarial survival at 3 years was 78% in St. Jude and 81% in porcine patients. Forty-six percent of patients with St. Jude valves and 55% of patients with porcine valves were alive and free of all complications at latest follow-up. The clinical performance of St. Jude and porcine mitral valves are similar over this period of intermediate follow-up.     

Clinical performance of St. Jude and Medtronic-Hall prostheses: a randomized comparative study

Newer and improved models of mechanical prostheses are regularly added to surgeons' armamentarium. This study was designed to compare the clinical performance of two of the most used current models of mechanical prostheses. From August 1983 through July 1985, 182 white patients were prospectively randomized to implantation of the St. Jude Medical (95 patients) or Medtronic-Hall (87 patients) prostheses. There were 84 mitral, 85 aortic, and 13 double (mitral and aortic) valve replacements. There were no differences between the two groups with regard to sex distribution, age, functional class, emergency operation, and site of implantation. Early mortality was 3.2% for patients with the St. Jude valve and 5.7% for those with the Medtronic-Hall (p = NS). The survivors were followed for 3 to 5 years (mean, 4.2 +/- 0.6 years; cumulative follow-up, 559 patient-years). Late mortality was 7.1%/patient-year for the St. Jude group and 3.2%/patient-year for the Medtronic-Hall group (p less than 0.05). However, the valve-related mortality was equal (1.4%/patient-year) for both groups. Noncardiac causes accounted for most of the difference between the St. Jude and Medtronic-Hall groups (2.5%/patient-year and 0.4%/patient-year, respectively). There were no cases of thrombotic obstruction, whereas serious systemic thromboembolism occurred at the rate of 1.8%/patient-year (5 episodes) for the St. Jude group and 2.5%/patient-year (7 episodes) for the Medtronic-Hall group (p = not significant); there were another nine episodes of systemic embolism that left no sequelae. Three patients (St. Jude, 2; Medtronic-Hall, 1), all of whom had aortic valve replacement, required reoperation (0.5%/patient-year) because of prosthetic endocarditis, with two deaths.(ABSTRACT TRUNCATED AT 250 WORDS)     

Leaflet arrest in St Jude Medical and CarboMedics valves: an experimental study

Objective: Two patients who suffered acute failure of their St Jude Medical Masters aortic valve prostheses due to leaflet arrest that were unrelated to suture material are presented. It was hypothesized that the valves failed because force applied to bear upon the valve annulus caused the hinge mechanism to become restricted or to arrest. Methods: A study was designed to measure the force that would cause leaflet arrest in three sizes of St Jude Medical Masters valves and CarboMedics mechanical valves. A specially manufactured pushrod device was used to apply a variable force to the sewing cuff, low annulus level, or to the pivot guards of all the valves. Results: For every valve size tested, the St Jude Medical Masters valves required significantly less force applied than did the CarboMedics valves to cause one or both leaflets to arrest (P<0.0004). Conclusions: A force applied on the valve ring of mechanical valves can cause leaflet arrest. The force required to arrest the leaflets is within an order of magnitude of that measured in other in vivo animal studies. We conclude that force on the valve rings in patients after aortic valve surgery could cause leaflet malfunction and even arrest in some patients.     

Mechanical cardiac valvular prostheses

Mechanical cardiac valvular prostheses currently enjoy a 60% to 40% market-share advantage over tissue prostheses in the United States and worldwide. Only the Starr-Edwards caged Silastic (Dow Corning) ball, Medtronic-Hall, St. Jude Medical, and Omniscience valves remain available in the United States. Although each valve has certain advantages and disadvantages, no design has achieved functional mechanical perfection. Late follow-up of valve-related complications from the literature favors the St. Jude Medical and Medtronic-Hall valves.     

"Our complication rates are lower than theirs": statistical critique of heart valve comparisons

OBJECTIVES: From the widely differing complication rates published for every heart valve, is it possible to determine a true rate for each valve and to compare the rates of two different valves? We investigated this question for the two most popular bileaflet valves. METHODS: Aortic valve data were abstracted from 14 St Jude Medical (St Jude Medical Inc, Minneapolis, Minn; 33,125 patient-y) and 11 Carbomedics (Sulzer Carbomedics Inc, Austin, Tex; 19,141 patient-y) series, and mitral valve data were abstracted from 11 St Jude Medical (21,553 patient-y) and 8 Carbomedics (8368 patient-y) series. Regression analysis was used to accommodate heterogeneity among rates with the same valve model, to estimate hazard ratios and 95% confidence intervals for the valve model effect, and to incorporate other series-level risk factors. RESULTS: Most of the complication rates with both valve models exhibited significant heterogeneity. For thromboembolism and bleeding, the relative risks for valve model were not significantly different from unity. Valve thrombosis rates exhibited less heterogeneity: the Carbomedics valve had a lower rate in the aortic position (hazard ratio 0.2, 95% confidence interval 0.1-0.6) and a higher rate in the mitral position (hazard ratio 1.9, 95% confidence interval 1.0-3.8). CONCLUSIONS: Unlike simple weighted averages of valve complication rates, regression methods can incorporate heterogeneity related to center effects and allow for inclusion of other risk factors. Thromboembolism and bleeding rates were not significantly different with St Jude Medical and Carbomedics valves. Valve thrombosis appeared to differ between the two valves, but the absolute differences in rates were small. Because of the variability among rates with the same valve, statistical comparisons must be interpreted cautiously.     

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.