Jude Medical Valve Research Articles

Effect of the flow field of mechanical bileaflet mitral prostheses on valve closing

Antianatomically installed Jyros (JR) and ATS valves were compared with the St. Jude Medical (SJM) valve in the mitral position to study the effects of valve design on the downstream flow field and associated closing sounds using a particle image velocimetry (PIV) method utilizing a high-speed video flow visualization technique to map the velocity field and sound measurement to confirm claims by the manufacturer. Based on the experimental data, the following general conclusions can be made: in the velocity field directly below the mitral valve, where distinct characteristic differences in valve design can be seen, symmetrical twin circulations were observed because of the divergent nature of the flow generated by the two inclined half-disks installed in the antianatomical orientation; the SJM valve, which produced central downward circulation, is contrasted to the two other valves, which produced peripheral downward circulation. These differences may play an important role in the closing behavior of the valve leaflets, thus affecting the generation of the valve closing sound.

Time-resolved particle image velocimetry and laser doppler anemometry study of the turbulent flow field of bileaflet mechanical mitral prostheses

Dynamic particle image velocimetry (PIV) was applied to the study of the flow field associated with prosthetic heart valves. The results were compared with those of laser Doppler anemometry (LDA). Anatomically and antianatomically oriented Jyros (JR) and St. Jude Medical (SJM) valves were compared in the mitral position to study the effects of valve design on the downstream flow field. The experimental program used a dynamic PIV system utilizing high-speed, high-resolution video to map the true time-resolved velocity field inside the simulated ventricle. This system was complemented by a study using the more traditional LDA system for comparison. Based on the experimental data, the following general conclusions can be made. High-resolution dynamic PIV can capture true chronological changes in the velocity and turbulence fields. It also produces very detailed velocity and turbulence information comparable to the LDA results. In the vertical measuring plane that passes both the center of the aortic and mitral valves (A-A section), the two valves (the SJM and the JR) show distinct circulatory flow patterns when the valve is installed in the antianatomical orientation. Small differences in valve design can generate noticeable differences, particularly during the accelerating flow phase. The SJM valve maintains a relatively high velocity through the central orifice; the curved leaflets of the JR valve generate higher velocities with a divergent flow during the accelerating and peak flow phases. In the velocity field directly below the mitral valve and normal to the previous measuring plane (B-B section), where characteristic differences in valve design will be visible, symmetrical twin circulations were observed because of the divergent nature of the flow generated by the two inclined half-disks installed in the antianatomical orientation. The SJM valve, with a central downward flow near the valve, is contrasted with the JR valve, which has a peripheral downward circulation with higher, turbulent stresses.

Carpentier-Edwards pericardial aortic valve in middle-aged patients comparison with the St. Jude medical valve

The objective of the present study was to compare long-term results of single aortic valve replacement (AVR) with mechanical (St. Jude Medical valves: standard) and biologic (the Carpentier-Edwards pericardial) prostheses. Between 1995 and 2002, 95 patients who underwent single AVR with mechanical (n= 46) or biologic (n= 49) prostheses were enrolled in this study. The mean age at the operation was 54.0 +/- 9.6 years (range: 20 to 69 years) with the mechanical and 68.8 +/- 7.1 years (range: 44 to 85 years) with the biologic prosthesis. The 9-year actuarial survival rate, which was calculated by taking perioperative mortality into account, was 90.3 +/- 4.6% for patients with mechanical valves and 87.6 +/- 4.8% for patients with bioprostheses, with no difference between the two groups (p=0.342). The 9-year freedom rate from thromboembolism, reoperation, endocarditis was 94.8 +/- 3.6%, 100% and 97.8 +/- 2.2% for patients with mechanical valves and 98.0 +/- 2.0%, 97.5 +/- 3.4% and 95.0 +/- 3.4% for those with bioprostheses, respectively. After 9 years, freedom from cardiac death averaged 97.8% in the group with mechanical valves compared with 95.3% in those with bioprostheses (p=0.541). We conclude that the mid-term durability of the Carpentier-Edwards pericardial valve in the aortic position for the elderly is excellent. Nevertheless, the risk of tissue valve reoperation progressively increases with time, and a longer follow-up may be necessary to provide its value compared with the mechanical valves in a country like Japan with a high life expectancy.

INVITED COMMENTARY

The search for the ideal pulmonary valve substitute continues to challenge surgeons, and the choice of prosthesis remains an important decision in clinical practice. Although bioprostheses and homografts are most commonly used for pulmonary valve replacement (PVR), limited durability necessitates reoperation for most patients. Late results of mechanical valves in the pulmonary position are conflicting. Indeed, in the few available reports, mechanical valve thrombosis occurred in 25% to 56% of patients [1Ilbawi M.N. Lockhart C.G. Idriss F.S. et al.Experience with St. Jude Medical valve prosthesis in children: a word of caution regarding right-sided placement.J Thorac Cardiovasc Surg. 1987; 93: 73-79PubMed Google Scholar, 2Ilbawi M.N. Lockhart C.G. Idriss F.S. et al.Valve replacement in children: guidelines for selection of prosthesis and timing of surgical intervention.Ann Thorac Surg. 1987; 44: 398-403Abstract Full Text PDF PubMed Scopus (45) Google Scholar, 3Miyamura H. Kanazawa H. Hayashi J. et al.Thrombosed St. Jude valve prosthesis on the right side of the heart in patients with Tetralogy of Fallot.J Thorac Cardiovasc Surg. 1987; 94: 148-150PubMed Google Scholar]. However, it is important to note that inadequate anticoagulation or no anticoagulation was documented in many patients who had thrombotic complications develop in many of these retrospective reviews. Haas and colleagues report their results of 14 patients (average age 24.8 yr) who after several prior operations underwent PVR with a mechanical valved conduit. There were no valve-related complications during short-term follow-up (mean age, 2.9 yr), and all patients were anticoagulated with warfarin with a target international normalized ratio of 3.0 to 4.5. The important point of this report in contrast to prior studies is the absence of valve thrombosis. Their technique of valve implantation employs a Dacron conduit, and a limitation of this report is the lack of truly late results with the use of a conduit as a part of their reconstruction. In most older patients, an adequate sized pulmonary prosthesis can be inserted with no prosthetic material or by using only an anterior patch of pericardium to augment the valve annulus. The potential disadvantage of preferential use of valved conduits is late development of obstructive intimal fibrocalcific peels within the right-sided Dacron conduits [4Agarwal K.C. Edwards W.D. Feldt R.H. et al.Clinicopathological correlates of obstructed right-sided porcine-valved extracardiac conduits.J Thorac Cardiovasc Surg. 1981; 81: 591-601PubMed Google Scholar]. We have utilized a mechanical prosthesis in 17 adult patients who required PVR (0.7% of all PVR performed at our clinic), and in late follow-up of the first 10 patients (mean follow-up, 8.3 yr; maximum follow-up, 25 yr) there was no instance of valve thrombosis. Our implantation technique differs in that we prefer to perform an isolated PVR with patch reconstruction of the previous conduit bed or native pulmonary artery using autologous or bovine pericardium. Currently we consider mechanical PVR for patients who have had multiple prior operations, or who are on warfarin for another reason. In general, we have not advised mechanical PVR in children, but would give consideration to mechanical PVR if anticoagulation is required for a mechanical prosthesis on the left side of the heart. In addition to adequate anticoagulation with warfarin (target international normalized ratio, 3.0 to 4.0), antiplatelet therapy should be considered [5Salem D.N. Stein P.D. Al-Ahmad A. et al.Antithrombotic therapy in valvular heart disease – native and prosthetic: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy.Chest. 2004; 126 (457S–82S)PubMed Google Scholar]. These measures will not prevent valve thrombosis in all patients, and regular surveillance with Doppler echocardiography is necessary. If valve thrombosis is detected, initial treatment by optimizing anticoagulation with or without thrombolysis may be sufficient to restore valve function and avoid reoperation. Thrombolytic therapy of tricuspid and pulmonary mechanical valves would be expected to have fewer serious complications compared with prostheses in the aortic and mitral positions [6Lengyel M. Fuster V. Keltai M. et al.Guidelines for management of left-sided prosthetic valve thrombosis: a role for thrombolytic therapy Consensus Conference on Prosthetic Valve Thrombosis.J Am Coll Cardiol. 1998; 32: 550-551PubMed Google Scholar, 7Bolz D. Kuhne T. Jivraj R. et al.Thrombolysis of prosthetic tricuspid valve thrombosis with human recombinant tissue plasminogen activator in an adolescent.Pediatr Cardiol. 2000; 21: 397-400Crossref PubMed Scopus (11) Google Scholar].

Reoperation of the Kay-Shiley Disc Valve 35 Years After Replacement

The Kay-Shiley disc valve (Shiley Inc, Irvine, CA) was manufactured in 1965 and is no longer in clinical use due to its high incidence of thromboembolism. We report a case of tricuspid valve replacement with the Kay-Shiley valve 35 years previously. The valve was replaced successfully with a St. Jude Medical valve (St. Jude Medical, Inc, St. Paul, MN). This is the longest interval from implantation to re-replacement with the Kay-Shiley valve that has been reported in the literature.

The St. Jude Medical Cardiac Valve Prosthesis: A 25-Year Experience With Single Valve Replacement

From October 1977 to October 2002, 4,480 patients (age range, 17 to 94 years; average, 64 +/- 13 years) underwent single valve replacement with the St. Jude Medical heart valve. Of 2,982 aortic (AVR) and 1,498 mitral valve replacements (MVR), concomitant coronary artery bypass grafting was performed on 42% and 33%, respectively. Cardiac Surgical Associates has maintained an independent database of patients having valve replacement with the St. Jude Medical prosthesis since the world's first implant. Patients were contacted by questionnaire or phone from November 2002 through June 2003. Hospital course and valve-related events were verified by patient chart review or physician contact. Follow-up was 95% complete. Operative mortality was 4% with AVR and 9% with MVR. Total follow-up was 32,190 patient-years (range, 1 month to 24.8 years; average, 7 +/- 5 years). During the study period, patient freedom from late mortality was 61% (AVR, 61%; MVR, 63%), and from valve-related mortality 92% (AVR, 93%; MVR, 91%). Freedom from thromboembolic events was 85% (86% AVR, 81% MVR), from bleeding events, 81% (81% AVR, 81% MVR), from reoperation, 98% (99% AVR, 97% MVR), from endocarditis, 98% (99% AVR, 98% MVR), and from valve thrombosis, 99% (99% AVR, 98% MVR). There was one MVR structural failure (0.06%). The St. Jude Medical valve has proven to be an effective and durable valve prosthesis with a low event rate during the long term.

INVITED COMMENTARY

This article by Emery and colleagues represents a unique experience by a premier surgical group. As noted by the authors, inherent thrombogenicity of the prosthesis and the resultant need for anticoagulation remain the major causes of valve-related events in these patients. At 15 years, the cumulative incidences of thromboembolic and hemorrhagic events reach 15% and 21%, respectively with aortic replacements and they reach 20% and 20%, respectively with mitral valve replacements. These values are important, as nearly 50% of patients are still alive at 15 years. More importantly, there were 61 fatal thromboembolic events after aortic valve replacement (or 14% of all thromboembolic events after aortic valve replacement). Similarly, 15% of thromboembolic events after mitral valve replacement were fatal (45 of 293) as were 11% of hemorrhagic events after aortic valve replacement (63 of 589), and 7% of hemorrhagic events after mitral valve replacement (21 of 285). These consequences of mechanical valves are clearly not insignificant and underscore the comments by the authors that optimization of anticoagulation therapy with home monitoring or alternative thrombin inhibitors, or both, will be important in maximizing the efficacy and safety of mechanical valves in the future. The authors also note that despite the outstanding durability of the prosthesis, patients having valve replacement do not survive in parallel with the normal population. (Life tables from the middle part of the study period do indeed indicate that the average life expectancy of a 60-year-old in the United States is approximately 20 years.) The authors suggest that this dichotomy results from patient-related, rather than valve-related factors, and that the recorded valve-related mortality is actually overstated because the most common cause of valve-related mortality is sudden death. However, the role of the prosthesis itself in late mortality remains unconfirmed, as deaths were not correlated with either valve gradients or the extent of left ventricular mass regression in individual patients. The mere presence of a rigid prosthesis where pliable tissue is normally found may contribute to late mortality in some patients, as has been suggested by proponents of stentless valves. Although these and other issues will continue to fuel debate over the optimal valve replacement, the report by Emery and colleagues clearly documents the durability and efficacy of the St. Jude Medical valve, and their results can serve as a benchmark for others. The St. Jude Medical Cardiac Valve Prosthesis: A 25-Year Experience With Single Valve ReplacementThe Annals of Thoracic SurgeryVol. 79Issue 3PreviewFrom October 1977 to October 2002, 4,480 patients (age range, 17 to 94 years; average, 64 ± 13 years) underwent single valve replacement with the St. Jude Medical heart valve. Of 2,982 aortic (AVR) and 1,498 mitral valve replacements (MVR), concomitant coronary artery bypass grafting was performed on 42% and 33%, respectively. Full-Text PDF

Thromboembolic and Bleeding Complications Following St. Jude Medical Valve Replacement: Results of the German Experience With Low-Intensity Anticoagulation Study

Study objectives Due to their inherent thrombogenicity, mechanical cardiac valves necessitate lifelong oral anticoagulation. Less intensive oral anticoagulation than recommended earlier might result in a lower incidence of bleeding complications without increasing the embolic hazard significantly. Design Comparison of three different intensities of oral anticoagulation in a prospective, randomized multicenter design. Three months after valve replacement, patients were randomly assigned to stratum A, international normalized ratio (INR) 3.0 to 4.5; stratum B, INR 2.5 to 4.0; or stratum C, INR 2.0 to 3.5. Patients Data from 2,735 patients following aortic valve replacement (AVR; n = 2,024), mitral valve replacement (MVR; n = 553), and combined AVR and MVR (n = 158) with the St. Jude Medical (SJM) valve (St. Jude Medical; St. Paul, MN) between July 1993 and May 1999 were analyzed, covering a total follow-up period of 6,801 patient-years. All complications were registered prospectively. Measurements and results Fifty-one thromboembolic events (TEs) were documented, resulting in a linearized incidence of 0.75 TEs per 100 patient-years, 22 of which were minor (0.32% per patient-year), 10 were moderate (0.15% per patient-year), and 19 were severe (0.28% per patient-year). Thromboembolism following AVR was significantly lower than after MVR (0.53% per patient-year vs 1.64% per patient-year). Patients reported 1,687 bleeding complications (24.8% per patient-year). The vast majority of bleeding complications (n = 1,509; 22.2% per patient-year) were classified as minor, 140 were classified as moderate (2.06% per patient-year), and 38 were classified as severe (0.56% per patient-year). The clinically relevant incidences of moderate and severe TEs and bleeding complications were not significantly different between the three prespecified INR strata. Conclusions The intention-to-treat analysis of the results of the German Experience With Low Intensity Anticoagulation study leads to the unexpected result that despite a sophisticated reporting system, the incidence of moderate and severe TE and bleeding complications was comparably low in all INR strata and more or less within the so-called background incidence reported for an age-related “normal” population. This study supports reexamination of the intensity of anticoagulation in patients with the SJM valve. Due to their inherent thrombogenicity, mechanical cardiac valves necessitate lifelong oral anticoagulation. Less intensive oral anticoagulation than recommended earlier might result in a lower incidence of bleeding complications without increasing the embolic hazard significantly. Comparison of three different intensities of oral anticoagulation in a prospective, randomized multicenter design. Three months after valve replacement, patients were randomly assigned to stratum A, international normalized ratio (INR) 3.0 to 4.5; stratum B, INR 2.5 to 4.0; or stratum C, INR 2.0 to 3.5. Data from 2,735 patients following aortic valve replacement (AVR; n = 2,024), mitral valve replacement (MVR; n = 553), and combined AVR and MVR (n = 158) with the St. Jude Medical (SJM) valve (St. Jude Medical; St. Paul, MN) between July 1993 and May 1999 were analyzed, covering a total follow-up period of 6,801 patient-years. All complications were registered prospectively. Fifty-one thromboembolic events (TEs) were documented, resulting in a linearized incidence of 0.75 TEs per 100 patient-years, 22 of which were minor (0.32% per patient-year), 10 were moderate (0.15% per patient-year), and 19 were severe (0.28% per patient-year). Thromboembolism following AVR was significantly lower than after MVR (0.53% per patient-year vs 1.64% per patient-year). Patients reported 1,687 bleeding complications (24.8% per patient-year). The vast majority of bleeding complications (n = 1,509; 22.2% per patient-year) were classified as minor, 140 were classified as moderate (2.06% per patient-year), and 38 were classified as severe (0.56% per patient-year). The clinically relevant incidences of moderate and severe TEs and bleeding complications were not significantly different between the three prespecified INR strata. The intention-to-treat analysis of the results of the German Experience With Low Intensity Anticoagulation study leads to the unexpected result that despite a sophisticated reporting system, the incidence of moderate and severe TE and bleeding complications was comparably low in all INR strata and more or less within the so-called background incidence reported for an age-related “normal” population. This study supports reexamination of the intensity of anticoagulation in patients with the SJM valve.

A207 Dynamic PIVによる機械的人工心臓僧帽二葉弁まわりの流れ解析

Three bi-leaflet prostheses (St. Jude Medical, Jyros and On-X valve), were tested in the mitral position under the pulsatile-flow condition. The Dynamic PIV system was employed to analyze the flow field affected by the leaflet shapes and valve designs. The Dynamic PIV system allows to acquire 1000 time-varying velocity fields at 1kHz by using Nd:YLF laser, which is synchronized with a high resolution camera (1024×1024 pixel). Detailed chronological comparison of the flow fields associated with the opening, accelerating, peak and closing phase of the flow revealed the significance of the leaflet and overall valve designs on the flow field. The small difference in leaflet configuration in the bi-leaflet prostheses generates noticeable differences on the flow.

Reply to Fortune' Letter to the Editor: Leaflet arrest in St Jude Medical and CarboMedics valves: an experimental study by Grattan and associates

Reply to Fortune' Letter to the Editor: Leaflet arrest in St Jude Medical and CarboMedics valves: an experimental study by Grattan and associates

A long-term porcine model for evaluation of prosthetic heart valves.

Animal experimental testing is imperative for preclinical evaluation of prosthetic heart valves and implantation techniques. Because human and pig cardiovascular structures including mitral valves show remarkable anatomical similarity, these animals are good candidates for preclinical testing. Previous attempts to establish such long-term models were hampered by both intra- and postoperative difficulties. Our aim was to overcome these difficulties to develop a porcine model for mitral valve replacement (MVR) and furthermore to investigate the practical feasibility of 3 chordal reconstruction procedures. Sixteen 60-kg pigs were allocated to undergo 1 of 3 surgical procedures, (1) preservation of the entire subvalvular apparatus (n = 8), (2) preservation of the secondary chordae only (n = 4), or (3) excision of the native valve and papillary resuspension with sutures (n = 4). St. Jude Medical valves (29 mm) were implanted during extracorporeal circulation and cold cardioplegic arrest. Postoperative anticoagulation was administered by subcutaneous heparin injections. Fourteen animals survived 1 month, thriving and without signs of heart failure. One animal was euthanized due to irreversible bleeding in the tracheal tube, and another animal died on the third postoperative day owing to valve thrombosis. A practically feasible long-term porcine model of MVR has been established. Because the pig is superior to other species with respect to anatomical and physiological similarity to humans, we consider this model as an optimal platform for experimental preclinical testing of heart valve prostheses.

Obstruction of St Jude Medical valves in the aortic position

Obstruction of St Jude Medical valves in the aortic position

Obstruction of St Jude Medical valves in the aortic position

Obstruction of St Jude Medical valves in the aortic position

Thrombolytic therapy for prosthetic valve thrombosis in children: two case reports and review of the literature

Thrombotic occlusion of a mechanical valve prosthesis can be life threatening and requires urgent evaluation and treatment. Traditionally, the treatment for mechanical valve thrombosis has been urgent reoperation with attempted declotting of the valve or valve rereplacement. Unfortunately, this is associated with a high mortality, and efforts have been made to pursue nonoperative treatment with thrombolytics. There are many reports of the successful use of thrombolytics in adults, but very little data are reported in the pediatric population. We review the literature, report 2 cases of successful treatment of mechanical mitral valve thrombotic occlusion with thrombolytic therapy in children, and summarize the major reports of thrombolytic use for prosthetic valve occlusion in the pediatric population.

High-intensity transient signals due to prosthetic valve obstruction: diagnostic and therapeutic implications

Background High-intensity transient signals (HITS) can be detected by transcranial Doppler ultrasonography (TCD) in patients carrying a mechanical prosthetic valve. The HITS counts and a frequency analysis were evaluated in patients with prosthetic valve obstruction in the aortic position. Methods Simultaneous echocardiographic, cineradiographic, and TCD evaluations for a St. Jude Medical valve were performed in 108 patients. All patients were asymptomatic and had no significant stenosis of the carotid artery. The HITS were identified according to criteria established by consensus of the International Cerebral Hemodynamics Symposium. Results The HITS counts in 69 patients with normal prosthetic valve function were 2.2 ± 4.4, and the counts in 39 patients with prosthetic valve obstruction (group D) were 8.3 ± 10.8. This difference was significant ( p = 0.0002). In 2 patients of group D who had a greater rate of less than 400 Hz HITS, which were produced by solid microemboli, thrombolysis resulted in a mitigation of restricted leaflet movement equal to or greater than 10 o. The total number of HITS decreased and the rate of less than 400 Hz HITS also markedly decreased after thrombolysis in these 2 patients. On the other hand, 4 patients who obtained no improvement of leaflet movement by thrombolysis had lower rates of less than 400 Hz HITS than did the 2 patients. Conclusions These results suggest that measurement of HITS counts is useful for detection of prosthetic valve obstruction, and that a frequency analysis of HITS may be valuable to clarify the cause of the obstructed prosthetic valves.

1048-136 Long-term results with the St. Jude medical aotic valve: A 25-year experience

1048-136 Long-term results with the St. Jude medical aotic valve: A 25-year experience

1143-140 Reoperative valve replacement with the St. Jude medical valve prosthesis: Long-term follow-up

1143-140 Reoperative valve replacement with the St. Jude medical valve prosthesis: Long-term follow-up

Usefulness of a multidetector-row computed tomography scanner for detecting pannus formation

Background Prosthetic valve dysfunction (PVD) as a result of pannus or thrombus formation is an infrequent but serious complication. Currently available diagnostic tools, however, are insufficient to detect a minute pannus and thrombi. The use of a more advanced diagnostic image, multidetector-row computed tomography scanner, may enable us to determine the anatomic and functional causes of PVD. Methods Patients who underwent aortic valve replacement with a St. Jude Medical valve were examined by transthoracic echocardiography and cineradiography to diagnose PVD. Sixteen patients with PVD (PVD group) and 12 patients with normal prosthetic valve function (control group) were studied using the multidetector-row computed tomography scanner. The multidetector-row computed tomography findings in 2 patients with PVD were validated by the observations during reoperation. Results In 13 of 16 patients (81%) in the PVD group and 3 of 12 patients (25%) in the control group, multidetector-row computed tomography demonstrated that an abnormal small tissue, regarded as pannus, was found to extend from the left ventricular septum into the pivot guard. These findings were confirmed by the observations during reoperation in 2 patients in the PVD group. Conclusions Multidetector-row computed tomography can be a useful diagnostic technique for anatomic and functional evaluation of PVD as a result of pannus formation.

Obstruction of st jude medical valves in the aortic position: histology and immunohistochemistry of pannus

Objective This study aims to reveal the morphological, histological, and immunohistochemical mechanism of pannus formation using resected pannus tissue from patients with prosthetic valve dysfunction. Method Eleven patients with prosthetic valve (St Jude Medical valve) dysfunction in the aortic position who underwent reoperation were studied. We used specimens of resected pannus for histological staining (hematoxylin and eosin, Grocott’s, azan, elastica van Gieson) and immunohistochemical staining (transforming growth factor-beta, transforming growth factor-beta receptor 1, α-smooth muscle actin, desmin, epithelial membrane antigen, CD34, factor VIII, CD68KP1, matrix metalloproteinase-1, matrix metalloproteinase-3, and matrix metalloproteinase-9). Results Pannus without thrombus was observed at the periannulus of the left ventricular septal side; it extended into the pivot guard, interfering with the movement of the straight edge of the leaflet. The histological staining demonstrated that the specimens were mainly constituted with collagen and elastic fibrous tissue accompanied by endothelial cells, chronic inflammatory cells infiltration, and myofibroblasts. The immunohistochemical findings showed significant expression of transforming growth factor-beta, transforming growth factor-beta receptor 1, CD34, and factor VIII in the endothelial cells of the lumen layer; strong transforming growth factor-beta receptor 1, α-smooth muscle actin, desmin, and epithelial membrane antigen in the myofibroblasts of the media layer; and transforming growth factor-beta, transforming growth factor-beta receptor 1, and CD68KP1 in macrophages of the stump lesion. Conclusions Pannus appeared to originate in the neointima in the periannulus of the left ventricular septum. The structure of the pannus consisted of myofibroblasts and an extracellular matrix such as collagen fiber. The pannus formation after prosthetic valve replacement may be associated with a process of periannular tissue healing via the expression of transforming growth factor-beta.

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.