Bileaflet Valve Research Articles

Prosthetic Heart Valve Thrombosis

A 71-year-old man with prior history of mechanical bi-leaflet aortic valve replacement (AVR) presented with new-onset ataxia and left-sided weakness. Computed tomography (CT) of the brain revealed ...

Clinical profile of prosthetic heart valve thrombosis and outcome analysis of fibrinolytic therapy versus surgical management: A single-center experience

Context: The main aim of the study is to find out efficacy, outcomes, and complications of thrombolytic therapy and surgery for obstructive prosthetic heart valve thrombosis (PHVT).Materials and Methods: This was a prospective, observational study done on 130 patients with PHVT, from January 2016 to December 2017. Baseline details, clinical investigations, echocardiography, and fluoroscopy were done. In fibrinolytic therapy, group agents used were streptokinase and urokinase. Out of 130, 115 patients were followed for up to 6 months after the discharge.Results: Majority of the patients were females (66.9%). Sixty-five (50%) patients were in the New York Heart Association Class III, whereas 55 (42.3%) and 10 (7.7%) patients were in Class IV and II, respectively. Nearly 34.6% patients had AF, and remaining 63.1% had sinus rhythm. Out of 130 patients, 26 (20%) patients had single-leaflet valve and 103 (79.2%) patients had bileaflet valve, and only one patient had ball and cage type of the valve. Out of 130 patients, 81 (62.3%) patients received fibrinolytic therapy as the first-line therapy and 49 (37.7%) patients underwent surgery initially. In fibrinolytic therapy group, three patients underwent surgery due to failed fibrinolytic therapy. Fifty-three patients (65.5%) had complete hemodynamic and clinical success without any complications; 28 patients (34.5%) had failure. Of 130 patients, 49 patients underwent surgery as the initial treatment. In the surgical group, three patients died out of 52 patients; mortality rate was 5.80%.Conclusion: Surgery should be offered to patients with contraindications for fibrinolytic therapy as in case of recurrent PHVT surgery offers better outcome with lesser recurrences when compared with fibrinolytic therapy.

1642 Mitral annulus disjunction, a rare form of focal arrhythmogenic cardiomyopathy

Abstract Funding Acknowledgements Project no. NVKP_16-1-2016-0017 has been implemented with the support provided from the National Research, Development and Innovation Fund of Hungary The rate of sudden cardiac death in mitral valve prolapse (MVP) patients is roughly twice that observed in the general population. Arrhythmogenic bileaflet MVP syndrome has been recently described and mitral annulus disjunction (MAD) has been found associated with papillary muscle fibrosis and ventricular arrhythmias even without severe mitral regurgitation. An underlying primary structural myocardial disease might be expected and the non-invasive imaging techniques are playing an increasingly important role in the detection of myocardial fibrosis as a focal arrhythmogenic substrate. Standard 2D-, 3D- and speckle tracking echocardiography and cardiac MRI can help to differentiate between the benign and malignant forms of MVP. A 52-year-old man with a history of hypertension was referred for evaluation of frequent palpitations and presyncope. Ambulatory Holter monitoring showed paroxysmal atrial fibrillation and non-sustained ventricular tachycardias. Dilated left ventricle (LVEDD: 65mm, LVESD: 45 mm) and left atrium (LAVi: 52mL/m2), moderately reduced left ventricular (LV) systolic function (LVEF: 42%), and reduced LV global longitudinal strain (GLS: -13.5%) with severely decreased segmental longitudinal strain in the basal inferolateral segment were measured by transthoracic echocardiography. The diastolic function was preserved, however Pickelhaube sign was noticed in the lateral mitral annulus TDI curves. MAD (17 mm) and curling motion of the inferolateral basal segment of the left ventricle was observed. Transesophageal echocardiography showed bileaflet mitral valve prolapse with the involvement of all the six scallops (mitral valve prolapse volume: 10.2 mL). Severe mitral regurgitation (3D vena contracta area: 1cm2) and extremely dilated and dyskinetic mitral annulus (diameters: 55x72x12 mm, area: 34 cm2) was measured by 3D echocardiography. MRI showed transmural late gadolinium enhancement in the underlying myocardium of both papillary muscles and midmyocardial enhancement in the basal inferior, inferolateral and anteroseptal LV segments. During electrophysiology study ventricular fibrillation was easily induced and ICD was placed for primary prevention of sudden cardiac death. The patient was referred to the heart surgeon for mitral valve replacement. This case highlights the importance of early recognition of MAD and arrhythmogenic MVP syndrome using novel non-invasive imaging techniques. The presence of MAD, the curling motion of the inferolateral basal LV segment, the Pickelhaube sign, the decreased LVEF and GLS, the characteristic segmental longitudinal strain pattern and the presence of late enhancement in the papillary muscles and the surrounding myocardium could be warning signs of the malignant form of MVP. Abstract 1642 Figure. CMR images of arrhythmogenic MAD

P806 Cavitation phenomenon in mechanical valves: not only microbubbles

Abstract Introduction It is well described the presence of microbubbles (MBs) which are high-velocity, small, bright echoes presences that occur with the closing/opening of the mechanical double disk valve, more frequently in mitral position but less frequent growth of the cavitation bubbles are described. We considered the echo studies of patients with growth of cavitation bubbles and we evaluate the possible impact of the hemodynamic parameters of their formation and then misdiagnosis with endocarditis. Methods We analyzed retrospectively the echocardiographic studies of 49 patients with growth of cavitation bubbles and we went back to all studies until the date of surgery if available, to see in how many of those echos, this phenomenon was present. Patient"s blood pressure (BP) and heart rate (HR) measurement were available for each echo study. For the present analysis the last echo study with or without growth of cavitation bubbles were considered. The last echo study without growth of cavitation bubbles was considered as control group. Results Fourty nine patients (M26/F23) with mean age of 46.5 ± 13.6 years were identify as having growth of the cavitation bubbles and a total of 325 echo studies were reviewed. All patients had mitral valve replacement but 4, that had only aortic mechanical valve. 43% had mitral-aortic valve replacement and 5 had 3 or 4 valves replaced. The follow-up period was of 3697 ± 2481 days, 52%±31% of the echo studies reviewed had growth of the cavitation bubbles. At the time of the study systolic BP was 124 ± 12.5 vs 121.1 ± 16.4 mmHg, p = 0.1 (echo study with versus without growth cavitation respectively), diastolic 72.7 ± 10.1 vs 69.4 ± 14.9 mmHg, p= 0.2; HR 81.3 ± 19.4 vs 73.7 ± 14.1 bpm, p = 0.05. No statistical differences in trans mitral gradients were found between the two groups (peak 11.8 ± 3.9 vs 11.7 ± 4.3 mmHg, p = 0.7; mean 4.6 ± 1.9 vs 4.2 ± 1 mmHg.6p = 0.1). 33 TEE were performed and in 50% of cases because of suspecion of endocarditis. Only 2 TEE were positive for endocarditis and one positive for pannus and high gradients across the valve in addition to cavitation. Conclusion Cavitation phenomenon in mechanical valves, in particular mitral bi-leaflet valve is well known but growth of cavitation bubbles is seldom described. We found that this fenomenon is frequently present although not constant, is related with increased HR and can be responsible of misdiagnosis with endocarditis. Abstract P806 Figure.

Optimal oral anticoagulant therapy in Chinese patients with mechanical heart valves

Background: The oral administration of anticoagulants is an effective means of preventing thromboembolic complications in patients implanted with mechanical valves. This treatment strategy, however, entails a dose-dependent in the risk of hemorrhage that is a cause for concern in China. As such, in this study, we sought to better determine what the ideal oral anticoagulant therapy intensity is in a Chinese population of patients implanted with mechanical valves.Methods: In the present observational cohort study, we observed the outcomes of eligible enrolled patients that had been implanted with St. Jude Medical prosthetic valves and who had been treated at our institution from 2013 onwards. All enrolled patients were followed for between 1 and 6 years through outpatient visits or telephone interviews following discharge. Study endpoints included instances of thromboembolism and major hemorrhage. We calculated the international normalized ratio (INR)-specific incidence of such adverse events as a means of determining optimal anticoagulant therapeutic intensity in patients with these bileaflet mechanical valve prostheses.Results: In total this study enrolled 3176 patients, of whom 3017 were followed for 12,746.08 total person-years (4.22 mean years per patient), while the remaining 159 patients (5%) were lost during follow-up. A total of 182 patients suffered from adverse events, with a roughly 1.43% annual incidence rate of such adverse events (95% confidence interval [CI], 1.22–1.64). Of these, 54 patients suffered from episodes of major bleeding (0.42% per patient-year, 95% CI, 0.31–0.53), while 131 suffered from thromboembolism (1.03% per patient-year, 95% CI, 0.85–1.21). Based on these analyses, we determined that the ideal low-intensity anticoagulant treatment regimen for patients with bileaflet mechanical heart valve prostheses was an INR between 1.5 and 2.5. In those patients that had undergone aortic valve replacement (AVR), the optimal INR was between 1.5 and 2.0 regardless of any thromboembolism risk factors in these patients. In contrast, in patients that had undergone mitral valve replacement (MVR) who were not at risk for thromboembolism, the optimal INR was between 1.5 and 2.0, whereas in those at risk of thromboembolism the optimal INR was between 2.0 and 2.5. The ideal anticoagulant intensity in patients undergoing both AVR and MVR (DVR) was the same as in patients undergoing MVR alone.Conclusions: In order to achieve optimal outcomes by maintaining effective anticoagulant dosing while entailing minimal risk in Chinese patients that have undergone a bileaflet mechanical valve replacement, the target INR range should be between 1.5 and 2.5, with the final intensity of this anticoagulant regimen being determined based on a given patient's risk of thromboembolism.

Simultaneous Rupture of an Aortomitral Intervalvular Fibrosa Pseudoaneurysm to the Aorta and the Left Atrium

A 55-year-old man was admitted to our surgical ward with a diagnosis of an aorto-left atrial fistula. The diagnosis of infectious endocarditis had been ruled out in another hospital before the patient was referred to our hospital through multiple blood cultures, examinations of inflammatory markers, and the absence of signs and symptoms of infection. He had a history of aortic and mitral valve replacement with mechanical bileaflet valves 3 years earlier and had been on hemodialysis for several years. Physical examinations revealed a continuous murmur at the left parasternal border. Transthoracic and transesophageal echocardiographic examinations demonstrated mild left ventricular enlargement with a normal systolic function, a normal right ventricular size with systolic dysfunction, and normally functioning aortic and mitral prosthetic valves without any leakage or thrombosis. There was an echo-free space between the aortic and mitral valves that expanded in systole and decompressed in diastole with a connection to the left ventricular outflow tract, suggestive of the pseudoaneurysm of the aortomitral intervalvular fibrosa (AMIVF). This pseudoaneurysm was connected to the aorta on one side and to the left atrium on the other side, constituting a cavity between the ascending aorta and the left atrium that conducted a continuous flow from the aorta to the left atrium (Figure 1A and B; Video 1 and Video 2). Computed tomography angiography documented this space and its connection to the ascending aorta and the left atrium (Figure 2A, B, and C). It appears that surgical trauma was the most probable etiology of the pseudoaneurysm of the AMIVF in our patient. The patient refused surgical repair of this pseudoaneurysm. The AMIVF is a zone between the anterior mitral leaflet and the non-coronary and left coronary aortic cusp that is fibrotic and vascular. These properties predispose it to injury due to infection and surgical trauma as the most common etiologies for the pseudoaneurysm of the AMIVF. The pseudoaneurysm of the AMIVF can be complicated by fistulation to the adjacent structures such as the left atrium the and aorta, which has been reported in about 20% of patients with the pseudoaneurysm of the AMIVF.1 On the follow-up of patients with aortic or mitral valve replacement or both, the presence of a pseudoaneurysm in the AMIVF as an uncommon complication of such valve replacements should be considered at the time of physical examinations and echocardiography. J Teh Univ Heart Ctr 2019;14(4):195-197 This paper should be cited as: Mohseni-Badalabadi R, Hosseinsabet A, Mohseni-Badalabadi M, Forozannia K. Simultaneous Rupture of an Aortomitral Intervalvular Fibrosa Pseudoaneurysm to the Aorta and the Left Atrium. J Teh Univ Heart Ctr 2019;14(4):195-197.

The Study of Blood Hemodynamic and Thrombosis Formation in Bi-leaflet Mechanical Heart Valve of Different Configurations

Background: Bi-leaflet mechanical heart valve (MHV) device suffers from thrombosis formation issue. The abnormal blood flow through the MHV is said to be one of the factor of thrombus formation which is caused by the curvature angle design.

Minimal Access Versus Sternotomy for Complex Mitral Valve Repair: A Meta-Analysis

There is high demand for minimally invasive mitral valve repair; however, it is unclear whether the minimally invasive approach provides the same performance as conventional sternotomy in a context of complex mitral valve disease. Here, we compared outcomes of minimally invasive and sternotomy procedures for bileaflet and Barlow's mitral valve disease. We performed a pooled meta-analysis of studies reporting early and late follow-up of mitral valve repair for complex mitral valve regurgitation. The primary outcome was moderate mitral valve regurgitation recurrence and need for reoperation. Secondary outcomes included operation time, reopening for bleeding, associated tricuspid procedures, failed repair, and inhospital mortality. Incidence rates were calculated for long-term follow-up. Effect estimates were calculated as incidence rates with 95% confidence intervals. When Kaplan-Meier curves were available, event rates were estimated from the curves with Plot Digitizer software; otherwise, reported event rates were used to calculate incidence rates. Eighteen studies including 1905 patients (654 minimally invasive and 1251 sternotomy) with a mean follow-up of 51.6 months (range, 14 to 138) were meta-analyzed with a random model. There were no significant between-group differences in moderate mitral valve regurgitation recurrence and reoperation (minimally invasive vs sternotomy, 1.7% [95% confidence interval, 1.0% to 2.9%] vs 1.3% [95% confidence interval, 0.9% to 1.8%], P= .22). Patients in the minimally invasive group were exposed to significantly longer cross-clamp and cardiopulmonary bypass times (P < .01); however, there were no additional between-group differences in secondary outcomes. This meta-analysis has demonstrated that minimally invasive and sternotomy approaches produce comparable results for complex mitral valve repair.

Outcome of 40 consecutive cases of modified Ross procedure using novel Dacron valved conduit.

The Ross procedure is an established option for aortic valve disease in children. Due to limited availability of pulmonary homograft, we devised a novel technique for right ventricular outflow tract (RVOT) reconstruction by preparing indigenous Dacron valved conduit. Forty consecutive cases of modified Ross procedure done at our center (2013-2018) were analyzed. Thirty-seven patients (95%) were followed up with median duration of 2.5 (0.08-5.5) years. Median age was 12 (5-39) years. Nineteen (47.5%) patients had rheumatic aortic valve disease, while 19 (47.5%) had congenital aortic valve disease. Aortic root replacement with pulmonary autograft was performed in all patients. Dacron conduit for RVOT reconstruction was used with on table sewn bileaflet valve using Dacron patch (n = 22), expanded polytetrafluoroethylene (ePTFE) membrane (n = 10), bioprosthetic valve (n = 4), and pericardium (n = 4). Additional surgical procedures included mitral valve repair (n = 10), septal myectomy (n = 2), ascending aorta replacement (n = 1), ruptured sinus of valsalva (RSOV) repair (n = 1), and ventricular septal defect (VSD) closure (n = 1). There was one in-hospital mortality while one late death occurred at 3.5years postoperatively. The neo-aortic valve regurgitation on echocardiographic evaluation at last follow-up was trivial (n = 28), mild (n = 7), and moderate (n = 2). Mild RVOT obstruction was present in 8 patients while 18 patients had mild pulmonary regurgitation. No patient required reintervention during follow-up. Our early results of modified Ross procedure are encouraging, however, long-term follow-up is required.

Exergy Analysis of the Heart with a Stenosis in the Arterial Valve.

In the past decade, several articles have proposed the use of an exergy perspective to analyze physiological systems of the human body under different physical conditions. Such a perspective focuses on the exergy transformations and the efficiency of the biological processes. This may aid the medical field in assessments of a patient’s physical health by means of an index (exergy efficiency) based on the quality of the energy conversion in a given process within the human heart. As a follow-up, a model was developed to describe the evolution of the transvalvular pressure gradient in the aortic valve as a function of stenosis severity. This model was created using physiological data from 40 patients available in the literature, as well as 32 operating points from different bileaflet aortic valve prosthesis. A linear regression results in values around 14.0 kPa for the pressure gradient in the most severe case, evolving from 1.0 kPa for a healthy scenario. The thermodynamic model assesses the irreversibilities associated with energy conversion processes related to metabolism: exergy destroyed at the valves, exergy increased in the flow, and the power of the heart. Results indicate that destroyed exergy reaches values of 10 W (almost 10% of total basal metabolic rate of the whole body). Exergy efficiency is 15% for a healthy heart, decreasing as a function of the severity of the stenosis to values lower than 5%.

Tissue-engineered transcatheter vein valve

Chronic venous insufficiency affects over 2 million patients in the US alone, with severe cases involving thousands of patients with chronic leg ulcers and potential amputation. Current treatment options are limited, with surgical repair of vein valves being the most effective but challenging solution. A transcatheter vein valve made from a biologically-engineered matrix possessing the ability to regenerate has the potential to provide both valve function and long-term hemocompatibility and durability because the matrix becomes endothelialized and populated with host tissue cells. We have developed a novel tissue-engineered transcatheter vein valve (TEVV) on a Nitinol stent and demonstrated function and durability in vitro. Tissue was grown from fibroblasts in fibrin gel so as to embed the stent, with a tubular extension of the engineered tissue from one end of the stent that was stitched along opposite sides and everted into the stent to form a bileaflet valve. Following decellularization, to create an “off-the-shelf” TEVV comprised of the resulting collagenous matrix, it was tested in a pulse duplicator to evaluate hydrodynamic properties for a range of flow rates. The TEVV was shown to have forward pressure drops in the range of 2–4 mmHg, low closing volume, and nil regurgitation. Further hydrodynamic tests were performed after crimping and then again after 1 million cycle durability testing, showing no degradation of valve performance or any visual damage to the matrix. The TEVV held over 600 mmHg backpressure after the durability testing, ensuring the valve would withstand pressure spikes well outside of the normal in vivo range. Catheter-based delivery into the ovine iliac vein demonstrated TEVV closing 2 weeks p.o. and endothelialization without thrombosis 8 weeks p.o.

Tomographic PIV in a model of the left ventricle: 3D flow past biological and mechanical heart valves

Left ventricular flow is intrinsically complex, three-dimensional and unsteady. Its features are susceptible to cardiovascular pathology and treatment, in particular to surgical interventions involving the valves (mitral valve replacement). To improve our understanding of intraventricular fluid mechanics and the impact of various types of prosthetic valves thereon, we have developed a custom-designed versatile left ventricular phantom with anatomically realistic moving left ventricular membrane. A biological, a tilting disc and a bileaflet valve (in two different orientations) were mounted in the mitral position and tested under the same settings. To investigate 3D flow within the phantom, a four-view tomographic particle image velocimetry setup has been implemented. The results compare side-by-side the evolution of the 3D flow topology, vortical structures and kinetic energy in the left ventricle domain during the cardiac cycle. Except for the tilting disc valve, all tested prosthetic valves induced a crossed flow path, where the outflow crosses the inflow path, passing under the mitral valve. The biological valve shows a strong jet with a peak velocity about twice as high compared to all mechanical heart valves, which makes it easier to penetrate deeply into the cavity. Accordingly, the peak kinetic energy in the left ventricle in case of the biological valve is about four times higher than the mechanical heart valves. We conclude that the tomographic particle imaging velocimetry setup provides a useful ground truth measurement of flow features and allows a comparison of the effects of different valve types on left ventricular flow patterns.

Early Prosthetic Valve Malfunction Leading to Cardiogenic Shock and Emergency Redo Mitral Valve Replacement

Early onset prosthetic valve stenosis is an uncommon complication after valve replacement surgery and is often caused by thrombus formation. Frequently it can be diagnosed by echocardiography and managed with optimizing anticoagulation and/or thrombolysis. We review a unique case of early bi-leaflet mechanical heart valve (BMHV) dysfunction where the patient rapidly progressed to cardiogenic shock requiring emergent re-do mitral valve surgery. Intraoperatively, the valve leaflets were found to be almost completely immobile secondary to thrombus formation directly on the hinges of the valve. This case demonstrates how the leaflet orientation of a BMHV affects transmitral flow and fluid dynamics. Furthermore, we also discuss left atrial vortex formation in the setting of atrial fibrillation, kinetic energy transfer through an anatomically implanted mechanical mitral valve, and their roles in contributing to early prosthetic valve thrombosis despite adequate anticoagulation.

Assessing the Thrombogenic Potential of Heart Valve Prostheses: An Approach for a Standardized In-Vitro Method.

Thrombogenic complications are still a main issue in the general performance of cardiovascular implants, especially heart valves. To date, the thrombogenic potential of those prostheses is pre-clinically assessed in time consuming animal studies with questionable evidence. In this study, we present a new in-vitro method to assess and compare deficiencies of heart valve substitutes concerning their thrombogenic performance and locate initial clot formation under physiological conditions using porcine blood. Therefore, an athrombogenic pulse duplicator (THIA3) was developed that simulates the anatomic and hemodynamic conditions in the vicinity of the aortic valve. Validation of this tester was carried out with regard to hemodynamics, reproducibility and using positive and negative control valves and by comparison of clot locations with literature data from chronic animal trials with sheep using a St. Jude bileaflet valve. Validation of the tester showed quasi-physiological hemodynamics and reproducible clot formation. Identical clot formations were found comparing findings in vitro with chronic animal trials. The THIA 3 has proven its suitability for valid, reproducible evaluation of thrombogenic potential of heart valves in a short period of time.

Mitral Valve Prosthesis Design Affects Hemodynamic Stasis and Shear In The Dilated Left Ventricle.

Dilated cardiomyopathy produces abnormal left ventricular (LV) blood flow patterns that are linked with thromboembolism (TE). We hypothesized that implantation of mechanical heart valves non-trivially influences TE risk in these patients, exacerbating abnormal LV flow dynamics. The goal of this study was to assess how mitral valve design impacts flow and hemodynamic factors associated with TE. The mid-plane velocity field of a silicone dilated LV model was measured in a mock cardiovascular loop for three different mitral prostheses, two with multiple orientations, and used to characterize LV vortex properties through the cardiac cycle. Blood residence time and a platelet shear activation potential index (SAP) based on the cumulative exposure to shear were also computed. The porcine bioprosthesis (BP) and the bileaflet valve in the anti-anatomical (BL-AA) position produced the most natural flow patterns. The bileaflet valves experienced large shear in the valve hinges and recirculating shear-activated flow, especially in the anatomical (BL-A) and 45-degree (BL-45) positions, thus exhibited high SAP. The tilting disk valve in the septal orientation (TD-S) produced a complete reversal of flow and vortex properties, impairing LV washout and retaining shear-activated fluid, leading to the highest residence time and SAP. In contrast, the tilting disk valve in the free-wall position (TD-F) exhibited mid-range values for residence time and SAP. Hence, the thrombogenic potential of different MHV models and configurations can be collectively ranked from lowest to highest as: BP, BL-AA, TD-F, BL-A, BL-45, and TD-S. These findings provide new insight about the effect of fluid dynamics on LV TE risk, and suggest that the bioprosthesis valve in the mitral position minimizes this risk by producing more physiological flow patterns in patients with dilated cardiomyopathy.

Numerical and in-vitro experimental assessment of the performance of a novel designed expanded-polytetrafluoroethylene stentless bi-leaflet valve for aortic valve replacement.

The expanded polytetrafluoroethylene (ePTFE) heart valve can serve as a viable option for prosthetic aortic valve. In this study, an ePTFE bi-leaflet valve design for aortic valve replacement (AVR) is presented, and the performance of the proposed valve was assessed numerically and experimentally. The valve was designed using CAE software. The dynamic behavior of the newly designed bi-leaflet valve under time-varying physiological pressure loading was first investigated by using commercial finite element code. Then, in-vitro tests were performed to validate the simulation and to assess the hemodynamic performance of the proposed design. A tri-leaflet ePTFE valve was tested in-vitro under the same conditions as a reference. The maximum leaflet coaptation area of the bi-leaflet valve during diastole was 216.3 mm2. When fully closed, no leakage gap was observed and the free edges of the molded valve formed S-shaped lines. The maximum Von Mises stress during a full cardiac cycle was 4.20 MPa. The dynamic performance of the bi-leaflet valve was validated by the in-vitro test under physiological aortic pressure pulse. The effective orifice area (EOA), mean pressure gradient, regurgitant volume, leakage volume and energy loss of the proposed valve were 3.14 cm2, 8.74 mmHg, 5.93 ml/beat, 1.55 ml/beat and 98.99 mJ, respectively. This study reports a novel bi-leaflet valve design for AVR. The performance of the proposed valve was numerically and experimentally assessed. Compared with the reference valve, the proposed design exhibited better structural and hemodynamic performances, which improved valve competency. Moreover, the performance of the bi-leaflet design is comparable to commercialized valves available on the market. The results of the present study provide a viable option for the future clinical applications.

Utility of Cardiac CT for Preoperative Evaluation of Mitral Regurgitation: Morphological Evaluation of Mitral Valve and Prediction of Valve Replacement

ObjectiveWe aimed to investigate the diagnostic accuracy of cardiac computed tomography (CT) for the detection of mitral valve (MV) prolapse in mitral regurgitation (MR) with surgical findings as the standard reference, and to assess the predictability of MV replacement based on morphologic CT findings.Materials and MethodsA total of 156 patients who had undergone preoperative cardiac CT and subsequently received MV surgery due to severe MR were retrospectively enrolled. Non-repairable MV was defined when at least one of the following conditions was met: 1) anterior leaflet prolapse, 2) bi-leaflet prolapse, or 3) valve morphology (leaflet thickening, calcification, or mitral annular calcification [MAC]). Diagnostic performance of CT for the detection of the prolapsed segment was assessed with surgical findings as the standard reference. Logistic regression analysis was performed to evaluate the value of CT findings to predict actual valve replacement.ResultsDuring surgery, MV prolapse was identified in 72.1%. The sensitivity, specificity, and diagnostic accuracy for the detection of MV prolapse were 99.1%, 81.4%, and 94.2%, respectively, per patient. One-hundred eighteen patients (75.6%) underwent MV repair and the remaining 38 patients received MV replacement. Bi-leaflet prolapse and valve morphology were independent predictors of valve replacement after adjusting for clinical variables (adjusted odds ratio, [OR] 8.63 for bi-leaflet prolapse; OR, 4.14 for leaflet thickening; and OR, 5.37 for leaflet calcium score > 5.6; p < 0.05).ConclusionCardiac CT can have high diagnostic performance for detecting the prolapsed segment of the MV and predictability of valve replacement before surgery. Bi-leaflet prolapse and valve morphology, such as leaflet thickening, or calcification or MAC, are the most important predictors of valve replacement.

Large thrombus on a prosthetic aortic valve diagnosed on the 1stpostpartum day

40 years old female with prosthesis aortic valve had developed shortness of breath and consulted to our clinic on the first postpartum day. Her dyspnea was worsened at the last week. She had a history of Bentall operation before 16 years ago, and had a bi-leaflet mechanical prosthetic valve. After detection of pregnancy, her warfarin treatment had switched to enoxaparine 6000 IU subcutaneously for twice a day, continued throughout the pregnancy. Her weight was 62 kg. She did not have any blood test for factor Xa. On physical examination, she has orthopnea, tachypnea (24/min), tachycardia (128 bpm) and hypotension (85/55 mmHg). Electrocardiogram was uneventful with sinus tachycardia of 128 bpm with normal axis. Echocardiography revealed normal left ventricle size with left ventricle hypertrophy, ejection fraction of 60%, reduced motion of prosthetic-valve leaflets and an obstructing mass between the struts. Doppler ultrasonography showed that prosthetic aortic valve has a pressure gradient of 104/59 mmHg. These findings were consistent with prosthetic thrombosis. Moderate aortic regurgitation into the left ventricle was also detected. Transesophageal echocardiography showed 1.4 × 2.3 cm thrombotic material located over leaflets and adjacent to the posterior aortic wall. It was restricting the valve motion. The patient underwent emergency operation immediately. The thrombotic material over mechanical valve was extracted and there was no pathology seen on mechanical valve, graft repaired primarily. Postoperative recovery was fine. No bacteria were detected both direct microscopy and culture.

A novel trileaflet mechanical heart valve: first in vitro results.

Heart valve prostheses are the therapy of choice for patients with severe heart valve diseases. Two types of prostheses that can be implanted in patients are available: biological and mechanical. Though mechanical heart valves have some disadvantages like necessity of life-long anticoagulation, biological heart valve prostheses often necessitate reinterventions due to limited durability. Therefore, a new trileaflet mechanical heart valve was developed, featuring hinges in the systolic flow with the aim of function and thrombogenicity. We first compared the new trileaflet mechanical heart valve to conventional bileaflet heart valves (St. Jude Medical and On-X valves) in vitro. Haemodynamic measurements were performed in a pulse duplicator system, and clot formation was examined with an implemented method using enzyme-activated milk as the test medium. Haemodynamic measurements showed the largest effective orifice areas and smallest pressure gradients for the trileaflet prosthesis compared to the bileaflet valve. Opening and closing characteristics of the trileaflet valve and of the St. Jude Medical valve were comparable. Clotting tests depicted only minor isolated deposits for the new trileaflet valve whereas the bileaflet valves showed distinct clots in the area of the hinge in all experiments. Haemodynamic and clotting tests showed improvements for the new trileaflet valve compared to common bileaflet valves. The off-wall systolic position of the hinges, which eluded adverse flow areas, was a major advantage of the new valve.

Reduction of Pressure Gradient and Turbulence Using Vortex Generators in Prosthetic Heart Valves.

Blood damage and platelet activation are inherent problems with present day bi-leaflet mechanical heart valve designs. Passive flow control through different arrangements of vortex generators (VG) as means of improving pressure gradients and reducing turbulence are investigated. Rectangular VG arrays were mounted on the downstream surfaces of a 23mm 3D printed mechanical valve. The effect of VGs on the resulting flow structures were assessed under pulsatile physiological flow conditions where high resolution particle image velocimetry measurement was performed. The co-rotating VGs showed lower Reynolds shear stresses and improved pressure gradients (PG) compared with the counter-rotating ones and the no-VG control one (that showed higher turbulence). RSS was found 38.13 ± 0.89, 12.95 ± 0.32, 15.75 ± 0.71, 24.54 ± 0.84 and 16.33 ± 0.58Pa for the control, co-rotating VGs, 8 counter-rotating VGs, 4 far-spaced VGs and 4 closely-spaced VGs, respectively. PG of 10.45 ± 0.94mmHg was obtained with co-rotating VGs and the difference was significant compared with the other configurations (control 14.88 ± 0.4mmHg; 8 counter-rotating VGs 13.76 ± 0.51mmHg; 4 far-spaced VGs 13.84 ± 0.09mmHg; and 4 closely-spaced VGs 15.37 ± 0.16mmHg). Co-rotating VGs for this application induce a more delayed flow separation and a more homogenized and streamlined transition of flow compared with the counter-rotating VGs. Passive flow control techniques deployed on BHMVs is potentially beneficial as significant control of flow at small length scales without inducing large-scale design modifications of the valve.