Prosthetic Heart Valve Replacement Research Articles

A Fibrin-Thrombin Based In Vitro Perfusion System to Study Flow-Related Prosthetic Heart Valves Thrombosis

Prosthetic heart valve (PHV) replacement has increased the survival rate and quality of life for heart valve-diseased patients. However, PHV thrombosis remains a critical problem associated with these procedures. To better understand the PHV flow-related thrombosis problem, appropriate experimental models need to be developed. In this study, we present an in vitro fibrin clot model that mimics clot accumulation in PHVs under relevant hydrodynamic conditions while allowing real-time imaging. We created 3D-printed mechanical aortic valve models that were inserted into a transparent glass aorta model and connected to a system that simulates human aortic flow pulse and pressures. Thrombin was gradually injected into a circulating fibrinogen solution to induce fibrin clot formation, and clot accumulation was quantified via image analysis. The results of valves positioned in a normal versus a tilted configuration showed that clot accumulation correlated with the local flow features and was mainly present in areas of low shear and high residence time, where recirculating flows are dominant, as supported by computational fluid dynamic simulations. Overall, our work suggests that the developed method may provide data on flow-related clot accumulation in PHVs and may contribute to exploring new approaches and valve designs to reduce valve thrombosis.

Assessment of Machine Learning Approaches to Predict in-Hospital Mortality in Patients Underwent Prosthetic Heart Valve Replacement Surgery

Assessment of Machine Learning Approaches to Predict in-Hospital Mortality in Patients Underwent Prosthetic Heart Valve Replacement Surgery

Quantifying the Immune Response to a Tissue-Engineered Porcine Extracellular Matrix

Aim: Structural valvular deterioration of xenogenic heart valve replacements is thought to be due to a chronic immune response. We sought to engineer porcine extracellular matrixthat elicits minimal inflammatory immune response. Materials & methods: Whole blood, bone marrowand pericardium were collected from patients undergoing elective cardiac surgery. Porcine extracellular matrix was decellularized, reseeded with homologous mesenchymal stem cellsand exposed to whole blood. Results: DAPI stain confirmed the absence of cells after decellularization, and presence of mesenchymal stem cells after recellularization. There was a significant reduction in IL-1β and TNF-α production in the recellularized matrix. Conclusion: Recellularization of porcine matrix is successful at attenuating the xenogenic immune response and may provide a suitable scaffold to address the current limitations of prosthetic heart valve replacements.

Lessons Learned From Intermittent Dysfunction of Mechanical Heart Valve.

Background:Intermittent malfunction is a rare but potentially serious complication of prosthetic heart valve replacement. This study aimed to describe the clinical features and etiologic causes of patients with intermittent mechanical prosthetic heart valve dysfunction.Methods:Between 2010 and 2021, 16 patients who were evaluated in the echocardiography laboratory of Koşuyolu Training and Research Hospital with the diagnosis of intermittent malfunction of prosthetic valves were included in the study.Results:The evaluated patients consisted of 12 bi-leaflet mitral valve replacements and 2 mono-leaflet mitral valve replacements. The underlying causes of intermittent malfunction were classified as follows: residual chord (n = 4), obstructive thrombus (n = 2), non-obstructive thrombus (n = 2), vegetation (n = 2), pannus and obstructive thrombus coexistence (n = 1), and solely pannus (n = 1). One of the patients with mono-leaflet mitral valve replacements had pannus and obstructive thrombus. In the other patient with mono-leaflet mitral valve replacement, a stuck valve was observed in 1 of 12 beats secondary to arrhythmia. There were also 2 patients with aortic valve replacements. One patient had moderate aortic regurgitation due to prominent calcification and the other had moderate obstruction due to pannus. In the patient with pannus, a stuck leaflet was observed in 1 of 6 beats and moderate aortic regurgitation arose in 1 of 2 beats in the patient with calcification.Conclusions:The intermittent stuck valve may have catastrophic outcomes. When making a treatment decision in these patients, assessing the degree of regurgitation or stenosis is essential. In particular, the frequency of entrapment should be taken into consideration when deciding the optimal therapy for intermittent prosthetic heart valve dysfunction.

Thrombolysis or Surgery in Patients With Obstructive Mechanical Valve Thrombosis: The Multicenter HATTUSHA Study

BackgroundProsthetic valve thrombosis (PVT) is one of the life-threatening complications of prosthetic heart valve replacement. Due to the lack of randomized controlled trials, the optimal treatment of PVT remains controversial between thrombolytic therapy (TT) and surgery. ObjectivesThis study aimed to prospectively evaluate the outcomes of TT and surgery as the first-line treatment strategy in patients with obstructive PVT. MethodsA total of 158 obstructive PVT patients (women: 103 [65.2%]; median age 49 years [IQR: 39-60 years]) were enrolled in this multicenter observational prospective study. TT was performed using slow (6 hours) and/or ultraslow (25 hours) infusion of low-dose tissue plasminogen activator (t-PA) (25 mg) mostly in repeated sessions. The primary endpoint of the study was 3-month mortality following TT or surgery. ResultsThe initial management strategy was TT in 83 (52.5%) patients and surgery in 75 (47.5%) cases. The success rate of TT was 90.4% with a median t-PA dose of 59 mg (IQR: 37.5-100 mg). The incidences of outcomes in surgery and TT groups were as follows: minor complications (29 [38.7%] and 7 [8.4%], respectively), major complications (31 [41.3%] and 5 [6%], respectively), and the 3-month mortality rate (14 [18.7%] and 2 [2.4%], respectively). ConclusionsLow-dose and slow/ultraslow infusion of t-PA were associated with low complications and mortality and high success rates and should be considered as a viable treatment in patients with obstructive PVT.

The efficacy and safety of thrombolytic agents for patients with prosthetic valve thrombosis

Introduction: Prosthetic valve thrombosis (PVT) is a serious complication seen with mechanical prosthetic cardiac valves and is associated with high mortality. Emergency surgery (thrombectomy or valve replacement) had been the traditional treatment, but now with intravenous thrombolytic therapy as an alternative to emergency surgery in patients with PVT has shown excellent success rate and acceptable risk. This study is aimed to determine efficacy and safety of use of thrombolytic agents (tPA or STK) in patients with PVT. Materials and Methods: This was a retrospective, single-center study of patients with PVT admitted between 2004 and 2020 at a tertiary care center in North India. The diagnosis of PVT was based on a history of prosthetic heart valve replacement, clinical presentation, and by diagnostic methods. All patients received either tenecteplase or streptokinase given as a bolus dose of 2.5 lac units over ½ h, followed by 1 lac units/h for 24–48 h depending on clinical response and complication, whereas tenecteplase (1 mg/kg of body weight) was given as bolus. Results: Of 72 patients, 45 patients received t-PA as a thrombolytic drug. Complete success was obtained in 39 patients (86.66%), whereas partial success in 3 (17.77%) and failure in 3 (6.66%). Among the patients who received streptokinase (n = 27), complete success was found in 23 patients (85.19%), whereas partial success was seen in 3 (11.11%) and failure was seen in 1 patient (3.7%). Conclusion: Thrombolysis is a reasonable option in patients with PVT. Our study has reiterated that major factors for PVT are warfarin poor compliance and subtherapeutic international normalized ratio. Postclosure clinical follow-up along with patient education should be followed in patients with mechanical prosthetic valve.

Optimal International Normalized Ratio Range for Asian Patients on Anticoagulation Therapy

Introduction: Despite the recent emergence of direct oral anticoagulants, the use of warfarin will continue in patients on warfarin with stable control, those with mechanical heart valves, antiphospholipid syndrome and significant renal impairment. Warfarin therapy is challenging because of its narrow therapeutic window. The aim is to administer the lowest effective dose to maintain the target International Normalized Ratio (INR) in order to minimize bleeding and thromboembolic complications. The optimal INR of 2.0-3.0 has been validated in Western populations but not in Asians. It is common belief that Asians on warfarin having more bleeding complications and results of retrospective small scale studies conducted in Asian populations suggested a lower therapeutic INR range. Hence a lower target INRs had been advocated.1Objective: To determine the optimal INR range associated with the lowest thromboembolism and bleeding rates for a large multi-ethnic Asian population receiving warfarin therapy in Singapore.Methods:A retrospective cohort study was conducted among adult patients receiving warfarin from Singapore General Hospital and National Heart Centre Singapore, between 1 January 2010 and 31 December 2014. These patients were closely followed up with tight reporting and recording of adverse events. Medical records from clinics, hospitalisation and emergency room visits in both centres were analysed for warfarin-related thromboembolism and bleeding events and INR values at time of events. Thromboembolic events included ischemic stroke, deep vein thrombosis (DVT) and pulmonary embolism (PE). Bleeding events were differentiated into major and minor bleeds according to the International Society on Thrombosis and Haemostasis criteria.Results: A total of 1216 patients (650 males, 566 females) with 12,784 patient-years were included in the study. Racial distribution was 79.2 % Chinese, 12.6% Malays, 6.6% Indians and 1.6% others. 89.2% of the patients were above 50 years old, with 48.8% aged between 51 to 70 years and 40.3 % aged between 71 to 100 years. Indications for warfarin were atrial fibrillation (57.3%), prosthetic heart valve replacement (16.9%), intracardiac thrombus (5.4%), venous thromboembolism (16.6%), ischaemic strokes (1.6%), rheumatic heart disease (1.4%) and others (0.8%).There were 1776 thromboembolic and bleeding events. The event rates were 2.7 per 100 patient-years for major bleeds, 3.8 per 100 patient-years for thromboembolic events and 7.4 per 100 patient-years for minor bleeds. Using the Poisson Regression analysis, the INR range of 2.01-2.60 was found to correspond with a lowest combined major bleeding and thromboembolism risk of 2.9% (figure 1). When analysed to obtained a bootstrapped (n=1,000) estimate of the rate of events by 1-unit INR ranges, given a usual “good” time in target range of 60% achieved by our anticoagulation clinic, we found that the 2.0-3.0 INR range had the minimum rate of major bleed and thromboembolism events (figure 2), accounting for uncertainty in actual INR values at adverse events. This finding is likely to be further reinforced if one accounts for uncertainty in the actual rate of events by INR range.Conclusion:The major bleeding rate of 2.7 per 100 patient years in this Asian population is consistent and not higher than reports in recent western population cohort studies2,3.The optimal INR range for Asian patients on anticoagulation therapy in Singapore was 2.01-2.60 by the Poisson Regression analysis. However, such a narrow target INR range will be challenging to implement in practice. Except for those at extreme risks of bleeding or thrombosis, the data from our bootstrapped analysis supports the use of the recommended INR range of 2-3 for Asians. Thus while Asians may have an increased sensitivity to warfarin in requiring lower dosages, the target therapeutic INR range of 2-3 remains.

Maternal and fetal outcomes in pregnant females with rheumatic heart disease

BackgroundCardiac diseases are seen in 1–3% of pregnancies. In developing countries rheumatic heart disease (RHD) contributes a major cause of cardiac disorders. ObjectiveTo study the maternal and fetal outcome in women with valvular heart disease or prosthetic heart valve replacement secondary to RHD in a tertiary care center. MethodThe consecutive pregnant women with RHD attending our institute from May 2018 to August 2019 were included. A maternal adverse outcome was defined as cardiac death, new onset arrhythmia, heart failure, thromboembolic event, hospitalization for other cardiac reasons or cardiac intervention, aortic dissection, infective endocarditis and acute coronary syndrome. Fetal adverse outcome defined as fetal death, preterm birth, and low birth weight. ResultTotal 80 patients were included in this study, native RHD in 60(75%) and 20(25%) had mechanical prosthetic valve replacement. Maternal adverse event occurred in 34(42.5%), comprising of death in 1(1.2%), new onset AF 2(2.5%), 20(25%) underwent balloon mitral valvotomy, 3(3.7%) underwent mitral valve replacement, heart failure hospitalization in 7(8.7%). 1(1.2%) patient developed mitral valve infective endocarditis. Preterm delivery occurred in 19(23.7%), 7(8.7%) abortions and 1(1.2%) intrauterine death. Fetuses with low birth weight were 43(53.7%). Pregnancy with live birth occurred in 57(95%) women with valvular heart disease but no prosthesis and 16(80%) women with prosthetic valve disease. ConclusionWomen with rheumatic heart disease carry a high risk both for mother and fetus. Early diagnosis, close follow-up during pregnancy, early recognition of deterioration in symptoms and timely cardiac intervention can lead to good maternal or fetal outcome.

Comparative Surgical Outcomes of Prosthetic and Native Valve Endocarditis.

As a consequence of a growing number of patients undergoing prosthetic heart valve replacement, the incidence of prosthetic valve endocarditis (PVE) has increased. The study aims to analyze patterns and outcomes of PVE surgery as compared with native valve endocarditis (NVE). We enrolled 269 patients (aged 58.0±15.7 years) who underwent valve surgery for infective endocarditis (IE) between 2013 and 2019. Of these, 56 had PVE whereas remainder (n=213) had NVE. Clinical outcomes were compared and multivariable analyses were conducted to determine risk factors for mortality. The proportion of PVE among surgical IE gradually increased from 15.4% (11/71) in the first time-quartile to 29.5% (18/61) in the last time-quartile (p=0.055). PVE patients were older, and more commonly had aorto-mitral curtain involvement and abscess formation than NVE group. Early mortality was 14.3% and 6.1% in PVE and NVE group, respectively (p=0.049). Postoperatively, PVE group had higher incidences of low cardiac output syndrome (p=0.027), new-onset dialysis (p=0.006) and reoperation for bleeding (p=0.004) compared to NVE group, but stroke rates were comparable (p=0.503). During follow-up (648.8 patient-years), PVE group showed significantly higher risks of overall mortality (p<0.001), valve reinfection (p<0.001) and permanent pacemaker implantation (p<0.001) than NVE group. On multivariable analysis, PVE (hazard ratio, 2.67; 95% confidence interval, 1.40-5.07; p=0.003) along with age, chronic kidney disease, multi-valve involvement, and causative organisms of Staphylococcus aureus or fungus were independent risk factors of overall mortality. PVE carried significant perioperative risks, and was an independent risk factor of overall mortality.

Anticoagulation and antiplatelet therapy in patients with prosthetic heart valves.

The choice of antithrombotic therapy, anticoagulants or antiplatelets, after prosthetic heart valve replacement or repair, remains a disputed topic in the literature. Antithrombotic therapies are used after heart valve intervention to reduce the rates of thromboembolic events, therefore improving patient outcomes. Different interventions may require different therapeutic regimens to achieve the most efficacious clinical outcome for patients. This review aims to summarize and critique the available literature concerning therapeutic agents used for bioprosthetic and mechanical valves as well as for valve repair, so as to assist clinicians and researchers in making decisions with regard to their patients and research endeavors.

Biodegradable synthetic polymeric composite scaffold‐based tissue engineered heart valve with minimally invasive transcatheter implantation

Prosthetic heart valve replacement is the main treatment for valvular heart disease, but the existing artificial valves (mechanical or biological valve) have inherent disadvantages. Patients with mechanical valves require lifelong anticoagulation because of the high risk of thromboembolism, while the durability of biological valve is poor, which easily leads to calcification or lobular degeneration. Besides, they all lack the abilities of self‐repair and growth which are very important for adolescent patients with valvular heart disease. To overcome these shortcomings, the researchers developed tissue engineered heart valves (TEHV) with self‐repairing and remodeling capabilities, low immunogenicity, and great durability. The preparation of three‐dimensional porous scaffolds is the key step in the success of TEHV. Because of their easy processing, active chemical properties, great mechanical properties and controllable degradation rate, synthetic biodegradable polymers are widely used in the preparation of TEHV scaffolds. This review summarizes the types, properties and process techniques of biodegradable synthetic polymers, such as polycaprolactone, polyglycolic acid, polylactic acid, and polyhydroxyalkanoates currently used to prepare the TEHV scaffolds. This review also focuses on the composite methods and performance of synthetic polymer‐based composite scaffolds. The prospects and challenges of the clinical application for minimally invasive implantation of TEHV are also discussed.

인공심장판막치환 환자의 와파린 관련 지식, 자기효능감 및 약물복용이행도의 관계

본 연구는 와파린 약물 관련 지식, 자기효능감, 약물복용이행도의 관계를 파악하여 와파린 약물복용이행도를 높일 수 있는 교육의 필요성을 강조하고 효율적인 맞춤형 간호중재 프로그램 개발에 도움이 되고자 시행하였다. 연구방법은 서술적 상관관계 연구로 2018년 2월 21일부터 9월 30일까지 20세 이상의 성인을 대상으로 심장판막 수술을 받고 와파린을 복용한지 6개월 이상 된 외래 통원치료 환자를 대상으로 이루어졌다. 연구결과 와파린 약물관련 지식과 약물복용이행도에서 유의한 상관관계(r=.285, p =.004)를 보였다. 70세 미만에서 약물복용이행도는 와파린 약물관련 지식(r=.250, p =.046)과 자기효능감(r=.292, p =.019)에서 각각 양의 상관관계를 보였고, 70세 이상에서 약물복용이행도는 와파린 약물관련 지식(r=.358, p =.032)과 유의한 양의 상관관계가 있었다. 또한 약물복용이행도의 차이에서 70세 미만 (7.24±1.30)과 70세 이상(7.09±1.00)에서 연령과 상관없이 큰 차이가 없었는데, 이는 고령화에도 불구하고 약물복용이행이 비슷한 수준으로 잘 유지된 것으로 볼 수 있어 어떤 요소가 70세 이상의 고령 환자의 약물복용이행도를 높게 유지하는 지 후속연구가 필요하겠다. 따라서 약물복용이행도를 향상시키기 위해서는 간호 교육 측면으로 1:1개별 교육 프로그램, 코칭 프로그램을 개발하고, 간호 연구 측면으로 각 분야의 다양한 전문가가 연계되어 와파린 복용 교육에 대한 연구가 필요하다. 또한 시각적 측면으로 약물 교육에 대한 멀티미디어 효과에 대한 연구를 제언한다.

Extracellular matrix coating improves the biocompatibility of polymeric heart valves.

Prosthetic heart valve replacement is an effective therapy for patients with valvular heart disease. New-type polymer materials provide potential choices of material for preparing prosthetic heart valves. In this study, we focused on enhancing the biocompatibility of polystyrene-block-isobutylene-block-styrene (SIBS) by surface modification with an extracellular matrix (ECM). Experimental results demonstrated that the ECM coating increased the adsorption resistance against protein and platelets. SIBS coated with an ECM adsorbed much less bovine serum albumin and fibrinogen (5.38 μg cm-2 and 31.53 μg cm-2, respectively) than the original material (90.84 μg cm-2 and 132.38 μg cm-2, respectively). The relative platelet adsorption of the ECM-modified SIBS was lower than that of SIBS (0.04 versus 0.10). Moreover, the surface coating could also reduce endothelial cytotoxicity, suppress the immune response, and potentially induce tissue regeneration. In conclusion, ECM coating improved the biocompatibility of SIBS effectively.

Oral Anticoagulant Therapy-When Art Meets Science.

Anticoagulant treatment is extremely important and frequently encountered in the therapy of various cardiovascular diseases. Vitamin K antagonists (VKA) are in use for the prevention and treatment of arterial and venous thromboembolism, despite the introduction of new direct-acting oral anticoagulants (NOAC). The VKA still have the clear recommendation in patients with a mechanical prosthetic heart valve replacement or moderate to severe mitral stenosis of the rheumatic origin, in deep vein thrombosis associated with congenital thrombophilia, and in cases where NOAC are prohibited by social condition (financial reason) or by comorbidities (extreme weight, severe renal or liver disease). VKA dosing required to reach the targeted therapeutic range varies largely between patients (inter-individual variability). This inter-individual variability depends on multiple environmental factors such as age, mass, diet, etc. but it is also influenced by genetic determinism. About 30 genes implicated in the metabolism coumarins derivatives were identified, the most important being CYP2C9 and VKORC, each with several polymorphisms. Herein, we review the data regarding genetic alterations in general and specific populations, highlight the diagnosis options in particular cases presenting with genetic alteration causing higher sensitivity and/or resistance to VKA therapy and underline the utility of NOAC in solving such rare and difficult problems.

Propensity Score Matched Analysis of Mechanical vs. Bioprosthetic Valve Replacement in Patients With Previous Stroke.

This study compared the long-term outcomes of prosthetic heart valve replacement with mechanical or bioprosthetic valves in patients with prior stroke.Methods and Results:In total, 1,984 patients with previous stroke who had received valve replacement between 2000 and 2011 were identified using the Taiwan National Health Insurance Research Database. Propensity score matching analysis was used. Ultimately, 547 patients were extracted from each group and were eligible for analysis. On survival analysis, the risks of all-cause mortality and recurrence of stroke were similar. The incidence of major bleeding was greater in the mechanical valve group than in the bioprosthetic valve group (P=0.040), whereas no difference was observed in re-do valve surgery. On subgroup analysis, the bioprosthetic valve was favored for older age (≥60 years) and previous gastrointestinal (GI) bleeding patients. The mechanical valve, however, was favored for younger patients (<60 years). In patients with previous stroke, bioprosthetic valves had a lower incidence of complications connected to major bleeding than did the mechanical valves. Survival and stroke recurrence rates, however, did not differ between the 2 groups. We recommend bioprosthetic valves for patients >60 years or who have a history of GI bleeding.

The additional role of 18F-FDG PET/CT in prosthetic valve endocarditis.

The purpose of the present review is an update on the diagnosis of prosthetic valve endocarditis (PVE), evaluating the additional value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) to the standard modified DUKE criteria on which for a long time is based the diagnostic strategy of the disease. We did a comprehensive research on the studies reported in the literature and regarding the employment of 18F-FDG PET/CT in the early diagnosis of PVE in patients with suspected disease. Scientific databases have been examined such as Medline and PubMed, followed by a review of citations and reference lists. The research included the following terms: infective endocarditis, prosthetic heart valve and cardiac valve replacement infections, 18F-FDG PET/CT and endocarditis. The recent studies reported in the literature on the PVE diagnostic approaches showed elevated sensitivity and specificity values of 18F-FDG PET/CT ranging from 73 to 96.6% and from 80 to 94%, respectively, reducing the number of misdiagnosed patients. The usefulness of the radioisotopic procedure is even more important when the other diagnostic conventional diagnostic tools, such as echocardiography, are inconclusive or negative in patients in whom the diagnosis of PVE is definitively ascertained. However, false negative and positive results of 18F-FDG PET/CT were also ascertained in some studies interfering with image interpretation even if such limitation can be reduced with an adequate patient preparation, with a better knowledge of clinical course of the disease, of the treatment in progress and of the different technical aspects of the method. In different studies reported in the literature, 18F-FDG PET/CT proved to improve the diagnostic accuracy of the conventional modified DUKE criteria in patients with suspected IE, and in particular with PVE, giving the highest diagnostic performance and providing additional diagnostic benefits. Thus, the radioisotopic hybrid procedure should be included in the diagnostic protocol of PVE as complementary tool to modified DUKE criteria. Finally, the usefulness of 18F-FDG PET/CT in monitoring the response to antibiotic therapy, although the few data reported in the literature are encouraging, needs more numerous studies and with a major number of cases.

A case of a woman with prosthetic mechanical heart valve replacement who suffered from a stuck valve during administration of heparin calcium self-injection at home

A case of a woman with prosthetic mechanical heart valve replacement who suffered from a stuck valve during administration of heparin calcium self-injection at home

Allograft Heart Valves: Current Aspects and Future Applications.

Human heart valve allografts continue to represent almost perfect substitutes for heart valves. They have optimal hemodynamic characteristics and are highly resistant to infections. The first clinical use of allograft heart valves was as homovitals being transplanted after antibiotic incubation without any preservation. Since 1968, relatively standardized frozen cryopreservation (SFC) has been employed, including storage in vapor-phase liquid nitrogen. Disadvantages, particularly in pediatric patients, are limited availability due to organ scarcity, inability to grow, degeneration, immune response, and long-term failure. However, in contrast to alternative prosthetic or bioprosthetic heart valve replacements, they represent the best pediatric and juvenile replacement options for the pulmonary valve. Application of multiphoton imaging analysis for three-dimensional visualization of elastin and collagen by induction of autofluorescence without chemical fixation, embedding, and staining has revealed partial destruction of elastic and collagenous matrix in SFC valves. As the overall amount of collagen and elastin remains unchanged, the observed destruction is attributed to freezing-induced extracellular matrix damages due to ice crystal formation during SFC. The objective of this review is an assessment of current allograft preservation methods and the potential of novel preservation techniques to avoid ice formation with accompanied better long-term function.

Optimum INR in patients with prosthetic heart valve replacement

Objective Despite various innovations, there is no ideal prosthetic heart valve; thus, patients with prosthetic heart valves still require anticoagulation therapy. This is a retrospective study to identify the optimum warfarin dose and international normalized ratio (INR) in Indian patients with prosthetic heart valves.

Obstetric history after mechanical cardiac valve replacement

In patients who have undergone mechanical prosthetic heart valve replacement, pregnancy is associated with the risks of warfarin embryopathy. A significant proportion of our patient undergoing mechanical mitral cardiac valve replacement were females of child bearing age.