Periprocedural Bridging Therapy in Patients With Mechanical Heart Valves

Mechanical heart valves (MHVs) are thrombogenic and require lifelong anticoagulation with vitamin K antagonists (VKAs) such as warfarin. Periprocedural bridging with unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) aims to reduce the risk of thromboembolic events in patients. Currently, there are no definitive class I recommendations for anticoagulation management in patients with MHVs. In this report, we present the case of a 77-year-old female who was perioperatively bridged with enoxaparin and subsequently developed an acute thrombus.

Clear and present danger: Mechanical heart valves in pregnancy

Specialists in Obstetric Haematology continue to be challenged by pregnant women with mechanical heart valves, who are at high risk of death or severe morbidity. Effective anticoagulation to reduce valve thrombosis inevitably increases risk of obstetric haemorrhage and fetal loss or harm, and difficult decisions need to be made. Lester and mulitdisciplinary colleagues on behalf of the British Society for Haematology review available evidence and provide comprehensive recommendations to guide management in this difficult area. Commentary on: Lester et al. British Society for Haematology guideline for anticoagulant management of pregnant individuals with mechanical heart valves. Br J Haematol 2023 (Online ahead of print). doi: https://doi.org/10.1111/bjh.18781.

Polymeric Heart Valves Will Displace Mechanical and Tissue Heart Valves: A New Era for the Medical Devices

The development of a novel artificial heart valve with outstanding durability and safety has remained a challenge since the first mechanical heart valve entered the market 65 years ago. Recent progress in high-molecular compounds opened new horizons in overcoming major drawbacks of mechanical and tissue heart valves (dysfunction and failure, tissue degradation, calcification, high immunogenic potential, and high risk of thrombosis), providing new insights into the development of an ideal artificial heart valve. Polymeric heart valves can best mimic the tissue-level mechanical behavior of the native valves. This review summarizes the evolution of polymeric heart valves and the state-of-the-art approaches to their development, fabrication, and manufacturing. The review discusses the biocompatibility and durability testing of previously investigated polymeric materials and presents the most recent developments, including the first human clinical trials of LifePolymer. New promising functional polymers, nanocomposite biomaterials, and valve designs are discussed in terms of their potential application in the development of an ideal polymeric heart valve. The superiority and inferiority of nanocomposite and hybrid materials to non-modified polymers are reported. The review proposes several concepts potentially suitable to address the above-mentioned challenges arising in the R&D of polymeric heart valves from the properties, structure, and surface of polymeric materials. Additive manufacturing, nanotechnology, anisotropy control, machine learning, and advanced modeling tools have given the green light to set new directions for polymeric heart valves.

Redefining the Roles of Aspirin across the Spectrum of Cardiovascular Disease Prevention

Even before its role in platelet inhibition was fully characterized in the 1980s, aspirin had been incorporated into the cardiovascular disease care algorithm. Early trials examining its use in unstable angina and acute myocardial infarction revealed evidence of its protective role in the secondary prevention of atherosclerotic cardiovascular disease (ASCVD). Large trials assessing use in the primary prevention setting and optimal dosing regimens were studied in the late 1990s and early 2000s. As a cornerstone of cardiovascular care, aspirin was incorporated into primary and secondary ASCVD prevention guidelines in the United States and mechanical heart valve guidelines. However, in recent years, with significant advances in medical and interventional ASCVD therapies, scrutiny has been placed on the bleeding profile of aspirin, and guidelines have adapted to new evidence. Updates in primary prevention guidelines reserve aspirin only for patients at higher ASCVD risk and low bleeding risk - though questions remain in ASCVD risk assessment as risk-enhancing factors have proven difficult to incorporate on a population level. New thoughts regarding aspirin use in secondary prevention - especially with the concomitant use of anticoagulants - have altered recommendations as additional data accrued. Finally, a recommendation for aspirin and vitamin K antagonists with mechanical heart valves has been modified. Despite aspirin losing a foothold in cardiovascular care, new evidence has strengthened claims for its use in women at high risk for preeclampsia.

Outcomes in Pregnant Women with Valvular Heart Disease from Portuguese-Speaking African Countries Treated in Portugal through an International Agreement of Health Cooperation

Aims

We performed a clinical audit of maternal and fetal outcomes in pregnant women with valvular heart disease (VHD) from Portuguese-speaking African countries who were transferred for their care, during a twenty-year period, through a memorandum of agreement of international cooperation.

Methods and results

A retrospective analysis of 81 pregnancies in 45 patients with VHD (median age 24, interquartile range 22-29 years) from 2000 to 2020 was performed. The main outcome measures were maternal cardiovascular and fetal outcomes. History of rheumatic heart disease was present in 60 (74.1%) pregnancies. Most were in New York Heart Association (NYHA) functional class I or II; at the first evaluation, 35 (43.2%) were on cardiac medication and 49 (60.5%) were anticoagulated. Forty-eight pregnancies had at least one valvular prosthesis, including 38 mechanical heart valves. During pregnancy, deterioration in NYHA functional class occurred in 35 (42.0%), and eight (9.9%) patients required initiation or intensified cardiac medication. Mechanical valve thrombosis complicated four (4.9%) pregnancies, all cases on heparin, and resulted in one maternal death. Haemorrhagic complications happened in 7 (8.6%) anticoagulated patients, in the immediate postpartum or puerperal period. The 81 pregnancies resulted in 56 (69.1%) live births, while miscarriage and fetal malformations occurred in 19 (23.5%) and 12 (14.8%) pregnancies, respectively. In multivariate analysis, vitamin K antagonist therapy was the only independent predictor of an unsuccessful pregnancy (p = 0.048).

Conclusion

In a high-income country, successful pregnancy was possible with low rate of maternal events in women with VHD transferred from five low-middle income countries in Africa. The use of anticoagulation with a vitamin K antagonist was associated with an unsuccessful pregnancy.

Anticoagulation for mechanical heart valves during pregnancy: A case report and a literature review

RATIONALE

Most previous treatment guidelines for pregnant women with mechanical heart valves recommend that low molecular weight heparin (LMWH) should be applied once every 12 hours and only as required to reach peak anti-Xa levels of approximately 1.0 to 1.2 IU/mL, but it is commonly associated with subtherapeutic trough levels, consequently with an inadequate level of anticoagulation. Our case report here together with a literature review suggests that dose-adjusted (Target trough anti-Xa levels of 0.6 to 0.7 IU/mL and with peak anti-Xa levels of around 1.0 to 1.2 IU/mL or < 1.5 IU/mL) LMWH should be given thrice daily throughout pregnancy. In addition, the findings of this rare case indicate that a combination of LMWH and warfarin is effective in the treatment of small thromboses in pregnancy.

PATIENT CONCERNS

In the 1st trimester of pregnancy, a 28-year old pregnant female with a mechanical valve had a significant increase in the aortic valve flow rate and suspected mechanical valve thrombosis.

DIAGNOSES

The peak velocity of the pregnant female aortic mechanical valve increased, and mechanical valve thrombosis was suspected.

INTERVENTIONS

We adjusted the enoxaparin sodium dose every 12 hours to 1 injection every 8 hours, with a total daily dose of 160 mL. Based on the original application of LMWH, warfarin (3 mg/day) was recommended.

OUTCOMES

The pregnant woman delivered a live baby by cesarean section, and the peak flow velocity of the mechanical valve in the aortic position was reduced to nearly equivalent to the patient's pre-pregnancy status. The mother and the baby were in good health at the time of discharge.

LESSONS

LMWH is administered twice daily, and anti-Xa trough levels are mostly in a subtherapeutic state, which may lead to insufficient anticoagulation and thrombosis. Dose-adjusted LMWH thrice daily throughout pregnancy is the recommended treatment for pregnant women with mechanical heart valves. The combination of LMWH and warfarin exhibited good efficacy for the treatment of small thromboses.

A clinical conundrum: review of anticoagulation in pregnant women with mechanical prosthetic heart valves

In South Africa, maternal mortality from cardiovascular disease remains high. The recent Saving Mothers report 2017-2019 from the Confidential Enquiries into Maternal Deaths revealed that indirect maternal death from medical and surgical disorders is the fourth commonest cause of maternal death, accounting for 16.9% of deaths, with cardiac disease accounting for one-third of this. The burden of rheumatic heart disease (RHD) is a significant contributor to maternal morbidity and mortality. The true burden is unknown due to limited data. The natural history of RHD confers additional risk as many cases may remain undiagnosed, with first presentation occurring during pregnancy. This undiagnosed subset of women may be the result of poor accessibility to healthcare facilities and primary healthcare interventions for acute rheumatic fever. RHD causes progressive damage to the heart valves, especially the left-sided valves, which eventually require surgical correction with mechanical prosthetic valves.

Society for Maternal-Fetal Medicine Consult Series #61: Anticoagulation in pregnant patients with cardiac disease

Pregnancy in individuals with a mechanical heart valve has been classified as very high risk because of a substantially increased risk of maternal mortality or severe morbidity. Lifelong therapeutic anticoagulation is a principal component of the medical management of mechanical heart valves to prevent valve thrombosis. Anticoagulation regimens indicated outside of pregnancy for patients with mechanical valves should be continued during pregnancy with the possibility of modifications based on the type of valve, the trimester of pregnancy, individual risk tolerance, and circumstances around the time of delivery. The purpose of this document is to provide recommendations regarding the management of anticoagulation for common cardiac conditions complicating pregnancy, including mechanical heart valves, atrial fibrillation, systolic heart failure, and congenital heart disease.

Pregnancy Outcomes in Women With Mechanical Valve Prostheses Using Vitamin K Antagonist Therapy: The Experience of the Salam Centre for Cardiac Surgery in Sudan

Pregnancy and childbirth on anticoagulants after mechanical heart valve replacement present a high risk of complications for both mother and baby. On top of pregnancy worsening the mother's cardiac function, anticoagulant therapy itself is a crucial problem. A safe and effective anticoagulation regimen for both mother and fetus is not possible. The most effective drugs for preventing valve thrombosis are VKAs, whose dosage needs to be adjusted with frequent INR checks. Moreover, VKAs can have embryopathic and teratogenic action. Patients in follow-up and anticoagulant treatment at the Salam Centre for Cardiac Surgery in Sudan live spread out over a large area where transport to the Center is generally difficult; pregnancy treatment has, therefore, been adapted to the limitations of reality. Pregnancy is discouraged and contraception and therapeutic abortion are recommended, but this guidance frequently goes unheeded. Here we describe maternal and fetal outcomes in 307 consecutive pregnancies recorded by staff at the oral anticoagulant clinic (OAC) from April 2017 to November 2021. Out of 307 pregnancies, there were 15 maternal deaths (4.9%), 24 thrombotic events (7.8%) and 22 major bleedings (7.2%). Fifty pregnancies (16.3%) were terminated by therapeutic abortion. Only 47.6% of pregnancies had good maternal and neonatal outcomes. Data clearly show that, due to the complexity of pregnancy in women with mechanical heart valves and the scarcity of tertiary healthcare services in the area where patients live, maternal mortality is at an unacceptable level and requires a structured, multi-disciplinary intervention.

Anticoagulation in pregnant women with mechanical heart valve prostheses: Case reports and a literature review

The choice and regimen of anticoagulation therapy in pregnant women with mechanical valve prostheses have always been a daunting task. It is a delicate balance that takes into consideration the risk of thromboembolic complications in the mother and the risk of potential Warfarin embryopathy to the foetus. Medical practice in a low socioeconomic setting also has the peculiar challenge of financial constraints on the part of the patients and difficulties in monitoring the efficacy of anticoagulation therapy. We report our experience in managing two pregnant women with mechanical valve prostheses and review the existing literature on this complex but interesting subject.

Khat Chewing Effect on the International Normalized Ratio in Patients with Mechanical Heart Valves under Warfarin Therapy

BACKGROUND AND OBJECTIVE

Khat is a plant that contains the alkaloids cathine and cathinone which have some amphetamine-like properties. It is cultivated and it's leaves chewed for their euphoric effect. This study intended to elucidate the effect of khat chewing on blood coagulation by using the International Normalized Ratio (INR) value as a calculable benchmark.

MATERIALS AND METHODS

In this cohort study, 146 patients with Mechanical Heart Valves (MHV) were assessed for two consecutive visits at one-month intervals. For each visit, the date of surgery, the patient's compliance, the dose of warfarin and the INR reading were assessed by the researcher.

RESULTS

Out of 146 patients with MHV, the mean age was 33.72±12.43 years (range, 14-65 years); 82 (56.2%) were female and 64 (43.8%) were male. The results revealed that the mean of absolute INR readings was lower in khat-chewers than non-chewers by average 0.2 on the first and second visits (p = 0.038 and 0.002, respectively).

CONCLUSION

Khat chewing has a significant coagulant effect. There was a significant decrease in the value of INR for khat chewers patients with MHV when compared to non-khat chewers.

A case series of patients with left ventricular assist devices and concomitant mechanical heart valves

Mechanical heart valves left in situ at the time of left ventricular assist device (LVAD) implantation are thought to potentially increase the risk of thromboembolism. Recommendations exist to replace dysfunctional mechanical mitral valves and any mechanical aortic valves at the time of LVAD implantation. Due to potential increases in cardiopulmonary bypass time and associated comorbidities with valve replacement, leaving a functional mechanical valve in place at LVAD implantation has been suggested to be a safe option. We retrospectively reviewed all patients with prior mechanical mitral or aortic valves undergoing LVAD implantation at our center between 2012 and 2017. Echocardiograms were read by a single cardiologist to assess for mechanical valve dysfunction. We identified 15 patients. Five patients had major bleeding requiring transfusion. On follow-up, 2 patients had hemorrhagic stroke and 2 had transient ischemic attach/ischemic stroke. In addition, 2 patients had LVAD thrombosis and 2 patients had LVAD driveline malfunction. Mild mechanical valve regurgitation was identified on follow-up echocardiograms of 2 patients. Rate of complications in patients with mechanical valves undergoing LVAD implantation was comparable to that reported for the general LVAD population. Leaving a functional mechanical valve in place at the time of LVAD implantation could be a reasonable alternative to valve replacement. More data are required to further guide patient care in these individuals.

Anticoagulation regimens during pregnancy in patients with mechanical heart valves: a protocol for a systematic review and network meta-analysis

INTRODUCTION

Pregnancy in patients with mechanical heart valves (MHVs) is associated with high maternal complications and fetal complications.Anticoagulation treatments serve to decrease their venous clotting risk. Although some anticoagulation regimens have been used for patients during pregnancy with MHVs, no one is definitively superior among different regimens in recent studies. For a better understanding of the clinical treatment which anticoagulation regimen is more effective and safer during the pregnancy in patients with MHVs, a Bayesian network meta-analysis is necessary.

METHODS AND ANALYSIS

This protocol has been reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols. Related studies until April 2019 will be searched in the following databases: PubMed, Embase,SinoMed and the using the OVID interface to search for evidence-based medicine reviews. A clinical trial registry (www.ClinicalTrials.gov) was also searched for unpublished trials. Both experimental studies (randomised clinical trials) and observational studies (cohort studies, case-control studies and case series studies) will be included in this study. Quality assessment will be conducted using Cochrane Collaboration's tool or Newcastle-Ottawa Scale based on their study designs. The primary outcomes of interest will be the frequencies of serious maternal and fetal events. The additional outcomes of interest will be adverse maternal events, mode of delivery and adverse fetal events. Pairwise and network meta-analysis will be conducted using R (V.3.4.4, R Foundation for Statistical Computing, Vienna, Austria) and Stata (V.14, StataCorp). The ranking probabilities will be estimated at each possible rank for each anticoagulation regimen using the surface under the cumulative ranking curve. Statistical inconsistency assessment, subgroup analysis, sensitivity analysis and publication bias assessment will be performed.

ETHICS AND DISSEMINATION

Either ethics approval or patient consent is not necessary, because this study will be based on literature. The results of this study will be published in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42019130659.

Prosthetic valve thrombosis - association of genetic polymorphisms of VKORC1, CYP2C9 and CYP4F2 genes

Prosthetic Valve Thrombosis (PVT), in spite of the advances in the valve design and the material used, remains a serious complication of mechanical cardiac valve replacement. The factors influencing the development of PVT are: thrombogenicity of the valve, hemodynamics of the transprosthetic blood flow and ineffective anticoagulation. Genetic polymorphism of the genes VKORC1 (-1639 G > A and 1173 C > T), CYP2C9 (*2 & *3 alleles) and CYP4F2 (1347 G > A) are known to influence the anticoagulant dose-effect response. Since there has not been any earlier study on the direct influence of gene polymorphism on the development of PVT, we investigated into this association.Genotyping for the genes VKORC1, CYP2C9 and CYP4F2 was carried out by conventional PCR-RFLP method for 91 consecutive PVT patients. Subjects of our earlier study served as controls (n = 136).Female patients and patients with smaller prosthetic valve size were more prone to developing PVT (68%, n = 62). Patients bearing A allele of CYP4F2 1347 G > A polymorphism exhibited a fivefold increased risk of PVT (OR = 5.022 (1.39-18.04), P = .013). G allele of VKORC1 when analyzed in combination of genotypes showed a fourteen fold increased risk for developing PVT (OR = 14.25 (5.52-36.77), P = 0.001). CYP2C9 (*2&*3) gene polymorphism did not show any significant association with PVT (OR = 1.54 (0.128 - 18.82), P = .731).Patients bearing A allele of CYP4F2 showed an increased risk of developing PVT in our case - control study.

The optimal anticoagulant therapy for mechanical heart valves in a gallbladder cancer patient with hepatic metastases: A case report

RATIONALE

Developing an optimal anticoagulant strategy poses a challenging task in patients with mechanical heart valves (MHVs) throughout their lifetime. We report an optimal anticoagulant therapy in a cancer patient with hepatic metastases after MHV replacement.

PATIENT CONCERNS

A 68-year-old female with MHVs suffered from gallbladder cancer with hepatic metastases. Her international normalized ratio (INR) fluctuated owing to the declined hepatic function.

DIAGNOSES

Gallbladder cancer and hepatic metastases, with a history of mechanic aortic valve replacement and mitral valve replacement.

INTERVENTIONS

Warfarin was discontinued and Vitamin K1 was immediately administrated via intravenous infusion. low-molecular-weight heparin (LMWH) was regarded as a preferable option, and nadroparin at the dosage of 4100IU daily was administered.

OUTCOMES

No adverse event occurred during the patient's hospitalization and two-week follow up after discharge.

LESSONS

LMWH may represent a reasonable alternative regarding the inhibition of thrombus and bleeding in MHVs carriers with cancer and hepatic metastases.

Association of homocysteine and smoking with cerebral microemboli in patients with mechanical heart valves: a transcranial Doppler study

Objectives

Microembolic signals (MES) on transcranial Doppler (TCD) predict stroke and cognitive decline. Plasma levels of total homocysteine (tHcy), a prothrombotic factor, are higher in patients with microemboli in carotid stenosis and in patients with paradoxical embolism. In this study we assessed the association between the level of tHcy and the number of MES in patients with mechanical heart valves (MHVs).

Methods

TCD monitoring was performed to detect MES before and after breathing 100% oxygen and repeated every 2-4 weeks up to six times.

Results

Twenty-five patients with MHVs (mean age: 63.60±10.15 years) participated in this study; 15 were men (66.47±7.25 years) and 10 were women (59.30±12.60 years). In total, there were 126 study visits. In multiple regression, higher tHcy was associated with more MES in both preoxygenation (OR 1.34 (95% CI 1.07 to 1.68, P=0.009)) and postoxygenation (OR 1.40 (95% CI 1.07 to 1.83, P=0.01)) phases. Current smoking and the length of time between the operation and monitoring also correlated with a higher number of MES before and after breathing oxygen, particularly in women.

Conclusions

Higher tHcy and smoking were associated with a higher MES count in both preoxygenation and postoxygenation phases. Because smoking can be stopped and hyperhomocysteinaemia is treatable, these are clinically important findings.