“Bridging” and Mechanical Heart Valves

Management of perioperative anticoagulation in patients with mechanical heart valve replacement undergoing laparoscopic cholecystectomy: a case report of postoperative cerebral embolism

Patients with mechanical heart valve replacement require lifelong anticoagulation therapy, and additional surgeries can pose a risk of bleeding and thromboembolic events due to the need for perioperative anticoagulation management. Here, we present a case report of a patient who underwent laparoscopic cholecystectomy (LC) and endoscopic retrograde cholangiopancreatography (ERCP) after mechanical heart valve replacement and experienced postoperative cerebral embolism. The management of perioperative anticoagulation in these patients is discussed, including strategies for minimizing the risks of bleeding and thromboembolic events during and after surgery.

Physicians Adherence to Evidence-Based Guidelines as a Major Predictor to Anticoagulant-related Medication Errors Incidence and Severity

AIM

Anticoagulants represent a main source of medication errors (MEs) and complications that cause catastrophic implications posing an obligation on health care providers to assess anticoagulant related MEs and factors affecting their occurrence. This study investigates the occurrence and severity of prescribing MEs in patients on anticoagulants and explores their potential predictors.

METHODS

a prospective cohort study in a tertiary hospital on 116 patients with a total of 2166 anticoagulant doses.

RESULTS

Forty-four percent of prescribed anticoagulant doses resulted in MEs with low molecular weight heparin (LMWH) and unfractionated heparin (UFH) causing 61% and 34% respectively of the total MEs. More than 50% of all MEs were incorrect doses (high and low) shared between heparin and tinzaparin. The highest severity of error was Category D followed by Category F and C. Poisson regression analysis model revealed that female (IRR 1.32, 95% CI 1.13-1.54, p<0.001), bridging (IRR 1.52; 95% CI 1.10 - 2.09; p=0.011), VTE prophylaxis (IRR 7.65; 95% CI 4.88 - 12.02; p<0.001), physician non-adherence (IRR 2.71; 95% CI 2.22 - 3.29; p<0.001), and polypharmacy (IRR 1.68; 95% CI 1.26 - 2.23; p=0.036) were predictors of the higher incidence of MEs. Ordinal logistic regression analysis demonstrated that physician non-adherence (OR 24.67; 95% CI 5.54 - 207; p<0.001) was the main predictor of increased error severity.

CONCLUSION

The major predictor in increasing both MEs incidence and severity is physician adherence to evidence-based guidelines (EBG). Strict regulations of anticoagulant prescribing through an anticoagulant stewardship program are a necessity.

Anticoagulation and antiplatelet therapy in patients with prosthetic heart valves

BACKGROUND

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.

METHODS AND DISCUSSION

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.

Intravenous heparin dosing strategy in hospitalized patients with atrial dysrhythmias

Patients with non-valvular atrial fibrillation (AF) have an elevated stroke risk that is 2-7 times greater than in those without AF. Intravenous unfractionated heparin (UFH) is commonly used for hospitalized patients with atrial fibrillation and atrial flutter (AFL) to prevent stroke. Dosing strategies exist for intravenous anticoagulation in patients with acute coronary syndromes and venous thromboembolic diseases, but there are no data to guide providers on a dosing strategy for intravenous anticoagulation in patients with AF/AFL. 996 hospitalized patients with AF/AFL on UFH were evaluated. Bolus dosing and initial infusion rates of UFH were recorded along with rates of stroke, thromboemobolic events, and bleeding events as defined by the International Society on Thrombosis and Haemostasis criteria. Among 226 patients included in the analysis, 76 bleeding events occurred. Using linear regression analysis, initial rates of heparin infusion ranging from 9.7 to 11.8 units/kilogram/hour (U/kg/h) resulted in activated partial thromboplastin times that were within therapeutic range. The median initial infusion rate in patients with bleeding was 13.3 U/kg/h, while in those without bleeding it was 11.4 U/kg/h; p = 0.012. An initial infusion rate >11.0 U/kg/h yielded an OR 1.95 (1.06-3.59); p = 0.03 for any bleeding event. Using IV heparin boluses neither increased the probability of attaining a therapeutic aPTT (56.1 vs 56.3 %; p = 0.99) nor did it significantly increase bleeding events in the study (35.7 vs 31.3 %; p = 0.48). The results suggest that higher initial rates of heparin are associated with increased bleeding risk. From this dataset, initial heparin infusion rates of 9.7-11.0 U/kg/h without a bolus can result in therapeutic levels of anticoagulation in hospitalized patients with AF/AFL without increasing the risk of bleeding.

Cost of vitamin K antagonist anticoagulant treatment in patients with metallic prosthetic valve in mitral position

Background:

The initiation of oral anticoagulation therapy after valve replacement surgery requires strict monitoring because these patients are at high risk for the development of thrombotic complications and present an increased risk of bleeding.

Objectives:

The aim of this study was to examine the total healthcare costs of oral anticoagulant treatment with vitamin K antagonists in patients with metallic prosthetic valves in the mitral position.

Methods:

Data from clinical records were used in the study including international normalized ratio results, number of medical visits, type of anticoagulant, use of rescue medication and hospital admissions from related complications. The drug cost was calculated based on the official Spanish Ministry of Health price list. Monitoring expenses were included in the cost of the medical supplies used in the procedures. Hospitalization costs were calculated using the diagnosis-related group price for each case.

Results:

We collected data from 151 patients receiving oral anticoagulation therapy with vitamin K antagonist who were diagnosed with mitral prosthesis (n = 90), mitro-aortic prosthesis (n = 57), and mitral and tricuspid prosthesis (n = 4). The total direct healthcare cost was €15302.59, with a mean total cost per patient per year of €1558.15 (±2774.58) consisting of 44.38 (±42.30) for drug cost, €71.41 (±21.43) for international normalized ratio monitoring, €429.52 (±126.87) for medical visits, €26.31 (±28.38) for rescue medication and €986.53 (±2735.68) for related complications.

Conclusion:

Most direct healthcare costs associated with the sampled patients arose from the specialist-care monitoring required for treatment. Good monitoring is inversely related to direct healthcare costs.

Utility of a dedicated pediatric cardiac anticoagulation program: the Boston Children's Hospital experience

Congenital heart disease is the leading cause of stroke in children. Warfarin therapy can be difficult to manage safely in this population because of its narrow therapeutic index, multiple drug and dietary interactions, small patient size, high-risk cardiac indications, and lack of data to support anticoagulation recommendations. We sought to describe our institution's effort to develop a dedicated cardiac anticoagulation service to address the special needs of this population and to review the literature. In 2009, in response to Joint Commission National Patient Safety Goals for Anticoagulation, Boston Children's Hospital created a dedicated pediatric Cardiac Anticoagulation Monitoring Program (CAMP). The primary purpose was to provide centralized management of outpatient anticoagulation to cardiac patients, to serve as a disease-specific resource to families and providers, and to devise strategies to evolve clinical care with rapidly emerging trends in anticoagulation care. Over 5 years the CAMP Service, staffed by a primary pediatric cardiology attending, a full-time nurse practitioner, and administrative assistant with dedicated support from pharmacy and nutrition, has enrolled over 240 patients ranging in age from 5 months to 55 years. The most common indications include a prosthetic valve (34 %), Fontan prophylaxis (20 %), atrial arrhythmias (11 %), cardiomyopathy (10 %), Kawasaki disease (7 %), and a ventricular assist device (2 %). A patient-centered multi-disciplinary cardiac anticoagulation clinic was created in 2012. Overall program international normalized ratio (INR) time in therapeutic range (TTR) is favorable at 67 % (81 % with a 0.2 margin) and has improved steadily over 5 years. Pediatric-specific guidelines for VKOR1 and CYP2C9 pharmacogenomics testing, procedural bridging with enoxaparin, novel anticoagulant use, and quality metrics have been developed. Program satisfaction is rated highly among families and providers. A dedicated pediatric cardiac anticoagulation program offers a safe and effective strategy to standardize anticoagulation care for pediatric cardiology patients, is associated with high patient and provider satisfaction, and is capable of evolving care strategies with emerging trends in anticoagulation.

Emerging trends in heart valve engineering: Part III. Novel technologies for mitral valve repair and replacement

In this portion of an extensive review of heart valve engineering, we focus on the current and emerging technologies and techniques to repair or replace the mitral valve. We begin with a discussion of the currently available mechanical and bioprosthetic mitral valves followed by the rationale and limitations of current surgical mitral annuloplasty methods; a discussion of the technique of neo-chordae fabrication and implantation; a review the procedures and clinical results for catheter-based mitral leaflet repair; a highlight of the motivation for and limitations of catheter-based annular reduction therapies; and introduce the early generation devices for catheter-based mitral valve replacement.

Nanofibers coated on acellular tissue-engineered bovine pericardium supports differentiation of mesenchymal stem cells into endothelial cells for tissue engineering

Aim: This study aimed to develop biodegradable, polymer-based nanofibers coated on acellular tissue-engineered bovine pericardium (ATEBP) for cell interfaces, enabling more exquisite functionality, such as mesenchymal stem cell (MSC) adhesion, proliferation and differentiation into endothelial cells for tissue engineering. Materials & methods: ATEBP coated with nanofibers of poly(L-lactic acid)-co-poly(ε-caprolactone) (PLACL) and a blend of PLACL and gelatin were analyzed for human bone marrow-derived MSC adhesion, proliferation and differentiation into endothelial cells. Results: The cell culture-based approach showed an increase in human bone marrow-derived MSC adhesion, proliferation and differentiation into endothelial cells on ATEBP coated with PLACL/gelatin nanofibers compared with ATEBP and PLACL nanofibers coated on ATEBP. Conclusion: ATEBP coated with PLACL/gelatin nanofibrous scaffolds, along with human bone marrow-derived MSCs differentiated into endothelial cells, might improve the scaffolds’ functionality for tissue engineering.

Original submitted 5 July 2012; Revised submitted 24 January 2013

Update on perioperative bridging in patients on chronic oral anticoagulation

Oral anticoagulation (OAC) with vitamin K antagonists is commonly used for long-term prevention or treatment of arterial or venous thromboembolism. In the USA alone, approximately 250,000 patients will require temporary interruption of OAC annually. Managing anticoagulation in those patients on chronic OAC who require invasive procedures continues to be a major clinical dilemma. This article summarizes the existing evidence in light of the recommendations of the American College of Chest Physicians. Management of anticoagulation in the perioperative period will continue to be an important clinical challenge and an evolving area of research. If new oral anticoagulants are successful in replacing warfarin, the entire perioperative anticoagulation scene will change.