What is the dose of heparin (unfractionated heparin) for a thrombus in the right ventricle?

From the Guidelines

For a thrombus in the right ventricle, the recommended initial treatment is intravenous unfractionated heparin with a loading dose of 80 units/kg followed by a continuous infusion starting at 18 units/kg/hour. This recommendation is based on the most recent and highest quality study available, which suggests that unfractionated heparin is typically given intravenously by using a weight-based dosing algorithm 1. The goal of this treatment is to achieve and maintain an activated partial thromboplastin time (aPTT) of 1.5-2.5 times the normal control value, typically 60-80 seconds.

The heparin infusion should be adjusted based on aPTT values checked every 6 hours until stable, then daily. This treatment should be continued for at least 5-7 days while transitioning to oral anticoagulation with warfarin (target INR 2-3) or a direct oral anticoagulant. Right ventricular thrombi require prompt treatment due to the high risk of pulmonary embolism. Heparin works by binding to antithrombin III, enhancing its ability to inactivate thrombin and factor Xa, thereby preventing clot extension and allowing natural fibrinolytic mechanisms to dissolve the existing thrombus.

Some key points to consider when treating a thrombus in the right ventricle with heparin include:

• The initial dose of heparin is crucial in preventing further clot formation and reducing the risk of pulmonary embolism 1
• Regular monitoring of aPTT values is necessary to adjust the heparin infusion and maintain therapeutic levels
• Patients should be closely monitored for bleeding complications, and platelet counts should be checked regularly to detect heparin-induced thrombocytopenia
• In cases of massive thrombus with hemodynamic compromise, thrombolytic therapy or surgical thrombectomy may be considered.

From the FDA Drug Label

When initiating treatment with Heparin Sodium Injection by continuous intravenous infusion, determine the coagulation status (aPTT, INR, platelet count) at baseline and continue to follow aPTT approximately every 4 hours and then at appropriate intervals thereafter The dosing recommendations in Table 1 are based on clinical experience be adjusted for the individual patient according to the results of suitable laboratory tests, the following dosage schedules may be used as guidelines: Table 1: Recommended Adult Full-Dose Heparin Regimens for Therapeutic Anticoagulant Effect

• Initial Dose 10,000 units, either undiluted or in 50 to 100 mL of 0. 9% Sodium Chloride Injection, USP
• Every 4 to 6 hours 5,000 to 10,000 units, either undiluted or in 50 to 100 mL of 0.9% Sodium Chloride Injection, USP
• Continuous 20,000 to 40,000 units/24 hours in 1,000 mL of 0.9% Sodium Chloride Injection, USP

The dose of heparin for a thrombus in the right ventricle is not explicitly stated in the label. However, for therapeutic anticoagulant effect, the recommended adult full-dose heparin regimens are:

• Intermittent Intravenous Injection: Initial dose of 10,000 units, followed by 5,000 to 10,000 units every 4 to 6 hours.
• Continuous Intravenous Infusion: Initial dose of 5,000 units, followed by 20,000 to 40,000 units/24 hours. It is essential to monitor coagulation status and adjust the dose according to the results of suitable laboratory tests, such as aPTT, INR, and platelet count 2.

From the Research

Thrombus Right Ventricle Dose of Heparin

• The dose of heparin for a thrombus in the right ventricle is not explicitly stated in the provided studies.
• However, the studies discuss the use of unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) in the treatment of venous thrombosis and thromboembolism 3, 4.
• The activated partial thromboplastin time (APTT) is commonly used to monitor UFH therapy, but its therapeutic range can vary depending on the reagent and instrument employed 5, 6, 7.
• The American College of Chest Physicians recommends establishing a heparin concentration-derived therapeutic range for UFH, but this is rarely performed 4, 7.
• Anti-factor Xa monitoring may be superior to APTT measurement in patients with apparent heparin resistance 4.
• LMWHs have more predictable pharmacokinetic and pharmacodynamic properties than UFH and are often preferred for treatment of venous thrombosis and thromboembolism 3, 4.

Monitoring of Unfractionated Heparin Therapy

• The APTT and chromogenic antifactor Xa or antithrombin assays are used to monitor UFH therapy 5.
• Point-of-care (POC) devices are available for monitoring anticoagulation with UFH, but there is some variability in results between devices and reagents 7.
• Establishing a heparin concentration-derived therapeutic range for UFH is important, but it is rarely performed 4, 7.

Low-Molecular-Weight Heparin

• LMWHs are often preferred for treatment of venous thrombosis and thromboembolism due to their more predictable pharmacokinetic and pharmacodynamic properties 3, 4.
• LMWHs can be administered subcutaneously once daily without laboratory monitoring, making them a convenient option for outpatient treatment 3.
• However, anti-factor Xa monitoring may be necessary in patients with severe obesity or renal insufficiency 4.