Patients with Artificial Heart Valves: Guide to INR Adjustment Before and After Surgery

1. Introduction

Artificial heart valves are a replacement for damaged heart valves, improving heart function and quality of life for patients. However, the use of artificial heart valves also comes with some risks and requires careful monitoring and adjustment of INR (International Normalized Ratio), especially before and after surgery.

2. Types of Artificial Heart Valves

There are two main types of artificial heart valves:

• Bioprosthetic valves: These are made from natural materials such as animal or human tissue. They have the advantage of not requiring long-term anticoagulant medication, but their lifespan is usually shorter than mechanical valves.
• Mechanical valves: These are made from artificial materials such as metal or carbon. They have the advantage of a longer lifespan than bioprosthetic valves, but require lifelong anticoagulant medication.

3. Risks Associated with the Use of Artificial Heart Valves

Patients with artificial heart valves may experience the following risks:

• Bleeding: Anticoagulant medications can increase the risk of bleeding, especially during surgery or accidents.
• Valve thrombosis: Blood clots can form in the heart or artificial valve, leading to valve obstruction and heart failure.

4. INR Adjustment Before and After Surgery

4.1. What is INR?

INR is a measure of how long it takes blood to clot. Normal INR ranges from 0.8 to 1.2. Patients using artificial heart valves need to maintain their INR within a certain range to reduce the risk of thrombosis and bleeding.

4.2. INR Adjustment Before Surgery

Elective surgery:

• Stop anticoagulant medication (AVK) such as Warfarin, Acenocumarol,… to achieve INR < 2 (for patients with low thrombosis risk) or INR < 2.5 (for patients with high thrombosis risk).
• Then use intravenous Heparin to maintain INR.
• Stop Heparin 6-12 hours before surgery.
• Proceed with surgery when INR ≈ 2 (most bleeding complications occur when INR > 1.5).
• 6-12 hours after surgery, if there is no surgical bleeding (< 1ml/kg/h), resume Heparin to achieve INR ≈ 2 (for patients with low thrombosis risk) or INR ≈ 2.5 (for patients with high thrombosis risk).
• Resume AVK when it is safe to swallow again (it takes 2-3 days for AVK to reach the therapeutic range).
• While waiting for AVK to become effective, continue with unfractionated Heparin and only stop Heparin when INR reaches the desired value twice consecutively.

Urgent surgery (can wait 12-24 hours):

• Stop AVK.
• Use Vitamin K (1mg oral or intravenous) or Prothrombin Complex Concentrate (PPSB) to achieve INR < 1.5 before surgery.

Extremely urgent surgery:

• Use PPSB (1UI/Kg factor IX) to reduce INR by 0.15 (or increase PT by 1.5%).
• Administer fresh frozen plasma (if PPSB is unavailable or there is a deficiency in clotting factors).

5. Note:

• INR adjustment should be performed by an experienced cardiovascular specialist.
• Patients should adhere to scheduled appointments for follow-up and INR monitoring.
• Patients should report any unusual health changes to their doctor, especially signs of bleeding such as nosebleeds, bleeding gums, easy bruising, black stools, etc.
• Patients should keep a record of their artificial heart valve type, anticoagulant medication being used, and appointment schedule for use when needed.

6. Conclusion

INR adjustment is a crucial part of managing patients with artificial heart valves. Adhering to doctor’s recommendations will help reduce the risk of bleeding and thrombosis, protect health and improve quality of life for patients.

Note: The information in this article is for general knowledge and should not be considered as a substitute for professional medical advice. Patients should consult with their doctor for personalized advice and treatment.