Anticoagulation is a Double Edged Blade

Anticoagulation is a Double Edged Blade  

Prof. Dr. Mohamed Ahmed Nasr MD, PHD, FACS

Maître as Sciences Medicals (France)  

Membre du College Francals de Chirurgle Thoraclque et Cardiovasculaire

Professor of Cardiac Surgery. National Heart Institute Egypt

Anticoagulation is a type of medication that avoids development of blood clots . It is used for treatment, follow up and control of many human diseases.

Patients that had stokes by thrombosis of one of the cerebral arteries are usually put under anticoagulation therapy. Patients that had myocardial infarction due to coronary heart diseases are usually put under both anticoagulation and anti-platelets aggregation therapies.

Patients with artificial mechanical valve prostheses are put under anticoagulation therapy for life.

Patients with peripheral arterial diseases with diffusely atherosclerotic slender arteries are in need of anticoagulation therapy

Anticoagulation drugs are of two types either Heparin or some of its derivatives of low molecular weight fractionated heparin or anti vitamin K tablets.

Heparin and its derivatives are administered by injection. Heparin is given intravenously in perfusion while anti vitamin K are given in tablet forms. Low molecular weight fractionated heparin are given by sub-cutaneous injection under the skin.

Heparin acts immediately after its administration. It avoids development of blood clots. It assures fluidity of blood stream. Nevertheless it may be a cause of severe bleeding that may sometimes be fatal especially during surgery. Heparin has the advantage of being rapidly antagonized by Protamine infusion. Protamine stops anticoagulation action of heparin . Its is given in perfusion slowly in physiological saline solution. Dose of protamine is calculated as 1,3 the dose of heparin

In open heart surgeries heparin is given to the patient before connection of blood circulation of the patient to the tubes of the heart lung machine. Heparin avoids development of clots in blood of patient during perfusion of the extracorporeal circulation. By the end of surgery protamine is given in perfusion t stop action of heparin and save patient from post operative bleeding

Heparin and its derivatives are very effective drugs but are difficultly administered to patients . they need daily injections to the patients which may be really stressing to the person.

Oral anticoagulation composed of anti vitamin K tablets are easily taken by the patients. Nevertheless they take 48 hours to act . In case of bleeding they are antagonized by injection of vitamine K. The latter medication takes at least 24 hours to act

Patients under anticoagulation therapy are regularly followed up by blood coagulation tests the most reliable tests are the INR and Prothrombin concentration tests

Patients having artificial mechanical valve prosthesis are kept under INR level 2,5-3 and prothrombin concentration between 30% and 35%. In Europ patients are kept under higher levels. Levels chosen in Egypt are really safe.

Not uncommonly patients may die

In pregnancy anticoagulation therapy is a major problem.

from bleeding de to anticoagulation therapy > The most common cause of death in such cases is brain hemorrhage.

In pregnancy anticoagulation therapy is a major problem. Antivitamine K are teratogenic i.e. they induce congenital anomalies in the foetus especially when taken during the first three months of pregnancy. It is during this period that the new born is formed . Taking anti vitamine K during this period help development of congenital malformations . The percentage of occurrence of such anomalies is around 1 to 2%

For years Cardiologists were use to keep pregnant women with mechanical heart valve prosthesis under heparine therapy during the first three months od pregnancy then under anti vitamine K between the 4th and 7th month. Then they are put back on heparine from the 8thmonth until weaning the child off breast feeding. As anti vitamine K drugs do pass the blood milk barrier

Causing bleeding in the new born. This is why cardiac surgeons try to avoid insertion of mechanical heart valve prostheses in women during child bearing period . They use biological valves taken from pork heart valves or bovine pericardium. With the latter prostheses anticoagulation are only needed during the first three months after surgery which allows women to have safe pregnancy without anticoagulation therapy.

Anticoagulation are used in presence of mechanical artificial heart valve prostheses to avoid their obstruction by clot formation which may sometimes be fatal or in need of a new emergency surgery to re replace the prosthesis

Because of the problem seen during shifting of anticoagulation protocol from heparin to oral anticoagulation surgeons decided to keep the pregnant woman under oral antivitamin K pills all through pregnancy provided dose of anticoagulation does not exceed 6 mgrs. per day . With such a dose incidence of development of foetal malformations are around 1%

Health of mother prime

To understand danger of anticoagulation one may say that rat poisons in early 50s was anti vitamine K it was used to ill rats from severe internal hemorrhage

Anticoagulation are very beneficial drugs provided they are used under strict medical follow up with close observation by regular anticoagulation tests The INR and prothrombine concentration

Anticoagulation effect is intensified by taking other medications with the anticoagulants such as none steroid anti inflammatory medications. They were responsible of many major bleeding in patients under anticoagulationtherapy. Many foods decrease effect of anticoagulation . Green vegetables leafs even in soup or salads decrease effect of anticoagulation

Many patients confuse anticoagulation and anti platelets aggregation medications

To develop blood clot blood factors develop the clot anticoagulant play on the clotting process

To act platelets of blood should aggregate creating mesh by their false limbs called pseudo-pods

It I in such mesh that clots develop

Patients with strokes or diffuse coronary heart diseases or after coronary artery bypass grafting are put under medications that avoid platelets aggregation Aspirin and clopidogrel are medications used for avoiding aggregation of blood platelets They are much easily manipulated drugs against clot formation. Many patients confuse anti platelets with anticoagulation

Aspirin in a dose between 80 to 150 mgr. per day acts as antiplatelet while in high dose over 400 mrg. Per day it acts as anti rheumatic pains and may be

thrombogenic i.e. develop clots formation in blood

I wrote this article and tried to simplify it as possible as I can to inform normal citizens of importance of being closely followed up by an experienced physicians to avoid the harmful blade of anticoagulation considered as really a double edged blade