The importance of anticoagulation therapy control in patients with artificial heart valves (prostheses) is fundamental, as they require this treatment to prevent the formation of clots and thrombi, and therefore, to allow the prostheses to continue functioning.
The anticoagulant treatment is administered in the form of oral medication, which is absorbed by the digestive tract and incorporated into the blood, where it acts on coagulation by delaying the formation of the blood clot. This delay is what allows the blood not to have time to coagulate even when it is “stagnant” touching the prosthesis which it considers “a foreign body”.
This is what makes it “indispensable” to permanently maintain an adequate level of anticoagulation when carrying a mechanical heart valve prosthesis.
Blood has the property of remaining liquid while it is inside the circulatory system (heart, arteries and veins), but it becomes solid, i.e. it coagulates when it detects that it has left its place. This property has saved our lives throughout evolution. Therefore, when a wound occurs and the blood leaves the circulation, it coagulates in a few minutes, preventing its continued loss. The problem arises when the blood passes through the mechanical heart valves and interprets for a few moments that it is not “in place” and initiates the clotting process. The passage through the valve is very fast, there is hardly any time for clot formation, but mechanical prostheses are not as perfect as our valves, and leave “corners” in which a very small part of the blood “stops”, which can coagulate and “stick” to the prosthesis forming a “blood thrombus”, microscopic at first, but which tends to grow little by little in a continuous way.
This has two very dangerous effects:
- Embolism: when the thrombus reaches a certain size, the force of the blood stream can drag it away, pulling it out of the heart. It thus becomes a small (or not so small) “plug” that circulates through the arteries until it reaches an artery smaller than the clot. Unable to pass through it, it ends its journey, but “closes” the passage of blood through the “clogged” artery. This is what we call an embolism (embolus is the moving part of a syringe, which closes and drives the fluid out).
- Prosthesis thrombosis: This is the second major problem. The clot that has progressively grown next to the prosthesis gradually closes the orifice through which the blood passes, causing an obstruction called stenosis. At a certain point, this growth reaches the moving parts of the prosthesis, which open and close with each heartbeat. When this happens, the valve is rendered useless. Since it does not open properly, it does not allow blood to pass through. When it does not close, part of the blood that has managed to pass through “goes backwards”, causing what we call “insufficiency”.
Control in the combination of anticoagulant treatment, nutrition
The efficacy of self-monitoring or home control of anticoagulant treatment is increasingly proven, since patients learn to know their personal variations, to relate them to their bowel habits, diet, medication intake, etc. In this way, the doses can be modified, adjusting them to the level of anticoagulation recommended for the type of prosthesis.
In addition, this control of the patient allows them greater freedom in their diet, since they can act according to their changes, as well as prevent disorders caused by medications or digestive problems.