The coronary arteries are responsible for supplying the blood to the heart. They are born in the origin of the aorta artery and are two:
- Left coronary artery (LMCA). After its origin bifurcates into two branches: the anterior descending artery and the circumflex artery.
- Right coronary artery.
The involvement of the coronary arteries causes what is called coronary heart disease or ischemic heart disease. This is due to coronary atherosclerosis, which can be defined as an inflammatory disease of the arteries in which the formation of atheroma plaques (mainly composed of calcium and cholesterol) occurs inside the arteries. Atherosclerosis affects the innermost layer of the arteries (endothelium), which loses elasticity and its ability to dilate or contract when required by the body. The atherosclerotic plaque causes a progressive occlusion of the lumen (from the inside) of the coronary arteries, reducing the flow of blood passing through it and, therefore, there is an imbalance between the supply and demand of nutrients and oxygen Accurate heart muscle.
Atherosclerosis is a chronic process that can take several years to develop. Risk factors that influence the onset and progression of atherosclerosis and, in general, any cardiovascular disease are:
- Gender: Women are generally protected against coronary disease until menopause when they are at increased risk for the disease.
- The family history of ischemic heart disease.
- Arterial hypertension.
- Mellitus diabetes.
Coronary heart disease is usually asymptomatic for years until the disease progresses enough to narrow the vessels significantly: it is at this time when angina pectoris appears. Sometimes a rupture of the atherosclerotic plaque occurs, which causes the formation of a blood clot that completely obstructs the interior of the artery, triggering an acute myocardial infarction.
The most important and characteristic symptom of angina is a pain in the center of the chest, with a feeling of oppression, which appears with exertion and is calmed with rest (it can also be triggered by emotions or cold), and Which may extend to other areas, such as the left arm or jaw. It is called stable angina when pain appears to achieve a given level of effort, and yields in a short time with rest. Unstable angina is one that appears at rest, or when pain increases in frequency, intensity or duration; Unstable angina is a condition more serious than the stable, so it is usually necessary to get the patient to a comprehensive study.
The acute myocardial infarction is necrosis (meaning death) of one of the heart muscle due to complete obstruction of a coronary artery. It is the most serious consequence of progressive coronary disease. The infarct manifests itself with the typical symptoms of angina but with a usually higher intensity and, frequently, with other associated symptoms such as sweating, nausea or vomiting; Sometimes with a sense of imminent death. To prevent the infarction from taking its course we should try to open the coronary artery that has occluded as soon as possible. In an infarct, the greatest life-threatening event occurs in the first few hours, since malignant ventricular arrhythmias may occur and, consequently, a sudden death caused by them. Therefore, the size of the infarct should be limited as much as possible, which is achieved by opening the occluded coronary artery in the shortest possible time.
The best treatment for coronary heart disease is, without a doubt, prevention. Early cardiovascular risk factors should be taken to decrease and delay the appearance of atherosclerotic plaques.
Today we have several therapeutic options for patients who have developed coronary disease. We briefly describe them below.
By administering antianginal drugs (for angina) and antiplatelet drugs, they stabilize the atherosclerotic plaque and decrease the oxygen demand of the heart muscle.
Percutaneous Transluminal Coronary Angioplasty (PTCA)
The coronary artery is opened by a catheter inserted into the femoral artery (in the groin) or the radial artery (at the wrist), thanks to the dilation of a balloon located at the tip of the catheter. Besides dilation usually implant a device known as a stent , a metal mesh that holds open the artery. There are conventional stents (metal mesh only), drug-coated (they are coated with a drug to try not to obstruct the inside of the stent) and resorbable (the mesh is no longer metallic, but a polymer that is reabsorbed and disappears).
An attempt is made to open the occluded vessel by administering an intravenous drug. This drug is intended to dissolve the blood clot that occludes the coronary artery, restoring the passage of blood again. It is used only in patients who are suffering at this time a myocardial infarction when it is not possible to perform a PTCA in a very short time.
Coronary artery bypass surgery attempts to bring back the blood, which carries oxygen and nutrients, to those areas of the heart that are poorly irrigated by the presence of narrowing in the coronary arteries.
The so-called coronary grafts or bridges are used for this purpose. They are arteries or veins of the own patient, which are extracted in the same surgical act and prepared to join them to the coronary arteries. This is what is called bypass or coronary bypass; Is basically a bypass of the bloodstream to save the obstruction in the artery and thus provide the adequate amount of blood to the diseased artery or arteries.
Coronary artery bypass grafting is indicated in the following situations:
- Major disease of the trunk of the left coronary artery.
- A major disease of the 3 coronary arteries.
- An important disease of 2 coronary arteries, one of them being the proximal anterior descending.
- An important disease of the proximal anterior descending when coronary angioplasty is not possible.
- When valvular surgery is necessary and at the same time there are relevant coronary obstructions.
In addition, patients with diabetes or heart contraction failure (ventricular dysfunction) are ideal candidates for revascularization surgery.
Currently, isolated coronary surgery can be performed in two ways, with or without extracorporeal circulation (CPB):
- CEC also called surgery “bomb”: the surgery is performed with the heart stopped, without beating, so must a system of pumps used in surgery to keep blood circulating through the body without the Action of the heart. The grafts that are to be used to make the coronary bridges are removed, and the joints of the grafts are made with the coronary arteries. Once done, the heart is again on the move and disconnected from the ECC.
- Without CEC or surgery “off – pump”: it is to perform the anastomosis of the grafts heart beating through devices that stabilize it so it does not move and can perform sutures, without stopping the heart or subjecting the patient Extracorporeal circulation.
Both techniques have shown good results from surgery, even when many years have passed. In recent years there has been an increase in the number of interventions performed “without pump” since it usually leads to a shorter hospital stay and other advantages in patients at high surgical risk.
The approach to surgery is usual (see the section: During Cardiac Surgery ). An average sternotomy is performed, which is the longitudinal opening of the sternum, the bone that is in the center of the chest. Subsequently, the pericardium (a kind of sac that surrounds the heart) is opened and, in this way, the heart is accessed. At this time of surgery, the grafts are extracted that are going to be used for the coronary bridges. In most cases they will be used:
- Left internal mammary artery: is located behind the breastbone. There are two internal mammary arteries, usually the one that is located on the left side. It dissects without separating it from its origin in the left subclavian artery. In 95% of the cases, it joins the anterior descending artery.
- Saphenous vein: starts at the ankle and runs along the inner side of the leg and thigh. It is completely removed and is used as a bridge to carry blood from the aortic artery to one or several coronary arteries.
In some cases, the right mammary artery or radial artery (located in the forearm) may also be used in selected patients. The purpose of the grafts is to direct the blood flowing into the coronary artery to which they are attached.
After preparing the grafts, the heart is connected to the extracorporeal circulation or, in the case of surgery without a pump, the device that stabilizes the heart is placed and allows us to perform sutures in the coronary arteries. As mentioned, the most common grafts are the left internal mammary artery and the internal saphenous vein. First, the joints are made to the coronary arteries and then joined by the other end (in the case of free grafts such as the saphenous vein or the radial artery) to the aortic artery.
The next step is to proceed to the disconnection of the CEC if this technique is used (see the section: During Cardiac Surgery ), so the heart then returns to its normal heartbeat and its function as a pump that pushes blood flow. Subsequently, the correct functioning of the grafts is verified with a Doppler probe that confirms that enough blood flows through the coronary grafts or bridges.
The closure of the surgical wound is performed according to the usual technique (see the section: During Cardiac Surgery ).
It is important to emphasize that any treatment of coronary disease aims to control the symptoms and stabilize the disease. For this reason, the control of risk factors is essential for patients undergoing coronary surgery. Coronary heart disease can also affect grafts, especially saphenous vein grafts if the risk factors for coronary heart disease are not adequately controlled. The various studies on the durability of grafts have shown that in the case of the mammary artery is 90% at 10 years and 60% in the case of the saphenous vein.