The underlying cause of Coronary Heart Disease (CHD) is in the majority of cases atherosclerosis. Atherosclerosis narrows the arteries nourishing the heart muscle, and if the narrowing exceeds a certain level, the heart suffers from a deficient oxygen supply and is in danger of damage – the acute myocardial infarction.
CHD with a certain degree of simplification may be divided into acute and chronic:
Acute forms:
Among the acute forms of CHD are acute myocardial infarction (MI), unstable angina pectoris and sudden death. These conditions constitute an immediate threat to the patient’s life and require immediate hospital treatment. The causes of unstable angina pectoris and MI is the critical degree of narrowing and obstruction of the coronary artery nourishing the heart muscle. Its full or partial occlusion usually occurs when the so called instable atherosclerotic plague breaks, the blood platelets are then trapped in the place of the rupture and the clot gradually closes the lumen of the artery.
Unstable angina pectoris is in fact a preinfarctional condition clinically manifested by newly occurring intense symptoms and progression of the already existing ones. In most cases we refer to chest pains that in the case of unstable angina pectoris start occurring in minimal workload or at rest. Such increase in pain is always alarming and requires immediate medical attention. In a majority of cases, appropriate treatment, i.e. early performed catheterization, prevents the risk of MI.
An acute MI differs from unstable angina pectoris by the fact that it causes irreversible damage to the heart muscle. The part of heart in the vicinity of the obstructed artery dies. Since the heart muscle does not have the ability to regenerate, the loss of muscle cells is permanent and only scar tissue remains in the place where the myocardial infarction occurred . The severity of the infarction determines the amount of the decrease in the efficiency of the heart and whether the symptoms of heart failure will be observed in the patient. The extent of infarction depends on a few important factors. One of them is the location of the occlusion in the cornary artery. The heart muscle is supplied by 3 main coronary arteries which are then separated into smaller branches. The extent of MI is therefore much greater if the occlusion occurs in the beginning of the artery and smaller if one of the smaller branches is closed. Another important factor is the length of time of the coronary artery occlusion, i.e. the period time during which the oxidised blood flow to a particular part of the heart was disrupted.
It is time that plays an important role in present day modern cardiology when cardiologists are capable of restoring blood flow in an obstructed coronary artery with the help of heart catheterization. In order to shorten this period of time, it is necessary to inform the public about the symptoms of acute MI. Just as in all the forms of CHD, the main symptom of acute MI is the typical chest pain (twiching, burning or pressure spreading to the neck, back or left upper extremity) which is present a longer time, usually more than 20 minutes. The chest pain is usually accompanied by shortness of breath, sweating, nausea, weakness, etc. When these symptoms occur, it is absolutely crucial that heart attack victim be immediately moved to hospital by emergency health services assisted by a doctor. The reason is not only the mentioned role of time but also the fact that a the great number of people affected by MI, die in the preadmission period.
The cause of death in the majority of MI cases is life endangering arrhythmia, (chamber fibrillation, chamber tachycardia). This condition can easily be dealt with by a doctor. Death by arrhytmia in acute MI is the typical cause of sudden death. Although severe chest pains when at rest are common symptoms, not all chest pains originate in the heart. Chest pains are symptomatic for a number of illnesses, such as those of the digestive system, pulmonary diseases, pleura ones and most frequently of the musculoskeletal system. The role of the doctor is to identify the cause of the chest pains or at least to eliminate the most severe ones. CHD is unquestionably one of them. In addition to a case history given by the patient, ECG and echocardiographic test and blood sample analysis play an irreplaceable role to help them identify the cause and extent of damage.
An MI is typically accompanied by changes in ECG readings, abnormal movements of the part of heart observed during echocardiography and the presence of substances released into the blood from the dying heart tissue. If the acute MI is diagnosed, the patient is scheduled for a heart catheterization. A catheterization opens the obstructed coronary artery and renews the supply of oxidised blood to the heart muscle, thus limiting the extent of damage to it. All medical professionals try to minimise the period of time between the onset of MI symptoms in a patient and the heart catheterization. Experince has proved that within 12 hours of the onset of symptoms, all the heart tissue supplied by the obstructed coronary artery dies and catheterization cannot favourably affect the infarction extent then.
So what is a heart catheterization? This term denotes the insertion of fine catheters towards the heart. A catheter is usually introduced into the arterial system through either the femoral artery in the groin, or the radial artery in the wrist finally reaching the aorta, the main artery in the body – all done under radiological control. Where the heart and the aorta meet is the point of origin of the coronary arteries that are inspected and in which the radiological contrasting medium is then applied. The doctors are thus able to asses the velocity of bloodflow and find the place where the coronary artery is obstructed or critically narowed. The heart catheterization just described is known as the left-sided heart catheterization. Taking pictures of the coronary arteries is called coronarography.
In acute MI, coronography is usually followed in most cases by a ,so called, coronary angioplasty (PCI, PTCA). An angioplasty consists of the application of a special small baloon inflated in the obstructed area of the artery to enable blood to flow through the artery again. A stent resembling a tiny pen spring is inserted to prevent repeated narrowing. This area of cardiology, labelled as invasive, has developed so quickly that a wide range of stents are now available to doctors. These stents differ in length and width. Some stents are coated with slow release medications that prevent a vessel from repeatedly narrowing. These medications are called drug-eluting stents.
Even if a patient has had a highly successful catheterization, he/she is still at risk of a repeated heart event and must adopt the behaviours of a healthy lifestyle as well as accept a life-long dependence on medication. A healthy life style means not smoking cigarettes, cutting down on animal fats in food, getting regular physical excercise, reducing weight in the case of overweight and obese people, and last but not least regular medical check-ups focused on controlling blood pressure, monitoring blood fats (cholesterol, triglycerides) and adequately treating diabetes in diabetics.
Chronic form:
Each clinically proved ischemic disease, e.g. infarction in the past, which is not currently manifested by chest pains or breathlessness, is considered to be a chronic disease.