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Coronary artery: The Coronary system is responsible for the supply of oxygen-rich blood to the heart muscle itself. The system originates from the Aorta, and the main Coronary arteries are: Left Main )LM), Left Anterior Descending )LAD), Circumflex (CX) and Right Coronary Artery (RCA).

Different arteries supply blood to different areas of the heart.

The coronary system is more strongly exposed to the development of Atherosclerosis compared with other arterial systems and this fact explains the enormous incidence of Ischemic heart disease.
Coronary artery: One of the arteries belonging to the system nourishing the heart muscle itself and responsible for the oxygen supply to the heart.

This arterial system originates from the Aorta.

It is composed of three main arteries: RCA, LDA and CIRCUMFLEX and their branches.

The Coronary system is one of the arterial systems in the body most strongly exposed to the Atherosclerosis process.
Coronary Heart Disease, Ischemic Heart Disease (IHD ,CHD): A disease characterized by decreased blood flow in the coronary arteries resulting from stenosis.

In most cases, these stenoses (narrowing) is caused by Atherosclerosis, a process in which lipid plaques are formed upon the arterial wall, whereby the lumen is narrowed and less blood can flow in them at any given moment.

If the oxygen requirement at a given time exceeds the possible supply by the stenosed Coronary artery, relative oxygen deficit ensues. This deficit is called Ischemia.

Ischemia can cause biochemical, electrical and temporary functional alterations in the heart and the patient usually experiences distressing pressure pain in the front of the chest, which is known as Angina Pectoris.

The course of Ischemic disease depends on the extent of the lipid plaques, their localization and the processes occurring in them.

If a lipid plaque grows slowly and is stable, gradual appearance of symptoms is the rule, known as stable Angina Pectoris. The characteristic trait of this form of the disease is the appearance of Ischemia when the demand for oxygen exceeds the supply.

Because the highest oxygen requirement occurs during strenuous heart action, physical exercise or mental stress are known triggers for the appearance of ischemic pain.

If processes inside the lipid plaque cause the rupture of its envelope with creation of a blood clot (thrombus) on its surface, the course of ischemic disease can become stormy and result in myocardial infarction, rhythm disturbances and even sudden death.
Coronary risk factors: A medical condition, lifestyle or environmental threat that increases the statistical risk for the development of atherosclerosis in the cardiac vasculature, i.e. the Coronary arteries.

Among these risk factors the following are usually included: advanced age, male gender (during the procreative years, women are usually better protected then men), genetic factors (family history), Hypertension, Diabetes, high blood lipid levels, obesity, lack of physical activity, smoking and mental stress.
Cyanosis: Bluish or livid color of the skin and the mucous membranes due to low oxygen content of the blood.

This is particularly conspicuous in the lips and nails. Cyanosis can appear in various medical conditions, for which the underlying course is low oxygen saturation of the blood, as for example lung diseases, heart defects, in high geographic regions and more.

Cyanosis in inner parts of the lips (that are not exposed to cold), cheeks, tongue and conjunctiva of the eyes, can evidence reduced oxygen saturation of blood secondary to pulmonary or cardiac disease.

Cyanosis appearing in external parts only, such as finger tips, the tip of the nose or the outer parts of the lips can be due to decreased blood flow into the skin because of its exposure to low temperature.
Defibrillation: An electrical shock applied to the heart as treatment aimed at an immediate stopping of rapid rhythm disorders, which constitute a life threatening condition (for example Ventricular Fibrillation).
Defibrillator: A medical device destined for exerting an electrical shock to the heart for immediate stopping of rhythm disorders. Electricity is conducted by means of metallic plates located at predefined points on the chest. Some defibrillators are equipped with an automatic mechanism capable of recognizing a rhythm disorder and initiating the electrical shock accordingly. Some other subcutaneously implantable defibrillators deliver the electrical shock directly to the heart when dangerous rapid rhythm disorders are detected.
Diabetes mellitus: Diabetes is a metabolic disease characterized by high glucose (sugar) concentration in serum and in urine.

The Latin name Diabetes mellitus means "sweet urine".

The main problem underlying Diabetes is relative or absolute deficiency of the hormone Insulin.

This hormone is produced in the pancreas and is secreted into blood as a reaction to increasing sugar levels.

Insulin is responsible for glucose transfer from the blood into various body cells, where glucose is indispensable for the generation of energy.

Diabetics suffer from Insulin deficiency, from impairment in its function or from increased tissue resistance to Insulin and thus, when blood sugar levels increase, an adequate response of Insulin release is absent.

As a result, glucose accumulates in blood. This condition is called Hyperglycemia.

When glucose level surpasses a certain threshold, it is also excreted in urine. This condition is called Glycosuria.

The symptoms resulting from elevated glucose levels are increased secretion of urine, thirst and weight loss.

There are two main types of Diabetes: Type 1 (IDDM, Insulin dependent Diabetes Mellitus) and type 2 (NIDDM, non-Insulin dependent Diabetes Mellitus).

Type 1 Diabetes, also known as youth onset Diabetes, is usually manifested in childhood, its cause is Insulin deficiency resulting from destruction of the pancreatic cells responsible for Insulin secretion. Therapy consists of obligatory external Insulin supply.

Type 2 Diabetes, also called adult onset Diabetes, develops in adults, usually after age 40, is more frequent in females and its incidence increases markedly in obesity. It has a strong hereditary component. Its primary cause is low reactivity or increased resistance of the tissues to Insulin.

This condition of high Insulin resistance is closely related to the condition named "Metabolic Syndrome" or "Syndrome X".

This syndrome includes central obesity (in the abdominal area and around organs), Hypertension, disturbed blood lipid levels, cardiovascular diseases, tendency to hyper-coagulation and more.

Treatment includes changes in life style: physical activity, appropriate diet, weight reduction and orally administered drugs. Sometimes, also Insulin treatment is necessary.

High blood sugar levels increase the risk for the development of vascular damage such as Atherosclerosis, and therefore Diabetes is a major risk factor of Ischemic heart disease.

Vascular damage in diabetes patients is not limited to only cardiac vessels, but can also include multi-system damage involving kidneys, lower extremities, brain, heart and eyes.

An additional damage that afflicts diabetic patients is neural damage.

The combination of peripheral nerve damage resulting in altered sensitivity to pain with increased tendency to Atherosclerosis may make the treatment of diabetic patients more difficult and deteriorate their condition.

For example, due to Coronary artery damage, the diabetic patient is exposed to a higher risk of heart attack on the one hand, while the nerve lesion with altered sensitivity may affect the manifestation of the attack and interfere with early diagnosis, on the other hand.
Diastole: The relaxation phase of the heart muscle.

This phase takes place between two contractions and during it the heart is being filled with blood.
Dyspnea (shortness of breath, breathlessness): Breathing difficulty. Can be the result of many different conditions, including: heart diseases (heart failure), lung diseases (Chronic Bronchitis, Asthma, Emphysema and more) upper respiratory tract disorders (occlusion by a foreign body), metabolic problems and sometimes also mental disorders.
ECG, Electrocardiogram: Recording of the electrical activity of the heart. The heart is a pump activated by electrical power. These electrical potentials can be recorded by ECG. The standard ECG is recorded from 12 different points. These reference points are created by placing electrodes on the body surface surrounding the heart. The points are exactly defined and each electrode records the electrical progress from its point of view. The electrodes are commonly called leads. The standard ECG is a 12-lead ECG. ECG recording can detect various heart problems such as rhythm disturbances or signs of a heart attack. .
Echocardiography: A technique, which uses sound waves (ultrasound) for the imaging of the cardiac anatomy and information regarding wall thickness, size of the cardiac chambers and the function of valves. Sometimes echocardiography is combined with stress test. Echo stress test provides information about the state of the coronary arteries as well.
Edema: Accumulation of fluids in any tissue due to leakage of fluid from a blood vessel into the extracellular space.
Electrical conduction system: A system originating from the natural pacemaker (Sinus) and ending in cells in the ventricles.

This system is capable of rapid transfer of electrical stimuli.

Its composition and structure assure that electric stimuli are transferred in a fully synchronized manner, i.e. each electrical pulse emerging from the Sinus reaches the cells in the ventricles at exactly the same time, which enables effective and powerful contraction.

With age, the conduction systems may be subject to different degenerative processes that in some cases necessitate the implantation of an artificial pacemaker.
Embolus: A particle that wanders with the blood stream from the site where it is created to another remote site, where it can cause arterial occlusion. Embolus can consist of thrombus (blood clot), air, fat and more.
Endocarditis: An inflammation process involving the Endocardium. Such inflammation is usually caused by Rheumatoid arthritis or by bacterial infection. The presenting symptoms are fever and variable heart murmurs. Complications, such as congestive heart failure of embolism are possible
Endocardium: Endocardium A delicate membrane covering the inner heart wall and the valves. Folds of this membrane form the cardiac valves.
Epicardium: The external layer wrapping the heart.
Ergometric stress testing: This test is designated for the identification or exclusion of Ischemic heart disease. In the course of the examination, the patient is submitted to physical exercise (ergometer bicycle or walking on a treadmill) in order to increase the pulse rate. As the pulse rate rises, ECG is recorded aiming at detecting ECG changes that may occur as evidence of cardiac distress caused by relative oxygen deficit.
External cardiac massage: A rescue action, which is part of the resuscitation procedure. The massage is performed by serial exertion of pressure and relaxation on the chest bone, at the rate of about 100 per minute. The massage is kind of external squeezing of the heart causing its voiding and filling to a certain extent and thus preserving cardiac output and blood flow to vital body organs for the duration of the resuscitation.

The quality of cardiac massage and the proficiency of the person performing it are considered as having major importance on the success of the resuscitation procedure.
Extra systole, premature beat: Normally, any electrical pulse engaging the heart muscle during each heart beat begins in the tissue called Sinus (SA node). This tissue has autonomic potential of generating such pulses.

This tissue is also known as natural pacemaker.

In some instances, for various reasons, electrical stimulation can be elicited from other sites in the heart, outside the Sinus, by cells that are under normal conditions not electrically active.

Usually, such impulse will be generated before the normal next impulse from the natural pacemaker, the Sinus, and it is therefore called "premature beat".

Another name for such premature beats is Extra-Systole.

Premature beats can be generated from a supra-ventricular source (from sites located above the ventricles) or from sites located in the ventricles.

In many instances, the reason for the generation of such premature beats is unknown. They are more frequent under the influence of substances such as caffeine, nicotine or alcohol. They can be also associated with cardiac diseases.

Sometimes such premature beats can give a sensation of irregular pulse or of interruptions in the normal heart action.

Most extra systoles do not require medical treatment. The decision about initiating medical treatment for the suppression of premature beats will depend on the subjective feeling of the patient as well as on the cause for their appearance.
Extrasystole, premature beat: See under Premature beat.
Familial hypercholesterolemia: A genetic defect causing elevation of blood cholesterol and lipid levels.
Flutter: A kind of rapid rhythm disorder causing the contraction of the afflicted part of the heart to be ineffective.

When such rapid rhythm affects the atria, it is called atrial flutter. Its consequences are similar to those of Atrial Fibrillation.

However, if this is found in the ventricles, ventricular flutter is an emergency situation requiring immediate life saving intervention. Without treatment this condition deteriorates to Ventricular Fibrillation and cardiac arrest.
Heart (cardia): A muscular organ comprising 4 chambers, located in the center of the chest, between the two lungs, with the apex pointing downwards and to the left.

It is divided by an impermeable septum into two parts, the left and the right heart, .

It is also divided into two compartments (upper and lower) called atria (vestibules) and ventricles.

A one-way valve separates each ventricle from its corresponding atrium.

The heart functions as a pump, which propels blood into the vessels of the body. The right heart pumps oxygen-depleted blood returning from the body organs into the lungs, while the left heart's function is propelling oxygen-enriched blood coming from the lungs into all body organs.

This process is accomplished in the following manner: Oxygen-depleted blood is drained from the organs by the venous system and reaches the right atrium. From there it flows to the right ventricle and when the ventricle contracts it is propelled into the Pulmonary artery.

In the lungs, gas exchange takes place and blood is oxygenated.

The oxygen- enriched blood is transported by the Pulmonary veins to the left ventricle and by the contraction of the latter it is pumped directly into the Aorta, which by means of its many branches supplies oxygen rich blood to all organs of the body.

The synchronized activity of the different heart chambers is possible thanks to the electrical conductive system, which signals and stimulates the contraction and relaxation of the heart muscle.

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