Centre for Chronic Disease Prevention and Control
Cardiovascular Disease
Terms & Definitions
ACUTE MYOCARDIAL INFARCTION: (ICD-9 410) Sometimes called heart attack. A manifestation of ischemic heart disease, describing a severe sudden onset of myocardial necrosis due to the formation of a thrombus in the coronary arterial system obstructing arterial blood flow to that section of cardiac muscle.
AGE-STANDARDIZED RATES: The standardized rate represents what the crude rate would be if the population under study had the age distribution of the standard population. It is the weighted average of age-specific rates applied to a standard distribution of age.
ANEURYSM: A sac formed by the dilation of the wall of an artery, a vein or the heart; it is filled with fluid or clotted blood often forming a pulsating tumor.
ANGINA PECTORIS: (ICD-9 413) A symptomatic manifestation of ischemic heart disease, describing a severe squeezing or pressure-like thoracic pain, brought on by exertion or stress.
ARTERIOSCLEROSIS: A group of diseases characterized by thickening and loss of elasticity of arterial walls. Sometime called "hardening of the arteries".
ATHEROSCLEROSIS: A process in which deposits of yellowish plaques (atheromas) containing cholesterol, lipid material and lipophages are formed within large and medium sized arteries. An atheroma can increase in size and harden over time reducing blood flow and can potientially result in a thrombosis or bleeding into and subsequently clotting off an artery resulting in a mycardio infarction.
BODY MASS INDEX (BMI): A measure of human body size and proportion. It is defined as the weight in kilograms divided by the square of height in meters. (See obesity)
CARDIOVASCULAR DISEASES: (ICD-9 390-459) All diseases of the circulatory system including acute myocardial infarction, ischemic heart disease, valvular heart disease, peripheral vascular disease, arrhythmias, high blood pressure and stroke.
CEREBROVASCULAR DISEASE: (ICD-9 430-438) Diseases of one or more blood vessels of the brain.
CHOLESTEROL: A eukaryotic sterol molecule which is the precursor of bile acids and steroid hormones and an important component of cell membranes affecting their fluidity and permeability. Most is synthesized by the liver and other tissues but some is acquired through the diet. Transportation of cholesterol in the blood plasma is accomplished by specific lipoproteins.
DIABETES: Diabetes mellitus is a chronic syndrome of impaired carbohydrate, protein, and fat metabolism resulting from insufficient secretion of insulin from the pancreas or target tissue resistance to insulin. There are two major classifications, insulin dependent diabetes (IDD) or type I and non-insulin dependent diabetes (NIDD) or type II. Diabetes is a risk factor for cardiovascular disease.
EMBOLISM: The sudden blocking of an artery by a clot or foreign material which has been brought to the sight of lodgement by the blood current.
HYPERTENSION (HIGH BLOOD PRESSURE): High blood pressure is generally defined as diastolic (when the heart is dilating) blood pressure (DBP) equal to or greater than 90 mm HG or systolic (when the heart is contracting) blood pressure (SBP) equal to or greater than 140 mm HG. Hypertension is a risk factor for cardiovascular disease.
ICD: International Classification of Diseases is a disease classification system created by the World Health Organization (WHO), the current version used in Canada is version 9 which was revised in 1977. There is also a "Clinical Modification" version (ICD9-CM) being used in Canada which has extended coding for more precise disease classification. ICD version 10 has been released and will be introduced in Canada in the next few years.
INCIDENCE: The number of instances of illness commencing, or of persons falling ill, during a given period in a specified population.
INFARCTION: An area of coagulation necrosis in a tissue due to local ischemia resulting from obstruction of circulation to the area, most commonly by a thrombus or embolus.
ISCHEMIC HEART DISEASE: (ICD-9 410-414) Any condition in which heart muscle is damaged or works inefficiently because of an absence or relative deficiency of its blood supply; most often causes by atherosclerosis, it includes angina pectoris, acute myocardial infarction, chronic ischemic heart disease and sudden death. Also called coronary heart disease (CHD).
LIFE EXPECTANCY: Life expectancy is a summary measure of the health status of a population. It is defined as the average number of years an individual of a given age is expected to live if current mortality rates continue. In Canada, the life expectancy during the period 1990- 1992 was 75 years for men and 81 years for women. (Life Tables, Canada and the Provinces. Catalog Number 84-537)
LIPOPROTEINS: A combination lipid-protein molecule used to transport lipids (or fats molecules) in the blood. They consist of a spherical core of triglycerides or cholesteryl esters surrounded by a layer of phospholipids, cholesterol and apolipoproteins. There are four principal classes of lipoproteins; high-density lipoproteins (HDL), low-density lipoproteins (LDL), very- low-density lipoproteins (VLDL) and chylomicrons. High levels of LDL in blood plasma and low levels of HDL have been found to contribute to atherosclerosis.
NECROSIS: Cellular death affecting groups of cells, part of a structure or an organ.
OBESITY: A relative term for excessive accumulation of fat in the body, a generally accepted measure of obesity is having a body mass index (BMI) greater than or equal to 25-27. Obesity/physical inactivity are risk factors for cardiovascular disease. (See Body Mass Index, Waste-hip Ratio)
OCCLUSION: The act of closure or state of being closed; an obstruction or a closing off. Coronary occlusion is the complete obstruction af an artery of the heart, usually from progressive atherosclerosis.
PHYSICAL INACTIVITY: A relative term which refers to the lack of exercise, the definition of which varies between researchers. For example, in the Canada Fitness Survey, 1981, individuals were considered physically inactive or 'sedentary' if they reported a usual daily leisure-time energy expenditure of less than 1.5 kcal/kg/day. Obesity/physical inactivity are risk factors for cardiovascular disease.
POTENTIAL YEARS OF LIFE LOST (PYLL): A measure of the relative impact of various diseases and lethal forces on society resulting in youthful or premature deaths. The calculation of PYLL due to a particular cause is the sum of the years that each individual would have lived had they experienced normal life expectation for all persons dying from that cause. (See Life Expectancy).
PREVALENCE: The number of instances of a given disease or other condition in a given population at a designated time; the term usually refers to the situation at a specified point in time.
RELATIVE RISK: The relative risk is a measure of the strength of an association. It is calculated as a ratio of the risk of occurrence of a disease among exposed to that among the unexposed. For example, the relative risk of stroke in women who smoke compared with those who have never smoked is 2.8.
RISK FACTOR: A risk factor is a attribute which is positively associated with the development of a disease but is not sufficient to cause the disease. The generally accepted risk factors for cardiovascular disease are smoking, high blood pressure, high cholesterol, diabetes, obesity/sedintary lifestyle, alcohol, stress, age and socio-economic status. A recently identified potential risk factor for cardiovascular disease is low levels serum folate.
SEDENTARY LIFESTYLE: Loosly defined as low levels of physical acivity over extended periods of time. (see Physical Inactivity). Lack of physical exercise is a risk factor for cardiovascular disease.
SMOKING: A relative term the definition of which varies between researchers. One definition of a "current" smoker is someone who smokes at least one cigarette per day. Smoking is a strong risk factor for cardiovascular disease.
STANDARD MORTALITY RATIO (SMR): The ratio of the number of events observed in a population to the number that would be expected if the population had the same specific rates as a standard population, multiplied by 100.
STENOSIS: Narrowing or constricting of a duct, canal or blood vessel.
STROKE: A condition which results in a reduction of blood flow to a region of the brain resulting in the "death" of brain tissue. Specifically, infarction from hemorrhage (ICD-9 430- 432), thrombolitic/embolitic (ICD-9 433-434) or rupturing aneurysm. Thrombolitic strokes are due to cerebral thrombosis often superimposed on a plaque of atherosclerosis with symptom onset ranging from minutes to days. Embolic strokes are due to cerebral embolism, they usually have a sudden onset of symptoms reflecting abrupt loss of blood flow to the brain region of the occluded artery.
THROMBUS (THROMBOSIS): An aggregation of blood factors, primarily platelets and fibrin with entrapment of cellualr elements, frequently causing vascular obstruction at the point of its formation
TRANSIENT ISCHEMIC ATTACK: (ICD-9 435) Reversible neurological or retinal deficits secondary to decrease in blood flow. Symptoms last for less than 24 hours, ususally less than half an hour. There is complete recovery of function within 24 hours.
WAIST-HIP RATIO: The ratio of waist circumference (cm) to hip circumference (cm). It is used as a measurement of obesity. (See obesity).
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