The World Health Organization (WHO) has defined the term hypertension as, “a persistent elevation of the systolic blood pressure above 140 mmHg and diastolic blood pressure above 90 mmHg.” The blood vessel type that is being measured in this case is the arterial pressure. When systemic arterial blood pressure is elevated, this indicates that the heart is working harder than it should to be able to pump the blood throughout the whole body. The normal value of blood pressure is 120/80 mmHg in adults.
Types of Hypertension
Essential Hypertension is also called primary or idiopathic hypertension. Idiopathic means the cause is unknown in nature. This is marked by a loss of elastic tissue and arteriosclerotic changes in the aorta and larger vessels, coupled with decreased caliber of the arterioles. This usually occurs between 35 to 50 years of age. This is more common in men over 35, women over 45, with African-American men affected twice as often as white men and women.
A benign type of hypertension is marked by a moderate rise in blood pressure marked by a gradual onset and prolonged course
This type of hypertension is characterized by a rapid onset and short dramatic course with a diastolic blood pressure of more than 150 mmHg.
Secondary hypertension is characterized by elevation of the blood pressure as a result of another disease such as renal parenchymal disease, Cushing’s disease, pheochromocytoma, primary aldosteronism, coarctation of the aorta.
Risk Factors for Hypertension
- Heredity – Family history for cardiovascular disorders such as hypertension are at risk to develop these diseases.
- Obesity – high fats and high cholesterol diet predisposes a person to atherosclerosis. This results to increased cardiac workload. The heart has to pump blood supply to a larger body surface area. May also be characterized by rise in serum lipid levels.
- Personality type or Behavioral Factors – the type A behavior pattern, characterized by competitiveness, impatience, aggressiveness and time urgency has been correlated to coronary artery diseases and hypertension, although the mechanism is unknown.
- Stress – Sympathetic response stimulation causes increased secretion of norepinephrine. This results to constriction of blood vessels and increase in pulse rate. Increased blood pressure and increased cardiac workload occurs as a result
- Cigarette smoking – Nicotine causes constriction of blood vessels and spasm of the arteries. It also increase myocardial oxygen demands and adhesion of platelets. In addition, cigarette smoking has been associated with decresed levels of HDL.
- Hypercholesterolemia – increased LDL damages the endothelium (inner wall of the arteries) and causes accumulation of fatty deposits and plaques on endothelial lining and proliferation of smooth muscle cells.
- Inceased sodium intake predisposes a person to hypertension because sodium retains water and increases blood volume.
- Pain similar to angina pain; pain in calves of legs after ambulation or exercise (intermittent claudication), dizziness, epistaxis, dyspnea on exertion
- Blood pressure consistently above 140/90 mmHg, retinal hemorrhages and exudates, edema of extremities
- Rise in systolic blood pressure from supine to standing position (indicative of essential hypertension)
The pathophysiology of hypertension is complex and involves modifiable and non-modifiable risk factors. Hypertension could be a symptom of another underlying disease. The precise causative factor for most cases of hypertension cannot be identified. That is why it is very complex. The heart is very much inter-related with the other organs and body systems which makes hypertension a multi-factorial condition. For hypertension to occur, there must be a change in one or more factors affecting peripheral vascular resistance or cardiac output. Genetics, age, diet, exercise, etc. are just a few of the many factors that affect it. This is the same reason why hypertension is also considered a lifestyle disease. In addition, there must also be a problem with the control systems that monitor or regulate the blood pressure. Hypertension may be caused by increased sympathetic nervous system activity related to dysfunction of the autonomic nervous system, increased renal reabsorption of sodium, chloride, and water related to a genetic variation in the pathways by which the kidneys handle sodium. The serum electrolytes greatly affect the overall condition of the vascular system as well as the blood pressure. Increased activity of the rennin-angiotension-aldosterone system, resulting in the expansion of the extracellular fluid volume and increased systemic vascular resistence. The higher the volume of blood pumped in the blood vessels, the higher the pressure. Decreased vasodilation of the arterioles related to dysfunction of the vascular endothelium because the condition of the arterial walls greatly affects the pressure changes. The more constricted a blood vessel becomes, the more pressure is added on the heart to pump the blood. Also, resistance to insulin action, which may be a common factor linking hypertension to diabetes and hypertriglyceridemia, obesity and glucose intolerance. Increased glucose content in the blood makes it more viscous and makes the blood more difficult to pump. Age also makes the blood vessels more prone to atherosclerosis or plaque formation.
Diagnosis of hypertension is done on a basis of persistent high blood pressure readings. This is usually done with three consecutive high blood pressure measurements using a sphygmomanometer, which can be three separate visits to the doctor for assessment. Initial assessment also includes history and physical examination. To further know what causes the increase in blood pressure, serum studies are done such as blood chemistry.
- Diet and weight reduction (restricted sodium, kilocalories and cholesterol intake)
- Lifestyle changes: alcohol moderation, exercise, regimen, cessation of smoking, reduction of stress.
- Blood pressure monitoring to evaluate effectiveness of treatment regimen.
- Antihypertensive drug therapy