The heart pumps blood so that it can reach various parts of the body and supply these parts with oxygen and nutrients. The pressure generated by the heart forces the blood to go from the heart to various organs and return from there to be sent again. There is about 5 liters of blood in average adult and heart pumps about 70 ml in each heart beat. The force generated by heart results in pressure which can be measured.
Hypertension is said to occur when the recorded blood pressure is higher than expected for the particular age. Children have lower BP, it gradually rises to adult levels and continues to increase with age in most cases. BP is measured by sphygmomanometer which was earlier mercury based but are now aneroid or electronic. BP is measured as Systolic ( higher value of the two ) and diastolic (lower reading) and written as systolic/diastolic BP in mm of Hg. e.g. 120/80 mm Hg.
Blood pressure at birth is about 70 to 85 /30 to 45 , at 5 yrs 90-110/50-66 , at 10 yr 100-120/60-80. In adults blood pressure is diagnosed when it is usually more than 140/90 mm Hg.
In most cases, there is no apparent cause. Suspicion usually falls on genetic disease, high salt intake, higher weight etc. in younger patient sometimes a cause is detected. It is often due to kidney disease, hormonal disorders, blood vessel diseases or diseases disturbing immunity. It can at times be caused by drugs like steroids and analgesics.
Most patients have no symptoms due to high blood pressure. It is only the measurement of blood pressure which reveals the diagnosis. Some patients with high blood pressure may have headaches, dizziness, throbbing or at times shortness of breath. If blood pressure rises suddenly to very high levels it may cause emergencies. These may include vision loss, renal failure, alteration in consciousness ( drowsiness or unconsciousness), or heart failure (manifested as breathlessness worse on lying down or activity)
Clinically it is diagnosed by BP measurement, usually on more than one occasion while a person is sitting with back supported. 2 or 3 readings may be taken and the lower readings are usually more accurate. If in doubt multiple readings can be taken while the person is continuing his activities (ABPM or ambulatory BP monitoring). Eyes are checked as blood vessels can be seen in the retina, ECG and X Ray Chest may show heart enlargement.
Lab tests are done to find the cause of high blood pressure if any, its effects on various organ systems and complications. The usual tests done are Blood counts, urine routine examination, Blood Urea, S Creatinine, S electrolytes, Blood Sugar, Lipid profile in blood, ECG, X Ray of chest and Ultrasonography of abdomen. In special cases hormones may be measured or Doppler Ultrasound studies are done to check blood flow and vessels in different areas.
Complications arise if the blood pressure is very high or it has been present for a long time. Not all persons with high BP get complications. Some of the complications are :
Coming up soon :
Treatment of high blood pressure
Swine flu and other influenzas