Increased blood pressure is the one of the most common clinical problems, with one of every four adults suffering from it. Hypertension is the leading underlying cause for cardiovascular disease morbidity and mortality. It is often associated with other risk factors like Diabetes, which greatly increase the risk for heart diseases. A middle aged person has 90% chances of developing hypertension during his lifetime.
Blood pressure is normally measured as two values, the systolic and the diastolic values. For example, your blood pressure is recorded as 126/82 mmHg, this means that your systolic blood pressure is 126 and diastolic blood pressure is 82 mmHg.
Systolic blood pressure represents the pressure in the arteries at the time of heartbeat, that pumps blood out of the heart. The diastolic blood pressure represents pressure in the arteries in between the heartbeats, when heart gets refilled by blood. Diastolic blood pressure, therefore is the lowest blood pressure, arteries are subjected to.
What is hypertension?
Hypertension is persistently increased pressure in our arteries. The normal upper limit for systolic blood pressure is 140 mmHg, and that for diastolic blood pressure is 90 mmHg.
American Heart Association(AHA) recommends blood pressure to be categorized as
mm Hg (upper #)
mm Hg (lower #)
|Normal||less than 120||and||less than 80|
|Prehypertension||120 – 139||or||80 – 89|
|High Blood Pressure|
(Hypertension) Stage 1
|140 – 159||or||90 – 99|
|High Blood Pressure|
(Hypertension) Stage 2
|160 or higher||or||100 or higher|
(Emergency care needed)
|Higher than 180||or||Higher than 110|
A single reading of elevated blood pressure does not mean that one has hypertension. You are hypertensive if your multiple blood pressure readings are high. Home recordings are more useful as they represent blood pressures in a relaxed environment.
What are the types of hypertension?
Hypertension is classified into Essential or primary hypertension, and secondary hypertension.
Essential hypertension accounts for 90-95% of all hypertension patients. For essential hypertension, no underlying cause for elevated blood pressures can be found.
Secondary hypertension is caused by a definite underlying cause with known mechanism of increased blood pressure, like chronic renal disease.
What causes hypertension?
To understand the causes of increased blood pressure, we first need to understand a few basic concepts. Blood pressure is essentially dependent on two things, Cardiac output and peripheral vascular resistance.
Cardiac output, as the name suggests, is the amount of blood pumped(output) by the heart in a minute, and peripheral vascular resistance is the resistance offered by the small blood vessels to flow of blood. Cardiac output is again determined by the strength of contraction of heart muscles and by volume of circulating fluid in blood vessels.
Blood pressure increases if the cardiac output increases, as happens in case of increases blood volumes. Blood volume can increase if our body retains more sodium than it can excrete from kidneys. The retention of sodium can be from certain factors that prevent urinary sodium excretion or from decreased ability of kidneys to secrete sodium. That is why many drugs used to lower blood pressure increase urinary sodium excretion, and reduce elevated blood pressures by reducing the amount of circulating blood volumes.
Blood pressure also increases when the peripheral vascular resistance increases. This happens when the small blood vessels become more stiff as happens with ageing. Blood vessels with more flexible walls can accommodate more blood during heart beats by the stretching of their walls, without significant increase in pressure, and this is called ‘Compliance’. When blood vessels become more stiff, small increase in blood volumes can drastically increase the pressure.
How to measure blood pressures?
Blood pressures are recorded using sphygmomanometer, which consists of an inflatable cuff, a mercury dial and a pump to inflate the cuff.
While monitoring the blood pressure, the person should be seated comfortably without crossing legs. The healthcare provider wraps the inflatable cuff around the arm at level of heart, and inflates it using the hand held pump. While deflating certain sound called ‘Korotkoff’s sounds’ are heard using a stethoscope kept over the artery in the arm. The first sound represents the systolic value and the last sound represents the diastolic blood pressure.
Why is hypertension called a ‘Silent killer’?
Hypertension does not produce any symptoms. Elevated blood pressures may be noticed during a routine health check up. So by the time you know that you are hypertensive, it may have caused significant damage to your systems.
Why is hypertension bad for us?
Hypertension is nat called a silent killer for nothing. Hypertension affects almost all organs of the body, causing permanent damage. Hypertension also acts in conjunction with other diseases like Diabetes to damage organs at a much faster pace than they would damage alone.
Heart is the most significantly affected organ from hypertension. Subjected to persistently elevated blood pressures, heart muscles increase in thickness but becomes less efficient, and eventually fail with time. Heart diseases including coronary artery disease and heart failures are the leading cause of death in hypertensive patients. Increased value of systolic blood pressure correlate more with risk of death from heart conditions. Aggressive control of blood pressures can reverse the changes to a certain extent.
Stroke is among the leading cause of deaths globally, and hypertension is the most significant risk factor for stroke. Elevated systolic blood pressures again correlate more with risk of stroke than diastolic blood pressures. Reducing blood pressures reduces risk of both ischaemic and hemorrhagic strokes.
Elevated blood pressure also leads to progressive, faster decline in cognitive functions as compared to non-hypertensive individuals.
Kidneys– The role of kidneys in hypertension is ironic. Kidney diseases are leading cause of secondary hypertension, and kidneys are key organs in regulating blood pressures. On the other hand, kidneys are a target for elevated blood pressures. Hypertension leads to progressive renal dysfunction by affecting small blood vessels on the kidney. Presence of small amount of albumin in the urine is an early marker for renal injury from hypertension.
Peripheral blood vessels- Stiffness of blood vessels is a factor causing elevated blood pressures. Blood pressure again leads to further changes in blood vessel walls making them more stiff and leading to blood flow obstruction. Restriction of blood flow to limbs causes pain while walking, and may eventually cause gangrene.
What are the key takeaways?
Prevention is certainly better than cure, but early detection to prevent further damage is equally important.
Get your blood pressures checked- Your age does not matter, start monitoring early, at least once a year.
Don’t ignore high blood pressure- If you come to know that your blood pressure is high on one recording or if you have a family history of hypertension, high levels of vigilance is required. Get your recordings frequently, or buy a home blood pressure monitoring unit.
Start medications early- If your multiple recordings are high, treatment directed at reducing your pressure below 140/90 mmHg should be started early to prevent damage to organs such as heart and kidneys.
Take medicine regularly- Your reading may stay low even if you skip your medication for a few days. Many drugs for reducing blood pressures are long acting and remain in your system for significantly long periods.
Disclaimer- This article is meant for only public awareness and can not substitute expert medical advice.