Hypertension and Its Consequences
INTRODUCTION
The blood pressure within a population is distributed in an asymmetrical curve as more
individuals have high blood pressure than low. Persistent increase in systemic arterial
blood pressure is known as hypertension.1 Clinically, a blood pressure of 160/95 mmHg
is deemed to be definitely hypertensive, and between 140/90 mmHg and 160/95 mmHg
is regarded as borderline.9
Blood pressure has a connection with ethnic group and sex, too. Blood pressure rises
with age, upto seventy years. This rise is more marked for systolic pressure and is more
prominent in men. Diastolic pressure may start to decline in the seventies.
Even moderate elevation of arterial blood pressure leads to shortened life expectancy. At
severely high mean arterial pressures, 50% or more above average, a person can expect to
live no more than a few years unless appropriately treated.2
Essential Hypertension
In about 95% of cases of high blood pressure the cause is unknown, and this condition is
referred to as “essential hypertension” or “primary hypertension”. It is treatable but
not curable.8 It is more common in adolescents.5, 6
Essential hypertension is of two types.13
1. Benign hypertension11
2. Malignant hypertension11
Benign hypertension
In early stages of this condition, there is a moderate increase in blood pressure. E.g.
200/100 mmHg. The blood pressure, especially the systolic, fluctuates considerably.
During sleep or emotional and physical rest, the blood pressure returns to normal level. In
stages of stress, the pressure rises to higher levels. Later there is further increase in blood
pressure and it doesn’t come back to normal level in resting conditions, too.
Malignant hypertension
This is also called accelerated hypertension. During this, the blood pressure is rapidly
elevated to a large extent of about 250/150 mmHg, much higher than the benign form.
This is always developed due to combined effect of primary and secondary hypertension.
Patients with malignant hypertension need immediate hospitalization and treatment. If
not treated, they can die within 6 to 12 months; however, normal life expectancy can be
restored with medical treatment unless the kidney is already impaired.
Recognized Causes
1. Genetic factors3,9
2. Foetal factors9
3. Environmental factors9
Genetic factors
Blood pressure levels tend to correlate within a family partly due to genetic factors.
Foetal factors
Studies have consistently shown a relationship between lower birth weight and
subsequent higher blood pressures. This relationship may be due to foetal adaptation in
intrauterine undernutrition with long term changes in blood vessel structure or in the
function of crucial hormonal systems.
Environmental factors
Obesity 9
Blood pressure is associated with overall body mass and more closely with central
obesity.
Alcohol9
Heavy alcohol intake (greater than 6 units per day) is associated with an increase in blood
pressure. Moderate drinking (2-3 units daily) does not appear to exert a pressure effect.
Electrolyte intake9
There’s a positive association between sodium intake and blood pressure, but negative
association between potassium intake and blood pressure. By combining the two into a
sodium-potassium ratio, a closer correlation has been observed.
Stress9
An acute major rise in blood pressure can be produced by acute pain, tension, or mental
stress, but it is much more difficult to show the chronic stress produces sustained
elevation of blood pressure.
Vegetarian diet
Vegetarians have lower blood pressures at all ages than omnivores. Increased intake of
fruits and vegetables has been shown to lower blood pressure in omnivore hypertensives.
One possibility is that an unsaturated vegetable fat lowers the blood pressure.
Insulin resistance9,12
An association between diabetes and hypertension has long been recognized, but more
recently a syndrome has been described of hyperinsulinaemia, glucose intolerance,
reduced levels of HDL cholesterol, hypertriglyceridaemia and central obesity (all of
which are related to insulin resistance) in association with hypertension.
Secondary Hypertension
In the remaining 5% of cases, high blood pressure is a symptom of a recognizable
underlying problem such as a kidney abnormality, endocrine disorder or medication.
When the root cause is corrected, blood pressure usually returns to normal. This
type of high blood pressure is called “secondary hypertension” because it is
hypertension caused by another disorder.
Some causes for secondary hypertension
Renal disorders
Renal artery stenosis
Chronic renal disease
Endocrine disorders9
Primary hyperaldosteronism
Hyper- or hypothyroidism
Pheochromocytoma
Cushing syndrome
Growth hormone hypersecretion
Cardiovascular disorders9
Aortic coarctation
Atherosclerosis
Neurogenic disorders
Pregnancy
Renal artery stenosis (renovascular disease)
Renal artery disease can cause of narrowing of the vessel lumen (stenosis). The
reduced lumen diameter increases the pressure drop along the length of the diseased
artery, which reduces the pressure at the afferent arteriole in the kidney. Reduced
arteriolar pressure and reduced renal perfusion stimulate renin release by the kidney.
This increases circulating angiotensin II and aldosterone. These hormones increase
blood volume by enhancing renal reabsorption of sodium and water. Increased
angiotensin II causes systemic vasoconstriction and enhances sympathetic activity.
Chronic elevation of angiotensin II promotes cardiac and vascular hypertrophy. The
net effect of these renal mechanisms is an increase in blood volume that augments
cardiac output by the Frank-Starling mechanism. Therefore, hypertension caused by
renal artery stenosis results from both an increase in systemic vascular resistance and
an increase in cardiac output.
Chronic renal disease
Any number of pathologic processes (e.g., diabetic nephropathy, glomerulonephritis)
can damage nephrons in the kidney. When this occurs, the kidney cannot excrete
normal amounts of sodium which leads to sodium and water retention, increased
blood volume, and increased cardiac output by the Frank-Starling mechanism. Renal
disease may also result in increased release of renin leading to a renin-dependent
form of hypertension. The elevation in arterial pressure secondary to renal disease
can be viewed as an attempt by the kidney to increase renal perfusion and restore
glomerular filtration.
Primary hyperaldosteronism (Conn’s syndrome)
Increased secretion of aldosterone generally results from adrenal adenoma or adrenal
hyperplasia. Increased circulating aldosterone causes renal retention of sodium and
water, so blood volume and arterial pressure increase. Plasma renin levels are
generally decreased as the body attempts to suppress the renin-angiotensin system;
there is also hypokalemia associated with the high levels of aldosterone.
Hyper- or hypothyroidism
Excessive thyroid hormone induces systemic vasoconstriction, an increase in blood
volume, and increased cardiac activity, all of which can lead to hypertension. It is
less clear why some patients with hypothyroidism develop hypertension, but it may
be related to decreased tissue metabolism reducing the release of vasodilator
metabolites, thereby producing vasoconstriction and increased systemic vascular
resistance.
Pheochromocytoma
Catecholamine secreting tumors in the adrenal medulla can lead to very high levels
of circulating catecholamines (both epinephrine and norepinephrine). This leads to
alpha-adrenoceptor mediated systemic vasoconstriction and beta-adrenoceptor
mediated cardiac stimulation, both of which contribute to significant elevations in
arterial pressure. Despite the elevation in arterial pressure, tachycardia occurs
because of the direct effects of the catecholamines on the heart and vasculature.
Excessive beta-adrenoceptor stimulation in the heart often leads to arrhythmias. The
pheochromocytoma is diagnosed by measuring plasma or urine catecholamine levels
and their metabolites (vanillylmandelic acid and metanephrine).
Cushing’s syndrome
Both adrenal glands can overproduce the hormone cortisol or it can arise in a benign or
malignant tumor. Hypertension results from the interplay of several pathophysiological
mechanisms regulating plasma volume, peripheral vascular resistance and cardiac output,
all of which may be increased. More than 80 percent of patients with Cushing’s syndrome
have hypertension.
Growth Hormone excess
Growth hormone induces sodium retention, thus increasing fluid volume and blood
pressure.
Aortic coarctation
Coarctation, or narrowing of the aorta (typically just distal to the left subclavian
artery), is a congenital defect that obstructs aortic outflow leading to elevated
pressures proximal to the coarctation (i.e., elevated arterial pressures in the head and
arms). Distal pressures, however, are not necessarily reduced as would be expected
from the hemodynamics associated with a stenosis. The reason for this is that
reduced systemic blood flow, and in particular reduced renal blood flow, leads to an
increase in the release of renin and an activation of the renin-angitensin-aldosteron
system.This in turn elevates blood volume and arterial pressure. Although the
aortic arch and carotid sinus baroreceptors are exposed to higher than normal
pressures, the baroreceptor reflex is blunted due to structural changes in the walls of
vessels where the baroreceptors are located. Also, baroreceptors become
desensitized to chronic elevation in pressure and become “reset” to the higher
pressure.
Pregnancy
Although few women of childbearing age have high blood pressure, up to 10% develop
hypertension of pregnancy. While generally benign, it may herald three complications of
pregnancy: pre-eclampsia, HELLP syndrome and eclampsia. Follow-up and control with
medication is therefore often necessary. Hypertension is very dangerous to pregnant
women and causes miscarriages
Hypertension Risk Factors
There are two types of factors that may place a person at increased risk for high blood
pressure:
1. Risk factors that are beyond control (predetermined)
2. Lifestyle or modifiable risk factors.
Predetermined Risk Factors
Some risk factors are beyond control. These include:
Family history: A person is more likely to develop high blood pressure if his parents
also had it.
Sex: Men are more likely to develop high blood pressure at a younger age than
women. Women are at a higher risk after age 60.
Age: High blood pressure generally occurs in people over 30 years old.
Race: African-Americans are at higher risk for developing high blood pressure, heart
disease, stroke and kidney failure.
Lifestyle Risk Factors
High blood pressure is often related to lifestyle factors.
The most common lifestyle factors that affect blood pressure are:
• Obesity
• Excess sodium (salt) in diet.
• Habitual alcohol use
• Smoking
• Exercise
• Use of certain medications, drugs, or other chemicals
• Anxiety or stress
• Agitation
• Pain
• Diabetes mellitus type1 and 11
• Other modifiable disorders - e.g. arteriosclerosis
Symptoms and signs
Hypertension has been described as “the silent killer” because it often occurs without
symptoms - indeed most people with high blood pressure don’t know they have it until
their blood pressure is checked. One out of four people with high blood pressure is
unaware of their condition.
There are symptoms associated with hypertension but by and large these symptoms are
not specific to high blood pressure.
These may include:
• headache (occasionally)
• tiredness
• confusion, anxiety
• vision changes
• nausea, vomiting
• excessive perspiration
• pale skin, or redness of the face or other areas
• muscle tremors
• angina-like pain: crushing substernal chest pain
• spleenomegaly
• nosebleeds
• heartbeat sensations e.g. palpitations
• ear noise/buzzing
• stroke
• congestive cardiac failure
Investigations commonly performed in newly diagnosed hypertension
Tests are undertaken to identify possible causes of secondary hypertension, and seek
evidence for end-organ damage to the heart itself or the eyes (retina) and kidneys.
Diabetes and raised cholesterol levels being additional risk factors for the development
of cardiovascular disease are also tested for as they will also require management.
Blood tests commonly performed include:
• Creatinine (renal function) - to identify both underlying renal disease as a cause of hypertension and conversely hypertension causing onset of kidney damage. Also a baseline for later monitoring the possible side-effects of certain antihypertensive drugs.
• Electrolytes (sodium, potassium)
• Glucose - to identify diabetes mellitus
• Cholesterol
Additional tests often include:
• Testing of urine samples for proteinuria – It is to pick up underlying kidney disease or evidence of hypertensive renal damage.
• Electrocardiogram (EKG/ECG) – It is for evidence of the heart being under strain from working against a high blood pressure. Also it may show left ventricular hypertrophy or of the occurrence of previous silent cardiac disease (either subtle electrical conduction disruption or even a myocardial infarction).
• Chest X-ray – It is to check for signs of cardiac enlargement or evidence of cardiac failure.
COMPLICATIONS
There are many serious complications that can result from hypertension - both life
threatening as well as seriously debilitating, which serves to underline the importance of
prevention and treatment of hypertension.
Some of the main ones include:
Heart
• heart attacks
• congestive heart failure
Blood vessels
• blood vessel damage (arteriosclerosis)
• hyaline degeneration
• aortic dissection (tearing of the aorta)
• micro- angiopathic haemolytic anaemia
Brain
• stroke
• brain damage (encephalopathy) 4
• Berry aneurysms
• cerebral thrombosis
• cerebral embolization
Eye
• impaired vision
Kidney
• kidney damage
Stroke and coronary heart disease.
Hypertension causes hardening of arterial walls, clot formation, atheroma and obstruction
of blood vessels, such as the aorta and the arteries supplying blood to the brain, heart,
kidneys and legs. Obstruction of blood flow in these vessels causes transient ischemic
attacks (sometimes called mini-strokes) in parts of the brain, heart attack, myocardial
infaction or pain in the leg muscles (due to poor blood supply to the legs).
Hypertension is considered an important risk factor for a type of irregular heart beat,
called atrial fibrillation, in the upper chambers of the heart. This condition is associated
with a three- to five-fold increase in the risk of strokes.
Left ventricular hypertrophy
Due to increased peripheral resistance, the heart must work hard to have enough cardiac
output to pump blood to every part of the body. This increased workload causes the
muscles of the left ventricle of the heart to become thicker. The enlarged left ventricle
requires more blood supply, but the coronary arteries may not provide enough blood
because they are narrowed, so the myocardium becomes ischaemic as well. It leads to left
ventricular failure. Failure also reduces left ventricular compliance in diastole, and the
maintenance of cardiac output may require higher filling pressure produced by increased
capacitance vessel tone. Thus, patients with this condition have more frequent heart
attacks and congestive heart failure.
Congestive cardiac failure
This may occur with little evidence of either previous or concurrent left ventricular
failure. Nevertheless there is almost always elevation of left ventricular end -diastolic
pressure and the pulmonary hypertension. The right ventricle dilates and systemic venous
pressure is elevated without the development of pulmonary oedema.
Vascular hypertrophy
Arteries and arterioles show hypertrophy as a response to the increased work load.
Hypertrophy occurs due to fibrous thickening of the tunica intima, duplicating of the
internal elastic lamina and hypertrophy of smooth muscle.
Atheroma
Atheromatous plaques occur in the arterial intima and consist of swelling of ground
substance, disintegration of elastic fibers and deposition of lipoproteins. Associated with
these changes there is atrophy of the overlying media. Thrombosis may occur as a sequel
to atheromatous change.
Hyaline degeneration
There is a patchy, hyaline eosinophilic thickening of the whole vessel wall beginning in
the sub endothelial region and extending to media. In a hypertensive person, arteriolar
compliance is reduced. This affects the barorecepter function and thus may impair the
circulatory reflexes.
Micro- angiopathic haemolytic anaemia
Malignant hypertension is usually associated with some evidence of intravascular
coagulation although in some patients, the changes may be minimal. There is haemolytic
anaemia, with deformed red cells, thrombocytopenia, fibrin degradation product in
plasma and urine and accelerated fibrinogen catabolism.
Aneurysm.
High blood pressure weakens the wall of the blood vessels, resulting in an aneurysm
especially in the brain and the aorta. Aneurysm breaks easily, potentially leading to
dangerous bleeding in the brain and the abdomen.
Brain damage (encephalopathy)
Hypertensive encephalopathy can result from elevation of blood pressure above the
autoregulatory range (which may extend upto a mean pressure of 150-200 mmHg in
hypertensive individuals). The focal breakdown of autoregulation causes areas of
vasodilatation with associated oedema. Despite the increase in local cerebral blood flow,
localized ischaemia and actual infarction may result, as well as petechial haemorrhages.
Berry aneurysms
These occur at the junction of extra cerebral vessels, where there is a developmental
absence of tunica media. They are the source of subarachnoid haemorrhage and occur
with increased frequency in polycystic renal disease, coarctation and hypertension.
Kidney damage.
Hypertension damages the kidneys by narrowing the main arteries supplying the kidneys
and damaging the small arteries within the kidneys. These effects lead to progressive loss
of kidney function and renal failure, eventually.
Impaired Vision
High blood pressure can eventually cause blood vessels in the eye to burst or bleed.
Vision may become blurred or otherwise impaired and can result in blindness.
MANAGING HYPERTENSION
Depending on the cause for the hypertension, treatment plan may include
lifestyle changes,
medication or a combination of both.
Lifestyle Changes
When high blood pressure is caused by lifestyle factors, the most effective way to control
it can be to change the behavior.
Achieve ideal body weight. Losing weight is the most effective non-clinical way
lowering the blood pressure. On average, a 10-pound weight loss will lower both
systolic and diastolic blood pressure measurement by about 5 mm Hg.
Restrict salt intake. It is recommended that healthy adults should have no more than
2400 mg of sodium or 1 1/4 teaspoons of salt per day.
• choose foods low in salt, such as fresh fruit and vegetables;
• avoid foods high in salt, such as processed meats, canned foods and snack foods;
• Avoid adding salt at the table, and minimize its use in cooking.
• Increase dietary potassium- Bananas, oranges, potatoes, tomatoes, milk, nuts, and cereals
Limit alcohol intake. Depending on the situation, fewer than three drinks or avoiding
alcohol completely is necessary.
Quit smoking. Smoking a cigarette can raise the blood pressure by 5 to 10 mm Hg
for about 30 minutes. It also greatly increases the risk of heart disease and stroke.
Exercise. Regular aerobic exercise and daily physical activity play a major role in the
prevention of high blood pressure, obesity, diabetes and heart disease. Aerobic
exercise involves continuous movement of the large muscle groups in the arms and
legs. These exercises benefit the heart by making it beat faster and more efficiently. If
performed daily, even moderate activities, such as gardening and housework, can
have long-term health benefits.
Relaxation therapy, such as meditation, that reduces environmental stress, high
sound levels and over-illumination can be an additional method of ameliorating
hypertension.
Blood Pressure Medication
There are five types of blood pressure medications, each made up of numerous
medicines. Each type acts in a different way to lower your blood pressure.
• Thiazides or Thiazide-like Diuretics10
• Angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers 10
• Alpha blockers, beta blockers, or combined alpha and beta blockers 10
• Calcium channel blockers 10.
• Vasodilators
Homeopathy14
Homeopathy may be useful as a supportive therapy.
Acupuncture14
Acupuncture may help reduce blood pressure and alleviate stress.
Massage14
Therapeutic massage may be effective in reducing the effects of stress, helping relaxation, and lowering blood pressure.