Last Updated on September 24, 2023
Hypertension or high blood pressure is a condition in which the arteries have persistently elevated blood pressure. Hypertension (high blood pressure) is when the pressure in your blood vessels is too high (140/90 mmHg or higher)
Blood pressure is the force of blood pushing up against the blood vessel walls. Higher blood pressure means that the heart is pumping harder.
Untreated, hypertension can lead to damage of various organs such as the retina, kidney, and heart and can rupture the vessels leading to aneurysms or strikes.
Hypertension is the most important modifiable risk factor [the risk factor that can be modified or controlled
- Heart disease
- Stroke
- Congestive heart failure
- End-stage renal disease
- Peripheral vascular disease
Thus it becomes very important to recognize and treat the disease at the earliest.
High blood pressure is common but with treatment can be controlled to lead a healthy life.
Hypertension is a silent disease. That means people with high blood pressure do not have any symptoms. Thus, the only way to know about its value is to get it checked. A sphygmomanometer is an instrument that is used to check blood pressure.
Digital blood pressure monitors are also available.
People with high blood pressure may not feel symptoms. The only way to know is to get your blood pressure checked.
Older age, family history, obesity, physical inactivity, and a high salt diet are frequent risk factors for high BP.
How is Blood Pressure Measured
Blood pressure can be measured using a sphygmomanometer or digital measuring devices. It is written as two values separated by a slash.
- The first value is systolic blood pressure which represents the pressure in blood vessels when the heart contracts or beats.
- The second (diastolic) number represents the pressure in the vessels when the heart rests between beats.
The normal level for blood pressure is below 120/80, where 120 represents the systolic measurement and 80 represents the diastolic measurement.
Types of Hypertension
Hypertension is mainly of two types – primary and secondary.
Essential hypertension
This type is the most common type of high blood pressure and the cause is not known cause.
Secondary hypertension
It is the term for high blood pressure with a known cause, such as renal disease, or tumors.
Primary and secondary hypertension may sometimes coexist.
Approximately 90-95% of adults with hypertension have primary hypertension and 5-10% of the cases are of secondary hypertension.
Other Types
Labile hypertension
It is said to be present when the patient is hypertensive at one time and normotensive at another time.
Malignant hypertension
High blood pressure is associated with complications like papilledema, retinal exudates, and hemorrhage. No absolute BP level can be assigned for this condition. However, these patients usually have BP around 200/140 mmHg.
Hypertension in Pregnancy
High blood pressure may occur in pregnancy in otherwise normotensive females. Similarly, hypertension may worsen in women with preexisting hypertension and may develop other complications like decreased renal function.
The condition often reverses after the delivery. These patients need to be extra monitored throughout the pregnancy.
Preeclampsia is the term given to the condition when high blood pressure in pregnancy leads to renal and urine problems, lung edema, and visual problems. Preeclampsia can be dangerous to mother and baby.
Risk Factors Associated with Hypertension
The exact causes of hypertension are unknown but several factors have been found associated. These are
- Smoking
- Obesity or being overweight
- Being obese/overweight as a child
- Diabetes
- Sedentary lifestyle
- High salt intake
- High levels of alcohol consumption
- Stress
- Aging
- Medications such as oral contraceptives
- Family history of hypertension
- Diabetes
- Chronic renal disease
- Adrenal and thyroid tumors
- Sleep Apnoea
Known Causes of Secondary Hypertension
- Renal Causes
- Nephritis
- Polycystic kidneys
- Renal artery stenosis
- Chronic kidney disease
- Renin-producing tumor
- Liddle syndrome
- Vascular Causes
- Arteriosclerosis
- Coarctation of aorta
- Endocrinal Causes
- Pheochromocytoma
- Cushing’s syndrome
- Thyrotoxicosis, myxedema
- Primary hyperaldosteronism
- Congenital adrenal hyperplasia
- Neurological
- Raised intracranial tension
- Lead encephalopathy
- Sleep apnoea
- Brain tumor
- Miscellaneous
- Polycythemia
- Aortic incompetence
- Hypertension in pregnancy
- Periarteritis nodosa
- Alcohol
- Drugs
- Corticosteroids
- Cocaine
- Cyclosporine
- NSAIDs
- Tacrolimus
- Adrenergic formulations
- Decongestants containing ephedrine
Pathophysiology of Hypertension
The pathogenesis of essential hypertension and the exact mechanisms underlying essential hypertension have not been established.
Over the period, essential hypertension evolves from occasional to established hypertension to complicated hypertension [with end-organ damage to the vessels, heart, kidneys, retina, and central nervous system].
What are the Effects of Hypertension on Body
The common organs damaged by long-standing uncontrolled hypertension are the heart, kidneys, blood vessels, retina, and central nervous system. Effects are seen in uncontrolled high blood pressure over the years.
Damage to Arteries
Arteries are healthy when they are flexible and adapt to different body requirements of blood varying under different circumstances.
Long-standing hypertension makes arteries stiff and contracted. This allows atherosclerosis to occur more readily than otherwise. Atherosclerosis is the deposition of fatty plaque inside the arteries causing the lumen to narrow and restrict blood flow.
Thus further increase in blood pressure is required for passage of the blood. Blood vessels can get blocked and eventually, blood supply may fail to critical organs leading to stroke or heart attack.
This damage can lead to increased blood pressure, blockages, and, eventually, heart attack and stroke.
Damage to the Heart
Because of increased blood pressure heart needs to work extra. The heart’s muscles [cardica muscles] need to pump with greater force and greater frequency.
This leads to increased risk for the following:
- Cardiomyopathy [heart enlargement]
- Heart failure
- Arrhythmias [irregular heartbeat]
- Heart attack
Damage to Brain
The blood supply of the brain may be affected leading to
- Cerebral hemorrhage
- Cerebral thrombosis
- Cerebral embolism
- Infarction
- Hypertensive encephalopathy.
Clinically, these manifest as either transient ischemic attacks or stroke.
Stroke can cause serious disabilities in speech, movement, and other basic activities. A stroke can also kill you.
Poor cognitive functions have also been linked to having high blood pressure.
Kidneys
The blood flow to the kidneys may decrease due to progressive arteriosclerosis of renal arterioles leading to a compromise of renal function and
- Shrinkage of kidney
- Proteinuria.
Eye Changes
- Graduated changes may occur in the fundus corresponding to the severity of hypertension
- Papilledema.
Therefore, it becomes quite important to recognize hypertension early and follow measures to control it
Symptoms of Hypertension
Hypertension is a silent disease and there are no specific symptoms associated. In fact, many persons with high blood pressure are not even aware that they have this condition.
However, extremely high blood pressure may lead to some symptoms like
- Headaches
- Dizziness
- Nausea
- Vision problems
- Breathing troubles
- Irregular heartbeat
- epistaxis
- Blood in the urine.
These clinical features may be due to the elevated blood pressure itself, target organ involvement or due to underlying disease, as in secondary hypertension.
Very often one is found to be hypertensive in routine health checkups or when under treatment for some other ailment and vitals are taken.
Hypertension can be diagnosed simply by measuring the blood pressure with a device called a sphygmomanometer which consists of an arm cuff, dial, pump, and valve. Digital devices for measuring blood pressure are available.
The measurement of blood pressure involves recording systolic and diastolic values.
Depending on these readings, a person may have
- Normal blood pressure– Blood pressure is 120/80 mm Hg or lower
- Elevated blood pressure– Systolic 120 to 129 mm Hg and Diastolic less than 80 mm Hg
- Stage 1 hypertension– Systolic – 130 to 139 mm Hg, diastolic- 80-89 mm Hg
- Stage 2 hypertension – Systolic 140 mm Hg or higher diastolic 90 mm Hg or higher
- Hypertensive Emergency– Blood pressure values higher than 180/120 mm Hg
A hypertensive emergency requires immediate medical help.
A person is labeled hypertensive which is confirmed after elevated blood pressure is found on at least three separate occasions
Recent activity or stress may result in erroneous readings and regular monitoring may be required before labeling someone as hypertensive.
A detailed history and examination is done to understand should extract the following information:
- Extent of end-organ damage
- Cardiovascular risk assessment
- Tobacco use
- Increased LDL
- Obesity
- Age>
- 55 years for men
- 65 years for women
- Family history
- Sedentary lifestyle
- Exclusion of secondary causes of hypertension
Patients may have undiagnosed hypertension for years without having had their BP checked. Therefore, a careful history of end-organ damage should be obtained.
Obtain a history of the patient’s use of over-the-counter medications
At-home ambulatory blood pressure monitoring correlates better with the risk of end-organ damage and cardiovascular risk.
Diagnostic Workup
Baseline Evaluation
- Urinalysis
- Fasting blood glucose
- HbA1c in preexisting diabetics
- Hematocrit and CBC
- Serum sodium and potassium
- Serum Creatinine
- Lipid profile
When required, tests such as electrocardiograms and echocardiograms can be done to check the heart condition.
Blood investigations to identify possible causes of secondary hypertension should be done when a secondary cause needs to be ruled out.
In addition, if long-standing undiagnosed hypertension is suspected, investigations to look for end-organ disease can be undertaken. these are generally
- Chest x-ray
- Urine microalbumin.
- Microalbuminuria is an early indicator of diabetic nephropathy
- Also a marker for a higher risk of cardiovascular disease
- All individuals with type I diabetes should be screened for microalbuminuria
Specific tests for different causes of secondary causes may be done as required.
Treatment of Hypertension
Treatment of hypertension aims to lower the blood pressure to less than 130/90 or even lower.
In patients older than 60 years some recommendations are fine with BP less than 140/90
The treatment involves lifestyle changes and drugs.
Adults with stage 1 hypertension should be first put on a non-drug treatment regime that includes lifestyle changes and exercise. They should be evaluated on a monthly basis to see the effect.
Adults with higher initial blood pressure should be put on drug treatment along with lifestyle changes.
Treatment of hypertension is multipronged and complex. Along with blood pressure, the aim is also to reduce the risk of end-organ disease.
The presence of comorbidities further complicates the situation
So additional recommendations do exist.
Some of them as per the American Association of Clinical Endocrinologists/American College of Endocrinology (AACE/ACE) are
- LDL levels in various risk profiles for cardiovascular events
- < 55 mg/dL in extreme risk
- < 70 mg/dL in very high risk
- < 100 mg/dL for individuals with high/moderate risk
- <130 mg/dL for low risk
- Cholesterol
- <180 mg/dL
Those not meeting the targets need to be put on statin treatment, drugs that manage lipid levels.
Lifestyle Changes
These help to control hypertension in some but are useful as adjuvants to drug treatment in almost all patients. They include the following measures:
Salt reduction
A modest salt restriction is effective in controlling mild to moderate hypertension because sodium and water retention is involved in a large proportion of hypertensives. The recommended level is 6 g NaCl per day.
Weight reduction
Losing weight decreases blood pressure and modifies other cardiovascular risk factors like diabetes and dyslipidemia.
Physical Activity
Physical activity benefits in more than one way. Not only it reduces blood pressure but also the risk of diabetes and improves cardiovascular health. For adults recommended is 150-300 minutes per week of moderate-intensity or 75-150 minutes of vigorous-intensity aerobic physical activity.
No Smoking
Smoking acutely raises BP. In addition, it is an independent and most important reversible coronary risk factor. Since tolerance develops to nicotine-induced hemodynamic effects, chronic smoking may not be associated with high BP. All hypertensives must be advised to stop smoking.
Relaxation
Various forms of relaxation can help to lower blood pressure, especially in cases where sympathetic activity is increased
- Yoga
- Biofeedback
- Psychotherapy
Alcohol Reduction
Not more than 1-2 standard drinks per day.
Dietary Changes
Potassium, calcium, and magnesium consumption help to decrease blood pressure whereas lower intake of these potentiates the effect of sodium. Lower intake of these elements potentiates the effect of sodium on BP.
- A diet rich in milk and vegetables
- A high intake of polyunsaturated fish oils
- Foods rich in potassium [vegetables]
- Increased sodium excretion
- Decreased sympathetic activity
- Decreased rennin-angiotensin secretion
- Direct dilatation of renal arteries
- Reduced salt intake
DASH Diet
DASH stands for a dietary approach to stop hypertension. It is an eating plan that is low in fat but rich in low-fat dairy foods, fruits, and vegetables. Apart from providing benefits for high blood pressure, it is also claimed to reduce stroke and cardiac disease risk.
Green Vegetables Are Part Of DASH. Whole grains, fish, poultry, nuts, seeds, and dried beans are recommended as a part of a balanced diet.
Generally speaking, the DASH diet is a kind of vegetarian diet low in sodium, and fat and rich in potassium, calcium, and magnesium.
DASH diet has been found to reduce BP by 8-4 mm.
Drugs Treatment for Hypertension
If lifestyle modifications are not able to control blood pressure sufficiently or the patient has high blood pressure on initial evaluation, drug treatment should be initiated.
The following drugs are used for the treatment of high blood pressure
- Diuretics
- Angiotensin-converting enzyme inhibitors
- angiotensin receptor blockers
- calcium channel blockers
- Beta-blockers
It is estimated that more than half of the patients require more than one drug especially those in stage 2.
Some drugs act better in certain situations. Recommended drugs to choose from in various scenarios of hypertension are
- Heart failure
- Diuretic
- Beta-blocker
- ACE Inhibitors
- Angiotensin Receptor blockers
- Aldosterone antagonist
- Following Myocardial Infarction
- Beta-blocker
- ACE inhibitor
- Diabetes
- ACE Inhibitors
- Angiotensin Receptor blockers
- Chronic kidney disease
- ACE Inhibitors
- Angiotensin Receptor blockers
Diuretics
Diuretics are named so because they induce diuresis or increased formation of urine. Diuretics increase the production of urine and decrease fluid volume. Oral diuretics are the most widely used antihypertensive agents.
Depending on the mechanism of action, there are many types of diuretics that can be used as antihypertensive drugs.
Thiazide Diuretics
- Inhibit reabsorption of sodium and chloride mostly in the distal tubules of the nephron in the kidney
- Also, increase potassium and bicarbonate excretion
- Decrease calcium and uric acid excretion
- Thiazides do not affect normal blood pressure.
- Act by reducing extra-cellular fluid volume and cardiac output
- Adverse effects]
- Low sodium or hyponatremia.
- Low potassium or hypokalemia
- Hyperlipidemia and hyperuricemia
- Decreased magnesium or hypomagnesemia
- Suppress insulin release due to hypokalemia may occur.
Hydrochlorothiazide, Chlorthalidone, Metolazone and indapamide are various thiazied diuretic drughs
Potassium-Sparing Diuretics
- Interfere with sodium reabsorption at the distal tubule part of the nephron [structural unit of kidney]
- Decreasing potassium secretion
- Weak diuretic effect
- Weak antihypertensive effect if used alone.
Triamterene and amiloride are commonly used drugs.
Loop Diuretics
- Act on the ascending limb of the loop of Henle of the nephron
- Commonly used to control volume retention.
- Prescribed esp in cases with decreased glomerular filtration rate or heart failure.
- Not very effective alone
Furosemide, torsemide, and bumetanide are commonly used drugs.
ACE Inhibitors
Renin released from the kidney acts on circulating angiotensinogen to produce angiotensin I which is converted to angiotensin II by converting enzyme. Angiotensin II is a strong constrictor of the vessels. It also stimulates aldosterone which retains sodium and causes hypertension.
ACE inhibitors act by inhibiting the converting enzyme preventing the formation of angiotensin II and lower BP. They also decrease the degradation of bradykinin, a strong dilator of blood vessels [dilatation of vessels lowers blood pressure].
ACE inhibitors also decrease ventricular hypertrophy and arrhythmia due to reperfusion injury. These also decrease microalbuminuria. They are preferred drugs in chronic kidney disease and proteinuria.
ACE Inhibitors are useful in renovascular hypertension. High angiotensin II is however required to maintain adequate filtration pressure behind the stenotic lesion. ACE Inhibitors decrease the perfusion pressure and lead to azotemia. Thus, they are contraindicated in bilateral renal artery stenosis. These drugs are useful in hypertensive diabetics because of their neutral effect on carbohydrate metabolism.
Fosinopril, captopril, Ramipril, enalapril, lisinopril, and quinapril are commonly used drugs.
Angiotensin Receptor Blockers
These are indicated in people who cannot tolerate ACE inhibitors
These drugs bind to angiotensin type I (AT1) receptors and thus block the binding of Angiotensin II to them. This reduces the effects of angiotensin like vasoconstriction, sodium retention, and aldosterone release. These are contraindicated in pregnancy.
Losartan, valsartan, olmesartan, eprosartan, azilsartan are commonly used drugs.
Beta-Blockers
This group of drugs is not recommended as first-line drugs. They offer, however, a better choice when a condition like heart failure, myocardial infarction, or diabetes is present. S
They should be cautiously used in cases with asthma and obstructive lung disease.
Atenolol, metoprolol, propranolol, bisoprolol, and timolol are the usual drugs
Beta-blockers with additional alpha receptor blockages like labetalol and carvedilol also cause peripheral vessel dilatation.
Acebutolol and pindolol possess intrinsic sympathomimetic activity. That means they tend to oppose the stimulating effects of catecholamines.
Calcium Channel Blockers
There are two kinds of drugs in this group
- Dihydropyridines
- Act on the vascular smooth muscle
- Cause vasodilatation and a decrease in blood pressure
- Examples include amlodipine, nifedipine, clevidipine, and felodipine
- Non-dihydropyridines
- Act on the SA node and AV node of the heart too
- Depressant effects on the heart with lesser amounts of peripheral vasodilation
- Verapamil and diltiazem calcium blockers. These drugs are especially useful in elderly hypertensives.
Flushing, headache, palpitations, edema, and hypotension may occur as side effects.
Alpha-Blockers
Adrenergic stimulation of alpha-1 receptors in the vascular smooth muscles causes vasoconstriction and hypertension. Alpha-blockers attenuate vasoconstriction, and thereby decrease vascular resistance and blood pressure. Prazosin was the first alpha-blocker with a short duration of action. Terazosin and doxazosin are longer-acting once-a-day alpha-blockers. The efficacy can be enhanced by the concomitant use of diuretics.
The most dramatic adverse effect is the first dose of postural hypotension/syncope.
Vasodilators
These drugs act on the arteriolar smooth muscles, causing vasodilatation and lowering BP. Hydralazine and minoxidil are commonly used vasodilators. Diazoxide and nitroprusside are parenteral vasodilators useful in hypertensive emergencies.
Other Antihypertensive Drugs
- Selective aldosterone antagonists
- Compete with aldosterone receptor sites
- Decrease blood pressure and sodium reabsorption
- Eplerenone,spironolactone
- Centrally acting alpha2-agonists
- Stimulate presynaptic alpha2-adrenergic receptors in the brain stem
- This leads to a reduction in sympathetic nervous activity
- Methyldopa, clonidine. guanfacine
- Renin Inhibitors
- Reserpine
Surgery
Surgery for hypertension is usually not needed. However, surgery may be considered for lesion removal like pheochromocytoma or adenoma that produces aldosterone. In cases with renal artery disease, angioplasty is quite successful.
Prognosis
Untreated, most of the people who are diagnosed with hypertension continue to have increasing blood pressure over the years. Untreated hypertension increases the risk of atherosclerotic disease and organ damage within 8-10 years after onset.
Death from ischemic heart disease or stroke increases progressively as blood pressure increases.
A long-term commitment to lifestyle modifications and drug therapy is required.
Prevention of High Blood Pressure
Lifestyle changes
- Healthy Dietary Habits
- Less salt
- More vegetables and fruits.
- Avoid high-fat diet
- Physically active
- Avoid prolonged sitting
- Include physical activity in your routine like walking, running, swimming, and lifting weights.
- Minimum 150 minutes of physical activity per week
- Lose weight
- Quit smoking
- Moderate alcohol intake
- Tackle stress
- Monitor and treat BP if required
References
- Matthew R. Alexander. Nov 9, 2022. Hypertension. Medscape.Accessed on 23 Sep 2023 <https://emedicine.medscape.com/article/241381-overview> Link
- Weber MA, Schiffrin EL, White WB, et al. Clinical practice guidelines for the management of hypertension in the community a statement by the American Society of Hypertension and the International Society of Hypertension. J Hypertens. 2014 Jan. 32 (1):3-15.
- Narkiewicz K. Diagnosis and management of hypertension in obesity. Obes Rev. 2006 May. 7(2):155-62.
- Ott C, Schmieder RE. Diagnosis and treatment of arterial hypertension 2021. Kidney Int. 2022 Jan;101(1):36-46. doi: 10.1016/j.kint.2021.09.026