Hypertension

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Definition: Hypertension (HTN or HT), also known as high blood pressure or arterial 

hypertension; is a   chronic condition in which the blood pressure (BP) in the arteries is persistently elevated.

 

Normal Regulation of Blood Pressure:

·         Arterial blood pressure is directly proportionate to the product of the blood flow (cardiac output; CO) and the resistance to passage of blood through arterioles (peripheral vascular resistance; PVR), i.e. BP: is a pressure generated when the heart pumps the blood against the resistance of arterioles.

BP = Cardiac Output ( CO ) X Peripheral Vascular Resistance ( PVR )

Cardiac Output (CO): CO= Stroke Volume(SV) X Heart Rate(HR)

Stroke Volume (SV): is the volume of blood pumped from the left ventricle of the heart per beat.

Heart Rate (HR): is the speed of the heartbeat measured by the number of poundings of the heart per unit of time (typically beats per minute).

                 - Increase CO or PVR, or both à Increase BP.

                 - Decrease CO or PVR, or both à Decrease BP.

·         In both normal and hypertensive individuals , BP is maintained by moment-to-moment regulation of CO and PVR, through;

o   Neural Mechanisms : baroreceptors and autonomic nervous system .

o   Renal Mechanisms : renin-angiotensin-aldosterone system and aldosterone.

o   Local Endothelium Derived Factors : nitric oxide (vasodilator) and endothelin (vasoconstrictor).

o   Other Hormones : e.g.; natriuretic peptides, vasopressin & kallikrein-Kinin system.

 

Uncontrolled Hypertension Effects on the Body:

Arteries Damage   - Artery walls thick and stiff (arteriosclerosis)

                                  - Cause, angina (chest pain), heart attack, heart failure, kidney failure, stroke,   

                                    blocked arteries in legs or arms ( peripheral artery disease ) and eye damage.

Heart Damage        - Uncontrolled high blood pressure can damage the heart in a number of ways, such

                                    as coronary artery disease, enlarged left heart (left ventricular hypertrophy) and

                                    heart failure ( heart muscle weakness and work less efficiently).

Kidneys Damage   - Uncontrolled high blood pressure can injure renal blood vessels and leading  

                                    nephropathy

                                 - Cause, weakens and damages the artery wall lead to kidney failure.

                                 - Diabetes in addition to high blood pressure can worsen the damage.

Eye Damage     - Cause, Hypertensive Retinopathy:

o   Damage in the arterial and arteriolar circulation in response to the high blood pressure.

Brain Damage  - Stroke , due to damaging and weakening brain blood vessels.

                            - Dementia ; due to narrowing and blockage of the arteries that supply blood to the brain

 

Some of Medical Terms:-

·         Systolic Blood Pressure (SBP): is the top number, the highest pressure when the heart pushes the blood into the body.

·         Diastolic Blood Pressure (DBP): is the bottom number, the lowest pressure when the heart relaxes between beats.

·         Mean Arterial Pressure (MAP): is the average over a cardiac cycle and is determined by the cardiac output , systemic vascular resistance and central venous pressure.

 

Normal Resting Blood Pressure by Age:

Blood Pressure Value	Male Age (year)			Female Age (year)
	10-15	20-30	50-60	10-15	20-30	50-60
Systolic blood pressure SBP (mmHg)	100	120	134	84	120	130
Diastolic blood pressure DBP(mmHg )	60	80	84	40	74	84
Mean arterial pressure MAP(mmHg)	73	93	97	55	88	92

 

classification of hypertension defined by the American Heart Association:-

Blood Pressure Category	Systolic (mm Hg)	Diastolic (mm Hg)	Follow-up
Normal	Less than 120	Less than 80	Recheck once every 2 years
High-normal (Prehypertension)	120-139	80-89	Recheck once every 1 year
Stage 1	140-159	90-99	Confirm within 2 months
Stage 2	160 or higher	100 or higher	Healthcare provider within a month
Hypertensive Crisis	Higher than 180	Higher than 110	Emergency care needed

 

 

Classification hypertension defined by cause:-

·         Primary (Essential or Idiopathic) Hypertension:

v  The majority of cases about 95%.

v  No specific medical causes.

v  Unknown etiology but multiple factors may contribute to the development of primary hypertension including:

-         Smoking, obesity, stressful lifestyle, high dietary intake of sodium, family story and alcohol intake.

-         Overactive of renin-angiotensin system or sympathetic nervous system.

-         Deficiency in the local synthesis of vasodilating substances (NO, bradykinin and prostacyclin) or excess vasoconstricting substances (angiotensin II and endothelin ).

-         Insulin resistance, hyperinsulinemia and obesity, also linked with renin-angiotensin system.

-         Vitamin D deficiency may leads to an increase in renin secretion.

v  Prevalence of essential hypertension increases with age.

·         Secondary Hypertension :

v  Few cases about 5%

v  Most of these are caused by:

1.       Chronic kidney disease or renovascular disease .

2.       Primary aldosteronism (Conn's syndrome) & hypercortisolism (Cushing's syndrome).

3.       Pheochromocytoma and hyperthyroidism.

4.       Drugs that may increase BP include:

-         Corticosteroids, Estrogens, NSAIDs and Amphetamines.

 

 

 

Causes of Hypertension :

Nature causes	Chemical causes
- Genetics. - Salt sensitivity. - Obstructive sleep apnea (OSA). - Insulin resistance and hyperinsulinemia. - Stressful situations, obesity, smoking and other    lifestyle. - Kidney problems. - Endocrine causes: v  Primary aldosteronism.  v  Pheochromocytoma.  v  Hyperthyroidism.  v  Cushing's syndrome.	- Salts. - Alcohol. - Oral contraceptives. - NSAIDs. - Glycyrrhiza glabra (Liquorice). - Decongestants. - Antidepressants. - Sympathomimetics. - Many industrial chemical. - Corticosteroids. - Ergotamine alkaloids. - Cyclosporine (Immunosuppressant drug). - Cocaine. - Caffeine.

 

 

 

 

Clinical Presentation:-

·         Patients with uncomplicated primary hypertension are usually asymptomatic initially.

·         Patients with secondary hypertension may have symptoms suggestive of the underly disorder;

                    - Pheochromocytoma, sweating , tachycardia and palpitations.

                    - Primary aldosteronism; hypokalemia symptoms (muscle cramps & weakness).

                    - Cushing's syndrome; weight gain, polyuria, edema, moon face and buffalo hump.

Hypertension Risk Factors:-

      Risk factors that can be controlled are :

§  High cholesterol level. 

§  Tobacco use (Smoking).

§  Diabetes mellitus. 

§  Overweight and obesity.

§  Physical inactivity. 

§  High salt intake.

§  Coarctation of the aorta. 

§  Sleep apnea.

      Risk factors beyond our control are:

§  Age.

§  Family history of heart disease.

 

 

Diagnose of Hypertension:-

- Diagnosis of hypertension should be based on the average of two or more readings taken at each of two or more clinical encounters.

- Hypertension progress may lead to serious complications, some of clinical diagnosis is needed:

§  Funduscopic examination (examination of the eye). 

§  Cardiopulmonary examination.

§  Peripheral vascular examination.

§  Laboratory tests;

v  Plasma electrolytes, hypokalemia may suggest primary aldosteronism.

v  Urine analysis: protein , blood cells and casts in the urine may indicate renovascular disease.

v  Blood urea nitrogen (BUN) to creatinine ratio and glomerular filtration rate ( GRF ) also be obtained.

v  Lipid profile and blood glucose level.

v  Plasma norepinephrine and urinary metanephrine or vanillylmandelic acid (VMA) level for pheochromocytoma.

v  Plasma and urinary aldosterone level for primary aldosteronism.

Treatment of Hypertension:

Lifestyle Modification (Non-pharmacologic treatment)	Medications (Antihypertensive drugs)
- DASH eating plan (See below). - Dietary sodium (salt) restriction. - Weight loss. - Regular aerobic physical activity. - Smoking cessation. - Moderate alcohol consumption. - Reduction of environmental stressors. *   Lifestyle modification alone is effective for      most patients with prehypertension, but is      insufficient alone for patients with      hypertension.	- Diuretics. - β-blockers. - ACE Inhibitors (ACEIs). - Angiotensin receptor blockers (ARBs). - Direct Renin inhibitors. - α-blockers. - Calcium channel blockers (CCBs). - Centrally-acting sympathetic inhibitors. - Peripherally-acting sympathetic inhibitors. - Ganglionic blockers. - Vasodilators. - Antihypertensive of natural sources.

 

Dietary Approaches to Stop Hypertension ( DASH ) eating plan:

·         Is a diet that is low in; Saturated fats and cholesterol.

·         It encourages fewer servings of; Limits sodium (2,300 mg of sodium a day). sweets, sugary beverages and red meats.

·         It also includes: Vegetables, fruits, and fat-free or low-fat dairy products.

·         It is rich in: Magnesium, potassium, calcium, as well as proteins and fibers.