Clinical epidemiology and consequences of having high blood pressure

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Clinical epidemiology and consequences of having
high blood pressure

• Ivo Ricardo de Seabra Rodrigues Dias

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What is hypertension?

• Hypertension (HT), or high blood pressure, is a
  condition in which blood pressure is persistently
  elevated, that is, it maintains itself at high
  levels during a long period of time
• NOT to be confused with elevated blood pressure
  just after a stressful situation or exercise, for
  example

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Hypertension (HT) facts I

• Higher incidence of HT in Western society
• According to the Blood Pressure Association, as
  blood pressure rises with age, about half of all
  people over the age of 75 and about one quarter
  of all middle-aged people have HT
• 41 of men and 33 of women in the UK suffer from
  HT almost 80 of these men and 70 of these
  women are NOT GETTING TREATMENT

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Hypertension (HT) facts II

• Doctors call HT the silent killer because it can
  exist with no obvious symptoms
• Undiagnosed HT leads to potentially
  life-threatening health problems
• Youre most likely to develop HT after age 30
• In the absence of high blood pressure symptoms,
  HT is diagnosed based on several blood pressure
  readings taken over a period of time

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Blood pressure table for HT
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Two main types of HT

• Essential HT 95 of individuals with HT suffer
  from this form it is of unknown origin
• Secondary HT 5 of individuals with HT suffer
  from this it is called secondary HT because it
  has at its origin usually a physical cause

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Secondary HT I

• Volume-loading HT caused by excess accumulation
  of extracellular fluid in the body
• HT caused by Primary Aldosteronism
• caused by excess aldosterone or other types of
  steroids in the body Primary Aldosteronism is a
  small tumor in one of the adrenal glands that
  causes the secretion of large quantities of
  aldosterone, which in turn increases the rate of
  salt and water reabsorption thereby increasing
  the extracellular fluid volume

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Secondary HT II

• Types of HT in which Angiotensin is involved
• Hypertension caused by a Renin-Secretin Tumor or
  by Infusion of Angiotensin II
• Sometimes a tumor of the renin-secretin
  juxtaglomerular cells occurs that secretes
  enormous amounts of renin, which, in turn, equals
  large amounts of angiotensin II
• One-Kidney Goldblatt HT
• One kidney is removed and a constrictor is placed
  on the renal artery of the remaining kidney this
  triggers renin release
• Named after Dr. Goldblatt

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Secondary HT III

• Two-Kidney Goldblatt HT
• When the artery to one kidney is constricted
  while the artery to the other kidney is normal,
  the constricted kidney retains salt and water
  because of decreased renal arterial pressure and
  the normal kidney retains salt and water because
  of renin produced by the ischemic kidney both
  kidneys become salt and water retainers
• HT caused by diseased kidneys that secrete renin
  chronically
• Patchy areas of one or both kidneys are diseased
  and become ischemic because of local vascular
  constrictions similar to two-kidney Goldblatt HT

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Secondary HT IV

• Other types of HT caused by combinations of
  volume-loading and vasoconstriction
• HT in the upper part of the body caused by
  coarctation of the aorta
• When this occurs, blood flow to the lower body is
  carried by multiple small collateral arteries in
  the body wall, with much vascular resistance
  between the upper aorta and the lower aorta thus
  having an arterial pressure in the upper part of
  the body that is about 55 higher than that in
  the lower body

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Secondary HT V

• HT in Toxemia of Pregnancy
• HT is one of the manifestations of the syndrome
  toxemia of pregnancy it is believed there is a
  thickening of the kidney glomerular membranes,
  which reduces the rate of fluid filtration to
  resume the normal filtration rate, the arterial
  pressure level must be increased
• Neurogenic HT
• Acute HT can be caused by strong stimulation of
  the sympathetic nervous system (ex. stress,
  anxiety) when the sympathetic system becomes
  excessively stimulated, peripheral
  vasoconstriction occurs everywhere in the body

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Secondary HT VI

• Malignant HT
• Occurs when a sudden and dangerously high rise in
  blood pressure occurs
• Symptoms chest pain, blurred vision, headaches,
  numbness, seizures, sudden confusion
• This disorder can be life threatening, as
  multiple organs can be damaged by the sudden rise
  in pressure
• Usually strikes people with previous histories of
  HT, particularly secondary HT due to kidney
  diseases

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Secondary HT VII

• Pulmonary HT
• Often caused by heart and lung diseases but can
  occur due to HIV infection or intravenous drug
  use
• High blood pressure only in the arteries that
  enter the lungs while the rest of the body is at
  normal or even low blood pressure
• Portal HT
• Caused by liver disease (ex. cirrhosis)
• Creates varicose veins at the upper part of the
  stomach, which can rupture

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Essential HT I

• Contributors to HT
• Excessive weight
• Lack of physical activity
• Excessive salt intake
• Diets high in fat and cholesterol
• Alcohol consumption
• Smoking
• Stress
• Genetics
• Race (ex. African-Americans suffer more from HT
  than white Americans)
• Gender (males are more likely to develop HT)

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Essential HT II

• Many of the risk factors vary from individual to
  individual (ex. some people thrive under stress
  levels that cripple others)
• Some characteristics of severe essential HT
• The mean arterial pressure is increased 40 to
  60
• In the late, more severe stages, the renal blood
  flow is decreased to about one half normal
• Resistance to blood flow through the kidneys is
  increased twofold to fourfold
• Despite the decrease in renal blood flow, the
  glomerular filtration rate is often near normal
• The cardiac output is about normal
• Total peripheral resistance is increased about
  40 to 60
• Kidneys will not excrete adequate amounts of salt
  and water unless arterial pressure is high
  (reason for this is unknown)

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Treatment for HT

• Secondary HT can be treated by curing the disease
  responsible for this type of HT
• Treatment of Essential HT varies from person to
  person
• For a mild case of HT, treatment might include
  stopping smoking, cutting down on alcohol, lose
  weight and/or exercise
• For more severe cases, a variety of medications
  are also used to combat HT

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Consequences of HT

• If left untreated, HT can result in
• Shortened life expectancy (no more than a few
  years at severely high pressures)
• Excess workload on the heart leads to early heart
  failure and coronary heart disease
• Clogged arteries
• The high pressure frequently ruptures a major
  blood vessel in the brain, followed by death of
  major portions of the brain (cerebral infarct)
• High pressure almost always causes multiple
  hemorrhages in the kidneys, producing many areas
  of renal destructions and, eventually, kidney
  failure, uremia and death

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• Blood pressure should be regularly checked
• Untreated HT can lead to fatal consequences
• To prevent or even treat HT, one must live a
  healthy lifestyle without stressful situations
• Two main types of HT Essential HT and Secondary
  HT

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References

• NCERx (2005) About Hypertension,
  www.about-hypertension.co.uk, Accessed 2 March
  2005
• NCERx (2005) Hypertension Symptoms and Normal
  Blood Pressure, www.detecting-hypertension.co.uk,
  Accessed 2 March 2005
• Guyton, A.C. Hall, J.E. (2000) Textbook of
  Medical Physiology 10th Edition, W.B. Saunders
  Company, pg. 199-206