Hypertension 1 Flashcards
When does a person have hypertension?
Bp- 140/90 (britain)
Bp- 130/80 - Optimal bp target 125/70 (american)
WHO- 140/90
What is the relationship between BP and risk of CVD?
There is a graded relationship between increasing BP and risk of CVD starting 115/75mmhg
What doubles the risk of CVD death?
An increase in BP of 20 mmHg systolic and 10 mmHg diastolic above ideal values doubles risk of CVD death regardless of age.
How common is hypertension?
Affects about 30-40% of the adult population
Prevalence >50% of persons over 60
Important risk factor for myocardial infarction, heart failure, stroke, cardiovascular disease and itaccounts for 41% of all cvd deaths
What causes blood pressure to fluctuates?
Physical stress and mental stress
What is stage 1 hypertension?
Clinic Bp 140/90 or higher
ABPM daytime average 135/85 mmHg or higher
What is stage 2 hypertension?
Clinic BP 160/100 or higher
ABPM daytime average 150/95 mmHg or higher
What is stage 3 or severe hypertension?
Clinic systolic BP 180/120 mmHg or higher
What is primary hypertension?
80-90% of cases and no cause has been identified
What is secondary hypertension?
10-20% of cases
Results in
- Chronic renal disease
- Renal artery stenosis
- Endocrine disease - cushings, conn’s syndrome (primary hyperaldosternism), phaeochromocyoma
Secondary hypertension is more common in younger patients
All hypertensive patients <40 should be referred to specialist for further investigations
What are hypertension associated risks?
(meaning what makes a patient more likely to have hypertension)
Risk from hypertension is associated with other risk factors
- Cigarette smoking
- Diabetes 5 - 30 x increase of MI
- Renal disease
- Male -2x risk
- Hyperlipidaemia
- Previous stroke/MI
- Left ventricule hyperterphohy 2x risk
What is the physiology of blood pressure?
BP is controlled by an integrated system
Primary contributers to BP are:
- Cardiac output: stroke volume x heart rate
- Peripheral vascular resistance
Each of these factors can be manipulated by drug therapy
What does sympathetic system activation produce?
Vasoconstriction - increases peripheral vascular resistance
Reflex tachycardia - Increases cardiac output
Increased stroke volume - Increases cardiac output
The actions of sympathetic system are rapid and account for second to second BP control.
When the sympathetic nervous system stimulates renin release what happens?
It produces angiotensin II and aldosterone
Angiotensin II - is a vasoconstrictor and stimulates the release of aldosterone from the adrenal glands
Aldosterone - Causes salt and water retention which increases the circulating blood volume.
What is RAAS?
Renin Angiotensin-Aldosterone system
It is pivotal in long term BP control
It is responsible for:
- Maintenance of sodium balance
- Control of blood volume
- Control of blood pressure
What is RAAS stimulated by?
Fall in Bp
Fall in circulating volume
Sodium depletion
- Any of these stimulate the release of renin from the juxtaglomerular apparatus
What does renin convert angiotensinogen to?
Angiotensin I
What is angiotensin I converted to?
Angiotensin II by angiotensin converting enzyme (ACE)
What are the polygenic aetilogy of hypertension?
- Major genes (single genes abnormalities)
- Poly genes (multiple genes involved)
- There are > 30 genes recognized as important but they individually account for at most 0.5 mmHg each
What are the polyfactorial aetilogy of hypertension?
- Environment
- Individual and shared
What are the likely causes of hypertension?
Increased reactivity of resistance vessels and resultant increase in peripheral resistance
- Hereditary defect of the smooth muscle lining of arterioles
A sodium homeostatic effect
- In hypertensive individuals, the kidneys are unable to excrete appropriate amounts of sodium for any given BP (pressure naturesis). As a result sodium and fluid retained and the BP increases.
What are other factors that cause hypertension?
- Age
- Genetics and family history
- Environment
- Weight
- Alcohol intake
- Race
How does age cause hypertension?
- Bp tends to rise with age - possibly as a result of decreased arterial compliance
- Hypertension in the elderly should be treated
How does genetics cause hypertension?
- A history of hypertension tends to run in families
- The closest correlation exists between siblings rather than parent and child
- It is possible that environmental factors common to members of the family also have a role in the development of hypertension
