12. Hypertension Flashcards
Blood pressure and age
Mean BP rises with age
Systolic rises
Diastolic does not rise
Pulse pressure rises
What is the difference between primary and secondary hypertension? Which one is more common?
Primary/ essential: unidentifiable cause (85-95% of cases)
Secondary Hypertension: identifiable cause (5-15%)
Name 6 common causes of secondary hypertension
Renal disease Tumours secreting aldosterone Tumours secreting catecholamines Oral contraceptive pill Pre-eclampsia/ pregnancy Genetic causes
Aetiology of primary hypertension
Genetics: Monogenic (rare) Complex polygenic (common) Environment: Dietary salt Obesity Alcohol Pre-natal environment Pregnancy
What monogenic disease causes hypertension?
Liddle’s syndrome
5 characteristics of hypertension
Increased TPR Decreased arterial compliance Normal cardiac output Normal blood volume/ ECV Central shift in volume
State 3 causes of elevated TPR in hypertension
Active narrowing of arteries
Structural narrowing of arteries
Capillary loss
What is the threshold for hypertension?
140/90 mm Hg
What organ has a major influence on hypertension?
Kidneys
hypertension is strongly associated with impaired renal flow and blood flow
What is isolated systolic hypertension due to?
Increasing stiffness of medium/large arteries
Candidate causes of primary hypertension
Kidney
Endocrine/ paracrine factors
Sympathetic nervous system
What do almost all monogenic causes of hypertension affect?
Renal Na+ excretion
What risks are increased by high BP?
Coronary heart disease Stroke Peripheral vascular disease/atheromatous disease Heart failure Atrial fibrillation Dementia /cognitive impairment Retinopathy
How is hypertension related to the heart?
Hypertension is associated with an increase in left ventricular wall mass (LVMI) and changes in chamber size
What is congestive heart failure?
The inability of the heart to adequately pump blood at normal filling pressures.
In how many cases does hypertension precede CHF?
90%
What can hypertension do to large arteries?
Arterial hypertrophy
Promote atherosclerosis
Aneurysms (which can lead to thrombosis and haemorrhage)
How does hypertension effect the eye?
Affects microvasculature Thickening of the wall of small arteries Arteriolar narrowing Vasospasm Impaired perfusion Increased leakage into surrounding tissue
What does hypertension do to the microvasculature?
Hypertension causes a decrease in capillary density and a subsequent elevation of capillary BP
How is the kidney effected in primary hypertension?
Renal dysfunction is common
e.g. increased (micro)albumin excretion in urine
How is the kidney effected in accelerated hypertension?
Extreme hypertension is now rare, but leads to rapidly progressive renal failure
How does hypertension effect to microalbuminia?
Causes increased albumin loss in the urine
Causes reduced glomerular filtration rate (GFR)
GFR declines with age even without high BP, which speeds up deterioration
What are the lifestyle modifications suggested as treatment for hypertension?
Weight loss
Exercise
Eat healthy
Less alcohol
What types of drug are used to treat hypertension?
ACE inhibitors
Angiotensin receptor blockers
When are loop diuretics used to treat hypertension?
in patients experiencing hypertensive crisis
How are thiazide diuretics used to treat hypertension?
Do NOT work through diuresis but because they slowly reduce PVR, mechanism still uncertain
How are Beta Blockers used to treat hypertension?
Blockage of β1 receptors in heart:
Reduced rate and force of contraction
Reduced cardiac output
Blockage of β1 receptors in kidney
Reduced secretion of renin
Reduced activity of RAAS
How are Calcium channel blockers used to treat hypertension?
Major mechanism: In vascular smooth muscle
Reducing Ca2+ influx reduces actin myosin cross bridge cycling
Minor mechanism: In the heart
Inhibition of Ca2+ influx reduces contractility (negative inotropy) and rate of conduction (negative dromotropy)
