153 - Hypertension Flashcards
Proportion of Australians over 18 who are hypertensive
~30%
Arbitrary definition of hypertension
Systolic over 140mmHg and diastolic over 90mmHg
Primary/essential hypertension
No specific identifiable cause.
Responsible for 90-95% of hypertension
Secondary hypertension
Identifiable pathology that is causing hypertension
5-10% of hypertension
Benign hypertension
Blood pressure rises gradually, over a long period.
Majority of cases.
Malignant hypertension
Blood pressure rises rapidly, over a short period.
Minority of cases.
Two forces that leads to blood pressure
Cardiac output (stroke volume, heart rate, blood volume) and resistance in arteiroles.
Aortic changes from age
1
2
3
Aorta: loss of elasticity, hardening i.e. ‘arteriosclerosis’
Media: fragmentation of elastin, increased collagen
Intima: increased collagen
What effect does hypertension have on blood vessels?
Exacerbates age-related changes.
Aorta: loss of elasticity, hardening i.e. ‘arteriosclerosis’
Media: fragmentation of elastin, increased collagen
Intima: increased collagen
Age-related arterial changes in small and medium arteries
1
2
– Media: fragmentation of elastin, increased collagen, sometimes calcification
– Intima: increased collagen -> thickening
Age-related arteriolar changes 1 2 3 4
Arteriolar hyalinosis/hyaline arteriolosclerosis
– Deposition of plasma proteins in wall
– Increased collagen
– Smooth muscle atrophy
–Arteriole wall becomes thickened by homogenous eosinophilic glassy material (‘hyaline’) and the lumen narrowed
Arteriolar change in hypertension, or with age
Arteriolar hyalinosis/hyaline arteriosclerosis
What can hyaline arteirolosclerosis lead to?
Can slightly increase diastolic blood pressure with age.
Genetic predispositions to primary hypertension 1 2 3 4 5 6
– Polygenic genetic influences. Genetic polymorphisms may influence for example
• Sympathetic responses
• Transport of ions across cell membranes in vessels or kidney
• Arteriolar responses to local regulatory factors
• Activity of components of the renin-angiotensin-aldosterone system and secretion of renin
• Genetic determinants may also influence target organ damage
Lifestyle factors contributing to primary hypertension 1 2 3 4
- Amount of salt in diet
- Alcohol intake
- Levels of physical activity
- Abdominal obesity and metabolic syndrome (can influence e.g. renal sodium retention, increased sympathetic activity, ion transport across cell membranes)
Age, gener, race predispositions to primary hypertension
1
2
- Prevalence lower in premenopausal females than in age-matched males and in postmenopausal women
- Higher in those of African descent
Broad divisions of primary hypertension
High plasma renin and low plasma renin.
Possibly correlate with vasoconstrictor and volume-dependent forms of hypertension.
Systolic hypertension with wide pulse pressure
1
2
Several groups:
• Decreased compliance of aorta (arteriosclerosis).
Age related changes –> loss of elasticity -> elevation of the systolic pressure and widening of the pulse pressure. If excessive -> isolated systolic hypertension
• Increased stroke volume e.g. aortic regurgitation, hyperthyroidism, fever (can treat some of these causes)
Most common pathology leading to secondary hypertension
Renal disease
EG: diabetic glomerulosclerosis, certain glomerulonephritides, polycystic renal disease, chronic renal diseas
Examples of non-renal causes of secondary hypertension 1 2 3 4
– Endocrine e.g. adrenocortical adenoma producing cortisol or aldosterone, phaeochromocytoma, pituitary adenoma producing ACTH
– Vascular e.g. coarctation of aorta, renal artery stenosis
– Medications e.g. corticosteroids, oestrogen
– Other e.g. neurogenic/cerebral, hypercalcemia, toxaemia of pregnancy, obstructive sleep apnoea, cocaine use
Coarctation of the aorta
Congenital narrowing of aorta
Does atherosclerosis cause hypertension
Under certain circumstances.
EG when it is stenosing renal arteries.
Effects of essential hypertension
Causes complications by causing concentric left ventricular hypertrophy and by predisposing to pathology in arteries and arterioles.
Examples of arterial and arteriolar effects of hypertension
1
2
3
• Large and medium sized arteries
- Atherosclerosis
- Aortic dissection
•Medium arteries: berry aneurysm (Circle of Willis)
•Arterioles: hyaline arteriolosclerosis/arteriolar hyalinosis
