Aneurysms, Hypertension and Stroke Flashcards
What is hypertension?
sustained elevation of systolic and diastolic blood pressure > 140/90 mmHg
primary causes of hypertension
No identifiable cause
secondary causes of hypertension
- renal disease
- adrenal tumours
- aortic coarctation
- Rx/Antiangiogenic drugs
blood vessel damage by hypertension
contribute to all aspects of hypertensive organ damage. Blood vessels themselves undergo atheroma and aneurysm formation in large vessels, elastic reduplication in small vessels.
heart damage by hypertension
left ventricular hypertrophy, left heart failure (LHF)
lung damage by hypertension
pulmonary oedema due to LHF
kidney damage by hypertension
nephrosclerosis, renal failure
eye damage by hypertension
retinal capillary damage, haemorrhages, exudates
brain damage by hypertension
: microaneurysms and stroke, ischaemic cortical atrophy/ dementia.
what is hypertensive heart disease?
Increased load causes concentric left ventricular hypertrophy
what is hypertensive neuropathy?
- Granular cortical atrophy due to nephrosclerosis – loss of a glomerulus causes atrophy of the nephron.
- thickened renal arterioles
- glomerulosclerosis
early hypertensive retinopathy
‘Nicking, of retinal veins by overlying arterioles, normally they run alongside
moderate hypertensive retinopathy
- Straightened, wider capillaries
- Flame shaped haemorrhages
- ‘Cotton wool’ spots
(later) ‘Hard’ exudates around macula
late chronic/malignant hypertensive retinopathy
papilloedoma
haemorrhage
which blood vessels are involved in hypertension and which in atheroma?
Blood pressure is controlled by the arterioles, especially the latter – they are the ‘resistance vessels’ which can constrict or relax to alter the peripheral resistance.
atheroma
= bigger vessels
hypertension
= smaller vessels
how does blood vessel change in hypertension
- Resistance arterioles show elastic duplication
‘Hyaline arteriosclerosis’ damages arterioles as plasma exudes into the intima and deeper layers of the wall, sometimes out of the smaller vessels – glassy pink appearance on histology
The endothelium in hypertension is subject to damage by shearing forces applied by the high pressure cardiac output: atheroma is likely to develop at sites of endothelial damage due to hypertension
(Atheroma tends to affect larger blood vessels, so does not increase peripheral resistance sufficiently to cause hypertension. However the two diseases are encountered together most of the time
what is an aneurysm
bulge in the wall of a blood vessel
what is a true aneurysm?
when the entire wall of the vessel bulges. Sometimes part of the wall is cut or torn, usually by trauma, and the inner layers bulge through the tear – some people would term this a false aneurysm because not all layers are affected
what is a false aneurysm?
occur if the artery wall is punctured (eg during an arteriogram or angioplasty) and blood tracks out into adjacent tissue, but is contained locally by scar tissue. This expands as further blood is pumped out of the vessel wall.
why are aneurysms pulsatile?
Due to arterial blood flow, but this effect may be diminished by thrombus or severe atheromatous thickening
where do aneurysms occur?
arteries and occasionally the left ventricle but rare in veins
why do aneurysms occur at points of weakness?
due to atheroma or due to inflammatory damage (e.g. syphilis), occasionally due to connective tissue abnormalities and sometimes following trauma
what is a berry (saccular) aneurysm?
typically occur at the bifurcations of the arteries in the Circle of Willis.
Their rupture usually causes subarachnoid haemorrhage
what is a microaneurysms
typically occur in cerebral arteries in patients with hypertension.
Their rupture causes intracerebral haemorrhage