Hypertension Flashcards
Definition of Stage 1 hypertension
Clinic BP = 140/90 or higher
ABPM / HBPM average = 135/85 mmHg
Definition of Stage 2 hypertension
Clinic BP of 160/100mmHg or higher
ABPM / HBPM average is 150/95 mmHg
Definition of Stage 3 hypertension
Clinic systolic BP = 180 mmHg
Clinic diastolic = 110 mmHg
Definitions of hypertension
High blood pressure happens if the walls of the larger arteries lose their natural elasticity and become rigid, and the smaller vessels constrict.
It can also result from an increase in the circulating blood volume.
Main effects of hypertension on the brain.
High BP is the most important risk factor for a stroke.
Very high pressure can cause a break in a weakened blood vessel which then bleeds to the brain - cerebral haemorrhage - stroke.
If a blood clot blocks a narrowed, atheromatous artery, it can result in cerebral infarction - causes stroke.
Main effects of hypertension on eyes.
Hypertensive retinopathy - high BP can eventually cause blood vessels in the eye leak or bleed. narrowing of retinal arterioles, increase risk of haemorrhage, hard exudates, and papilloedema.
Main effects of hypertension on the Heart.
MI - coronary arteries bringing oxygenated blood back to heart muscle become blocked = heart attack.
Congestive Heart Failure (CHF) - heart muscle initially compensates for increased work by pushing against the elevated pressure in the vessels - becomes hypertrophic - eventually unable to pump enough blood to supply the heart’s needs.
Main effects of hypertension on the kidneys.
Persistent high BP over time results in narrowing and thickening of renal arteries.
Kidneys can’t filter enough fluid - nitrogenous waste builds up in the blood.
Main effects of hypertension on the arterial tree.
Atherosclerosis - persistent BP accelerates the developing of hardening and narrowing of the arteries throughout the body.
Aortic aneurysm - the wall of the aorta (especially abdomen) may weaken and dilate with inherent risk of rupture.
Systems involved in BP determination.
Heart
- pumping i.e. CO
- CO = HR x SV
Blood vessels (tone)
- Total peripheral resistance
(sympathetic nervous system & abnormal sensitivity to catecholamines)
Vascular volume - capacitance of the vascular system
Arterial wall distensibility - baroreceptor control
Kidneys - regulate blood volume
Structural and functional changes to the arterial tree from prolonged hypertension.
Larger (elastic) arteries show internal lamina thickening, smooth muscle hypertrophy and fibrosis.
These changes reduce the lumen, increase the stress on the intima, increase turbulence, decrease endothelial function and reduce distensibility/compliance.
The smaller arteries show hyaline sclerosis which narrows the lumen.
The changes will increase Peripheral vascular resistance (PVR), which in turn increases BP.
Causes of increased peripheral vascular resistance.
Rapid development of atherosclerosis due to structural changes of the arterial tree because of prolonged hypertension.
Examples of these changes: internal lamina thickening, smooth muscle hypertrophy and fibrosis in the larger, elastic arteries. As well as hyaline sclerosis in the smaller arteries.
Decreased vascular compliance caused by this atherosclerosis results in disproportionately increased systolic BP in relation to diastolic BP.
Cerebral complications of hypertension
Transient cerebral Ischaemic Attack (TIA). Cerebral infarction. Itercerebral haemorrhage. Subarachnoid haemorrhage. Dementia.
Transient Ischaemic Attacks (TIAs)
caused by platelet emboli from atheromatous plaques, usually at the bifurcation of the common carotid arteries.
Cerebral infarction
caused by thrombosis or embolism of atheromatous artery
