Hypertension Flashcards
Describe the ranges for BP distinction?
normal SBP < 120, DBP < 80 prehypertension 120-139, 80-89 stage 1 140-159, 90-99 stage 2 160-179, 100-109 severe >180, >110
What is the benefit of ambulatory BP / home BP monitoring?
more reliable
5/10mmHg lower than measured at surgery
How do SBP, DBP and PP change with age?
SBP increase
DBP decrease
PP increase
What are the causes of hypertension?
IDENTIFIABLE CAUSES - SECONDARY
5% elderly, 15% younger
- renal disease (artery stenosis)
- Conn’s syndrome - tumour secrete aldosterone
- phaeochromosytoma - catecholamine secreting tumour
- oral contraceptive
- pre-eclampsia (pregnancy associated hypertension)
- rare genetic causes (Liddle syndrome)
UNINDENTIFIABLE CAUSE - PRIMARY/ESSENTIAL
(85-95%)
ENVIRONMENT dietary salt (Na) obesity/lack of exercise alcohol prenatal environment/birthweight pregnancy (pre-eclampsia) other exposures
GENETIC (responsible for 30-50% BP variation)
monogenic (rare)
- Liddle syndrome (mutation in amiloride sensitive tubular epithelial Na channel)
- mineral corticoid excess
complex polygenic (common) - interaction with sex/genes/environment
What is the pathophysiology of established hypertension?
increase TPR decrease arterial compliance normal CO/effective circulating volume central shift in volume decrease venous compliance
What causes increased TPR?
active narrowing of arteries (vasoconstriction) structural narrowing (growth, remodelling - adaptive) capillary loss (rarefaction - adaptive/damage)
What is isolated systolic hypertension?
over 60s more common SBP>140, DBP <90 due to increase stiffness of medium/large arteries (femoral and brachial) - pulse wave reflected - BP higher in larger arteries - no increase TPR (different mechanism)
What are the actual causes of primary hypertension?
endocrine/paracrine factors
increase SNS activity
kidney
- impaired renal function most common 2o cause
(renal artery stenosis or renal parenchymal disease)
- monogenic cause affect renal Na excretion
What general damage is caused by hypertension?
CHD, prevalence of congestive heart failure increases unlike other CVD because people live longer with bad hearts, hypertension precedes CHF 90% time and most of elderly cases
stroke (damage brain vessels)
peripheral vascular disease/atheromatous disease
heart failure (damage coronary vessels)
atrial fibrillation
dementia/cognitive impairment
retinopathy
How does heart and vasculature change with hypertension?
increase left ventricular wall mass (change in chamber size that increase risk of heart failure and death, arrhythmia)
increase intermediate thickness in hypertensive large arteries
arterial rupture/dilations (aneurysm) lead to thrombosis or haemorrhage (stroke - 85% due to clot)
What are hypertensive effects on the eye?
microvascular damage = RETINOPATHY
- papilloedema from swollen optic discs
- small artery walls thicken and arteriolar narrowing, vasospasm, impaired perfusion, increase leakage on back of retina = white patches
- high capillary pressure (damage and leakage)
- reduced capillary density (impaired PVR/perfusion)
blindness and blurred vision
What are the effects of hypertension on the kidney?
kidney dysfunction due to high vascular pressure affects filtration/reabsorption
- primary dysfunction = granular capsular surface, cortical thins, renal atrophy, dysfunction (microalbuminuria = higher albumin in urine)
- accelerated dysfunction= subcapsular haemorrhage (rare but can rapidly cause progressive renal failure)
- decrease GFR (speeds up natural age related decline)
Lifestyle treatment of hypertension?
weight loss
less alcohol
exercise
healthy diet
What is the goal of ARBs or ACEi?
ARBS
- block angiotensin II receptors
- body can make AngII via other mechanism
ACEi
- less angiotensin II produced
- decrease BP
What is the action of diuretics (thiazide)?
for hypertensive crisis with fluid overload
decrease PVR slowly long term not via diuresis
