Hypertension Flashcards
What is hypertension?
Level of blood pressure above which investigation and treatment do more good than harm
What is the epidemiology of Htn?
Affects 1bn worldwide and is leading cause of global death, however normal-abnormal distinction is arbitrary
What is the effect of ageing on Htn diagnosis?
Mean SBP and pulse pressure increase with age (as DBP stays constant) - almost all >80 would be hypertensive by current definition
What is ambulatory BP?
Recorded automatically at regular intervals over 24hour period, often 5-10mmHg lower than recorded in clinic (white coat effect)
What are the aetiologies of Htn?
Genetics: monogenic (rare), complex polygenic (common)
Environment: dietary salt (sodium), obesity, lack of exercise, alcohol, pre-natal environment, pregnancy (pre-eclampsia)
What are the genetics of Htn?
30-50% variation in BP attributable to genetic variation
Monogenic disease = <1% hypertension e.g. Liddle’s syndrome and apparent mineralocorticoid excess
Complex polygenic causes are much more significant; multiple genes with small effect
What is the major cause of primary Hypertension?
Idiopathic 85-95% of cases
What is the threshold for Htn?
140/90 mmHg
What are the causes of secondary Hypertension?
Renal disease
Tumours secreting aldosterone (e.g. Conn’s)
Tumours secreting catecholamines
Oral contraceptive pill
Pre-eclampsia
Rare genetic causes
What percentage of cases of Htn are secondary?
5-15%
What are the causes of primary Htn?
Kidneys: have a key role in BP regulation based on salt intake (if low salt diet then BP does not increase with age - monogenic causes usually related to genes affecting renal Na+ excretion)
Endocrine
Sympathetic Nervous System: high SNS activity linked to hypertension
What is the equation relating MAP and cardiac output?
MAP = CO x TPR
What is Htn often associated with?
Increased TPR (active narrowing of arteries, structural narrowing and capillary loss)
Decreased arterial compliance
Normal CO
Normal blood volume
Central shift in volume 2/2 reduced venous compliance
What is isolated systolic hypertension?
Larger arteries become stiff for idiopathic reasons, rather than increased TPR, leading to SBP >140, DBP <90 mmHg and incidence increases with age
What are the main consequences of Htn?
name 10
CHD, CVA, HF, AF, Dementia, Retinopathy, Vascular disease, Cardiomegaly, CHF, Aneurysms
What are the effects of Htn on the heart?
Hypertension leads to increase in left ventricular wall mass leading to Cardiomegaly
What are the effects of Htn on the eyes?
Microvascular damage to the retina in hypertension, leading to swelling of the optic disc, vasospasm, impaired perfusion, narrowed arteries and increased leakage to surrounding tissue
What are the effects of Htn on the kidneys?
Renal dysfunction common, and extreme hypertension leads to rapidly progressive renal failure
What is Microalbuminuria?
Hypertension increases albumin loss in the urine, due to a reduced glomerular filtration rate (also decreases with age, BP speeds up rate)
What are the first treatments for Htn?
Weight loss, exercise, diet, alcohol reduction, smoking cessation.
All things I should do….
What do ACE inhibitors do?
Reduce production of AGTII via RAAS
What are Angiotensin receptor blockers?
Reduce AGTII binding to target organs - needed as can make AGTII without RAAS
What are the aims of RAAS drugs on Tx?
Stop arteriolar vasoconstriction, ADH/aldosterone secretion and tubular sodium resorption, decreasing TPR and water retention
What are Loop Diuretics?
Used in a crisis to block water reabsorption
What are Thiazide diuretics?
Do not work through diuresis, but slowly reduce Peripheral vascular resistance
What are Beta Blockers?
beta1 (endogenous catecholamine receptors) receptors blocked in heart to reduce rate and force of contraction to reduce output and in the kidneys to stop renin secretion/RAAS activity
What are calcium channel blockers?
Major effect in vascular smooth muscle to reduce Ca2+ influx to reduce cross bridge cycling, and have a minor effect to reduce contractility and rate of conduction in the heart
