Hypertension

Question 1

What is hypertension?

Answer 1

Level of blood pressure above which investigation and treatment do more good than harm

Question 2

What is the epidemiology of Htn?

Answer 2

Affects 1bn worldwide and is leading cause of global death, however normal-abnormal distinction is arbitrary

Question 3

What is the effect of ageing on Htn diagnosis?

Answer 3

Mean SBP and pulse pressure increase with age (as DBP stays constant) - almost all >80 would be hypertensive by current definition

Question 4

What is ambulatory BP?

Answer 4

Recorded automatically at regular intervals over 24hour period, often 5-10mmHg lower than recorded in clinic (white coat effect)

Question 5

What are the aetiologies of Htn?

Answer 5

Genetics: monogenic (rare), complex polygenic (common)

Environment: dietary salt (sodium), obesity, lack of exercise, alcohol, pre-natal environment, pregnancy (pre-eclampsia)

Question 6

What are the genetics of Htn?

Answer 6

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

Question 7

What is the major cause of primary Hypertension?

Answer 7

Idiopathic 85-95% of cases

Question 8

What is the threshold for Htn?

Answer 8

140/90 mmHg

Question 9

What are the causes of secondary Hypertension?

Answer 9

Renal disease

Tumours secreting aldosterone (e.g. Conn’s)

Tumours secreting catecholamines

Oral contraceptive pill

Pre-eclampsia

Rare genetic causes

Question 10

What percentage of cases of Htn are secondary?

Answer 10

5-15%

Question 11

What are the causes of primary Htn?

Answer 11

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

Question 12

What is the equation relating MAP and cardiac output?

Answer 12

MAP = CO x TPR

Question 13

What is Htn often associated with?

Answer 13

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

Question 14

What is isolated systolic hypertension?

Answer 14

Larger arteries become stiff for idiopathic reasons, rather than increased TPR, leading to SBP >140, DBP <90 mmHg and incidence increases with age

Question 15

What are the main consequences of Htn?

name 10

Answer 15

CHD, CVA, HF, AF, Dementia, Retinopathy, Vascular disease, Cardiomegaly, CHF, Aneurysms

Question 16

What are the effects of Htn on the heart?

Answer 16

Hypertension leads to increase in left ventricular wall mass leading to Cardiomegaly

Question 17

What are the effects of Htn on the eyes?

Answer 17

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

Question 18

What are the effects of Htn on the kidneys?

Answer 18

Renal dysfunction common, and extreme hypertension leads to rapidly progressive renal failure

Question 19

What is Microalbuminuria?

Answer 19

Hypertension increases albumin loss in the urine, due to a reduced glomerular filtration rate (also decreases with age, BP speeds up rate)

Question 20

What are the first treatments for Htn?

Answer 20

Weight loss, exercise, diet, alcohol reduction, smoking cessation.
All things I should do….

Question 21

What do ACE inhibitors do?

Answer 21

Reduce production of AGTII via RAAS

Question 22

What are Angiotensin receptor blockers?

Answer 22

Reduce AGTII binding to target organs - needed as can make AGTII without RAAS

Question 23

What are the aims of RAAS drugs on Tx?

Answer 23

Stop arteriolar vasoconstriction, ADH/aldosterone secretion and tubular sodium resorption, decreasing TPR and water retention

Question 24

What are Loop Diuretics?

Answer 24

Used in a crisis to block water reabsorption

Question 25

What are Thiazide diuretics?

Answer 25

Do not work through diuresis, but slowly reduce Peripheral vascular resistance

Question 26

What are Beta Blockers?

Answer 26

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

Question 27

What are calcium channel blockers?

Answer 27

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