Lecture 11- Controlling Blood Pressure In Patient With Hypertension

Question 1

What is hypertension?

Answer 1

Sustained increase in blood pressure

Question 2

What is the normal range for blood pressure in an adult?

Answer 2

90/60mmHg to 120/80 mmHg but normal can vary

Stage 1= over 140/90

Stage 2= over 160/100

Severe= over 180 systolic or 110 diastolic

Question 3

Primary vs secondary hypertension?

Answer 3

With primary the cause is unknown in 95% of cases

Secondary cause can be defined eg chronic renal disease, Cushing syndrome etc

Treat cause in secondary

Question 4

Some diseases attributable to hypertension?

Answer 4

MI
Coronary heart disease
Aortic aneurysm 
Retinopathy 
Peripheral vascular disease 
Heart failure

Question 5

How do you know if you have hypertension?

Answer 5

It is asymptomatic

Question 6

How does high blood pressure lead to damage?

Answer 6

Increased afterload- LV hypertrophy and heart failure. O2 demand increased leading to MI and ischaemia

Arterial damage- atherosclerosis and weakened vessels leading to aneurysm, MI, retinopathy etc

Question 7

How do you check for organ damage with hypertension?

Answer 7

Look at functioning of kidneys, brain, arteries, heart and eyes

Question 8

What is blood pressure?

Answer 8

Flow X resistance

Question 9

Calculating mean arterial BP?

Calculating cardiac output?

Answer 9

CO X TPR

CO= SV X HR

Question 10

How is blood pressure regulated in the short term?

Answer 10

Baroreceptors reflex involving sympathetic and parasympathetic inputs to heart and vasculature

Question 11

How is blood pressure regulated in the medium to long term?

Answer 11

Through neurohumoral responses and sodium balance and so extracellular fluid volume

Controlling sodium levels controls extracellular fluid volume

Question 12

What are the four parallel neurohumoral pathways that control circulating volume and BP?

Answer 12

Renin angiotensin-aldosterone system

Sympathetic nervous system

ADH

ANP (lowers, others raise)

Question 13

Renin angiotensin aldosterone system (RAAS)?

Answer 13

Can be targeted by ACE inhibitors which reduces sodium reabsorption and prevents the breakdown of bradykinin which acts as a vasodilator.

Question 14

What stimulates renin release from the juxtaglomerular apparatus?

Answer 14

Reduced NaCl delivery to distal tubule

Reduced perfusion pressure in kidney

Sympathetic stimulation to JGA

Question 15

How does the RAAS work?

Answer 15

Angiotensinogen converted to angiotensin I by renin. Angiotensin I is converted to angiotensin II by ACE (angiotensin converting enzyme).
Angiotensin II then causes vasoconstriction sodium reabsorption and stimulates aldosterone which also helps retain sodium

Question 16

What angiotensin II receptors are there?

Answer 16

AT1 and AT2.

AT1 has main actions.
Arterioles=vasoconstriction
Kidney= sodium reabsorption 
Sympathetic= adrenaline secretion
Adrenal cortex=aldosterone release 
Hypothalamus=thirst and ADH secretion

Question 17

How does ACE (angiotensin converting enzyme) interact with bradykinin?

Answer 17

Converts angiotensin I to angiotensin II and causes bradykinin to be broken down into fragments

Question 18

Role of bradykinin in blood pressure?

Answer 18

Acts as a vasodilator

Question 19

Why are ACE inhibitors effective drugs and give an example of one?

Answer 19

They prevent angiotensin I being converted to angiotensin II and they also prevent bradykinin from being broken down which prevents those compounds from exerting their BP elevating actions.

EG Ramipril and lisinopril

Question 20

Sympathetic nervous system control of BP?

Answer 20

Vasoconstriction and reduced renal blood flow and glomerular filtration.
Increased sodium reabsorbance and stimulation of renin release from juxtaglomerular cells.

Question 21

ADH and blood pressure?

Answer 21

Increased water reabsorption
Stimulated by increased plasma osmolarity or severe hypovolaemia
Stimulates sodium reabsorption and causes vasoconstriction

Question 22

Natriuretic peptides and BP control?

Answer 22

Produced and stored by atrial myocytes. Release in response to stretch of low pressure sensors. Cause sodium excretion to reduce circulating volume. Opposite effects to others (vasodilation etc)

Question 23

Role of prostaglandins?

Answer 23

Oppose effects of RAAS and sympathetic nervous system.

Reduce sodium reabsorption and cause vasodilation etc

Question 24

Dopamine?

Answer 24

Formed in kidney from L-Dopa. Causes vasodilation, reduces NaCl absorption etc

Question 25

Secondary hypertension: renovascular disease?

Answer 25

Occlusion of renal artery decreases perfusion pressure. Juxtaglomerular apparatus tricked into thinking BP is low and so renin produced etc

Question 26

Renal parenchymal disease?

Answer 26

Early stage lose vasodilator, later stage retain sodium and water due to inadequate glomerular filtration

Question 27

Give examples of adrenal causes of secondary hypertension?

Answer 27

Cushing syndrome and a tumour of the adrenal medulla

Question 28

First approaches to treatment of hypertension?

Answer 28

Diet
Exercise
Reduce sodium intake
Reduce alcohol

Question 29

Pharmacological treatments for high BP?

Answer 29

Ace inhibitors

L-type channel blockers like verapamil to relax smooth muscle

Alpha 1 receptor blockers like doxazosin to relax smooth muscle

Thiazides diuretics to reduce circulating volume

Beta blockers usually only used if other indication like MI

Question 30

What pharmacological BP treatments for what age groups?

Answer 30

Younger= ACE inhibitors

Over 55= vasodilator and diuretics

Most people require multiple drugs to bring about desired effect