Hypertension

Question 1

What is normal systemic arteriole SYSTOLIC pressure?

Answer 1

120mmHg

Question 2

What is normal systemic arteriole DIASTOLIC pressure?

Answer 2

80mmHg

Question 3

What is the difference in pressure between LA and LV

Answer 3

Systolic
LA = 10
LV = 120

Diastolic
LA = 0-5
LV = 10

Question 4

What is systemic hypertension?

Answer 4

Persistently elevated systemic blood pressure
Systolic >160mmHg
Diastolic >100mmHg

Question 5

Why might an animal have an increased blood pressure?

Answer 5

Fear/excitement
Old age
Drugs
* Fluid therapy
* Steroids
* Cyclosporin A
* Phenylpropanolamine
Underlying disease
* Renal disease
* Hyperadrenocorticism (DOG)
* Hyperthyroidism (CAT)
* Diabetes mellitus
* Hyperaldosteronism
* Phaechromocytoma
Obesity
Breed - sighthounds have increase of 10-20mmHg

Question 6

How does HAC lead to systemic hypertension?

Answer 6

Increases renal retention of salt and water
Overproduction of renin = vasoconstriction

Question 7

How does hyperthyroidism lead to systemic hypertension?

Answer 7

Increases sensitivity of myocardium to catecholamines

Question 8

How does diabetes lead to systemic hypertension?

Answer 8

Volume expansion due to hyperglycaemia
Overproduction of renin = vasoconstriction

Question 9

Phaechromocytoma

Answer 9

Tumour in adrenal gland

Question 10

Hyperaldosteronism

Answer 10

Adrenals release to much aldosterone
Secretes potassium in to DCT
Aldosterone causes sodium potassium pump to work harder
Results in retention of Na and water

Question 11

What influences blood pressure?

Answer 11

Cardiac output and peripheral vascular resistance

BP = CO X PVR

Question 12

What factors influence CO?

Answer 12

Stroke volume and heart rate

CO = SV X HR

Question 13

What factors influence stroke volume?

Answer 13

Stroke volume = EDV = ESV

Preload (EDV)
Afterload
Contractility (ESV)

Question 14

Preload

Answer 14

Volume of blood in ventricles at the end of diastole
EDV

Question 15

Afterload

Answer 15

Resistance to ventricular ejection
The pressure in arterial vasculature

Question 16

Contractility

Answer 16

Force by which ventricle contracts
Determines volume of blood in ventricle at the end of systole
ESV

Question 17

Initiating causes of systemic arterial hypertension

Answer 17

Chronic fluid accumulation
* Increases preload (EDV)
Persistently high HR
Chronic vasoconstriction

Question 18

Perpetuating causes of systemic arterial hypertension

Answer 18

Extravasation of plasma into vessel wall
Vascular smooth muscle hypertrophy
Renal disease

Question 19

How does renal disease perpetuate arterial systemic hypertension?

Answer 19

When arterial pressure increases, the nephron reduces sodium and water reabsorption thus increasing sodium and water excretion to compensate
* High GFR

Results in RAAS activation

Question 20

Which organs are effected by arterial systemic hypertension?

Answer 20

Clinical signs only present with end organ damage
Eyes
CNS
Kidneys
Heart

Question 21

Ocular signs of arterial systemic hypertension

Answer 21

Acute blindness
Retinal detachment
(Blood vessels can burst in eye)

Question 22

CNS signs of arterial systemic hypertension

Answer 22

Disorientation
Ataxia
Stupor
Seizures

Question 23

Renal signs of arterial systemic hypertension

Answer 23

PUPD
Proteinuria

Question 24

Cardiac signs of arterial systemic hypertension

Answer 24

Left ventricular hypertrophy
Murmurs
Arrhythmias
CHF

Question 25

Methods of measuring arterial systemic blood pressure

Answer 25

Direct methods * Invasive - arterial catheter Indirect methods * Non-invasive - compression cuff * Doppler * Oscillometric Avoid using sedation

Question 26

Doppler BP measurement

Answer 26

Manual Requires more training More user variability Only provided systolic BP

Question 27

Oscillometric BP measurement

Answer 27

Automatic Time consuming Provides systolic, diastolic and mean

Question 28

Where should you place a cuff on a cat vs dog

Answer 28

Cat - forelimb Dog - Tail

Question 29

What are catecholamines?

Answer 29

Catecholamines are neurotransmitters produced by adrenals (Epinephrine, dopamine, norepinephrine etc) Act on sympathetic nervous system Adrenergic receptors

Question 30

How do levels of catecholamines affect BP?

Answer 30

Cause increase in HR/CO and systemic vascular resistance by causing vasoconstriction A1 Constricts heart A2 Constricts lungs B1 Dilates heart/vasculature B2 Dilates lungs

Question 31

When to treat arterial systemic hypertension

Answer 31

When there has been end organ damage When there is underlying disease identified High risk to EOD when >180mmHg