Lecture 5 - Hypertension Flashcards
What are the major determinants for blood pressure?
cardiac output and peripheral resistance
What are the regulation systems for blood pressure?
baroreceptor reflex
renin-angiotensin system
aldosterone
What minute-minute regulates blood pressure?
baroreceptors
What long term regulates blood pressure?
RAAS
How does RAAS regulate blood pressure?
hypovolemia –> renin from kidney goes to liver and activates angiotensinogen into angiotensin 1 –> ACE converting enzyme from lungs converts angiotensin 1 to angiotensin 2 –> potent vasoconstrictor and potent aldosterone stimulator –> improve blood volume and pressure
Constriction of efferent arteriole (increases/decreases) glomerular capillary pressure.
increases
Angiotensin 2 vasoconstricts….
efferent arteriole
What do ACE inhibitors do?
block ACE converting enzyme from converting angiotensin 1 to angiotension 2
What do ARBs do?
blocks angiotensin 2 from stimulating aldosterone or vasocontricting
Examples of ACE inhibitors
enalapril
benazepril
Examples of ARBs
telmisartan
Aldosterone is a?
mineralocorticoid
Where is aldosterone produced?
zona glomerulosa
What is the stimuli for release?
angiotension 2
hyperkalemia
Aldosterone effects on kidneys
potassium excretion and sodium retention
Hyperaldosteronism does what to Na and K?
high Na
low K
Addison’s, with a mineralocorticoid deficiency, does what to K and Na?
high K
low Na
How do you choose appropriate cuff size?
choose cuff width of 30-40% leg circumference
If your BP cuff is too narrow, what will you see?
overestimation of
4 reasons for chronic activation of RAAS
- endothelial dysfunction
- tissue fibrosis
- cellular remodeling
- proteinuria
How many measurements should you take for BP?
5-7
Gold standard for direct BP measurement?
arterial cath
Most common causes of secondary hypertension
D - diabetes mellitus
P - pheochromoctyoma
A - hyperAldosteronism
C - cushing’s
T - hyperThyroidism
What are the indirect, non-invasive measurement techniques for BP?
doppler
oscillometric
Doppler reads what arterial BP?
systolic
Doppler reads what BP in cats?
mean
What is the most accurate BP reading?
mean arterial BP
Types of Hypertension
white coat hypertension
secondary hypertension
idiopathic/primary hypertension
Describe white coat hypertension.
consequence of anxiety or stress!!!
Tx for White Coat Hypertension
none
Most common type of hypertension
secondary
Describe secondary hypertension
persistent, pathologic increase in BP concurrent with disease, drugs, toxins
Describe idiopathic or primary hypertension
persistent in the absence of an underlying identifiable cause
usually multifactorial: genetics, lifestyle, environment
Which type of hypertension is difficult to prove in dogs and cats because of subclinical renal disease?
idiopathic or primary hypertension
Target organ damage from hypertension?
B - brain (encephalopathy)
A - arteries
R - retina (detachment)
K - kidney (proteinuria)
H - heart (failure)
When should you measure BP?
If there are clinical abnormalities consistent with target organ damage, if there is a disease present that’s associated with secondary hypertension
annual screening
How would you classify a BP of <140mmHg and what’s the risk of end organ damage?
normotensive
How would you classify a BP of 141-159mmHg and what’s the risk of end organ damage? When should you recheck?
pre-hypertensive; low risk; monitor and recheck in 6mo
How would you classify a BP of 160-179mmHg and what’s the risk of end organ damage? When should you recheck?
hypertensive, moderate risk; recheck in 4-8wks
How would you classify a BP of >180mmHg and what’s the risk of end organ damage? When should you recheck?
severely hypertensive, high risk, recheck in 1-2wks
What is considered hypotensive?
<90mmHg
Tx of Hypertension
reduce BP over weeks
RAAS inhibitors
ARBs
What’s the frontline for mild to moderate hypertension in dogs?
ACE inhibitors, only reduces 10-15mmHg
Side effects of ACE inhibitors
GI, hyponatremia, hyperkalemia, worsening azotemia
What is the frontline for severe hypertension in cats?
CCB BID
Side effects of calcium channel blockers
hypotension
gingival hyperplasia
peripheral edema
Tx for Severe Hypertension in dogs
ACE inhibitor or ARB
+ CCB
Mild Hypertension Tx in cats
CCB SID
If a cat has hypertension and proteinuria, what should you add into tx plan?
ARB
