Hypertension

Question 1

What are the two systems systemic blood pressure is regulated by?

Answer 1

Sympathetic nervous system
Renin-angiotensin-aldosterone system (RAAS)

Question 2

How does Renin impact the RAAS system?

Answer 2

It is released from the kidneys in response to low BP which decreases blood flow to the kidneys. Renin turns angiotensinogen into Angiotensin I.

Question 3

How does ACE (angiotensin-converting enzyme) affect the RAAS system?

Answer 3

Turns Angiotensin I into Angiotensin II.

Question 4

What does angiotensin II affect?

Answer 4

Angiotensin II is a constrictor of all blood vessels. It acts on smooth muscles. It also acts on the adrenal glands to stimulate the release of aldosterone.

Question 5

How does aldosterone affect BP?

Answer 5

Acts on the kidneys and stimulates reabsorption of sodium and water. This increases blood volume and thus increases BP

Question 6

What is the true definition of systemic hypertension?

Answer 6

Persistent elevation of systemic blood pressure. Systolic >160 mmHg.

Question 7

What are the common causes of systemic hypertension?

Answer 7

Secondary is the most common cause in cats and dogs. (>80% of cases). They involve conditions that increase CO or increase SVR.

Question 8

What are the two types of Blood pressure measurement methods?

Answer 8

Indirect- most practical; Doppler and oscillometric
Direct- gold standard but requires arterial catheterization.

Question 9

T/F If you use the wrong cuff size it can cause false BP readings.

Answer 9

True- cuff too big leads to falsely low BP
Cuff too small leads to falsely high BP

Question 10

T/F You should allow the patient to stand while taking BP in order to get an accurate stress-free reading.

Answer 10

False- need to gently restrain in ventral or lateral recumbency to limit the vertical distance from the heart base to the cuff.

Question 11

What are the possible areas of target organ damage (TOD)?

Answer 11

Eyes- can lead to blindness
Kidneys- Progression of Chronic kidney disease
Brain- Hemorrhagic stroke
Heart and vasculature- LV hypertrophy similar to HCM.

Question 12

What are the stages of hypertension?

Answer 12

Normotensive (minimal TOD risk): SBP <140 mmHg
Prehypertensive (Low TOD risk): 140-159 mmHg
Hypertensive (moderate TOD risk): 160-170 mmHg
Severely hypertensive (High TOD risk): >180mmHg

Question 13

What are the underlying causes of Hypertension in cats?

Answer 13

Chronic kidney disease and hyperthyroidism are the most common causes.
Adrenal disorders also can cause it- Hyperaldosteronism, Pheochromocytoma, hyperadrenocorticism.

Question 14

T/F Medications can also cause hypertension.

Answer 14

True- Corticosteroids, proin are some examples

Question 15

What are the underlying causes of hypertension in dogs?

Answer 15

Kidney disease- acute and chronic
Hyperadrenocorticism
Diabetes mellitus
Pheochromocytoma
Hyperaldosteronism (uncommon)

Question 16

When should hypertension be treated?

Answer 16

Severe hypertension- persistently >180
and/or
Evidence of TOD with moderate to severe hyptension
and/or
Persistent blood pressure >160 mmHg with disease associated with hypertension.

Question 17

What is considered the grey zone for hypertension treatment?

Answer 17

Moderately elevated blood pressure (160-180) with no evidence of TOD
Values >180 mmHg are less likely to be due to the “white coat effect”
Evaluate for TOD in these cases and recheck BP in 1-2 weeks.

Question 18

What are the 2 aspects of hypertension treatment?

Answer 18

1) address underlying disease if possible
2) Antihypertensive therapy- aimed at reducing CO,SVR, or both. Therapy with multiple pharmacologic agents may be needed (Dogs > cats)
+/- Dietary- weight loss and avoid high sodium

Question 19

How does Amlodipine affect hypertension? And what species is it used as first-line treatment?

Answer 19

Calcium channel blocker. First-line treatment in cats. Used in dogs with severe hypertension. Reduces BP by 30-50 mmHg.

Question 20

What does Amlodipine affect in humans that there are similar concerns about in dogs?

Answer 20

in people, it may activate RAAS –> increased proteinuria if BP is not significantly reduced.
Concurrent use of ACE inhibitors in people to block RAAS
Not proven in cats.

Question 21

What are the two types of ACE inhibitors?

Answer 21

Benazepril and enalapril- no evidence that one is better than the other

Question 22

How do ACE inhibitors affect BP?

Answer 22

ACE inhibiter will decrease the production of angiotensin II and cause systemic and glomerular effects. Preferentially vasodilates efferent arteriole of the glomerulus.

Question 23

How does vasodilating the efferent arteriole affect GFR?

Answer 23

it will reduce the pressure of the glomerulus which will decrease GFR and cause azotemia.
Angiotensin II causes vasoconstriction and increases GFR.

Question 24

After starting or increasing the dose of ACE inhibitors when do patients need to come back?

Answer 24

7-10 days after starting treatment to evaluate renal values and electrolytes.

Question 25

What electrolytes do ACE inhibitors affect?

Answer 25

Causes low sodium and high potassium look like addisons. Potassium over 6 will cause cardiac issues.

Question 26

T/F ACE inhibitors cause significant control of hypertension in cats.

Answer 26

False- it’s very minimal around 10 mm Hg.

Question 27

When are ACE inhibitors NOT first-line treatment in dogs?

Answer 27

When they have severe hypertension (>180-200 mmHg)
In this case, a calcium channel blocker (amlodipine) is often started in conjunction with an ACE inhibitor.

Question 28

How does Angiotensin II receptor blockers (Telmisartan) affect hypertension?

Answer 28

Inhibit RAAS by blocking the action of angiotensin II. Used for moderate hypertension in cats and can be used in dogs as well. Reduces proteinuria (decreases efferent constriction of glomerulus as well).

Question 29

What are the two emergency drugs? and why are they only used with severe life-threatening hypertension?

Answer 29

Hydralazine and Sodium Nitroprusside
They are direct vasodilators so they work VERY quickly. Have a greater risk for HYPOtension.

Question 30

What are the drugs usually used for Pheochromocytomas (tumors on adrenals- cause catecholamine production)

Answer 30

Phenoxybenzamine
Prazosin

Question 31

What kind of drug is Spironolactone?

Answer 31

Diuretic that acts as an aldosterone antagonist. Reduces sodium and water reabsorption. Useful with hyperaldosteronism

Question 32

What are the treatment goals of hypertension?

Answer 32

Avoid or correct TOD.
Gradual decrease in BP rather than acute marked decrease.
Goal to reach systolic BP between 110-140 mm Hg, minimal goal is <160mm Hg

Question 33

What are the signs of hypotension? What do you do if you see those signs?

Answer 33

Systolic BP <120 mmHg with clinical findings of weakness, syncope, or tachycardia.
Should decrease dose

Question 34

What are the monitoring steps after starting treatment?

Answer 34

if TOD is present, recheck BP in 3 days
If TOD is not present, recheck in 7-10 days
Once BP is stable, recheck every 3 months.