Hypertension Flashcards
Systemic blood pressure is a product of which of the following?
A. cardiac output and heart rate
B. cardiac output and systemic vascular resistance
C. systemic vascular resistance and stroke volume
D. stroke volume and cardiac output
B. cardiac output and systemic vascular resistance
Systemic blood pressure is regulated by what 2 systems?
- sympathetic nervous system (ex. stress –> increased release of catecholamines –> vasoconstriction –> inc BP)
- Renin-angiotensin-aldosterone system
Where is renin produced and what is its function?
Renin is produced by the kidneys in response to low blood pressure.
It functions to convert angiotensinogen into angiotensin I
What is produced by the liver than gets converted by renin into angiotensin II?
Angiotensinogen
What organ produced angiotensin-converting enzyme (the enzyme needed to convert angiotensin I to angiotensin II)?
The lungs
What are the 2 main results of angiotensin II?
- acts on the adrenal gland to stimulate the release of ALDOSTERONE
- Acts on smooth muscle of the blood vessels and causes VASOCONSTRICTION
When angiotensin II acts on the adrenal glands to produce aldosterone, what effect does aldosterone then have on the kidneys and blood pressure?
Aldosterone stimulates reabsorption of sodium and water (which is increases blood volume and thus blood pressure).
What BP value defines systemic hypertension?
A persistent elevation of BP:
systolic > 160 mmHg
diastolic > 120 mmHg
T/F: the most common cause of systemic hypertension in companion animals is idiopathic.
false – it is most commonly secondary and is causes by conditions that increase cardiac output or increase systemic vascular resistance.
What physical exam finding in cats is highly supportive of systemic hypertension?
retinal hemorrhage and retinal vessel tortuosity
What blood pressure measurement method is described below?
Preferred method for SMALL cats and dogs. Measures only systolic
Indirect – Doppler
What blood pressure measurement method is described below?
Preferred method for medium to large dogs. Measures systolic, diastolic, and mean.
Indirect – Oscillometric
What is considered the gold standard method to measure blood pressure?
direct – arterial catheterization
it is the most accurate, but it is not always feasible.
Blood pressure cuff width should be _____% (range) the circumference of the chosen site.
Why?
30-40
too big –> false low BP
too small –> false high BP
what 2 areas can you use for blood pressure measurement with doppler or cuffs?
limbs
tail
note: restrain in ventral or lateral recumbency to limit vertical distance from the heart base to the cuff
T/F: anxiety induced situational hypertension will be fairly obvious to distinguish from true hypertension because values will not be markedly elevated.
false – anxiety induced situational hypertension can be very marked.
When measuring blood pressure, describe the technique to ensure you are getting the MOST accurate results.
Always discard your 1st measurement
Average the values of 5-7 measurements
Always note pt demeanor, cuff size, and measurement site to be consistent during follow-up measurements.
What are the 4 possible areas of target organ damage?
- eyes
- kidneys
- brain
- heart and vasculature
The risk for target organ damage becomes moderate to high when systemic blood pressures rise above what value?
> 160-180
<159 have low-minimal risk
Primary hypertension is less common in cats than secondary. What are the 4 MOST common causes of secondary hypertension in CATS?
- chronic kidney disease*
- hyperthyroidism*
- adrenal disorders (conn’s, pheochromocytoma, cushing’s)
- medications (steroids, proin, erythropoietin)
Primary hypertension is more uncommon in dogs than secondary. What are the 5 MOST common secondary causes of hypertension in DOGS?
- Kidney disease*
- hyperadrenocorticism*
- Diabetes mellitus
- Pheochromocytoma
- Hyperaldosteronism
Which of the following factors is NOT a known factor to commonly affect blood pressure?
A. age
B. breed
C. blood type
D. obesity
E. anxiety/stress
F. drugs
C. blood type
When should hypertension be treated?
(3 criteria)
- severe hypertension (>180)
- evidence of TOD with mod-sev hypertension
- persistent BP>160 with disease associated with hypertension (CKD, cushings, etc.)
When patients fall into the “gray zone” of needing treatment for hypertension (moderately elevated BP (160-180) with no TOD), what should your plan be?
Evaluate patient for TOD and recheck BP in 1-2 weeks.
When is hypertensive treatment NOT recommended?
Patients with PREhypertension (140-159) with NO clinical signs
In these patients, its best to monitor BP during future visits.
The aim/goals of treatment for hypertension are?
- address the underlying disease
- reduce CO, SVR, or both
- weight loss in obese patients
- avoid high-sodium treats and diets.
Which drug is FIRST line treatment for hypertension in CATS?
*give MOA too *
Amlodipine
MOA = Ca channel blocker –> vasodilation –> decrease BP
Note: it can also be used in dogs with severe hypertension
Amlodipine reduces blood pressure by _____ mmHg.
30-50
It does take 7-10 days to take full effect.
Note: this is why a lower dose is used first to see the effects, then BP is rechecked in 7-10d to see is dose adjustments are needed
Why is amlodipine commonly combined with an ACE-inhibitor in dogs?
amlodipine may activate RAAS leading to increased proteinuria if the blood pressure is not significantly reduced.
ACE-inhibitors reduce proteinuria.
What is the mechanism of action of ACE-inhibitors (benazipril and enalapril)?
ACE-inhibitors inhibit the angiotension converting enzyme (ACE), which leads to decreased production of angiotensin II.
This results in vasodilation and decreased aldosterone production. Additionally, ACE inhibitors preferentially vasodilates the efferent arteriole of the glomerulus, which reduces proteinuria.
The downside to this is it may cause azotemia.
After you start a patient on an ACE-inhibitor, what should follow-up look like?
First, ensure that they are well-hydrated before starting.
You should evaluate their renal values and electrolytes 7-10 days after starting treatment or after increasing the dose.
T/F: ACE-inhibitors have minimal control of hypertension in cats, reducing BP by only ~10 mmHg.
true
they are the first line treatment in dogs, except dogs with SEVERE hypertension (>180)
What is the MOA of angiotensin II receptor blockers such as telmisartan?
They inhibit RAAS by blocking the action of angiotensin II.
They serve as an alternative to ACE-inhibitors because they also reduce proteinuria.
What is the use for telmisartan?
moderate hypertension in cats (<200)
and dogs too.
What are 2 “emergency” drugs that are rarely needed but used for severe life-threatening hypertension?
- hydralazine
- sodium nitroprusside
they carry a risk for causing hypotension
What 2 drugs are used in cases of hypertension caused by pheochromocytomas?
- phenoxybenzamine
- prazosin
What is the MOA of spironolactone in the treatment of hypertension?
spironolactone is a diuretic that acts as an aldosterone antagonist which reduces sodium and water reabsorption, thus decreasing BP.
This drug is useful in cases of hyperaldosteronism.
T/F: when patients have hypertension, we want to start treatment as soon as possible in order to reduce their systemic blood pressure acutely to avoid TOD.
false – yes, its important that the blood pressure is decreased in a timely fashion to avoid TOD, but a gradual decrease in BP rather than acute is the goal.
The goal is to reach 110-140 mmHg. Any BP <120 with signs of weakness, syncope, or tachycardia is indicative of hypotension and the dose needs to be decreased.
