Hypertension Flashcards
What 2 things affect systemic BP?
- cardiac output - HR (SNS, cardiac function), stroke volume (blood volume, RAAS)
- systemic vascular resistance - vascular tone (SNS, RAAS)
What is systemic hypertension? What are the 2 types?
persistent elevation in systemic BP with systolic > 160 mmHg
- primary/essential = idiopathic
- secondary = most common in dogs and cats
What are the 4 most common causes of hypertension in dogs?
- acute/chronic kidney disease
- hyperadrenocorticism
- diabetes mellitus - more modest increase
- pheochromocytoma - increased catecholamine release from adrenal medulla (severe)
What are the 4 most common causes of hypertension in cats?
- CKD**
- hyperthyroidism*
- primary hyperaldosteronism (no response to potassium or anti-hypertensives)
- hyperadrenocorticism
What are 5 other factors that affect BP?
- age
- breed - Sighthounds
- obesity - < 5 mmHg in dogs
- anxiety/stress*
- pharmacologic agents - alpha-agonists = vasoconstriction
What are the 4 target organs affected by hypertension?
- eye
- brain
- kidney
- heart
eye, brain, and kidney have vascular autoregulation to offset changes in BP
What are some ocular signs of systemic hypertension?
- hemorrhage of the retina, vitreous, or anterior chamber
- retinal vessel tortuosity
- retinal edema and detachment (bullous, generalized)
- optic nerve edema and atrophy
What are some neurologic signs of systemic hypertension?
- vestibular signs —> head tilt, nystagmus
- focal neurological deficits
- behavior abnormalities
- seizures
What are some renal signs of systemic hypertension?
- decreased renal function
- proteinuria
- glomerular and tubulointerstitial changes
What are some cardiac signs of systemic hypertension?
- left ventricular hypertrophy
- gallop rhythm
- heart mumur
- epistaxis (changes in vessels)
Why is it important to measure BP?
evidence of target organ damage
In what 5 situations should BP be measured in cats?
- kidney disease, proteinuria
- endocrinopathies (hyperthyroidism, euthyroidism)
- auscultable cardiac abnormalities
- cardiomegaly, cardiac wall hypertrophy
- older age
In what 3 situations should BP be measured in dogs?
- kidney disease, proteinuria
- endocrinopathies - HAC, DM
- cardiac hypertrophy
What is the gold standard for measuring BP?
direct —> anesthetized patient with arterial catheters
What are the 2 most common indirect ways to measure BP?
- Doppler
- oscillometric
(+ photoplethysmography, auscultatory)
What does oscillometric BP measure? What 3 arteries are used?
systolic, diastolic, mean*, pulse rate
- cranial tibial
- coccygeal
- median (large breed dogs)
What does Doppler BP measure? What artery is used?
systolic
median in small dogs and cats
What should the cuff size of BP measurements be? What general aspects are important for proper BP measurements?
30-40% limb circumference
- keep cuff level to the base of the heart
- multiple readings (accurate = close to one another)
- quiet environment and calm patient
- same site, cuff, and position (note in records!)
How can the white coat affect be avoided to improve accuracy of BP measurement in clinics?
- let the patient acclimate to the environment for about 10 mins
- measure BP before examination
- let owner be present
In what 3 instances is antihypertensive therapy considered?
- severe hypertension (systolic > 200 mmHg or diastolic > 120 mmHg)
- evidence of TOD with moderate to severe hypertension
- persistent elevated BP > 160 mmHg with evidence of clinical disease known to be caused or lead to hypertension
What is the “gray zone?”
moderately elevated systolic BP 160-180 mmHg without evidence of clinical disease or signs
When is hypertensive therapy not recommended?
mildly elevated BP 120-160 mmHg without clinical signs
What are the 2 aims to systemic hypertension treatment? What is the goal?
- control underlying diseases, like CKD, hyperthyroidism, HAC
- antihypertensive therapy - decreases CO, TPR
- avoidance of TOD
- close to 150 mmHg systolic
What is the first-line therapy of hypertensives for cats with increased BP?
calcium channel blockers —> Amlodipine
What is the first-line therapy of hypertensives for dogs with increased BP? What is another option?
RAAS inhibitors —> ACE inhibitors, Benazepril (less kidney excretion) and Enalapril = moderate decrease, Amlodopine can help too!
angiotensin receptor blocker —> Telmisartan
When are aldosterone antagonists recommended in patients with systemic hypertension? What is one example?
hyperaldosteronism, where increased aldosterone causes water and sodium retention which increases BP
Spironolactone
When are alpha antagonists recommended in patients with systemic hypertension? What are 2 examples?
pheochromocytomas that secrete catecholamines
- Phenoxybenzamine
- Prazosin
What 2 groups of drugs affect the cardiovascular system in patients with systemic hypertension?
- beta blockers - Atenolol
- direct vasodilators - Hydralazine (decreases BP acutely, used for emergencies)
What 2 alterations to diets help in patients with systemic hypertension?
- decreased caloric intake to induce weight loss in obese patients
- decreased sodium chloride
What 6 things should be monitored in patients with systemic hypertension?
- BP
- serum creatinine
- UA and UPC
- fundic exams
- tests for secondary disease management (aldosterone, T4, glucose)
- electrolytes
How often should patients be monitored for systemic hypertension?
- TOD present = 1-3 days
- TOD not present = 7-10 days
- stable = every 3 months
