Systemic Arterial Hypertension Flashcards
describe causes of hypertension
- situational hypertension/white coat syndrome
- pathologic hypertension:
a. secondary hypertension: caused by disease or medication
-cats: kidney disease (acute or chronic), hyperthyroidism, medications
-dogs: hyperadrenocorticism, kidney disease (acute or chronic), medications
b. idiopathic hypertension: primary or essential in people and up to 20% of hypertensive cats
describe systemic arterial hypertension
- sustained, pathological increase in systemic arterial blood pressure
- common in animals with CKD (>20% of affected animals, can happen in any disease stage)
- hypertension may or may not resolve after recovery from AKI
describe the proposed mechanism for systemic arterial hypertension in CKD
- alterations in sodium handling
- activation of RAAS
- excessive sympathetic activity
all cause
4. sodium and water retention and arteriolar vasoconstriction
which causes
5. increased blood volume, CO, and systemic vascular resistance
what 4 organs are particularly susceptible to damage fro hypertension?
- eyes: retinopathy/choroidopathy/optic neuropathy
- kidneys: proteinuria, progression of CKD
- heart: left ventricular hypertrophy/arrhythmias/murmur vasculopathy
- brain: hypertensive encephalopathy/stroke
this damage can be silent!!
describe hypertension and the cardiovascular system
- evidence of cardiovascular target organ damage you might see in hypertensive animals:
-systolic murmur
-gallop sound
-left ventricular concentric hypertrophy
-vascular lesions (both micro and macroscopic)
describe hypertension and the brain
can cause:
- lethargy
- seizures
- altered mentation
- altered behavior
5, vestibular signs
describe hypertension and the eye
- retinal vascular tortuosity
- retinal hemorrhage or edema
- vitreal hemorrhage, secondary glaucoma
- partial or complete bullous detachment
describe hypertension and the kidneys
- balance between helping to control blood pressure and also being highly susceptible to hypertension-mediated damage
- animals with CKD are particular susceptible to hypertension-mediated renal damage bc their autoregulation is already not 100%
- systemic hypertension can increase the intraglomerular filtration pressure and lead to proteinuria
how do you diagnose hypertension?
- need to obtain a blood pressure measurement that you TRUST
- BP measurement can be altered by
-operator
-size of the cuff
-position of animal
-limb versus tail
-BCS/MCS
-stress/anxiety
-environment
-equipment - technique:
-acclimation before exam
-owner present for most
-laying or sitting
-tail or limb cuff 30-40% diameter; take 5-7 measurements and discard the 1st and any outliers
-average the measurements
-record everything! and repeat exact same conditions every time!!
-if using doppler, make it easier by shaving area (quiet clippers) and use headphones - interpret
-normotensive: <140
-prehypertensive: 140-159
-hypertensive: 160-179
-severely hypertensive: 180 or greater
-exception! sighthounds have higher in hospital BP than other breeds - final classification should rely on MULTIPLE measurements during repeated patient visits (AKA need more than one good measurement to diagnose)
describe treatment indications for each BP category
- normotensive (<140): no treatment
- prehypertensive (140-159): only treat if convincing target organ damage
- hypertensive (160-179) or severely hypertensive (>180): YES esp if repeatable measurement or convincing target organ treatment
if heart rate, stroke volume, blood volume, or inotropy are responsible for arterial hypertension, how do you treat?
use beta blockers and diuretics to activate renin release, but this may worsen glomerular hypertension! and diuretics also promote prerenal volume depletion
so these are not great options
describe calcium channel blockers to treat arterial hypertension
- block influx of calcium through L-type calcium channels to reduce calcium influx into cardiac or smooth muscle cells
- 2 categories:
-non-dihydropyridines: cardiac effects tat slow conduction and contractility (antiarrhythmic drugs)
-dihydropyridines: vascular effects that smooth muscle relaxation and vasodilation (antihypertensive drugs)
describe amlopidine
- L-type calcium channel blocker (dihydropyridine) with selectivity for vascular tissue
- reduces calcium influx into cell to cause vascular smooth muscle relaxation and vasodilation to result in decreased systemic resistance
- pharmacology: long half life, DOA up to 24 hrs
-highly efficacious: good choice for severe hypertension
-widely used in vet med(1st line therapy in cats) - possible adverse effects:
-hypotension
-bradycardia
-gingival hyperplasia (reversible)
-peripheral edema (rare) - contraindications:
-hypotension
-dehydration
describe RAAS inhibitors
- considered by may the first-line therapy for dogs and second-line for cats
-include angiotensin receptor blockers and ACE inhibitors - see proteinuria lecture for how these drugs work
- ARB have greater antihypertensive efficacy than ACEi
describe ideal antihypertensive treatment
- easy to administer
- inexpensive
- effectively lowers blood pressure
- prevents deterioration of kidney function
- treats glomerular hypertension
- reduces proteinuria
- reduced activation of RAAS
but perfect does not exist