Hypertension/Hypotension Flashcards
What are the 3 categories of hypertension
- Situational
- Idiopathic
- Secondary
List causes associated with the development of systemic hypertension in cats and dogs. Which one is the main cause?
Diseases:
- CKD
- AKI
- Diabetes mellitus
- Hyperadrenocorticism
- Hyperthyroidism
- Pheochromocytoma
- Hyperaldosteronism
Toxins / medications:
- Glucocorticoids
- Mineralocorticoids
- Erythropoiesis-stimulating agents
- Phenylpropanolamine
- Phenylephrine
- Ephedrine
- Methamphetamine
- Cocaine
Main cause = kidney disease (chronic and acute)
What are the main hormones involved in pathogenesis of hypertension
- Catecholamines (increase systemic vascular resistance)
- Angiotensin II (increases systemic vascular resistance and causes sodium and water retention)
- Aldosterone (causes sodium and water retention)
- Cortisol (increases vascular reactivity to catecholamines)
Other mediators involved: endothelin, thromboxane, NO, prostacyclin, histamine
What are the organs mostly affected by systemic hypertension (target organ damage)
- Eyes
- Kidneys
- Brain
- Cardiovascular system
Describe ocular lesions secondary to systemic hypertension
- Retinal detachment
- Tortuous vessels
- Retinal hemorrhage
- Edema
- Acute blindness, mydriasis
List possible clinical signs of hypertensive encephalopathy
- Mentation change
- Disorientation
- Seizures
- Vestibular signs
What is the classification of systemic hypertension
Based on TOD:
- Normotensive: < 140 mmHg (minimal TOD risk)
- Prehypertensive: 140-159 mmHg (low TOD risk)
- Hypertensive: 160-179 mmHg (moderate TOD risk)
- Severely hypertensive: >180 mmHg (high TOD risk)
What is a hypertensive crisis? Hypertensive urgency?
Hypertensive crisis = presence of severe hypertension (>180 mmHg) with evidence of TOD (mostly ocular or neurological)
Hypertensive urgency = significant increase in BP without TOD
What is the therapeutic goal for management of hypertensive crisis
Reduction in SBP of 10% over first hour then 15% over next several hours
Name medications potentially used for hypertensive crisis
Fenoldopam, nitroglycerine, nitroprusside, hydralazine, labetalol
What is the first line treatment at home for systemic hypertension associated with renal disease in dogs and cats?
Dogs: ACE inhibitor first line +/- calcium channel blocker
Cats: calcium channel blocker first line +/- angiotensin receptor blocker
Why should the use of calcium channel blocker as mono therapy in dogs be avoided?
Because CCB preferentially dilate the renal afferent arteriole potentially exposing the glomerulus to damaging increases in glomeru- lar capillary hydrostatic pressure
- whereas ACEi preferentially dilate the efferent arteriole
How many measurements are required to diagnose hypertension
If TOD is present, hypertension can be diagnosed with one measurement. Otherwise, should be confirmed on > 2 measurements taken over 4-8 weeks for prehypertension and moderate hypertension, or over 1-2 weeks for severe hypertension.
When should antihypertensive therapy be initiated? What is the therapeutic goal?
When SBP>160 mmHg, goal is to get SBP<160 mmHg (ideally <140 mmHg)
How does hypertension develop in the context of kidney disease?
Multifactorial:
- Progressive nephron loss can trigger RAAS activation in attempt to improve GFR, AT II preferentially causes efferent arterial vasoconstriction
- Decreased renal blood flow triggers activation of SNS
- Chronic endothelial dysfunction results in decreased production of NO
What are the main vasopressor drugs, where do they act and what is their effect?
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