Hypertension Flashcards
Define Hypertension as per Hypertension Canada Guidelines
HTN:
1) First visit - if BP greater than 180/110
2) Office BP measurements >130/80 for >3 measurements on different days ( consider to send for home monitoring to rule out WCH)
3) Home measurements of average daytime >135/85, or 24 hour BP >130/80
Normal BP across age span?
Normal Adult: 95-135/ 60-80 with some permissive ranges as adults get older (up to 145/90).
For Children (greater than one year of age) Median SBP = 90 mmHg + (2 x Age in years) Minimum SBP = 70 mmHg + (2 x Age in years)
Older children and adolescents should be a fairly classic 120/80 or slightly lower.
Just look up charts…
Factors effecting BP?
BP = Cardiac Output x Total peripheral resistance (blood viscosity and arteriolar radius)
Things that effect CO:
- anxiety
- eating
- exercise
- temperature
- pregnancy
- sympathetic activation
- position change
- heart pathology
What is the Frank-Starling Law and what does it have to do with hypertension?
Cardiac output is dependant on venous return - so when increased amounts of blood flow into the heart, the heart muscle stretches and this stretch (up to a point) allows for increased force of contraction.
This means that increasing CO can increase BP (to a certain point)
What are the rapid mechanisms of BP regulation?
Baroreceptor feedback:
- low pressure at pressure receptors in carotid sinus cause rapid activation of sympathetic system = vasoconstriction
CNS ischemic response
- more powerful sympathetic stimulation but only happens once MAP falls below 50mmHg
Chemoreceptors
- similar to baroreceptors but sense changes in pH, CO2 and to a lesser degree O2
What is the role of the renin-angiotensin-aldosterone system in hypertension?
This is a vasoconstriction mechanism initiated by the kidney, it is in response to LOW blood flow to the kidney.
Renin is released by the kidney - causes the activation of angiotensin 1 which is converted by ACE in the lung to angiotensin 2 which will help
- the kidneys retain water, (via aldosterone)
- systemic vasoconstriction
- Activates the pituitary to secrete ADH (antidiuretic hormone - aka vasopressin) to increase renal retention as well
What is the role of Atrial natriuretic peptide?
This is secreted by the atria of the heart in response to stretch. It is a high blood pressure response and acts opposite to the RAAS. It acts on the kidney to increase Na+ excretion and decrease water retention
Primary vs Secondary HTN?
Primary - elevated BP with no known underlying reason. May be environmental and genetic reasons.
Secondary - underlying cause that when corrected will fix hypertension
Consequences of severe HTN?
End-organ damage:
- hypertensive encephalopathy
- Aortic dissection
- ACS
- AKI
- Stroke
- Retinal damage
Look for: headache, chest pain, syncope, vision changes, abdominal pain
Target BP for non-diabetic? Target BP for diabetic?
Target BP non-diabetic = <140/90
Target BP diabetic = <130/80
Diuretic mechanism of action? Types of Diuretics?
Diuretics act to decrease extracellular fluid volume and vascular resistance
Thiazides (Hydrochlorothiazide), loop (furosemide), K+ sparing (spironolactone)
How do B-blockers work?
Decrease cardiac contractility and renin secretion
- careful in asthmatics/ CHF
- Propanolol and metoprolol
How do Calcium channel blockers work?
Decrease smooth muscle tone and cause vasodilation, my also act directly on the heart.
Caution with dihydropyridines - headache, flushing, peripheral edema - amlodipine
Non-dihydropyridines - verapamil, diltiazam
How do ACEI and ARBs work
Block aldosterone/ Angiotensin 2 production via the ACE
Hydralazine is?
A direct vasodilator which decreases peripheral resistance - use in emergency/ resistant BP
Alpha 1 antagonists?
doxazosin, terazosin
Decrease vascular tone, via blockage of NE receptors. Side effect of orthostatic hypotension. Not commonly used.
Methyldopa, clonidine are?
Are centrally acting adrenergic, inhibit the sympathetic nervous system via central alpha 2 agonists
Non-pharmacological management for HTN?
Physical exercise Weight reduction Alcohol consumption Diet Stress and sleep management
What is a pheochromocytoma?
Tumour of the adrenal gland, secretes too much NE and epinephrine
Presents with relapsing and remitting sx - HTN, pain (headache), perspiration, palpitations, pallor - check urine catecholamines
Treatment of hypertensive urgency and emergency?
Hypertensive urgency - severely elevated BP with no evidence of end-organ damage may have mild or moderate symptoms - treat with oral anti-hypertensives
Hypertensive emergency - severe elevation of BP with end-organ damage need to treat with IV medications
Drugs that can induce hypertension?
Alcohol, caffeine, cocaine, liquorice
Steroids, NSAIDS (blocking of COX stops inflammation mediated vasodilation and can infancy water retention), OCP, nasal decongestants
Consider Hyperaldosteronism in?
HTN with unexplained hypokalemia, multi-drug resistance, adrenal adenoma
Definition of gestational HTN?
Women who were previously normotensive - prior to pregnancy with >140/90 after 20th week gestation in the absences of proteinuria
Pre-eclampsia = same with proteinuria Eclampsia = same with seizures new onset
Do not use ACE or diuretics. Use methydopa or labetalol
Stages of hypertensive retinopathy
Grade 1: constriction of arterioles only
Grade 2: constriction and sclerosis of arterioles
Grade 3: Hemorrhages and exudates in addition to vascular changes (cotton wool spots)
Grade 4: Papilledema (obscuration of vessels, disk cupping, and a halo around the optic disk)
Primary aldosteronism triad
Hypokalemia, metabolic acidosis, hypertension
Tx of primary adrenal insufficiency
Fluids and corticosteroids, they can then be weaned from the corticosteroids but should be started on mineralocorticoids
Sx of HTN?
Vision change, headache, abdo pain, and altered mental status
How to calculate MAP
DBP + 1/3 (SBP-DBP)
SBP-DBP = pulse pressure
Greatest risk factor for HTN
Family Hx - first degree relative
Acute management of HTN crisis
Stabilize pt, get a CT non con to rule out bleed or mass - if none then the goal is not to decrease MAP more than 20-25% can do with IV labetalol (20mg) bolus can also use nicardipine
Contraindications of labetalol
Acute asthma, COPD, heart failure and heart failure and cocaine use
