Flashcards in Overview of Hypertension Deck (21):
3 key features of all hypertension (HTN)?
Systemic arterial pressure is at sustained increased levels.
SVR is too high, and too much Na+ and H2O is retained.
2 broad groups of hypertension?
Primary (essential) HTN - resistance or compliance HTN.
Why is HTN bad for the LV?
Increased afterload means LV has more wall stress -> hypertrophy, fibrosis -> impaired diastolic relaxation and general function.
Why is HTN bad for the arterial system?
Increased pressure -> increased wall stress.
Aneurysms, accelerated atherosclerosis.
Esp. obliterative destruction of systemic arterioles -> higher SVR -> more HTN.
Why is HTN bad for the kidney?
HTN is made worse because reduced GFR -> reduced ability to excrete sodium.
How does blood pressure change with age?
With increasing age, there's increasing BP, especially systolic BP.
Is there a threshold effect for the relationship between BP and morbidity/mortality?
Nope, it's pretty much continuous (until you hit hypotension) - where lower is better.
What might drive much of the hypertension in modern society?
What are the cut offs for classifying normal, prehypertension, stage 1 HTN, and stage 2 HTN?
Normal: < 120 systolic, and < 80 diastolic.
Prehypertension: 120 - 139 SBP, or 80-89 DBP.
Stage 1 HTN: 140 - 159 SBP, or 90-99 DBP.
Stage 2 HTN: >160 SBP, or >100 DBP.
(note that whether these line up with thresholds for treatment depends on concurrent risk factors, eg. with diabetes one might treat at 130/90.)
4 mechanisms for secondary hypertension?
Adrenal disease (primary aldosteronism, Cushing's, pheochromocytoma).
CNS (corticotroph pituitary adenoma -> ACTH)
What are 3 mechanisms that should prevent hypertension?
RAAS should shut off.
Are there racial/ethnic differences in HTN prevalence?
Yep. Higher in African-Americans, Africans in the UK, and Asians...
(heredity or environment?)
Does Na+ restriction work well for HTN?
Yes, very well. But it's hard to get people to do it..
Does stress increase BP?
Does alcohol increase BP?
How do blood pressures vary between resistance hypertension and compliance hypertension?
Resistance HTN: problem is w. regulation of SVR -> increase in both systolic and diastolic BP.
Compliance HTN: problem is loss of compliance in great vessels "stiff pipes" -> increase in systolic BP, but diastolic BP is normal to low.
Consequences of compliance HTN?
Severe LV pressure overload ->
Aneurysms (in aortic and brain)
Describe the deWardener & MacGregor model for essential HTN.
Normally, when plasma volume is expanded, a natriuretic peptide (not identified) inhibits Na+/K+ pumps... in the kidney, this causes Na+ excretion.
However, in pts with HTN, the kidneys don't respond normally, so natriuretic peptide levels stay high. Na+/K+ pumps on vascular smooth muscle cells are blocked. Na+ buildup intracellularly -> activation of Na+/Ca++ exchanger -> Ca++ buildup -> more vascular smooth muscle contraction -> increased SVR and BP.
So... what's the deal with this mysterious natriuretic peptide?
Still not found. It's not any of the atrial natriuretic peptides.
Ouabain may be an analogue of it.
In HTN, renal sympathetics might be overactive.