Hypertension Overview 9/10/2014 Flashcards
(30 cards)
T/F: HTN is a disease
false: it is a syndrome that encompasses a large group of disorders
HTN is fundamentally a disorder of regulation of ________.
Systemic Vascular Resistance
HTN is believed to be the end product of the interaction of what 3 concepts?
-hereditary, environment, behavior
3 broad manifestations of HTN
- SAP is regulated at a sustained abnormally high level
- abnormal regulation of Na and body fluid metabolism
- abnormal fibrosis (deposition of collagen) in tissues
2 broad categories of hypertension
- primary (essential HTN) which can be resistance HTN or compliance hypertension (stiff pipes seen in old age)
- secondary HTN
3 big areas of detrimental consequences of HTN
- LV: generates a higher systolic P which increases LV wall stress in systole, causes LV hypertrophy (concentric), generalized fibrosis in myocardium that decreases LV diastolic compliance=impaired relaxation (diastolic dysfunction)
- arterial system: increase wall stress in SA system; arterial vascular disease (aneurysms, accelerates atherosclerosis), arteriolar disease: obliterative destruction which increases SVR even more
- Kidney: due to arteriolar destruction which further decreases ability to excrete Na
What is the most common cause of chronic renal failure?
-HTN causing obliteration of systemic arterioles including those in the kidney
4 main clinical consequences of HTN
- cardiac dysfunction due to progressive LVH and fibrosis: CHF
- accelerated atherosclerotic and aneurysmal disease of large-medium systemic arteries: MI, stroke, aneurysms increase
- progressive destruction of systemic arterials= increase SVR
- renal dysfunction secondary to renal destruction of arterioles: contributes to excess Na retention
Worldwide prevalence of HTN and the excess death rate people with it carry
- 1 billion people
- about 1% increase per year
CV morbidities associated with HTN
- CAD, Peripheral vascular disease, stroke, CHF
- all go up as severity of either systolic or diastolic HTN increases
Blood pressure and age
-thought to be normal that there is an age related increase with BP; systolic more so than diastolic and this means pulse pressure increases with age
Problems with the definition of hypertension
- epi: continuum of BP values in the population, disorder is so prevalent that it may appear normal, tendency for increase with age
- morbidity: continuum of frequency of morbidity with BP
When it comes to BP, ______ is always better!
-lower
Normal, preHTN, stage 1 and stage 2 HTN cut offs
Normal: / 160 or >/100
Primary vs Secondary HTN
primary: no identifiable cause linked to a particular organ system
secondary: caused by a disorder of 1 of the arterial pressure regulatory mechanisms: kidney disease, adrenal disease, CNS disease, drug intake
3 mechanisms which should prevent HTN but malfunction
- baroR reflex: reset to higher threshold
- pressure-natruiresis in kidney does not function appropriately
- RAAS: does not shut off renin as it should–some pts have ACE mutations
In what societies do we not see an increase in HTN prevalence with age?
-societies with low sodium diets–Yanomano Indians of SA
Impact of dietary sodium intake on HTN prevalence
- 1 tsp (<2 g/d is idea) but only 3.3% of world does this
- for each increase of salt intake (per g) BP increases more.
Dahl R and S rats and the significance
- R rats remained normotensive at high Na diet
- S rates developed severe HTN and died early on; had less renal Na output at any level of arterial inflow pressure
- impact of genetics
The Rice Diet
- diet virtually free of sodium fed to severely HTN patients
- produced dramatic reductions of BP with resolution of many abnormalities
- showed the beneficial effect of Na restriction
Factors other than Na intake known to influence prevalence of HTN
- environmental stress: HTN more prevalent in urban than rural pops; genetically predisposed individuals have a more pronounced vasoC response to stress than normals (seen in renovasculature)
2. obesity
3. physical inactivity: exercise reduces BP
4. alcohol consumption
Resistance vs Compliance HTN
- resistance: fundamental abnormalities is abnormal regulation of vascular resistance. SVR is elevated. Systolic, diastolic, and MAP are all elevated, pulse pressure is modestly elevated. Typical arterial P is 150/100
- compliance: issue = decreased great vessel compliance. SVR is normal or slightly elevated. Systolic P is elevated, diastolic is normal or low, MAP is modestly elevated. Pulse pressure is greatly elevated (due in part to inc pulse wave velocity). typical arterial pressure is 170/60
Consequences of compliance HTN
- severe LV P overload
- causes severe LVH (decreased LV diastolic compliance, causing diastolic HF– HFpEF)
- accelerated vascular disease: aortic aneurysms, Cerebrovascular dz
“Vicious Cycle” in HTN
- initial effects: increase total body Na, increase SVR
- subsequent effects: destroy systemic arterioles (inc SVR), lose functioning renal mass, tissue fibrosis (cannot excrete Na)
- consequences: progressive increase in SVR, progressive loss of renal function and ability to excrete Na, increase CV load (heart and arterial system), changes in LV systolic and diastolic properties
