13- Hypertension Flashcards
Primary or essential HTA?
The cause of blood pressure elevation is unknown. >90% HTA px
Secondary Hypertension
High blood pressure attributed to a definable cause
What pressure predicts more accurately cardiovascular complications?
Systolic
Stroke volume is determined by:
- Cardiac contractility
- Venous return to the heart
- The resistance the left ventricle must overcome to eject blood into the aorta (afterload)
What are the four systems responsible for blood pressure regulation?
- Heart
- Blood vessel tone
- Kidney
- Hormones
What is the normal sistolic/diastolic pressure?
<120/<80!
What are considered prehypertensive values?
120-139/80-89 mmHg
What is considered stage 1 hypertension?
140-159/90-99
What is considered stage 2 hypertension?
> 160/>100
In the presence of normally functioning kidneys, an increase in blood pressure leads to augmented urine volume and sodium excretion, which then returns blood pressure back to normal. This process is called:
Pressure natriuresis
What are the two possible reasons why pressure natriuresis is blunted in HTA patients?
- Microvascular and tubulointersticial injury within the kidneys which impairs sodium excretion
- Hormonal factors (RAA axis)
Which feedback mechanisms continuously monitor blood pressure?
Baroreceptors
Where can you find the baroreceptors?
Aortic arch and carotid sinus
How do baroreceptors monitor blood pressure?
By sensing stretch and deformation of arteries
How do baroreceptors regulate blood pressure?
They regulate bp by sending negative feedback via a Autonomic nervous system.
Signals of the carotid sinus are carried by:
Glosopharingeal nerve (IX)
Signals from the aortic arch are carried by:
Vagus nerve (X)
where do the glosopharingeal and vagus nerve converge?
Tractus solitarius
what do the baroreceptor impulses do in the tractus solitarius?
- inhibit sympathetic nervous system outflow
2. Excite parasympathetic effects
what is the net result of the baroreceptor impulses?
- decline in PVR (vasodilation)
2. reduction in CO (lower HR and reduced inotropism
what happens when baroreceptors sense a fall in systemic blood pressure?
fewer baroreceptor impulses are transmitted to the medulla leading to a reflexive increase in BP
why don’t baroreceptors prevent the development of chronic hypertension?
they regulate moment-by-moment variation of BP. After a day or two of exposure of higher than baseline pressure the baroreceptor firing rate slows back to its control value.
what is the most likely cause of EH?
a complex genetic disorder involving several loci.
what race is more frequently affected of EH?
blacks
how can the heart contribute to HTA?
through high CO-based HTA due to sympathetic over reactivity. (excessive HR acceleration in stressful conditions)
How can the blood vessels contribute to HTA?
they can by PVR based HTA by constricting in response to:
- increased sympathetic activity
- abnormal regulation of tone by NO, endothelin and natriuretic factors
- ion channel defects in contractile vascular smooth muscle
How can the kidney contribute to HTA?
it can induce volume based HTA by:
- failure to regulate renal blood flow
- ion channel defects
- inappropriate hormonal regulation
how are renin levels found in HT px?
25%: subnormal
60%: normal
10-15%: high
How should renin levels be in HT patients?
low
how does insulin play a role in the development of hypertension?
- increased sympathetic activation
2. vascular smooth muscle cell hypertrophy
How does obesity play a role in the development of hypertension?
- release of angiotensinogen from adipocytes
- augmented blood volume related to increased body mass
- increased blood viscosity caused by adipocyte release of pro fibrinogen and plasminogen activator inhibitor 1.
Where can the potential primary abnormalities in EH be found?
- blood vessels
- adrenal glands
- CNS
- Pressure and volume receptors
- Kidney
what functional and structural abnormalities of blood vessels could cause EH?
FUNCTIONAL
- less NO
- more Endothelin
- Ca++ or Na+/K+ channel defects
- Hyper-responsiveness to catecholamines
STRUCTURAL
-exaggerated medial hypertrophy
What abnormalities of Adrenal glands could be a cause of EH?
catecholamine leak or malregulation
What abnormalities of the CNS could be a cause of EH?
- Increased basal sympathetic tone
- abnormal stress response
- abnormal response to signals of baroreceptors and volume receptors
What abnormalities of the pressure/volume receptors could be a cause of EH?
Desensitization
What abnormalities of the kidney could be a cause of EH?
- RAA disfunction
2 Ion channel defects
at what age does the diastolic pressure begin to decline?
50
what is the hyperkinetic phase of EH?
high CO with normal PVR. Seen in younger px.
What abnormality is usually found in younger EH px?
elevated CO
What abnormality is usually found in older EH px?
elevated TPR
Why should we always screen for secondary HT?
1 they require different treatment
2 they can be cured often.
3 adaptative changes may cause chronic HT
What are the clues that a px may have a correctable condition (SHT)
- AGE: HT <20 or >50
- SEVERITY: often causes blood pressure to rise dramatically
- ONSET: presents abruptly in previously normotensive
- ASOCIATED SIGNS AND SYMPTOMS: eg Renal artery bruits
- FAMILY HISTORY: occurs sporadically
In the patient evaluation (history and physical) what clues should we look for to see if the pax has a secondary form of HT?
- recurrent UTI
- Excesive weight loss
- weight gain
- excesive acohol consumption
- medications
- obstructive sleep apnea
what lab tests should be performed in the initial evaluation of the HT patient?
- URINALISIS
- K+ serum levels
- blood glucose
- cholesterol
- EKG
HT px with recurrent UTI, you think of..?
chronic pielonefritis
HT px with excessive weight loss. you think of..?
pheochromocytoma
HT px with excessive weight gain, you think of..?
Cushing syndrome
What are the main causes of HT?
- essential
- Chronic renal disease
- primary aldosteronism
- Renovascular
- Pheochromocytoma
- Coartation of Aorta
- Cushing syndrome
what percentage of px are ESSENTIAL HT and what are the clues?
~90%
- age onset: 20-50 years
- family history of HT
- Normal serum K+, urinalisis
What % of HT patients are caused by CHRONIC RENAL DISEASE and what are the clinical clues?
2-4%
- rise in creatinine
- abnormal urinalisis
What % of HT px are caused by PRIMARY ALDOSTERONISM and what are the clinical clues?
<2-15%
-LOW SERUM K+
What % of HT px are caused by RENOVASCULAR DISEASE and what are the clinical clues?
1%
- abdominal bruit
- sudden onset (especially if <20 or >50)
- low serum K+
What % of HT px are caused by PHEOCROMOCYTOMA and what are the clinical clues?
- 2%
- paroxysms of palpitations, diaphoresis and headache
- weight loss
- episodic HT in 1/3 of px
What % of HT px are caused by COARCTATION OF THE AORTA and what are the clinical clues?
- 1%
- BP in arms> legs or right arm>left arm
- Midsystolic murmur between scapulae
- Chest X-ray: aortic indentation, rib-notching due to arterial collateral’s
What % of HT px are caused by CUSHING SYNDROME and what are the clinical clues?
- 1%
- “cushingoid” appearance (e.g. central obesity, hirsutism.)
What are the EXOGENOUS causes of HT?
- oral contraceptives
- glucocorticoids
- cyclosporine
- eryhtropoietin
- sympaticomimetic drugs
- NSAIDS
- Ethanol
- Cocaine
renal disease contributes to two important endogenous causes of secondary HT which are:
- renal parenchymal disease (2-4%)
2. renal arterial stenosis (1%)
How can renal parenchymal disease induce HT?
- increased Intravascular Volume
2. excessive elaboration of renin
What are the causes of renovascular HT?
- atheroesclerotic lesions
- fibromuscular lesions
- emboli
- vasculitis
- external compression of the renal arteries
RH ateroesclerotic lesions are most common in:
elder men
RH fibromuscular lesions are most common in:
young women
by what mechanism does RH evolve?
there is reduced renal blood flow therefore the kidney releases renin which raises blood pressure
what clinical findings suggests RH?
abdominal bruit or unexplained hipokalemia hypokalemia
what % of RH patients present abdominal bruit?
40-60%
where can we find ANG II receptors?
- arterial smooth muscle
- adrenal gland
- sympathetic nervous system
- kidney
- brain
- heart
what the function of ANG II receptors on arterial smooth muscle?
vasoconstriction
whats the function of ANG II receptors on the adrenal glands?
secretion of aldosterone (Na+ reabsorption in distal nephron, K excretion)
whats the function of ANG II receptors in the sympathetic nervous system?
facilitates release of norepinephrine (vasoconstrictor, raises TPR)
whats the function of ANG II receptors in the kidney?
raise renal tubular absorption of Na+
whats the function of ANG II receptors in the brain?
stimulates thirst and vasopresin secretion
whats the function of ANG II receptors in the heart?
ENHANCES CONTRACTILITY AND VENTRICULAR HYPERTROPHY
how can RH be corrected?
- percutaneus catheter intervention
- surgical reconstruction of a stenosed vessel
- Ace inhibitors (unilateral stenosis ONLY)
mechanical cause of HT?
Coarctation of the aorta
what could cause lower pressure in the left arm compared to the right arm?
coartation of the aorta that involves the origin of the left subclavian artery
by what mechanisms does coarctation of the aorta rise blood pressure?
- reduced blood flow to kidneys stimulates the renin angiotensin system
- high pressures proximal to the coarctation stiffen the aortic arch through medial hyperplasia and accelerated ateroesclerosis blunting the normal baroreceptor response to elevated intravascular pressure.
what are the clinical clues to the presence of coarctation?
- inadequate blood flow to legs or left arm
- claudication or fatigue
- weakened or absent femoral pulses
- midsystolic murmur
5 RX: indentation of the aorta - notched appearance of the ribs
treatment of coarctation of the aorta
angioplasty of surgery
*HT may not abate completely due to desensitisation of the baroreceptors
how can we evaluate endocrine causes of hypertension?
- HISTORY of characteristic signs and symptoms
- measurement of hormone levels
- Assessment of hormone secretion in response to stimulation inhibition
- imaging studies to identify tumours secreting the excessive hormone.
what are the endocrine causes of hypertension?
- pheocromocytoma
- Adrenocortical Hormone Excess
- Thyroid hormone abnormalities
what are pheocromocytomas?
Catecholamine secreting tumours of neuroendocrine cells (usually in the adrenal medulla)
what % of hypertension is caused by pheochromocytomas?
0.2%
what is the characteristic presentation of a pheochromocytoma?
paroxysmal rises in blood pressure with “autonomic attacks”
What are “autonomic attacks”?
- severe throbbing headaches
- profuse sweating
- palpitations
- tachycardia
caused by the increased catecholamine levels in pheochromocytomas
what % of pheochromocytomas are malignant?
10%
what lab tests are used to determine pheochromocytomas?
- plasma cathecolamine levels
2. urine catecholamines and their metabolites (vanillylmandelic acid and metanephrine)
What is the pharmacologic therapy of pheochromocytomas?
alpha receptor blocker + Beta blocker
once located= surgical resection
what imaging techniques can be used to localise a pheochromocytoma?
- computed tomography
- magnetic resonance imaging
- angiography
whats the treatment for inoperable pheochromocytomas?
alfa block, beta block and drugs that inhibit catecholamine biosynthesis
What adrenocortical hormones can produce HT when found in excess?
- mineralocorticoids
2. glucocorticoids
what is an important marker of mineralocorticoid excess?
HIPOKALEMIA
what is the mechanism of hypertension due to mineralocorticoid excess?
aldosterone increases blood volume by stimulating reabsorption of Na+in exchange for K excretion.
Primary Aldosteronism results from:
- adrenal adenoma (conn syndrome)
2. Bilateral hyperplasia of the adrenal glands
what is Conn syndrome?
adrenal adenoma that results in primary aldosteronism
whats the frequency of primary aldosteronism amongst hypertensives?
10-15%
the majority of hypertensives with primary aldosteronism have:
bilateral hyperplasia of the adrenal glands
how can primary aldosteronism be diagnosed?
suspected by: hypokalemia
dx by: excessive plasma aldosterone levels + suppressed renin
what is the treatment of primary aldosteronism?
- surgical removal of adenoma (if present)
2. aldosterone receptor antagonists
what is Glucocorticoid remediable aldosteronism?
HAD form of primary aldosteronism where aldosterone synthesis comes under the regulatory control of ACTH.
How does glucocorticoid remediable aldosteronism present?
severe hypertension in childhood or young adulthood
non GRA primary aldosteronism is seen most commonly in what ages?
30-60 YRS OLD
Tx of GRA?
glucocorticoids suppress ACTH release from the pituitary gland
secondary aldosteronism can result from:
- rare renin secreting tumors
- oral contraceptives
- chronic liver disease
mechanism of secondary aldosteronism HT by RENIN SECRETING TUMORS
increased ANG II
mechanism of secondary aldosteronism HT by ORAL CONTRACEPTIVES
SECONDARY ELEVATION OF ALDOSTERONE AS A RESULT OF AUGMENTED CIRCULATING ANG II DUE TO HEPATIC STIMULATION TO PRODUCE ANGIOTENSINOGEN
mechanism of secondary aldosteronism HT by CHRONIC LIVER DISEASE
impaired ANG II degradation
what is the mechanism of HT due to glucocorticoid excess?
cortisol elevates blood pressure via blood volume expansion and stimulated synthesis of components of the renin-ang system.
Additionally the can activate renal tubules like mineralocorticoids
what % of px with Cushing Syndrome present HT?
80%
What are the classic cushingoid features?
- rounded face
- central obesity
- proximal muscle weakness
- hirsutism
What are the causes of cushing syndrome?
- pituitary ACTH secreting adenoma
- peripheral ACTH-secreting tumor
- Adrenal cortisol-secreting adenoma
How is the diagnosis of cushing syndrome confirmed?
24 hour collection of urine or a dexamethasone test
what proportion of Hyperthiroids present HT?
1/3
WHAT % of hypothyroids have HT?
1/4
How do Thyroid hormones exert their cardiovascular effect?
- inducing sodium potassium ATPases in the heart and vessels
- increasing blood volume
- stimulating tissue metabolism and oxygen demand w. secondary accumulation of metabolites that modulate local vascular tone.
mechanism of HT in Hypothyroid px
they have predominantly diastolic HT + increase in TPVR (sympathetic + adrenal activation)
what are the most common symptoms found in HT px?
- flushing
- sweating
- blurred vision
HT complicated with atheroesclerosis can manifest through:
arterial bruits
HT organ damage can be attributed to
- increased workload of the heart
2. arterial damage resulting from combined effects of the elevated pressure itself and accelerated atheroesclerosis
what abnormalities of the vasculature can result from elevated blood pressure?
- smooth muscle hypertrophy
- endothelial cell disfunction
- fatigue of elastic fibers
chronic HT trauma to the endothelium promotes atheroesclerosis by:
disrupting normal protective mechanisms ( secretion of NO)
What organs are mainly targeted by Ht?
- heart
- cerebrovascular system
- the kidney
- the retina
If left untreated HT px die of:
- 50% CAD or congestive heart failure
- 33% stroke
- 10-15% complications of renal failure
what are the manifestations of organ damage in the HEART?
- left ventricular hypertrophy
- Heart failure
- myocardial isquemia and infarction
What are the manifestations of HT organ damage of the cerebrovascular system?
stroke
what are the manifestations of organ damage of HT in the AORTA AND PERIPHERAL VASCULAR SYSTEM?
- aortic aneurism
2. arterioesclerosis
what are the manifestations of organ damage of HT in the KIDNEY?
- nephroesclerosis
2. renal failure
what are the manifestations of organ damage in the RETINA?
- arterial narrowing
2. hemorrhages, exudates, papilledema
what kind of heart hypertrophy is the normal pattern of compensation when high arterial pressure increases the wall tension?
concentric hypertrophy w/o dilatation
what kind of heart hypertrophy is seen in conditions where increased circulating volume increases wall tension?
Eccentric hypertrophy with chamber dilatation
left ventricle hypertrophy results in:
- increased LV stiffness
- diastolic disfunction
- elevated filling pressures (pulmonary congestion)
what are the physical findings of left ventricular hypertrophy?
- heaving LV impulse on chest palpation
2. 4th heart sound (stiff LV)
the degree of cardiac hypertrophy correlates with:
- congestive heart failure
- angina
- arrhythmia’s
- myocardial infarction
- sudden cardiac death
what are the findings of systolic disfunction?
- reduced CO
2. pulmonary congestion
systolic disfunction is provoked by:
- failure to balance high wall tension caused by the elevated pressure
- myocardial ischemia due to accelerated CAD
What post infarct complications are present in HT px?
- rupture of the ventricular wall
- LV aneurysm formation
- congestive heart failure
what % of px who die of transmural infarctions have history of HT?
60%
HT induced stokes can be:
- hemorragic
2. atherothrombotic (most common)
what are lacunar infarctions?
< 3mm cavities
Where are most lacunar infarctions found?
in the penetrating branches of the middle and posterior circulation of the brain
mechanism of formation of “watershed” infarcts?
there is a generalised arterial narrowing due to HT which leads to hipoperfusion specially if there is a sudden BP drop.
Where are abdominal aortic aneurisms (AAA) usually located?
below the renal arteries
aneurisms greater than 6 cms have a very high likelihood of rupture within:
2 years
what is the mortality of an aortic dissection?
> 90%
what do yo call hypertension induced kidney disease?
nephroesclerosis
when vessel walls become infiltrated by a hyaline infiltrate it is known as:
hyaline arterioesclerosis
what changes in HT lead to reduced vascular supply and ischemic atrophy of the renal tubules?
- smooth muscle hypertrophy
- necrosis of the capillary walls (fibrinoid necrosis)
- hyaline arterioesclerosis
one of the consequences of HT renal failure is:
perpetuation of elevated blood pressure
what is the only location where the arteries can be directly visualised by physical examination?
the retina
hypertensive retinopathy serves as:
an asymptomatic clinical marker for the severity of HT and its duration
ACUTE severe HT leads to what retinal findings?
- haemorrhages, exudation of plasma lipids
- areas of local infarction
- papiledema
ischemia of the optic nerve leas to:
generalized blurred vision
retinal ischemia due to hemorrage leads to :
patchy loss of vision
CHRONIC svere HT has the following retinal findings:
- arterial narrowing (vasoconstriction)
- medial hypertrophy (arteries indent crossing veins)
- arterial sclerosis (copper or silver wiring)
copper/silver wiring evidences:
arterial sclerosis
indentation of veins of the retina evidence:
medial hypertrophy
a Hypertensive crisis is usually caused by:
an acute hemodinamic insult (acute renal disease) superimposed on a chronic hypertensive state
a px with severe HT + headache, blurred vision, confusion, somnolence or coma probably is developing:
hypertensive encefalopathy
when hypertension results in acute damage of the retinal vessels the patient is said to be presenting:
accelerated malignant hypertension
how can an acute hemodinamic insult like acute renal disease worsen a hypertensive state?
by increasing volume expansion and vasoconstriction because renal perfusion is dropping and serum renin and angiortensin levels rise`
the increased load on the LV during a hypertensive crisis may precipitate:
an angina or pulmonary edema
after a hypertensive crisis is treated correctly:
there is reversal of the acute pathologic changes (papiledema and retinal exudation)
renal damage often persists
what is the additional risk of stroke in a person with stage 1 HT?
1/850
what are the lifestyle modifications used as a nonpharmacologic treatment of HT?
- weight reduction
- exercise
- diet
- lower sodium intake
- higher potassium intake
- decrease chronic alcohol intake
- smoking cessation
- relaxation therapy
blood pressure reduction follows weight loss in a rye portion of hypertensives who are more than what % above of their ideal weight?
10%
each 10kg of weight loss is associated with ___mmHg fall in systolic blood pressure
5-20mmHg
normotensive sedentary people have ____ higher risk of developing HT.
20-50%
what kind of diet composition has been shown to beneficial for BP reduction
Diet high in fruits, vegetables and low fat diary products
what % of EH px have been found to have BP that vary with Na+ intake?
50%
sensitivity to Na+ is more common in :
african american and elderly
what is the current recommendation of sodium chloride intake?
<6gr per day
what deficiencies have been found to be associated with higher BP?
Mg. K+ and Ca++
chronic consumption of alcohol correlates to
resistance to antihypertensive medications
Caffeine ingestion transiently increases BP as much as:
5-15mmH
Why does cigarette smoking transiently increase BP
nicotine effect un autonomic ganglia
cigarettes atherogenic effect may contribute to the development of:
renovascular HT
in what 4 classes do most antihypertensive medications fall in?
- Diuretics
- Sympaticolitics
- Vasodilators
- Drugs that interfere with the renin-angiotensin system
how can diuretics help lower BP?
They reduce circulatory volume, CO and mean arterial pressure.
Diuretics are most effective in what type of HT?
mild to moderate HT
Diuretics are specially effective on what pxs?
AFRICAN AMERICAN AND ELDERLY(salt sensitivity)
what are the most common diuretics use in HT?
thiazide
What diuretics are usually only used in renal insufficiency?
loop diuretics
which diuretics promotes Na+ excretion through the distal nephron
thiazide and potassium sparing diuretics
what are the side effects of thiazides?
- elevation of serum glucose
- cholesterol
- triglycerides
- hypokalemia
- hyperuricemia
- decreased sexual function
what is the subclasification of sympaticolitic agents?
- B blockers
- central alfa adrenergic agonists
- systemic alfa adrenergic blocking drugs
By what mechanisms do B blockers reduce BP?
- reducing CO (<hr>
are B blockers less effective in elderly and african americans
yes
what are the side effects of B blockers?
- broncospasm
- fatigue
- impotence
- hyperglycemia
- > tryglicerides and
what types of B blockers do not alter HDL levels?
combined alfa and beta blockers (labetalol)
examples of centrally acting alfa 2 adrenergic agonists?
methyldopa and clonidine
whats the mechanism of action of centrally acting alfa 2 adrenergic agonists to lower BP?
they reduce sympathetic outflow to the heart, blood vessels and kidneys
why are centrally acting alfa 2 adrenergic agonists rarely used?
because of the high frequency of their side effects (dry mouth, sedation)
examples of systemic alfa 1 antagonists
prazozin, terazosin and doxazosin
how do systemic alfa 1 adrenergic antagonists lower BP?
what type of sympatholitic agents are only useful in older men and why?
systemic alfa 1 antagonists, they also improve symptoms of prostatic enlargement.
(greater number of adverse cv effects)
whats the subclasification of peripheral vasodilators?
- Ca++ channel blockers
- hydralazine
- minoxidil
how do Ca++ channel blockers induce vasodilation?
they reduce the Ca++ influx responsible for cardiac and vascular smooth muscle contraction, reducing cardiac contractility and TPR.
how do Hydralazine and Minoxidil work?
by directly relaxing vascular smooth muscle of pre capillary resistance vessels
Why do Hydralazine and minoxidil have to be combined with B blockers?
because of the reflex increase in HR
Name the three types of drugs that interfere with the renin-agiotensine aldosterone system
- ACE inhibitors
- ang II receptor blockers
- direct renin inhibitors.
how do ACE inhibitors decrease BP?
by blocking conversion of ANG I to ANG II, therefore reducing vasopressor effect of ANG II and the secretion of aldosterone. bradikinin
ACE inhibitors have been shown to reduce mortality of which px?
- acute MI
- chronic symptomatic systolic heart failure
- px at high risk of CV disease
Can ACE inhibitors slow the deterioration of the renal function in px with diabetic nephropathy?
yes
which antiHT develop reversible dry cough and why?
ACE inhibitors, due to release of bradikinin
what are the side effects of ACE inhibitors?
dry cough, hyperkalemia, azotemia
How do ang II receptor blockers (ARBs) lower BP?
they block the binding of ANG II to its receptors in blood vessels and other targets
In clinical trials what other antiHt medications are said to be similar to ARBs?
ACE inhibitors
which is the most recent group of antiHT introduced?
oral direct renin inhibitors
how does direct renin inhibitors work?
THEY INHIBIT THE BINDING OF ANGIOTENSINOGEN TO RENIN
the JNC establishes which medication as a first line treatment for uncomplicated HT?
thiazide diuretics
In the following px which HT medication would be suitable?
- heart failure
- diabetes
- LV disfunction following MI
ACE inhibitor
what HT medication would be suitable for a paint with concurrent ischemic disease?
B blocker
what HT medication would be probably used in a young person?
B blocker
what type of HT medication would be probably used in a elder person?
vasodilator (long acting calcium inhibitor)
why are direct vasodilators paired with a low dose diuretic?
because vasodilators can activate the RAA axis leading to volume retention