22 Hypertension Flashcards
Hypertension
- Frequency
- Pt awareness, treatment, & control
- BP treatment
- Frequency
- Common in the US (1/3 of adults)
- Increases w/ age
- Affects both genders
- Pt awareness, treatment, & control
- 79.6% are aware they have hypertension
- 70.9% are being treated
- 47.8% have controlled BP
- BP treatment
- BP is a continuous variable so when to treat varies
- <60yo, CKD, or diabetes: goal < 140/90
- >60yo: goal < 150/90
Hypertension severity
- HTN is associated with…
- As ppl live longer due to decreased death from MI and CVA…
- As a primary disease, HTN accounts for…
- Risk of ESRD is associated w/…
- Management & risk of HTN
- Who’s at risk for developing HTN
- HTN is associated with…
- Significant morbidity & mortality
- Esp cerebrovascular accidents, coronary disease, & renal disease
- HTN control decreases cerebrovascular accidents (hemorrhagic or ischemic brain damage) & coronary artery disease.
- As ppl live longer due to decreased death from MI and CVA…
- They develop the next generation of diseases associated w/ HTN (CHF & renal failure) at an accelerating rate
- As a primary disease, HTN accounts for…
- 30% of the ESRD in the US
- Risk of ESRD is associated w/…
- Ethnicity
- Severity of HTN
- Management & risk of HTN
- Most common reason for physician visits by non-pregnant adults in the US
- Who’s at risk for developing HTN
- 90% of adults >50yo
Pathogenesis of HTN:
Definitions
- Arterial pressure
- HTN
- HTN in adults < 60yo
- HTN in adults > 60yo
- Arterial pressure
- Determiend by CO & systemic vascular resistance (SVR)
- BP = CO * SVR
- HTN
- Imbalance b/n CO & SVR
- Occurs when CO &/or SVR (peripheral resistance) increases
- HTN in adults < 60yo
- BP > 140/90
- HTN in adults > 60yo
- BP > 150/90
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Pathogenesis of HTN:
Cardiac output
- Rare to find a form of HTN where…
- Essential (primary) HTN
- Any sustained rise in BP requires…
- Role of genetics
- Sibling of pt w/ HTN
- Single gene defects
- Other genes associated w/ HTN
- HTN transplant
- Role of excess Na intake
- Salt vs. HTN/BP
- Essential HTN
- Rare to find a form of HTN where…
- Only one of either CO or SVR is abnormal
- Even in secondary forms of HTN multiple factors play a role
- Essential (primary) HTN
- 90-95% of all HTN
- Cause: multifactorial
- Any sustained rise in BP requires…
- Participation of the kidney
- Role of genetics
- Sibling of pt w/ HTN has 3.5x risk of HTN than general population
- Rare instances of single gene defects causing HTN exist
- Involve increased Na reabsorption due to a primary defect in a Na transport system (e.g. Liddle’s Syndrome affecting ENaC)
- Other genes associated w/ HTN
- Polygenic (multiple genes involved)
- Polymorphisms of ACE & RAAS genes
- HTN can be transplanted (Salt Sensitive Dahl rat)
- Role of excess Na intake
- Salt vs. HTN/BP
- Increase salt intake –> increase frequency of HTN
- Dietary Na restriction –> decreased BP
- Essential HTN
- Due to an abnormal kidney that’s unwillingn to excrete sodium
- Salt vs. HTN/BP
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Pathogenesis of HTN:
Primary increase in CO
- Guyton’s animal models
- Application of Guyton’s model to pts w/ reduced renal function
- Guyton’s animal models
- Decreased renal mass + volume expansion (i.e., give salt & water) –> BP increases due to increased CO
- Normal kidney function: CO returns to baseline in a few days
- Reduced kidney function: BP remains elevated due to increased peripheral vascular resistance
- Due to autoregulation in vascular beds
- Increased CO –> increased delivery to vascular bed –> increased total peripheral resistance –> return nutrient & oxygen delivery to vascular bed back to “normal”
- Application of Guyton’s model to pts w/ reduced renal function
- Young HTN pts: CO remains w/ normal TPR
- After years of chronic BP elevation due to chronic high salt intake, CO decreases to low levels but TPR increases
- Due to cardiac and vascular remodeling
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Pathogenesis of HTN:
Cardiac output:
Abnormality in Na excretion (4 hypotheses)
- Altered pressure natriuresis
- Deficient natriuretic hormone
- Renin and nephron heterogeneity (Laragh-Sealy Hypothesis)
- Reduced nephron number
-
Altered pressure natriuresis
- Normally: increased BP –> increased Na delivery to distal nephron –> increased Na excretion
- Na loss –> decreased BP back to normal
- If pressure natriuresis is “reset”
- Pt will regulate around a higher baseline BP or have decreased sensitivity to volume expansion
- –> higher pressures
- Normally: increased BP –> increased Na delivery to distal nephron –> increased Na excretion
-
Deficient natriuretic hormone
- Increase volume –> release natriuretic hormone –> inhibits Na-K ATPase –> decreased Na reabsorption
- Defect in this hormone –> prevent excretion of excess Na loads
-
Renin and nephron heterogeneity (Laragh-Sealy Hypothesis)
- Sub-population of ischemic nephrons chronically releases renin –> HTN
- Increase BP –> decrease renin
- Most pts w/ primary HTN have normal or high renin levels (70%) due to…
- Nephron heterogeneity (i.e., subgroup of nephrons that are ischemic and release excess renin)
- RAAS that doesn’t modulate properly
- Increased sympathetic drive
-
Reduced nephron number
- Congenital reduction in the # of glomeruli –> fewer nephron units to excrete excess Na loads –> HTN
Pathogenesis of HTN:
Cardiac output:
Role of SNS
- Baroreceptors
- Excess stress
- SNS net effect
- Reset baroreceptors
- Aortic arch, carotid sinus, & cardiopulmonary baroreceptors
- Regulate at higher set points of BP
- Excess stress –> increased SNS
- Intermittent stress –> Epi release –> increased BP
- BP remains elevated for some time afterwards
- Epi acts on pre-synaptic β2 receptor –> NE release
- Cardiac NE spillover
- Higher in HTN pts
- Correlates directly w/ Epi release
- HTN patients have faulty NE re-uptake
- Intermittent stress –> Epi release –> increased BP
- SNS net effect
- –> decreased RBF & GFR
- –> increased renal Na reabsorption
Pathogenesis of HTN:
Role of total peripheral resistance (TPR)
- TPR
- Primary lesion in HTN
- May be…
- Possible candidates
- Arterial stiffness
- Increase age –>
- Major determinant of CV risk
- Cell membrane alterations
- TPR
- Increased peripheral resistance maintains HTN
- Regulated by vascular endothelial cell & vascular smooth muscle cell
- Primary lesion in HTN
- May be structural remodeling of blood vessels in childhood
- Possible candidates
- RAAS
- Endothelin-1 – high plasma levels in HTN pts
- Transforming Growth Factor β1
- Insulin like growth factor
- Mechanical forces – hemodynamic shear
- Nitric oxide – whole body NO production is decreased in pts w/ essential HTN
- Arterial stiffness
- Increase age –> progressive increase in systolic BP
- Collagen deposition in the blood vessels
- Smooth muscle hypertrophy
- Altered elastin vascular media
- Age associated endothelial dysfunction
- Major determinant of CV risk: increasing pulse pressure
- Increase age –> progressive increase in systolic BP
- Cell membrane alterations
- IC Na is higher in cells from HTN pts
- Altered Na/H exchange
- Altered membrane composition
- Ca transport & binding – calcium content increased in the membranes of HTN pts
Pathogenesis of HTN:
Other factors
- Weight
- Framingham study
- Associated w/…
- Mineral metabolism
- Tobacco
- Caffeine
- Alcohol
- Moderate quantities
- Larger quantities
- Obesity
- Framingham study: gain 10lb –> increase systolic BP by 4.5 mmHg
- Associated w/…
- Increased CO
- Intravascular volume
- SNS activity
- Increased RAAS
- Diminished NO mediated vasodilation
- Hyperinsulinemia
- Mineral metabolism
- Decreased Ca intake + increased Ca excretion –> increased HTN
- Decreased dietary K &Mg –> increased BP
- Lead causes HTN
- Tobacco
- BP increases for 30 minutes following tobacco use
- Caffeine
- Increases BP
- Tolerance develops to pressor effect
- Alcohol
- Moderate quantities: may contribute to HTN
- Larger quantities: significant contributor
- 10% of HTN in men –> directly linked to ethanol
- BP decreases when heavy drinkers abstain
- HTN pts should drink < 2 standard drinks / day
- Standard drink = 12 oz beer, 5 oz wine, 1.5 oz hard liquor
Pathogenesis of HTN:
Secondary causes of HTN
- Presentation
- Renal parenchymal disease
- Renovascular HTN
- Presentation
- < 35yo with abrupt onset of HTN
- No family hx of HTN
- Fail empiric therapy.
- Renal parenchymal disease
- Decreased ability to excrete Na & water –> volume expansion & increased CO
- Autoregulation –> increae TPR –> decrease CO –> HTN
- Renovascular HTN
- Caused by > 80% renal artery stenosis
- 1% of unselected pts w/ HTN have this lesion
- Surgically correctable
- Arterial constriction –> decreased renal perfusion –> increased renin & AII –> increase BP
- Causes
- Atherosclerosis aortic aneurysm, emboli, and arteritis.
- Fibromuscular dysplasia: disease of the layers of the blood vessel (usually medial fibroplasia)
- Caused by > 80% renal artery stenosis
Pathogenesis of HTN:
Secondary causes of HTN
- Adrenal gland causes of HTN
- Pheochromocytoma
- Primary aldosteronism
- Cushing’s syndrome
- Miscellaneous Causes of secondary HTN
- Adrenal gland causes of HTN
- Pheochromocytoma
- Chromaffin cell tumors episodically increase BP
- Associated w/ tachycardia, sweating, flushing & tremor
- Primary aldosteronism
- Due to adrenal adenomas or adrenal hyperplasia
- Classic features: HTN, hypokalemia, excess urinary K losses, metabolic alkalosis, & hypernatremia
- Cushing’s syndrome
- Caused by excess cortisol
- Due to excess ACTH from the pituitary –> excess adrenal production of cortisol
- May be from excess unstimulated production of cortisol by the adrenal gland
- Pheochromocytoma
- Miscellaneous Causes of secondary HTN
- Coarctation of the Aorta
- Hypothyroidism and hyperthyroidism
- Hyperparathyroidism
- Sleep apnea
- Meds
- Erythropoietin
- Cyclosporine
- Tacrolimus (FK 506)
- Street Drugs
- Cocaine
- Bath salts
- Amphetamines
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Evaluation of HTN:
History
- Family hx
- Review of systems (ROS)
- Evaluate…
- Diet
- Meds
- Family hx
- High BP
- Early heart disease
- Cerebrovascular accidents (CVA)
- Peripheral vascular disease
- DM
- Lipid abnormalities.
- Review of systems (ROS)
- Emphasis on cardiac & neurologic complaints
- Previous hx of renal diseases, DM, or lipid abnormalities
- Previous HTN or anti-HTN therapy
- Evaluate…
- Weight hx
- Smoking
- Physical activity
- Diet
- Fat, alcohol, & Na intake
- Meds
- Drugs that increase BP
- Oral contraceptives
- Steroids
- Immunosuppresive drugs
- NSAIDs
- Decongestants
- Appetite suppressants
- Tricyclic antidepressants
- Monoamine oxidase inhibitors
- Street drugs
- Drugs that increase BP
Evaluation of HTN:
History
- Symptoms suggestive of secondary HTN (uncommon)
- When the pt considered to have HTN
- Symptoms suggestive of secondary HTN (uncommon)
- Episodic tachycardia, tremor, orthostatic HoTN, sweating, pallor & anxiety –> pheochromocytoma
- Severe HTN in a young pt w/ no family hx of HTN
- HTN poorly responsive to interventions
- Well-controlled HTN that becomes poorly controlled
- Sudden onset of HTN or presentation w/ accelerated or malignant HTN
- When the pt considered to have HTN
- Diagnosis not made on basis of single measurement
- Confirm elevation on > 2 subsequent visits over several weeks
- Unless BP is in severe or very severe range –> hospitalization or more frequent outpatient visits
- Severe HTN in presence of target organ damage (TOD)
- CHF, angina, stroke, or renal failure
- Indication for hospitalization
Evaluation of HTN:
Measuring & monitoring BP
- Measuring BP
- Role of 24 hour ambulatory BP monitoring
- Why
- When
- Advantages of self-measurement
- Measuring BP
- Pt seated w/ arm bared, supported, & at heart level
- No nicotine or caffeine within 30 minutes before measurement
- Measure after 10-15 minutes of rest
- Use appropriate cuff size
- Cuff bladder must cover >80% of arm circumference.
- First appearance of sound is the systolic pressure
- Disappearance of sound is true diastolic (Phase V)
- Muffling (Phase IV) is not true diastolic
-
> 2 measurements separated by 2 minutes should be averaged
- If values differ by > 5 mm Hg –> additional readings
- Initial exam should include BP in both arms
- Higher BP = true BP
- Role of 24 hour ambulatory BP monitoring
- BP measurements in the office may not reflect the pt’s usual BP
- When 24 hour ambulatory BP monitoring may be helpful
- BP elevated on multiple occasions in clinic setting but repeatedly normal out of hospital
- Aka “white coat” HTN
- Drug therapy appears to be ineffective
- Episodic HTN
- Evaluation of nighttime BP changes
- Excess anti-HTN effect (i.e., orthostatic HoTN)
- BP elevated on multiple occasions in clinic setting but repeatedly normal out of hospital
- Advantages of self-measurement
- Identifies “white-coat HTN”
- Assess response to meds
- Improves adherence to treatment
- Potentially reduces costs
- Usually provides lower readings than those recorded in clinic
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Evaluation of HTN:
Physical & lab exams
- Physical
- Labs
- Physical
- > 2 BP readings > 2 minutes apart w/ pt supine or seated & after standing for > 2 minutes
- Check opposite arm & use higher value
- Measure height & weight.
- Fundoscopic exam
- Examine neck for carotid bruits, enlarged thyroid, & venous distention
- Cardiac exam looking for tachycardia, laterally displaced PMI, precordial heave, clicks, murmurs, & S3 / S4 gallops
- Examine abdomen for bruits (anteriorly and posteriorly), enlarged kidneys, masses, & abdominal aortic pulsation
- Examine extremities for diminished pulses (coarctation or peripheral vascular disease [PVD]), bruits, or edema
- Neuro exam
- Labs
- Urinalysis for proteinuria
- Centrifuged urine sediment exam for acute renal disease
- CBC, glucose, electrolytes, BUN, Creatinine, uric acid, fasting lipid profile & EKG
- Urinalysis for proteinuria
Evaluation of HTN:
Optional tests & procedures
- Creatinine clearance
- Microalbuminuria
- 24-hour urinary protein
- Serum calcium
- Serum uric acid
- Fasting triglycerides
- LDL cholesterol
- Glycosolated hemoglobin
- Thyroid-stimulating hormone
- Plasma renin activity/ urinary sodium determination
- Limited echocardiography
- Ultrasonography
- Serum Aldosterone
Consequences of HTN
- Cardiac
- Cerebrovascular
- Peripheral vasculature
- Renal
- Retinopathy
- Grade 1
- Grade 2
- Grade 3
- Grade 4
- Grade 3 & 4
- Cardiac
- Clinical, electrocardiographic, or radiologic evidence of coronary artery disease
- EKG shows LVH
- LVH detected by echo is highly predictive of future cardiac events (MI, CHF)
- CHF and LV dysfunction frequently seen
- Direct correlation of incidence of coronary heart disease & systolic BP
- Cerebrovascular
- Transient ischemic attack (TIA)/CVA
- Direct correlation of BP elevations & incidence of strokes
- Anti-HTN therapy has the greatest impact.
- Peripheral vasculature
- Accelerated atherosclerosis of distal arteries –> diminished circulation to extremities –> ischemia w/ exertion and pain (claudication)
- Ischemia at rest –> ischemic ulcers of the toes, feet, lower legs, & fingers
- Renal
- Serum Creatinine > 1.5
- Clinical proteinuria (1+ or more on standard dipstick)
- Microalbuminuria
- Retinopathy
- Grade 1 - first crossing AV nicking
- Grade 2 - copper wire narrowing of retinal arterioles, second crossing AV nicking
- Grade 3 - silver wire narrowing of retinal arterioles Cotton wool exudates, hemorrhage
- Grade 4 - hemorrhage and exudates with papilledema
- Grade 3 & 4 - high association w/ progressive renal failure
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Pathophysiology of essential hypertensive renal disease
- 20-30yo: phase 1
- 30-40yo: phase 2
- 40-50yo: phase 3
- >50yo
- Phase 4
- Phase 5
- 20-30yo: phase 1
- Increase in Renal Vascular Resistance (RVR) due to…
- Functional disturbance of renal vasculature
- Over active vasoresponse to endogenous AII
- NE
- Increase in Renal Vascular Resistance (RVR) due to…
- 30-40yo: phase 2
- Further increase in RVR w/ both functional & structural disturbances in renal vasculature
- Decrease in renal perfusion
- Preservation of GFR (although glomeruli may be ischemic)
- Increase in FF
- Microalbuminuria
- 40-50yo: phase 3
- Further increase in RVR
- Structural disturbances involving renal vasculature & glomeruli (arteriolar nephrosclerosis)
- Decrease in perfusion disproportionately > decrease in filtration
- Sustained rise in FF
- Proteinuria
- >50yo
- Phase 4
- Critical decrease in renal mass
- Decrease in RVR (reduction in afferent arteriolar resistance)
- Increase in glomerular capillary hydraulic pressure
- Progressive decrease in GFR
- Nephrosclerosis
- Glomerulosclerosis
- Phase 5
- Chronic renal insufficiency progressing to ESRD
- Phase 4
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