Hypertension Flashcards
What is the definition of BP?
Pressure inside blood vessels or heart chambers relative to atmospheric pressure (mm Hg).
Measure of the force being exerted on the walls of the ARTERIES as blood is pumped out of the heart.
What are the MAJOR factors that determine BP?
include AGE, SEX, BODY MASS INDEX, and DIET (mainly sodium intake).
(always increase BP b/c water follows Na+)
Blood Pressure =
Cardiac Output X Peripheral Vascular Resistance
Cardiac Output =
Heart Rate X Stroke Volume
What are the normal adult values for CO, HR & SV?
Cardiac Output = Heart Rate X Stroke Volume
4900 ml/min = 70 bts/min X 70 ml/bt
Peripheral (systemic) vascular resistance:
The “squeeze” of blood vessels outside heart resisting blood flow.
Cardiac output:
A measure of how much blood is pumped out of left ventricle.
Stroke volume:
Blood volume ejected with each heart beat
Arterial BP:
The pressure exerted on the artery walls. There are
two measures of blood pressure:
* Systolic BP
* Diastolic BP
Systolic BP:
The pressure in arteries during SYSTOLE (contraction)
Diastolic BP:
The pressure in arteries during DIASTOLE (rest/filling)
Systole:
HIGHEST pressure point in cardiac cycle when ventricles
are contracting.
Diastole:
LOWEST pressure point in cardiac cycle when ventricles
are filling with blood.
Normal BP:
<120 mmHg (systolic); <80 mmHg (diastolic)
Mean arterial pressure:
The average arterial pressure throughout cardiac cycle
Mean Arterial Pressure (MAP)
2/3 diastolic blood pressure (time spent in diastole)
+
1/3 systolic blood pressure (time spent in systole)
basically = 2/3 REST + 1/3 CONTRACTION
Preload:
- The tension in the heart muscle or chamber at the end of diastole before the contraction
- It depends on ventricular end diastolic volume (amount of blood at end of diastolic)
Afterload:
The arterial pressure against which the heart must eject its cardiac output
What is the Frank-Sterling law?
- The STRENGTH of CONTRACTION depends on the INITIAL LENGTH of cardiac muscle fibers before contraction.
- The MORE STRETCHED the muscle BEFORE contraction the STRONGER the contraction.
- The INITIAL LENGTH of the heart muscle before contraction depends on the END DIASTOLE VOLUME.
↑ strength of contraction =
↑ stroke volume
What does the Frank-Sterling curve result in?
↑ end diastolic volume –>
↑ stretch in cardiac
muscle –>
↑ stroke volume
- end diastolic volume = ~140 ml
- stroke volume = ~70 ml
End diastolic volume =
~140 ml
Stroke volume =
~70 ml
What is the Regulation of blood pressure?
- Central Nervous System
* SNS: ↑ heart rate ↑ stroke volume (b/c of ↑ in contractility)
* PSNS:↓ heart rate - Kidney
* renin
* angiotensin II - Hormones
* aldosterone
* cortisol
* epinephrine
* ADH
What helps with the regulation of BP within this:
Blood Pressure = Cardiac Output X Peripheral Resistance
Blood Pressure = Cardiac Output X Peripheral Resistance
CARDIAC OUTPUT:
- Blood Volume: sodium, mineralocorticoids, atriopeptin
Cardiac Factors:
- heart rate, contractility
PERIPHERAL RESISTANCE:
- Humoral Factors:
– Constrictors: angiotension II, catecholamines, thromboxane, leukotrienes, endothelin
– Dilators: prostaglandins, kinins, nitric oxide
- Neural Factors:
– Constrictors: a-adrenergic
– Dilators: B-adrenergic
What is the role of kidney in regulation of BP?
Renin-Angiotensin System
- basically, angiotension II causes a ↑ vasoconstriction (which ↑BP & ↑CO) & aldosterone secretion (which ↑mineralocorticoids & ↑Na+ reabsorption which ↑CO & ↑BP & ↑vasoconstriction)
Glomerular filtration rate
- ↓BP
- ↓ glomerular filtration
- ↑ reabsorption of Na+ by proximal tubules
- ↑BV
Natriuretic factors
- volume expansion
- release of natriuretic factors (atrial & ventricular myocardium)
- ↓Na+ reabsorption in distal tubes
- ↑Na+ excretion
- diuresis (more water excreted - get rid of Na+ & water, therefore BP goes back to normal)
What is the role of neural system in regulation of BP?
Extrinsic Reflexes:
outside circulatory system;
Intrinsic Reflexes:
within circulatory system; baroreceptor/chemoreceptor
Higher Center Reflexes:
mood, emotion
(more on slide 15)
What are the role of other hormones in regulation of BP?
- NATRIURETIC HORMONE
- inhibits Na+/K+-ATPase
- vasodilation
- INSULIN
HYPERINSULINEMIA (e.g. insulin resistance state): - ↑ renal Na+ retention
- acts as growth hormone (vascular smooth muscle and
endothelial hypertrophy) - VASOCONSTRICTION (↑ Ca2+ in vascular smooth muscles)
- ↑sympathetic nerve activity
What is the role of blood vessel related factors in regulation of BP?
Endothelial layer of blood vessels releases factors that promote vasodilation or vasoconstriction
angiotensin II vasopressin endothelin –> vasoconstriction (↑ vascular resistance)
prostacyclin nitric oxide bradykinin –> vasodilation
(↓ vascular resistance)
Angiotensin II vasopressin endothelin –>
vasoCONSTRICTION (↑ vascular resistance)
Prostacyclin nitric oxide bradykinin –>
vasoDILATION
(↓ vascular resistance)
What is the effects of Sodium (Na+) electrolyte imbalance on BP?
Elevated Na+ intake (e.g. diet) is associated with hypertension (due to water retention)
What is the effects of Calcium (Ca2+) electrolyte imbalance on BP?
Elevation in intracellular Ca2+ level can result in increased peripheral resistance (BP = CO X TPR)
hat is the effects of Potasium (K+) electrolyte imbalance on BP?
Low K+ may increase peripheral vascular resistance (BP = CO X TPR)
What can be used for the measurement of BP?
- BP cuff
- bulb
- sphygmomanometer
- stethoscope
- Digital BP monitor and cuff
What are the 6 steps for the measurement of BP?
step 1.
place the cuff around the arm
step 2.
make sure you have found the artery (& feel pulse)
step 3.
place the stethoscope on the artery
step 4.
pump up the cuff until pressure in the cuff is elevated above systolic pressure (180-200 mm Hg)
- don’t go any higher & for not that long
step 5.
release pressure slowly until first heart sounds are heard (systolic pressure)
step 6.
continue to release pressure until no sound is heard (diastolic)
1st sound =
systolic pressure
No sound =
diastolic pressure
What is the classification of hypertension?
- Patients must have at least TWO BP readings (two different visits) for diagnosis of hypertension
- use same hand (b/c hands can be slightly diff.) & do at same ish time each time & use same device (sethoscope each time for ex)
- Hypertension is usually ASYMPTOMATIC “silent killer”
Low risk of HTN category =
Systolic/Diastolic: 120 / 80
Medium risk of HTN category =
Systolic/Diastolic: 121-134 / 80-84
High risk of HTN category =
135+ /85+
HTN affects _____ people worldwide
> 800 million
About ___% of people in the ____ ______ have
hypertension
25%
general population
_______ Canadians have hypertension (1:5)
> 5 million
Only a ___ _____ of hypertensive patients have been ____ and controlled
small portion
treated
reasons: asymptomatic (don’t want to take drugs if they don’t feel any symptoms)
_____ BP is ____ _____ than diastolic BP as a determinant of cardiovascular risk
systolic
more important
______ and vulnerability to complications of hypertension ______ with ____
prevalence
increase
age
What are the risk factors for developing hypertension?
- age
- obesity (BMI ≥ 30 kg/m2)
- stress (esp. chronic stress)
- hyperinsulinemia (diabetes)
- genetic factors (family history of hypertension)
- race (e.g. African Americans vs. Caucasians)
- dyslipidemia (↑ LDL, ↓HDL, ↑ triglycerides)
- life style factors:
- smoking, lack of exercise
- ↑salt intake, ↑fat diet, ↑alcohol intake
Kidney factors/problems:
* Microalbuminuria
* hyperuricemia
Describe relationship b/t HTN & atherosclerosis
HTN —> Atherosclerosis (b/c of damage to BV wall)
Atherosclerosis —> HTN (b/c narrows lumen of BV’s)
What are the different types of hypertension?
- Primary or essential hypertension
- Secondary hypertension
- Accelerated or malignant hypertension
- Primary or essential hypertension:
- It is also called “BENIGN HYPERTENSION”
- The mechanism(s) of high BP is not known (IDIOPATHIC)
- Includes 90-95% of patients with high BP
- Generally does NOT cause short-term problems
- Patients will have a normal life without any symptoms if blood pressure is controlled
- Secondary hypertension:
- Caused by an IDENTIFIABLE underlying medical problem
- Includes 5-10% of people with high BP
- The important underlying mechanisms are:
- primary renal disease
- hormonal disorders
- drugs
- If the problem is corrected, BP returns to normal
What is Primary renal disease?
- Caused by narrowing of the renal artery due to surgery, atherosclerosis, etc.
- kidney recognizes it as ↓BP by mistake, which leads to narrowing of renal artery
- Hypertension results from increased activation of renin-angiotensin-aldosterone pathway.
What is Hyperaldosteronism?
- Caused by overproduction of mineralocorticoids by the adrenal cortex.
- Elevated ALDOSTERONE to renin activity ratio.
- Leads to increased Na+/water resorption and K+
excretion in the kidney. - Primary hyperaldosteronism can be diagnosed by measuring blood levels of aldosterone and renin.
What is Cushing’s disease?
- Cushing’s disease is caused by:
- overproduction of CORTISOL by adrenal cortex
- high therapeutic doses of corticosteroids
- Characteristic: redistribution of fat in the body (moon face, buffalo hump on neck)
- Diagnosis: measurement of cortisol (blood, 24 h urine)
What is Pheochromocytoma?
- Caused by overproduction of ADRENALINE (stress hormone) from adrenal medulla
- Leads to very high blood pressure that is life-threatening
- Diagnosis: measurement of adrenaline in blood and 24 h urine and imaging (X-ray, CT-Scan, MRI)
What are the drugs related causes of hypertension?
- glucocorticoids (corticosteroids)
- esp. ↑ doses, their BP can be affected
- mineralocorticoids (fludrocortisone)
- alpha-agonists (decongestants, ergots, midodrine)
- beta-agonists (e.g. salbutamol)
- erythropoeitics (e.g. erythropoeitin)
- calcineurin inhibitors (cyclosporin, tacrolimus)
- NSAIDs
- cocaine, anabolic steroids, licorice
- oral contraceptives (estrogen)
- Accelerated or malignant hypertension:
- About 5% of hypertensive patients show a RAPIDLY rising BP; if untreated, leads to death in 1-2 years
- Clinical syndrome is characterized by SEVERE HYPERTENSION (systolic >200, diastolic >120 mmHg, renal failure, retinal hemorrhages)
- emergency case
- It may develop in previously normotensive people but often is superimposed on pre-existing hypertension (primary or secondary)
(malignant b/c rapidly ↑ in BP (dangerously)
What are complications of chronic hypertension?
Macrovascular atherosclerosis:
* coronary artery disease (angina, MI, SCD)
Myocardial hypertrophy:
* CHF (diastolic dysfunction)
* Cor pulmonale (or right heart failure)
Renal vascular disease:
* renal artery stenosis
* acute & chronic renal failure & proteinurea
Peripheral arterial disease:
* carotid stenosis (stroke)
* limb ischemia
Microvascular atherosclerosis:
* retinopathy (may lead to blindness)
* ischemic stroke
* erectile dysfunction (esp. in young ppl)
* cerebral microaneurysm (hemorrhagic stroke)
- become weaker & rupture –> bleeding in brain (can be irreversible)
Hypertensive encephalopathy (brain damage)
Hypertension is a MAJOR RISK FACTOR for _________, _____ ______ (e.g. CAD) and _________ accidents (stroke).
atherosclerosis
heart disease
cerebrovascular
Controlling BP _____ the ______ and _____ rates from ischemic heart disease, heart failure, and stroke.
reduces
incidence
death
(TIME IS IMP.)
Main target organs affected by chronic hypertension are ____, ____, ____, ____.
eyes
heart
kidney
brain
4 MAIN ORGANS AFFECTED
What are some complications of chronic hypertension?
- Hypertensive heart
- Retinopathy
- Cerebrovascular disease (hemorrhage in brain)
- Nephrosclerosis
What are the clinical tests for diagnosis of causes on hypertension?
- urine analysis (esp. 24 hours)
- blood biochemistry (Na+, K+, etc)
- fasting glucose
- cholesterol, HDL, LDL
- complete blood count (CBC) (easy & cheap)
- standard 12-lead ECG
- imaging (CT scan / MRI)
What are non-pharmacological strategies for treatment of hypertension?
Life style modifications
- weight loss (normal BMI: 18.5-24.9)
- physical activity (regular exercise)
- dietary sodium restriction
- moderation of alcohol consumption
What are pharmacological therapies for hypertension?
Classes of anti-hypertensive drugs
* diuretics
* beta-blockers
* angiotensin converting enzyme inhibitors (ACEIs)
* angiotensin II receptor blockers (ARBs)
* aldosterone antagonists
* calcium channel blockers (CCBs) (if block those channels you can ↓BP)
* alpha-1 adrenergic antagonists
**BP threshold for antihypertensive therapy is ______ in patients with high risk of cardiovascular disease and/or diabetes.
LOWER
