Patho Hypo Hypertension

1. Alterations in Blood Pressure

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ArterialBlood
Pressure
Pressure differences
between the left and right
sides of the heart that
produce systemic
movement of blood
Arterial blood pressure is
produced by the force of
left ventricular
contraction overcoming
the resistance of the aorta
to open the aortic valve

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Arterial
Blood
Pressure
(Cont.)
Determinants of Systemic Blood Pressure
 Cardiac output (CO) and the resistance to
the ejection of blood from the heart
 CO = SV (stroke volume) x HR (heart rate)
 End-diastolic volume is the preload
 Amount of blood returned to the heart
 Systemic vascular resistance (SVR,
afterload) is determined by the radius of
arteries and degree of vessel compliance
 BP=CO x SVR

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Arterial BloodPressure(Cont.)
Systemic Arterial Blood Pressure

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ArterialBlood
Pressure(Cont.)
Measurement of Blood Pressure
 Components of blood pressure
measurement
 Systolic blood pressure—peak pressure
during cardiac systole
 Diastolic blood pressure—lowest pressure
during cardiac diastole
 SV is the primary factor influencing systolic
pressure
 SVR is the major determinant of diastolic
pressure
 Pulse pressure = Systolic - diastolic

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ArterialBlood
Pressure(Cont.)
Measurement of Blood Pressure
 Components of blood pressure
measurement
 Mean arterial pressure (MAP) is the
calculated average pressure within the
circulatory system throughout the
cardiac cycle
 MAP = (2 x diastolic pressure) +
systolic pressure
3

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ArterialBlood
Pressure(Cont.)
Direct Measurement of Blood Pressure
 Requires intraarterial catheter and
specialized equipment to transduce
arterial fluid pulsations into electrical
signals (waveforms)
 Catheter commonly placed in radial
artery
 Most accurate method of measuring
blood pressure

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ArterialBlood
Pressure(Cont.)
Indirect Measurement of Blood Pressure
Commonly measured via the
brachial artery using a
stethoscope and
sphygmomanometer or
automated oscillometric
system
Requires careful technique
to ensure accuracy
Auscultation of Korotkoff
sounds
 Systolic pressure: onset of Korotkoff sounds
 Diastolic pressure: disappearance of
Korotkoff sounds
White coat effect
Elderly: auscultatory gap

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Mechanismsof
Blood Pressure
Regulation
Short-Term Regulation of Systemic Blood
Pressure
 Changes in BP are mediated through
activation of the sympathetic nervous
system
 Results in release of neurotransmitters
epinephrine and norepinephrine
 Parasympathetic nervous system:
slows heart

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Mechanismsof
Blood Pressure
Regulation
(Cont.)
Short-Term Regulation of Systemic Blood
Pressure
 Vasomotor center directly
activated by various stimuli or
indirectly via baroreceptors
which monitor MAP variations
 Activates α1 receptors in smooth
muscle of arterioles, causing
vasoconstriction ( SVR)
 Activates β1 receptors of the heart
( heart rate)
 Chemoreceptors stimulate the
medullary vasomotor center to
increase SNS activity
 Located in carotid and aortic
arterials
 Activated only when BP
extremely low

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Mechanismsof
Blood Pressure
Regulation
(Cont.)
Long-Term Regulation of Systemic Blood
Pressure
 Regulated by neural, hormonal, renal
 Connected to fluid volume
 Increase in extracellular fluid volume =
increased CO and SVR = elevated BP
 Causes kidneys to excrete excess sodium
and fluid
 Increased serum sodium level =
increased osmolality = increased ADH
secretion
 Causes kidneys to reabsorb water

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Mechanismsof
Blood Pressure
Regulation
(Cont.)
Long-Term Regulation of Systemic Blood
Pressure
 Renin–angiotensin–aldosterone system
(RAAS) important regulator of BP
 Juxtaglomerular cells when stimulated by low
arterial pressure release renin activates
angiotensinogen to angiotensin I
 Angiotensin I when in contact with ACE
activates angiotensin II, a potent
vasoconstrictor and stimulates release of
aldosterone
 Aldosterone, a hormone, causes reabsorption of
sodium and water passively follows

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RAAS
SYSTEM

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Mechanismsof
Blood Pressure
Regulation
(Cont.)
Long-Term Regulation of Systemic Blood
Pressure
 Angiotensin II produces an increase in
SVR
 Atrial natriuretic peptides cause
kidneys to increase sodium and water
excretion by increasing the glomerular
filtration rate
 Endothelin-1: important in BP control

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Mechanisms
of Blood
Pressure
Regulation
(Cont.)
Normal Fluctuations in Systemic Blood
Pressure
 Suprachiasmatic nuclei (body’s
internal clock) in the brain govern daily
variations in bodily functions
 Rises before awaking (morning surge)
 Highest in the middle of the morning
 Lowest at night (nocturnal dip)
 Neural, hormonal regulation, external
environmental factors influence BP
 Lifestyle, cognitive activity and
emotional state can affect BP

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Hypertension
 Most common primary diagnosis in the
United States
 Increases morbidity and mortality
associated with heart disease, kidney
disease, peripheral vascular disease,
and stroke
 Responsible for an annual worldwide
death rate of 7 million

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Hypertension
(Cont.)
Definition and Classification
 Determined by the Joint National
Committee on Prevention, Detection,
Evaluation, and Treatment of High
Blood Pressure
 Pre-hypertension is a range of
pressures between normal and stage 1
hypertension in an effort to initiate
interventions early enough to prevent
or deter progression of the disease
process

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Hypertension(Cont.)
Adult Blood Pressure

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Hypertension
(Cont.)
Primary Hypertension
 Also called essential hypertension
 Idiopathic disorder
 Most common form of hypertension
 Rare prior to the age of 10
 Systolic BP: major risk factor for cardiovascular
disease

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Hypertension
(Cont.)
Primary Hypertension
 Subtypes
 Isolated systolic hypertension: systolic BP is ≥140
mm Hg while diastolic pressure remains <90 mm
Hg
 Isolated diastolic hypertension: diastolic pressure
is ≥90 mm Hg with a systolic pressure of <140 mm
Hg
 Combined systolic and diastolic hypertension: both
systolic and diastolic exceed prehypertension levels

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Hypertension
(Cont.)
Primary Hypertension
 Risk factors
 Nonmodifiable
 Family history
 Age
 Ethnicity/Genetics
 Modifiable
 Dietary factors
 Sedentary lifestyle
 Obesity/weight gain
 Metabolic syndrome
 Elevated blood glucose levels/diabetes
 Elevated total cholesterol
 Alcohol and smoking

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Hypertension
(Cont.)
Primary Hypertension
 Risk factors
 Childhood and adolescent (intrauterine)
 Maternal smoking
 Pregnancy induced hypertension
 Dietary habits
 Low birth rate followed by rapid
growth in both height and weight
 Lower socioeconomic level of mother
 Inadequate intake of calcium by
pregnant mother
 Breastfeeding seems to reduce the
risk

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Hypertension
(Cont.)
Primary Hypertension
 Sometimes called the “silent killer” as damage
has already occurred to organs before diagnosis
is made
 Outcomes
 End-organ damage
 Renal failure, stroke, heart disease
 Damage to arterial system and acceleration of
atherosclerosis lead to cardiovascular disease
 Increased myocardial work results in heart failure
 Glomerular damage results in kidney failure
 Affects microcirculation of the eyes
 Increased pressure in cerebral vasculature can result
in hemorrhage

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Hypertension
(Cont.)
Primary Hypertension
 Treatment
 Lifestyle modifications are first and most
important prevention and treatment
strategy
 Weight loss
 Exercise
 DASH diet
 Alcohol moderation
 Decreased sodium intake
 Drug therapy for hypertension affects
heart rate, SVR, and/or stroke volume

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Hypertension
(Cont.)
Lifestyle Modifications

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Hypertension
(Cont.)
Drug Classification
with Variable Affected

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Hypertension
(Cont.)
Secondary Hypertension
 Hypertension attributed to a specific
identifiable pathology or condition
 Most common form in infants and preschool
children
 Most common cause for childhood secondary
hypertension: renal disease and coarctation
of the aorta
 Other causes for children: obstructive sleep
apnea

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Hypertension
(Cont.)
Secondary Hypertension
 Adult secondary hypertension may be
related to:
 Renal artery stenosis
 Pheochromocytoma
 Pregnancy
 Obesity/obstructive sleep apnea
 Hyperaldosteronism: most common
cause

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Hypertension
(Cont.)
Hypertensive Emergencies and Urgency
 Called hypertensive crisis or malignant
hypertension (old term)
 Hypertensive emergency: sudden increase in
either or both systolic or diastolic blood
pressure with evidence of end-organ damage
 Rapid but controlled reduction of blood pressure
using parenteral antihypertensive agents under
close monitoring (typically in ICU setting)
 Hypertensive urgency: similar blood pressure
elevation without evidence of end-organ
damage
 Oral medications to bring blood pressure under
control over 24-48 hours

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Low Blood
Pressure
Orthostatic (Postural)
Hypotension
An extreme response to the
change from supine to
upright position; activation
of the short-term control
mechanisms is slow or
inadequate
Causes a decrease in
systolic blood pressure (>20
mm Hg or >10 mm Hg
within 3 minutes) when
moving to an upright
position

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LowBloodPressure (Cont.)
Orthostatic (Postural) Hypotension
 Excessive increase in heart rate (by 20-30 beats/minute) may also be
diagnostic
 Results in dizziness, blurred vision, confusion, and possible syncope
 Associated with cardiovascular disease and is a risk factor for stroke,
cognitive impairment, and death

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LowBloodPressure (Cont.)
Orthostatic (Postural) Hypotension
 May be a result of:
 Problem with vasomotor or baroreceptor
response
 Adverse effect of drug therapy
 Arterial stiffness
 Volume depletion
 Secondary disease process
 Vasovagal reaction
 Cardiac dysrhythmias

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Low Blood
Pressure
(Cont.)
Orthostatic (Postural) Hypotension
 Treatment
 Review medication history
 Slow positional changes
 Avoid hot environments
 Avoid large or carbohydrate-heavy meals
 When symptoms begin, squatting/bending
forward or crossing legs may reduce effects
 Elastic compression stockings, abdominal
binders, elevate head of bed
 Increase salt and fluid intake if not
contraindicated