Download Systolic hypertension

Chapter 23
Disorders of Blood Pressure
Regulation
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Arterial Blood Pressure (Definitions)
• Systolic pressure: pressure at the height of the
pressure pulse
• Diastolic pressure: the lowest pressure
• Pulse pressure: the difference between systolic and
diastolic pressure
• Mean arterial pressure: the average pressure in the
arterial system during ventricular contraction and
relaxation
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Arterial Blood Pressure
• Represents the pressure of the blood as it moves through
the arterial system
• Cardiac output = HR x SV
• Vascular resistance (VR)
• Mean arterial pressure = CO x VR
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Mechanisms of Blood Pressure Regulation
• Short-term regulation: corrects temporary imbalances
in blood pressure
– Neural mechanisms
– Humoral mechanisms
• Long-term regulation: controls the daily, weekly, and
monthly regulation of blood pressure
– Renal mechanism
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Factors Determining Systolic and Diastolic
Blood Pressure
• Systolic pressure
– The characteristics of the stroke volume being ejected
from the heart
– The ability of the aorta to stretch and accommodate the
stroke volume
• Diastolic pressure
– The energy stored in the aorta as its elastic fibers are
stretched during systole
– The resistance to the runoff of blood from the peripheral
blood vessels
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Kortokoff Sounds
• Phase I: marked by the first tapping sound, which
gradually increase in intensity
• Phase II: period in which a murmur or swishing sound is
heard
• Phase III: period during which sounds are crisper and
greater in intensity
• Phase IV: period marked by distinct abrupt muffling or
by a soft blowing sound
• Phase V: point at which sounds disappear
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Factors Influencing Mean Arterial Blood
Pressure
• Physical
– Blood volume and the elastic properties of the blood
vessels
• Physiologic factors
– Cardiac output
– Peripheral vascular resistance
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Question
• Which of the following does not directly affect arterial
blood pressure?
a. Heart rate
b. Vascular resistance
c. Venous constriction
d. Blood volume
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Answer
a. Heart rate
b. Vascular resistance
c. Venous constriction: Venous constriction will not affect
arterial pressure, but the other factors will have
immediate effects.
d. Blood volume
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Joint National Committee on Detection,
Evaluation, and Treatment of Hypertension
• Systolic pressure less than 120 mm Hg and a diastolic
pressure of less than 80 mm Hg are normal.
• Systolic pressures between 120 and 139 mm Hg and
diastolic pressures between 80 and 89 mm Hg are
considered prehypertensive.
• A diagnosis of hypertension is made if the systolic blood
pressure is 140 mm Hg or higher and the diastolic blood
pressure is 90 mm Hg or higher.
• For adults with diabetes mellitus, the goal is BP less than
130/80 mm Hg
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Factors Affecting Hypertension
• Age
– More common in younger men than younger women
– More common in the elderly
• Race
– More common in blacks than whites
• Socioeconomic group
– More common in lower socioeconomic groups
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Categories of Hypertension
• Primary hypertension (essential hypertension)
– Chronic elevation in blood pressure that occurs without
evidence of other disease
• Secondary hypertension
– Elevation of blood pressure that results from some other
disorder, such as kidney disease
• Malignant hypertension
– An accelerated form of hypertension
• Systolic hypertension
– Systolic pressure of 140 mm Hg or greater and a diastolic
pressure of less than 90 mm Hg
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Classifications of Essential Hypertension
• Systolic/diastolic hypertension
– Both the systolic and diastolic pressures are
elevated.
• Diastolic hypertension
– The diastolic pressure is selectively elevated.
• Systolic hypertension
– The systolic pressure is selectively elevated.
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Risk Factors for Hypertension
• Family history
• Age-related changes in blood pressure
• Race
• Insulin resistance and metabolic abnormalities
• Circadian variations
• Lifestyle factors
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Lifestyle Factors Contributing to
Hypertension
• High salt intake
• Obesity
• Excess alcohol consumption
• Dietary intake of potassium, calcium, and magnesium
• Oral contraceptive drugs
• Stress
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Target Organ Damage
• Heart
– Hypertrophy
• Brain
– Dementia and cognitive impairment
• Peripheral vascular
–
Atherosclerosis
• Kidney
– Nephrosclerosis
• Retinal complications
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Drugs Used in the Treatment of
Hypertension
• Diuretics
• β-adrenergic–blocking drugs
• Angiotensin-converting enzyme (ACE) inhibitors
• Angiotensin II receptor blockers
• Calcium-channel–blocking drugs
• Central α2-adrenergic agonists
• α1-adrenergic receptor blockers
• Vasodilators
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Factors Affecting Treatment Strategies for
Hypertension
• Lifestyle
• Demographics
• Motivation for adhering to the drug regimen
• Other disease conditions and therapies
• Potential for side effects
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Question
• Renal failure results in Na+ and water retention. This
results in hypertension. How would you classify this
type of hypertension?
a. Primary hypertension
b. Secondary hypertension
c. Malignant hypertension
d. Systolic hypertension
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Answer
a. Primary hypertension
b. Secondary hypertension: Secondary hypertension
accompanies an underlying disease.
c. Malignant hypertension
d. Systolic hypertension
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Most Common Causes of Secondary
Hypertension
• Kidney disease (renovascular hypertension)
• Adrenal cortical disorders
• Pheochromocytoma
• Coarctation of the aorta
• Sleep apnea
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Types of Hypertension in Pregnancy
• Gestational hypertension
• Chronic hypertension
• Preeclampsia/eclampsia
• Preeclampsia superimposed on chronic hypertension
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Diagnosis and Treatment of Hypertension
in Pregnancy
• Early prenatal care
• Refraining from alcohol and tobacco use
• Salt restriction
• Bed rest
• Carefully chosen antihypertensive medications
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High Blood Pressure in Children and
Adolescents
• Blood pressure norms for children are based on age, height,
and gender-specific percentiles.
• Secondary hypertension is the most common form of high
blood pressure in infants and children.
– Kidney abnormalities
– Coarctation of the aorta
– Pheochromocytoma and adrenal cortical disorders
• In infants, hypertension is associated most commonly with
high umbilical catheterization and renal artery obstruction
caused by thrombosis.
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Orthostatic Hypotension
• Definition
– An abnormal decrease in blood pressure on
assumption of the upright position
• Causes
– Decrease in venous return to the heart due to
pooling of blood in lower part of body
– Inadequate circulatory response to decreased cardiac
output and a decrease in blood pressure
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Causes of Orthostatic Hypotension
• Conditions that decrease vascular volume
– Dehydration
• Conditions that impair muscle pump function
– Bed rest
– Spinal cord injury
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Causes of Orthostatic Hypotension (cont.)
• Conditions that interfere with cardiovascular
reflexes
– Medications
– Disorders of autonomic nervous system
– Effects of aging on baroreflex function
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Common Causes of Orthostatic
Hypotension Related to Hypovolemia
• Excessive use of diuretics
• Excessive diaphoresis
• Loss of gastrointestinal fluids through vomiting and
diarrhea
• Loss of fluid volume associated with prolonged bed rest
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Complaints Associated With Orthostatic
Intolerance
• Dizziness
• Visual changes
• Head and neck discomfort
• Poor concentration while standing
• Palpitations
• Tremor, anxiety
• Presyncope, and in some cases syncope
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Question
• Increased vascular compliance may contribute to which
condition?
a. Systolic hypertension
b. Orthostatic hypotension
c. Orthostatic hypertension
d. Diastolic hypertension
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Answer
a. Systolic hypertension
b. Orthostatic hypotension: Orthostatic hypertension is the
result of lower pressures, and increased compliance
would decrease the vascular resistance and result in
lower pressures.
c. Orthostatic hypertension
d. Diastolic hypertension
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