Disorders of Blood Pressure Regulation

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: represents the average pressure in the arterial system during ventricular contraction and relaxation
Arterial Blood Pressure
Represents the pressure of the blood as it moves through the arterial system
Is determined by the cardiac output and the resistance that blood encounters as it moves through the peripheral vessels
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 that is stored in the aorta as its elastic fibers are stretched during systole
The resistance to the runoff of blood from the peripheral blood vessels

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
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
Factors Influencing Mean Arterial Blood Pressure
Physical
Blood volume and the elastic properties of the blood vessels
Physiologic factors
Cardiac output
Peripheral vascular resistance
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 group
Categories of Hypertension
Primary hypertension (essential hypertension)
The chronic elevation in blood pressure that occurs without evidence of other disease
Secondary hypertension
The elevation of blood pressure that results from some other disorder, such as kidney disease
Malignant hypertension
An accelerated form of hypertension

Risk Factors for Hypertension
Family history
Age-related changes in blood pressure
Race
Insulin Resistance and Metabolic Abnormalities
Circadian variations
Lifestyle factors

Lifestyle Factors Contributing to Hypertension
High salt intake
Obesity
Excess alcohol consumption
Dietary Intake of Potassium, Calcium, and Magnesium
Oral contraceptive drugs
Stress

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
Drugs Used in the Treatment of Hypertension
Diuretics
β-adrenergic–blocking drugs
Angiotensin-converting enzyme (ACE) inhibitors
Angiotensin II receptor blockers
The calcium channel–blocking drugs
Central α2-adrenergic agonists
α1-adrenergic receptor blockers
Vasodilators
Factors Affecting Treatment Strategies for Hypertension
The Person’s lifestyle
Demographics
Motivation for adhering to the drug regimen
Other disease conditions and therapies
Potential for side effects
Most Common Causes of Secondary Hypertension
Kidney disease (renovascular hypertension)
Adrenal cortical disorders
Pheochromocytoma
Coarctation of the aorta
Sleep apnea
Types of Hypertension in Pregnancy
Gestational hypertension
Chronic hypertension
Preeclampsia-eclampsia
Preeclampsia superimposed on chronic hypertension

Diagnosis and Treatment of Hypertension in Pregnancy
Early prenatal care
Refraining from alcohol and tobacco use
Salt restriction
Bed rest
Carefully chosen antihypertensive medications
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
Causes of Orthostatic Hypotension
Conditions that decrease vascular volume
Dehydration
Conditions that impair muscle pump function
Bed rest
Spinal cord injury
Causes of Orthostatic Hypotension (cont.)
Conditions that interfere with cardiovascular reflexes
Medications
Disorders of autonomic nervous system
Effects of aging on baroreflex function

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
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