PHTY208 Lecture Notes - Lecture 8: Pheochromocytoma, Cardiac Muscle, Constrictive Pericarditis
Disorders of blood pressure, heart failure and circulatory shock:
Lecture overview:
-Arterial blood pressure
-Hypertension
-Hypotension
-Heart failure
-Circulatory failure (shock)
Introduction:
-Adequate perfusion of body tissue depends on:
-Pumping ability of the heart
-Transport of blood through the vessels
-Sufficient blood to fill the circulatory system
-Tissues ability to extract and use oxygen and nutrients
-Blood pressure is one of the most variable but best regulated functions of the body
-HF and circulatory shock reflect the failure of the system
Concept 1: Arterial blood pressure:
Arterial blood pressure:
-reflects the rhythmic ejection of blood from he left ventricle into the aorta
-Systolic press: 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 press in the arterial system during ventricular contraction
and relaxation
Mechanisms of blood pressure regulation:
-Short term regulation: corrects temporary imbalances in blood pressure
-Neural mechanisms- ANS (medulla and pons)
-Baroreceptors
-Chemoreceptors
-Hormonal mechanisms
-RAAS
-ADH
-Epinephrine
-Long-term regulation: controls the daily, weekly, monthly, regulation of blood pressure
-Renal mechanism
Concept 2: Hypertension (essential (primary) hypertension)
Hypertension:
Normal:
-Systolic pressure less than 120mm Hg
-Diastolic pressure of less than 80mm Hg
Prehypertensive:
-Systolic pressures between 120 and 139mm Hg
-Diastolic pressures between 8- and 89mm Hg
Hypertension:
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-Systolic blood pressure is 140mm Hg or higher Diastolic blood pressure is 9-mm Hg or higher
For adults with diabetes mellitus, the goal is BP less than 140/80mm Hg
Categories of hypertension:
Primary hypertension (essentail hypetension):
-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
Classifications of essential hypertension:
-Systolic/diastolic hypertension
-Both he systolic and diastolic pressures are elevated
-Diastolic hypertension
-Diastolic pressure is selectively elevated
-Systolic hypertension
-Systolic pressure is selectively elevated
Risk factors for hypertension:
-Family history
-Age-related changes in blood pressure
-BP in newborn is - 50mm Hg systolic and - 40mm Hg diastolic
-BP in 10 day old is 78mm Hg systolic
-BP at end of adolescence is - 120mm Hg systolic
-Diastolic increases with age until - 60 then declines
-Race
-More prevalent in African Americans and Indigenous Australians
-Higher at earlier age
-More prone to renal damage
-Insulin resistance and metabolic abnormalities
-Strong link between insulin resistance, impaired glucose tolerance, type 2 diabetes,
hyperlipidemia, obesity and hypertension
-Circadian variations
-Blood pressure normally varies throughout the day/night
-Highest one early morning and decreases throughout the day
-Lifestyle factors
Lifestyle factors contributing to hypertension:
-High salt intake
-May elevate blood volume
-Increase sensitivity of cardiovascular or renal mechanisms to sympathetic nervous system
influences
-May exert effect through RAAS
-Obesity
-Fat distribution may be important, WHR commonly used, but waist circumference seems more
important
-Other hormones associated with obesity may also contribute to hypertension
-Excess alcohol consumption
-Regular consumption of 3 or more standard drinks increases risk
-Dietary intake of potassium, calcium, and magnesium
-Possible change in Na/K ration
-Direct natriuretic effect
-Suppression of RAAS
-Increase K+ causes a reduction of Na+
-Oral contraceptive drugs
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-Increase risk of hypertension possible volume expansion as pills causes Na+ retention
-BP usually returns to normal after cessation
-Stress
Clinical manifestations:
-Waking headache, sometimes with nausea and vomiting, caused by increase intracranial blood
pressure
-Epistaxis
-Bruits
-Blurred vision
-Confusion
-Fatigue
-Dizziness or unsteadiness in gait
-Nocturne
-Dependent oedema
Target organ damage:
-Heart
-Hypertrophy
-Angina or prior myocardial infarction
-Heart failure
-Brain
-Dementia and cognitive impairment stoke of transient ischemic attack
-Peripheral vascular- atherosclerosis
-Kidney- nephrosclerosis
-Retinal complications
Treatment of hypertension:
Lifestyle modification:
-Weight reduction- physical activity
-Dietary changes- salt, alcohol
-Decrease smoking (stop)
Drugs:
-Diuretics
-B-adrenergic-blocking drugs
-Angiotension-converting enzyme (ACE) inhibitors
-Angiotensin II receptor blockers
-Calcium-channel-blocking drugs
-Central a2-adrenergic agonists
-A1-adrenergic receptor blockers
-Vasodilators
Factors affecting treatment strategies:
-Lifestyle
-Demogaphics
-Motivation for adhering to the drug regimen
-Other disease conditions and therapies
-Potential for side effects
Secondary hypertension (other forms of hypertension):
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Document Summary
Disorders of blood pressure, heart failure and circulatory shock: Adequate perfusion of body tissue depends on: Suf cient blood to ll the circulatory system. Tissues ability to extract and use oxygen and nutrients. Blood pressure is one of the most variable but best regulated functions of the body. Hf and circulatory shock re ect the failure of the system. Re ects the rhythmic ejection of blood from he left ventricle into the aorta. Systolic press: pressure at the height of the pressure pulse. Pulse pressure: the difference between systolic and diastolic pressure. Mean arterial pressure: the average press in the arterial system during ventricular contraction and relaxation. Short term regulation: corrects temporary imbalances in blood pressure. Long-term regulation: controls the daily, weekly, monthly, regulation of blood pressure. Diastolic pressure of less than 80mm hg. Systolic pressures between 120 and 139mm hg. Diastolic pressures between 8- and 89mm hg.
