Week 4 Flashcards

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1
Q

Cardiovascular Disease

A

A class of diseases affecting the cardiovascular system
- diseases of the heart
- diseases of blood vessels
- vascular diseases of the brain

It is the leading cause of birth defects and death in the world
More deaths in first year than any other condition
Symptoms, prognosis will vary with the defect

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2
Q

CVDs not directly resulting from atherosclerosis

A
  • congenital heart disease
  • rheumatic heart disease
  • cardiomyopathies
  • cardiac arrhythmias
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3
Q

Causes of CVDs

A

single gene defects:
- Chromosomal disorders
- Environmental teratogens
- Micronutrient and deficiencies (e.g. iodine and folate)

Maternal disease:
- syphilis, rubella
- diabetes mellitus
- tobacco, alcohol and illicit drug exposure

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4
Q

Rheumatic heart disease

A
  • Cause: Rheumatic fever
  • common in poor socioeconomic conditions
    • 15.6 million people
    • Poor access to healthcare, nutrition…
  • streptococcal infection of tonsils and pharynx
    • Affects heart, joints, CNS
    • Causes fibrosis of the heart valves
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5
Q

Chagas disease - American trypanosomiasis

A

• Parasitic infection
• 10 million people are infected worldwide
• Transmitted by “kissing bugs” (Triatomine)
• Live in cracks of poorly constructed homes
• Causes destruction of the heart muscle
• Some control achieved through vector control, screening
• Further control could be achieved by improving living conditions

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6
Q

CVDs caused by atherosclerosis

A
  • Ischaemic heart disease, coronary artery disease (leads to myocardial infarction, aka heart attack)
  • Cerebrovascular disease (e.g. stroke)
  • Diseases of the aorta and arteries
    • Hypertension
    • Peripheral vascular disease
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7
Q

Pathophysiology of Atherosclerosis

A

Atherosclerosis results in narrowing of blood vessels and is the major cause of heart attacks and strokes

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8
Q

Mechanism by which atherosclerosis causes heart attacks and strokes

A
  • Fibrous cap ruptures → lipid fragments, cellular debris released into vessel lumen
  • Thrombogenic agents → formation of thrombus
    (thrombus: accumulation of RBCs, platelets)
  • Large thrombus in;
    • coronary blood vessel → heart attack
    • cerebral blood vessel → stroke
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9
Q

Myocardial Infarction (heart attack)

A
  • Blood flow to the heart is cut off
    • Decrease in supply of oxygen and nutrients
    • Damage to heart
  • Symptom: Angina
    • Blood flow decreased → ischemia → heart pain
  • Mechanisms of damage Ischaemia
    • Waste not removed
    • Mitochondrial damage
    • Leaking of proteolytic enzymes
  • Ischaemia reperfusion injury
    (Oxygen restoration)
    • more free radicals, reactive oxygen species → damage
    • Calcium overloading → arrhythmias, apoptosis
    • Exaggerates inflammation
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10
Q

Stroke

A

Ischaemic stroke: blood supply to brain affected.
• Thrombus formation in atherosclerotic cerebral blood vessels
• Small vessel disease in brain (very small atherosclerotic plaques)
• Embolisms can block blood flow
• Blood clots can form in heart travel
to brain through blood vessels.
• Atherosclerotic plaques from elsewhere can travel to cerebral vessels

Haemorrhagic stroke: due to blood vessel rupture
• Aneurysm (swelling in vessel wall)
• Can be caused by uncontrolled high blood pressure
• Atherosclerosis can increase blood pressure

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11
Q

Sudden Cardiac Arrest/ Sudden Cardiac Death

A

Failure of heart to beat – no blood pumping
Causes:
- 60-72% - Coronary Heart Disease
- 10% are due to structural heart disease not from CHD
• Cardiomyopathy (disease of heart tissue)
• Myocarditis (inflammatory cardiomyopathy)
• Hypertensive heart disease
• Congestive heart failure (heart does not act as an effective pump)
- 5-10% are due to arrhythmias
• Not all arrhythmias will be rectified by defibrillation
- 15-20% - non-cardiac causes (e.g. trauma, aortic rupture, poison)

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12
Q

Cardiac arrhythmia

A
  • Heartbeat originates as an electrical impulse
  • Causes synchronised contraction of the ventricles of the heart
  • Abnormal electrical activity – cardiac arrhythmia
    Too fast, too slow, regular, irregular
  • Can lead to deterioration in the mechanical function of the heart
    Sudden death due to a cardiac arrhythmia may be the first sign of coronary artery disease
  • Atrial fibrillation is associated with, complicated by stroke and congestive heart failure
    • Can be treated with medication
  • Risk factors for arrhythmia: • Age
    • Hypertension
    • Diabetes
    • Thyroid overactivity
    • Cardiac valve abnormalities
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13
Q

What is nutrition?

A
  • Nutrition is the “building” blocks of biological molecules
    • protein → nitrogen → nucleic acids
  • What cannot be made endogenously - must be provided exogenously
    • Vitamins, essential amino acids
    • Deficiency in some nutrients can cause morbidity
  • The requirement for energy
    • Carbohydrates, fats and protein catabolism
    • Excess energy intake is a public health problem
  • Foods which lead to adverse outcomes
    • Macronutrient balance, energy balance
    • Hypervitaminosis, alcohol
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14
Q

Macronutrients

A

Consumed in largest quantities, provide energy

  • proteins
  • fats
  • carbohydrates
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15
Q

Micronutrients

A

Required in small quantities for normal physiological function

  • vitamins are organic compounds
    • required in small amounts
  • dietary trace minerals (e.g. Iron)
    • required in tiny amounts
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16
Q

Nutrient Reference Values

A
  • Amount of each nutrient which, on average, meets nutritional needs of most healthy people; and aid in the prevention of chronic disease
  • Reference values are specific for age and biological need (childhood, pregnancy, lactation)
  • e.g. RDI
17
Q

RDI

A

Recommended Daily Intake
- The average daily dietary intake level that is sufficient to meet the
nutrient requirements of nearly all (97-98%) healthy individuals in a sex and particular life stage group
- RDIs exceed the actual nutrient requirements of practically all healthy persons and are not synonymous with individual requirements.
- RDI = EAR +2 Standard Deviation (EAR)

18
Q

Australian Dietary Guidelines

A
  • Types and amounts of foods, food groups and dietary patterns to:
    • Promote health and wellbeing
    • Reduce the risk of diet-related conditions
    • Reduce the risk of chronic disease
  • Dictated, in part, by Nutrient Reference Values
19
Q

EAR

A

Estimated Average Requirement
- nutrient level required to meet the need of approximately half the health individuals in a sex and particular life stage group

20
Q

AI

A

Adequate Intake
- when an EAR cannot be determined
- AI is an estimate of the nutrient intake of group(s) of apparently healthy people
- an observed or experimentally determined approximation

21
Q

UL

A

Upper Level of Intake
- the highest average daily nutrient intake level likely to pose no adverse health effects to almost all individuals in the general population
- as intake increases above UL, the potential risk of adverse effects increases

22
Q

SDT

A

Suggested Dietary Target
- a daily average intake from food and beverages for certain nutrients that may help in prevention of chronic disease, at levels higher than the EAR or RDI
- average intake may be based on the mean or median depending on the nutrient and available data

23
Q

Macronutrient balance

A
  • Macronutrients contribute to energy intake
  • Need to satisfy both;
    • energy requirements
    • other nutritional requirements
24
Q

AMDR

A

Acceptable Macronutrient Distribution Range

“The AMDR is an estimate of the range of intake for each macronutrient for individuals (expressed as per cent contribution to energy), which would allow for an adequate intake of all the other nutrients whilst maximising general health outcome

25
Q

Evidence grading system assessing literature

A
  1. Evidence Base: Type of studies (case report, cohort, randomised control trial, metanalysis); Size of studies
  2. Consistency: Is the literature in agreement?
  3. Clinical impact: What impact does it have on morbidity – what do the studies show?
  4. Generalisability: Which population was this research performed on? Does it apply to Australia?
  5. Applicability: Should this be applied to the Australian Dietary Guideline?
26
Q

Challenges of Dietary Guidelines

A
  1. How can we do nutritional studies
  2. Can we suggest politically controversial things?
  3. Do people take the advice anyway?
27
Q

Challenges in nutrition: scientific evidence

A

• Ideal study would be randomised, controlled, double blind study…but this is not ethically possible
• Ethical considerations: Can’t prescribe some diets as “treatment”
• Too many other confounding factors affect which “treatment” different individuals receive
• Can’t blind participants
• We don’t eat just one food – what is the “treatment”?
• What is the appropriate population to study? Generalisable?
• We can do observational studies, usually involving large cohorts.
• Self reporting is unreliable
• No easy way to assess nutrient intake otherwise
• Can’t control for other factors

28
Q

Nutritional research

A

• Nutritional research improves health
• Folate supplementation prevents neural tube defects
Trans fat is not good for heart disease
• Increased sugar intake increases risk of diabetes, fatty liver disease

29
Q

Challenges in nutrition: Will people take the advice?

A
  • A 2004 study found that only a third of middle aged Australian women achieved HALF of the dietary guidelines.
  • Current dietary guidelines are not attained by most people
30
Q

Tobacco use is an avoidable risk factor

A
  • Contributes to to
    • myocardial infarction
    • stroke
    • sudden death
    • heart failure
    • aortic aneurism,
    • peripheral vascular disease
  • Aims:
    • Reduce smoking
    • Reduce second-hand smoke
31
Q

Physical inactivity and CVD

A
  • Insufficient physical activity is the fourth leading risk factor for mortality
  • 3.2 million deaths each year attributed to insufficient physical activity
  • 20-30% increased risk of all-cause mortality vs. those who engage in 30min of moderate activity.
  • Mechanism: Improves endothelial function
    • Enhances vasodilation, vasomotor function in blood vessels
    • Effect on CVD partially through intermediate risk factors.
    § Glycaemic control, improved BP, lipid profile, insulin sensitivity
32
Q

Alcohol and CVD

A

•14% of alcohol attributable deaths are due to CVD and diabetes mellitus
• Direct causal relationship between level, patterns of alcohol consumption and CVD
• Binge (episodic) drinking associated with increased risk of CVD
• Damage heart muscle - risk of stroke, cardiac arrhythmia.

33
Q

Risk factors that can be avoided

A
  • high blood pressure
  • smoking
  • type 2 diabetes
  • lack of exercise
  • obesity
  • hyperlipidaemia
  • high blood cholesterol
  • excessive alcohol consumption
34
Q

Shared causative factors

A
  • heart disease
  • stroke
  • cancer
  • diabetes
  • respiratory disease