Week 4 Flashcards
Cardiovascular Disease
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
CVDs not directly resulting from atherosclerosis
- congenital heart disease
- rheumatic heart disease
- cardiomyopathies
- cardiac arrhythmias
Causes of CVDs
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
Rheumatic heart disease
- 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
Chagas disease - American trypanosomiasis
• 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
CVDs caused by atherosclerosis
- 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
Pathophysiology of Atherosclerosis
Atherosclerosis results in narrowing of blood vessels and is the major cause of heart attacks and strokes
Mechanism by which atherosclerosis causes heart attacks and strokes
- 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
Myocardial Infarction (heart attack)
- 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
Stroke
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
Sudden Cardiac Arrest/ Sudden Cardiac Death
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)
Cardiac arrhythmia
- 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
What is nutrition?
- 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
Macronutrients
Consumed in largest quantities, provide energy
- proteins
- fats
- carbohydrates
Micronutrients
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