Cardiovascular Disease and Ageing Flashcards
Where is most of the stroke volume stored and why?
Venous reservoir
Veins more compliant than arteries
How does CV disease incidence change with age?
Exponentially increases
What are the 2 types of age-related exposures?
Unavoidable - passage of time (ageing)
Avoidable - risk factors that accumulate over time
What do age-related exposures interact with and how do they determine outcomes?
Interact with genetic predisposition
Both contribute to reparative and deteriorative processes
Balance between reparative and deteriorative processes determines outcomes
What is the main evidence against the idea that coronary heart disease (CHD) is caused by avoidable exposures accumulating over time and not ageing itself?
Decreased CHD incidence since 1970s
At same time proportion of old people in population increased
What can most of the decrease in CHD incidence in Australia be explained by and what does this suggest?
Decreased lifestyle risk factor exposure - decreased smoking, controlled blood pressure, decreased cholesterol
Suggests due to lifestyle changes and improved treatments
How is the incidence of heart failure changing, why is this notable, and what does it suggest?
Increasing
Exception to overall decreasing CVD rates
Could be disease of ageing
Name the 3 factors that cause effects often attributed to ageing
Smoking
Diet salt intake effect on blood pressure
Dietary effect of cholesterol
How does the incidence of lung cancer change with age?
Increases
How does the number of lung cancer deaths attributable to smoking change with age?
Increases
How does blood pressure change with age in a western (high dietary salt) population?
Increasing systolic BP from 20-80yrs old
Increasing diastolic BP before 50 - then decline
Increasing pulse pressure after 50
How does blood pressure change with age in a Tsimane tribe (low dietary salt) population?
Minimal BP changes
Slight systolic BP increase
What do the differences in BP changes over the life-course between high and low salt communities suggest?
Western BP changes with age could be due to abnormally high dietary salt intake
How does blood cholesterol change with age in a Minnesota population?
Increasing levels until 70yrs old - then decline
How does blood cholesterol change with age in a Kyushu population?
Slight increase with age
At all ages lower than in Minnesota population
What are the Minnesota and Kyushu blood cholesterol levels linked to and what does this suggest?
Minnesota - high atherosclerosis levels
Kyushu - very low atherosclerosis levels
Atherosclerosis linked to lifetime dietary habits - not disease of ageing
What are the age-associated effects on the heart?
Increased left ventricle muscle mass (cardiac hypetrophy) - decreased chamber volume
Stiffer left ventricle - fibrosis forms
Enlarged left atrium - increased contraction strength - compromises ventricular filling
Impaired left ventricular relaxation - causes diastolic dysfunction
Increased filling pressures - causes heart failure with preserved ejection fraction
Why might heart failure with preserved ejection fraction (HFPEF) be the result of cardiac ageing?
Often in older people without CHD history
What is HFPEF?
Proportion of blood in left ventricle ejected (ejection fraction) preserved
Left ventricle does not fill with enough blood
What is HFREF?
Decreased proportion of blood ejected from left ventricle
What is HFREF due to?
Weakened heart muscle
What is HFPEF due to?
Left ventricular hypertrophy, fibrosis, microvascular disease - causes smaller chambers and stiffer, thicker walls - impairs relaxation in diastole
How might HFPEF be linked to large artery stiffening?
Could be consequence/cause
More work needed by heart to maintain same stroke volume
What causes cardiac fibrosis in HFPEF?
Neutrophils - contribute to myofibroblast activation - release extracellular matrix proteins - cause fibrosis
How do large arteries change with age?
Stiffening - due to oxi stress and inflammation
What is the effect of large artery stiffening with age?
Ejection into stiffer arteries - causes large pulse pressure increase after 50yrs old
How do small arteries and arterioles change with age?
Decreased number of arterioles, increased arteriole tortuousity - fewer and narrower vessels - increases total systemic resistance
Oxi stress and inflammation - decreases NO production - impairs endothelial vasodilation
How do capillaries change with age?
Fewer capillaries - compromises exchange
Endothelial cell apoptosis - decreases capillary permeability - in brain contributes to cognitive decline
BBB breakdown - allows aberrant factors into brain
How do veins change with age?
Fibrosis and collagen fibres - veins stiffen - decreases venous compliance - decreases venous reservoir
Decreased venodilation - increases central venous pressure
How might vein stiffening be linked to impaired heart filling?
Could be cause/consequence
Stiffening decreases reservoir - increases load on heart
What is the name of the cardiovascular response to going from laying to standing?
Orthostasis
What is the effect of going from laying to standing?
Sudden hydrostatic pressure in lower limbs
Effect mainly experienced by veins as distendable - distend - larger volume trapped within - cannot return to heart - decreases cardiac output - decreases BP
Describe orthostasis in young people
Increased peripheral vasoconstriction, increased heart rate (due to decreased vagal activity) - compensates
Describe orthostasis in old people
Smaller decrease in vagal activity, impaired diastolic filling, impaired sympathetic outflow
Causes smaller rise in heart rate, less arterial vasoconstriction
Causes greater decrease in BP
How does maximum aerobic capacity change with age?
Decreases
What is the main cause of the decline in maximum aerobic capacity with age?
CV function
