Ageing 5: Cardiovascular & Respiratory

Question 1

How are cardiac systole/diastole affected with age? What structural changes occur to the changes w/ age (+ assoc risks)

Answer 1

• LV hypertrophy (aortic stiffness ↑ afterload)
• ↓ diastolic function (fibrosis + hypertrophy); preserved systolic function
• Increased risk of atrial fibrillation (assoc w/ LA dilation)

Question 2

Changes to cardiomyocytes with age

Answer 2

• Weight of total heart ↑, but regeneration ↓
• Therefore, myocyte hypertrophy ↑
• More collagen and less elastin, leading to fibrosis
• Calcium/amyloid accumulation

Question 3

Changes to arterial vasculature with age

Answer 3

• Increased diameter, but smaller lumen
• Stiffer vasculature (fibrosis)
• Thicker intima-media section due to abberant ECM
• SMC hyperplasia/hypertrophy

Question 4

What happens to calcium within the heart as we age?

Answer 4

• Calcium in heart skeleton decreases
• It has to go somewhere, and accumulates mostly in valvaulr tissue (can cause aortic stenosis) and vascualture

Question 5

How does resting heart rate (and corresponding autonomic function) change with age?

Answer 5

• Intrinsic resting HR decreases with age
• For most of life, parasympathetic needs to dampen down
• In old age, sympathetic may be required to increase HR to meet metabolic demands of the body

Question 6

What causes age-related changes to the cardiac conduction system with age (structurally, cellularly, hormonally)?

Answer 6

• Amyloid/lipid around pacemaker tissue can slow it down
• Electrical/conducting cells gradually replaced w/ collagen and elastin fibres
• Action potential prolongation occurs in cells (longer refraction in old age :) )
• Reduction in adrenergic response (desensitised in response to increase exposure)

Question 7

Main physiological lung changes associated w/ aging

Answer 7

• Reduced elastic recoil (less deflation after inflation)
• Reduced compliance of the chest wall
• Reduced strength of respiratory muscles

(Harder to breathe in, harder to breathe out)

Question 8

True or false: Margaret is 80 years old - this means she will be more able to detect hypoxia/hypercapnia than she was at the age of, say, 45.

Answer 8

• False
• Ability to detect hypoxia and hypercapnia reduce w/ age

Question 9

What are the two possible factors that can affect elastic properties of the lung? Which change with age to produce the effect that’s seen?

Answer 9

• Two properties are surface forces/tissue forces
• Surface forces/tension unchanged, but tissue forces change, resulting in reduced elastic recoil w/ age

Question 10

What is thought to cause the decrease in chest wall compliance with age

Answer 10

• Calcification of costal cartilages
• ↑ stiffness of rib vertebral articulations

Question 11

What causes weakened action of respiratory muscles in older people, mechanistically?

Answer 11

• Kyphosis + barrel chest reduce mechanical advantage
• Age-related diaphragmatic weakness
• Increased FRC (WIT?); ↑ elasitc load from chest wall
• Can also be caused by undernutrition and CHF

Question 12

Theory as to why lung parenchyma elastic recoil decreases with age

Answer 12

• Not necessarily to do with fibrosis/scarring
• Instead, perhaps due to reduced cross-linking of these collagenous fibres + psuedoelastin presence

Question 13

Changes in RV, VC, and TLC with age (resp)

Answer 13

• RV increases (reduced elastic recoil)
• VC decreases (also reduced elastic recoil)
• TLC remains unaffected (can still blow out birthday candles)

Question 14

How do FEV1 and FVC change with age after ~20/25?

Answer 14

Decrease

Question 15

True or false: age has appreciable change on airway resistance

Answer 15

False.

Question 16

How do fundamental gas exchange mechanics in the lung change with age? Does this affect PaO2?

Answer 16

• Increased areas of VQ mismatch (what are the two types of this, Mr. Crit Care?)
• Results in lower PaO2