Past Papers · SAQ
Cardiovascular Responses — Ageing
2022B Q12
Exam questionDescribe the effects of ageing on the cardiovascular system.
CICMWrecks answer
Master answer
Ageing = physiological time-dependent process which results in ↓ cellular function + ↓ reserve
- Heart
- ↑ fibrous infiltration of myocardium → ↓ ventricular compliance (esp LV > RV)
- ↓ # myocytes but compensated by hypertrophy → ↑ myocardial wall thickness (concentric) → ↓ ventricular compliance (esp LV > RV)
- ↑ fibrous infiltration of endocardium → ↓ ventricular compliaince (esp LV > RV)
- Calcification of heart valves → valvular incompetence (stenosis/regurgitation)
- Conducting system (Ie. SAN, AVN, bundle of His, Purkinje):
- ↑ fibrous/fatty infiltration
- ↑ loss of pacemaker cells
- ↓ # and sensitivity of β receptors within pacemaker cells
- Peripheral vasculature:
- ↓ elasticity of large arteries due to thickening and calcification of vessel wall
| Change with ageing | Reason | |
|---|---|---|
| HR | Resting HR → unchanged ↓ maximum HR (Max. HR = 220 – age) ↑ arrhythmias (AF, AV heart block, VEBs, BBB) | Conduction system (SAN, AVN, bundle of His, Purkinje) → fibrous/fatty infiltration and loss of pacemaker cells ↓ # and sensitivity of β receptor of pacemaker cells |
| SV | ↓ resting SV ↓ maximum SV | ↓ ventricular compliance (2° to fibrous infiltration of myocardium/endocardium, and ventricular hypertrophy) Valvular disease |
| CO | ↓ due to preconditioning (Ie. sedentary lifestyle) or age-related disease Unchanged in “healthy” subjects Nb. ↑ C.O. occurs mainly by ↑ SV (preload) via Frank-Starling mechanism (rather than ↑ HR) | ↓ HR – see above ↓ preload (↓ SV) – see above ↑ afterload (↑ SVR) – see below ↑ reliance on “atrial kick” (30% of C.O. vs 5% in adults) → AF/↑HR not well tolerated |
| BP | ↑ MAP and SBP DBP ↑ slightly (until age 60), then ↓ ↑ pulse pressure (due to ↑ SBP > DBP) | ↓ elasticity of large arteries due to thickening and calcification of vessel wall |
| Pulmonary circulation | ↑ PAP a/w ↑ PVR | |
| Control of CVS | ↓ maximum exercise tolerance (due to age-related ↓ maximum HR, SV, C.O.) Impaired BRR → postural hypotension ↓ β receptor response of CVS to catecholamines (↓ # or affinity of receptor, ↓post-receptor signalling, ↓ myocardial contractile response with stimulation) ↑ vagal tone |
Bianca 2016
Past papers