15A19: Exam Report

Describe the effects of ageing on the cardiovascular system.

29% of candidates passed this question.

Many candidates described the pathological processes which might affect the aging heart rather than the physiological ones.

Recognition that aging reduces cardiovascular reserve followed up with an outline of the effects of aging on the heart, the vasculature, endothelial function and the conducting system would be rewarded with a good mark.

Few answers quantified the decrease of cardiac output with age and only even fewer ventured into the contribution of ventricular filling by atrial systole. No answer discussed endothelial changes with aging.

Some answers were repetitious. Some answers included a significant discussion of information that was not asked for (Laplace law/Poiseuille’s law).

G6i / 15A19: Outline the cardiovascular changes with morbid obesity

Definition

Ageing is the accumulation of irreversible molecular and cellular damage over time

Cardiovascular Conseqeunces

↓ Vessel Compliance

  • Intima media fibrosis
  • Vessels ↓elasticity
  • ↑ SVR & HTN
  • ↑ LV strain & LVH

↓ Ventricle Compliance

    • Heart muscle replaced by collagen & fat
    • ∴↓ ventricle compliance
    • Ventricle filling dependent on diastolic relaxation which is impaired
    • ∴greater reliance on atrial systole

↓CO

  • ↓3% per decade
  • ↑arm-to-brain circulation time

Arrhythmias

    • ↓no. of cardiac conducting cells
    • Fibrosis of conducting system
    • Loss of SA Nodal PM cells
    • ↑risk arrhythmias, esp. AF/A flutter

β-Adrenoreceptor Down Regulation

  • of receptors unchanged
  • Plasma [NA] ↑ with ↑age
  • Suggesting a deficit in uptake
  • However, attenuation of β-adr stimulation in elderly
  • β agonists have less effect on HR
  • Decreased affinity for receptors

Autonomic Dysfunction

    • Impaired BaroR response
    • Due to stiffening of large arteries
    • ∴HR cannot always respond to maintain BP
    • Postural HypoT common & exacerbated by diuretics, anti-HTNs, hypovolaemia
    • ↓Symp + parasymp efferents

Age Related ↓ HR

  • ↓no. atrial PM cells
  • Unable to ↑CO by ↑HR & rely on ↑SV