2019A02 Describe the cardiovascular changes that occur with ageing.

List:

· Intro

· Heart

· Blood vessels

· Haemodynamics

· Autonomics

· Electrics

Intro:

· Ageing: gradual time-dependent loss of cellular function and physiological reserve, resulting in death

· Overall: ↓ CVS reserve. CVS decline attenuated with training.

Heart:

Structure	· Concentric LV hypertrophy o (Stiff aorta = ↑LV afterload) o ↑force of contraction o ↓compliance o ↑LVEDP · Hypoplasia o Apoptosis and necrosis o ↓Force of contraction
Systolic dysfunction	· Less common; LVH offsets hypoplasia · But ↑energy required due to ↑afterload
Diastolic dysfunction	· Very common · LVH -> ↓compliance -> ↑filling pressure required -> Poor tolerance of hypovolaemia, PPV -> More dependent upon atrial kick (note ↑risk AF also)
Pre-conditioning	· Mechanism: activation of sarcolemmal and mitochondrial K⁺-ATP channels -> hyperpolarisation -> ↓ICF [Ca²⁺] · Attenuated with ageing
Common comorbidities	· Ischaemic heart disease o Poor tolerance of tachycardia e.g. laryngoscopy, extubation · Cardiomyopathies: o Poor tolerance of neg inotropes e.g. propofol · Valvular pathology o Poor tolerance of vasodilators e.g. propofol · Arrhythmias

Blood vessels:

Structure

· Atherosclerosis

· Intima thickened, fibrotic

· Media thickened, less elastin

· Vessels dilated, elongated, tortuous

Function

· Impaired NO release

· Impaired relaxation / autoregulation

· ↑SVR

· ↑PVR and ↑heterogeneity of perfusion

Common comorbidities

· Atherosclerosis: build-up of fat, cholesterol, calcium in vessel walls

· Aneurysms: due to dilatation, ↑tension (LaPlace’s law)

Haemodynamics:

Heart rate

· ↓Resting HR

· ↓Max HR = 220 – (age x 0.7)

Cardiac output

· At rest: variable ↓

o Remains proportional to lean mass

o Attenuated if fit

· In exercise: ↓20%

o Multifactorial

o Poor tolerance of stress, SIRS, major surgery

Blood pressure

· ↑Systolic BP, ↓diastolic BP, ↑pulse pressure

o ↓Elastin, ↓compliance, ↓Windkessel effect

· ↑Pulse wave velocity

o ↓Aortic-radial delay

o May contribute to ↑afterload

Autonomics:

Cellular changes

· ↓β₁ adrenoceptors

· ↓Post-adrenoceptor signaling

· ↓Catecholamine re-uptake

· ↑Circulating [noradrenaline]

Functional changes

· ↓HR, contractility reserve

· ↓Ability to vasoconstrict/-dilate

· ↓Baroreceptor response, and delayed

Implications

· ↓Tolerance of Valsalva, PPV, hypovolaemia

Electrics:

Structure

· Fatty and fibrous infiltration of SA node, AV node, bundle branches

· ↓Pacemaker cells in SA and AV nodes (50% age 20, 10% age 75)

Function

· Risk of sick sinus syndrome, AV block

· Risk of AF due to LA enlargement