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 function

·   Less common; LVH offsets hypoplasia

·   But ↑energy required due to ↑afterload

Diastolic function

·   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

 

 

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