Module outline - Anatomy - Myocytes - Cardiac cycle - - - PowerPoint PPT Presentation

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Module outline - Anatomy - Myocytes - Cardiac cycle - - - PowerPoint PPT Presentation

Jul 30, 2023 363 likes •496 views

Module outline - Anatomy - Myocytes - Cardiac cycle - Haemodynamics & blood pressure - Coronary circulation - Capillaries One 2 One Medicine: Pre-clinical revision course One 2 One Medicine: Pre-clinical revision course Cardiac cycle

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SLIDE 1

One 2 One Medicine: Pre-clinical revision course

  • Anatomy
  • Myocytes
  • Cardiac cycle
  • Haemodynamics & blood pressure
  • Coronary circulation
  • Capillaries

Module outline

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SLIDE 2

One 2 One Medicine: Pre-clinical revision course

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SLIDE 3

One 2 One Medicine: Pre-clinical revision course

End diastolic volume End systolic volume Stroke volume

Cardiac cycle

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SLIDE 4

One 2 One Medicine: Pre-clinical revision course

  • Preload/EDV

determines SV

  • Length tension

relationship = EDV

  • Filament overlap
  • Symp ↑ SV for any

given EDV

20 40 60 80 100 20 40 60 80 100 120 140 160 180 200 Stroke volume (ml) End-distastolic volume (ml)

Increased sympathetic activity

Force of contraction Contractility

Frank-Starling law of the heart

16

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SLIDE 5

One 2 One Medicine: Pre-clinical revision course

20 40 60 80 100 20 40 60 80 100 120 140 160 180 200 Stroke volume (ml) End-distastolic volume (ml)

Increased sympathetic activity

Force of contraction Contractility

Frank-Starling law of the heart

Factors affecting EDV:

  • Venous tone
  • Blood volume
  • Skeletal muscle pump
  • Respiratory pump
  • Posture
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SLIDE 6

One 2 One Medicine: Pre-clinical revision course

  • = Cannot meet metabolic demand (at normal CVP)
  • Causes of heart failure:
  • Ischaemic heart disease
  • Hypertension
  • Valvular disease

Heart failure

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SLIDE 7

One 2 One Medicine: Pre-clinical revision course

Stroke volume (ml) 20 40 60 80 100 End-distastolic volume (ml) 20 40 60 80 100 120 140 160 180 200

Heart failure

Heart failure

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SLIDE 8

One 2 One Medicine: Pre-clinical revision course

  • Fluid retention → ↑ blood vol ∴

CVP

  • → RIGHT on Starling’s curve
  • Initially: ↑ SV
  • Late: dilated w/o ↑SV
  • Remodelling (RAAS)

Heart failure

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SLIDE 9

One 2 One Medicine: Pre-clinical revision course

RAAS: (↓renal perfusion)

  • Fluid & Na+ retention
  • Ang-II ➙ Constriction

Sympathetic activation

  • A ➙ Renin (β1)
  • ↑ Contractility
  • ↑ HR (inc. ↓ Vagus)
  • NA ➙ Vasoconstriction

∴ ↑ AFTERLOAD* ➙ ↑ ENERGY & ↓

Heart failure

*Afterload = total peripheral resistance

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SLIDE 10

One 2 One Medicine: Pre-clinical revision course

Heart failure

Right-sided heart failure Left-sided cardiac failure Raised jugular venous pressure Pulmonary oedema Hepatomegaly Peripheral hypoperfusion Peripheral oedema Orthopnoea Ascites Paroxysmal nocturnal dyspnoea Fatigue Cough & wheeze

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SLIDE 11

One 2 One Medicine: Pre-clinical revision course

  • Pacemaker cells have a depolarising pre-potential

due to high sodium permeability

  • End-diastolic volume (pre-load) determines force of

contraction by controlling myocyte length

  • Sympathetics increase SAN rate, reduce AVN delay

and increase ventricular contractility

  • Heart failure causes right- & down-wards shift on

Frank-Starling curve

Key points