CVS 11.1 - Heart Failure Flashcards Preview

ESA 2 > CVS 11.1 - Heart Failure > Flashcards

Flashcards in CVS 11.1 - Heart Failure Deck (25):
1

What is heart failure?

A state in which the heart fails to maintain an adequate circulation for the needs of the body despite an adequate filling pressure

2

How does ischaemic heart disease lead to heart failure?

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3

How does hypertension lead to heart failure?

- Causes LV hypertrophy which then dilates

- Chronic increased afterload = decreased ventricular compliance

- Increases oxygen demand of the myocardium

4

How does dilated cardiomyopathy lead to heart failure?

- LV becomes large and weakened

- ↓ pumping ability of hypertrophic part

- ↓ function

5

How does valvular heart disease lead to heart failure?

- Stenosis of blood in the atria = Doesn't drain properly

- ↑ stretch of the myocardium

- Stretches enough to damage electrical conducting system

6

How does pericardial disease lead to heart failure?

- ↑ fluid between heart and pericardium

- ↑ intrapericardial pressure

- Causes ↑ SV so ↑ CO

7

Give an example of high output heart failure and describe how it can lead to heart failure

- Anaemia

- ↓ haemoglobin = ↑ work load of heart to compensate for ↓ O2

- Puts extra pressure on the mitral valve

8

How does heart failure progress?

- Class 1 = no symptoms, physical activity isn't limited

- Class 2 = physical activity slightly limited resulting in symptoms (not at rest)

- Class 3 = Limited physical activity, less than normal resulting in symptoms (none at rest)

- Class 4 = Can't exercise with symptoms, ↑ with activity and are present at rest

9

What is the value for cardiac output?

5 litres/minute

10

What is the value for stroke volume?

75ml/beat

11

What is the value of LV eSV?

~75ml

12

What is the value of LV eDV?

~150ml

13

What is ejection fraction?

The percentage of blood ejected from each ventricle per contraction (50%)

14

What is starling's law? How does this relate to heart failure

- The force developed in a muscle fibre is dependent on the degree to which the fibre is stretched i.e. volume of blood

- HF = ↓ force for the same amount of volume

15

What is systolic dysfunction? How is it caused?

- Left ventricular ejection fraction becomes lower than 40% due impaired ventricular contraction

- Myocardial wall becomes thinner due to fibrosis/necrosis (↑ type 1-3 collagen) and matrix proteinases

16

What happens to cardiac output and LV capacity as a result of systolic dysfunction?

- LV capacity increases

- LV Cardiac Output decreases

17

What changes can occur to cause systolic dysfunction?

- Dilatation of the left ventricle

- Pulls cusps of the mitral valve apart = dysfunction

- ↑ risk of cardiac dysrrhythmias

18

What are the structural changes involved in heart failure?

- Globalised remodelling (dilatation) leading to localised thinning. Acute infarction = ↓ skeletal muscle blood flow so ↓ skeletal muscle mass

- Diastolic heart failure due to hypertrophy of left ventricle -> becomes smaller so can hold less volume and becomes stiff

19

What are the cellular changes involved in heart failure?

- Myocyte hypertrophy

- Irregular Ca2+ regulation

- ↑ Na+, angiotensin 2 and cytokines

- Release of troponin C

20

How does stimulation of the sympathetic nervous system lead to an increased cardiac output?

- Beta-1 activation in heart = +ve chronotropic effect (↑HR)

- Beta-1 activation in heart = +ve inotropic effect (↑ contractility)

- Alpha-1 activation in vascular smooth muscle = vasoconstriction of arteries so ↑ workload (↑ preload and afterload)

21

How can sympathetic stimulation become detrimental?

- Leads to downregulation of beta adrenoceptors

- Noradrenaline promotes formation of fibrosis and hypertrophy and promotes ↑RAAS

22

What is the function of angiotensin 2?

- Promotes LV hypertrophy and myocyte dysfunction

- Causes vasoconstriction

- Causes aldosteron release (Na+ and H2O retention in the kidneys = ↑BV)

23

How does bradykinin contribute to the cardiovascular system?

- Promotes natriuresis (Na+ excretion in the urine)

- Promotes vasodilation

- Stimulates prostaglandin production

- Stimulates NO production

24

What are natiuretic hormones?

- Polypeptide hormones (endocrine and paracrine) secreted by cardiac myocytes in response to ↑ stretch for powerful vasodilation

- Maintain blood pressure and extracellular blood volume

25

What do natiuretic hormones promote?

- Inhibition of aldosterone and renin

- Natiuresis

- Constriction of afferent arterioles

- Dilation of efferent arterioles

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