Heart failure

Question 1

Heart failure

Answer 1

heart is unable to meet its metabolic demands for oxygen

Question 2

Ejection fraction

Answer 2

stroke volume / total volume x 100
• 50-70% - normal
• 40-50% - borderline heart failure
• <40% -heart failure

Question 3

Frank starling mechanism

Answer 3

• ventricular filling during diastole
• stretches cardiac muscle
• increases the force of contraction

Question 4

Right sided heart failure

Answer 4

• caused by left sided heart failure

- caused by fluid build up and increased pressure in pulmonary arteries

Question 5

Diastolic heart failure

Answer 5

heart is not filling enough during diastole

Question 6

Systolic heart failure

Answer 6

blood is not being pumped hard enough during systole/contraction

Question 7

(diastolic) left sided heart failure

causes

Answer 7

RESTRICT SIZE OF VENTRICLE

1. long standing hypotension - causes concentric hypertrophy of cardiac muscle so it crowds cardiac muscle, less room for blood
2. Restrictive cardiomyopathy -cardiac wall becomes stiffer and less complaint thus cannot stretch to fill
3. Myocardial fibrosis - fibrosis/scar tissue develops in inner lining of heart
4. Cardiac tamponade

Question 8

(systolic) left sided heart failure

Answer 8

DAMAGE TO MYOCARDIUM
1. Ischaemic heart disease, long standing hypertension, aortic stenosis/regurg

• higher arterial pressure in aorta, harder for left ventricle to pump blood out into high blood pressure -> LV hypertrophy
• build up of muscle mass -> squeezes coronary vessels -> supress O2 supply
• more muscle -> more O2 demand

2. Dilated cardiomyopathy
   • ventricle grows and stretches out muscle wall, too thin to pump blood

Question 9

Ejection fraction in heart failure

Answer 9

1. Remain normal in DHS 
• stroke volume is low
• total volume is low - abnormal filling of the ventricle
2. Reduced in SHF
• Stroke volume is low
• Total volume is normal

Question 10

right ventricular failure

Answer 10

1. left to right cardiac shunt - blood can flow from high pressure to low pressure
2. increases fluid volume
3. concentric hypertrophy of right ventricle
   - > systolic dysfunction - more prone to ischaemia
   - > diastolic dysfunction - smaller volume, less compliant

Question 11

compensatory mechanism of heart failure

Answer 11

1. RAAS
   • heart failure reduces blood flow to the kidneys
   • activates RAAS -> fluid retention -> increases preload -> increased contraction strength
   • Long term : high fluid retention causes it to leak out of vessels and fluid builds up in the lungs
   - increased pressure in pulmonary vessels -> pulmonary oedema
2. Adrenergic nervous system
   • baroreceptors pick up fall in BP, sympathetic putflow to the heart is increased -> vasoconstriction

Question 12

serum markers of heart failure

Answer 12

ANP - stored in atrial cells in response to atrial distention
BNP ( brain naturetic peptide) - not detected in normal heart but produced when myocardium is under haemodynamic stress /heart failure/MI
- inhibits renin production, antagonism of aldosterone, excretion of sodium and water is increased
- reduced blood volume and systemic vascular resistance -> vasodilation

Question 13

isolated right ventricular failure

Answer 13

• > in response to hypoxia pulmonary arteries constrict
• > increased pulmonary blood pressure
• > harder for right ventricle to pump -> RV hypertrophy
• > Right ventricular failure

Question 14

Symptoms of right ventricular failure

Answer 14

• Jugular venous distention
• Hepatosplenomegaly
• Ascites