cardiac failure

Question 1

cardiac failure

Answer 1

failure of the heart as a pump to meet the circulatory needs

Question 2

systolic heart failure SHF

Answer 2

a low ejection fraction (EF<40%). the EF= the stroke volume SV divided by the left ventricular end-diastolic volume (LVEDV). normal value ranges from 55-80%

Question 3

ejection fraction

Answer 3

the stroke volume divided by the end diastolic volume. normally 55-75%

Question 4

diastolic heart failure DHF

Answer 4

characterised by a normal EF >60% at rest. in addition there is usually an S4 atrial gallop, due to increased resistance to filling in late diastole. there is an increase in left atrial and left ventricular end-diastolic pressure.

Question 5

left ventricular systolic failure

Answer 5

LV cannot efficiently eject blood into the aorta. this a problem with emptying the heart.. causes an increase in the LVEDV and LVEDP due to increased afterload/preload, this leads to a backup of blood into the lungs producing pulmonary oedema.
LV failure is most commonly systolic failure. most common cause is ischaemia (inadequate blood supply), due to coronary artery atherosclerosis (most common cause), or post MI.

Question 6

left ventricular diastolic failure

Answer 6

problem with filling.

• noncompliant, stiff LV with impaired relaxation defines diastolic heart failure (DHF)
• causes: concentric LV hypertrophy due to essential HTN is most common cause of DHF.

Question 7

right-sided heart failure (RHF)

Answer 7

RV cannot effectively pump venous blood into the lungs either because it cant pump or because it cant fil. blood pools under pressure in the venous system, blood builds up behind the failed heart. increase in RV afterload. most common cause of RHF is LHF.

Question 8

left sided symptoms and signs

Answer 8

1) dyspnoea
2) pulmonary oedema- an increase in LVEDV leads to increase in LVEDP in the LV that is transmitted back into the pulmonary capillaries.
- once pulmonary capillary HP overrides oncotic pressure, a transudate enters the interstitial space and then into the alveoli, producing pulmonary oedema- narrows airways and can produce expiratory wheeze. pink frothy sputum.

Question 9

starling forces and pulmonary oedema

Answer 9

• blood enters capillaries at pressure of ~35mmHg. exits capillaries and enters veins ~15mmHg- drives fluid into interstitium.
• the main force opposing Pc is the osmotic pressure created by plasma proteins (colloid osmotic pressure). values for Pi-C average ~25mmHg. interstitial fluid pressure typically between 0 and -3mmHg

Question 10

left sided symptoms and signs: paroxysmal nocturnal dyspnoea

Answer 10

• dyspnoea at night when laying flat.
• without the effect of gravity, fluid from the interstitial space moves into the vascular compartment.- increases venous return to the right side of the heart and then to the failed left side of the heart leads to pulmonary oedema .
• number of pillows that causes symptomatic relief should be quantitated.

Question 11

Brain Natriuretic Peptides BNP

Answer 11

BNP: cardiac neurohormone secreted from the ventricles and brain when they are volume overloaded and in response to SNS activation.

Question 12

natriuretic peptides

Answer 12

involved in the long-term regulation of sodium and water balance, blood volume and arterial pressure. 2 major actions:

1) vascodilation (of veins- reduced venous return hence ventricular preload.
2) renal effect- leading to Natriuresis and Diuresis- they also reduce renin

Question 13

right sided failure

Answer 13

RV cannot effectively pump venous blood into the lungs. blood pools under pressure in the venous system

Question 14

right sided symptoms and signs

Answer 14

• increased volume in venous system
• prominence of internal jugular veins
• functional TV regurgitation
• stretching of the TV ring from RV vol overload.
• right-sided S3 and S4 heart signs.
• backlog to liver = painful hepatomegaly (liver enzymes will be raised).
• backlog to limbs- dependent pitting oedema- due to increase in venous hydrostatic pressure.
• cyanosis

Question 15

factors that may precipitate heart failure and biventricular failure

Answer 15

• non-adherence to medical treatment

- others = excess fluid water, excess sodium

Question 16

hormonal factors involved in neurohormonal adaptation

Answer 16

mainly RAAS, also ADH Atrial Natriuretic peptide (ANP)

Question 17

sympathetic nervous system

Answer 17

SNS activation occurs very early in the course of the disease.
increased circulation levels of the adrenergic neurotransmitter NE secondary to increased SNS signalling and NE release from adrenergic nerves and subsequent ‘spillover’ into the plasma, as well as reduced uptake by adrenergic nerve endings

Question 18

renal function

Answer 18

increasing salt and water retention by kidneys, leading to pulmonary and peripheral oedema, are hallmarks of worsening heart failure. this oedematous state is not the result of intrinsic renal dysfunction but rather an orchestrated response to increased SNS traffic to the kidney. increased sympathetic activity leads to peripheral vasoconstriction of the afferent renal artery and decreased blood flor to the juxtaglomerular apparatus in the kidney, with resultant release of renin into the afferent arteriole by the juxtaglomerular apparatus

Question 19

tests

Answer 19

• measure their N-terminal pro-B-type natriuretic peptide level.
• arrange 12 lead ECG, most common finding is LV hypertrophy (tall R waves)
• transthoracic echocardiogram- will show whether diastolic or systolic failure.
• CXR