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CVS > Lecture 19 > Flashcards

Lecture 19 Flashcards

1
Q

What is heart failure?

A

Inability of the heart to meet the demands of the body (deliver a blood volume that allows body tissues to function as required)

-clinical syndrome (collection of signs and symptoms) of reduced cardiac output, tissue hypoperfusion, increased pulmonary pressures, tissue congestion

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2
Q

What enables the heart to work as an effective pump?

A
  • one way valves
  • chamber size (big enough to allow filling of blood)
  • functioning muscle (adequate muscle, coordinated contraction)

Anything interfering with these can cause impairment of cardiac function

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3
Q

What is the most common cause of heart failure?

A

Ischaemic heart diseases (coronary arteries)

MI is also common leading to fibrosis: stiffening

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4
Q

Common causes of heart failure?

A
  • hypertension (increased afterload on ventricles: hypertrophy/risk factor for atherosclerosis)
  • arrhythmias
  • aortic stenosis (increased afterload on ventricles)
  • cardiomyopathies (disease of heart muscle: dilation/hypertrophic)
  • pericardial disease
  • valvular/structural diseases (acquired/congenital)

Rarely can occur in grossly elevated demand on cardiac output (sepsis, severe anaemia, thyrotoxicosis:excess of TH)

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5
Q

Equation to work out CO:

A

CO= SV x HR
SV: how much you eject by ventricle in single beat
-only a fraction of the blood that was sat in the ventricle during diastole is ejected leaving the end diastolic volume (EDV)
-EJECTION FRACTION
CO: volume expelled per ventricle per min

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6
Q

What influences SV?

A

Increase SV

  • pre-load increased (volume in ventricle at end of diastole:stretch on ventricle just before contraction)
  • myocardial contractility

Decrease SV
-increased after-load (TPR)

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7
Q

What is Frank-Starling’s law?

A

Increased EDV = greater CO
(Intrinsic property of cardiac myocytes: greater they are stretched, the greater the force of contraction, up to a certain point)

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8
Q

What nervous system increases contractility of the heart?

A

Activation of sympathetic nervous system

  • increased sympathetic activity, greater the contractility= greater CO
  • this means frank-stirlings curve is shifted up and to the left
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9
Q

Why is the CO reduced in heart failure?

A

SV is reduced

  • reduced preload (due to impaired filing of ventricle- not due to little blood returning to the ventricle)
  • reduced myocardial contractility
  • increased after-load
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10
Q

What are the two broad reasons why the heart can fail?

A 
Filling problem (diastolic)
-Ventricular capacity for blood is reduced: ventricle walls too stiff/not relaxing enough/ventricle walls thickened: hypertrophy (EDV/preload reduced)

Contractility (ejection) problem
-heart can’t pump with enough force (no change in size of ventricle), muscle wall is thin/fibrosis, chambers enlarged/overstretched, abnormal/uncoordinated contraction)

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11
Q

What is the difference between systolic/diastolic heart failure?

A

Systolic heart failure
-weakened heart muscle: contractility/ejection problem
Diastolic heart failure
-filling problem

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12
Q

How do you classify heart failure?

A

HFrEF (heart failure with reduced ejection fraction)

  • systolic dysfunction
  • contractility problem

HFpEF (heart failure with preserved ejection fraction)

  • diastolic dysfunction
  • filling problem (still as a percentage eject most of blood from ventricle but you are working with a smaller volume of blood)
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13
Q

What is the most common type of heart failure?

A

HFrEF

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14
Q

What is a normal ejection fraction?

A

> 50% (usually 60-70%)

Abnormal is <40%

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15
Q

How do you work out ejection fraction?

A

Measured on an echocardiogram

Amount of blood pumped out of the ventricle/total amount of blood in the ventricle

SV/EDV

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16
Q

How do you classify heart failure according to ventricles involved?

A

LV: most commonly involved, with subsequent involvement from right ventricle
Biventricular/congestive: both ventricles
RV: can occur in isolation secondary to chronic lung diseases (most common cuase it LV heart failure)

17
Q

How does increased ventricular filling effect CO in a failing heart?

A
  • increased ventricular filing in a failing heart= minimal gains, little increase in CO
  • worsens CO
18
Q

How does neuro-hormone activation affect the heart?

A
  • helpful in heathy heart

- unhelpful in unhealthy heart as it increases cardiac work

19
Q

What negative feedback does decreased CO evoke?

A

Low BP

  • baroreceptors detect in carotid sinus
  • increased sympathetic drive (increasing HR and TRP)
  • increasing afterload
  • increasing cardiac work
  • activation of RAAS pathway
  • vasoconstriction and enhanced sympathetic activity (increasing afterload)
  • stimulates ADH and increase circulating volume due to Na+ and a water retention via aldosterone (increases pre-load)
  • increasing cardiac work

Not good for failing heart but good for healthy heart

20
Q

Signs and symptoms of heart failure:

A
  • fatigue/lethargy
  • breathlessness
  • increased interstitial fluid (oedema in pulmonary tissues/maybe peripheral tissues)
21
Q

How does tissue fluid form?

A

Due to high arterial pressure: hydrostatic forces greater than oncotic forces= net movement of fluid into interstitium

-venule end hydrostatic pressure falls so fluid is pulled back into vessel a oncotic pressure is now higher

Oncotic pressure remains same as proteins stay in vessel

22
Q

Why does oedema occur in heart failure?

A

Increased capillary hydrostatic pressures at venule end leads to less fluid being drawn back into venule end
-due to failing left/right ventricle

23
Q

Specific symptoms involved in left/right ventricular heart failure:

A

LVHF: (blood returning back to lungs, so backlog there)

  • fatigue/lethargy
  • breathlessness (exertional)
  • orthopnoea (breathlessness when lying down)
  • paroxysmal nocturnal dyspnoea (waking in night gasping for breath)
  • basal pulmonary crackles: pulmonary oedema
  • cardiomegaly (displaced apex- indicating enlarged LV)

RVHF: (blood returning back from rest of body)

  • fatigue/lethargy
  • breathlessness
  • peripheral oedema (pitting)
  • raised jugular venous pressure
  • tender/smooth enlarged liver(liver congestion)
24
Q

What happens to Frank-Starling’s law in heart failure?

A
  • increased LV filling in failing heart leads the very little increase in CO: shallow gradient (normally it increases CO)
  • eventually leads to CO worsening: curve dips
  • increased EDV resulting in falling CO and pulmonary congestion
25
Q

What is pressure in the right internal jugular vein used as a reflection of?

A

Pressure in the right side of the heart

CVS (16 decks)

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