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Cardiovascular Block: Cardiology (Karen) > Cardiac Failure > Flashcards

Cardiac Failure Flashcards

1
Q

What are the four determinants of CO?

A
  1. Input from venous return PRELOAD
  2. HEART RATE
  3. Strenght CONTRACTILITY
  4. Resisitance AFTERLOAD
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2
Q

What is normal CO?

A

5L/min

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3
Q

How is right ventricular EDP (end diastolic pressure) measured?

A

Approximated by jugular venous pressure (JVP)

at the end of diastole, RA pressure = RV pressure = JVP = end diastolic ventricular P

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4
Q

How is left ventricular EDP (end-diastolic pressure) measured?

A

Pulmonary artery wedge pressure (PAWP)

at the end of diastole:

LA pressure = LV pressure = pulmonary artery wedge pressure = LVEDP

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5
Q

What does pulmonary arterial wedge pressure measure?

A

pulmonary venous pressure

the balloon occludes the artery such thant only venous and capillary pressure are present

this tells us the LA EDP which = LV EDP

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6
Q

Where is PAWP measured?

A

In the pulmonary artery:

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7
Q

What is preload?

A

end diastolic pressure

LV EDP is equivalent to:

L atrial P

Pulmonary venous P

PAWP

RV EDP is equivalent to:

RA P

JVP

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8
Q

LV EDP is equivalent to:

A

LA P

PV P

PAWP

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9
Q

RV EDP is equivalent to:

A

RA P

JVP

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10
Q

Hydrostatic Pressure

A

Pressure pushing fluid out of a capillary

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11
Q

Osmotic Pressure

A

Pressure exerted by proteins in blood plasma; draws fluid into the vessel

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12
Q

Oedema is caused by

A

increases in venous pressure pushing fluid out of vessels/capillaries

(remember that atrial pressure is knocked off by the arterioles)

This occurs in:

heart failure (+venous return, -CO, +venous P)

kidney failure (proteinuria causes -protein tf -osmotic pressure)

liver failure (-albumin/proteins in plasma)

blocked lymphatics (cancer)

increased capillary permeability (infection)

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13
Q

EDP is a measure of

(two things)

A
  1. ventricular filling
  2. venous pressure driving fluid out of capillaries

e.g. LVEDP = preload: LV function

and LVEDP = LAP = PVP: lung capillaries

e.g. RVEDP = preload: RV function
RVEDP = RAP = JVP: peripheral capillaries

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14
Q

Pulmonary congestion occurs when

A

LV EDP is greater than pulmonary venous pressure

–> fluid out of pulmonary capillaries into lungs

due to hydrostatic:oncotic imbalance

~20-30mmHg

n: ~5-10mmHg

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15
Q

Cardiac Failure

A

When CO is less than body needs

usually due to a systolic failure and decreased contractility

CO for a specific degree of filling is lower i.e. less CO for any given ventricular filling (see graph)

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16
Q

Contractility

A

Force of contraction for any given preload and afterload

17
Q

What is the mechanism of compensation in cardiac failure?

A

+EDP to maintain CO

by retaining fluid to increase venous return

EDP >20-25+mmHg leads to congestion

leads to shortness of breath

18
Q

What is the most common cause of cardiac failure in Australia?

A

Ischaemic heart disease

19
Q

What are the causal mechanisms of cardiac failure?

A

Loss of mocardial muscle:

  • ischaemic heart disease leading to MI (most common)
  • cardiomyopathy (especially dilated form)

Pressure overload (causing hypertrophy):

  • aortic stenosis
  • hypertension

Volume overload:

  • valve regurgitation
  • shunts (e.g. septal defects)
20
Q

What are the causes of cardiac failure?

A
  • ischaemic heart disease –> MI
  • valvular heart disease
  • hypertensive heart disease
  • congenital heart disease (shunts, rearranged anatomy)
  • cardiomyopathy
  • cor pulmonale (RHF due to lung disease e.g. long-term lung disease causing right heart hypertrophy)
  • pericardial disease (thickening of or fluid in pericardium)
21
Q

What are the clinical features of LEFT cardiac failure?

A
  • Shortness of breath
  • Fatigue
  • Tachycardia
  • Lung crepitus
22
Q

What are the clinical features of RIGHT cardiac failure?

A

Peripheral oedema (mainly; swollen ankles)

23
Q

What are the ‘inappropriate adaptations’ to cardiac failure?

A

essentially, do more harm than good:

  • Na+ and H2O retention (tf K+ loss = hypokalemia)
  • Vasoconstriction (shunt blood to organs) = increased afterload
  • hyperactivity of SNS & renin-angiotensin-aldosterone systems
24
Q

How does the renin-angiotensin-aldosterone system affect cardiac failure?

A

leads to fluid retention:

  • -CO
  • -renal BF
  • +renin: ang I–>ang II
  • +aldosterone
  • +fluid retention, Na+ retention
  • K+ loss
  • vasoconstriction (angiotensin)
25
Q

How does the SNS affect cardiac failure?

A
  • increased NA
  • initial +contractility
  • long term:
    • vasoconstriction
    • ventricular arrhythmias
    • ventricular fibrillation
    • sudden death
    • toxic to myocardium
26
Q

What is the mechanism of left heart failure?

A
  • Na+ & water retention
  • +LVEDP to +CO
  • +LAP –> +PVP
  • fluid leakage in capillaries –> lung interstitium and alveoli
    • pulmonary congestion
    • shortness of breath
27
Q

What is the mechanism of right heart failure?

A
  • Na+ and water retention
  • +RVEDP –> +RAP –> +JVP
  • peripheral oedema
  • liver congestion
28
Q

What are the causal mechanisms of right heart failure?

A
  • heart disease e.g. cardiomyopathy
  • right heart disease:
    • RV cardiomyopathy
    • R valves, shunts
    • Pericardial disease
    • Arterial pulmonary hypertension
    • Lung disease (Cor Pulmonale)
    • Pulmonary embolism
29
Q

By what mechanism does LHF cause RHF?

A
  • pulmonary venous hypertension
  • pulmonary congestion
  • chronic hypoxia
  • pulmonary vasoconstriction
  • pulmonary arterial hypertension
            = right heart failure
30
Q

What is cor pulmonale?

A

Pulmonary heart disease

enlargement & failure of RV in response to pulmonary hypertension

31
Q

What is diastolic heart failure?

A

reduced LV compliance (MI scar, stiffening due to HT or HyT)

tf increased LVEDP required to fill LV

tf +pulmonary venous pressure

(normal systolic function)

32
Q

What is the treatement of cardiac failure?

A

Reduce fluid by to decrease preload and vasodilate to reduce afterload by:

  • diuretics e.g. frusemide
  • aldosterone antagonists e.g. spironolactone
  • ACE inhibitors e.g. captopril, ramiprol
  • angiotensin receptor antagonists e.g. irbesartan, candesartan
33
Q

Digoxin

A

mildly increases contractility

34
Q

Beta blockers are used in cardiac failure to

A

block effects of NA on the heart

35
Q

What are the common surgical interventions in cardiac failure?

A
  • coronary artery bypass
  • valve replacement
  • biventricular pacemaker
  • implantable defibrillator
  • heart transplant
  • assist devices & artificial hearts

(also tx by -HT)

Cardiovascular Block: Cardiology (Karen) (4 decks)

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