Heart Failure

Question 1

Define HF

Answer 1

An abnormality of cardiac structure/function leading to failure of the heart to deliver enough O2 to meet metabolic and physiological demands despite normal filling pressures

Question 2

Define forward failure

Answer 2

reduced CO

Question 3

When does forward failure occur?

Answer 3

When the LV contracts and cannot exert sufficient CO

Question 4

Define backward failure

Answer 4

elevated A/V filling pressures

Question 5

When does backward failure occur?

Answer 5

When either ventricles contract and are unable to reject all blood from chambers -> returning blood cannot refill due to no space

Question 6

Describe HF-REF (systolic HF)

Answer 6

• reduced LVEF <40%

- inability of the heart to contract effectively

Question 7

Describe HF-PEF (diastolic HF)

Answer 7

• normal LVEF > 40%

- inability of the heart to relax effectively

Question 8

Describe the difference between acute and chronic HF

Answer 8

• rapid onset (hrs/days)
• sudden decline in cardiac function
• potentially life threatening
• chronic is slow onset (months/years)

Question 9

State 4 causative factors of HF-REF

Answer 9

• intrinsic myocardial damage
• pressure overload
• volume load
• inadequate filling

Question 10

Describe the pathophysiology of HF-PEF

Answer 10

Occurs a result of multiple comorbidites such as obesity, HPT, AF, Type 2 diabetes

Question 11

State & describe 3 pathophysiological mechanisms of HF-REF

Answer 11

• cardiorenal model - fluid retention secondary to forward failure & reduced renal BF
• cardio-circulatory model - forward failure due to peripheral vasoconstriction & increases PVR
• neurohormonal model - maladpative neurohormonal activation -> cardiac remodelling

Question 12

Describe how the neurohormonal model works

Answer 12

• Cardiac injury reduces CO output -> reduced BP & organ perfusion
• reflex activation of several neurohormonal pathways which are initially beneficial but then become harmful
• progressive deterioration of cardiac function

Question 13

Describe the effects of the neurohormonal model on the sympathetic nervous system

Answer 13

• Increase in catecholamines, myocardial contractility, HR, systemic & pulmonary vasoconstriction
• Increased secretion of renin from juxtaglomerular apparatus of kidney activates RAAS

Question 14

What effect do catecholamines (adrenaline & noradrenaline) have?

Answer 14

aggravates ischaemia, potentiate arrhythmias, directly toxic to myocytes, promote cardiac remodelling

Question 15

Describe the renin-angiotensin-aldosterone system

Answer 15

• increased angiotensin II increases systemic vasoconstriction and peripheral SNS activation
• increased aldosterone increases Na & H2O retention, endothelial dysfunction, organ fibrosis
• angiotensin II & aldosterone are directly toxic to cardiac myoctyes & promote cardiac remodelling

Question 16

What happens as a result of increased ADH release?

Answer 16

Increased water retention & vasoconstriction

Question 17

describe the 2 symptom complexes of clinical features of HF

Answer 17

Reduced CO - hypoperfusion symptoms
- fatigue & decreased exercise tolerance

Impeded venous return - congestive symtpoms

• pulmonary & systemic congestion
• ankle oedema, cough, elevated JVP

Question 18

Describe the classification & staging of HF

Answer 18

classification Class I (asymptomatic) -> Class IV (severe)

staging stage A (high risk) -> Stage D (end/refractory)

Question 19

State the different drugs used to manage chronic HF and which model they apply to

Answer 19

Cardiorenal - diruetics, inotropes
Cardiocirculatory - inotropes, vasodilators
Neurohormonal - ACEIs, BBs, ARBs, ARNIs, aldosterone antagonists

Question 20

Describe the integrated approach for management of chronic HF

Answer 20

general measures:

• Reduces cardiac workload
• Restrict dietary salt & fluid intake
• Smoking cessation & alcohol moderation

Drug therapy
Other - heart transplant

Question 21

List the treatment goals for CHF

Answer 21

• improve CO (decrease forward failure)
• reduce A/V filling pressures
• stop/reverse cardiac remodelling

Question 22

State 3 treatment strategies of HF

Answer 22

• myocardial stimulation
• reduce cardiac workload
• arrest/reverse cardiac remodelling

Question 23

Describe the treatment of myocardial stimulation

Answer 23

increases myocardial contractility with inotropic agents

Question 24

Describe treatment of reducing cardiac workload

Answer 24

reduces afterload/preload with diuretics/vasodilators

Question 25

Describe how cardiac remodelling is reversed

Answer 25

inhibits chronic neurohormonal activation with ACEIs, BBs, ARBs, ARNIs, aldosterone antagonists