Chronic heart failure

Question 1

The major determinants of variation of cardiac output are:

Answer 1

Heart rate
Myocardial contractility
Preload
Afterload

Question 2

Heart failure

Answer 2

A condition in which the heart fails to maintain a circulation adequate for the body’s needs
Signifies inability of the heart to discharge its contents adequately
Characterised by cardiac dysfunction associated with dyspnoea and/or fatigue

Question 3

Acute heart failure

Answer 3

Sudden circulatory collapse

e.g. haemorrhagic shock, cardiogenic shock during acute MI

Question 4

Chronic (congestive) heart failure

Answer 4

A condition in which the heart fails to maintain a circulation adequate for the body despite adequate venous return
High prevalence
Annual incidence of new diagnoses approximately 3-5 per 1000
Median 5 year mortality is ~50% with an annual mortality of 60% for more severe heart failure

Question 5

Forward HF

Backward HF

Answer 5

Forward HF: predominant problem is reduced output

Backward HF: near normal output but venous congestion

Question 6

Systolic HF

Diastolic HF

Answer 6

Systolic HF: reduced ventricular contractility

Diastolic HF: reduced ventricular filling

Question 7

Low-output HF

High output HF

Answer 7

Low output: implies reduced output

High output HF: high output but still insufficient e.g. in severe anaemia or thyrotoxicosis

Question 8

Compensated HF

Decompensated HF

Answer 8

Compensated HF: stable, adequately controlled symptoms

Decompensated HF: acute overt episode on chronic background (relapsing/ remitting course)

Question 9

Aetiology of CHF

Answer 9

Usually there is some form of cardiomyopathy
Many causes: inherited- congenital hypertrophic CM, arrhythmogenic RV CM
Acquired- ischaemic cardiomyopathy, pressure overload, valvular disease, infection/ inflammation, chronic volume overload

Question 10

Acquired Cardiomyopathies

Answer 10

Ischaemic cardiomyopathy- post myocardial infarction (LV with/without RV)
Increased ventricular afterload- systemic hypertension, pulmonary disease or pulmonary hypertension, aortic valve stenosis, pulmonary valve stenosis
Valvular disease- mitral valve stenosis
Infection/ inflammation- viral/ bacterial myocarditis, alcoholic cardiomyopathy, doxorubicin-induced myocarditis etc.

Question 11

Gradual reduction in cardiac function results in clinical signs/ symptoms

Answer 11

Reduced cardiac contractility
Reduced cardiac output
Reduced tissue perfusion
Reduced venous return and volume expansion
Dyspnoea, fatigue and oedema

Question 12

Oedema in heart failure

Answer 12

A characteristic feature of congestive heart failure: limb extremities especially ankles (pitting oedema), intra-abdominal fluid accumulation (ascites), pulmonary oedema causes crepitations and dyspnoea

Question 13

Neurohormonal response to decreased cardiac output

Answer 13

Primary response to a fall in CO is a Neurohormonal reflex to maintain perfusion of vital organs
In evolutionary terms, it is an ancient conserved neuroendocrine defence reaction to massive blood loss
Major features are: peripheral vasoconstriction, reduced fluid excretion through sympathetic nervous system activation and renin-angiotensin system activation

Question 14

Some neurohormones promote proliferative signalling

Answer 14

Angiotensin II and NAd promote myocyte hypertrophy and fibroblast mitosis
Aldosterone promotes cardiac collagen synthesis