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62 Chapter 2: Cardiovascular system

inadequate cardiac outflow, e.g. valvular regurgitation Table 2.8 NYHA classification of functional severity of

or aortic stenosis. heart failure
cardiac arrhythmias, e.g. atrial fibrillation. NYHA class Classification

inadequate ventricular filling, e.g. constrictive peri-

I No limitations, ordinary activity does not
carditis, cardiac tamponade, tachycardias. result in fatigue or breathlessness
increased demand, e.g. anaemia, thyrotoxicosis, II Slight limitation of physical activity,

Paget’s disease, beriberi. patients are comfortable at rest
III Marked limitation of physical activity,
comfortable at rest but physical activity
Pathophysiology
causes symptoms
The mechanism by which the heart fails to deliver a suf- IV Symptoms present at rest, inability to carry
ficient cardiac output is dependent on the underlying out physical activity without discomfort
cause.
In myocardial dysfunction there is an inability of the
normal compensatory mechanisms to maintain cardiac Left-sided heart failure
output. These mechanisms include Causes include myocardial infarction, systemic hyper-
Frank–Starling mechanism in which increased
tension, aortic stenosis/regurgitation, mitral regurgi-
preloadresultsinanincreaseincontractilityandhence tation, cardiomyopathy.
cardiac output. Symptoms:Fatigue,exertionaldyspnoea,orthopnoea,
myocardial hypertrophy with or without cardiac
paroxysmal nocturnal dyspnoea.
chamber dilatation, which increases the amount of Signs: Late inspiratory fine crepitations at lung bases,
contractile tissue. third heart sound due to rapid ventricular filling and
release of noradrenaline, which increases myocardial
cardiomegaly at a late stage.
contractility and causes peripheral vasoconstriction.
activation of the renin–angiotensin–aldosterone sys-
Right-sided heart failure
tem causes sodium and water retention resulting in Causes include myocardial infarction, chronic lung
increased the blood volume and venous return to the disease (cor pulmonale), pulmonary embolism, pul-
heart (preload). monary hypertension, pulmonary stenosis/regurgi-
Other causes of heart failure including valvular heart tation, tricuspid regurgitation and left-sided heart
disease and cardiac arrhythmias may cause heart failure failure with resultant increase in pulmonary venous
in the absence of myocardial dysfunction, conversely a pressure.
patient may have objective evidence of ventricular dys- Symptoms: Fatigue, breathlessness, anorexia, nausea,
function with no clinical evidence of cardiac failure. ankle swelling.
Chronic pulmonary oedema results from increased Signs:Raisedjugularvenouspressure,livercongestion
left atrial pressure, leading to increased interstitial fluid causing hepatomegaly, pitting oedema of the ankles
accumulation in the lungs and therefore reduced gas ex- (or sacrum if patient is confined to bed).
change, lung compliance and dyspnoea. It can be acutely Congestive cardiac failure is the term for a combination
symptomatic when lying flat (orthopnea) or at night of the above, although it is often arbitrarily used for any
(paroxysmal nocturnal dysnoea) due to redistribution symptomatic heart failure.
of blood volume and resorption of dependent oedema.
Investigations
Clinical features Chest X-ray may show cardiomegaly. Chronic pul-
Clinically it is usual to divide cardiac failure into symp- monary oedema results in dilation of the pulmonary
toms and signs of left and right ventricular failure, al- veins particularly those draining the upper lobes (up-
though it is rare to see isolated right-sided heart failure perlobe vein diversion), pleural effusions and Kerley
except in chronic lung disease. Grading of the severity B lines (engorged pulmonary lymphatics). There may
of symptoms of heart failure is by the New York Heart also be evidence of acute pulmonary oedema with ‘bat
Association (NYHA) classification (see Table 2.8). wing’ alveolar or ground glass shadowing.