It is useful and traditional to divide the symptoms and signs of heart failure into four categories: right or left ventricular failure; each ventricular chamber can then cause symptoms of forward failure (i.e. low output) or backward failure (i.e. reduced venous return and hence congestion). It should be understood, however,
that in the clinical scenario the most common forms of heart failure often show elements of all four categories, albeit to varying degrees. Often one or two symptoms dominate the clinical picture; (1) decreased exercise tolerance and
muscle fatigue (i.e. symptoms of low left ventricular output, which indicates forward failure; (2) breathlessness (dyspnoea) due to pulmonary congestion,
indicating left ventricular backward failure; and (3) ankle oedema(i.e. right ventricular backward failure with increased venous capillary pressure).
However, dyspnoea and pulmonary fluid overload were the predominant symptoms, and the patient was therefore classified for clinical and teaching purposes as having left ventricular backward failure. The symptoms of right ventricular forward failure are indistinguishable from those of left ventricular forward failure. The severity of symptoms has been classified by the New York Heart Association (NYHA).
Class I: minimal
Patients with cardiac disease without limitation of physical activity; ordinary physical activity does not cause undue dyspnoea or fatigue
Class II: mild
Patients with cardiac disease resulting in slight limitation of physical activity; comfortable at rest; ordinary physical activity results in dyspnoea or fatigue
Class III: moderate
Patients with cardiac disease resulting in marked limitation of physical activity; comfortable at rest; less than ordinary physical activity causes dyspnoea or fatigue
Patients with cardiac disease resulting in inability to carry on any physical activity
without discomfort; symptoms of heart failure may be present even at rest; if any physical activity is undertaken, discomfort is increased
It should be noted that there is only a loose correlation between symptoms and ventricular function (i.e. it is common to find patients with severely reduced ventricular function who are almost asymptomatic; on the other hand, less severe forms of ventricular dysfunction may cause severe oedema or breathlessness). The reasons for this discrepancy are unclear. It is a common clinical error to judge prognosis on the basis of left ventricular function alone.
The mechanisms underlying the symptoms of heart failure are explained in more detail below. Fluid retention in the pulmonary and peripheral circulation is easily explained. The failing ventricle builds up a higher end-diastolic pressure
because less blood is ejected; this leads to decreased filling and an increase in venous pressure, which is backwashed into the venous segment of the capillaries.
Less fluid is reabsorbed from the venous segment of the capillaries. Interstitial pressure rises and more fluid is pressed back into the venous segment, until a new equilibrium is achieved characterised by an increase in interstitial fluid. This clinically manifests as peripheral oedema (ankle or sacrum on lying down), pulmonary congestion on chest Xray or as crackles on auscultation. In its severest
form, fluid collection in the pulmonary alveoli leads to pulmonary oedema, a dramatic and acutely lifethreatening state.
Other symptoms of heart failure, such as breathlessness (i.e. dyspnoea) without pulmonary congestion or peripheral muscle fatigue, are more difficult to explain. Central nervous mechanisms are probably responsible for dyspnoea, and histological and biochemical alterations have been found in biopsies from peripheral skeletal muscle in patients with heart failure.
The most common causes of heart failure in clinical practice
Ventricular contractile dysfunction in case of coronary heart disease or cardiomyopathy and interests more the left ventricle than the right.
Increased resistance to contraction and cardiac output
Hypertension , Aortic valve stenosis, Coarctation of the aorta – interest the left ventricle
Pulmonary hypertension , Pulmonary valve stenosis – interest the right ventricle instead.
Cardiac dysrhythmias like the atrial fibrillation affecting the right ventricle
Inadequate cardiac filling in the constrictive pericarditis affecting the left ventricle.
Forward failure (= low output) in the right ventricle and left ventricle – fatigue, weakness, cyanosis, peripheral vasoconstriction, nocturia
Backward failure in the right ventricle- ankle oedema, ascites, liver ↑, JVP ↑(jugular venous pressure), pleural or pericardial effusion.
and left ventricle – pulmonary congestion, dyspnoea, cough, pleural or pericardial effusion