Investigations

The initial evaluation of new onset heart failure should include an electrocardiogram, chest radiograph, and B-type natriuretic peptide assay. The cardiac rhythm may be normal sinus, sinus tachycardia, or atrial fibrillation. Left ventricular hypertrophy, left bundle branch block,intraventricular conduction delay, and non-specific ST segment and T wave changes support a diagnosis of heart failure. Q waves in contiguous leads strongly implicate a previous myocardial infarction and coronary atherosclerosis as the etiology. Chest radiographic findings of heart failure include cardiomegaly, pulmonary vascular redistribution, pulmonary venous congestion,Kerley B lines, alveolar edema, and pleural effusions.

Chest X-ray

Increase in cardio-thoracic ratio is a relatively specific indicator of left ventricular end-diastolic volume. Left atrial enlargement is seen as double density shadow, lifting up of the left main bronchus and left atrial appendage enlargement.When pulmonary venous pressure rises to 12 to 18 mmHg, pulmonary blood flow is redirected to upper lobes in the erect position. Thus prominent upper lobar veins indicate pulmonary venous hypertension (“cephalisation”).

With pressure above 18 mmHg, interstitial edema develops. Kerley B lines are seen in interstitial pulmonary edema. Kerley B lines are interlobular septal lines and are seen as thin horizontal lines at both lung bases perpendicular to the lateral pleural surface.
 

When the pulmonary venous pressure exceeds 25 mmHg, alveolar edema occurs. Acute pulmonary edema produces “butterfly” or “bat wing” pattern in the chest X-ray seen in the inner two thirds of the lung. The outer third of the lung has better ventilation, better pumping action during respiration, better compliance and better lymphatic drainage.

Onset of pulmonary arterial hypertension leads to prominent central vessels with peripheral pruning (“Centralisation”).

ECG

Sinus tachycardia is common. ECG abnormalities may reflect the underlying coronary artery disease by way of pathological Q-waves, ST-T wave abnormalities. Left ventricular hypertrophy and left atrial enlargement show changes on ECG.

Atrial fibrillation with rapid ventricular rate may act as a precipitating factor for the heart failure or it may occur due to the underlying dilated cardiomyopathy. Ventricular ectopics are common in heart failure and may indicate adverse prognosis.

Left bundle branch block (LBBB) is usually associated with underlying heart disease. LBBB in coronary artery disease indicates severe disease, poor left ventricular function and decreased survival.

Echocardiography
Both global and regional systolic function are to be checked. Global measures include ejection fraction, stroke volume, end systolic volume. (For measurement of systolic function using M-mode and 2D echocardiography refer to the section on Echocardiography.)

In diastolic dysfunction there is generally presence of left ventricular hypertrophy. The transmitral flow is studied by pulsed Doppler. In normals the early filling velocity (E-wave) is larger than the velocity during atrial contraction (A-wave) and the descent is fast. In diastolic dysfunction there are in general 2 types of patterns. When relaxation is impaired the E-wave becomes smaller and its deceleration time is prolonged and the A-wave becomes taller. With restrictive physiology the E-wave becomes taller and the deceleration time is shorter and the A-wave is smaller. There are also abnormalities in the pulmonary venous flow patterns.

Laboratory Tests
Routine blood tests like haemoglobin, creatinine, electrolytes are useful to plan treatment. More recently the blood natriuretic peptide levels have been used to assess heart failure. BNP (brain natriuretic peptide) may be increased early in left ventricular dysfunction. It is synthesized mainly by the ventricles and released early in heart failure.

The Framingham study group has come out with criteria for diagnosis of heart failure incorporating symptoms, signs, investigations and response to treatment. It is a useful criteria for the clinicians. 

Major Criteria

Paroxysmal nocturnal dyspnoea

neck vein distention

Rales

Radiographic cardiomegaly

Acute pulmonary edema

S 3 gallop

Central venous pressure >16 cm H 2 O

Circulation time >25 sec

Hepatojugular reflux

Pulmonary adema, visceral congestion, or cardiomegaly at autopsy

Weight loss >4.5 kg in 5 days in response to treatment of congestive heart failure.

Minor Major
Bilateral ankle edema

Nocturnal cough

Dyspnoea on ordinary exertion

Hepatomegaly

Pleural effusion

Decrease in vital capacity by one third from maximal value recorded

Tachycardia (rate >120 beats/min)

Note: The diagnosis of congestive heart failure in this study required that two majoror one major and two minor criteria be present concurrently. Minor criteria were acceptable only if they could not be attributed to another medical condition.

Source: Ho, K.L., Pinsky, J.L., Kannel, W.B., Levy, D. “The Epidemiology of Heart Failure:The Framingham Study”, J Am Coll Cardiol 22, (Suppl A): 6A, 1993.