Echocardiography can also identify valvular heart disease and assess the state of the pericardium (the connective tissue sac surrounding the heart). Echocardiography may also aid in deciding specific treatments, such as medication, insertion of an implantable cardioverter-defibrillator, or cardiac resynchronization therapy. Echocardiography can also help determine if acute myocardial ischemia is the precipitating cause, and may manifest as regional wall motion abnormalities on echo. Chest X-ray
Chest X-rays are frequently used to aid in the diagnosis of CHF. In a person who is compensated, this may show cardiomegaly (visible enlargement of the heart), quantified as the cardiothoracic ratio (proportion of the heart size to the chest). In left ventricular failure, evidence may exist of vascular redistribution (upper lobe blood diversion or cephalization), Kerley lines, cuffing of the areas around the bronchi, and interstitial edema. Ultrasound of the lung may also be able to detect Kerley lines. Electrophysiology
An electrocardiogram (ECG/EKG) may be used to identify arrhythmias, ischemic heart disease, right and left ventricular hypertrophy, and presence of conduction delay or abnormalities (e.g. left bundle branch block). Although these findings are not specific to the diagnosis of heart failure, a normal ECG virtually excludes left ventricular systolic dysfunction. Blood tests
Blood tests routinely performed include electrolytes (sodium, potassium), measures of kidney function, liver function tests, thyroid function tests, a complete blood count, and often C-reactive protein if infection is suspected. An elevated brain natriuretic peptide 32 (BNP) is a specific test indicative of heart failure.
Over time, these increases in workload, which are mediated by long-term activation of neurohormonal systems such as the renin–angiotensin system and the sympathoadrenal system, lead to fibrosis, dilation, and structural changes in the shape of the left ventricle from elliptical to spherical.The heart of a person with heart failure may have a reduced force of contraction due to overloading of the ventricle. In a normal heart, increased filling of the ventricle results in increased contraction force by the Frank–Starling law of the heart, and thus a rise in cardiac output. In heart failure, this mechanism fails, as the ventricle is loaded with blood to the point where heart muscle contraction becomes less efficient. This is due to reduced ability to cross-link actin and myosin myofilaments in over-stretched heart muscle. Diagnosis
No diagnostic criteria have been agreed on as the gold standard for heart failure. In the UK the National Institute for Health and Care Excellence recommends measuring brain natriuretic peptide 32 (BNP) followed by an ultrasound of the heart if positive. This is recommended in those with shortness of breath. In those with worsening heart failure, both a measure of BNP and of troponin are recommended to help determine likely outcomes. Classification
One historical method of categorizing heart failure is by the side of the heart involved (left heart failure versus right heart failure).