The inability of the heart to generate enough cardiac output to meet the body's demands.  This could be casued by:

+ Increase workload on an otherwise normal myocardium:  - Increase blood volume such as with anemia.  - Left to right shunting of blood, such as with AV festula or septal defects (ASD, VSD, PDA and AVC defect).  This will cause already oxygenated blood in the left heart to return to the right heart.  The result is decrease in the left ventricular cardiac output and increase in the right ventricle cardiac output.  The decrease cardiac output from the left ventricle will cause poor blood supply to the body, while the increase cardiac output from the right ventricle will cause work overload of the right ventricular myocardium.  An expanded right ventricle will also cause abnormal leftward deviation of the ventricular septum (flattening) resulting in abnormal left ventricular contour and further reduction of ejection capabilities.  - Valvar regurgitation, causing volume overload of the ventricle.	Normal blood flow, normal cardiac chambers Increase blood volume resulting in dilation of cardiac chambers and overload of myocardium.
+ Pressure overload of one or both ventricles, such as with valvular diseases (pulomanry or artic stenoses), coarctation of the aorta, pulmonary vascular obstructive disease or systemic hypertension.
+ Cardiac myocardial disease such as with myocarditis and cardiomyopathy.
+ Coronary arterial insufficiency, such as with Kawaski disease and hyperlipdemia.
+ Abnormal heart rhythm, typically tachycardia. Rapid heart rate will prevent proper filling of the ventricles as it shortens diastole, thus reducing cardiac outpuut.

Regardless of the cause, children and particularly infants will be short of breath, feed poorly and fail to thrive.  With exertion, such as suckling, they will become pale and sweat profusely.  The heart will eventually dilate and the elevated LV and RV end-diastolic pressures will cause pulmonary edema and hepatomegaly respectively.  Pulmonary edema will result in tachypnea, while GI edema will lead to worsening absorbtion and further failure to thrive.

Inspection:  Pallor, respiratory distress, elevated JVP (not possible to assess in infants & young children).
Palpation:  edema, poor capillary refill, poor pulses, hepatomegaly, cardiomegaly, increase RV and/or LV impulses.
Auscultation: gallop rhythm, murmur if associated with CHD or AV valve insufficiency due to ventricular dilation. 

First, attention should be directed to cause and if possible treated.

Supportive therapy: