Failure in a particular chamber of the heart tends to cause a backup of blood in the lungs, known as pulmonary congestive heart failure. Failure of which chamber of the heart would lead to such a backup?

Answer is left ventricle.

Explanation:

The left ventricle is known to be one of the heart's chamber, which is responsible for pumping oxygenated blood to all parts of the body.

The left ventricle failure is caused by the narrowing of the coronary artery, and this can cause a backup of blood in the lungs.

This act will or can cause heart failure.

It should be noted that, heart failure means that the heart can't pump enough blood to meet the requirement of the body.