What exactly is echocardiogram? What are the doctors measuring when they perform ecg?

Ultrasound of heart. Echocardiogram is essentially an ultrasound of the heart ... Ecg helps measure your heart rhythm and how the electrical impulses in your heart move from the atria to the ventricles ... The latter can show how quickly the impulse moves in different parts of the heart, and can show if a part of the heart is not getting enough oxygenated blood flow, which may warn of a heart attack ...
Heart function. Echocardiogram & EKG (ECG) are 2 completely different things. An echo is an ultrasound - it displays a picture of the structure of the heart, its movement, pressures, and blood flow trajectory. This helps your doctor determine any anatomic or functional problems with the heart. An EKG measures the electrical voltages of the heart. This provides info on possible heart problems.