What is Echocardiography?

Echocardiography is another form of ultrasound imaging. It allows the structures of the heart to be visualised. The imaging is done by a probe placed on the chest well. The two dimensional echocardiography (Trans Thoracic Echo or TTE) provides sections of the structures and chambers of the heart. Serial images may be combined to give a real time view.

Doppler Echocardiography is based on Doppler principle sound waves reflected from moving objects sustain a change in frequency. By detecting the speed and direction of red blood cells, we can accurately calculate the properties of blood flow. The information obtained may be converted to colour patterns to indicate velocity and direction of blood flow. This gives accurate measurement of valve leaks. Two dimensional echo combined with Doppler is a simple non-invasive and reliable method of assessing structure and function of heart.

What is the difference between ICU and CCU in the hospital?

ICU stands for "Intensive Care Unit."  It is a generic term for a unit that provides critical care and monitoring to patients with non-specific disease entities. Some smaller hospitals may have only one critical care unit, that takes all types of sick adult patients, but most hospitals of any size now have specialty critical care units:
CCU: Coronary (or cardiac) Intensive Care Unit that takes patients who have cardiac-related problems (usually non-surgical).
SICU: Surgical Intensive Care Unit that takes seriously ill patients who have had surgery (including heart surgery).
MICU: Medical Intensive Care Unit that cares for seriously ill patients suffering from non-cardiac medical problems.
Larger teaching hospitals might have several other specialty ICUs such as Neonatal, Respiratory, Pediatric, Neuro, etc.