Echocardiography:

An echocardiogram, often referred to in the medical community as a cardiac ECHO or simply an ECHO, is a sonogram of the heart. Also known as a cardiac ultrasound, it uses standard ultrasound techniques to image two-dimensional slices of the heart. The latest ultrasound systems now employ 3D real-time imaging.

In addition to creating two-dimensional pictures of the cardiovascular system, an echocardiogram can also produce accurate assessment of the velocity of blood and cardiac tissue at any arbitrary point using pulsed or continuous wave Doppler ultrasound. This allows assessment of cardiac valve areas and function, any abnormal communications between the left and right side of the heart, any leaking of blood through the valves (valvular regurgitation), and calculation of the cardiac output as well as the ejection fraction.

Echocardiography was an early medical application of ultrasound. Echocardiography was also the first application of intravenous contrast-enhanced ultrasound. This technique injects gas-filled microbubbles into the venous system to improve tissue and blood delineation. Contrast is also currently being evaluated for its effectiveness in evaluating myocardial perfusion. It can also be used with Doppler ultrasound to improve flow-related measurements (see Doppler echocardiography).

Echocardiography is either performed by cardiac sonographers or doctors trained in cardiology.

Purpose:
Echocardiography is used to diagnose cardiovascular diseases. In fact, it is one of the most widely used diagnostic tests for heart disease. It can provide a wealth of helpful information, including the size and shape of the heart, its pumping capacity and the location and extent of any damage to its tissues. It is especially useful for assessing diseases of the heart valves. It not only allows doctors to evaluate the heart valves, but it can detect abnormalities in the pattern of blood flow, such as the backward flow of blood through partly closed heart valves, known as regurgitation. By assessing the motion of the heart wall, echocardiography can help detect the presence and assess the severity of coronary artery disease, as well as help determine whether any chest pain is related to heart disease. Echocardiography can also help detect hypertrophic cardiomyopathy. The biggest advantage to echocardiography is that it is noninvasive (doesn't involve breaking the skin or entering body cavities) and has no known risks or side effects.

Transthoracic echocardiogram:
A standard echocardiogram is also known as a transthoracic echocardiogram (TTE), or cardiac ultrasound. In this case, the echocardiography transducer (or probe) is placed on the chest wall (or thorax) of the subject, and images are taken through the chest wall. This is a non-invasive, highly accurate and quick assessment of the overall health of the heart.

Transoesophageal echocardiogram:
This is an alternative way to perform an echocardiogram. A specialized probe containing an ultrasound transducer at its tip is passed into the patient's oesophagus. This allows image and Doppler evaluation which can be recorded. This is known as a transoesophageal echocardiogram, or TOE (TEE in the United States).

Cardiac cycle:
Cardiac cycle is the term referring to all or any of the events related to the flow or pressure of blood that occurs from the beginning of one heartbeat to the beginning of the next.[1] The frequency of the cardiac cycle is the heart rate. Every single 'beat' of the heart involves five major stages: First, "Late diastole" which is when the semilunar valves close, the Av valves open and the whole heart is relaxed. Second, "Atrial systole" when atria is contracting, AV valves open and blood flows from atrium to the ventricle.

Third, "Isovolumic ventricular contraction" it is when the ventricles begin to contract, AV valves close, as well as the semilunar valves and there is no change in volume. Fourth, "ventricular ejection", Ventricles are empty, they are still contracting and the semilunar valves are open. The fifth stage is: "Isovolumic ventricular relaxation", Pressure decreases, no blood is entering the ventricles, ventricles stop contracting and begin to relax, semilunars are shut because blood in the aorta is pushing them shut.

Throughout the cardiac cycle, the blood pressure increases and decreases. The cardiac cycle is coordinated by a series of electrical impulses that are produced by specialized heart cells found within the sino-atrial node and the atrioventricular node. The cardiac muscle is composed of myocytes which initiate their own contraction without help of external nerves (with the exception of modifying the heart rate due to metabolic demand). Under normal circumstances, each cycle takes approximately one second.