Echocardiography

Abstract

Echocardiography (Echo) is now firmly established as the single most useful diagnostic test for the evaluation of patients with cardiovascular diseases because it provides reliable structure, functional, and hemodynamic information about the cardiovascular system. Echo utilizes many physical principles of ultrasound in order to derive the diagnostic information obtained. Reflected ultrasound using A-mode (Amplitude) and B-mode (Brightness) ultrasonic signals were the initial means by which Echo was utilized. The dimension of time was introduced with M-mode (Motion) ultrasonography. Doppler techniques for recording intracardiac blood flow were then later developed, Color, Pulse and Continuous wave Doppler. Color Doppler is recorded in real time simultaneous with the 2D imaging. Color Doppler is used to rapidly interrogate large areas of flow such as with mitral regurgitation (Fig. 19.1). Pulse Wave (PW) allows measurement of blood flow velocities at a specific intra cardiac site. PW is beneficial in the hemodynamic characterization of blood flow in any specific location in which peak velocity does not exceed the Nyquist limit/aliasing, such as with the MV inflow to assess diastolic function. Continuous wave (CW) records signals along the entire length of the ultrasound image of interest. CW is utilized to measure maximum/peak velocities and pressure gradients across the cardiac valves and intra cardiac shunts and obstructions.