ESSENTIAL ECHOCARDIOGRAPHY A Companion to Braunwald’s Heart Disease 2019 PDF

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ESSENTIAL ECHOCARDIOGRAPHY A Companion to Braunwald’s Heart Disease 2019 PDF

ESSENTIAL ECHOCARDIOGRAPHY A Companion to Braunwald’s Heart Disease 2019 PDF

ESSENTIAL ECHOCARDIOGRAPHY A Companion to Braunwald’s Heart Disease 2019 PDF Ultrasound imaging is ubiquitous in medical practice and is used to image all regions of the body, including soft tissues, blood vessels, and muscles. The machines used for ultrasound imaging range from small hand-held ultrasound devices no bigger than a smartphone to more elaborate and complex systems capable of advanced imaging techniques such as threedimensional (3D) imaging. Although imaging of the heart and great vessels has traditionally been referred to as “echocardiography,” the fundamental physical principles of image generation are common to all ultrasound devices. These principles should be familiar to the end-user because they are essential to understanding the utility and limitations of ultrasound and to the interpretation of ultrasound images and can help optimize the use of ultrasound systems to obtain the highest-quality images.

The generation of images by ultrasound is based on the pulse-echo principle.1-3 It is initiated by an electric pulse that leads to the deformation of a piezoelectric crystal housed in a transducer. This deformation results in a high-frequency (>1,000,000 Hz) sound wave (ultrasound), which can propagate through a tissue when the transducer is applied, resulting in an  acoustic compression wave that will propagate away from the crystal through the soft tissue at a speed of approximately 1530 m/s. As with all sound waves, each compression is succeeded by decompression: the rate of these events defines the frequency of the wave. In diagnostic ultrasound imaging, this applied frequency is generally between 2.5 and 10 MHz, which is far beyond the level audible by humans, and is thus termed ultrasound.
The principal determinants of the ultrasound wave are: (1) wavelength (λ), which represents the spatial distance between two compressions (and is the primary determinant of axial resolution, as defined later), (2)
frequency (f), which is inversely related to wavelength, and (3) velocity of sound (c), which is a constant for any given medium

These three wave characteristics have a set relationship as c = λf. An increase in the frequency (i.e., shortening of the wavelength) implies less deep penetration due to greater viscous effects leading to more attenuation.

ESSENTIAL ECHOCARDIOGRAPHY A Companion to Braunwald’s Heart Disease 2019 PDF

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