Basics of Transthoracic Echocardiogram

Basics of Transthoracic Echocardiogram1 March 2013PGI Chandigarh Dr Sarvesh Natani

SONAR( sound navigation & ranging) in 1800sIngle Edler& Carl Hertz 1st recorded echo 1950 in swedenCW 1963Real time scanner 1965PW 19701974 1st duplex pulse doppler scanner1980 color doppler.History

Wave PropertyFrequency (f) & wavelength ()Propogation speed 1540m/s20- 20000 Hz1-10 million ( 1- 10 MHz) in echoUpto 30 MHz for intracoronary imagingShorter higher f better resolution reduced penetration

Basic Physics

B mode or basic grey scalePresets for echo automatically default to higher frame ratesDepth: start deep then decrease n focus on area of importance. try to get area of intrest in upper 2/3Gain: How machine listens to returning echoes. gain amplifies returning echo n image is brighter.Can be over all or at depth called TGC.

Knobology

ZoomFocus : optimises lateral resolution at given depthTissue Hamonics; Frame rate etc

KnobologyM mode: visualize moving thing in 1 dimension eg IVC, cardiac valves.Doppler: uses frequency shift of sound waves to measure velocityColor flowPulse waveContinuous wave Other ModesTran thoracic EchoA standard echocardiogram is also known as a Trans thoracic echocardiogram (TTE), or cardiac ultrasound. The subject is asked to lie in the semi recumbent position on his or her left side with the head elevated.The left arm is tucked under the head and the right arm lies along the right side of the bodyStandard positions on the chest wall are used for placement of the transducer called echo windows

19Described by size n shape of footprint.Linear, curvilinear and phased array Phased array probe ;an electronically steered beam in a close array, generating an image that comes from a point and is good for getting between ribs such as in cardiac ultrasound. F 1-10MHz

Probe/ transducerRight probe selection is very imp.Linear high frequency for sup str like vascularCuvilinear wider footprint low freq deeper penetration.20Echo ProbeImaging requires the use of intercostal acoustic windows.Probes with small footprints.Phased or microconvex arrays are utilized for this reason.Imaging in adults; lower frequencies (typically 2-4 MHz).Curvilinear probes can be used to image the heart, especially in the subxiphoidview.However,

ParasternalApicalSubcoastalSuprasternal

Echo WindowsTranslationRotationAngulationHeal- toeProbe MovementsParasternal Long-Axis View (PLAX)

Transducer position: left sternal edge; 2nd 4th intercostal spaceMarker dot direction: points towards right shoulderMost echo studies begin with this viewIt sets the stage for subsequent echo viewsMany structures seen from this view

SV= * (LVOT2)2* VTI1LVEDV=(7 *LVEDD3)/(2.4 + LVEDD)LVEF=SV/LVEDV30

Parasternal Short Axis View (PSAX)Transducer position: left sternal edge; 2nd 4th intercostal spaceMarker dot direction: points towards left shoulder(900 clockwise from PLAX view)By tilting transducer on an axis between the left hip and right shoulder, short axis views are obtained at different levels, from the aorta to the LV apex.Many structures seen

Intra atrial septumTVPV39