TRANS ESOPHAGEAL ECHOCARDIOGRAPHY

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Discuss the role of TEE in the perioperative management of patients undergoing cardiac surgery.

Transcript of TRANS ESOPHAGEAL ECHOCARDIOGRAPHY

  • 1.

2. POWERFUL DIAGNOSTIC TOOL DECREASE MORBIDITY INCREASE SURVIVAL 3. ANESTHETISED PATIENTS PHYSIOLOGY IS DIFFERENT; WE KNOW IT BETTER! WE ARE CLOSELY LINKED WITH THE PERIOPERATIVE CARE 4. LUNGS AND RIBS DONT INTERFERE ONLY ESOPHAGEAL WALL AND PERICARDIUM IN BETWEEN WONT DISRUPT SURGERY TRANS THORACIC IS DIFFICULT IN:OBESITY/EMPHYSEMA/ABNORMAL CHEST WALL 5. 6. 7. 8.

  • tissue insonated with sound above audible range, >20000 Hz
  • Most use 2.5-7.5 Hz
  • Transducer composed of piezoelectric crystals

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  • Electrical signal applied to the crystalvibrate sound absorption/reflection/refraction/scattering reflected ultrasound wave crystal receive the reflected waveconvert it back to electrical signal

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  • v =f x
  • Ultrasound travels at 1540 m/sec
  • Hence v constant
  • As f increase,decrease
  • v,f andknown
  • Time find out
  • Hence depth find out

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  • F more absorption moreresolution more
  • less attenuation morepenetration less

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  • Water, muscle, bloodless impedanceless attenuation
  • Air , bonehigh impedanceultrasound traverse poorly

13. DOPPLER PRINCIPLE: WHEN A WAVE OF A GIVEN FREQUENCY,STRIKES A MOVING TARGET,IT WILL BE REFLECTED AND THE REFLECTED WAVE WILL SHOW A FREQUENCY SHIFT PROPORTIONAL TO THE VELOCITY OF THE TARGET WHICH IS PARALLEL TO THE PATH OF THE EMITTED WAVE 14.

  • If target is moving away from the emitted wave, the frequency of the reflected wave will be lower
  • If the target is moving towards the transducer, the frequency of the reflected wave will be higher

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  • RBCs act as excellent reflectors
  • Measuring the RBC flow velocity in the heart is the application used here
  • accurate when the transmitted beam and the velocity vector are parallel [ at least within 20]

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  • .

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  • Most basic mode
  • Waves transmitted as a single beam
  • Only tissues which come in this narrow path are displayed
  • Only a limited area is visualized
  • Waves transmitted and received back in 0.001 sec

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  • So 1000 frames/sec = REAL TIME
  • High resolution : even subtle changes in motion/dimension are well picked
  • Hence finer analysis best done with this mode

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  • Amplitude of returning waves are displayed as shades of brightness
  • Blood filled chambers no reflected waves BLACK
  • Valve tissue and myocardiumhigh reflected wave activity grey/white
  • ..pdfnotesPocket Atlas of Echocardiography.pdf

23. 24.

  • Obtained by rapid repetitive scanning along multiple beam lines within an area in the shape of a fan (sector), 60-90wide
  • Done by phased array technology
  • Sector contains approx. 100 scan lines time consuming
  • Information updated 30-60 times

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  • Desired view is obtained by 2D echoDoppler beam superimposed
  • Cursor is positioned as parallel as possible to the assumed direction of blood flow
  • Quantify stenosis , regurgitation
  • Demonstrate shunts
  • ..videosvideo.flv

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  • PULSED WAVE DOPPLER
  • CONTINUOUS WAVE DOPPLER
  • COLOR FLOW DOPPLER

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  • a single crystal intermittently transmits and receives ultra sound signalsanalyzed for frequency shifts
  • Cursor placed on an updated 2D image and reflected wave from only that portion analyzed

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  • We can contract or expand the interrogated area
  • Problem : there is a velocity limit (.8-1 m/sec) for the wave, beyond which a phenomenon known as aliasing or wraparound occursambiguous velocity and time information

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  • Allows a flow disturbance to be localized precisely or blood velocity from a small region to be measured correctly
  • e.g. mitral inflow, tricuspid inflow

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  • One transducer continuously emit signals
  • Another one continuously receive reflected signals
  • Very high velocities can be reliably detected
  • Since no lag between
  • emission and reception

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  • i.e. extremely high sampling frequencyminimize aliasing
  • problem : reflected signals returning from all points are analyzed.. Cant localize a signal precisely

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  • Useful for: measuring high velocities e.g. intracardiac shunts , regurgitant jet, flow across stenotic valves like AS
  • Velocities up to 600-800 cm/ sec can be measured

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  • Uses pulsed wave technology to measure blood flow at multiple sites
  • Real time blood flow is shown in colors
  • While also showing 2D images in black and white

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  • Velocities and directions of blood flow are color encoded
  • Velocity awayblue
  • Velocity towardsredBART
  • High turbulencegreen
  • As velocity increase intensity of color also increase

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  • Aliasing occurscolor mosaic
  • But as 2D image is there, direction of this aliased signal can be determined easily
  • Assess valvular
  • abnormalities , shunts, aortic dissection

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  • Transducer fitted to the distal, flexible end of a gastroscope
  • Adult : above 20-25 Kg
  • Pediatric : above 3.5- 4 Kg
  • Adult @ 5 MHz Pediatric @7.5 MHz
  • 2DM-modePWDCWD--COLOR

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  • Two rotary knobs
  • One for anteflexion and retroflexion
  • One for rightward and leftward flexion

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  • Can rotate the angle plane without movement of the probe
  • Good view of LA,MV..
  • ..pdfnotesiadt07i4p324.pdf

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  • ADVANCED/WITHDRAWN
  • RIGHT/LEFT
  • ANTEFLEXED/RETROFLEXED-90
  • LATERAL FLEXION-70

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  • Single plane0
  • Biplane one transducer: 0
  • one transducer 90
  • Multiplane probes0-180

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  • HISTORY: dysphagia/ hemetemesis/ previous surgeries on GIT/ cervical spine disease
  • Fasting for 4-6 hrs
  • Remove dentures
  • Airway/ oxygen delivery systems / bite block/ suction / intubation cart / IVA

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  • TOPICAL : lignocaine
  • SEDATION
  • ANTIXYLAGOGUE

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  • Orogastric tube
  • Supine / left lateral
  • Operator stands as in for Lscopy
  • ETT secured
  • Probe in unlocked positionalign with natural anatomy
  • Lubricated
  • Bite block on probe

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  • Thumb of left hand placed on patients tongue
  • Left hand used to pull jaw upward
  • Pass probe tip through bite guard , over tongue , maintaining it in midline ( transducer facing anteriorly) and to the left of ETT

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  • Mild resistance felt @ pharyngo esophageal junction [ neonate: 10 cm from lip, adult : 20 cms]
  • If doubt : done under laryngoscopy
  • no hot water1-2 hrs
  • Not to eat1-4 hrs

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  • Inspected for defects
  • Enzymatic solution to remove secretions
  • Gluteraldehyde for 20 mins
  • Tap water dry for 20 mins

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  • Apex of the sector scan is shown at the top of the echo screen which displays posterior parts of the heart ( part close to probe)

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  • In the transverse imaging plane, left of image is towards patients right and right of the image is towards patients left

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  • In the vertical imaging plane, left side of the image is inferior and point towards patients feet
  • Right side of the image is anterior and points towards patients head
  • ..pdfnotesiadt07i4p324.pdf

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  • Once we centre a cardiac structure in one image plane,it will continue to remain there as the transducer is rotated from 0-180,facilitating the 3D assessment of that particular structure

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  • Markedly abnormal ventricular function
  • Extensive MI
  • Large air emboli
  • Severe valvular dysfunction
  • Large mass or thrombi
  • Large effusion
  • Major lesions of great vessels

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  • 20 viewscomprehensive examination
  • 8 out of 20 needed to meet these goals

65.

  • Upper esophageal(20-30 cm)
  • Mid esophageal(30-40 cm)
  • Transgastric (40-45 cm)