Mod1: Monitoring for Cardiac Surgery - TEE Flashcards
THE BASICS OF TRANSESOPHAGEAL ECHOCARDIOGRAPHY
When was TEE first used and what were its limitations?
The first use of TEE was in 1975
Had a very limited range and very little ability to change the angle of the view
THE BASICS OF TRANSESOPHAGEAL ECHOCARDIOGRAPH
Which factors have contributed to the improvement of the quality and utility of today’s TEE’s and have expanded its use 100 fold?
Provision of multiple planes of view
Multiple frequency of probes
Color flow mapping
Pulse and continuous wave Doppler
Digital image processing
THE BASICS OF TRANSESOPHAGEAL ECHOCARDIOGRAPH
In 2010, the ASA approved updates to guidelines which states that “the TEE should be used in which surgical procedures?
all open heart and thoracic or aortic surgical procedures and should be considered in CABG surgeries
THE BASICS OF TRANSESOPHAGEAL ECHOCARDIOGRAPH
In 2010, the ASA approved updates to guidelines which states that “the TEE should be used in all open heart and thoracic or aortic surgical procedures and should be considered in CABG surgeries for what purpose?
To confirm and refine the preop diagnosis
To detect new and unsuspected pathologies
To adjust the anesthetic and surgical plan accordingly
To assess the results of surgical intervention
TEE COMMON INDICATIONS
According to ASA TEE Guidelines, the TEE can be used by providers in which two ways?
Basic Perioperative TEE
Advanced Perioperative TEE
TEE COMMON INDICATIONS
What’s an advantage of the Basic Perioperative TEE over the PA catheter as a periop measure the determine a pt’s instability?
Previously, the PA catheter was used to determine why pt a may be hempdynamically unstable
Now the provider is able to used the TEE to determine the primary source of the pt’s instability
TEE COMMON INDICATIONS
What’s the major added benefit of the Advanced Perioperative TEE over the Basic Perioperative TEE?
The anesthesiologist performing the TEE can make therapeutic and surgical recommendations based upon their TEE interpretation
TEE COMMON INDICATIONS
What’s required from the provider to used the Advanced Perioperative TEE?
Requires Training and certification at all levels of perioperative echocardiography reading
It also may require additional credentialing at the practicing institution
TEE COMMON INDICATIONS
The TEE can guide the evaluation and treatment of which heart valve abnormalities?
Assessment of valvular function both intra and postop
Evaluation of valvular repairs and prosthetic valve surgery
Assessment of the aorta for arteriosclerosis, calcification and dissections
TEE COMMON INDICATIONS
When is it important to Assessment of the aorta for arteriosclerosis, calcification and dissections via TEE?
Before the aorta is clamped, and
Prior to coming off bypass
TEE COMMON INDICATIONS
What are other common indications for TEE?
Assessment of Global LVF and regional wall motion abnormalities (RWMA)
Detection of cardiac defects, masses, and vegetation
To see optimal de-airing after open heart surgery
For quick evaluation of severe hypotension intra and postop by ruling out conditions like cardiac tamponade, poor LV volume status, RWMA, malfunction of prosthetic valves, or aortic dissection
Inadequate or impossible transthoracic echocardiography
TEE IN NON-CARDIAC SURGERY
T/F: Although TEE is a fast and relatively non-invasive technique, its routine use for NON-cardiac surgery is yet to be established
True
Studies showing the routine use, though, of TEE in non-cardiac surgeries as a benefit are limited in number and equivocal in outcome
TEE IN NON-CARDIAC SURGERY
T/F: Many studies have revealed that TEE is more sensitive than EKG for EARLY detection of ischemia
True
TEE IN NON-CARDIAC SURGERY
When is TEE indicated in non cardiac surgery?
In situations where it is used to explain life threatening circulatory instability that persist despite corrective therapy
PROPERTIES OF ULTRASOUND
How does the TEE ultrsound probe work?
Ultrasound machines generate vibrations that vibrate surrounding tissue (muscle, blood, fat, or bone)
During the vibration, particles within the tissue compress, then spread apart, also known as compression and rarefaction
This sequence of compression and rarefaction is described using sine waves and characterized by:
Wavelength - Frequency - Amplitude - Propagation velocity
PROPERTIES OF ULTRASOUND
It is the distance b/t two peaks of the sine wave
It’s measured in millimeters
What is Wavelength?
PROPERTIES OF ULTRASOUND
Is the number of cycles that occur in one second
1 cycle/second = 1 hertz (Hz)
What is Frequency?
PROPERTIES OF ULTRASOUND
Ultrasound frenquency travel much higher than what is audible with the human ear. Which frequency can the human ear typically hear?
Between 2000 to 5000 Hz
Some experience show that we can hear up to 20,000Hz
PROPERTIES OF ULTRASOUND
Which US frequency do TEE uses?
Frequencies above 20,000Hz
TEE uses frequencies of 2.5-7.5 million cycles per seconds (MHz)
PROPERTIES OF ULTRASOUND
What does amplitude measure?
Amplitude measures of tissue compression or “loudness” of tissue
PROPERTIES OF ULTRASOUND
What is Propagation velocity?
The speed of an ultrasound wave traveling through tissue
Depends on the tissue
PROPERTIES OF ULTRASOUND
What’s the ultrasound Propagation velocity in blood?
1540 meters per second (m/s)
BASICS OF TEE
How does the TEE probe generate US waves?
Echo probe has piezoelectrode in it that can convert electrical activity delivered to it into ultrasound wave
A piezoelectrode in the probe converts electrical energy delivered to the probe into ultrasound waves
BASICS OF TEE
Echocardiography uses ultrasound waves with frequencies of:
2.5 to 7.5 million cycles per seconds (MHz)
BASICS OF TEE
What’s the relationship between US frequency, depth of penetration, and resolution?
The slower the frequency, the greater the depth of penetration but produces poor resolution
The faster the frequency, the greater the resolution, but penetration becomes poor
BASICS OF TEE
Why are frequencies greater than 7.5 MHz are not used?
d/t poor penetration
BASICS OF TEE
Why are frequencies less than 2.5 produce wavelengths not used?
too long for resolution of small objects
BASICS OF TEE
With TEE and cardiac procedures, which TEE technique do providers use to examine the function of the heart?
Doppler Technique
Assesses blood flow through heart chambers and valves
Assess LV function, chamber size, wall size and motion
Valve patency
Abnormal flow, structures, plaque, air, or vegetation
BASICS OF TEE
What equation does the Doppler effect used the determine pressure gradient between areas of different velocity?
Bernoulli equation
Except for in the fetal heart, the volume of blood flowing through the heart must always be the same as the volume of blood that passes through the aortic valve
When the pathway through which blood flows becomes too narrow, the blood velocity must increase to pass the volume
Providers can read this velocity as it moves pass the ech probe using the Bernoulli equation
The doppler principle creates a visual picture of the heart blood flow by assessing the color codes of the velocities in the heart
BASICS OF TEE
Based on the doppler effect, what’s the color difference between blood flow directed towards the probe and blood flow going away from the probe? What is turbulent flow?
Blood flow that is directed towards the probe is red
Blood flow going away from the probe is blue
The higher the velocity of the flow, the lighter the color hues, and this is called turbulent flow
BASICS OF TEE
What’s the first mode that echocardiograms were able to reproduce?
M-Mode
Still used today
One dimensional, or Ice pick view
Single, narrow line of sight
BASICS OF TEE
What are applications of the M-mode?
Used today to view rapidly moving structures, such as valve leaflets
Used to measure heart chambers, size of heart, and thickness of heart walls
BASICS OF TEE
What’s a major drawback of the M-mode?
Only reveals a small portion of the heart at one time, which makes orientation and interpretation of special relationships difficult
BASICS OF TEE
Which mode was created to redirect the ultrasound beam over areas of interest, with the advantage that it could recognize anatomical and pathological landmarks
2-D Echo
Sweeps US beam across a plane
Provides views of structures and motion
BASICS OF TEE
T/F: Images from 2-D Echo are displayed in real time and can be recorded
True
This allows the provider to view the structures at work, while also being able to record and view them later
BASICS OF TEE
What are the 3 types of 2-D Echo?
Pulsed Wave doppler
Continuous Wave
Color Doppler
BASICS OF TEE
Which type of 2-D Echo measures velocity and direction of blood flow using single transducer
Pulsed Wave doppler
The operator can define a small area anywhere in the 2-D area which will display in real time blood flow velocity
(left image)
The beam must hit the target and travel back to the probe for interpretation
BASICS OF TEE
Which type of 2-D Echo uses two transducers?
Continuous Wave Doppler
One transducer emits the ultrasound wave continuosly
The other transducer receives the ultrasound wave continuously
(Right image)
The ultrasound wave continiously move back and forth
BASICS OF TEE
Why is it that the provider cannot precisely define the location of the moving target using the Continuous Wave Doppler 2-D Echo?
Since the Continuous Wave Doppler 2-D Echo has two transducers (One that emits the ultrasound wave continuosly, while the other receives the ultrasound wave continuously) high veolcity can be read, but unfortunately depth from the transducer cannot be read
BASICS OF TEE
Which type of 2-D Echo is an enhanced form of continuous wave Doppler that displays real time blood flow in the heart over the 2-D image
Color Doppler 2-D Echo
Displays real time blood flow in the heart over the 2-D image, and this is how direction of flow is determined
BASICS OF TEE
What’s the newest TEE technology?
What are its advantages over the older technology?
3-D Echo is the newest technology
An array of transducers are used to reconstruct the heart in 3-D image
Allows for better visualization of heat structures (valves, regurgitant valvular lesions, cardiac chamber volumes, 3-D stress imaging)
BASICS OF TEE
According to the Transesophageal Echocardiography Practice Guidelines, what are the two levels of TEE practice?
Basic and advanced
BASICS OF TEE
According to the Transesophageal Echocardiography Practice Guidelines which level of training are providers required to acheive?
What minimum number of superivised TEE are they required to perform and interpret?
Providers are required to attain at least an intermediate level of training in echocardiography and to perform and interpret at least 50 supervised TEE examinations
BASICS OF TEE
On which prior recommendations are Transesophageal Echocardiography Practice Guidelines based?
On the prior recommendations for TransThoracic Echocardiography and are directed at training for TEE in both operative and non-operative application
BASICS OF TEE
How many cross sections constitute a comprehensive TEE examination?
There are 20 cross sections in a comprehensive TEE examination.
BASICS OF TEE
In the OR, why are providers not expected to perform a comprehensive TEE exam for each case?
Time contraint
BASICS OF TEE
In the OR, how many cross-sections are providers required to produce at a minimum from a TEE exam?
A minimum of 8 different cross sections of the total 20 cross sections;
4 of which should both be in 2-D and color doppler to assess valvular funtcion
COMPREHENSIVE EXAMINATION
Describe a comprehensive TEE examination
THIS IS A DEPICTION OF THE COMPREHENSIVE EXAMINATION.
FOR A FULL BREAKDOWN OF EACH INDIVIDUAL VIEW, PLEASE VISIT THE WEBSITE TO BE REDIRECTED TO THE GUIDELINES FOR PERFORMING A COMPREHENSIVE TEE EXAMINATION
http://www.asecho.org/wordpress/wp-content/uploads/2014/05/2013_Performing-Comprehensive-TEE.pdf
BASICS OF TEE
When used in open heart surgery, when is TEE usually placed
Once General Anesthesia is induced
OGT placed to facilitate emptying of stomach
BASICS OF TEE
Why is a bite block placed in patient’s mouth prior to insertion of TEE probe?
To prevent damage to the piezoelectrodes in the probe
BASICS OF TEE
How is the tip of the TEE probe inserted into the esophagus?
Tip of the TEE probe is covered with surgical lubricant and passed “blindly” into the esophagus
Jaw lift or laryngoscope blade if unable to pass probe “blindly”
Elevate head of resistance
BASICS OF TEE
When the TEE probe is inserted, how is it manipulated so the aortic valve can be visualized?
Inserted to TEE probe to 30 cm at the upper incisors
Rotate the transducer until the three cups of the valve are visualized
BASICS OF TEE
In what percentage of cases is the provider unable to insert TEE probe?
2%
COMPLICATIONS OF THE TEE
T/F: TEE is traumatic and unsafe
False
TEE is very safe and atraumatic if placed correctly
COMPLICATIONS OF THE TEE
How can complications such as Esophageal tears or perforations and burns associated with TEE insertion be avoided?
The probe should be introduced with gentleness and care and if ANY resistance is encountered, the probe should be withdrawn and re-lubed and then another attempt can be made to place it
COMPLICATIONS OF THE TEE
Why should the TEE machine always be placed on stanby mode when not in use? How is this done?
To avoid burn in the esophagus
This is done by pressing “freeze” on the monitor
CONTRAINDICATIONS FOR TEE
Absolute contraindications to TEE placement are:
Presence of an esophageal obstruction
Esophageal perforation
Prior esophagectomy
Esophageal tumor
Recent suture lines as in gastric bypass
CONTRAINDICATIONS FOR TEE
Relative contraindications for TEE include:
Hiatal Hernia
Esophageal varices
Esophagitis
Unexplained swallowing difficulties
Mediastinal radiation
Esophageal diverticulum
Unexplained swallowing difficulties
