The Sonographer Attachment Programme At USA Report : Mayo Clinic Rochester = 2D Strain=

5.8 Mayo Clinic Stress Echo Lab Gonda 6:

Protocol For Tranthoracic Echocardiogram (TTE) Strain Imaging

      Principles

·    This protocol is designed to provide guidance when Echo Lab staff are performing a strain echocardiogram.

      Indications

Myocardial strain is a dimensionless index of change in myocardial length in response to an applied force.Rate (SR) is the rate of change of length and is usually obtained as the time derivative of the signal.SRI may be superior to Doppler tissue imaging in quantitative assessment of regional myocardial function and may find clinical application in the interrogation of coronary artery disease. The high temporal resolution allows SRI to depict regional systolic and diastolic asynchrony.Potential clinical applications include investigation of ischemia (at rest and with stress), myocardial viability, and altered global and regional systolic and diastolic function in cardiomyopathies.

      Medications

·         Contrast agents

      Patient Educations

·         Information about echocardiography is printed on each patient’s itinerary of Clinic tests.  Prior to beginning the study, the imaging sonographer or physician explains the procedure and process of reviewing results; any additional teaching (i.e., Valsalva maneuver, strain imaging, etc.) is provided as needed. Explanation of the test result is deferred to the referring physician.

Standard Protocol (GE VIVID 7)

Image Acquisition

·         Set the data flow on the echo machine to “internal hard drive”.

·         Do not select the strain setting: a three beat capture is sufficient.

·         Do not set the preview to “on”.

·         Optimize the ECG. If at all possible, have the highest point of the ECG be at the onset of the QRS. 

Imaging Parasternal Window

·         Acquire 2D images of the short axis at the base, mid and apex with dual focus off, with as narrow a sector as possible (frame rate >40). All views should be acquired with the same frame rate. The frame rate can be manipulated with the frame rate knob. Be careful not to turn it up more than one or two clicks as this will degrade the lateral resolution.

Imaging Apical Window

Acquire 2D images of 4 chamber, LAX, and 2 chamber, with dual focus off, with as narrow a sector as possible (frame rate >40). Acquire images of the LV only and decrease depth and width accordingly. Do not cut off the walls at the apex - make sure walls at apex can be seen throughout the cardiac cycle. All views should be acquired with the same frame rate.

Acquire TDI images of the full 4 chamber view, apical LAX, and 2 chamber views. Acquire images of the LV only, so decrease depth and width accordingly. It is not necessary to see the apex well as we only make Doppler measurements of the base and mid walls

Acquire PW Doppler of the LVOT and the mitral inflow (with sample placed closer to the annulus to see valve clicks, and filters set low).

Transfer To Echo Pac

     Click the “new exam” button to finish study and complete copy to hard drive, Click the “export” button, select “echo pac” or “remote import/export archive” for destinationand click “copy” to start the transfer. When “OK” appears, click it and then click “done” to finish the transfer,  If continuing on with the standard echo, make sure you reset the data flow to “internal hard drive/ DICOM server”, then select “patient/study” (not “create”). You will be asked if you wish to continue with the exam/study. Click “no”. You should not see the thumbnails of the strain examination.

Image Storage

·         Raw data will be sent directly to the Echo Pac.

·         Before analysis, save images to a 5.25” M.O. disk.

Analysis 

• Select study and open on the Echo Pac.
• Double click LVOT Doppler thumbnail to open, then click and drag to expand the signal. Click on measure, click on event timing, mark AVO at beginning of LVOT flow, and mark AVC at end of flow. Perform one time only; there is no need to save.
• For all studies, measure and save the Doppler based strain of the inferoseptal basal segment only.

• Start with apical LAX 2D view. Click and open.
• Click on “measure”.
• Click on AFI (automated functional imaging).
• Click  APLAX
• Place hand cursor on endocardial/chamber interface at basal inferolateral wall, anteroseptal wall and apex.
• System will extrapolate wall placement and thickness. If optimal, wait for the system to proceed.
• Adjust endocardial border and thickness of ROI if needed.

• If all walls are seen well, green V’s will show up below wall segments. If not seen well, red X’s will instead be shown.
• If successful, click on “approve”.  If not successful, click on “recalculate”. Drag points on wall to optimize. If still unsuccessful, click “new ROI” and start over.
• Doppler based and speckle strain may need to be measured after aortic valve closure. The fixed green bar indicates automatically determined AVC timing. With the movable green bar click two increments to the right of the fixed green bar. The machine asks “auto” or “manual”. Click “manual” as long as aortic valve closure timing is visible in the 2D image.

• Click exit
• Click on 4chamber view to open
• Click on 4 chamber
• Follow same directions used for ALAX
• Click on 2 chamber view to open
• Click on 2 chamber
• Follow same directions used for ALAX
• Approve
• First view up is 3 views + BE (bulls eye view)
• Click on snapshot
• Click on BE (bulls eye view only)
• If there are varying heart rates between the three captures, the bulls eye cannot be displayed. Obtain the speckle information by the manual method.

Analysis Manual

• Double click on the apical LAX 2D view to open.
• Click on Q-analysis, then 2D strain.
• A drop down menu will appear, then click on APLAX.

• Place hand cursor on endocardial/ chamber interface at basal inferolateral wall. Do the same for anteroseptal wall and apex. No headers will appear. Double clicking on the apex causes an automatic trace to appear. Follow instructions per AFI.
• To record the averaged strain for a particular view, show the waveforms for that wall. Place the cursor on the peak downward white dotted line and read the strain % average of this view at top of screen. Before leaving this view, place the cursor on the color coded tracings for the individual walls and read the strain percent at the top of the page. Note this value for each of the color coded tracings and record in the EIMS strain measurements. 
• Click “exit”.  When asked if you wish to store the loop, click “yes”.
• Repeat for the four and two chamber views.
• Average the strain % averages of the three views to calculate the overall global average.

Reporting

• The overall global average will be reported for all studies. Using the bulls eye view for a guide, also enter the strain for each individual wall in the EIMS measurement section. Enter the numbers exactly as seen on the bulls eye (negative or positive).
• As the speckle strain numbers will be in the usual strain measurement slots in EIMS, the best place for the Doppler based strain of the basal inferoseptum is in the comment balloon. Be specific about the wall as the comment is placed at the bottom of the strain measurements.
• Report the averaged strain on all studies. Also report the area/areas of the most abnormal strain. 
• Dyssynchony is not being evaluated with speckle at this point.
• Report Amyloid or HCM strain as follows:

The averaged LV systolic longitudinal strain is abnormal/normal at -?% (normal =more negative than -18%).  The most abnormal walls are (example) basal anterior segments.