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. 

Exercise Echocardiogram

What is an Exercise Echocardiogram?

An exercise echocardiogram, also known as a stress echocardiogram, is a test that combines an ultrasound study of the heart with an exercise test. The test allows doctors to learn how the heart functions when it is made to work harder.

The exercise echocardiogram is especially useful in diagnosing coronary artery disease, the presence of blockages in the coronary arteries (the vessels that supply oxygen-rich blood to the heart).

Is the Exercise Echocardiogram Safe?

The exercise test is generally safe. A small amount of risk does exist since exercise stresses the heart. Extremely rare complications include abnormal heart rhythms and a heart attack. Experienced personnel are available to handle any emergency.

What Does It Show?

An echocardiogram works very much like sonar. Ultrasound waves are transmitted into the chest and the reflection of these waves off the various parts of the heart is analyzed by sophisticated equipment.

A transducer, which is a small microphone-like device, is held against the chest. The transducer sends and receives the ultrasound waves. By moving the transducer to various positions on the chest, different structures of the heart may be analyzed.

A computer assembles the reflected ultrasound waves to create an image of the heart. These images appear on a television screen. The images may be recorded on videotape or printed on paper for review by the cardiologist.

To provide a baseline of information, an echocardiogram is first done while the patient is at rest. Then, a second echocardiogram is obtained during or immediately after an exercise test using a treadmill.

The images of the heart at rest and during exercise (under stress) are compared. Normally, all areas of the heart muscle pump more vigorously during exercise. If an area of the heart muscle does not pump, as it should during exercise, this often indicates that it is not receiving a sufficient flow of oxygen-rich blood because of a blocked or narrowed coronary artery.

Although an exercise echocardiogram indicates regions of the heart that may be affected by reduced blood flow through the coronary arteries, it does not provide images of the actual coronary arteries. If blocked or narrowed coronary arteries are suspected, your doctor may recommend additional tests.

Preparing For A Test

• Do not eat or drink 3 hours prior to the test. This will prevent the possibility of nausea, which may accompany vigorous exercise after eating. If you are diabetic and take medications for diabetes, get special instructions from your doctor.
• If you are currently taking any heart medications, check with your doctor. You may be asked to stop certain medications a day or two before the test. This can help get more accurate test results.
• Wear loose, comfortable clothing that is suitable for exercise. Men usually don't wear a shirt during the test, and women generally wear a bra and a lightweight blouse or a hospital gown. You should also wear comfortable walking shoes or sneakers.
• Before the test, you will be given an explanation of the test and asked to sign a consent form. Feel free to ask any questions about the procedure.
• Several areas on your chest and shoulders will be cleansed with alcohol and an abrasive lotion, to prepare the skin for the electrodes. Men may need to have areas of their chest shaved, to ensure that the electrodes stay in place.

What Happens During the Test?

The echocardiogram can be performed in the doctor's office or at the hospital. No special preparation is necessary for this test. If you are scheduled for an exercise echocardiogram, however, you will be given special instructions.

You will be asked to remove clothing above the waist, and put on a hospital gown or a sheet to help keep you warm and comfortable. You will then lie on an examination table.

Electrodes (small sticky patches) and wires will be attached to your chest and shoulders to record your electrocardiogram (ECG or EKG). The ECG shows your heart's electrical activity during the test.

Next, you will lie on your back or on your left side. To improve the quality of the pictures, a colorless gel is applied to the area of the chest where the transducer will be placed.

A technician moves the transducer over the chest, to obtain different views of the heart. He or she may ask you to change positions. You may also be asked to breathe slowly or hold your breath, in order to get a better picture. A thorough examination usually takes from 20 minutes to an hour, depending on the number of views and whether the Doppler echo is used.

What Happens During the Test?

Resting Echocardiogram

You will be asked to lie on a hospital bed or examination table. To improve the quality of the pictures, a colorless gel is applied to the area of the chest where the transducer will be placed.

A technician moves the transducer to various places over the left side of your chest. Pictures of your heart at rest are recorded on videotape.

Exercise Test

The exercise portion of the test can be performed in the doctor's office or at the hospital. A trained technician will place several electrodes (small sticky patches) on your chest and shoulders to allow recording of the ECG during exercise. Wires link the electrodes to an ECG machine. A cuff will be applied to your arm to monitor your blood pressure during the test.

You will be shown how to step onto the treadmill and how to use the support railings to maintain your balance. The treadmill starts slowly, and then the speed and incline are increased gradually.

Your blood pressure will be checked every few minutes, and the ECG will be carefully watched for abnormal changes. You will be instructed to report any symptoms, such as chest pain, shortness of breath, leg fatigue, or dizziness.

The test may end when you become too tired to continue or when you experience significant symptoms. Other times, the test may be stopped when you reach your peak heart rate or when your ECG shows abnormal changes.

After the exercise portion of the test is over, you will be helped to a chair or a bed. Your blood pressure and ECG will be monitored while you recover. The technician will remove the electrodes and cleanse the electrode sites. The test typically takes between 45 minutes to one hour, which includes preparation for the test, the exercise portion, and the recovery period.

After-Exercise Echocardiogram

You will be helped back to the examination table. The technician records a second set of images immediately after you finish exercising.

Doctors then compare the two sets of images (before and after exercise) side by side to see how your heart responds to the stress of exercise.

The Results

Typically, the doctor will review the images at a later time and prepare a report detailing his findings.