Transthoracic Echocardiogram

Aka: Transthoracic Echocardiogram, Echocardiogram, Echocardiography, Emergency Echocardiography, Emergency Echocardiogram, Cardiac Ultrasound

1. See Also
   1. Parasternal Long-Axis Echocardiogram View ( PLAX View)
   2. Parasternal Short-Axis Echocardiogram View (PSAX View)
   3. Subcostal Echocardiogram View (Subxiphoid Echocardiogram View)
   4. Apical Four Chamber Echocardiogram View
   5. Suprasternal Echocardiogram View
   6. Echocardiogram in Congestive Heart Failure
   7. Inferior Vena Cava Ultrasound for Volume Status
   8. Emergency Pericardiocentesis
   9. Pericardial Effusion
   10. Stress Echocardiogram
   11. Transesophageal Echocardiogram
   12. Ultrasound
2. Background
   1. Probe Direction Indicator
      1. Issue of confusion on learning Bedside Ultrasound (emergency department and critical care)
      2. Cardiac echo is, by convention, performed with direction indicator on the screen right
         1. Provider should direct the indicator when transverse to point to 3:00 (not 9:00)
         2. Ultrasound machines when on cardiac preset
            1. Automatically move the screen indicator to screen right
         3. All other regional Ultrasound conventions and machine presets (non-cardiac)
            1. Automatically move the indicator to screen left (and pointing to 9:00 position)
      3. Follow simple rule: Probe indicator direction should match the screen indicator direction
         1. Applies when screen directly in front of operator
         2. Check the probe indicators screen position
         3. Observe the screen while tapping or drawing finger across the indicator end
   2. Use Cardiac Phased-Array transducer (1-5 MHz)
      1. Use cardiac preset
         1. Transducer marker corresponds to screen right (contrast with other presets where marker is on screen left)
      2. Optimize the resolution for the intended depth
         1. Deeper structures require lower frequency, often labeled as "penetration mode" (lower resolution)
         2. Superficial structures may be imaged with higher frequency, labeled as "general mode" (and higher resolution)
      3. Faster frame rate (>20 fps is ideal) to catch dynamic images throughout cardiac cycle
         1. Image as shallow as possible (reduce depth)
         2. Narrow the sector (narrow the pie shaped wedge of Ultrasound signals)
         3. Zoom to the area of interest
      4. Avoid using "gain control" to improve image definition
         1. Gain control only adjusts "receiver gain" of the signals that are returning to the scan head (1% of those sent)
         2. Image resolution is based on scan frequency, which is sending signals
         3. Modifying the "receiver gain" only further degrades the resolution
         4. Only after optimizing resolution for depth, should the gain control be used to modify the image brightness
            1. Use the receiver gain only to "darken the snow" or "whiten the landmarks"
   3. Heart axis
      1. Longitudinal refers to long orientation of left ventricle (right Shoulder to left hip)
      2. Longitudinal view will be more horizontal in obese patients and more vertical in thin, tall patients
   4. Most patients will have one adequate view to visualize heart function
      1. Technique for a single view can be modified to visualize most structures
      2. Quality of view may be inversely proportional to body habitus (i.e. Obesity degrades the view)
         1. However, do not pre-adjust machine settings based on habitus alone
         2. Some larger patients have excellent cardiac windows with wide open rib spaces
      3. Subxiphoid Echocardiogram View
         1. Best view in Asthma and COPD
         2. Preferred view during CPR to prevent interruptions
      4. Parasternal long axis
         1. Best view in pregnancy, Obesity and Ascites
      5. Apical Four Chamber Echocardiogram View
         1. May offer a four chamber view, when subcostal view is difficult due to intestinal gas or Obesity
   5. Emergency Echocardiography (or Focused Ultrasound Examination) does not replace a complete Echocardiogram
      1. Emergency Echocardiogram is done to answer specific emergency related questions
      2. Cardiac Arrest evaluation (echo during pulse checks)
         1. Pericardial Effusion
         2. Cardiac activity
      3. Advanced skills
         1. Heart wall motion and cardiac contractility
         2. Valvular abnormalities
      4. Overall Approach (Mnemonic: 5Es)
         1. Ejection Fraction (estimate cardiac contractility or EPSS)
         2. Equality (right heart size in comparison with left)
         3. Effusion (Pericardial Effusion)
         4. Entrance (Inferior Vena Cava Ultrasound)
         5. Exit (aortic root measurement)
   6. Grading cardiac contractility (systolic function, ejection fraction)
      1. Severely reduced (EF<30%)
      2. Mildly reduced (EF 30-55%)
      3. Normal (EF 55-65%)
      4. Hyperdynamic (EF >65%)
   7. Doppler
      1. Pulse and continuous wave doppler signals are only interpretable when flow is parallel to probe
         1. Mitral valve and Tricuspid valve are parallel in Apical 4 Chamber View
         2. Aortic Valve is parallel in Apical 5 Chamber View
      2. Color flow doppler may be used in most views (even when not parallel to flow)
         1. BLUE is flow AWAY from probe and RED is flow TOWARDS probe (Mnemonic: BART)
         2. Color gradient must be adjusted for accurate interpretation
3. Indications: Emergency Echocardiogram
   1. Cardiac Arrest
      1. Cardiac standstill
         1. Evaluate during pulse checks during CPR
         2. A flicker of heart wall motion beyond mitral valve movement may signal cardiac activity
         3. Distinguish from Ventricular Fibrillation appearance (shimmering appearance of ventricular wall)
         4. Distinguish from lung excursion with Positive Pressure Ventilation (stop PPV to visualize heart activity)
         5. Prolonged cardiac standstill may demonstrate congealed blood in ventricle
         6. Associated with little to no chance of ROSC and survival (helps direct cessation of code)
            1. Blaivas (2001) Acad Emerg Med 8:616 [PubMed]
            2. Salen (2001) Acad Emerg Med 8(6): 610-5 [PubMed]
      2. Identify reversible causes of PEA
         1. Cardiac Tamponade (Pericardial Effusion and right ventricular collapse in diastole)
         2. Hypovolemic shock (hyperdynamic heart with with small ventricular chamber)
         3. Pulmonary Embolism (new dilated right ventricular chamber)
         4. Myocardial Infarction (new wall motion abnormality, decreased contractility or EF)
   2. Shock or Hypotension
      1. See RUSH Protocol
   3. Acute Dyspnea
   4. Pulmonary Embolism
      1. Evaluate right heart function
      2. Dilated right ventricle and right atrium
      3. D-Sign (interventricular septum bows into the left ventricle with contractions)
   5. Trauma
      1. See FAST Exam
   6. Myocardial Infarction
      1. Wall motion abnormalities are very challenging to visualize unless severely diminished
      2. Newer Ultrasound machines and technologies may automate analysis
   7. Ultrasound-Guided Pericardiocentesis
   8. Pericardial Effusion
   9. Thoracic Aortic Dissection (Type A)
      1. See Aorta Diameter Measurement on PLAX View
4. Views: General
   1. Parasternal Long-Axis Echocardiogram View ( PLAX View)
      1. 
   2. Parasternal Short-Axis Echocardiogram View (PSAX View)
      1. 
      2. 
   3. Apical Four Chamber Echocardiogram View
      1. 
   4. Subcostal Echocardiogram View (Subxiphoid Echocardiogram View)
      1. 
   5. Suprasternal Echocardiogram View
      1. 
   6. Specific indication views
      1. Echocardiogram in Congestive Heart Failure
      2. Inferior Vena Cava Ultrasound for Volume Status
      3. Emergency Pericardiocentesis
      4. Thoracic Aortic Dissection (Type A)
         1. See Aorta Diameter Measurement on PLAX View
5. Resources
   1. Sub-xiphoid View Video (SonoSite)
      1. http://www.youtube.com/watch?v=1UJ6RodOSTw
   2. Apical 4-Chamber View Video (SonoSite)
      1. http://www.youtube.com/watch?v=_eHZz-OCc_M
   3. Parasternal Long Axis View Video (Sonosite)
      1. http://www.youtube.com/watch?v=4qerzEW_ASU
   4. Parasternal Short Axis View Video (SonoSite)
      1. http://www.youtube.com/watch?v=EaLuCBXXINg
   5. Suprasternal Notch View Video (Sonosite)
      1. http://www.youtube.com/watch?v=Mkc6tUVRgKo
   6. Inferior Vena Cava Ultrasound Video (SonoSite)
      1. http://www.youtube.com/watch?v=ci9W4MvyMHI
   7. Echocardiographer
      1. http://echocardiographer.org/
6. References
   1. Palma (2019) Introduction to Adult Echo Ultrasound Conference, GulfCoast Ultrasound, St. Petersburg
   2. Mateer and Jorgensen (2012) Introduction and Advanced Emergency Medicine Ultrasound Conference, GulfCoast Ultrasound, St. Pete's Beach
   3. Noble (2011) Emergency and Critical Care Ultrasound, Cambridge University Press, New York, p. 61-88
   4. Orman, Dawson and Mallin in Majoewsky (2013) EM:Rap 13(1): 4-6
   5. Reardon (2011) Pocket Atlas Emergency Ultrasound, McGraw Hill, New York, p. 61-106