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Echo Flashcards

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USMLE® Step 1 flashcards
1
Q

What are typical echo findings of mitral stenosis on 2D Echo?

A
  • Diastolic “doming” of the anterior mitral valve leaflet - “hockey stick” appearance (best seen on parasternal long axis view)
  • Commisural fusion - “fish mouth appearance” (best seen on parasternal short axis view)
  • Left atrial dilatation
  • Left atrial spontaneous echo contrast - “smoke”
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2
Q

Define Aliasing

A
  • imaging error which occurs due to under-sampling
  • Occurs in PW doppler where there is an upper limit of doppler shift which can be displayed - Nyquist limit
  • US system is trying to image an event that is occuring faster than the rate we are sampling it
  • As a result the system is uncertain about the direction of the signal and displays this as heading in the opposite direction
  • Occurs in both color and spectral Doppler, where the velocity exceeds the Nyquist limit
  • “Wagon-wheel” effect (wheels turning in the opposite direction as it turns at a faster rate)
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3
Q

Define Nyquist Limit

A
  • Half of the sampling rate of a discrete signal processing system
  • Sometimes known as “folding frequency”
    *
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4
Q

What is the PISA method for determining MVA?

A

MVA cm2 =

  • 6.28 x r2 x Aliasing velocity
  • Mitral ValveE Wave Velocity (Vmax)
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5
Q

What is the equation for MVA by P 1/2 time?

A

MVA cm2 = 220 / PHT

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6
Q

What are the Level 1 ASE recommendations for Mitral stenosis?

A
  • MVA planimetry
    • using the parasternal short axis of the mitral level in mid-diastole
  • MVA using PHT method
  • Mean pressure gradient
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7
Q

What are teh Level 2 ASE recommendations for evaluation of mitral stenosis?

A
  • MVA by continuity equation
  • MVA by PISA method
  • MVA and SPAP with stress echocardiography
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8
Q

What situations can PHT method overestimate MVA?

A
  • Decreased PHT
    • Significant AR
    • ASD
    • Decreased LV compliance
    • Sudden change in LA compliance (fever, anemia, tachycardia, acute MR, exercise)
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9
Q

What situations can PHT method underestimate MVA?

A
  • Increased PHT
    • Decreased rate of LV relaxation
    • Immediately following PMBV
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10
Q

What situations will result in a discrepancy between the MVA by PHT and planimetry?

A
  • MR
  • High-cardiac output
  • Tachycardia

***increased transmitral flow can raise the gradient out of proportion to the calculated and planimetered MVA

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11
Q

What are the branches of the aortic arch (in order)?

A
  • brachiocephalic
    • Right subclavian
    • Right common carotid
  • Left common carotid
  • Left Subclavian
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12
Q

What are the key elements of standard echocardiographic systems?

A
  • transducer with piezoelectric crystals
    • transmits ultrasound waves and receives ultrasound echoes produced when the ultrasound waves reflect back off of human tissue
  • computerized system tha programs the generation of ultrasound waves, processes the received signals, and stores the data
  • display for visualization and interpretation of data, either in real-time or offline.
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13
Q

What is the equation for describing the behavior of ultrasound waves?

A

λ = c/f

  • λ = wavelength or peak-to-peak
  • c = velocity of the us wave
  • f = frequency of the us wave
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14
Q

What is the velocity of US waves in human tissues?

A

1540 m/sec (1.54 mm/μsec)

  • localization of objects is based fundamentally on the speed of propagation of sound waves
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15
Q

What determines the fundamental limit of resolution in ultrasound?

A

Wavelength

  • approximately 2x wavelength
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16
Q

Explain advantages / disadvantages of higher frequency?

A
  • better image resolution
  • decreased penetrance (only penetrate a short distance in the body)
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17
Q

Define acoustic impedance

A
  • physical property of tissue
  • describes how much resistance an ultrasound beam encounters as it passes through a tissue
  • dependent on the density of the tissue
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18
Q

Sound waves cannot travel through this?

A

vacuum

  • pressure waves can be transmitted only trhough physical media consisting of molecules that interact with each other
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19
Q

Ultrasound is a pressure wave with a frequency that is above the limit of human hearing, which is?

A

20, 000 Hz or 20 kHz

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20
Q

The frequency of a sound wave is measured in Hz and is defined as?

A

number of times particles vibrate each second in the direction of wave propagation

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21
Q

Ultrasound imaging is usually performed using frequencies in this range?

A

1-30 MHz

  • lower frequencies in this range are used to image large organs or deeper structures that require significant penetration depth
  • higher frequencies in this range are used for smaller and more superficial structures that require less depth but better spatial resolution
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22
Q

Define Pressure Half-Time

A

the time interval in milliseconds between the maximum mitral gradient in early diastole and the time point where the gradient is half the maximum initial value.

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23
Q

Define Bruce Protocol

A
  • Developed in 1963 by Robert A. Bruce
  • standardized multistage treadmill test for assessing cardiovascular health
  • patient walks on an uphill treadmill in a graded exercise test with electrodes on the chest to monitor the EKG.
  • Every 3 minutes, the speed and incline of the treadmill are increased (3 Mets increase)
  • 7 stages, only very fit athletes can complete all 7 stages
  • Modified Bruce Protocol –> treadmill initially horizontal, instead of sloped
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24
Q

What are two of the most serios contraindications to ETT that can sometimes be overlooked?

A
  • Aortic dissection
  • Pulmonary Embolus
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25
Q

What are the absolute contraindications to ETT?

A
  • CHF, uncontrolled
  • High-risk UA
  • Arrhythmia, uncontrolled
  • Aortic Dissection
  • Acute MI
  • Myocarditis / Pericarditis
  • Pulmonary Embolus
  • Severe symptomatic AS
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26
Q

What are the relative contraindications to ETT?

A
  • Stenotic heart disease (moderate)
  • Tachy/bradyarrythmia
  • Electrolyte abnormalities
  • AV block (high-degree)
  • LMCA disease
  • Hypertension (BP > 200/110 mmHg)
  • HOCM
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27
Q

What are indications to stop ETT?

A
  • Patien’ts desire to stop
  • CNS symptoms
  • Moderate angina
  • Arrhythmias (serious)
  • ST-elevation > 1.0mm
  • Hypotension (SBP drop > 10 mmHg below baseline)
  • Hypertension (SBP > 220 mmHg)
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28
Q

What is the hallmark of an abnormal ETT?

How is this abnormal response defined?

A
  • ST-segment depression
  • ≥ 1.0mm horizaontal or downsloping ST-segment depression measured 0.08 seconds after the J point
29
Q

What are additional features of an ETT that increase the likelihood of a true-positive test result?

A
  • Occurrence at a low exercise workload
  • Involvement of several EKG leads
  • Greater magnitude of depression
  • Longer persistence in the recovery period.
30
Q

What is the significance of ST-depression that occurs only in the recovery period?

A

same diagnostic accuracy as ST-segment depression during exercise

31
Q

What are the most frequently identified lead abnormalities on ETT?

A
  • Positive responses in V4-V6 ( > 90%) regardless of site of anatomical CAD
  • ST-depression confined to inferior leads –> usually represents false positive findings
32
Q

When does ST-elevation usually show up on ETT?

What does this mean?

A
  • Can be arrythmogenic if exercise continues.
  • Can localize site of myocardial ischemia (unlike ST-depression) and usually indicates high-grade stenosis
33
Q

What EKG findings preclude interpretation of exercise EKG?

A
  • Paced ventricular rhythm
  • Pre-excitation (WPW)
  • LBBB
  • Reduce specicity –> ST-T abnormalities, Digoxin use, LVH
34
Q

Can ETT/EKG interpretation be performed in the setting of RBBB?

A
  • Yes
  • Right precordial leads (V1-V3) must be ignored and interpretation is confined to left precordial leads (V4-V6)
35
Q

What are the three clinical CAD risk categories defined by the ACC/AHA?

A
  • Low ( < 1% mortality rate)
  • Intermediate ( 1-3% mortality rate)
  • High ( > 3% mortality rate)
36
Q

What is the most important/strognest prognostic ETT variable?

A
  • Exercise capacity / duration
    • patient’s at high risk for left main/three-vessel CAD
    • high clinical event rate
37
Q

What are clinical variables in ETT that identify higher-risk patients?

A
  • Poor exercise capacity
  • Hypotension, exercise induced
  • Chronotropic incompetence
    • during exercise or or post-exercise
  • Ventricular ectopy
  • ST-depression (weaker than other variables)
38
Q

Define Duke Treadmill Score (DTS)

A
  • weighted index combining:
    • treadmill exercise time using standard Bruce protocol
    • maximum net ST segment deviation (depression or elevation)
    • exercise-induced angina.
  • Developed to provide accurate diagnostic and prognostic information for the evaluation of patients with suspected coronary heart disease.
  • Typical observed range of DTS is from -25 (highest risk) to +15 (lowest risk).
39
Q

What is the equation for the DTS?

A
41
Q

What are the recommendations for pre-operative stress testing?

A
  • Elevated risk and poor functional capacity –> pharmacologic stress testing, if it will change management (Class IIa)
  • Elevated risk and unknown functional capacity –> exercise testing to assess functional capacity if it will change management (Class IIb)
  • Elevated risk and poor ( < 4 METS) or unknown functional capacity –> exercise testing with cardiac imaging to assess for myocardial ischemia if it will change management (Class IIb)
  • Testing not recommended for low-risk surgery (Class III)
  • Reasonable to forgo exercise testing and proceed to surgery in patients with elevated risk and excellent functional capacity, defined as > 10 METS (Class IIa)
  • Reasonable to forgo exercise testing and proceed to surgery in patients with elevated risk and moderate to good functional capacity, defined as 4-10 METS (Class IIb)
42
Q

In what groups of patients should stress imaging be the initial testing modality?

A
  • inability to exercise with requirement for pharmacologic stress
  • significant abnormalities on resting EKG that preclude interpretation of the stress EKG
  • high pretest probability of CAD
43
Q

What are the Class I indications for stress testing?

A
  • Standard ETT in patients at intermediate pretest probability of CAD who can exercise and have interpretable EKG
  • Exercise imaging in patients at intermediate or high pretest probability of CAD who can exercise and have an uniterpretable EKG
  • Pharmacologic imaging in patients with intermediate or high pretest probability of CAD who are unable to exercise.
44
Q

How to obtain the parasternal long axis view?

A
  • Position the TTE transducer:
    • 3rd-4th intercostal space
    • at left parasternal border
    • index marker pointing toward the right shoulder (11 o’clock)
  • Adjust sector depth to:
    • 10-16 cm to see the descending aorta in SAX
    • increase to 20cm to assess for a left pleural effusion
45
Q

What are the assessment goals in parasternal long axis?

A
  • LV size and function
  • RV size
  • Mitral valve
  • Aortic valve
  • Left pleural effusion
  • Pericardial effusion
  • Aortic dissection
46
Q

What structures can be identified in parasternal long axis view?

A
  • Aortic Valve
  • Descending aorta (Ao)
  • Inter-ventricular septum (IVS)
  • Left atrium (LA)
  • LV
  • Mitral valve
  • RVOT
47
Q

What structures can be identified in parasternal short axis view?

A
  • Anterolateral papillary muscle (AL)
  • Inter-ventricular septum (IVS)
  • LV
  • Posteromedial Papillary Muscle (PM)
  • RV
48
Q

What should parasternal short axis be used to assess?

A
  • LV size and function
  • RV size and function
  • Pericardial effusion
49
Q

How to obtain parasternal short axis view?

A
  • Position the TTE transducer
    • 3rd-4th intercostal space
    • left parasternal border
    • index marker poiting towards the left shoulder (2 oclock)
    • view can easily be obtained by rotating the probe 90 degrees clockwise from the parasternal LAX view and tilting the probe downards
  • Adjust the sector deptht to:
    • 10-16 cm to see the entire LV
50
Q

What structures should be identified in the apical four chamber view?

A
  • Descending Aorta (Ao)
  • Inter-atrial septum (IAS)
  • LA
  • Left lower pulmonary vein (LLPV)
  • LV
  • MV
  • RA
  • Right upper pulmonary vein (RUPV)
  • RV
  • TV
51
Q

How to obtain apical four chamber view?

A
  • Position the TTE transducer
    • 4th or 5th intercostal space
    • midclavicular line or at the point of apical pulsation
    • index marker pointing towards the left (3 oclock)
  • Adjust the sector depth to:
    • 14-18cm to image the atria
    • 6-10 cm to assess the LV apex
52
Q

What should the apical four chamber view be used to assess?

A
  • LV, RV size and function
  • RA and LA size and function
  • MV and TV’s
  • Pericardial effusion
53
Q

What should the subcostal four chamber view be used to assess?

A
  • LV, RV size and function
  • MV and TV’s
  • RA, LA size and function
  • Pericardial effusion
  • Cardiac motion during code blue
54
Q

What structures should be identified on subcostal four chamber view?

A
  • Inter-atrial septum (IAS)
  • Inter-ventricular septum (IVS)
  • LA
  • RA
  • MV
  • TV
  • RV
  • LV
  • Liver
55
Q

How to obtain subcostal four chamber view?

A
  • Position the TTE transducer:
    • subxiphoid region of the abdomen
    • flat and push down with a slight tile to the patients right
    • index marker pointing towards the left (3 oclock)
  • Adjust the sector depth to:
    • 16-24cm to image the entire LA and LV
56
Q

How to obtain the subcostal IVC view?

A
  • Position the TTE transducer:
    • in the subxiphoid region of the abdomen
    • tilt to the patient’s left
    • index marker pointing towards the head (12 oclock)
    • view can easily be obtained by rotating the probe 90 degrees counterclockwise from the subcostal 4C view
  • Adjust the sector depth to:
    • 16-24cm to image the entire IVC
57
Q

What should the subcostal IVC view be used to assess?

A
  • IVC size (measure in mm or cm)
  • change in IVC size with respiration (use m-mode)
58
Q

What structures should be identified on the subcostal IVC view?

A
  • IVC
  • Liver
  • RA
59
Q

What are the most common indications for TEE?

A
  • left atrial thrombus evaluation
  • endocarditis
  • prosthetic valve function
  • perioperative cardiac surgery complications
  • providing guidance in transcatheter procedures
60
Q

What are the major complications associated with TEE?

A
  • Cervical spine immobility
  • Recent Upper GI surgeries
  • Esophageal strictures
  • Prior perforated upper GI structures
  • Upper GI bleed (active)
61
Q

TEE terms:

  • Advance
  • Withdraw
  • Turn
  • Flexion
  • Extension
  • Rotation
A
  • Advance: vertical forward motion of probe
  • Withdraw: vertical backward motion of probe
  • Turn: rotation of entire probe
  • Flexion/Extension: motion of tipe of the probe in a plane parallel to the long-axis of the probe, controlled by a large dial at the base of the probe
  • Rotation: electronic movement of the image plane in a circular fasion, controlled by a button on the probe and displayed as an angle on the image
62
Q

Describe the difference (incidence, location, degree of injury) in CHB in anterior vs. inferior MI?

A

Inferior

  • 4% of patients, may be transient
  • associated with higher location of AV block (typically the AV node)
  • lesser degree of myocardial injury

Anterior

  • 1% of patients, serious complication of anterior MI, poorer short term outcomes (including survival)
  • associated with lower location of block is usually below the AV node –> higher long-term block
  • greater degree of myocardial injury
63
Q

What is the starting view for TEE?

How to obtain this view?

A
  • Mid-esophageal 4-chamber view
  • Mid-esophageal positioning, 0 degree rotation, maximum depth to show the entire LV, probe extended to include as much of the apex as possible
64
Q

What are the second and third images obtained on a TEE?

A

After obtaining ME apical 4-chamber view:

  • 2nd –> ME, apical, 2 chamber view –> rotating to 60 degrees
  • 3rd –> ME, apical, Long axis (LAX) view –> rotating to 120 degrees
65
Q

TEE views utilized to assess regional LV function / EF?

A
  • lateral wall and inferior septum –> ME, A4C
  • anterior and inferior walls –> ME, A2C
  • anterior septum and inferior lateral wall –> ME, ALAX
66
Q

Quantitative EF measurements in TEE can be made utilizing what methods?

A
  • 3D full volume acquisition with automated border detection
  • Biplane approach with tracing of endocardial borders at end-diastole and end-systole in A4C ad A2C views
67
Q

What TEE view is this?

How to obtain the view?

What is this view used for?

A
  • ME, Bicaval view
  • Obtain ME, A4C –> rotate to 90-100 degrees and turn probe right
  • ASD (secundum, sinus venosus), Atrial pathology, Lines/wires, Venous cannula (SVC, IVC)
68
Q

What is the best TEE view for evluating the LAA?

A
  • ME, A2C
  • imaged in two orthogonal planes (0 and 90 degrees)
70
Q

What are the branches of the celiac trunk?

A
  • Splenic artery
  • Left gastric
  • Common Hepatic

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