Echo, Fetal Echo and Advanced Imaging Flashcards
What makes echo axial resolution better
Higher transducer frequency
What makes echo lateral resolution better
- Narrower ultrasound beam width
- Larger size probe, higher frequency and focusing
What makes echo temporal resolution (frame rate) better
- Decreasing depth (less time for farthest wave to return)
- Narrowing sector
- Lower line density
- Single focal point
- Parallel beam forming
Shortening fraction equation
%FS = (EDD-ESD) / EDD x 100
Ejection fraction equation
%EF = (EDV-ESV) / EDV x 100
Normal markers of diastolic function (E/A, E’, E/E’)
- E/A: 2
- E’ > 10
- E/E’ < 10
Abnormal relaxation markers of diastolic function (E/A, E’, E/E’)
- E/A: < 1
- E’ < 10
- E/E’ < 10
Pseudonormalization markers of diastolic function (E/A, E’, E/E’)
- E/A: 0.8-2
- E’ < 10
- E/E’ > 10
Restrictive markers of diastolic function (E/A, E’, E/E’)
- E/A: >2
- E’ < 10
- E/E’ > 10 (usually really high)
TEE absolute contraindications
- Unrepaired TEF
- Esophageal obstruction
- Poor airway control
- Uncooperative unsedated patient
TEE relative contraindications
- Previous esophageal surgery with possible residual obstruction
- Esophageal varices
- Vascular ring or anomaly that could produce airway obstruction
- Severe coagulopathy
- Cervical spine injury or instability
Stress echo indications
- Coronary artery disease: diagnosis/risk stratification
- Exertional dyspnea
- PH
- Mitral stenosis/insufficiency
- Aortic stenosis (LV dysfunction and low grade stenosis, use dobutamine)
- HOCM
What does LGE on MRI show
- Myocardial infarction
- Fibrosis
- Myocarditis
- Endocardial fibroelastosis
Reasons to use CT instead of MRI
- Contraindication to MRI (pacemaker, ICD)
- Metallic implants cause too much artifact on MRI to see structures of interest
- Sedation needed for MRI but not CT
- Critically ill or unstable patient (dissection, PE)
- Airway and lung tissue evaluation is primary
- Coronary artery stenosis
Normal lung perfusion scan differential R to L
- Right 55%
- Left 45%
Indications for lung perfusion scan
- PA stenosis
- Pulmonary vein stenosis
Normal septal to free wall thickness in adolescent
- 1.1 (range 0.8 to 1.4)
- Increases in adult to average of 1.2
Indications for fetal echo
- Familial (CHD in sib or parent)
- Maternal (DM, PKU, autoantibodies, drug exposure, rubella, assisted reproduction)
- Fetal (suspicion CHD, fetal arrhythmia, extracardiac malformations, increased nuchal thickness, genetic abnormality, single umbilical artery, twins, hydrops)
Risks with absent ductus venosus
- CHD, volume overload, heart failure
Problems with restrictive PFO
- RV dilation, TR, small left sided structuresP
Problems with restrictive PDA
RV dilation or dysfunction, TR, neonatal PH
- Fetal echo with flow velocity > 1.4 m/s
Most common type of tumor in kids, especially infants
Rhabdomyomas
Well circumscribed, non-capsulated, intramural or intracavitary nodules that can occur anywhre in the heart
Rhabdomyomas
- Appear bright on echo
- Often multiple
Presenting symptoms for cardiac myxoma
- Obstruction (80%)
- Embolism (70%)
- Systemic illness (60%)
Pedunculated friable masses commonly in the left atrium and can be attached to foramen ovale
Causes of reversal of flow in descending aorta
- PDA
- Severe AI
- Intracranial AV malformation (Vein of Galen malformation
How soon do microbubbles appear in left heart with agitated saline injection
If there is an intrapulmonary shunt it is usually in 3-5 cardiac cycles versus 1-2 cardiac cycles for intracardiac shunt
Best echo view for secundum ASD
Subcostal four chamber view
Echo findings for restrictive LV physiology
- Increased mitral inflow doppler E:A ratio > 2
- Shortened mitral E wave deceleration time < 160 ms
- Decreased lateral mitral Ea velocity
- Increased E/E’ ratio > 15
Definition of nyquist limit
Maximal frequency shift detectably by PW doppler
Equal to 1/2 of the PRF
Echo definitions of cardiac tamponade
Respiratory changes in doppler flow across tricuspid valve of > 30% and mitral valve of > 25%
Can also see diastolic right atrial and right ventricular collpase
Most common type of VSD associated with coarctation
Perimembranous
Posterior malalignment
Most reliable way to distinguish a mitral from tricuspid valve
Level of attachment at the crux of the heart
Normal fetal-thoracic area ratio
25-35%
About 1/3
Common causes of hypertrophy on fetal echo
Recipient twin in twin-twin transfusion
Fetus of diabetic mother
Fetal hypertrophic cardiomyopathy
Fetal Noonan syndrome
What are uses for spin echo MRI technique
Black blood imaging - myocardium/tissue are different gray/white colors
- Imaging myocardial and blood vessel walls
- Cardiac tumors/masses
- Pericardium
T1/T2 weighted sequences in spin echo imaging help with tissue characterization
