Study for Examination of Special Competence in Critical Care Echocardiography, (CCEeXAM®)
When does flattening of the interventricular septum (IVS) occur?
- Pressure overload: Septum flattens most at end systole
→ RV pressure peaks during systole
- Volume overload: Septum flattens most at end diastole
→ RV is volume loaded during diastole
- IVS flattening is a clue to right heart strain pattern
- Paradoxical septal motion may occur in volume overload
What is the eccentricity index and how does it change?
- Eccentricity index = LV anterior-posterior diameter ÷ septal-lateral diameter
- Normally equals 1 (circular LV shape) at systole and diastole
- Pressure overload: Index >1 in both systole and diastole
- Volume overload: Index >1 only at end diastole
- Helps assess abnormal IVS motion
How do you differentiate the right ventricle (RV) from the left ventricle (LV)?
- RV has:
- Moderator band
- Three papillary muscles
- More apically displaced AV valve
- Thinner wall (usually)
- Moderator band connects anterior papillary muscle to IVS
What right ventricular (RV) dimension indicates enlargement?
- Basal diameter >41 mm at end diastole = dilated RV
- Other thresholds:
- Mid RV diameter >35 mm
- RV length >83 mm
- Use largest measurements from multiple views
How is systolic pulmonary artery pressure (SPAP) calculated?
- Use TR peak velocity and RAP:
SPAP = 4 × (TR velocity)² + RAP
- Example: 2 m/s TR velocity, RAP = 12 mm Hg
→ 4 × 4 + 12 = 28 mm Hg
What is the key step in calculating SPAP using TR jet?
- TR velocity must be squared using Bernoulli equation:
P = 4 × V²
- Best TR signal requires alignment and multiple views
- Avoid using TR velocity if pulmonary stenosis or severe TR is present
How can pulmonary regurgitation (PR) estimate pulmonary pressures?
- Use parasternal short-axis view
- PR peak diastolic velocity estimates mean PAP (MPAP):
MPAP = 4 × (PR velocity)² + RAP
- PR end-diastolic velocity estimates diastolic PAP
- Example:
- PR peak = 3 m/s → 4 × 9 + 8 = 44 mm Hg (MPAP)
- PR end = 1 m/s → 4 × 1 + 8 = 12 mm Hg (DPAP)
What affects accuracy of dP/dt in RV systolic function?
- Requires TR during isovolumic contraction
- Calculate slope between 0.5 and 2 m/s
- Normal: dP/dt >400 mm Hg/s or dt <37.5 ms
- Large, eccentric, or trivial TR may make it unreliable
What increases the risk of RVOT obstruction?
- Hypovolemia, RV hypertrophy, inotropes increase risk
- Hypervolemia does not
- RVOT obstruction = >25 mm Hg gradient
- Treated by reducing HR/inotropes, increasing preload
What is RV fractional area change (FAC)?
- Formula:
RVFAC = (RVEDA − RVESA) / RVEDA × 100
- Normal >35%
- Estimates global RV systolic function
- Correlates with MRI-measured RVEF
What’s the best approach for measuring RV dimensions?
- Use apical four-chamber view focused on RV
- Ensure largest RV basal diameter with LV apex centered
- Avoid relying on visual estimates
- Avoid LV-focused images for RV measurements
What is McConnell’s sign?
- Basal/mid RV free wall hypokinesis
- Apical RV sparing or hyperkinesis
- Seen in acute PE
- Specific for acute RV strain
- Not exclusive to PE but highly suggestive
What is the definitive echo sign of pulmonary embolism?
- Direct visualization of thrombus in the pulmonary artery
- Supporting findings:
- Enlarged RV
- McConnell’s sign
- TR
- Abnormal septal motion
What is the moderator band?
- Muscular ridge in RV containing right bundle branch
- Extends from lower IVS to anterior papillary muscle
- Not found in the RA (confused with Chiari network)
What indicates severe tricuspid regurgitation (TR)?
- Systolic flow reversal in hepatic veins
- Dense, triangular Doppler signal
- Vena contracta ≥7 mm
- Large regurgitant jet filling >50% of RA
What is typical RV blood supply?
- RCA → main RV supply
- Posterior descending artery → posterior 1/3 of septum
- LAD may supply part of RV apex
- RV infarct varies by coronary dominance
What causes RV wall thickening?
- Pulmonary hypertension
- COPD
- Pulmonary stenosis
- Not: Arrhythmogenic RV dysplasia (causes wall thinning)
What can cause refractory hypoxemia in pulmonary hypertension?
- Right-to-left shunt via patent foramen ovale (PFO)
- Use TEE and agitated saline for detection
- PFO present in up to 25% of adults
How does RV diastolic function differ from LV?
- Lower velocities in RV inflow due to larger tricuspid annulus
- More respiratory variation in RV than LV
- Tissue Doppler:
- e′ > a′ in normal
- e′/a′ <1 = impaired relaxation
- More severe diastolic dysfunction → high E/A, persistently low e′/a′
What is the hepatic vein flow pattern in end-stage RV failure?
- Reversed systolic flow (S wave)
- Blunted diastolic flow (D wave)
- Reflects severe diastolic dysfunction
What shows improvement after milrinone in RV failure?
- Decreased TR severity
- Increased S′ and TAPSE
- Decreased RV end-systolic area
- Reflects improved contractility and decreased afterload
What echo sign suggests tamponade?
- Right atrial collapse during systole
- Right ventricular collapse during diastole
- Reciprocal respiratory inflow variation may also be present
What echo view is used to calculate RV cardiac output?
- Parasternal short-axis view
- Use it to:
- Measure RVOT diameter
- Calculate RVOT area
- Measure VTI with pulse Doppler
- Multiply: CO = HR × Area × VTI
How is right atrial pressure (RAP) estimated by IVC?
- IVC >2.1 cm + <50% collapsibility → RAP = 15 mm Hg
- IVC <2.1 cm + >50% collapsibility → RAP = 3 mm Hg
- Intermediate = 8 mm Hg
- Use both transverse and longitudinal IVC views when possible