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Notes on Right Ventricular Function


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?

  •  HypovolemiaRV hypertrophyinotropes 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