Right Ventricular Function and Echo

CHAMBER SIZE

• N.B. Given the complex geometry of the RV and the retrosternal nature of the same, chamber size measurements are HIGHLY prone to significant amounts of error
• RV enlargement is suggested if:
  • RV area dimension is larger than LV area in end-diastole in the AP4C (apical four)
  • A linear basal dimension of >4.2cm is also suggestive of significant enlargement
• Like all echo imaging — need to look in multiple windows, to ensure accurate findings
• the RV chamber is normally a crescent curving in front of LV

WALL THICKNESS

• RV hypertrophy from pressure overload (chronic) where the thickness at end-diastole is >5mm (best seen in subcostal views)

RV FUNCTION

• Normal function is restricted mainly to longitudinal (base to apex) shortening and systolic thickening
• Systolic function:
  • TAPSE (Tricuspid Annular Plane Systolic Excursion) normal is >1.7cm (less useful post some cardiac surgery) [measured in AP4C w/ M Mode]
  • RVFAC (RV Fractional Area Change) normal is >35% [measured in AP4C]
• Diastolic function measured with tissue doppler:
  • Tricuspid annulus (E) and early diastolic tricuspid inflow (E’) ratio (E/E’) measured in patients with PH
• Can be difficult to assess due to shape, trabeculations
• May require TOE
• RWMA is sensitive and specific for RV ischaemia or infarction

PULMONARY ARTERY SYSTOLIC PRESSURE (PASP)

• some TR is normal
• In the absence of RVOT obstruction: RVSP = PASP
• RV systolic pressure = RAP + transtricuspid gradient (from peak tricuspid regurgitation velocity)

OTHER

• TAPSE / PASP ratio may be a good marker of RV-PA coupling (or uncoupling) as TAPSE reflects RV contractile function and PASP is a surrogate for afterload
  • TAPSE/PASP ratio normally >0.31mm/mmHg
  • A ratio of <0.31mm/mmHg was predictive of patients having a significantly worse prognosis than those with higher ratios

RV DILATION MAY BE DUE TO:

• Acute or Chronic RV Failure
• Large PE
• Pulmonary Hypertension
• Volume Overload
• TR (leading to volume overload) –> ‘auto-aggravation’
• ASD
• PR / PS
• RV myocardial infarction

ECHO FEATURES OF RV FAILURE

• RV dilation (can grossly compare w/ LV size on AP4C)
• Diastolic interventricular septal flattening (left-ward shift) = volume overloaded state
• Systolic interventricular flattening (left-ward shift) = pressure overloaded state
• RV hypokinesis (mild, moderate, severe)
• Hepatic vein flow reversal indicates severe TR
• Left-ward interatrial septal bowing also indicates increased RAP / volume overload
• IVC diameter / collapsibility with respiration (or lack thereof) may be indicator of volume overload

References and Links

• Burgess MI, Bright-Thomas RJ, Ray SG. Echocardiographic evaluation of right ventricular function. Eur J Echocardiogr. 2002 Dec;3(4):252-62. PMID: 12413440. [Free Fulltext]
• ICU Sonography — Assessment of the right heart
• Konstam MA, Kiernan MS, Bernstein D, Bozkurt B, Jacob M, Kapur NK, Kociol RD, Lewis EF, Mehra MR, Pagani FD, Raval AN, Ward C; American Heart Association Council on Clinical Cardiology; Council on Cardiovascular Disease in the Young; and Council on Cardiovascular Surgery and Anesthesia. Evaluation and Management of Right-Sided Heart Failure: A Scientific Statement From the American Heart Association. Circulation. 2018 May 15;137(20):e578-e622. doi: 10.1161/CIR.0000000000000560. Epub 2018 Apr 12. PMID: 29650544. [Free Full Text]

[cite]