Assessment of the Inferior Vena Cava and Right Atrial Pressure on Echocardiography
Anatomical Landmarks of the IVC
The inferior vena cava (IVC) is a collector of deoxygenated blood from the lower half of the body and the abdominal cavity, accompanying the aorta, located to its right and anterior to the spine. At the junction between the IVC and the right atrium is the Eustachian valve (EV); its remnants, visualized on echocardiography, are considered a normal finding (Blagodir, 2024).
Normal IVC Dimensions
The normal diastolic diameter of the inferior vena cava is 12–21 mm (Blagodir, 2024). Significant elevation of filling pressure in the right heart is unlikely with normal RV and RA sizes, normal IVC size with inspiratory collapse, and normal thickness of the RV free wall (BSE, 2020).
Criteria for Increased Pressure and Probability of PH
According to BSE (2018) recommendations, the assessment of the probability of pulmonary hypertension includes signs from the IVC and right atrium:
| Parameter | Threshold Value (BSE, 2018) |
|---|---|
| IVC Diameter | >21 mm with reduced inspiratory collapse (<50% during sniff or <20% during quiet breathing) |
| Right Atrial Area (end-systole) | >18 cm² |
| Ratio of Basal RV/LV Diameters | >1.0 |
IVC Assessment in the Context of Volume Status
IVC measurement is also used to assess intravascular volume, including portable ultrasound examination, and correlates with prognostic markers in heart failure decompensation (Brennan et al.; Goonewardena et al.). Historical studies describe non-invasive RAP assessment by IVC inspiratory collapse (Kircher et al.) and the impact of ventilation on IVC configuration (Jue et al.; Natori et al.).
Practical Views
Assessment of the right heart and IVC is part of the two-dimensional morphological evaluation of the right heart (BSE, 2020). In the parasternal short-axis view at the base of the heart (SAX BASE), the coronary sinus (CS), Eustachian valve (EV), IVC, SVC, tricuspid valve (TV), and other right heart structures are visualized (Blagodir, 2024).
Frequently asked questions
What is the normal diameter of the IVC?
The normal diastolic diameter of the inferior vena cava is 12–21 mm (Blagodir, 2024).
What IVC diameter indicates increased pressure and probability of PH?
An IVC diameter >21 mm with reduced inspiratory collapse (<50% during sniff or <20% during quiet breathing) (BSE, 2018).
What is the threshold for right atrial area used as a sign of PH?
Right atrial area at end-systole >18 cm² (BSE, 2018).
When is increased filling pressure in the right heart unlikely?
With normal RV and RA sizes, normal IVC size with inspiratory collapse, and normal thickness of the RV free wall (BSE, 2020).
In which view are the IVC and Eustachian valve visualized?
In the parasternal short-axis view at the base of the heart (SAX BASE), the IVC, Eustachian valve, SVC, coronary sinus, and tricuspid valve are visualized (Blagodir, 2024).