What is a normal right ventricular internal diameter at diastole (RVIDD)?

Normal Right Ventricular Internal Diameter at Diastole (RVIDD)

The normal right ventricular internal diameter at diastole (RVIDD) measured at the basal level is ≤41 mm, with a mid-cavity measurement ≤35 mm, according to current echocardiographic guidelines. 1

Normal RV Dimensions by Location

• The normal range for RV basal diameter (measured as the maximal transversal dimension in the basal one-third of RV inflow at end-diastole in the RV-focused view) is 25-41 mm, with a mean of 33 ± 4 mm 1
• The normal range for RV mid-diameter (measured at the middle third of RV inflow) is 19-35 mm, with a mean of 27 ± 4 mm 1
• The normal range for RV longitudinal diameter is 59-83 mm, with a mean of 71 ± 6 mm 1

Measurement Technique

• RVIDD should be measured from the RV-focused apical four-chamber view, which provides better visualization of the entire RV free wall than the standard four-chamber view 1
• Measurements should be taken at end-diastole using the inner-edge-to-inner-edge method 1
• The basal RV diameter should be measured as the maximal transversal dimension in the basal one-third of the RV inflow 1
• The mid-cavity RV diameter should be measured approximately halfway between the maximal basal diameter and the apex, at the level of papillary muscles 1

Clinical Significance

• Values exceeding 41 mm at the base or 35 mm at the mid-level indicate RV dilatation 1
• In patients with tricuspid regurgitation (TR), RV dimensions are important for assessing severity - a mid-RV dimension ≤33 mm is considered a cut-off value for non-significant right-sided chamber enlargement 1
• In arrhythmogenic cardiomyopathy (AC), RV dimensions are part of the diagnostic criteria, with specific thresholds for major and minor criteria 1

Additional Considerations

• RV size assessment should include both qualitative and quantitative parameters from multiple acoustic windows 1
• Linear measurements may underestimate true RV size due to its crescent shape 1
• RV dimensions are dependent on probe rotation and different RV views; the echocardiography report should state the window from which the measurement was performed 1
• When available, 3D echocardiographic measurements of RV volumes provide more comprehensive assessment of RV size 1
• Normal RV end-diastolic area is ≤28 cm², with a normal RV end-systolic area ≤16 cm² 1

Gender Differences

• There are gender-specific differences in RV size, with males typically having larger RV dimensions than females of similar age 2
• For RV end-diastolic area, values >24.7 cm² for men and >20.7 cm² for women represent the 97.5th percentile of normal values 2

Pitfalls in Measurement

• RV size may be underestimated if the RV cavity is foreshortened 1
• Due to LV twisting motion and the crescent RV shape, the end-diastolic RV image may not be in the same tomographic plane as the end-systolic one 1
• Linear dimensions may not accurately reflect global RV size and can lead to underestimation or overestimation 1
• Proper attention to imaging technique is essential for accurate measurements 1