From the Guidelines
The respiratory variation in the tricuspid valve is measured with Doppler echocardiography, specifically using the diameter and respiratory variation in diameter of the inferior vena cava (IVC) to estimate right atrial pressure (RAP) 1. This method is based on the simplified Bernoulli equation, which describes the relationship between tricuspid regurgitation velocity and the peak pressure gradient of tricuspid regurgitation.
- The estimation of RAP is crucial in calculating the peak tricuspid regurgitation velocity and subsequently estimating the pulmonary artery systolic pressure.
- The diameter and respiratory variation of the IVC are used to estimate RAP, with an IVC diameter <2.1 cm that collapses >50% with a sniff suggesting a normal RA pressure of 3 mmHg, and an IVC diameter >2.1 cm that collapses <50% with a sniff or <20% on quiet inspiration suggesting a high RA pressure of 15 mmHg 1.
- This approach is recommended by the European Association of Cardiovascular Imaging (EACVI) and is used to assign a level of probability of pulmonary hypertension (PH) based on the tricuspid regurgitation velocity and other echocardiographic variables 1. The most recent and highest quality study supporting this method is the 2015 ESC/ERS guidelines for the diagnosis and treatment of pulmonary hypertension 1.
From the Research
Respiratory Variation in Tricuspid Valve
- The respiratory variation in the tricuspid valve is measured by Doppler echocardiography, which assesses the changes in tricuspid regurgitation systolic velocities during spontaneous respiration 2.
- The difference between the maximal (expiratory) and minimal (inspiratory) tricuspid regurgitation systolic velocities is used to diagnose severe tricuspid regurgitation, with a difference of ≥0.6 m/s having a sensitivity of 66% and specificity of 94% 2.
- Respiratory changes in tricuspid regurgitation velocities are also associated with signs of more severe tricuspid regurgitation, such as greater right ventricular size and malcoaptation of the tricuspid valve leaflets 2.
Measurement Techniques
- Doppler echocardiography is used to measure tricuspid regurgitation velocities, with the "chin" measurement being more accurate than the "beard" measurement for estimating right ventricular systolic pressure and pulmonary vascular resistance 3.
- The feasibility of measuring tricuspid regurgitation velocity and pulmonary flow acceleration time during exercise stress echocardiography is also assessed, with the latter being more feasible and closely correlated with invasive pulmonary artery systolic pressure 4.
Clinical Implications
- The assessment of respiratory variation in the tricuspid valve has clinical implications for the diagnosis and management of tricuspid regurgitation, pulmonary hypertension, and cardiac tamponade 2, 5, 3, 4, 6.
- The use of Doppler echocardiography and measurement of tricuspid regurgitation velocities can help identify patients with severe tricuspid regurgitation and guide treatment decisions, such as tricuspid valve repair or replacement 2, 5.