From the Guidelines
A respiratory variation in the tricuspid regurgitation (TR) gradient greater than 50% is considered a normal physiological phenomenon. This finding is a common occurrence that happens due to the influence of respiration on right heart hemodynamics, as described in the 2014 AHA/ACC guideline for the management of patients with valvular heart disease 1. During inspiration, negative intrathoracic pressure increases venous return to the right heart, which can temporarily increase the TR gradient. Conversely, during expiration, the TR gradient typically decreases. This normal respiratory variation reflects the right ventricle's sensitivity to changes in preload and is an expected finding during echocardiographic assessment. Some key points to consider when evaluating TR include:
- The integrative assessment of multiple parameters to characterize the severity of TR, as recommended by the ASE and EAE 1
- The measurement of tricuspid annular diameter in the apical 4-chamber view to distinguish primary from functional TR 1
- The estimation of pulmonary artery systolic pressure from the maximal tricuspid valve regurgitant velocity 1 Clinicians should be concerned only when this variation occurs alongside other abnormal findings such as right ventricular dilation, elevated right atrial pressure, or signs of right heart failure, as outlined in the stages of TR (Table 19) 1. Understanding this normal physiological response helps avoid misinterpretation of TR measurements and prevents unnecessary additional testing or interventions based solely on respiratory TR gradient variations.
From the Research
Respiratory Variation in TR Gradient
- The concept of respiratory variation in tricuspid regurgitation (TR) gradient is supported by a study published in 2010 2, which found that expiration to inspiration changes affected TR peak velocity, duration, and time-velocity integral.
- The study demonstrated that inspiratory TR augmentation was characterized by increased effective regurgitant orifice and volume, despite a decreased TR driving force.
- The pathophysiology of TR is complex and dynamic, with almost universal respiratory changes of large magnitude, as noted in the 2010 study 2.
Clinical Implications
- A respiratory variation in the TR gradient of greater than 50% may be considered abnormal, as it suggests that the TR is influenced by changes in respiration, which is consistent with the findings of the 2010 study 2.
- The diagnosis and treatment of TR, including the assessment of respiratory dependence, are crucial in managing the disease, as highlighted in studies published in 2022 3 and 2023 4.
- Transcatheter therapies, such as edge-to-edge repair, are emerging as promising solutions for patients with severe TR, as discussed in studies published in 2017 5 and 2022 6.
Key Findings
- The 2010 study 2 found that effective regurgitant orifice changes during inspiration were independently linked to inspiratory annular enlargement and right ventricular shape widening with increased valvular tenting.
- The study published in 2022 6 emphasized the importance of understanding the valvular/ventricular anatomy and disease pathophysiology in determining appropriate management solutions for TR.
- The 2023 study 4 highlighted the need for detailed morphological and mechanistic assessment of the tricuspid valve using transthoracic and transesophageal imaging to optimize patient selection and procedural success for transcatheter edge-to-edge repair.