From the Guidelines
Respiratory variation in the tricuspid valve is characterized by increased flow velocities and a wider opening of the valve during inspiration, and decreased flow velocities during expiration, with a normal increase in tricuspid inflow velocities of 25-50% during inspiration compared to expiration 1.
Normal Physiological Changes
The tricuspid valve exhibits normal physiological changes in blood flow during the respiratory cycle, with increased venous return to the right side of the heart during inspiration, resulting in increased tricuspid valve flow velocities and a wider opening of the valve. Conversely, during expiration, there is decreased venous return, leading to reduced flow velocities across the tricuspid valve.
Clinical Observations
Clinically, this normal respiratory variation can be observed during echocardiography, where tricuspid inflow velocities typically increase by 25-50% during inspiration compared to expiration 1. Exaggerated respiratory variation (>40%) may indicate constrictive pericarditis or cardiac tamponade, while diminished variation might suggest right ventricular dysfunction or severe tricuspid regurgitation.
Pathological States
Understanding this normal physiological phenomenon helps clinicians accurately interpret echocardiographic findings and distinguish normal from pathological states, such as severe tricuspid regurgitation, which can be graded using parameters such as tricuspid valve morphology, colour flow TR jet, CW signal of TR jet, and semi-quantitative and quantitative measures, including VC width, PISA radius, hepatic vein flow, and tricuspid inflow 1.
Grading Tricuspid Regurgitation
The severity of tricuspid regurgitation can be graded using the parameters outlined in Table 9 of the European Association of Cardiovascular Imaging guidelines, which include qualitative, semi-quantitative, and quantitative measures, such as tricuspid valve morphology, colour flow TR jet, CW signal of TR jet, VC width, PISA radius, hepatic vein flow, and tricuspid inflow 1.
From the Research
Respiratory Variation in Tricuspid Valve
- The respiratory variation in the tricuspid valve is characterized by changes in tricuspid regurgitation (TR) systolic velocities during spontaneous respiration 2.
- Studies have shown that excessive respiratory changes in TR velocities are diagnostic of severe TR, with a difference in TR velocity ≥0.6 m/s having a sensitivity of 66% and specificity of 94% for diagnosing severe TR 2.
- The respiratory differences in TR velocities were greater in patients with severe TR (0.72 ± 0.30 m/s), compared with patients with moderate TR (0.28 ± 0.18; P < 0.001) 2.
Diagnostic Value
- The diagnostic value of the respiratory changes in TR velocity for detecting severe TR was assessed using receiver-operating characteristics analysis, with an area under the curve of 0.92 (95% confidence interval: 0.87-0.96; P < 0.001) 2.
- Excessive values of TR velocity difference were associated with signs of more severe TR, including greater right ventricular size and malcoaptation of the tricuspid valve leaflets 2.
Comparison with Other Conditions
- Tricuspid regurgitation can be differentiated from constrictive pericarditis using haemodynamic parameters, including relative changes in left ventricular (LV) and right ventricular (RV) diastolic pressures during respiration 3.
- During inspiration, the difference between the LV and RV diastolic pressures widened in patients with severe tricuspid regurgitation, but narrowed in patients with constrictive pericarditis 3.