What is the significance of a 50% variation in Respiratory Variation (RESP) on the tricuspid valve?

From the Guidelines

Respiratory variation of 50% in the tricuspid valve flow is considered within the upper limit of normal and does not necessarily require intervention, unless accompanied by symptoms or signs of right heart failure. This phenomenon is a result of normal physiology, where negative intrathoracic pressure during inspiration increases venous return to the right heart, enhancing right ventricular filling and increasing tricuspid flow, and reduced venous return during expiration decreases tricuspid flow 1. The tricuspid valve typically shows respiratory variation of 25-50% in healthy individuals, with increased flow during inspiration and decreased flow during expiration. However, if the patient has symptoms like shortness of breath, fatigue, or signs of right heart failure, further cardiac evaluation would be warranted, including echocardiographic assessment to evaluate right ventricular size and function, tricuspid valve morphology, and estimation of pulmonary pressures to rule out conditions like pulmonary hypertension or tricuspid regurgitation that might be associated with exaggerated respiratory variation 1. Some key points to consider in the evaluation of tricuspid valve disease include:

• The presence of concomitant pulmonary valve disease, which can accelerate RV remodelling and may not always improve after treatment of the upstream regurgitant lesion 1
• The use of multi-modality imaging, including echocardiography, CMR, and CT, to assess tricuspid valve and pulmonary valve morphology and function, as well as right chamber size and function 1
• The importance of considering the patient's overall clinical context, including symptoms and signs of right heart failure, when determining the need for intervention. According to the most recent guidelines, tricuspid valve surgery is recommended for patients with severe TR undergoing left-sided valve surgery 1.

From the Research

Tricuspid Valve Regurgitation

• Tricuspid regurgitation (TR) is a common condition, affecting approximately 1.6 million individuals in the United States and 3.0 million people in Europe 2.
• The condition can be primary or secondary, with secondary TR being the most prevalent, resulting from maladaptive right ventricular remodeling secondary to pulmonary hypertension or atrial fibrillation 3.

Diagnosis and Severity Grading

• Echocardiography can assess TR etiology and severity, measure right atrial (RA) and right ventricular (RV) size and function, estimate pulmonary pressure, and characterize left ventricular disease 2.
• The effective regurgitant orifice (ERO) is used to quantify TR severity, with an ERO ≥0.4 cm2 indicating severe TR 4.

Management and Treatment

• Management of TR includes diuretics, ACE inhibitors, and aldosterone antagonists 2.
• Surgical annuloplasty or valve replacement should be considered in patients with progressive RV dilatation without severe left ventricular dysfunction and pulmonary hypertension 2.
• Transcatheter repair or replacement is an emerging therapy for high-risk patients with TR who would otherwise have a dismal clinical prognosis 2, 3, 5.

Clinical Presentation and Outcome

• TR is associated with worsening prognosis, regardless of the underlying etiology, and should be addressed as a separate therapeutic target 3.
• Severe TR (ERO ≥0.4 cm2) is associated with increased mortality and cardiac events, including heart failure and new atrial fibrillation 4.