Tricuspid regurgitation (TR) is one of those Step-style valve lesions that seems “low drama” until you realize how often it’s hiding behind right-sided heart failure, IV drug use, pulmonary HTN, or a carcinoid tumor stem. The good news: TR is extremely pattern-based. If you lock in who gets it, why JVP looks weird, and what gets louder with inspiration, you’ll pick up easy points.
Where Tricuspid Regurgitation Fits (Big Picture)
Definition: TR is backflow from the right ventricle (RV) into the right atrium (RA) during systole due to failure of the tricuspid valve to coapt.
Step 1 framing: Think volume overload of RA/RV → systemic venous congestion (JVD, hepatomegaly, ascites, edema).
First Aid cross-reference (concepts):
- Murmurs & maneuvers: Right-sided murmurs increase with inspiration (Carvallo sign).
- Infective endocarditis: IV drug use → tricuspid valve (often S. aureus).
- Carcinoid syndrome: Serotonin-mediated fibrous deposits on right-sided valves.
- Pulmonary HTN / cor pulmonale: Functional TR due to RV dilation.
Anatomy & Physiology Refresher (Why the Murmur Changes with Breathing)
Inspiration decreases intrathoracic pressure → increases venous return to the right heart → increases flow across the tricuspid valve → right-sided murmurs get louder.
- TR intensity ↑ with inspiration (Carvallo sign)
- Handgrip generally increases regurgitant murmurs overall (↑ afterload), but the most testable maneuver for TR is inspiration.
Etiology: The High-Yield Causes (Know “Primary” vs “Functional”)
Most TR on exams is functional (secondary), not primary leaflet disease.
1) Functional (Secondary) TR — Most Common
Due to tricuspid annular dilation from RV enlargement.
Classic causes:
- Pulmonary hypertension (e.g., COPD, chronic thromboembolic disease, OSA)
- Left-sided heart failure → pulmonary venous HTN → pulmonary arterial HTN → RV dilation
- RV infarct or cardiomyopathy → RV dilation
Board clue: TR in a patient with signs of pulmonary HTN or cor pulmonale is usually functional.
2) Primary (Structural) TR — Know These Associations
- Infective endocarditis (IV drug use)
- Common organism: Staphylococcus aureus
- Stems may include fever, septic pulmonary emboli, new murmur
- Carcinoid syndrome
- Serotonin → plaque-like fibrosis of tricuspid valve (and pulmonic valve)
- Clues: flushing, diarrhea, wheezing, ↑ urinary 5-HIAA
- Rheumatic heart disease (less common for tricuspid; usually mitral ± aortic)
- Congenital: Ebstein anomaly (tricuspid valve displacement) → TR + “atrialized” RV
- Iatrogenic: pacemaker/ICD lead-induced TR
Pathophysiology (Step 1 Mechanism Chain)
During systole, blood regurgitates from RV → RA, leading to:
- RA volume overload → RA dilation → increased RA pressure
- Systemic venous congestion (because RA backs up into vena cava system)
- RV volume overload (regurgitant volume returns to RV in diastole) → RV dilation
- Over time: right-sided heart failure features predominate
Hemodynamic consequences:
- Elevated JVP
- Reduced effective forward flow into the pulmonary circulation (can contribute to fatigue/exercise intolerance)
Clinical Presentation: What TR “Looks Like” on the Wards (and on Step)
Symptoms (often right-sided HF symptoms)
- Fatigue, weakness (low forward output)
- Abdominal fullness, RUQ discomfort (hepatic congestion)
- Peripheral edema, ascites
Signs (high-yield)
- Holosystolic murmur best heard at left lower sternal border
- Louder with inspiration (Carvallo sign)
- JVD with prominent v waves
- Why v waves? Regurg into RA during systole increases RA pressure during the “v wave” phase.
- Pulsatile hepatomegaly
- Ascites, peripheral edema
JVP waveform: the exam favorite
| Lesion | JVP finding | Mechanism |
|---|---|---|
| Tricuspid regurgitation | Prominent v waves | Systolic regurg into RA increases RA pressure during v wave |
| Tricuspid stenosis | Prominent a waves | Increased resistance to RA emptying into RV |
How to Diagnose TR (What Tests Show)
Auscultation
- Holosystolic blowing murmur at LLSB
- Increase with inspiration
Echocardiography (best test)
Echo is the key diagnostic tool and helps define:
- Severity of regurgitation
- Valve morphology (vegetations? carcinoid plaques?)
- RV size/function
- Pulmonary pressures (estimate pulmonary HTN)
ECG / CXR (supportive, not definitive)
- ECG: RA enlargement (peaked P waves), RV hypertrophy depending on cause
- CXR: cardiomegaly; may show pulmonary HTN signs if present
Differential Diagnosis: Don’t Confuse These Holosystolic Murmurs
| Lesion | Murmur location | Radiation | Maneuver that increases intensity |
|---|---|---|---|
| Tricuspid regurgitation | LLSB | Often minimal | Inspiration |
| Mitral regurgitation | Apex | Axilla | Handgrip |
| VSD | LLSB | Often none | Handgrip |
| Tricuspid regurg vs VSD (tip) | TR often with JVD, hepatomegaly, pulsatile liver | — | TR gets louder with inspiration |
Stem trick: If they give you IV drug use + holosystolic murmur at LLSB + JVD, they’re practically handing you TR due to endocarditis.
Treatment (Step-Relevant Approach)
Treatment depends on cause and severity.
1) Treat the underlying driver (especially functional TR)
- Pulmonary HTN management (oxygen for hypoxia, treat COPD/OSA, anticoagulation for CTEPH as appropriate)
- Optimize left-sided HF (diuretics, guideline-directed therapy)
- Diuretics for volume overload symptoms (edema, ascites)
2) If primary TR due to endocarditis
- IV antibiotics tailored to organism (empiric coverage often targets S. aureus in IVDU)
- Consider surgery if:
- Persistent bacteremia
- Large vegetations with recurrent emboli
- Severe valve dysfunction causing HF
3) Surgical/Interventional options (conceptual for exams)
- Valve repair preferred when feasible (annuloplasty)
- Valve replacement if repair not possible
- Indications trend around severe symptomatic TR, progressive RV dilation/dysfunction, or when doing left-sided valve surgery and TR is significant.
High-Yield Associations & “Buzz Phrases” (USMLE Gold)
TR + IV Drug Use
- Most common valve in IVDU endocarditis: tricuspid
- Most common organism: S. aureus
- Clue: septic pulmonary emboli (because right heart → lungs)
TR + Carcinoid Syndrome
- Carcinoid typically affects right-sided valves because serotonin is inactivated in the lungs.
- Expect TR and/or pulmonic regurg/stenosis
- Clues: flushing, diarrhea, bronchospasm, ↑ 5-HIAA
TR + Pulmonary Hypertension
- Functional TR from RV dilation
- Look for loud P2, RV heave, signs of cor pulmonale
Auscultation one-liner
- “TR = holosystolic at LLSB, louder with inspiration, prominent v waves in JVP.”
Quick Step 1 Memory Anchors
- Right-sided murmurs get louder with inspiration
- TR → prominent v waves
- Functional TR is most common (annular dilation from RV enlargement)
- IVDU endocarditis loves the tricuspid valve (S. aureus)
- Carcinoid → right-sided valves (tricuspid ± pulmonic)
Mini Self-Check (3 Rapid Questions)
-
A holosystolic murmur at the left lower sternal border gets louder when the patient inhales deeply. Most likely lesion?
Tricuspid regurgitation. -
Which JVP waveform abnormality is most associated with TR?
Prominent v waves. -
IVDU + fever + lung infarct-like findings + new murmur at LLSB: likely organism and valve?
S. aureus on the tricuspid valve.