Right Atrial Enlargement

Gregory Kicska, MD, PhD

DIFFERENTIAL DIAGNOSIS

Common

Secondary Causes of Right Ventricle Enlargement
Tricuspid Valve Disease
Chronic Atrial Fibrillation

Less Common

Left to Right Shunt

Rare but Important

Right Atrial Mass
Ebstein Anomaly

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Radiograph shows rightward displacement of right-lower heart contour
End diastolic volume (maximum volume) > 90 mL/m² highly specific for enlargement

Helpful Clues for Common Diagnoses

Secondary Causes of Right Ventricle Enlargement
- Pulmonary hypertension suggested by aorta:PA ratio < 1:1 or main PA > 2.9 cm
- Failure suggested by coexistent coronary artery disease
Tricuspid Valve Disease
- Regurgitation commonly due to myxomatous degeneration, rheumatic heart disease in older population
- Increased serotonin levels in carcinoid syndrome can generate fibrous tricuspid leaflet plaques that cause regurgitation
Chronic Atrial Fibrillation
- Diagnosis suggested by ECG abnormality
- Right atrial appendage should be examined for thrombus

Helpful Clues for Less Common Diagnoses

Left to Right Shunt
- MR PA: aorta flow ratio > 1
- Atrial septal defect (ASD)
  - MR bright-blood cine likely to show flow jet except in large ASD
- Ventricular septal defect (VSD)
  - Most common left to right shunt but often not hemodynamically significant or spontaneously closes by adulthood
- Partial anomalous pulmonary venous return
  - Most commonly from right upper lobe to SVC seen best on CT or MRA

Helpful Clues for Rare Diagnoses

Right Atrial Mass
- Myxoma: Soft, pliable mass, connected to interatrial septum by thin stalk
- Most often intermediate low T1-weighted signal, high T2-weighted signal
Ebstein Anomaly
- Apical displacement of septal and posterior tricuspid leaflets with atrialization of proximal right ventricle
- Coexistent tricuspid regurgitation and stenosis common

Image Gallery

Axial enhanced CT shows RA

and RV

enlargement due to primary pulmonary hypertension and right heart failure. Left heart function is normal. On this admission, patient presented with atrial fibrillation.

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