RA chamber size (longest diameter; not including vena cava): <7 cm

• Measure transverse perpendicular to interatrial septum from septal wall to lateral wall

• Enlarged >=7.0 cm; tricuspid regurgitation, pulm HTN, congenital heart defect (ASD)

RV chamber size (short axis diameter) <5.5 cm

• Measure transverse diameter perpendicular to IV septum, from septal to free wall.

• RV:LV diameter ratio (cutoff of 1.0) is used to define RV dysfunction. 

• Enlarged >/= 5.5 cm

• Wall size: 7mm

LA chamber size (longest AP diameter; avoid pulmonary veins) <4.5 cm

• Measure greatest AP dimension at level of Ao root in axial images

• Enlarged >= 4.5 cm; mitral/Ao valve dz, CHF, diastolic dysfunction and atrial fibrillation.

LV chamber size (short axis diameter; end diastolic) <5.5 cm

• Measure simple transverse diameter at the mid-ventricular level, perpendicular to the interventricular septum from septal to lateral wall.

• Enlarged >= 5.5 cm; mitral and Ao valve dz, ischemic heart dz, HF (dilated and nonischemic)

• LV wall size 12 mm