Body surface isopotential T map for assessment of right ventricular volume and pressure overloads in secundum atrial septal defect

The body surface isopotential T map was analyzed to detect right ventricular volume and pressure overloads in 25 patients with secundum atrial septal defect. Three patterns were distinguished: a T map resembling normal (type A,n=9); that with an isolated negative area in a positive area (type B,n=11); and that with rightward movement of maximum (type C,n=5). Right ventricular end-diastolic volumes in types B (161±19% of normal; %N) and C (175±40%N) were significantly (p<0.01) greater than those in controls (100±9%N) and type A (113±18%N). Right ventricular systolic pressure in type C (48±11 mmHg) was significantly (p<0.01) higher than those in the controls (30±5 mmHg), type A (31±4 mmHg), or type B (34±5 mmHg). These results suggest that the patients with type B have right ventricular volume overload and those with type C have both volume and pressure overloads.