SQUARE ROOT SIGN OF LEFT-VENTRICULAR DIASTOLIC PRESSURE CURVE IN ATRIAL SEPTAL-DEFECT

The square root (dip and plateau) sign was observed in 7 of 21 adult patients with atrial septal defect (ASD). This study evaluated left ventricular (LV) diastolic filling dynamics and hemodynamic findings in 7 patients (Group 1) with, and 14 patients (Group 2) without the square root sign; 10 normal subjects (Group 3) served as controls. No significant differences were observed in LV end-diastolic and end-systolic volumes, ejection fraction, or left to right shunt. In Group 1, 77% of LV filling was completed in the first half of diastole; this percentage was 49% and 53% in Groups 2 and 3, respectively (both p < 0.01 versus Group 1). Early diastolic filling velocity (at 20% of diastole) in Group 1 was significantly greater, and late diastolic filling velocity (at 80% and 90% of diastole) was reduced in Group 1 compared to those in Groups 2 and 3 (all p < 0.05). The average values for right and left ventricular end-diastolic pressures were significantly higher in Group 1 (11 +/-2 and 10 +/- mmHg, p < 0.05) than Group 2 (7 +/- 2 and 7 +/- 2 mmHg, p < 0.05). It is suggested that a constrictive pathophysiology due to 4 chambers interaction or right ventricular constraint may play a role in the genesis of the square root sign in ASD.