Usefulness of QRST isointegral maps for the diagnosis of right ventricular pressure overload in patients with surgically repaired tetralogy of Fallot complicated by right bundle block.

Right ventricular pressure overload was evaluated in 29 patients, 8-12 years old, with surgically repaired tetralogy of Fallot by using body surface QRST isointegral maps. In patients with right ventricular systolic pressure above 50 mmHg, the maxima of the isointegral maps tended to shift toward the lower right-hand region of the map. The maximum value was significantly correlated with right ventricular systolic pressure (r = .58; P < .01). There was a correlation between the right ventricular systolic pressure and the percentage +2SD and percentage +5SD departure areas, which are defined as the area (expressed as a percentage of the total chest area) in which the QRST integral values are greater than the normal mean +2SD or +5SD, respectively (r = .61 and .84, P < .01). The QRST isointegral map can be used to evaluate right ventricular pressure overload in postoperative patients with tetralogy of Fallot complicated by right bundle branch block. The percentage +5SD departure area is the most valuable parameter for the quantitative evaluation of the right ventricular systolic pressure.