1979 Volume 43 Issue 10 Pages 934-944
The first purpose of this study was to determine which P wave features contain information to distinguish between right atrial pressure overloading (RAPO) and volume overloading (RAVO) and then to lean whether this discrimination can be diagnostically significant. We then attempted, using correlational and multi-variate analytical methods, to extend this diagnostic utilization of the orthogonal P wave to hemodynamic parameters. Forty-nine patients with isolated pulmonary stenosis (PS) or primary pulmonary hypertension (PH), and 44 patients with ostium secundum atrial septal defect (ASD) were used as prototypes for RAPO and RAVO, respectively. In the relationship between 97 computer-measured P wave items and selected hemodynamic variables, "magnitude of maximal P vector in the horizontal plane" showed the highest correlation with right ventricular systolic pressure (sys. RVP) in RAPO (r=0.75) and with the shunt ratio in RAVO (r=0.69), (both significant at p < 0.001). A stepwise multiple regression analysis using several P wave measurements was also attempted to predict the sys. RVP or the shunt ratio. To determine the maximum number of P wave items (singly or in combination) useful in separation of RAPO and RAVO, multi-variate statistical analysis was performed. The chosen combination of azimuth of terminal 30 msec. P vector, angle of maximal P vector in the horizontal plane resulted in correct identification of 78% of RAPO and 77% RAVO. Thus the terminal P wave components representing left atrial activity prove important in differentiating between RAPO and RAVO.
