P Tricuspidale

P Tricuspidale

Notched P wave in lead II with the first peak taller than the second, indicates biatrial enlargement and has been called ‘P tricuspidale’ [1,2]. The original description of ‘P tricuspidale’ was by Zuckermann R et al in 1952 [3]. The pattern is a mirror image of the ‘P mitrale‘ in which the second peak is taller. P tricuspidale was noted by Gamboa R and associates in 81 percent of their thirty seven patients with tricuspid atresia, while it was seen in only two of their twenty patients with pulmonary atresia [1]. In P tricuspidale, the taller initial peak is the right atrial component and the second wider peak is the left atrial component. That is how it indicates biatrial enlargement with preponderance of right atrium.

It may be noted that in pure left atrial enlargement the P wave in lead II is widened, usually with a notch separating the right and left atrial components, but the amplitude of the P wave is within the normal range. In P tricuspidale, both amplitude and duration of the P wave is increased, due to biatrial enlargement. The upper limit of normal width of P wave is 100 milliseconds (2.5 millimeters with a recording speed of 25 millimeters per second). The upper limit of normal P wave amplitude is also 2.5 millimeters (with a standardization of 10 millimeters per millivolt) or 0.25 millivolts.

References

1. Gamboa R, Gersony WM, Nadas AS. The electrocardiogram in tricuspid atresia and pulmonary atresia with intact ventricular septum. Circulation. 1966 Jul;34(1):24-37.
2. Chugh SN. Textbook of Clinical Electrocardiography. Jaypee Brothers Publishers. Page 78.
3. Zuckermann R, Cisneros F, Novelo S. El electrocardiograma en 21 topos diferentes de cardiopatias congenitas. Arch Inst Cardiol Mex 22: 550, 1952 (Cited by Gamboa R et al [1]).