P-wave indices in patients with pulmonary emphysema: do P-terminal force and interatrial block have confounding effects?

Figures & data

Figure 1 (A and B) Schematic illustration of how to calculate Ptf.

Notes: (A) Biphasic P-wave in V₁. (B) Full negative P-wave in V₁.
Abbreviation: s-Ptf, significant P-terminal force.

Table 1 Incidence of IAB, s-Ptf and type of P-wave morphology in lead V1 in emphysema patients based upon the presence of vertical or non-vertical P-vector

Variable	Vertical P-axis (>60°)	Nonvertical P-axis (≤60°)	Total (n)	P-value
Emphysema patients	125 (71%)	51 (29%)	176 (100%)	–
IAB	45 (36%)	24 (47%)	69 (39.2%)	0.23
s-Ptf	73 (58.4%)	20 (39.2%)	93 (52.8%)	0.03
P (−) V1	55 (71.4%)	12 (60%)	67 (65%)	0.28
P (+/−) V1	18 (24.6%)	8 (40%)	26 (25%)

Abbreviations: s-Ptf, significant P-terminal force; IAB, interatrial block; P (−) V₁, fully negative P-wave in lead V₁; P (+/−) V₁, biphasic P-wave morphology in lead V₁.

Figure 2 Schematic illustration of the incidence of interatrial block (IAB) and significant P-terminal force (s-Ptf) in emphysema patients.

Abbreviations: IAB, Interatrial block; s-Ptf (+), presence of significant P-terminal force; s-Ptf (−), absence of significant P-terminal force.

Figure 3 Distribution of types of P-terminal force (Biphasic vs. Fully negative) based on the presence or absence of interatrial block.

Abbreviations: IAB, interatrial block; s-Ptf, significant P-terminal force.

Figure 4 Electrocardiogram of a patient with emphysema.

Notes: Vertical P-vector and P pulmonale is present. Note the presence of a fully negative P-wave in V1 with significant P-terminal force (approximately 80 mm.ms). Based on the presence of P pulmonale and suspected right atrial strain/enlargement, one should expect a tall initial positive P-component in V1, which is in fact absent, suggesting primary contribution of diaphragmatic flattening and right atrial anatomical distortion to the generation of vertical P-vector.