Optimal electrocardiographic limb lead set for rapid emphysema screening

Abstract

BackgroundPulmonary emphysema of any etiology has been shown to be strongly and quasidiagnostically associated with a vertical frontal P wave axis. A vertical P wave axis (>60 degrees) during sinus rhythm can be easily determined by a P wave in lead III greater than the P wave in lead I (bipolar lead set) or a dominantly negative P wave in aVL (unipolar lead set). The purpose of this investigation was to determine which set of limb leads may be better for identifying the vertical P vector of emphysema in adults.MethodsUnselected consecutive electrocardiograms from 100 patients with a diagnosis of emphysema were analyzed to determine the P wave axis. Patients aged younger than 45 years, those not in sinus rhythm, and those with poor quality tracings were excluded. The electrocardiographic data were divided into three categories depending on the frontal P wave axis, ie, >60 degrees, 60 degrees, or <60 degrees, by each criterion (P amplitude lead III > lead I and a negative P wave in aVL).ResultsSixty-six percent of patients had a P wave axis > 60 degrees based on aVL, and 88% of patients had a P wave axis > 60 degrees based on the P wave in lead III being greater than in lead I.ConclusionA P wave in lead III greater than that in lead I is a more sensitive marker than a negative P wave in aVL for diagnosing emphysema and is recommended for rapid routine screening.

Electrocardiographic changes in Emphysema

“…As depicted in Figure 1 and Figure 2 , a vertical P vector can be primarily determined by two methods on a standard 12-lead electrocardiogram—P wave amplitude in lead III greater than in lead I (bipolar lead set) and/or a predominantly negative P wave in lead aVL (unipolar lead set)[ 2 , 13 , 14 ]. Out of these two criteria, the bipolar lead set appears to be more sensitive.…”

“…Out of these two criteria, the bipolar lead set appears to be more sensitive. A recent study from our group reviewed 100 consecutive ECGs of patients with a known diagnosis of emphysema found the bipolar lead set to be a more sensitive marker of vertical P-wave axis in emphysema than the unipolar lead set (sensitivity 88% vs 66% respectively)[ 13 ]. This study excluded patients younger than 45 years because a vertical P vector may be a normal finding in these patients[ 13 ].…”

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

“…ECGs with nonsinus and paced rhythms, and poor quality tracings were excluded, leaving 176 good-quality tracings in normal sinus rhythm. Patients <45 years of age were excluded because a vertical P-wave axis may be a normal finding in healthy children and young adults 1,3,8–10. The ECGs were then analyzed individually by three authors using a handheld 10× loop magnifier to determine the P-wave indices.…”

“…P-vectors were considered vertical (>60°) if P-wave amplitude in lead III was greater than in lead I or if net P-wave amplitude in lead aVL was negative 3,8–10. Ptf was calculated by multiplying the duration of the terminal negative phase of P-waves in V 1 (in milliseconds) and the depth of the terminal negative component of P-waves (in millimeters).…”

“…P-wave verticalization is a quasidiagnostic indicator of emphysema, and has long been described in the literature 1–10. It also bears a negative correlation with the degree of obstructive lung function and structural severity of the disease 3,6–8. Though several other ECG parameters have been well investigated in emphysema, its effects on the P-wave indices, namely P-terminal force in V 1 (Ptf), amplitude of initial positive component of P-wave in V 1 (i-PV1) and interatrial block (IAB), have not been well described by previous studies.…”