BACKGROUND: Pulmonary 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 (\u3e60 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.
METHODS: Unselected 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, \u3e60 degrees, 60 degrees, ordegrees, by each criterion (P amplitude lead III \u3e lead I and a negative P wave in aVL).
RESULTS: Sixty-six percent of patients had a P wave axis \u3e 60 degrees based on aVL, and 88% of patients had a P wave axis \u3e 60 degrees based on the P wave in lead III being greater than in lead I.
CONCLUSION: A 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

Bajaj, Rishi

Basheer, Zainab

Chhabra, Lovely

Spodick, David H.

English

eScholarship@UMMS

University of Massachusetts Medical School eScholarship@UMMS University of Massachusetts Medical School Faculty Publications 2013-01-18 Optimal electrocardiographic limb lead set for rapid emphysema screening Rishi Bajaj Saint Vincent Hospital Et al. Let us know how access to this document benefits you. Follow this and additional works at: https://escholarship.umassmed.edu/faculty_pubs  Part of the Cardiology Commons, Diagnosis Commons, and the Respiratory Tract Diseases Commons Repository Citation Bajaj R, Chhabra L, Basheer Z, Spodick DH. (2013). Optimal electrocardiographic limb lead set for rapid emphysema screening. University of Massachusetts Medical School Faculty Publications. https://doi.org/10.2147/COPD.S37776. Retrieved from https://escholarship.umassmed.edu/faculty_pubs/218 This material is brought to you by eScholarship@UMMS. It has been accepted for inclusion in University of Massachusetts Medical School Faculty Publications by an authorized administrator of eScholarship@UMMS. For more information, please contact Lisa.Palmer@umassmed.edu. © 2013 Bajaj et al, publisher and licensee Dove Medical Press Ltd. This is an Open Access article  which permits unrestricted noncommercial use, provided the original work is properly cited.International Journal of COPD 2013:8 41–44International Journal of COPDOptimal electrocardiographic limb lead set  for rapid emphysema screeningRishi Bajaj1Lovely Chhabra1Zainab Basheer2David H Spodick31Department of Internal Medicine, University of Massachusetts Medical School, Worcester, MA, USA; 2Department of Medicine, Al Ameen Medical College, Karnataka, India; 3Department of Cardiovascular Medicine, Saint Vincent Hospital, University of Massachusetts Medical School, Worcester, MA, USACorrespondence: Lovely Chhabra 285 Plantation Street, Number 813, Worcester, MA 01604, USA Tel +1 508 667 5052 Fax +1 888 598 6647 Email lovids@hotmail.comBackground: Pulmonary emphysema of any etiology has been shown to be strongly and quasidi-agnostically 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.Methods: Unselected 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 electro-cardiographic 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).Results: Sixty-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.Conclusion: A 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.Keywords: electrocardiography, P wave axis, emphysemaIntroductionEmphysema of any etiology is nearly always caused by chronic obstructive pulmonary disease, and has been shown to be strongly and quasidiagnostically associated with a vertical frontal P wave axis.1–11 In previous investigations, we have determined that a vertical P wave axis (.60 degrees) during sinus rhythm can be used as a lone criterion to screen for pulmonary hyperinflation/emphysema, with sensitivity and specificity both being above 90%.4,5,8 Previous studies have also suggested that the degree of P vector verticalization has an inverse correlation with qualitative lung function8,9 and quantification of radiographic emphysema.12,13 A vertical P vector on a surface 12-lead electrocardiogram can be determined by two methods using limb leads, ie, a P wave amplitude in lead III greater than in lead I or a negative P wave in aVL,1,5,8 although both these electrocardiographic findings suggest a vertical P vector and theoretically both should be simultaneously present in all the patients with a vertical P vector.However, preliminary observations from our previous investigations had sug-gested that this is not the case in the clinical setting. Thus, the purpose of our current Dovepresssubmit your manuscript | www.dovepress.comDovepress 41O R I g I N A L  R E S E A R C Hopen access to scientific and medical researchOpen Access Full Text Articlehttp:dx.doi.org/10.2147/COPD.S37776International Journal of COPD 2013:8 investigation was to determine which set of limb leads would be better for identifying the vertical P vector of emphysema in adults, given that this has not been investigated previously. A P wave amplitude in lead III greater than in lead I indi-cates a P axis . 60 degrees, a P wave amplitude in lead III equal to that in lead I indicates a P axis of 60 degrees, and a P wave amplitude in lead III smaller than in lead I indicates a P axis , 60 degrees. A negative P wave in aVL indicates a P axis . 60 degrees, while a flat or equiphasic P wave in aVL indicates a P axis of 60 degrees and a positive P wave in aVL indicates a P axis , 60 degrees.1,2,5,8 Our plan was to conduct this investigation in patients having a known diagnosis of emphysema with a working hypothesis, that the set more often showing P wave verticalization would be a more sensitive (better) marker for diagnosis of emphysema. Thus, we aimed to investigate whether a P wave amplitude in lead III greater than that in lead I is a better marker of emphysema than an inverted P wave in aVL.Materials and methodsWe recorded 12-lead electrocardiograms at rest using a standard technique in unselected consecutive patients with a known diagnosis of emphysema and scheduled for a routine follow-up visit in the pulmonary clinic at our institution between March and April 2012, with the aim of obtaining a total of 100 patient electrocardiograms after application of the exclusion criteria. Inclusion criteria were age . 45 years,5–9 normal sinus rhythm, a prior confirmed diagnosis of emphy-sema with a documented clinical history, chest radiographs, and pulmonary function tests. We excluded patients aged younger than 45 years, those not in normal sinus rhythm, and those with poor quality tracings. Patients younger than 45 years of age were excluded because a vertical P wave axis may be a normal finding in healthy children and young adults.1,5,8 Paced rhythms were also excluded. The electrocardiograms were then analyzed individually by all the authors using a handheld loop magnifier to determine the frontal P wave axis/frontal P vector by accounting for the P wave amplitudes in leads I, III, and aVL. Any differences in individual observations were resolved by consensus in a conference. All patients enrolled in the investigation had a documented diagnosis of pulmonary emphysema sup-ported by clinical history, chest radiographs (findings of increased radiolucency of the lungs, a flat diaphragm, and a long, narrow heart shadow), and pulmonary function tests. Pulmonary function tests showed an obstructive airway pat-tern (forced expiratory volume in one second/forced vital capacity ratio [FEV1/FVC] ,0.70 and a forced expiratory volume in one second [FEV1] ,80% of predicted) without significant bronchodilator reversibility. Electrocardiographic data for the 100 patients were divided into three categories depending on the frontal P wave axis, ie, .60 degrees, 60 degrees, or ,60 degrees, by each criterion (ie, accounting for the P amplitude in leads III and I and the P wave in aVL). A  correlation between the frontal P axis and FEV1 was also tested for using Pearson’s correlation test.ResultsThe baseline demographic characteristics of the study popula-tion are shown in Table 1. The mean (±standard deviation) age of the patients was 68.2 ± 9.9 years, of whom 41% were male. Ninety-four percent of the patients had an active or remote smoking history, with an average of 48.3 ± 28.5 pack-years of smoking. The mean P vector was 68.6 ± 11.4 degrees and did bear an inverse correlation with FEV1 (r = −0.52; P , 0.001). Of 73 study patients who had also undergone a conventional computed tomographic scan of the chest, 66 (90.4%) had evidence of emphysematous changes. Table 2 shows the P wave axis based on P wave amplitude in leads I and III. Eighty-eight of the 100 patients had a P wave in lead III greater than the P wave in lead I, eight had a P wave in lead I equal to that in lead III, and four had a P wave greater in lead I than in lead III. Table 3 shows the P wave axis based on P wave morphology in aVL. Sixty-six of Table 1 Baseline characteristics of the study populationVariable Emphysema  patients (n = 100)P valueAge (in years) 68.2 ± 9.86 –Males (%) 41% –Frontal P axis (in degrees) 68.6 ± 11.4 –Smoking history (%) 94% –Smoking pack-years 48.3 ± 28.5 –FEV1 (%) 49.1 ± 17.8 –r (FEV1 and frontal P axis) −0.52 ,0.001Verticalization of P axis By leads I and III (bipolar limb lead set) 88 (88%) – By lead aVL (unipolar limb lead) 66 (66%) –Notes: Data are represented as n, n (%), and mean ± standard deviation; r represents correlation coefficient between FEV1 and P axis. Abbreviation: FEV1, forced expiratory volume in one second.Table 2 P axis based on P wave morphology in leads I and IIIP axis (n = 100) Emphysema (n).60 degrees (P wave in lead III . I) 88 (88%)60 degrees (P wave in lead III = I) 8 (8%),60 degrees (P wave in lead III , I) 4 (4%)Note: Data are represented as n and n (%).submit your manuscript | www.dovepress.comDovepress Dovepress42Bajaj et alInternational Journal of COPD 2013:8Table 3 P axis based on P wave morphology in lead aVLP axis (n = 100) Emphysema (n).60 degree (negative P wave in aVL) 66 (66%)60 degree (equiphasic P wave in aVL) 22 (22%),60 degree (positive P wave in aVL) 12 (12%)Note: Data are represented as n and n (%).the 100 patients had a predominantly negative P wave, 22 had a flat P wave, and 12 had a positive P wave in aVL. Sixty-two patients had a P axis . 60 degrees by both criteria. An electrocardiographic tracing showing P wave amplitude in lead III greater than in lead I and an unequivocally negative P wave in aVL during sinus rhythm is shown in Figure 1. The study results demonstrated that a P wave amplitude in lead III greater than in lead I (sensitivity 88%) is a more sensitive marker of emphysema than an inverted P wave in aVL (sensitivity 66%).DiscussionFrontal P wave verticalization has been shown to have a close correlation with emphysema and has been extensively studied in previous investigations.1–8 Moreover, increasing verticality of the frontal P vector correlates with increas-ing degrees of airway obstruction,8,9 degree of depression of the diaphragm,3 and radiographic quantification of the disease.12,13 A possible mechanism of P wave axis verti-calization in lung hyperinflation is that the right atrium is firmly attached to the diaphragm by a dense pericardial ligament around the inferior vena cava.3 With progressive flattening of the diaphragm, the right atrium is distorted/dis-placed inferiorly, causing a significant rightward deviation (verticalization) of the P wave axis. A prospective blinded investigation of patients with purely (fibrotic) restrictive, compared with purely obstructive pulmonary disease showed the P axis to follow the level of the diaphragm, such that patients with restrictive lung disease and high dia-phragms had horizontal and leftward P axes, while patients with low diaphragms and obstructive lung disease had verti-cal P axes.3 In the study by Baljepally et al,5 the sensitivity and specificity of a P axis . 60 degrees for emphysema was found to be 89% and 96%, respectively. In another study by Chhabra et al,8 sensitivity and specificity of a vertical P axis for diagnosing emphysema was 94.7% and 86.4%, respectively. From prior correlation studies,5,8 it is clear that a vertical P axis on an electrocardiogram is the single most common screening tool, which is highly sensitive and specific in diagnosing emphysema at a glance.5,8 Both studies5,8 used electrocardiographic criteria (a P amplitude in lead III greater than in lead I and/or a dominantly  negative P wave in aVL) to determine P wave verticalization. In the present study, we took this further by investigating the percentage of patients with emphysema who have a domi-nantly negative or inverted P wave in aVL compared with a P wave in lead III greater than that in lead I; 88% of the emphysema patients had a P wave in lead III greater than that in lead I, and only 66% of the patients had an inverted or negative P wave in aVL. In an ideal theoretical setting, the P wave amplitude should be negative in aVL when the P wave amplitude in lead III is greater than in lead I (suggesting a vertical P vector), but this was not found in a practical clinical setting, which could be possibly due to a commonly encountered variable/high skin resistance or poor surface contact at aVL producing a spurious “augmented” extremity (unipolar) lead abnormality.14 Thus, the results suggest that the bipolar lead set is more sensitive for rapid characterization of emphysema than the unipolar set.Figure 1 Electrocardiographic tracing representing a vertical P vector: P wave amplitude in lead III greater than P wave in lead I and an unequivocally negative P wave in aVL during sinus rhythm.submit your manuscript | www.dovepress.comDovepress Dovepress43Emphysema screening with optimal limb lead setInternational Journal of COPDPublish your work in this journalSubmit your manuscript here: http://www.dovepress.com/international-journal-of-copd-journalThe International Journal of COPD is an international, peer-reviewed journal of therapeutics and pharmacology focusing on concise rapid reporting of clinical studies and reviews in COPD. Special focus is given to the pathophysiological processes underlying the disease, intervention programs, patient focused education, and self management protocols. This journal is indexed on PubMed Central, MedLine and CAS. The manuscript management system is completely online and includes a very quick and fair peer-review system, which is all easy to use. Visit http://www.dovepress.com/testimonials.php to read real quotes from published authors.International Journal of COPD 2013:8LimitationsAll patients enrolled had a known diagnosis of emphysema (based on chest radiographs and pulmonary function tests), so the specificity of both these electrocardiographic criteria for diagnosing emphysema could not be estimated in the current study. Emphysema was diagnosed based on clinical history, chest radiographs, and pulmonary function tests. High resolution computed tomographic scanning was not used to confirm the diagnosis, and is known to have a higher sensitivity and specificity for diagnosing structural emphy-sematous changes.ConclusionElectrocardiographic analysis of 100 patients with clinically documented emphysema prompted the following  conclusions. The vertical P axis (.60 degrees) on an electrocardiogram is a unique characteristic of obstructive pulmonary disease in adults and is the single most important tool for identifying emphysema by electrocardiogram, and serves as a virtual screening test at a glance. A P wave in lead III larger than in lead I is a more sensitive marker for rapid identification of emphysema compared with an inverted P wave in aVL.DisclosureThe authors report no conflicts of interest in this work.References1. Spodick DH. Electrocardiographic studies in pulmonary disease. I. Electrocardiographic abnormalities in diffuse lung disease. Circulation. 1959;20:1067–1072. 2. Zuckerman R, Cabrera CE, Fishleder BL, Sodi-Pallares D. The electro-cardiogram in chronic cor pulmonale. Am Heart J. 1948;35:421–425. 3. Shah NS, Koller SM, Janower ML, Spodick DH. Diaphragm levels as determinants of P axis in restrictive vs obstructive pulmonary disease. Chest. 1995;107:697–700. 4. Thomas AJ, Apiyasawat S, Spodick DH. Electrocardiographic detection of emphysema. Am J Cardiol. 2011;107:1090–1092. 5. Baljepally R, Spodick DH. Electrocardiographic screening for emphysema: the frontal plane P axis. Clin Cardiol. 1999;22:226–228. 6. Littmann D. The electrocardiographic f indings in pulmonary  emphysema. Am J Cardiol. 1960;5:339–348. 7. Spodick DH. Electrocardiographic studies in pulmonary disease. II. Establishment of criteria for the electrocardiographic inference of dif-fuse lung diseases. Circulation. 1959;20:1073–1074. 8. Chhabra L, Sareen P, Perli D, Srinivasan I, Spodick DH. Vertical P-wave axis: the electrocardiographic synonym for pulmonary emphysema and its severity. Indian Heart J. 2012;64:40–42. 9. Spodick DH. Vectorcardiogram in pulmonary emphysema: its relation to scalar electrocardiographic findings. Am Rev Respir Dis. 1968;98: 634–639. 10. Chhabra L, Spodick DH. Transient Super-Himalayan P-waves in severe pulmonary emphysema. J Electrocardiol. 2012;45:26–27. 11. Zambrano SS, Moussave MS, Spodick DH. QRS duration in chronic obstructive lung disease. J Electrocardiol. 1974;7:35–36. 12. Chhabra L, Sareen P, Gandagule A, Spodick DH. Visual computed tomographic scoring of emphysema and its correlation with its diag-nostic electrocardiographic sign: the frontal P vector. J Electrocardiol. 2012;45:136–140. 13. Chhabra L, Sareen P, Gandagule A, Spodick D. Computerized tomo-graphic quantification of chronic obstructive pulmonary disease as the principal determinant of frontal P vector. Am J Cardiol. 2012;109: 1046–1049. 14. Schwarzschild MM, Hoffman I, Kissin M. Errors in unipolar limb leads caused by unbalanced skin resistances, and a device for their  elimination. Am Heart J. 1954;48:235–248.submit your manuscript | www.dovepress.comDovepress DovepressDovepress44Bajaj et al

Optimal electrocardiographic limb lead set for rapid emphysema screening

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Optimal electrocardiographic limb lead set for rapid emphysema screening

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