P-wave changes in chronic obstructive pulmonary disease

Electrocardiographic alterations in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality, and its incidence has grown within several years, quickly becoming the third leading cause of mortality. The disease is characterized by alveolar destruction, air-trapping, and chronic inflammation due to persistent exposure to a large spectrum of harmful particles. The diagnosis of COPD is made by demonstration of persistent and not fully reversible airflow limitation, and different phenotypes may be recognized based on pathophysiological, clinical, and radiological features. However, COPD is a systemic disease with effects involving several organs. For example, mechanical and functional alterations secondary to COPD involve heart function. Indeed, cardiovascular diseases are highly prevalent in patients affected by COPD and represent the primary cause of mortality in such patients. An electrocardiogram is a simple and cheap test that gives much information about the heart status of COPD patients. Consequently, variations from "normality" can be appreciated in these patients, with the most frequent abnormalities being P-wave, QRS axis, and ventricular repolarization abnormalities, in addition to conduction alterations and a vast number of arrhythmias. As a result, ECG should be routinely performed as a valuable tool to recognize alterations due to COPD (i.e., mechanical and functional) and possible associated heart diseases. This review aims to describe the typical ECG features in most COPD patients and to provide a systematic summary that can be used in clinical practice.

Electrocardiographic changes in Emphysema

Chronic obstructive lung disease (COPD), predominantly emphysema, causes several thoracic anatomical and hemodynamic changes which may cause changes in various electrocardiographic parameters. A 12-lead electrocardiogram (ECG), which is often a part of routine evaluation in most clinical settings, may serve as a useful screening modality for diagnosis of COPD or emphysema. Our current article aims to provide a comprehensive review of the electrocardiographic changes encountered in COPD/emphysema utilizing published PubMed and Medline literature database. Several important ECG changes are present in COPD/emphysema and may serve as a good diagnostic tool. Verticalization of P-vector, changes in QRS duration, pattern recognition of precordial R-wave progression and axial shifts can be considered some of the most valuable markers among other changes. In conclusion, 12-lead surface electrocardiogram can serve as a valuable tool for the diagnosis of COPD and/or emphysema. An appropriate knowledge of these ECG changes can not only help in the diagnosis but can also immensely help in an appropriate clinical management of these patients.

Mechanisms of ECG signs in chronic obstructive pulmonary disease

OBJECTIVE

Patients with chronic obstructive pulmonary disease (COPD) often have abnormal ECGs. Our aim was to separate the effects on ECG by airway obstruction, emphysema and right ventricular (RV) afterload in patients with COPD.

METHODS

A cross-sectional study was performed on 101 patients with COPD without left heart disease and 32 healthy age-matched controls. Body mass index (BMI) was measured, and pulmonary function tests, ECG, echocardiography and right heart catheterisation (only patients) were performed. Variables were grouped into (1) airway obstruction by FEV% (percentage of forced expiratory volume)_predicted, (2) emphysema by residual volume/total lung capacity and residual volume (percent of predicted) and (3) RV afterload by mean pulmonary pressure, artery compliance, vascular resistance and RV wall thickness.

RESULTS

In multivariate regression analysis, emphysema correlated negatively to R+S amplitudes in horizontal and frontal leads, RV/left ventricle (LV) end-diastolic volume ratio to horizontal amplitudes and BMI negatively to frontal amplitudes. Increased airway obstruction, RV afterload and BMI correlated with horizontal QRS-axis clockwise rotation. Airway obstruction, RV afterload, RV/LV end-diastolic volume ratio and BMI correlated to the Sokolow-Lyon Index for RV, and RV afterload negatively to Sokolow-LyonIndex for LV. Several classical ECG changes could, however, not be ascribed to specific mechanisms.

CONCLUSIONS

In COPD, the various pathophysiological mechanisms modify the ECG differently. Increased airway obstruction and RV afterload mainly increase the Sokolow-Lyon Index for RV mass and associate with clockwise rotation of the horizontal QRS-axis, whereas emphysema reduces the QRS amplitudes. BMI is an equally important determinant for the majority of the ECG changes.

Identification of electrocardiographic values that indicate chronic obstructive pulmonary disease

BACKGROUND

The purpose of this study was to investigate the association between respiratory function and electrocardiogram (ECG) characteristics in patients with chronic obstructive pulmonary disease (COPD), and to identify the ECG results that indicate possible COPD.

METHODS

The association between respiratory function and ECG results was retrospectively analyzed in 45 patients with COPD and 100 patients without COPD (controls).

RESULTS

Multiple logistic regression analysis revealed that QRS amplitude in lead І was a significant predictor of COPD (partial regression coefficient = -4.208, p = 0.002). Receiver operating characteristic curve analysis showed that a QRS amplitude less than 0.54 mV in lead І indicated possible COPD (sensitivity: 71%, specificity: 76%, area under the curve: 0.78 [95% confidence interval: 0.69-0.86], p < 0.001).

CONCLUSION

Low voltage in lead І (QRS less than 0.54 mV) is an important criterion in detecting COPD.

Effect of electrocardiographic P-wave axis on mortality

Although P-wave axis is routinely reported on the printouts of most contemporary electrocardiograms, the prognostic significance of its abnormality has not been systematically evaluated. We examined the association between abnormal P-wave axis and cardiovascular and all-cause mortality in 7,501 participants (53% women, mean age 59 years) from the United States Third National Health and Nutrition Examination Survey. P-wave axis of 0° to 75° was considered normal. Participants were linked to the National Death Index to identify the underlying cause of death listed on the death certificates using the International Classification of Disease. During a median follow-up of 13.8 years, a total of 2,541 deaths occurred; of which 1,077 were due to a cardiovascular cause. Abnormal P-wave axis was associated with 55% increased risk of all-cause mortality (hazard ratio [HR] 1.55, 95% confidence interval [CI] 1.43 to 1.69, p <0.01) and 41% increased risk of cardiovascular mortality (HR 1.41, 95% CI 1.24 to 1.62, p <0.01). After adjustment for age, gender, race/ethnicity, diabetes, systolic blood pressure, body mass index, smoking status, total/high-density lipoprotein cholesterol ratio, previous cardiovascular disease, chronic obstructive pulmonary disease, bronchial asthma, heart rate, and use of antiarrhythmic or atrioventricular nodal blocking drugs, the risk of mortality remained significantly high (HR 1.24 95% CI 1.13 to 1.36, p <0.01 for all-cause mortality and HR 1.19 95% CI 1.03 to 1.38, p = 0.02 for cardiovascular mortality) and was consistent across several subgroups of the participants. In conclusion, abnormal P-wave axis is associated with an increased risk of death, findings that call for attention to this routinely reported finding on contemporary electrocardiographic machines.

Computerized tomographic quantification of chronic obstructive pulmonary disease as the principal determinant of frontal P vector

Verticalization of the P-wave axis is characteristic of chronic obstructive pulmonary disease (COPD). We studied the correlation of P-wave axis and computerized tomographically quantified emphysema in patients with COPD/emphysema. Individual correlation of P-wave axis with different structural types of emphysema was also studied. High-resolution computerized tomographic scans of 23 patients >45 years old with known COPD were reviewed to assess the type and extent of emphysema using computerized tomographic densitometric parameters. Electrocardiograms were then independently reviewed and the P-wave axis was calculated in customary fashion. Degree of the P vector (DOPV) and radiographic percent emphysematous area (RPEA) were compared for statistical correlation. The P vector and RPEA were also directly compared to the forced expiratory volume at 1 second. RPEA and the P vector had a significant positive correlation in all patients (r = +0.77, p <0.0001) but correlation was very strong in patients with predominant lower lobe emphysema (r = +0.89, p <0.001). Forced expiratory volume at 1 second and the P vector had almost a linear inverse correlation in predominantly lower lobe emphysema (r = -0.92, p <0.001). DOPV positively correlated with radiographically quantified emphysema. DOPV and RPEA were strong predictors of qualitative lung function in patients with predominantly lower lobe emphysema. In conclusion, a combination of high DOPV and predominantly lower lobe emphysema indicates severe obstructive lung dysfunction in patients with COPD.

Visual computed tomographic scoring of emphysema and its correlation with its diagnostic electrocardiographic sign: the frontal P vector

BACKGROUND

Verticalization of the frontal P vector in patients older than 45 years is virtually diagnostic of pulmonary emphysema (sensitivity, 96%; specificity, 87%). We investigated the correlation of P vector and the computed tomographic visual score of emphysema (VSE) in patients with established diagnosis of chronic obstructive pulmonary disease/emphysema.

METHODS

High-resolution computed tomographic scans of 26 patients with emphysema (age, >45 years) were reviewed to assess the type and extent of emphysema using the subjective visual scoring. Electrocardiograms were independently reviewed to determine the frontal P vector. The P vector and VSE were compared for statistical correlation. Both P vector and VSE were also directly compared with the forced expiratory volume at 1 second.

RESULTS

The VSE and the orientation of the P vector (ÂP) had an overall significant positive correlation (r = +0.68; P = .0001) in all patients, but the correlation was very strong in patients with predominant lower-lobe emphysema (r = +0.88; P = .0004). Forced expiratory volume at 1 second and ÂP had almost a linear inverse correlation in predominant lower-lobe emphysema (r = -0.92; P < .0001).

CONCLUSION

Orientation of the P vector positively correlates with visually scored emphysema. Both ÂP and VSE are strong reflectors of qualitative lung function in patients with predominant lower-lobe emphysema. A combination of more vertical ÂP and predominant lower-lobe emphysema reflects severe obstructive lung dysfunction.

Vertical P-wave axis: the electrocardiographic synonym for pulmonary emphysema and its severity

BACKGROUND

The correlation between vertical P-wave axis (P-axis > 60°) and pulmonary emphysema was investigated on a very large controlled series to see if P-axis verticalisation as lone criterion can be effectively used to screen emphysema in general population. Correlation between degrees of P-axis verticalisation and the severity of the obstructive lung disease (as per global initiative for chronic obstructive lung disease [GOLD] criteria) was also studied to see if this criterion can be used for gross quantification of the chronic obstructive pulmonary disease (COPD) in routine clinical practice.

MATERIALS AND METHODS

Around 6500 unselected, routine electrocardiograms (ECGs) were reviewed which yielded 600 ECGs with vertical P-axis in sinus rhythm. 635 ECGs from the same continuum were selected with P-axis ≤60° matched for patient's age and sex serving as controls. Charts were reviewed for the diagnosis of COPD and emphysema based on medical history, pulmonary function tests, and imaging studies.

RESULTS

Prevalence of emphysema in patients with vertical P-axis was strikingly higher than in the control group: 85% vs 4.4%. The sensitivity and specificity of vertical P-axis for diagnosing emphysema was 94.76% and 86.47%, respectively. Vertical P-axis and forced expiratory volume (FEV1) were inversely correlated (Pearson correlation coefficient=-0.683). Prevalence of severe COPD was strikingly higher in patients with P-axis > 75° as compared to the group with P-axis 60°-75°: 96.3% vs 4.6%. Close to 80% of the emphysema patients with P-axis > 85° had very severe disease (FEV1 < 30%).

CONCLUSION

P-axis verticalisation is highly effective for screening emphysema and degree of verticalisation provides a gross quantification of the disease.

Electrocardiographic abnormalities in patients with severe versus mild or moderate chronic obstructive pulmonary disease followed in an academic outpatient pulmonary clinic

BACKGROUND

The prevalence of some electrocardiographic (ECG) abnormalities in severe versus mild or moderate chronic obstructive pulmonary disease (COPD) has been reported.

METHODS

ECGs were interpreted blindly in 63 patients with severe COPD (group 1) versus 83 patients with mild or moderate COPD (group 2).

RESULTS

Right atrial enlargement (RAE) occurred in 44% of group 1 and 15% of group 2 patients (P < 0.001). Right ventricular hypertrophy (RVH) occurred in 29% of group 1 and 4% of group 2 patients (P < 0.001). Right bundle branch block (RBBB) occurred in 29% of group 1 and 11% of group 2 patients (P < 0.01). Marked clockwise rotation of heart occurred in 40% of group 1 and 18% of group 2 patients (P < 0.005). Low voltage in limb leads occurred in 24% of group 1 and 11% of group 2 patients (P < 0.05). A QS pattern in leads III and aVF occurred in 16% of group 1 and 4% of group 2 patients (P < 0.01). Left axis deviation (LAD) occurred in 16% of group 1 and 4% of group 2 patients (P < 0.01). Premature atrial complexes (PACs) occurred in 19% of group 1 and 7% of group 2 patients (P < 0.05). Supraventricular tachyarrhythmias (SVTs) occurred in 16% of group 1 and 5% of group 2 patients (P < 0.025).

CONCLUSIONS

RAE, RVH, RBBB, marked clockwise rotation of heart, a QS pattern in leads III and aVF, LAD, PACs, and SVTs were significantly more prevalent in patients with severe COPD than in patients with mild or moderate COPD.

Electrocardiographic detection of emphysema

Emphysema of any pathogenesis (nearly always chronic obstructive pulmonary disease) verticalizes the frontal P-wave axis >60° in adults, which, as a single criterion, has screened for obstructive pulmonary disease. In patients with emphysema, the QRS was of a significantly shorter duration than that in matched control patients. We investigated whether combining these 2 criteria would better detect or screen for emphysema. From consecutive unselected daily electrocardiograms with sinus rhythm, 50 were selected with a P-wave axis of >60°. An equal control group from the same electrocardiogram continuum with a P-wave axis of ≤60° was matched for age and gender. The QRS durations were those measured by the electrocardiographic computer and manually verified individually. The charts were then reviewed for the diagnosis of chronic obstructive pulmonary disease and/or pulmonary emphysema according to the pulmonary function test and chest radiographic findings, respectively. The patients and controls were well matched demographically. Those with a vertical P axis had a strikingly greater incidence of emphysema than did the controls (86% vs 4%, respectively). The sensitivity of a P axis >60° was 96% and the specificity was 87%. The mean QRS duration with emphysema was significantly shorter (78 ± 8 vs 89 ± 6 ms, p <0.01). The combination of QRS duration <75 ms in conjunction with a P axis of >60° achieved a specificity of 100%, although the sensitivity decreased to 33%. We have reported multiple other cutpoints for each and for the combination. In conclusion, a P axis >60° can be used alone with very high sensitivity and specificity to detect emphysema. The verticality of the P axis is usually immediately visible in the limb leads; therefore, this could be a rapid screening test for emphysema. The specificity was increased when combined with a shortened QRS duration, at the cost of the sensitivity.

Evaluation of electrocardiographic criteria for right atrial enlargement by quantitative two-dimensional echocardiography

OBJECTIVES

This study was conducted to evaluate the sensitivity and specificity of traditional electrocardiographic (ECG) criteria for right atrial enlargement and identify improve criteria, using quantitative two-dimensional echocardiography.

BACKGROUND

Traditional ECG criteria for right atrial enlargement, such as P pulmonale, have been increasingly criticized as insensitive and nonspecific. Quantitative two-dimensional echo-cardiography has been shown to be a useful method for evaluating atrial size.

METHODS

Hospitalized patients with mild, moderate and severe right atrial enlargement were selected from our laboratory's data base and compared with age- and gender-correlated hospitalized control subjects. After exclusions, 100 patients with right atrial enlargement and 25 control patients remained. Planimetric measurement of right atrial volumes was accomplished by two independent observers using the single-plane method of discs algorithm. Electrocardiograms were independently evaluated for current and newly proposed right atrial enlargement criteria.

RESULTS

Fifty-two patients (52%) were in sinus rhythm, 41 were in atrial fibrillation, 5 were in atrial flutter, and 2 were in ectopic atrial rhythm. All control subjects were in sinus rhythm. The right atrial volume for the control group was 35.0 +/- 7.4 ml (mean +/- SD), with a narrow, roughly normal distribution. The right atrial volume for the patient group was 147.6 +/- 69.1 ml (median 127.2) in a wide, skewed distribution. The difference of mean values was highly significant (p = 0.0001). Right ventricular enlargement was found to some degree in all patients with right atrial enlargement. The most powerful predictors of right atrial enlargement were a QRS axis > 90 degrees, a P wave height in lead V2 > 1.5 mm and an R/S ratio > 1 in lead V1 in the absence of complete right bundle branch block. The combined sensitivity of these three criteria was 49%, with preservation of 100% specificity. P pulmonale detected only 6% of patients with right atrial enlargement.

CONCLUSIONS

Using quantitative two-dimensional echocardiography, we found that most previously reported ECG criteria for right atrial enlargement have low predictive power. The best predictors of right atrial enlargement were a P wave height > 1.5 mm in lead V2 and, as new criteria, a QRS axis > 90 degrees and an R/S ratio > 1 in lead V1 in the absence of complete right bundle branch block. The combined sensitivity of these three criteria was 49%, with preservation of 100% specificity. Further studies are needed to prospectively validate these findings.

Importance of recording lead V1 in the seventh right intercostal space in diagnosing corpulmonale

Right-sided chest leads V1 to V6R were recorded in the 4th to 7th intercostal spaces in 25 cases of corpulmonale secondary to chronic obstructive pulmonary disease and in an equal number of age-matched controls. Results were compared with findings in the conventional electrocardiogram. Chest leads recorded in the seventh right intercostal space along the right sternal border could detect 24% of cases of corpulmonale that were missed by conventional leads.

Lack of correlation between P pulmonale and right atrial overload in chronic obstructive airways disease

The correlation between P pulmonale and right atrial overload in chronic lung disease was studied. Right atrial pressure, pulmonary artery pressure, and cardiac output were measured with a Swan-Ganz catheter in nine patients with chronic lung disease and P pulmonale on the electrocardiogram (P wave amplitude of greater than or equal to 2.5 mm (0.25 mV) in leads II, III, and a VF. The results were compared with those in six patients with an atrial septal defect (left to right shunt greater than or equal to 50%) and six patients with pulmonary hypertension (mean pressure greater than or equal to 30 mm Hg without left sided heart disease). Right atrial volume and wall thickness were measured in 10 cases of P pulmonale among 1000 necropsy cases and compared with 141 normal hearts from the same series. The patients with P pulmonale did not show a significant increase in right atrial or pulmonary artery pressures. None of the patients with an atrial septal defect or pulmonary hypertension had P pulmonale on the electrocardiogram. In the necropsy cases of P pulmonale mean (1 SD) in right atrial volume (32 (12) ml) and wall thickness (1.5 (0.7) mm) were not significantly increased (40 (14) ml and 1.4 (0.5) mm in the normal hearts). There was a significant inverse relation between the presence of P pulmonale and the cardiothoracic ratio. In all the patients with P pulmonale chest x ray showed a low cardiothoracic ratio, a considerably depressed diaphragm, and a pendulous heart. This study showed no correlation between P pulmonale and right atrial overload in chronic lung disease. A more vertical anatomical position of the heart, particularly of the right atrium, seems to be the major factor responsible for generation of P pulmonale in chronic airways disease.

Electrocardiographic diagnosis of chamber enlargement

The purpose of this article is to review the changing role of the electrocardiogram in the diagnosis of cardiac chamber enlargement. Electrocardiographic criteria for the diagnosis of ventricular hypertrophy and atrial enlargement are reviewed in relation to autopsy, angiographic, echocardiographic and imaging findings. The electrocardiographic theory underlying the recognition of hypertropphy or dilation incorporates a number of sound physical principles that may lead to meaningful correlations with the tissue mass, chamber diameter and intracardiac blood volume. However, there are limiting factors related to the variable orientation of the heart in the chest, variable extracardiac factors and nonspecificity of each depolarization and repolarization abnormality used in the diagnosis of hypertrophy or dilation. This explains the superiority of the new noninvasive methods, in particular echocardiography, in the diagnosis of hypertrophy. Echocardiography is superior to electrocardiography in the detection of mild hypertrophy, and is more useful in the serial follow-up of changes during progression or regression of chamber enlargement.

P-wave changes in obstructive and restrictive lung diseases

To evaluate the P wave changes in the electrocardiogram (ECG) in chronic lung diseases, we examined ECGs from twenty patients with interstitial pulmonary fibrosis (the FLD group) and twenty patients with chronic obstructive lung disease (fifteen with pulmonary emphysema and five with bronchial asthma, the COLD group). In the COLD group, the amplitude of P waves in leads II and III increased and the axis of the P wave shifted rightward. In the FLD group, however, these changes were not observed. Furthermore, the axis of the P wave exceeded +70 degrees in all the patients in the COLD group, and was less than +70 degrees for all the patients in the FLD group. The increased P wave terminal force in lead V1 was found in nine patients (45%) of the FLD group and in ten patients (50%) in the COLD group. We concluded that the rightward shift of the axis of the P wave was a characteristic of obstructive lung disease and that it was mainly caused by the overinflation of the lung. This P wave change was not observed in interstitial pulmonary fibrosis.

Pseudo left axis deviation and the S1S2S3 syndrome in chronic airway obstruction

Pseudo left axis deviation (not true left axis deviation and the S1S2S3 syndrome are infrequently reported electrocardiographic findings in chronic airway obstruction. One hundred fifty-eight patients with severe chronic airway obstruction documented by pulmonary function testing were evaluated for these electrocardiographic findings. Pseudo left axis deviation was found in 23 patients (15 percent), and the S1S2S3 syndrome was found in 14 patients (9 percent). The electrocardiographic and vectorcardiographic findings are illustrated.

Electrocardiogram in chronic cor pulmonale

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