Diagnostic Values of Electrocardiogram in Chronic Obstructive Pulmonary Disease (COPD)
An EKG can show your doctor if blood flow to the heart is impaired. that connects to a machine and measures your lung capacity and air flow. Respiration rate can also be derived from the electrocardiogram. (ECG). Most airflow-sensing methods need a sensor, attached to the .. lung disease-- methodological aspects and the relationship to lung mechanics. Clin. Chronic obstructive pulmonary diseases (COPD), a broad spectrum of is a progressive disease characterized by airflow limitation/obstruction i.e. either not .. with generalised obstructive lung diseases - Its relation to ventilatory junction.
Therefore, exercise and overnight oximetry should also be performed in all patients with pulmonary hypertension. Pulmonary function tests are necessary to establish airflow obstruction or restrictive pulmonary pathology. Unless hypoxia is present, pulmonary hypertension cannot be attributed to these disorders until pulmonary function is severely reduced. Computed tomographic CT scanning of the chest with high-resolution images is useful for excluding occult interstitial lung disease and mediastinal fibrosis when the pulmonary function tests and chest radiograph are nondiagnostic.
If the cause of the pulmonary hypertension remains unexplained, chronic thromboembolism should be excluded before the diagnosis of primary pulmonary hypertension is accepted. Fortunately, ventilation-perfusion lung scanning is a reliable method for differentiating chronic thromboembolism from primary pulmonary hypertension. The finding of one or more segmental or larger perfusion defects is a sensitive marker of embolic obstruction.062 Pressure Changes during Breathing
In primary pulmonary hypertension, the ventilation-perfusion scan is normal or demonstrates patchy subsegmental abnormalities. This imaging technique has high specificity but undefined sensitivity for the diagnosis of pulmonary embolism.
Catheterization is particularly useful in diagnosing occult shunts, congenital heart disease and distal pulmonary artery stenosis. The mean heart rate in the present study was recorded as Normal sinus rhythm was recorded in Sinus tachycardia was present in Scott RC et al 12 reported arrhythmias other than sinus tachycardia to be uncommon in chronic corpulmonale.
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In the present study, peaked P-wave i. In Spodicks 13 series, Carid and Wilcken 14 found incidence of P-pulmonale in In the present series, in COPD patients, None of the cases in the present series showed low QRS amplitude in frontal and left precordial leads. The QRS axis was within normal range in T-wave inversion in leads V1 to V3 was found in only 7. Pinto et al 17 found T-wave inversion in The ECG findings were found to be Based on the findings of the study, Positive predictive value was found to be Similarly, negative predictive value was Bayesian approach for predicting probability of COPD among cases having abnormal ECG findings can also be attempted for updating clinical decisions in view of prior clinical experiences regarding patients with respiratory problems.
Measurement of mean axis direction ECGs recorded from the surface of the chest are influenced by motion of the electrodes with respect to the heart, and by changes in the electrical impedance of the thoracic cavity. The expansion and contraction of the chest which accompanies respiration results in motion of chest electrodes. Short-term changes in thoracic impedance reflect the filling and emptying of the lungs, a phenomenon which is the basis of impedance plethysmography.
These physical influences of respiration result in amplitude variations in the observed ECG figure 1. In terms of the equivalent dipole model of cardiac electrical activity, respiration induces an apparent modulation in the direction of the mean cardiac electrical axis.
- Diagnostic Values of Electrocardiogram in Chronic Obstructive Pulmonary Disease (COPD)
- Diagnosis and Treatment of Pulmonary Hypertension
- Why does your heart rate decrease when you take a deep breath?
Respiration-induced modulation of QRS amplitude. We expected that fluctuations in axis direction measurements would reflect the physical influences of respiration on the ECG, and began a study to determine if these measurements could be used to derive information about respiration.
ECG-derived respiratory signals This relationship was confirmed by comparing axis direction measurements with simultaneously recorded measurements of chest circumference using a mercury strain gauge; later studies used pneumatic respiration transducer PRT measurements.
Pulmonary Function Testing
Axis direction measurements based on chest electrodes correlate better with chest circumference and impedance than with abdomen measurements, or with direct measurements. Although many techniques for measuring the direction of the axis work well, we found that shown in figure 2 both accurate and computationally simple. After subtracting the baseline, the area of each normal QRS complex in each of two leads is measured over a fixed window the width of which is determined during the learning phase of the ECG analysis program to match the interval from the PQ junction to the J-point of a normal QRS.
Area measurements such as these are made routinely by many arrhythmia detectors, either for direct use in feature-extraction approaches, or for normalization in template-matching methods. Since the window width is fixed, the area is proportional to the mean amplitude of the signal, hence to the projection of the mean cardiac electrical vector on the lead axis.
Assuming that the leads are orthogonal, the arctangent of the ratio of the areas measured in the two leads gives the angle of the mean axis with respect to one of the lead axes. If the leads are not orthogonal, a systematic but harmless error in axis direction estimation results from this computationally convenient assumption. Estimation of the direction of the mean cardiac electrical axis from measurements of QRS area. Given that the heart rate is almost always greater than twice the respiration rate, the frequency of respiratory effort can be measured well from this limited set of samples.
Interpolation using cubic splines produces a continuous EDR signal figure 3 which bears a remarkable resemblance to the signal obtained from a PRT chest measurement.
Derivation of Respiratory Signals from Multi-lead ECGs
QRS area in V1. Cubic spline interpolation has been used between measured points in the center and upper traces. If small numbers of ectopic beats are present, they may be disregarded.
When many similar ectopic beats occur, a better strategy is to make lead axis measurements for each morphology. Measurements for beats of different morphologies will generally differ by constant angles which can be determined from the differences of the means of the measurements for each morphology.
Once these constant correction angles are known, measurements can be merged figure 4. If ectopic beat morphologies are poorly differentiated for example, if many fusion PVCs are presentthe distributions of ectopic beat measurements will not match that for normal beats, and such measurements should be discarded rather than allowing them to corrupt the EDR.
A constant correction angle is applied to the measurements obtained from the PVCs before merging them with data from normal beats.
Additional samples of the EDR can be obtained by measuring the mean axis direction during the T-wave, which in general is not parallel to that observed during the QRS complex. T-wave axis measurements may be merged into a stream of QRS axis measurements by adding a correction angle as described above. Calculation of the correction angle should be made continuously in order to track ischemic changes, which can rotate the T-wave axis relative to the QRS axis.
If only one ECG lead is available, QRS area measurements from that lead can still be used in many cases as an approximation to the respiratory signal, The single-lead EDR works best if the lead axis is significantly different from the mean electrical axis, in order to obtain a relatively large signal. Since noise does not vary in proportion to the signal, the greatest signal-to-noise ratio is usually obtained when the lead axis is orthogonal to the mean electrical axis.
EDR signals may be analyzed to determine the frequency of respiratory effort by counting peaks which follow significant level changes.