Effects of air-flow limitation on the electrocardiogram in chronic obstructive pulmonary diseases (COPD).

Electrocardiographic studies have been carried out in one hundred and thirty patients of chronic obstructive pulmonary disease (COPD). The possible influence of air-flow limitation, alveolar air trapping, hypoxaemia and hypercapnia on the electrocardiographic findings indicative of right-sided cardiac involvement have been investigated. Thus, the findings: P greater than 2.5 mm, P-axis over +90 degrees, QRS axis over +90 degrees, RV6 less than or equal to 5mm and R/S ratio in V5 V6 less than or equal to 1.0 showed a significant negative correlation with FEV1/FVC ratio. The other features like Ta waves, negative P in AVL, S greater than 5 mm in depth in V5-6 and S1,S2,S3 pattern were observed to be less frequent and correlated weakly with the severity of the disease as judged by the lung function status. The reduction of FEV1/FVC was associated with increased residual volume (air trapping), hypoxaemia and hypercapnia. It is concluded that the ECG changes indicative of right-sided cardiac involvement may be produced by a combination of increased alveolar air trapping and blood gases derangement.