Vectorcardiographic Study of Obstructive Pulmonary Disease Part 1. Effect of Expiratory and Inspiratory Breath-holding on Vectorcardiogram in Chronic Obstructive Pulmonary Dise ase

Abstract

An altered lung volume and electrical resistance of the tissues surrounding the heart can affect vectorcardiographic changes. This study was designed to evaluate whether the altered lung volume by expiratory and inspiratory breath-holding can produce any change of vectorcardiogram. Patients with chronic obstructive pulmonary disease (COPD), but without respiratory failure, were divided into 3 groups according to forced expiratory volume in one second (FEY 1.0 % ): Group 1, consisted of 15 cases with FEV1.0% of 71% or more; Group 2,19 cases of 55% to 70%; Group 3,24 cases of 55% or less. Vectorcardiographic changes, anatomical axis of the heart, diaphragmatic movement determined by chest X-P and gas analysis by exercise testing were investigated in 58 COPD patients and 15 normal men.
1) There was max QRS vector showing backward rotation by deep inspiration in Group 1, Group 3 and normal men. The downward movement changes of max QRS vector by dee p inspiration were seen in Group 1, Group 2 and normal men.
2) The magnitude of max QRS vector by deep inspiration was reduced significantly in Group 2 and normal men and correlated with a decrement of lung triangle area. (Lung triangle area is an area of left side chest X-P; this triangle is formed by three points of bifurcatio trachea, posterior phrenicocostal sinus and a point of intersection of diaphragram and posterior margin of the heart.)
3) The max QRS vector of frontal plane in Group 3 showed greater downward deviation by deep expiration than normal men. The max QRS vector of horizontal plane showed greate r backward deviation by deep expiration than normal men. The magnitude of max QRS vector by deep expiration in Grpup 3 showed significant lower value than normal men. This can be explained adequately on the basis of irreversible inflated lung in patients w ith COPD.
4) Anatomical axis was closely related to electrical axis in normal men in deep expiratory and inspiratory breath-holding, but there was no significant relation in patients with COPD.
5) A decrement of max QRS vector magnitude in frontal plane correlated with a decrement of lung triangle area in Group 2.
6) A good relation was found between movement of diaphragm and FEV1.0%, between an area change of lung triangle and FEV1.0%.
7) PO₂ showed a more significant decrease after Master's 2 steps exercise in patients with poor diaphragramatic movement than in patients with good diaphragmatic movemen t. There was no significant difference in positive rate of Master's 2 steps exercise among the groups. Group 3 showed lower value of PO₂and higher value of PCO2 than normal me n, induced by exercise.
In the light of the evidence, it would seem most probable that the experimental data presented for these supine subjects can most simply be explained on the assumption that the vectorcardiographic changes in COPD, in which max QRS vector become oriented more to the right posterior and inferor direction, are the direct result of excessive lung volume around the heart at the extreme of breath-holding