Unusual electrocardiographic manifestations in conditions with increased intrathoracic pressure.

Clinical, electrocardiographic and haemodynamic findings of 10 patients suffering from intrathoracic conditions were analyzed. Three patients suffering from left spontaneous pneumothorax, three from large left pleural effusion, three from traumatic rupture of the left diaphragm and one from sliding hiatus hernia were found to have electrocardiographic alternation, while their central venous pressure and pulmonary capillary wedge pressure were increased. With the correction of the condition the electrocardiographic alternation disappeared and the pressures returned to normal. The increase in direct or indirect pressure exerted on the global surface of the heart, as it is reflected in pulmonary capillary and venous pressures, seems to be the cause of the electrical alternation observed in these patients.