[A study of the right ventricular load at the unilateral pulmonary artery occlusion test after pneumonectomy]

After pneumonectomy, it is recognized that the absolute reduction of the pulmonary vascular bed makes the right ventricular afterload increase and can cause right heart failure in patients with low cardiopulmonary reserve. Therefore, we investigated how the right ventricular load was predicted by UPAO test, comparing hemodynamics at the time of the test with those after pneumonectomy in patients with lung cancer. At the test, the absolute reduction of the pulmonary vascular bed made the right ventricular afterload increase but the right ventricular pump function was maintained at the preoperative level by the increase of the right ventricular work load, namely, by the contraction of the right ventricle. After pneumonectomy, the absolute reduction of the vascular bed did not always make the afterload increase and in spite of the decreased preload the pump function was maintained at the preoperative level by increased heart rate. Additionally, the increase of the right ventricular work load improved during early postoperative days. It was concluded that UPAO test was apt to overestimate the right ventricular load of the postoperative day because it was done under the condition of the different compensatory function from the postoperative hypovolemic change.