The field of robotic-assisted laparoscopic surgery increases all the time. Older and more fragile patients which are not suitable for major open surgery could be scheduled for robotic- assisted surgery. The peroperative anesthesiological challenges and stresses during this type of surgery could anyway be even more prominent. The extreme positioning of patients during robotic surgery in the pelvis, often 30 degrees head down tilting (Trendelenburg positioning), should increase the work load of the heart significantly. There are no studies concerning fragile patients with heart failure during these conditions. In this study the circulatory effects in patients with normal heart function and preexisting heart failure will be studied during robotic surgery in extreme Trendelenburg positioning During surgery the work load and performance of the heart will be monitored using an esophageal doppler and optical spectrophotometry measuring regional saturation of the brain. This study can identify patients at risk of developing critical circulatory failure during this type of surgery.