Vasoplegia is a common complication after heart surgery for heart failure. With vasoplegia, the blood vessels can no longer squeeze properly, causing low blood pressure that is sometimes difficult to treat with medication. One of the causes of this complication is likely to be the use of the heart-lung machine, a device that takes over the function of the heart and lungs during surgery. The blood then comes into contact with a foreign environment and this can cause a reaction of the immune system. Patients with heart failure are extra sensitive to this reaction. CytoSorb device is a filter that can be built into the heart-lung machine and can reduce the response of the immune system. Therefore, this study aims to investigate whether the use of this filter during heart surgery in patients with heart failure results in a less frequent occurrence of vasoplegia after surgery.