This thesis describes the management of patients treated with mechanical circulatory support devices for short- or long-term use. Twenty-four patients suffering from postcardiotomy heart failure were treated with a minimally invasive axial flow pump. The device was effective in unloading the failing left ventricle and in maintaining an adequate systemic circulation. The principles of perioperative monitoring, and pharmacological therapy are outlined. The pump was also used as an alternative to the heart-lung machine in conjunction with coronary artery bypass surgery. Together with a short-acting β-blocker, esmolol, the heart was decompressed and heart motion was reduced, facilitating bypass surgery on the beating heart. The anesthesiological considerations using this method are described. An implantable left ventricular assist device was used as a bridge to heart transplantation in 10 patients. We were interested in assessing the possibility to establish such a treatment program at a non-transplanting center. A multidisciplinary approach was enabled thanks to the organization of our Heart Center and due the close collaboration with our transplant center at Lund University. As one of the first centers in Europe, we established a well-functioning program with good results. Nine out of 10 of the bridge patients, with treatment times varying between 53 to 873 days, survived pump treatment and were eventually transplanted. The device proved to be powerful enough to support the failing heart and enable rehabilitation of the patients. Outpatient management became simpler when using the electrical device with belt-worn batteries. The uncertain durability and the high risk of device-related complications are shortcomings that limit its potential for more permanent treatment of heart failure. A new generation of small implantable axial blood flow pumps has therefore been developed. The principles of these pumps are based on the first generation axial flow pumps evaluated in this thesis. After several years of basic research and experimental studies, the first human implants have been performed. In the thesis, the hemodynamic effects of such a novel axial flow pump have been evaluated in an acute heart failure model. This technology holds great promise, both as a bridge to heart transplantation, and as a permanent circulatory support system. / On the day of the public defence the status of the article IV was: Submitted for publication.