Abstract
A variety of compact ventricular assist pumps have been used to provide ventricular support since the first successful report of this technique by DeBakey and his associates. Our group has designed an air powered sac type ventricular assist pump (VAP) which has a smooth polyurethane surface and Björk-Shiley type inlet and outlet valves. This VAP has undergone extensive testing in calves and has been available for clinical use during the last five years. Of the 1, 500 adults undergoing open heart operations, 60 required intra-aortic balloon support and 19 required the VAP. When properly employed, the circulatory support provided permitted immediate separation of the patient from bypass. Definite hemodynamic evidence of improved ventricular function has been observed during the period of unloading of the deranged ventricle by the VAP. However, during the first three years of our experience, the VAP was used in 11 patients with one survivor. The initial low survival rate resulted from improper indications for use, excessive delay in applying the VAP, and problems attendant with learning a new technique. During the past two years, specific attention has been directed to use of right, left or biventricular assistance as indicated, to prompt application of the VAP when required, and use of atrial rather than ventricular cannulation for VAP inflow. Accordingly, the survival rate over this two year period has increased to 50% (four of eight patients). The short-term assist pump is an important adjuvant for the surgeon who operates on seriously ill cardiac patients. Furthermore, effective use of the short-term assist pump will provide the basis for the use of permanent forms of mechanical circulatory support.
