In distant heart procurement, optimal storage conditions remain to be defined, especially with respect to the electrolytic concentrations of storage solutions. Between December 1986 and April 1987, heart transplants were carried out in t8 patients. After cardioplegic arrest (St. Thomas), the hearts were randomly stored in either Euro-Collins' solution (ECS; n = 9) or Ringer's solution (RS; n = 9) at 4~ For the first 24 h postsurgery, atrial pressures (LAP, RAP), systemic (MAP) and pulmonary pressures (PAP), and cardiac output (CO) were monitored. In addition, catecholamine and nitroglycerine requirements as well as the type of cardiac rhythm were documented. There was no significant difference between the groups in terms of the period of graft ischemia (ECS, t62_+28 rain; RS, 141 _+47 rain); the MAP, RAP, LAP, and CO were also similar in both groups. The total amount of epinephrine needed to maintain the MAP between 60 and 80mmHg was 10.5mg/24h_+4.1mg in ECS compared with 19.9 m g / 2 4 h + 1 2 m g in RS (P<0.05). Despite less inotropic support, the left cardiac work index was considerably higher in the ECS group (P < 0.05). In the first few postoperative hours, 8/9 RS patients needed either atrial (n =4) or ventricular pacing (n =4) for a heart rate of 90-100beats/min (bpm), whereas only three ECS patients required atrial pacing ( P < 0.05). All other ECS hearts showed a spontaneous sinus rhythm. At the 24th postoperative h eight RS patients remained pacemaker-dependent, as opposed to two ECS patients with atrial and one with ventricular pacing. We conclude that storage of the donor heart in a medium with intracellular ionic composition, such as ECS, is superior to RS (extracellular composition). ECS appears to result in better preservation of cardiac performance and electrical stability of the transplanted heart.