A total of 111 patients underwent open heart surgery during which myocardial preservation was provided by systemic hypothermia, topical cardiac cooling and cardioplegic solution (blood cardioplegia or electrolyte cardioplegia). The purpose of this study was to determine if the use of the different types of cardioplegia correlated with the occurrence of postoperative supraventricular arrhythmias and conduction disturbances. These patients were retrospectively divided into two groups according to the difference in the infused cardioplegic solutions. The group receiving blood cardioplegia (BCP) comprised 69 patients and the group receiving electrolyte cardioplegia (ECP) had 42 patients. There were a longer ischemic time and bypass time in the BCP group as compared with those of the ECP group (68.4 +/- 36.1 minutes v.s. 50.7 +/- 37.0 minutes, p less than 0.01; 93.7 +/- 48.9 minutes v.s. 65.5 +/- 39.1 minutes, p less than 0.005). However, the result shows a significantly lower incidence of supraventricular arrhythmias and conduction disturbances in the BCP group (5.8%) as compared with the ECP group (21.4%; p = 0.013). There was no significant difference in incidence of supraventricular arrhythmias and conduction disturbances between the two groups when the ischemic time was less than 60 minutes (6.7% v.s. 17.2%, p greater than 0.05). On the other hand, there was a significant difference between the two groups when the ischemic time was a significant difference between the two groups when the ischemic time was longer than 60 minutes (5.1% v.s. 30.8%, p = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)