passages.id: split_6_test_339_passage
passages.type: progene_text
passages.text: According to pilot experiments which considered various durations of global no - flow ischemia ranging from 10 to 20 minutes , two durations were chosen for the present study : 20 minutes ( group 20 ) in which ventricular fibrillation ( VF ) was the predominant form of arrhythmias , and 18 minutes ( group 18 ) in which the prevalence of VF was markedly lower despite the small difference in the duration of ischemia .