Question: process that causes the last 30 of ventricular volume to fill
[{'answer': 'Atrial systole', 'provenance': [{'wikipedia_id': '2525843', 'title': 'Cardiac cycle', 'start_paragraph_id': 10, 'start_character': 102, 'end_paragraph_id': 10, 'end_character': 116, 'bleu_score': 1.0, 'section': 'Section::::The cardiac cycle and Wiggers diagram.\n'}]}]