Fall in aortic diastolic pressure immediately after aortic valve destruction can predict severity of regurgitation through the valve and chronic morphological changes in the left ventricle

Aortic regurgitation (AR) has been studied experimentally, however these reports did not investigate compensatory mechanisms in AR in relation with the severity of regurgitation. If the severity of AR can be changed voluntarily, we can evaluate the pathophysiological response to AR in wide range. The purposes of this study were 1) to see if the extent of fall in aortic diastolic pressure immediately after the production of AR (delta AoDP) was a reliable predictor of the severity of AR and 2) to evaluate the process of adaptation through acute and chronic stage in moderate AR in the rabbit model. AR was produced by perforating the aortic valves in Japanese white rabbits. First, aortic pressure, volume, weight and wall thickness of the left ventricle were measured. Correlations between delta AoDP and body weight-corrected volume (LVV/BW) and weight (LVW/BW) were studied in 18 rabbits soon after, 19 one week after, 23 four weeks after and 10 eight weeks after the production of AR. delta AoDP was closely correlated with LVV/BW after 1 week (1 week: R = 0.667, p less than 0.01, 4 weeks: R = 0.733, p less than 0.01, 8 weeks: R = 0.757, p less than 0.05) and with LVW/BW after 4 weeks (4 weeks: R = 0.484, p less than 0.05, 8 weeks: R = 0.651, p less than 0.05). The slope of these regression equations increased with time (delta AoDP and LVV/BW: 1 week: 0.0138, 4 weeks: 0.0361, 8 weeks: 0.0577 ml/kg.mmHg; delta AoDP and LVW/BW; 4 weeks: 0.0142 8 weeks: 0.0310 g/kg.mmHg).(ABSTRACT TRUNCATED AT 250 WORDS)