Aims: The aim of this study was to evaluate the effect of the creation of a left-to-right interatrial shunt on pulmonary haemodynamics in rats with heart failure with preserved ejection fraction (HFPEF).
Methods and results: An interatrial communication (IAC) was created in 11 healthy rats (Lewis rats) and 11 rats which developed HFPEF (36-week-old spontaneously hypertensive rats [SHR]). Effects of the interatrial shunt were compared to 11 sham-operated Lewis and 11 sham-operated SHR. At 45 days post shunt, strain effect was observed in diastolic function (E/A ratio, p<0.001; isovolumetric relaxation time, p<0.001), left atrial volume (p=0.005) and pulmonary wall shear rate (WSR) (p=0.02) measured by Doppler echo. At sacrifice of the animals (60 days), a strain effect was also noted in elastin density (p=0.003) and eNOS protein expression (p=0.001). Interatrial shunt creation resulted in (i) an increase in pulmonary WSR (p=0.04) and a decrease in left atrial volume (p<0.001), (ii) an increase in elastin density (p<0.005), and (iii) an increase in eNOS protein expression (p=0.03).
Conclusions: Creation of a left-to-right atrial shunt in rats with HFPEF was effective in improving pulmonary haemodynamics. In addition, this study provides preliminary evidence of the potential risk of right volume overload and pulmonary hypertension due to atrial shunting.