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Published on: February 11, 2017
Mesenteric blood flow response to feeding after systemic-to-pulmonary arterial shunt palliation
Yiu-fai Cheung1, Marco H K Ho, Vinson Y W Cheng
1Division of Paediatric Cardiology, Department of Paediatrics, Grantham Hospital, University of Hong Kong, Aberdeen, Hong Kong, People's Republic of China. xfcheung@hkucc.hku.hk
Insights
Infants with systemic-to-pulmonary artery shunts show reversed or absent blood flow in their superior mesenteric artery (SMA) after feeding. This suggests their splanchnic circulation adapts to protect against diastolic steal by lowering resistance.
Area of Science:
- Pediatric Cardiology
- Vascular Physiology
- Congenital Heart Disease
Background:
- Splanchnic circulation may protect against diastolic steal via systemic-to-pulmonary artery shunts by reducing resistance.
- This study investigated basal and postprandial mesenteric blood flow in infants with and without shunts.
Purpose of the Study:
- To compare splanchnic vascular resistance and blood flow velocities in infants with and without systemic-to-pulmonary artery shunts.
- To determine if splanchnic circulation adapts to protect against diastolic steal in shunted infants.
Main Methods:
- Assessed superior mesenteric arterial (SMA) time-average flow velocity (TAMV), end-diastolic flow velocity (EDFV), and relative resistance in 23 infants.
- Compared findings in 9 shunted infants (Group I) with 14 nonshunted infants (Group II) before and after feeding.
Main Results:
- Nonshunted infants (Group II) showed increased TAMV and EDFV, with decreased SMA resistance postprandially.
- Shunted infants (Group I) also had increased TAMV and decreased SMA resistance postprandially.
- Group I exhibited absent or retrograde SMA diastolic flow, unlike Group II, and had significantly lower SMA resistance overall.
Conclusions:
- Infants with systemic-to-pulmonary artery shunts experience significant splanchnic perfusion disturbances.
- Absent or reversed SMA diastolic blood flow is characteristic in these infants.
- Reduced splanchnic vascular resistance likely represents an adaptive mechanism against diastolic steal.
Background:
We hypothesized that the splanchnic circulation protects against diastolic steal through a systemic-to-pulmonary arterial shunt by reducing its resistance. To test the hypothesis we compared the basal and postprandial mesenteric blood flow velocities and vascular resistance in infants after shunt palliation for their underlying cyanotic heart disease with those in nonshunted infants.
Methods:
The basal and postprandial superior mesenteric arterial (SMA) time-average flow velocity (TAMV), end-diastolic flow velocity (EDFV), and relative resistance were assessed in 23 infants with congenital heart disease. The findings in the 9 shunted infants (group I) were compared with those in 14 nonshunted ones (group II).
Results:
In group II, TAMV (0.25 +/- 0.07 versus 0.33 +/- 0.09 m/s, p < 0.001) and EDFV (0.08 +/- 0.04 versus 0.11 +/- 0.04 m/s, p = 0.003) increased, while SMA relative resistance decreased (297 +/- 121 versus 198 +/- 73 mm Hg/ms(-1), p < 0.001) postprandially. Similarly, in group I, TAMV (0.35 +/- 0.13 versus 0.48 +/- 0.19 m/s, p = 0.008) increased, while SMA relative resistance decreased (182 +/- 61 versus 116 +/- 38 mm Hg/ms(-1), p = 0.005) after feeding. However, whereas basal and postprandial diastolic flow was antegrade in group II, absent or retrograde diastolic flow was characteristic of group I (preprandial, -0.10 +/- 0.07 m/s; postprandial, -0.13 +/- 0.06 m/s). Furthermore, group I had significantly lower SMA relative resistance both before (p = 0.02) and after (p = 0.006) feeding.
Conclusions:
Profound disturbance of splanchnic perfusion occurs in infants palliated with a systemic-to-pulmonary arterial shunt. Their basal and postprandial SMA diastolic blood flow is either absent or reversed. The lowering of basal and postprandial resistance of the splanchnic circulation probably represents an adaptive mechanism to counteract such diastolic steal.
