Mesenteric blood flow response to feeding after systemic-to-pulmonary arterial shunt palliation.
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.
Cheung
Yiu-fai
YF
Division of Paediatric Cardiology, Department of Paediatrics, Grantham Hospital, University of Hong Kong, Aberdeen, Hong Kong, People's Republic of China. xfcheung@hkucc.hku.hk
Ho
Marco H K
MH
Cheng
Vinson Y W
VY
D001783:Blood Flow Velocity / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D015150:Echocardiography, Doppler; D004750:Enteral Nutrition; D005260:Female; D006330:Heart Defects, Congenital / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D017538:Mesenteric Artery, Superior / Q000503:physiopathology; D010166:Palliative Care; D019518:Postprandial Period / Q000502:physiology; D011651:Pulmonary Artery / Q000601:surgery*; D013152:Splanchnic Circulation / Q000502:physiology*; D018615:Ultrasonography, Doppler, Color; D014655:Vascular Resistance / Q000502:physiology