Introduction:
Cardiac magnetic resonance imaging (CMR) can reliably assess hemodynamics in children. Anesthetic agents may affect cerebral blood flow (CBF) and change the cerebral to systemic perfusion ratio.
Hypothesis:
Volatile anesthetic agents cause significant cerebral vasodilation resulting in descending aorta (DAo) flow reversal.
Methods:
Blood flow was measured in patients who underwent cine phase contract velocity mapping during CMR (1.5T, Philips Ingenia, Amsterdam, The Netherlands) with or without general anesthesia (GA) at our institution. Patients with a known cause for flow reversal in DAo (e.g. aortic insufficiency, aorto-pulmonary shunt/collaterals) or brain pathology were excluded. Flows in superior vena cava (SVC, surrogate for CBF), ascending aorta (AAo, measure of cardiac output), and DAo (measure of lower body perfusion) were analyzed. Measures of central tendency, standard deviation, correlation coefficient and Student’s t-test were calculated. Variables including anesthetic agents, body surface area (BSA), mechanical ventilator parameters and vital signs were assessed.
Results:
A total of 93 CMR scans were performed with GA (n=43, age 3 m to 15 y, BSA 0.29-2.4 m
2
) or without GA (n=50, 2 w to 21 y, BSA 0.2-2.89 m
2
). There was significant flow reversal in DAo (mean 7.62% +/- SD 7%) in GA group using volatile agents compared to non-GA patients (1.16% +/- 1.78%; p-value <0.001). SVC flow was higher in GA (1.66+/-1.02 ml/min/m
2
) than non-GA patients (1.28+/-0.53 ml/min/m
2
) but did not reach statistical significance (p=0.06). GA group had significantly higher SVC (cerebral blood) to AAo flow (cardiac output) ratio (0.53 +/- 0.13) than non-GA group (0.44 +/- 0.17; p=0.003), probably from increased CBF from cerebral vasodilation by volatile anesthetic agents. Patients with BSA >1.2 m
2
and GA (0.84 +/- 0.27) had a tendency to have higher SVC/DAo flow ratio compared to non-GA (0.69 +/- 0.3; p = 0.06) patients. There was a positive correlation between the end tidal CO
2
and SVC flow (r 0.486, R
2
0.236).
Conclusions:
The flow rates of SVC, AAo and DAo using CMR must be interpreted with caution in children, taking into account the effects of GA on the cerebral and lower body perfusion. This difference may be relevant in patients with congenital heart disease, especially with cavo-pulmonary and Fontan circulation.
Effects of the volatile anesthetic agents on sinus node function and atrioventricular conduction in dogs: A comparison with chloralose anesthesia
