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Myocardial Ischemia in a Preterm Born Baby
We report on an extremely preterm infant born at 23+4 weeks of gestation with a birthweight of 560 grams; Apgar scores were 5/8/9. The neonate was initially intubated and given surfactant for severe respiratory distress syndrome; also, an umbilical venous catheter (UVC) was inserted on day 1 of life. On day 5 of life, the infant was extubated and was started on non-invasive ventilatory support.
On day 8 of life, sudden onset of paleness was noted in this neonate as well as bradycardia and oxygen desaturation<30%. Also, bloody gastric secretions and blanching of the left little toe were noticed. However, the initial diagnostic work-up did not yield any relevant pathologic results.
Several hours later, another episode of acute clinical deterioration was observed with acute onset of atrioventricular block as well as ST-segment elevation using bedside monitoring. Electrocardiography ([Fig. 1a]) as well as laboratory tests showed typical alterations of myocardial infarction (Troponin T 2750 pg/ml, CK/CK-MB 14%). Bedside echocardiography ([Fig. 1b]) demonstrated accumulation of air in the inferior and septal segments of the left ventricle, but no air bubbles were detected on cranial and abdominal ultrasonography. On echocardiography, migration of the UVC into the left atrium with subsequent air embolism was suspected as the reason for the clinical deterioration. This finding was confirmed by conventional x-ray ([Fig. 2]). After correction of the UVC position, the clinical symptoms and pathologic findings resolved fully with no clinical sequelae.
The correct placement of UVCs should be controlled regularly (e. g. every two days) during longer dwell-times because initially correctly placed UVCs may migrate over time as seen in our patient. Most often displacement of the UVC occurs because of inadequate fixation. However, migration of UVCs into the left atrium is also possible and can be caused by a flattened diaphragm during respiratory support using positive airway pressure, or secondary to retraction of the drying umbilical cord.
Ultrasonography as well as x-ray studies or the combination of both imaging tools are appropriate and feasible for the (initial) assessment of correct UVC-placement in extremely premature infants. Moreover, meticulous control of intravenous infusions for inadvertent air entry is important, since small amounts of air might cause substantial damage in these small patients. Last but not least, the indication for leaving the UVC in situ has to be reconsidered on a daily basis.
Article published online:
03 February 2022
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