Discussion

We report, for the first time in an infant, an uncommon venous systemic-to-pulmonary shunt resulting in a refractory cyanosis, due to multiple collateral vessels after an undiagnosed neonatal catheter-related venous thrombosis.

The asymptomatic character of the initial deep venous thrombosis in our patient is not uncommon, and in the general population, some studies showed that asymptomatic form could reach more than 1% of hospitalised patients.^{Reference Zubrow, Urie and Jurkovitz4}

Acquired right-to-left shunts have been reported in the adult population with various clinical presentations and underlying conditions.^{Reference Gilkeson, Nyberg and Sachs5} After neoplasia, the second most frequent cause of acquired right to left shunt is related to deep venous thrombosis, with various origins, from fibrosis mediastinitis to clotting disorders. In these cases, a triggering factor for thrombosis such as repetitive surgeries, or a venous central catheter, was often reported. Only one case was described in a child secondary to a thoracic surgery.^{Reference Saliba, El-Rassi and Smayra6}

These acquired right to left shunts are well known in the CHD population, in particular, in patients with Fontan circulation.^{Reference Gilkeson, Nyberg and Sachs5,Reference Kapur, Paik, Rezaei and Vu7} It can reach more than 50% of those patients with essential collaterals located above the diaphragm that are the result of recanalisation of embryological venous collaterals also known as bronchial venous plexuses. Recanalisation occurs as a result of increased venous pressures, well described in Fontan patients. The physiopathology is likely the same in our patient, with however a very different origin.

In neonates, the use of central catheters usually remains limited to the neonatal ICUs. The development of less invasive biomedical materials and the promotion of new vascular sites are intended to limit catheter-related complications. In the current era, peripheral inserted central catheter is the privileged access, to the detriment of femoral and subclavian central catheters.^{Reference Vidal, Sharathkumar, Glover and Faustino2} However, extremely premature infants remain at risk of catheter-related complications. Currently, there is a lack of evidence for prophylactic anticoagulation.^{Reference Vidal, Sharathkumar, Glover and Faustino2,Reference Monagle, Chan and Goldenberg8} Targeted echography screening should be considered in neonates with central venous line in the absence of acute clinical symptoms of deep venous thrombosis.

Management of catheter-related thrombosis in neonates is also a subject of controversy. Different therapeutic approaches have been considered: ‘wait and see’ strategy, standard anticoagulation, or thrombolysis. The result of the NEOCLOT study will hopefully clarify this situation.^{Reference Sol, van de Loo and Boerma9}

In opposite to the adult population, in the paediatric population, benign superior vena cava thrombosis angioplasty has been rarely reported. Two case series study reported percutaneous angioplasty procedures without any acute adverse effect, in specific and severe populations: deep venous thrombosis after heart transplantation or extracorporeal membrane oxygenation. Reinterventions were more frequent than in the adult population (30–45%).^{Reference Salavitabar, Flyer and Torres10,Reference Kazanci, McElhinney and Thiagarajan11} The level of mortality in one of the two articles (8/19 patients in Kazanci et al) was very high during the follow-up but could be explained by the severity of the disease itself, as it was as high as in the control group. Finally, in this case, the medical treatment after recanalisation included anticoagulation, as recommended, for 6 months after a venous stenting.^{Reference Ignatyev12,Reference Milinis, Thapar, Shalhoub and Davies13} Concerning the antiplatelet treatment that was prescribed afterwards, there is no consensus regarding its long-term utility, and the decision to treat was justified by the existence of a venous stent along with vascular plugs in a patient with a much abnormal systemic venous system.