Vein of Galen Malformation

Vein of Galen malformation (VGM) has been described in the neonatal population as a cause of congestive heart failure, hypoxic respiratory failure and pulmonary hypertension (1). VGM is a rare congenital malformation found in less than 1/25 000 newborns (2) and is associated with significant cardiovascular collapse, as well as, mortality during the early neonatal period. Interruption of VGM flow by embolization allows for reduction in output and normalization of cardiac function. Historically, neonates with cardiac failure were untreated based on the associated cerebral infarction and poor neurodevelopmental outcome (3, 4). If left untreated, VGM in the neonatal period is associated with up to 91% of mortality (5). Recent literature has found that by addressing the excess flow by neuro-intervention and by aggressive management of the cardiac failure, neonatal patients could survive without neurological impairment (6). As such, early recognition and appropriate neonatal management in a multi-disciplinary fashion allows for favorable outcome in this at-risk population (7).

Pulmonary hypertension:

Newborns with VGM can present with suprasystemic pulmonary hypertension and right and/or left ventricular dysfunction (8). Pulmonary hypertension is multi-factorial and can be the major clinical manifestation during the neonatal period. The presence of increased fetal pulmonary blood flow may lead to vascular remodeling, increasing risk for post-natal pulmonary arterial vasoconstriction (1). Indeed, cases with VGM were found on autopsy to have arteriolar medial thickening, with some vessels reduced to a “slit” like appearance on microscopy, indicating an in-utero process (1, 9). However, this is likely to represent a spectrum of disease as the rapid drop in pulmonary pressure following embolization of the VGM in some patients indicates a varying severity of the underlying fetal pulmonary vascular disease (8). Metabolic acidosis due to end-organ hypoperfusion, as well as, hypoxemia due to right to left shunting at the atrial and ductal level, can exacerbate pulmonary vasoconstriction. Furthermore, upon the loss of the low resistance utero-placental unit (6), high output towards the VGM will cause increase venous return to the right ventricle and, eventually, hyper-vascularization of the pulmonary vasculature. The above-mentioned disturbances lead to an abnormal post-natal transition and prevents the expected drop in pulmonary vascular resistance following birth. The large left to right shunt across the VGM leads to marked increase in pulmonary vascular flow and to pulmonary vascular congestion with or without reflex vasoconstriction.

Altogether, patients with VGM can present with a picture of pulmonary arterial vasoconstriction, pulmonary edema/hemorrhage due to over-circulation, or a combination of both leading to a heterogeneous pulmonary disease, further worsening the ventilation-perfusion mismatch. Furthermore, in the context of biventricular dysfunction, left ventricular end-diastolic pressure increase can lead to left atrial hypertension and pulmonary venous congestion. Management of pulmonary hypertension in this population is quite challenging. Treatment of pulmonary hypertension should focus on supporting the cardiac function and the coronary/cerebral perfusion in the context of diastolic run-off. In light of the right to left shunting at atrial and ductal level, response to oxygen supplementation will be limited. As such, oxygen toxicity should be avoided and oxygen should be titrated until no response in pre-ductal systemic saturation is found (10). Inhaled nitric oxide (iNO) may help address the component of pulmonary vasoconstriction but should be used with great caution, as it may exacerbate pulmonary vascular congestion and lead to pulmonary edema/hemorrhage. Also, in the context of left ventricular dysfunction, iNO should be avoided since the right to left ductal flow may participate in systemic output. As such, prostaglandin may be considered in patients with right ventricular failure, to unload the RV, or in the context of LV failure, to participate in providing improved systemic output. Milrinone, a phosphodiesterase 3 inhibitor, may promote ventricular relaxation (lusitrope) and decrease pulmonary arterial vasoconstriction. However, it is to be used with caution in the context of hypotension or acute kidney injury, as it is renally excreted. Finally, use of veno-arterial extracorporeal membrane oxygenation has been reported in the management of intractable pulmonary hypertension and secondary cardiac failure in a case of neonatal VGM with good outcome at follow-up (11).

Retrograde flow in the aorta secondary to the steal effect from the VOG malformation. Here seen in suprasternal arch view, as well as in subcostal view of the descending abdominal aorta. 

Signs of supra-systemic pulmonary hypertension (right to left ductus arteriosus), as well as RV dilation from volume and pressure overload. 

Torrential flow coming back by the SVC in the suprasternal view of the SVC by colour. 

Presentation on Vein of Galen Malformation by Ms Emilie St-Germain and Ms Laila Wazneh, NNP at the Montreal Children's Hospital