Vein of Galen Malformation

Management:

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 and steal from the systemic circulation. In the context of left ventricular dysfunction, iNO should be avoided since the right to left ductal flow may participate in systemic output. Prostaglandin may be considered in patients with right ventricular failure, to unload the RV, or in the context of poor systemic flow, 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. Inotropic support can help the RV cope until embolization in cases of severe VOGM (dobutamine or epinephrine). 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). However, it is particularly challenging as ECMO does not alter the steal via the VOGM. 

Embolization is a complex procedure that requires highly specialized neuro-interventional radiology expertise in neonatal cerebrovascular interventions. At the Montreal Children's Hospital, we follow a collaborative, multidisciplinary protocol involving neuro-interventional radiology, neurosurgery, neonatology, neonatal hemodynamics, cardiology, the ECMO team, cardiac anesthesia, and neuroradiology for urgent rapid MRI within the first hours of life. This protocol is activated prenatally when the malformation is diagnosed in utero, allowing for early coordination and individualized perinatal management. While the goal is to delay embolization to later infancy when feasible, it may become urgently necessary in cases of extreme hemodynamic instability, particularly when managing large, high-flow vascular malformations that threaten cardiac function and systemic perfusion.

Protocolized approach

Prenatal and Perinatal Consultation and Coordination Plan

• Pediatric Cardiology consultation, including fetal echocardiography.

• Neonatology-Perinatal Medicine consultation for perinatal management planning. Meeting with the family and visit of the unit. 

• Genetics consultation to assess for underlying syndromic associations.

• Neurology, Neuroradiology, Fetal MRI, and Neuro-Interventional consultation for comprehensive neurovascular assessment.

• Neurosurgery consultation to be on standby on the day of the procedure if needed.

• Prenatal consultation with Cardiac Anesthesia to prepare for potential postnatal embolization and perioperative management.

• Inform the NICU team (physicians, nurses, respiratory therapists) about the case and the expected delivery date to ensure optimal preparation.

• Notify the Interventional Radiology (IR) team and Pediatric Neuroradiology about the delivery date to coordinate MRI and catheterization lab availability.

• Organize a prenatal multidisciplinary meeting within the Fetal Diagnosis and Treatment Group to establish a coordinated perinatal and postnatal management plan.

Birth Planning and Delivery Considerations for Vein of Galen Malformation (VOGM)

1. Pre-Delivery Coordination

• The delivery date should be planned in advance to ensure availability of all consulting specialists, team, equipments and technical platforms (neonatology, neurology, neurosurgery, neuro-interventional radiology, pediatric cardiology, cardiac anesthesia, ECMO team, and neuroradiology).

• Consultants should be notified as early as possible to allow adequate preparation.

2. Delivery Mode Considerations

• The decision regarding a planned C-section should be individualized, considering the size of the Vein of Galen Malformation and potential hemodynamic instability at birth.

• If an elective C-section is planned, discuss the timing and logistics with maternal-fetal medicine and obstetrics teams.

• VOGM is not a contra-indication to vaginal birth or delayed cord clamping. However, DCC should not be done if the baby is non reactive at birth. 

3. Prenatal Huddle and Rehearsal

• A prenatal multidisciplinary meeting (huddle) should be held a few days before the expected delivery date to finalize the care plan and rehearse resuscitation steps. A pre-delivery simulation with all the planned players and in the days prior to anticipated birth may be performed depending on the prenatal severity level. 

• Ensure that the team participating in the huddle will be available on the day of delivery.

4. Antenatal Steroid Considerations

• If an elective C-section is planned before 37 weeks, administration of antenatal betamethasone should be considered, unless there are maternal contraindications.

• These neonates are at high risk of respiratory complications due to:

  • Pulmonary hypoplasia secondary to right ventricular enlargement and compression of the pulmonary circulation.

  • Potential postnatal high-output cardiac failure, which may exacerbate respiratory distress.

• In these exceptional circumstances, the NICU team considers antenatal steroids to minimize the confounding effects of respiratory distress syndrome (RDS).

5. Delivery Room Preparation & Immediate Postnatal Care

• Delivery takes place in the delivery suite convertable into an operating room and nested within our NICU unit. Resuscitation nurses ensure that the O-negative blood is prepared and in the room. Epinephrine infusion is ready, as well as umbilical lines (double lumen UVL) and regular necessary material for resuscitation. 

• Essential preparations should include:

  • Electrodes pre-installed for immediate ECG monitoring.

  • Umbilical lines ready for prompt placement.

  • Pre-drawn epinephrine available in the delivery room. Resuscitation doses and infusion. 

  • Discussion of delayed cord clamping on a case-by-case basis, balancing the risks of high-output failure with the benefits of placental transfusion.

  • Clear role assignments for all team members to ensure a coordinated resuscitation approach.

Admission & Initial Stabilization

• The newborn should be admitted to a large, fully equipped NICU room with one-to-one nursing care to facilitate intensive monitoring.

• Ventilatory Support:

  • Primary ventilator: VN500

  • Consider HFOV or JET ventilation in cases of associated pulmonary hypoplasia, which may result from right ventricular enlargement and pulmonary compression.

  • Low threshold for intubation in neonates showing signs of cardiac and/or respiratory failure to optimize oxygenation, reduce metabolic demand, and facilitate hemodynamic stability.

  • Avoid excessive mean airway pressure (MAP) due to the risk of pneumothorax (i.e. risk of pulmonary hypoplasia). As well, high MAP may significantly increase intra-thoracic pressure and central venous pressure, which may worsen cerebral venous pressure and precipitate intra-ventricular hemorrhage. High MAP may also worsen RV afterload and reduce LV preload. 

Fluid & Hemodynamic Considerations

• Avoid excessive volume resuscitation unless there is concern for acute blood loss, as right ventricular dysfunction limits the ability to handle excessive preload.

• Install umbilical venous (double lumen) and arterial lines immediately for:

  • Blood gas analysis, lactate, electrolytes, glucose, calcium, CBC, liver enzymes, urea, creatinine, cross-match, baseline coagulation profile, fibrinogen. Consideration for baseline NT-proBNP.

  • Gaz, electrolytes, glucose and lactate levels should be monitored frequently until stability is ascertain. 

Early Cardiac & Neurovascular Evaluation

• NIRS installation and routine neuro-vital signs and routine vital signs. Aim pre-ductal saturation >85%.

• Head circumference q6hours.

• Echocardiography / TNE should be performed within the first 12 hours of life to assess:

  • Cardiac transition and RV function

  • Pulmonary pressures and PDA shunting dynamics

  • Evidence of right-to-left shunting at the atrial or ductal level

• Early postnatal multidisciplinary consultation with:

  • Cardiology, anesthesia, neuro-intervention, neurology, genetics, and neuroradiology.

  • Brain MRI should be discussed with the neuro-intervention and neuroradiology teams.

  • An early postnatal multidisciplinary meeting should be convened to confirm the management plan, particularly regarding the timing of neuro-intervention and hemodynamic stabilization strategies.

Hemodynamic Management: The goal is to stabilize hemodynamics before embolization, prioritizing ventilation, sedation, and fluid optimization to reduce myocardial demand.

Key Strategies:

• Inhaled Nitric Oxide (iNO):

  • Try to avoid unless there are signs of severe RV failure. It may reduce pulmonary vasoconstriction, improving pulmonary blood flow.

  • Use with caution, as it may exacerbate pulmonary vascular congestion and lead to pulmonary edema or hemorrhage due to excessive left-to-right shunting through the AVM.

  • May lead to steal effect from the systemic circulation in a pseudo-coarctation physiology. 

• Prostaglandin E1 (PGE1):

  • Consider in RV failure to keep the ductus arteriosus patent as a pressure pop-off, reducing RV afterload.

  • May also be beneficial in improving systemic output.

  • May lead to systemic vasodilation and decrease diastolic pressure. These patients often have diastolic hypotension due to the run-off by the systemic steal into the VOGM. Diastolic hypotension may worsen coronary perfusion.  

• Milrinone:

  • May promote ventricular relaxation and reduce pulmonary arterial vasoconstriction.

  • Despite low systemic afterload due to the AVM shunt, extracranial systemic vascular resistance (SVR) is often high due to reactive distal constriction in the context of the significant systemic steal in the VOGM lesion and peripheral vasoconstriction.

  • Cautious use of milrinone may improve systolic and diastolic function, enhance systemic perfusion, and induce both systemic and pulmonary vasodilation. However, it may also accumulate in the context of renal failure and cause catastrophic systemic hypotension. Further, there is controversy regarding its potential vasodilatory effect in the cerebral circulation which may worsen the VOGM shunt. 

• Dobutamine/Epinephrine

  • Supports cardiac function (inotropy); however, caution is required due to potential adverse effects: Epinephrine may exacerbate lactatemia, potentially complicating metabolic management in these critically ill neonates. Dobutamine can increase heart rate, reducing diastolic filling time, which may be detrimental in patients with preload-dependent circulation. Both medications can increase myocardial oxygen consumption, which is concerning in the presence of compromised coronary perfusion. Mechanisms of Coronary Ischemia in VOGM: Diastolic steal phenomenon: The VOGM acts as a vascular sink, diverting blood flow away from the systemic circulation during diastole—the phase when coronary arteries are perfused. Coronary venous hypertension: The coronary sinus drains into the right atrium (RA), where elevated central venous pressure (CVP) due to RA overload further impairs coronary venous return, worsening myocardial ischemia.

  • Dopamine is typically avoided as it may increase significantly the PVR. 

• Vasopressors

  • Norepinephrine, Phenylephrine or Vasopressin may improve the Systemic:Pulmonary ratio. These medications may increases systemic vascular resistance (SVR), attempting to counteract systemic steal. By raising diastolic pressure, they can help maintaining coronary perfusion without significantly increasing heart rate (except norepinephrine which may increase a bit the heart rate). These medications can supports diastolic blood pressure, improving cerebral and myocardial perfusion

  • However, they may further increase peripheral vasoconstriction at the expense of shunting more blood into the VOGM, as it will unlikely vasoconstrict the vessels within the VOGM. Theoretically, there is a risk that the SVR increase may redirect volume flow to the VOGM. Further, it may increase the cardiac afterload and worsen dysfunction when present. As such, it may be used to temporarily restore the diastolic pressure which improves the transcoronary gradient and re-establish improved coronary perfusion. Coronary circulation faces high venous pressure in the context of right atrial pressure rise (where the coronary sinus drains). 

  • Patients with VOGM are at high risk of SiADH, hyponatremia and pre-renal AKI. As such, Vasopressin should be used with great caution in these contexts as it may exacerbate hyponatremia by its ADH action on the kidneys. 

• Hydrocortisone

  • May be beneficial if there is a concern of adrenal (or relative adrenal) insufficiency, as some of these patients may have pituitary dysfunction. It may also help normalizes phosphodiesterase-5 activity in the pulmonary vasculature and enhance the response to endogenous or exogenous catecholamine.

Procedural hemodynamics

Not all VOGM require neonatal internvention. Careful multidisciplinary evaluations are necessary to outline the optimal timing for intervention. During the procedure, selective feeders to the lesion are embolized by a neuro-interventional radiology expert. Access can be achieved via umbilical vessels if cannulated since birth. The primary goal is to reduce excessive pulmonary blood flow while avoiding a sudden increase in systemic vascular resistance (SVR). Hemodynamically significant vein of Galen malformations (VOGM) often induce systemic vasoconstriction to compensate for the perceived low systemic flow caused by the vascular steal from the lesion (P ~ F x R). Post-embolization, an abrupt occlusion of too many feeders can drastically reduce VOGM flow, leading to a paradoxical increase in anterograde flow from the left ventricle (LV) in the systemic circulation. This sudden change forces the LV to face a higher SVR and increased afterload, as blood is redirected through the systemic circulation instead of the low-resistance VOGM lesion. The rapid rise in LV afterload can precipitate significant LV dysfunction. To mitigate this risk, patients often require staged, carefully planned embolization performed by an experienced team specializing in cerebral arteriovenous and vascular malformations. Further, systemic afterload reduction such as with agents with milrinone may support this transition from the significant vascular malformation peri-embolization. Post-intervention, these patients would require repeat monitoring, MRI, TnECHO and NT-proBNP to follow ventricular loading markers. A rapid increase in SVR that is not supported with afterload reduction can lead to significantly impaired LV function and output, while increasing LA pressure which can worsen pulmonary drainage (leading to respiratory failure). In cases of profoundly low blood pressure, an agent like dobutamine can be considered to support LV function, while the duct can be maintained open to promote right to left systemic perfusion by the RV. 

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