Case description

A term female newborn with a birth weight of approximately 2.3 kg was transferred during the first days after birth because of persistent tachypnea, intermittent oxygen requirement, cardiomegaly, and a prominent continuous murmur. The early postnatal course had initially appeared relatively reassuring after brief respiratory support, but feeding was suboptimal and the infant subsequently developed progressive cardiorespiratory instability. On arrival, the infant had an active precordium and a harsh murmur audible across the chest. A palpable pulsation and audible bruit over the anterior fontanelle raised immediate concern for a cerebral arteriovenous malformation. Urgent MRI and vascular imaging confirmed a giant choroidal-type VOGM supplied by multiple arterial feeders arising from both the anterior and posterior cerebral circulations. The malformation drained into a markedly enlarged median prosencephalic venous collector, with dilation of the vein of Galen, transverse and sigmoid sinuses, and internal jugular veins. There was associated mass effect on the midbrain and cerebellar vermis, mild ventriculomegaly, and supratentorial white-matter volume loss. Multifocal white-matter signal abnormalities were interpreted as chronic prenatal injury with superimposed subacute changes, likely related to the combined effects of vascular steal, impaired cerebral perfusion, venous hypertension, and hypoxic injury.

Over the following hours, the infant required intubation and developed oliguria, metabolic acidosis, and a rising lactate concentration. Targeted Neonatal Echocardiography revealed striking high-flow physiology: severe enlargement of the superior vena cava (SVC), right atrium (RA), right ventricle (RV), main pulmonary artery (MPA), and pulmonary valve annulus; turbulent high-velocity venous inflow through the SVC and right heart; and retrograde flow in the aortic arch directed toward the head and neck vessels.

Step by Step TNE findings

At the time of the comprehensive TNE, invasive blood pressure was approximately 70/30 mmHg. The study demonstrated a structurally normal four-chamber heart with concordant atrioventricular and ventriculoarterial connections and no obstructive aortic arch lesion. The dominant abnormality was an extreme high-flow circulation caused by the low-resistance intracranial arteriovenous shunt. The SVC was markedly dilated and demonstrated exceptionally robust colour flow. Pulsed-wave Doppler showed a large velocity–time integral, reflecting the enormous volume of blood returning from the cerebral arteriovenous circuit. In VOGM, this is one of the most recognizable echocardiographic clues. The finding should not be interpreted as simply “good SVC flow”: it represents recirculation through the malformation and does not measure effective systemic and cerebral oxygen delivery.

Right-heart volume and pressure loading

The RA and RV were dilated, with RV hypertrophy. The MPA and pulmonary valve annulus were also enlarged, consistent with chronically increased prenatal and postnatal flow through the right ventricular outflow tract. Colour Doppler demonstrated torrential flow entering the RA and traversing the RV. This right-heart enlargement reflects the extraordinary preload returning through the SVC, while the RV simultaneously faces an elevated pulmonary arterial pressure that may have some component of reactive pulmonary vascular resistance (to tamponade the excessive flow; as well as from prenatal remodelling due to endothelial shear stress from the increased fetal pulmonary blood flow).

Pulmonary hypertension: pressure alone does not define the mechanism

Tricuspid regurgitation had a peak gradient of approximately 65-70 mmHg. When added to estimated RA pressure, the calculated RV systolic pressure exceeded the simultaneously measured systemic systolic pressure. Pulmonary artery Doppler notching and a flattened interventricular septum at peak systole supported at least systemic and likely suprasystemic, pulmonary hypertension. These findings establish high pulmonary arterial pressure, but they do not establish high pulmonary vascular resistance (PVR). Pulmonary arterial pressure is determined by pulmonary blood flow multiplied by PVR, with pulmonary capillary wedge pressure also contributing. In this infant, ventricular outputs were markedly elevated, approximately 400 mL/kg/min from each ventricle, favoring a major flow-mediated component. The phenotype could still contain a resistance-mediated component from prenatal pulmonary vascular remodeling or acute pulmonary vasoconstriction; the two mechanisms are not mutually exclusive.

Atrial-level shunting: decompression of an overwhelmed right atrium

The patent foramen ovale showed predominantly right-to-left, with intermittent bidirectional, shunting. This pattern reflected the combination of enormous SVC return, elevated RA pressure, RV loading, and pulmonary hypertension. Atrial right-to-left flow provided a route for right-heart decompression but contributed to preductal desaturation. The direction of atrial shunting should therefore be interpreted as part of the pressure and flow balance, not as an isolated marker of “PPHN.”

The ductus arteriosus: a critical systemic pathway

The PDA was predominantly right-to-left. In severe VOGM physiology, the right-to-left ductal shunt may decompress the pressure-loaded RV and contribute blood to the descending aorta. The aortic filling pressure is affected by the ongoing steal from the significant cerebral malformation; leading to decreased descending aorta filling. The lesion can therefore behave as a functionally duct-dependent systemic circulation even though the aortic arch is anatomically unobstructed (so called "pseudo-coarctation" physiology). However, not all ductal blood necessarily reaches the lower body. Because the cerebral AVM is an exceptionally low-resistance circuit, part of the blood entering the descending aorta through the PDA may be drawn retrogradely around the arch toward the head and neck vessels. The net benefit of the PDA must therefore be assessed by examining the entire arch, the direction and magnitude of aortic flow, systemic perfusion markers, and serial clinical response. The PDA had become substantially smaller while remaining predominantly right-to-left. At the same time, oliguria, lactate, and metabolic acidosis were worsening. This temporal association raised concern that progressive ductal restriction was removing an important compensatory pathway for RV decompression and postductal systemic perfusion.

The defining arterial signature: aortic flow reversal toward the brain

The aortic arch and descending aorta demonstrated marked retrograde flow, particularly during diastole, directed toward the head and neck vessels and ultimately the VOGM. This is the echocardiographic expression of systemic steal. A large fraction of total ventricular output was recirculating through the cerebral AV shunt rather than providing nutritive flow to the myocardium (via the coronaries), kidneys, bowel, liver, and lower body. Coronary perfusion may have been further impacted by low diastolic blood pressure and increased ventricular end-diastolic pressure; as well as increased coronary sinus pressure draining in the loaded right atrium) The physiology resembles coarctation because lower-body perfusion is compromised and may depend on right-to-left ductal flow, but there is no fixed anatomic obstruction. The cerebral malformation becomes the dominant low-resistance pathway (the vacuum), producing aortic underfilling and reverse flow. For this reason, the term pseudo-coarctation physiology is useful when clearly defined.

Ventricular output and function: high output is not high systemic delivery

Measured RV and LV outputs were both markedly elevated, near 400 mL/kg/min. LV ejection fraction was approximately 55%, with shortening fraction in the high 20s. RV systolic function was decreased by FAC. Nevertheless, LV performance was considered borderline relative to the extraordinary workload and changing loading conditions. This distinction is fundamental. Cardiac output describes volume ejected by the ventricle, not the proportion reaching systemic organs. A newborn can therefore have a very high calculated output and simultaneously experience systemic shock. In VOGM, much of the output returns rapidly through the low-resistance cerebral shunt, generating high SVC flow and repeated cardiac recirculation. Effective systemic flow may remain critically low. The myocardium is also exposed to a dangerous supply–demand imbalance. High heart rate, chamber work, and total output increase myocardial oxygen consumption, while diastolic aortic runoff lowers diastolic pressure and may compromise coronary perfusion. Secondary ventricular dysfunction or ischemia may therefore appear even when intrinsic myocardial contractility was initially normal.

TNE synthesis

Severe neonatal VOGM with an extreme high-flow cerebral AV circuit, predominantly flow-mediated pulmonary hypertension, right-heart volume and pressure loading, marked aortic systemic steal, and evolving functional duct-dependence for RV decompression and postductal systemic perfusion. Ventricular systolic function was broadly preserved but the LV was operating at the lower limit of adequacy for the imposed workload. The rising lactate, oliguria, and metabolic acidosis were interpreted as evidence that high total output was failing to translate into effective systemic oxygen delivery. Progressive PDA restriction was particularly concerning because systemic perfusion appeared increasingly dependent on right-to-left ductal flow.

The immediate objectives were to preserve systemic oxygen delivery, support ventricular performance, avoid interventions that would intensify the cerebral or pulmonary steal, and facilitate urgent multidisciplinary neurovascular assessment.

• Our approach was to maintain/restore ductal patency with low-dose prostaglandin E1 (0.005 mcg/kg/min), titrated to the minimum dose achieving the desired physiologic effect, given the smaller PDA, predominant right-to-left flow, worsening perfusion, and need for RV decompression.

• Our approach was to support cardiac performance with dobutamine, with close monitoring of heart rate, rhythm, lactate, blood pressure, urine output, and serial ventricular function. The objective is improved effective delivery rather than simply a higher calculated output.

• Avoid reflexive pulmonary vasodilation unless comprehensive TNE supports a clinically important resistance-mediated component. In a predominantly flow-mediated phenotype, iNO or excessive oxygen may increase pulmonary blood flow, reduce right-to-left ductal support, and worsen systemic steal or pulmonary venous congestion

  • Indeed, increasing SVR may further augment the shunt towards the VOGM. As well, decreasing PVR with pulmonary vasodilators may steal from the right to left shunting at the ductal level and further increased pulmonary blood flow. PBF seemed to be increased based on pulmonary venous return assessment and pulmonary congestion on chest radiography. Our approache was to avoid iNO and agents with profound effects on SVR (epinephrine, norepinephrine, dopamine).

• Use oxygen to achieve an individualized preductal saturation target (90-95%) rather than pursuing "normal" pre- and post-ductal saturation at any cost. Avoid hyperoxia and excessive hypocapnia that may drive pulmonary vasodilation and alter ductal shunting.

• Optimize ventilation while avoiding excessive mean airway pressure, which may impair venous return, increase RV afterload, and reduce LV preload. Sedation and reduced metabolic demand may be helpful when clinically appropriate.

• Avoid indiscriminate volume loading. The right heart is already exposed to massive preload, and additional volume may worsen congestion without improving effective systemic flow.

• Trend invasive blood pressure, particularly diastolic pressure; pre- and postductal saturations; lactate; urine output; renal and hepatic indices; acid–base status; hemoglobin; and, where available, cerebral and somatic NIRS.

• Perform serial comprehensive TNE because the balance among flow, PVR, ductal patency, ventricular function, and systemic steal can change rapidly during transition and treatment.

• Coordinate cardiology, neonatal hemodynamics, neurology, neuroradiology, neurointervention, anesthesia, and intensive care teams. Definitive control of the excessive shunt requires endovascular intervention when medical stabilization is insufficient.

Discussion: back to basics

VOGM is not a true aneurysm of the mature vein of Galen. It arises from arteriovenous fistulous connections between cerebral arteries and the persistent median prosencephalic vein of Markowski, an embryonic precursor that normally regresses. Choroidal lesions generally contain multiple arterial feeders and are more likely than mural lesions to produce severe neonatal cardiovascular disease. The malformation establishes a low-resistance intracranial circuit capable of receiving a very large proportion of combined cardiac output. During fetal life, the placenta provides another large low-resistance circuit. It competes with the cerebral shunt and partially buffers its systemic consequences. Nevertheless, increased venous return can already produce cardiomegaly, right-sided dilation, TR, high pulmonary blood flow, and pulmonary vascular remodeling. Preferential flow toward the head may reduce antegrade flow across the aortic isthmus, sometimes creating prenatal concern for arch hypoplasia or coarctation.

At birth, placental separation abruptly removes the competing low-resistance bed. Over the next hours and days, PVR falls and pulmonary blood flow rises. The VOGM then becomes an increasingly dominant low-resistance pathway. Simultaneously, the ductus begins to constrict. The convergence of falling PVR, increasing pulmonary and systemic recirculation, and decreasing ductal support explains why some newborns appear initially stable and deteriorate around the second or third day. The term “high-output failure” is commonly used but can conceal the relevant physiology. The ventricles may eject two or more times the expected output, yet the infant may have oliguria, acidosis, hepatic dysfunction, bowel hypoperfusion, and rising lactate. The problem is not necessarily an inability to generate flow. It is the distribution and effectiveness of that flow. Blood passes through the low-resistance AVM, returns through the cerebral venous system and SVC, crosses the right heart and pulmonary circulation, returns to the left heart, and is again preferentially directed toward the AVM. This recirculation produces spectacular ventricular outputs and SVC flow. Meanwhile, forward descending aortic flow may be minimal. The appropriate clinical question is therefore not “Is the cardiac output high?” but “How much effective oxygenated blood reaches the systemic organs?”

Pulmonary hypertension phenotypes

VOGM-associated PH is heterogeneous and dynamic. A high TR gradient or flattened septum identifies pressure loading but cannot reveal its cause. A physiology-based assessment should consider pulmonary blood flow, PVR, left atrial pressure, RV performance, ductal shunt, ventricular outputs, and pulmonary venous return.

Why pulmonary vasodilators may help, fail, or harm

iNO is logical when elevated PVR is a dominant and reversible driver of RV pressure and low pulmonary blood flow. It is not a treatment for pressure caused primarily by excessive flow. In flow-mediated PH, reducing PVR can further increase pulmonary blood flow and pulmonary venous return, raise left atrial pressure, and worsen pulmonary edema or hemorrhage. It may also lower pulmonary artery pressure enough to reduce the right-to-left PDA contribution on which the descending circulation depends.

Why the PDA may be lifesaving and still physiologically complex

In the most severe cases, the PDA is not an incidental transitional structure. It can serve as an RV pressure-relief pathway and a source of descending aortic flow. PGE1 may therefore be appropriate when the PDA is restricting and systemic perfusion or RV function is deteriorating. The lowest effective dose is attractive because PGE1 can also lower systemic and pulmonary vascular tone, decrease diastolic pressure, and potentially alter flow through the malformation. A large right-to-left PDA does not guarantee adequate lower-body perfusion. Some ductal blood may be recruited retrogradely toward the AVM. This is why the duct must be evaluated together with arch Doppler, diastolic pressure, lactate, urine output, and organ function.

Systemic and myocardial consequences of diastolic steal

Diastolic aortic runoff reduces perfusion pressure to systemic organs. Renal hypoperfusion contributes to oliguria and activation of the renin–angiotensin system. Mesenteric and hepatic perfusion may also be compromised. The myocardium faces high oxygen demand from extreme workload while coronary driving pressure may be impaired by low diastolic pressure. These mechanisms create susceptibility to secondary LV or RV dysfunction, myocardial ischemia, and arrhythmia.

The cerebral consequences: more than arterial steal

The cerebral injury associated with VOGM is multifactorial. Preferential arterial flow toward the malformation can reduce nutritive perfusion of the developing brain, while the massive venous return produces intracranial venous hypertension and interferes with normal cerebral venous drainage. These abnormalities may coexist with reduced systemic oxygen delivery and impaired diastolic perfusion. Consequently, brain injury may develop antenatally and may include white-matter volume loss, chronic ischemic changes, ventriculomegaly, and, in severe cases, progressive tissue injury. In this infant, the combination of chronic volume loss and more recent signal abnormalities suggested that the cerebral consequences preceded the acute postnatal cardiovascular deterioration.

TNE before, during, and after embolization

Endovascular embolization is the definitive means of reducing shunt flow. Neonatal procedures are commonly staged because abrupt elimination of the low-resistance circuit can produce a sudden increase in effective SVR and LV afterload. The physiology resembles post-ligation (or PDA catheter-closure) cardiac syndrome: systemic hypertension/hypotension, reduced LV systolic performance, elevated left atrial pressure, pulmonary venous congestion, and respiratory deterioration may follow. TNE can contribute at three stages. Before intervention, it defines phenotype and determines whether medical stabilization is improving effective systemic delivery. During intervention, serial assessment of SVC flow, aortic reversal, LV systolic and diastolic performance, and strain may help judge how much shunt reduction is tolerated. After intervention, TNE detects the rise in LV afterload, evolving dysfunction, pulmonary venous hypertension, and the need for carefully titrated afterload reduction such as milrinone in selected patients.

A practical TNE checklist for suspected neonatal VOGM

• Confirm structural anatomy and exclude congenital heart disease or true aortic arch obstruction.

• Assess SVC size, colour-flow prominence, pulsed-wave Doppler, and serial shunt burden.

• Measure RA, RV, pulmonary valve, and MPA dimensions; document RV hypertrophy and septal geometry.

• Estimate RV pressure using TR and compare with simultaneous systemic blood pressure.

• Evaluate pulmonary artery acceleration, notching, and pulmonary venous return.

• Measure RV and LV outputs while acknowledging their substantial technical limitations at extreme flow.

• Assess RV function with FAC, TAPSE, tissue Doppler, and qualitative performance; assess LV EF, shortening, diastolic indices, and strain where available.

• Document PFO and PDA direction, caliber, restriction, and temporal variability.

• Interrogate the transverse arch, aortic isthmus, descending aorta, and abdominal aorta for systolic and diastolic reversal.

• Integrate the echo with diastolic pressure, pre/postductal saturation, lactate, urine output, renal and hepatic function, perfusion examination, and NIRS.

• State the predominant phenotype and whether it appears flow-mediated, resistance-mediated, RV-dysfunction dominant, mixed, or evolving.

• Repeat the study after any major change in oxygen, ventilation, vasoactive therapy, PGE1, perfusion, or neurovascular intervention.

Teaching points

• A massively dilated SVC with unusually robust flow is a major echocardiographic clue to a cerebral high-flow AV malformation.

• High ventricular output does not equal adequate systemic perfusion. Effective flow may be critically reduced by cerebral recirculation and aortic steal.

• Pulmonary hypertension in VOGM is often substantially flow-mediated. A high TR gradient alone must never be equated with elevated PVR.

• The most severe VOGM can behave as a duct-dependent systemic circulation despite a normal aortic arch.

• Predominantly right-to-left PDA and PFO shunts are compensatory expressions of the pressure and flow burden, not merely generic signs of PPHN.

• Retrograde aortic flow toward the brain is the defining signature of systemic steal and should be documented carefully with colour and spectral Doppler.

• Falling PVR and ductal constriction explain delayed deterioration during the first postnatal days.

• iNO may worsen a flow-mediated phenotype by increasing pulmonary flow and reducing right-to-left ductal support.

• Serial TNE matters because the phenotype can change rapidly with transition, therapy, and embolization.

• The purpose of neonatal embolization is physiologic stabilization through staged shunt reduction, not necessarily immediate complete obliteration.

Targeted Neonatal Echocardiography

Cerebral MRI

Brain MRI with MRA and MRV demonstrated a giant choroidal-type vein of Galen aneurysmal malformation supplied by both the anterior and posterior circulations, with drainage into a markedly dilated median prosencephalic vein, vein of Galen, transverse and sigmoid sinuses, and internal jugular veins. No venous thrombosis was identified. The enlarged venous collector exerted mass effect on the right midbrain, superior cerebellar vermis, and cerebral aqueduct, with mild supratentorial ventriculomegaly but no transependymal CSF flow. The cerebellar vermis was complete but small, and there was supratentorial white-matter volume loss with multifocal signal abnormalities and associated brainstem thinning, consistent with chronic prenatal hypoxic–ischemic injury related to cerebral steal, with superimposed subacute injury. Overall, the findings were consistent with a giant choroidal vein of Galen malformation complicated by subacute-on-chronic hypoxic–ischemic brain injury.