Extra corporeal membrane oxygenation support for neonatal vein of Galen aneurysmal malformation: Case report

Abbreviations

iNO

Inhaled nitric oxide

1 Introduction

VGAMs are congenital vascular malformations characterized by shunting of arterial flow into enlarged embryonic precursors of the vein of Galen. Transarterial embolization of neonatal VGAM is the current recommended treatment [1]. These neonates continue to have a high mortality rate despite intervention and half of those who survive have poor neurological recovery [1, 2]. The medical management of cardiac failure and pulmonary hypertension of neonatal VGAM prior to transarterial embolization can be difficult and there is limited experience of VA-ECMO support for this neonatal lesion [2, 3]. We report the use of VA-ECMO with central cannulation for treatment of high output congestive heart failure and persistent pulmonary hypertension in a neonatal VGAM that was unresponsive to medical management. VA-ECMO stabilized the patient for further endovascular intervention.

2 Case report

A 2.34 kilogram female neonate was born to a multigravida mother at 36 weeks of gestation via emergent cesarean section for fetal distress. The fetus was diagnosed to have VGAM by fetal magnetic resonance imaging (MRI) at 24 weeks of gestation. A fetal echocardiogram at the same time revealed dilated superior vena cava, mild right ventricle dilatation (RV) with normal function (RV width: 94 mm, Z score: 3.0), normal left ventricle (LV) size and function (LV width: 77 mm, Z score: 1.69), with an increased cardio-thoracic ratio of 0.53. A repeat fetal MRI at 35 weeks revealed an increase in the size of the VGAM (60×29×27 mm) and a concurrent fetal echocardiogram revealed moderately dilated right ventricle (RV width: 155 mm, Z score: 2.58) with mildly decreased function, mild to moderate tricuspid regurgitation, normal left ventricle size and function (LV width: 98 mm, Z score: –0.59) with an increased cardio-thoracic ratio of 0.68. The mother was admitted to the hospital who delivered soon thereafter. The neonate was vigorous a birth and admitted to the neonatal unit with stable vital parameters. A chest x-ray revealed cardiomegaly. An echocardiogram revealed moderate right ventricular dilatation and hypertrophy with systemic pulmonary artery pressures, dilatation of the superior vena cava and diastolic flow reversal in the descending aorta. The brain MRI measured the VGAM at 61×27×27 mm, with multiple arterial feeders at anterior and lateral margins. Her clinical assessment gave her a Bicetre score of 16 [1].

Over the next five days, the neonate gradually developed tachycardia and tachypnea requiring initiation of milrinone infusion, oxygen support and furosemide therapy. Her repeat echocardiogram on day five continued to reveal similar findings of moderately dilated right ventricle, systemic pulmonary artery pressures and preserved left ventricle function (ejection fraction: 66%) and her head ultrasound findings also remained unchanged. On day six, she developed oxygen desaturation prompting endotracheal intubation and mechanical ventilation. An echocardiogram then, revealed decreased right ventricular function with paradoxical septal wall motion, systemic pulmonary artery pressures, with preserved left ventricle function (ejection fraction: 75%). On day seven, dopamine infusion was added for hypotension and her mechanical ventilation was escalated to high frequency oscillatory ventilation for respiratory acidosis. She underwent transarterial embolization using ethylene vinyl alcohol copolymer (Onyx) of the arterial pedicles arising from right posterior cerebral artery (PCA). Residual feeders from the left PCA could not be intervened due to contrast volume restriction. She stabilized for 24 hours and a head ultrasound study revealed reduction of her VGAM size. On day eight, she again demonstrated signs of decompensation requiring initiation of inhaled nitric oxide (iNO) and additional inotropic support of epinephrine, and vasopressin. Her hypoxemia continued to worsen (oxygenation index of 34) and her arterial blood gas revealed respiratory and metabolic acidosis (pH: 7.26, PaCO₂: 66 mm Hg, PaO₂: 47 mm Hg, and serum lactate: 5.1 mmol/L). Multidisciplinary discussions were held among the Neonatology, Neurosurgery, Cardiology, Cardiac Surgery, Critical Care and ECMO services. A decision was taken to place her on VA-ECMO to stabilize her medical condition.

A median sternotomy was performed with placement of an 8 French ECMO cannula in the ascending aorta and a 10 French ECMO cannula in right atrium. VA-ECMO was able to be initiated at a high flow rate of 180 ml/kg/min with an inlet pressure of –20 mm Hg that resulted in inotropic support reduction and improvement in oxygenation. On day nine, she underwent a second transarterial Onyx and coil embolization of the left PCA arterial feeder and additional right PCA feeder via femoral arterial access. It resulted in a significant reduction of her ECMO flows to 100 ml/kg/min. A follow-up head ultrasound study revealed further decrease in the VGAM size, and presence of small bilateral parasagittal hyperechoic fluid collections concerning for subdural hematoma. Continuous electroencephalography results revealed non-clinical seizures arising from bilateral frontal regions. Over the next three days, her serial head ultrasound studies revealed similar size of subdural hematomas, there was a reduction in her seizure burden with phenobarbital, levetiracetam and midazolam and neurologically, she was opening eyes and moving all four extremities. She remained hemodynamically stable on minimal ventilator support and she was decannulated from ECMO support on day 13. Over the next five days, she however, developed multi-organ failure as evidenced by oligo-anuric renal failure, hyperbilirubinemia, decreasing levels of consciousness and rising serum lactate levels. Her condition did not improve with furosemide infusion and peritoneal dialysis. Multiple discussions were held amongst the multi-disciplinary team and the family. It was deemed that in the presence of multi-organ failure and bilateral subdural hematomas, re-initiation of ECMO support and any further neurosurgical intervention would be futile. Medical care was withdrawn, and the patient died soon thereafter.

3 Discussion

Our case report demonstrates that the medical management of neonatal VGAMs can be challenging prior to staged endovascular embolization. There may be a role for treatment of their high output cardiac failure and persistent pulmonary hypertension with VA-ECMO using central cannulation to stabilize them and safely perform transarterial embolization of VGAM.

Medical stabilization of the symptomatic neonate with VGAM can be difficult in the presence of high output cardiac failure [2]. Infants with coexisting pulmonary hypertension present an even more difficult task. No clinical trials have been performed for this rare entity and their medical treatment includes clinical assessment using Bicetre score, beta agonists, diuretics, prostaglandins, and phosphodiesterase inhibitors [1, 2]. Partial occlusion of the VGAM via staged transarterial embolization is the only treatment that has shown to reduce cardiac failure [1]. The neonate however, needs to be stabilized for transportation to the neurointerventional suite and perform the transarterial embolization safely. Our patient continued to demonstrate cardiopulmonary instability despite maximal medical management that prompted VA-ECMO support. In neonates, VA-ECMO has been suggested for management of high output biventricular failure refractory to inotropic and vasodilator support [4]. Likewise, ECMO support has been recommended for term and near-term neonates with severe pulmonary hypertension or hypoxemia that is refractory to iNO therapy [5]. Optimal ECMO management of neonates in high output states include high flow rates on the ECMO circuit [4]. Survival of children on ECMO in clinical scenarios needing high flow rates is much better with central cannulation where the right atrium and ascending aorta are cannulated directly [4]. This approach allows the highest possible flow rates, which facilitates faster resolution of shock and prevents intravascular hemolysis as seen in our patient [4]. Independent risk factors for hemolysis on ECMO including very negative inlet pressures, higher pump speeds, and narrowed cannulae can be avoided by central cannulation [6]. VA- ECMO with central cannulation in neonatal VGAMs has additional benefit of sparing the femoral artery and internal jugular vein. In the healthy newborn, the cranial venous drainage is asymmetric, usually being greater on the right [7]. As much as 80%of the neonate’s left ventricular output may be delivered to the VGAM [8]. Peripheral cannulation for VA-ECMO using the right internal jugular vein can result in severe cerebral venous congestion and intracranial hemorrhage as neonatal VGAMs have high venous return via the internal jugular vein [8]. Arterial access for transarterial embolization via the femoral artery is spared too [1, 2].

There has been one previous case report of ECMO support for medical management of neonatal VGAM that utilized peripheral cannulation, but none with central cannulation [3]. Multi-organ failure and intracranial hemorrhage seen in our patient are known complications of neonatal VGAMs [1]. It is possible that the need for anticoagulation of the ECMO circuit in our patient may have perpetuated the intracranial bleed.

In summary, neonatal VGAM remains a serious condition that requires multidisciplinary coordination among different specialties for better patient management and outcome. VA-ECMO via central cannulation is an additional armament to optimize management of high output cardiac failure and persistent pulmonary hypertension to facilitate staged transarterial embolization of the VGAM.

Financial disclosure

All the authors whose names are listed above certify that they have no financial disclosure. They have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.

Human research statement

All procedures performed in this study involving human participant were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Parents gave their written informed consent to publish the case report. Cleveland Clinic IRB waivers institutional approval for production and publication of case reports.

Funding sources

None

Conflict of interest

The authors have no conflicts of interest to declare.