Catastrophic cerebral infarction during extracorporeal life support due to a rare anomaly in the circle of Willis

Abstract

During extracorporeal life support (ECLS) in infants, cannulation of the right common carotid artery may result in a devastating ischaemic neurological injury. Herein, we present a case of an infant who encountered bilateral cerebral infarction during ECLS via the right carotid artery due to a rare and tragic anomaly of the circle of Willis. The magnetic resonance angiography complemented computed tomography in diagnosing the infarction and identifying this unique anatomy.

Extracorporeal life support, Stroke, Circle of Willis

INTRODUCTION

The incidence of cerebral infarction during extracorporeal life support (ECLS) in infants has been reported to be as high as 12.9% [1]. A recent study reported an association between carotid artery cannulation and neurological complications [2] while others indicate the opposite [3]. Carotid artery cannulation could theoretically compromise cerebral perfusion if an incomplete circle of Willis is present. In our case, such a rare anomaly led to a bilateral cerebral infarction during ECLS in an infant.

CASE REPORT

A 6-month-old male infant, 6.3 kg in body weight, previously diagnosed with tricuspid atresia and pulmonary stenosis, underwent a systemic-pulmonary shunt. Soon after admission to our hospital for elective bidirectional cavopulmonary connection, abrupt desaturation and haemodynamic collapse occurred. Cardiopulmonary resuscitation was followed by venoarterial ECLS with cannulations via the right carotid artery and the right internal jugular vein. Deep sedation and mild hypothermia were maintained for 48 h. The clinical assessment (including pupillary assessments and transcranial Doppler ultrasounds) discovered no neurological abnormalities during or after ECLS.

After 4 days, the patient was successfully weaned off ECLS with repair of the neck vessels and appeared asymptomatic. However, soon after resolution of muscle relaxation, myoclonus-like muscular contractions were noted in the face and extremities, most likely masked by relaxants. Subsequently, a computed tomography (CT) of the head detected a widespread cerebral infarction involving the right hemisphere and the left anterior cerebral artery (ACA) area (Fig. 1). The magnetic resonance angiography revealed that bilateral proximal posterior cerebral arteries (PCA-P1) were hypoplastic (foetal-type) and the proximal segment of the left ACA (ACA-A1) was aplastic. The distal part of the left ACA was supplied by the right internal carotid artery via the anterior communicating artery (Fig. 2). The patient gradually regained consciousness, albeit with persistent left hemiparesis, and underwent an uneventful bidirectional cavopulmonary connection 2 months after the ECLS episode.

Figure 1

Computed tomography status after extracorporeal life support showing cerebral infarction involving the right hemisphere and the left anterior cerebral artery area.

Figure 2

Magnetic resonance angiography showing hypoplastic bilateral proximal posterior cerebral arteries (arrows) and absence of the proximal segment of the left anterior cerebral artery (asterisk). The distal part of the left anterior cerebral artery was supplied by the right internal carotid artery via the anterior communicating artery.

DISCUSSION

Recently, carotid artery cannulation for venoarterial ECLS in paediatric patients has been associated with increased odds of neurological injury [2] and ipsilateral cerebral flow would undoubtedly be jeopardized if an incomplete circle of Willis was present during cannulation. Nevertheless, for establishing resuscitative venoarterial ECLS in small infants, the right carotid artery is the most suitable site.

Foetal-type PCA is relatively common and occasionally associated with congenital absence or hypoplasia of other cerebral arteries. The incidence of bilateral foetal-type PCA diagnosed by CT angiography has been reported to be 7.1%, with 13% of those who had unilateral or bilateral foetal-type PCA lacking ACA-A1 versus 4.1% in those who had normal PCA [4]. An anatomical study found that 3.8% of 1000 autopsy subjects had an incomplete circle of Willis [5] and the incidence of foetal-type PCA and aplastic ACA-A1 was 10.6% and 0.4%, respectively. This rare combination (hypoplastic PCA + aplastic ACA) we encountered would have benefitted from preoperative CT angiography or magnetic resonance angiography. However, due to the laborious effort required, neither of these techniques are standard diagnostic procedures in infants with ECLS. Consequently, there are no studies detailing the relationship between anatomical patterning of the circle of Willis and neurological injury in infantile ECLS. In our case, CT was an important sentinel for indicating the cerebral infarction after symptoms were observed.

In this report, we presented a case of a unique incomplete circle of Willis which caused a catastrophic brain infarction and was discovered postoperatively by CT after symptoms appeared. The magnetic resonance angiography imaging, despite difficulties in execution during the acute phase of the infarction, was able to specify the structural deficiency. These unique anomalies are hard to predict; however, if they are discovered before resuscitative ECLS, other options exist, including a trans-sternotomic approach. Although rarely encountered, unique anomalies in the circle of Willis may unexpectedly complicate ECLS and this possibility should be carefully weighed in any decision to use ECLS in infants.

Conflict of interest: none declared.