Discussion

Our data demonstrate the benefit of comprehensive monitoring in identifying arterial ischaemic strokes in infants undergoing operations or cardiac catheterisation procedures during their cardiac ICU stay. Thirteen of 25 stroke episodes were identified as part of our standard monitoring practice, and less than half (11/25) of the stroke episodes were identified with clinical symptoms, with 20% (5/25) of the stroke episodes associated with focal neurologic signs or clinical seizures. Six of 25 were associated with non-specific symptoms. The remaining episode was identified by serial imaging. Patients with stroke tended to have more complex cardiac lesions, more high-risk operations, and more need for ECMO support.

The use of comprehensive monitoring and imaging for stroke detection, as demonstrated in this cohort, aligns with prior studies indicating that clinical signs alone are insufficient for timely diagnosis of stroke in critically ill infants. In our cohort, 4% of stroke patients presented with clinical seizures, 16% (4/25) with focal deficits, and 64% (14/25) were clinically asymptomatic. Our use of continuos electroencephalography, head ultrasound, and head CT in the acute post-procedure phase led to the identification of ∼60% (15/25) episodes of stroke. Our findings add to the existing literature on electroencephalography in the postoperative period with multiple studies previously demonstrating the utility of electroencephalography and continuos electroencephalography to detect seizures and predict neurologic injury. ^{Reference Claessens, Noorlag and Weeke20,Reference Lin, Du and Feng30,Reference Algra, Schouten and Jansen31} Although combined head ultrasound and EEG have been demonstrated to identify intracranial injury in the neonatal ECMO population, our study is unique in examining a real-world clinical practice of comprehensive bedside monitoring with continuos electroencephalography, serial head ultrasound, and head CT in the cardiac ICU. ^{Reference Gannon, Kornhauser and Gross29}

The stroke rate in our study cohort (6.9%) is comparable to prior works (4–19%). ^{Reference Chen, Zimmerman and Jarvik3,Reference Mahle, Tavani and Zimmerman6,Reference Beca, Gunn and Coleman8,Reference McQuillen, Barkovich and Hamrick9} Our study is unique in detailing the performance of a comprehensive monitoring practice to identify arterial ischaemic strokes. Timely detection of stroke is critical for anticoagulation and ECMO management. Similar to previous studies, more than half of the strokes (60%, 15/25) in our patient population were diagnosed with head ultrasound. ^{Reference Rollins, Yoder and Moore26,Reference Said, Guilliams and Bembea32,Reference Lazar, Abramson, Weinstein and Stolar33} This finding highlights the value of head ultrasound in in the cardiac ICU, particularly as a trigger for advanced imaging. We do not have data on the rate of false positives head ultrasounds in our patient group or percentage of patients who underwent screening head imaging that was negative. Therefore, statistical analysis, with determination of sensitivity and specificity, was not possible.

Long-term follow-up revealed persistent motor deficits in 60% of stroke survivors. Our finding of increased identification of deficits at long-term follow up is consistent with other works that have shown most infants with stroke do not demonstrate symptoms until later. ^{Reference Armstrong-Wells and Ferriero34} Multiple studies examining electroencephalography have demonstrated that abnormal activity in the post-operative period has associations with worse neurodevelopmental outcomes. ^{Reference Hanalioglu, Temkit and Hildebrandt28,Reference Latal, Wohlrab and Brotschi35–Reference Vaughan, Hammoud and Pande40} Seizures on continuos electroencephalography in the preoperative period have also been shown to be associated with worse developmental outcomes. ^{Reference Pittet, Marini and Ly41}