Intracranial Pressure and Cerebral Hemodynamics in Infants Before and After Glenn Procedure

Abstract

Objectives: This prospective cohort study aimed to investigate changes in intracranial pressure (ICP) and cerebral hemodynamics in infants with congenital heart disease undergoing the Glenn procedure, focusing on the relationship between superior vena cava pressure and estimated ICP.

Design: A single-center prospective cohort study.

Setting: The study was conducted in a cardiac center over 4 years (2019-2022).

Patients: Twenty-seven infants with congenital heart disease scheduled for the Glenn procedure were included in the study, and detailed patient demographics and primary diagnoses were recorded.

Interventions: Transcranial Doppler (TCD) ultrasound examinations were performed at three time points: baseline (preoperatively), postoperative while ventilated (within 24-48 hr), and at discharge. TCD parameters, blood pressure, and pulmonary artery pressure were measured.

Measurements and main results: TCD parameters included systolic flow velocity, diastolic flow velocity (dFV), mean flow velocity (mFV), pulsatility index (PI), and resistance index. Estimated ICP and cerebral perfusion pressure (CPP) were calculated using established formulas. There was a significant postoperative increase in estimated ICP from 11 mm Hg (interquartile range [IQR], 10-16 mm Hg) to 15 mm Hg (IQR, 12-21 mm Hg) postoperatively (p = 0.002) with a trend toward higher CPP from 22 mm Hg (IQR, 14-30 mm Hg) to 28 mm Hg (IQR, 22-38 mm Hg) postoperatively (p = 0.1). TCD indices reflected alterations in cerebral hemodynamics, including decreased dFV and mFV and increased PI. Intracranial hemodynamics while on positive airway pressure and after extubation were similar.

Conclusions: Glenn procedure substantially increases estimated ICP while showing a trend toward higher CPP. These findings underscore the intricate interaction between venous pressure and cerebral hemodynamics in infants undergoing the Glenn procedure. They also highlight the remarkable complexity of cerebrovascular autoregulation in maintaining stable brain perfusion under these circumstances.

Keywords: Glenn procedure; cerebral blood flow; congenital heart defects; intracranial pressure; superior vena cava; transcranial Doppler sonography.

Figure 1.

Transcranial Doppler (TCD) images of the middle cerebral artery (the red flow) in two patients after the Glenn procedure. A, Normal diastolic flow and pulsatility index (PI). B, Decreased diastolic flow and increased PI. This flow pattern of TCD indicates an elevation in intracranial pressure and reduced perfusion, mainly when the end-diastolic velocity (EDV) falls below 20 cm/s and the PI exceeds 1.4 (9). PSV = peak systolic velocity, RI = resistance index, S/D = systolic/diastolic velocity ratio, TAP = time-averaged pulsatility (or time-averaged mean velocity).

Figure 2.

Compares findings at three time points: preoperatively (baseline), postoperatively while ventilated (Glenn), and before discharge (discharge). Each boxplot represents the median (the middle line), the 25th quartile (the lower edge of the box), and the 75th quartile (the upper edge of the box). Lines extending out of the box represent the range. CPP = cerebral perfusion pressure, ICP = intracranial pressure, PI = pulsatility index.