UltraTrac for Cardiac Output Monitoring in Congenital Heart Disease (UltraTrac)

Participants undergoing clinically indicated cardiac catheterization will have UltraTrac measurements obtained and compared with thermodilution and/or direct Fick cardiac output measurements obtained as part of standard clinical care.

UltraTrac is an investigational wearable hemodynamic monitoring device that integrates impedance cardiography and carotid Doppler ultrasound into a single noninvasive platform. In this study, UltraTrac will be used only as an observational monitoring device. UltraTrac measurements will not guide clinical decision-making, and all clinical management will proceed according to standard of care.

• UltraTrac Wearable Hemodynamic Monitoring Device

Participants undergoing clinically indicated cardiac MRI will have UltraTrac measurements obtained near the time of cardiac MRI and compared with CMR-derived cardiac output measurements obtained as part of standard clinical care.

UltraTrac is an investigational wearable hemodynamic monitoring device that integrates impedance cardiography and carotid Doppler ultrasound into a single noninvasive platform. In this study, UltraTrac will be used only as an observational monitoring device. UltraTrac measurements will not guide clinical decision-making, and all clinical management will proceed according to standard of care.

• UltraTrac Wearable Hemodynamic Monitoring Device

Participants admitted to the cardiac intensive care unit will have UltraTrac measurements obtained before and after clinically indicated introduction or titration of vasoactive medications. UltraTrac trending will be compared with concurrent clinical hemodynamic assessments.

UltraTrac is an investigational wearable hemodynamic monitoring device that integrates impedance cardiography and carotid Doppler ultrasound into a single noninvasive platform. In this study, UltraTrac will be used only as an observational monitoring device. UltraTrac measurements will not guide clinical decision-making, and all clinical management will proceed according to standard of care.

• UltraTrac Wearable Hemodynamic Monitoring Device

Agreement between cardiac output measurements obtained periprocedural by UltraTrac and cardiac output measurements obtained by thermodilution and/or direct Fick method during clinically indicated cardiac catheterization will be assessed using Bland-Altman analysis. Percentage error will be calculated as two standard deviations of the bias divided by the mean cardiac output of the two methods. A percentage error of 30% or less will be considered clinically acceptable agreement.

Periprocedural agreement between UltraTrac-derived and CMR-derived cardiac output (L/min) and cardiac index (L/min/m²) will be assessed using Bland-Altman analysis. CMR-derived cardiac output will be obtained during clinically indicated cardiac MRI using phase contrast flow measurement and volumetric assessment. Each participant will contribute one measurement pair per encounter, consisting of one CMR-derived cardiac output value and the temporally closest UltraTrac-derived measurement. Reported parameters will include mean bias, limits of agreement, percentage error, and 95% confidence intervals for the bias and limits of agreement. Percentage error will be calculated as 2 standard deviations of the bias divided by the mean cardiac output of the two methods × 100. Percentage error ≤30% will indicate clinically acceptable agreement by Critchley and Critchley criteria. Results will be reported overall and by age group, weight category, and cardiac anatomy.

The ability of UltraTrac to detect directional changes in cardiac output will be assessed during the immediate postoperative period and throughout the broader CICU admission. Measurements will be obtained during pre-defined windows before and after each clinically indicated vasoactive medication initiation or titration event. The composite clinical reference standard will include heart rate, arterial blood pressure, capillary refill time, acid-base status and lactate, and invasive hemodynamic parameters where available (arterial line, central venous pressure). Concordance between UltraTrac-derived directional cardiac output changes and composite clinical hemodynamic assessment will be reported as a concordance rate (%). The specific statistical method for concordance analysis will be determined and pre-specified prior to data collection and will be detailed in the statistical analysis plan.

Feasibility of UltraTrac device placement and signal acquisition will be assessed as the proportion of enrolled participants with successful device placement and analyzable waveform data acquisition across the cardiac catheterization laboratory, cardiac MRI suite, and cardiac intensive care unit settings.

Time required for UltraTrac device application will be recorded by study personnel during the specific clinical setting in which the device is applied.

Comfort and tolerability of device application will be assessed using the UltraTrac Tolerability and Comfort Questionnaire, a standardized instrument developed and defined prospectively by the study team prior to data collection. The questionnaire uses a 5-point rating scale ranging from 1 (minimum, very uncomfortable or intolerable) to 5 (maximum, completely comfortable and well tolerated), where higher scores indicate a better outcome. The questionnaire will be administered to the participant, caregiver, or both at the time of device removal following each study encounter. Mean scores and standard deviations will be reported for the overall cohort and stratified by age group, clinical setting, and device application duration.

Signal quality will be assessed using the UltraTrac Waveform Signal Quality Scale, a standardized 5-point rating scale ranging from 1 (minimum, uninterpretable waveform) to 5 (maximum, optimal waveform quality), where higher scores indicate a better outcome. This scale was developed and defined prospectively by the study team prior to data collection. Scores will be assigned independently to ICG and carotid Doppler waveform acquisitions by two blinded reviewers. Mean scores and standard deviations will be reported for the overall cohort and across the following pre-specified subgroups: age (neonates 0-30 days, infants 31 days-12 months, children 1-12 years, adolescents and young adults 13-21 years, and adults 22 years and older), weight (<3 kg, 3-10 kg, 10-20 kg, >20 kg), and cardiac anatomy (single ventricle vs. biventricular). Inter-rater agreement will be reported using intraclass correlation coefficient.