Non-invasive cardiac output monitoring (NICOM) in adult congenital heart disease patients with Fontan palliation

Rationale Fontan palliation for single ventricle malformations is an increasingly common reason for heart failure in the adult population. Cardiac output (CO) measurement in Fontan physiology is achieved by invasive cardiac catheterization (RHC). Noninvasive CO monitors using thoracic bioreactance (NICOM) have been validated in non-congenital patients but have not been studied in adult Fontan patients. Objective To compare RHC obtained values of CO using the Fick equation with those measured simultaneously by NICOM in a cohort of adults with Fontan palliation. Methods and results In nineteen patients undergoing routine outpatient RHC, we compared CO values as determined by Fick with those generated by the Starling SV NICOM device. Bland-Altman plots and intraclass correlation coefficients (ICCs) revealed internal consistency within NICOM measurements, however the agreement between RHC and NICOM for CO was poor (ICCs ​∼ ​0.40). We performed sub-analyses using two-sample T-tests and ICCs to determine if clinical cyanosis, acute desaturation, or Fontan pressure affected the difference observed between RHC and NICOM. Neither chronic hypoxia, acute desaturation, nor Fontan pressure measures were found to be associated with the observed difference between the RHC and NICOM measured CO. Discussion and conclusion Our study did not find a correlation between RHC and NICOM derived measures of CO in a cohort of Fontan patients, even in sub-analyses of confounders of Fontan physiology. We observed internal consistency within the device, which may open a role for monitoring of trends rather than absolute values in Fontan patients. Our study was limited due to small sample size.