۱- Introduction

۲- Methods

۳- Results

۴- Discussion

References

Abstract 

Background: Noninvasive cardiac output assessment is important for prognostication in patients with heart failure. Electrical velocimetry (EV), an impedance cardiography technique, can be used for noninvasive cardiac output assessment. The purpose of this study was to determine the feasibility, reproducibility and accuracy of cardiac output assessment by EV in adults with congenital heart disease (CHD). Methods: Cross-sectional study of CHD patients that had simultaneous cardiac output assessment by Fick and EV (using Cardiotronic monitor, Osypka Medical). We divided the cohort into: Group 1 patients (n = 54) had hemodynamic assessment at rest only, while Group 2 patients (n = 7) had assessment both at rest and peak exercise. Results: EV cardiac output assessment was feasible in 100% of the patients. There was good correlation between Fick-derived and EV-derived cardiac index (r = 0.89, p < 0.001) in Group 1. Among 26 patients in Group 1 that underwent cardiac output assessment pre- and post-intervention, there was no difference in the strength of correlation of Fick and EV cardiac output pre- and post-intervention (p-interaction 0.244) indicating good reproducibility of the technique. There was also modest correlation between Fick-derived and EV-derived cardiac index at rest (r = 0.68, p = 0.032), and peak exercise (r = 0.62, p = 0.055), in Group 2. Conclusion: In this study, we demonstrated the feasibility and accuracy of EV cardiac output assessment in adults with CHD. We also demonstrated, for the first time, that EV cardiac output assessment was reproducible under different loading conditions, and that EV can be used for the assessment of cardiac output augmentation at peak exercise.

Introduction

Congenital heart disease (CHD) is a common and understudied cause of heart failure [1,2]. Abnormal filling pressures and cardiac output are the hallmarks of heart failure, and are responsible for heart failure-related symptoms and morbidities [3–۶]. The assessment and longitudinal monitoring of hemodynamic indices such as cardiac output, is therefore important for prognostication and titration of therapy in patients with heart failure [7,8]. Cardiac catheterization is the gold standard for cardiac output assessment [9,10]. However, it is invasive, and hence not ideal for longitudinal monitoring. Doppler echocardiography provides noninvasive assessment of cardiac output using the continuity equation [11]. However Doppler stroke volume calculation is based on geometric assumptions about the anatomy of the left ventricular outflow tract; and these assumptions may not always be valid in CHD patients with complex anatomy [7,8]. There are very limited data about the feasibility and accuracy of Doppler-derived cardiac output assessment in the setting of complex CHD [7,8], and this may be one of the reasons why this technique is not routinely applied in clinical practice in the CHD population. Electrical velocimetry (EV) is an impedance cardiography technique that provides continuous assessment of stroke volume and cardiac output by measuring the maximum rate of change of impedance to peak aortic blood acceleration [12].