Continuous ambulatory monitoring of absolute right ventricular pressure and mixed venous oxygen saturation in patients with heart failure using an implantable haemodynamic monitor - Results of a 1 year multicentre feasibility study

Background Implantable sensors that monitor haemodynamics over time may be useful in patients with heart failure. This multicentre study assessed the feasibility of a system that has one sensor measuring absolute pressure and another measuring mixed venous oxygen saturation (SvO(2)). Both sensors we re mounted on leads that were implanted in the right ventricle. Methods Twenty-one patients with heart failure (NYHA II-III) were included. Comparisons were made to right heart catheterizations at implant and at 2, 6 and 12 months thereafter, Patients underwent several haemodynamic provoc ations during the catheterizations. Results Overall, among functioning sensors, the IHM-1 values were highly co rrelated with reference values for all time points during all provocations, demonstrating high reproducibility and stability (r(2)=0.91, 0.79 and 0.78 for systolic, right ventricular diastolic and SvO(2) respectively). Althou gh IHM-1 underestimated reference pressure values by 4.5 mmHg and SvO(2) by 1.6%, this difference was consistent across provocation and stable over 12 months of follow-up. Twelve of the 21 oxygen sensors failed to function an d two pressure sensors had component failures. Preliminary analysis of long -term data revealed haemodynamic patterns that may be key indicators for th erapeutic interventions. Conclusion This multicentre feasibility study demonstrated the accuracy and stability of sensors implanted in the right ventricle. The IHM-1, using ri ght ventricular pressures and SvO(2) with improved performance, might be us eful in the study of pathophysiological mechanisms and treatment interventi ons in heart failure. (C) 2001 The European Society of Cardiology.