Utility of an implantable Inferior Vena Cava Sensor to quantify diuretic response in heart failure
P Kalra, M R Mehra, G Khabeishvili, M Fudim, F Malek, I Gogorishvili, C Critoph, N Uriel, K Bhatt, A Gray, J Testani, K DammanAbstract
Background
There is currently no real-time ambulatory physiological marker to quantify diuretic response. Changes in loop diuretic therapy is mostly based on nonspecific markers such as body weight and symptoms. The inferior vena cava (IVC) reflects central venous congestion and responds dynamically to changes in intravascular volume. We evaluated whether IVC area monitoring using an implantable wireless sensor provides a sensitive and timely marker of physiologic response to oral and intravenous (IV) loop diuretics in patients with HF.
Methods
We analysed patients enrolled in two prospective feasibility studies (FUTURE-HF and FUTURE-HF II) who completed 6-month follow-up after implantation of a passively excited wireless IVC sensor. Patients performed daily ambulatory IVC area measurements. Medication changes were prospectively recorded, and isolated loop diuretic adjustments were identified, including oral up titrations and IV diuretic administrations. For each diuretic event, a 5-day mean rolling window was applied to IVC area and it was evaluated from 14 days before to 14 days after the effective onset of therapy and expressed as percentage change relative to the onset of the medication change. Ensemble-averaged trajectories were constructed, and pre- versus post-titration trends were compared using Wilcoxon signed-rank testing.
Results
Sixty-five patients (mean age 66 years; 75% NYHA class III) contributed 28,333 daily IVC measurements and 296 medication adjustments, of which 60% involved loop diuretics. Thirty-two periods of isolated oral loop diuretic up titrations (27 patients) and 22 IV diuretic administrations (15 patients) were analysed. Oral diuretic intensification was followed by a decrease in IVC area across patients. Ensemble analysis demonstrated significant divergence between pre- and post-titration slopes beginning on day 2 (p<0.05). IV diuretic therapy produced larger and more rapid reductions in IVC area, reflecting greater potency, with significant post diuretic titration reductions in IVC area observed across ensemble trajectories (p<0.05, Figure 1). Over the first 6 months post-implant, we observed mean absolute IVC area decrease of 6.8% (p<0.05), consistent with physiological decongestion. Over the same period, no significant change was observed in mean body weight across patients (p>0.05).
Conclusions
Ambulatory implantable IVC monitoring provides a sensitive, real-time physiological measure of response to both oral and IV loop diuretics in patients with HF. These preliminary findings establish proof-of-physiology for IVC-based congestion monitoring and inform the development of IVC-guided diuretic titration strategies and randomized outcome trials.Diuretic Response in IVC SignalFor image description, please refer to the figure legend and surrounding text.