Safety and performance of a novel implantable sensor in the inferior vena cava under acute and chronic intravascular volume modulation

ABSTRACT Aims The management of congestion is one of the key treatment targets in heart failure. Assessing congestion is, however, difficult. The purpose of this study was to investigate the safety and dynamic response of a novel, passive, inferior vena cava (IVC) sensor in a chronic ovine model. Methods and results A total of 20 sheep divided into three groups were studied in acute and chronic in vivo settings. Group I and Group II included 14 sheep in total with 12 sheep receiving the sensor and two sheep receiving a control device (IVC filter). Group III included an additional six animals for studying responses to volume challenges via infusion of blood and saline solutions. Deployment was 100% successful with all devices implanted; performing as expected with no device‐related complications and signals were received at all observations. At similar volume states no significant differences in IVC area normalized to absolute area range were measured (55 ± 17% on day 0 and 62 ± 12% on day 120, p = 0.51). Chronically, the sensors were completely integrated with a thin, reendothelialized neointima with no loss of sensitivity to infused volume. Normalized IVC area changed significantly from 25 ± 17% to 43 ± 11% (p = 0.007) with 300 ml infused. In contrast, right atrial pressure required 1200 ml of infused volume prior to a statistically significant change from 3.1 ± 2.6 mmHg to 7.5 ± 2.0 mmHg (p = 0.02). Conclusion In conclusion, IVC area can be measured remotely in real‐time using a safe, accurate, wireless, and chronic implantable sensor promising to detect congestion with higher sensitivity than filling pressures. A wireless inferior vena cava (IVC) sensor was implanted in sheep followed by experimental sensor assessment at acute and chronic time points including safety, signal, and sensor performance during manipulation of volume status. All sensors were safe and provided signal at all time points. The performance study (bottom right) showed that the sensors responded equally well to volume infusion (100 ml per data point) at acute and chronic observations, demonstrating the sensor's ability to detect volume accumulation consistently and reliably. Furthermore, IVC area changes were more sensitive than the corresponding changes in cardiac filling pressures, that is right atrial pressure (RAP) during manipulation of volume status. [Correction added on 30 May 2023, after first online publication: The graphical image has been corrected in this version.]