Early and timely recognition of congestion and decompensation may prevent heart failure hospitalisations and improve patient outcomes. But with the clinical signs and symptoms of fluid overload often difficult to elucidate on examination, emerging technological advancements in invasive and non-invasive haemodynamic monitoring are increasingly valuable, as consultant cardiologist Pardeep Jhund discusses.
Heart failure is a common condition that affects around 5% of the population in the UK and 64 million patients worldwide.1
It often develops insidiously, causing breathlessness or an inability to carry out activities of daily life. Fluid accumulates over several days and weeks and is often indolent until it becomes so severe that the patient must seek help. When this occurs, there is usually no option but to admit the individual to hospital and administer intravenous diuretics for the relief of fluid overload or congestion.
Heart failure reduces life expectancy but also places a considerable burden on healthcare systems globally. Patients are often hospitalised for many days, which contributes to healthcare costs.
Furthermore, hospital admissions for heart failure are associated with poorer outcomes. Therefore, preventing hospitalisations would benefit patients and healthcare systems by improving clinical outcomes and providing substantial cost savings.
Detecting and monitoring congestion
The signs and symptoms of congestion are often difficult to elucidate on examination. Therefore, there has been much interest in developing technologies to monitor the fluid status and determine whether the patient is developing congestion so that healthcare providers can intervene promptly and hopefully prevent hospitalisation.
- Invasive haemodynamic monitoring
Invasive haemodynamic monitoring of patients with heart failure is now possible. In a day-case procedure, a small sensor is placed in the pulmonary artery under local anaesthesia. The device communicates with a mobile reader, which can then relay telemetry data to the healthcare provider.
By monitoring pulmonary artery pressure and determining any increase, which is a sign of congestion, the healthcare team can intervene and suggest changes to the patient’s management, which might prevent further congestion and deterioration that would require hospitalisation.
Clinical trials and a meta-analysis of the previous randomised controlled trials have suggested that this technique can reduce hospitalisations for heart failure.2 However, the technique is costly and requires a specific set-up to monitor patients.
- Pacemakers and defibrillators
Pacemakers or implantable defibrillators have been able to monitor congestion for some time.3,4 These pacemakers use an algorithm that detects fluid in the chest alongside the general parameters recognised by the pacemaker.
By integrating these measures, the patient’s fluid status can be determined, and, again, healthcare systems can be alerted to impending congestion, thereby allowing physicians to intervene and reduce the risk of hospitalisation.
Unlike pulmonary artery pressure monitoring, there have been no large-scale randomised trials demonstrating that this method of monitoring congestion can reduce hospitalisations. A major disadvantage of this method is that it is also only valuable for patients needing a pacemaker.
Non-invasive monitoring
There has been much interest in non-invasive monitoring of fluid status and congestion in patients with heart failure. These methods could be less costly, more acceptable to patients and more straightforward to deploy on a larger scale.
Wearables that continuously measure thoracic impedance to determine if the patient is retaining fluid and becoming congested are available. The devices communicate the findings and alert the healthcare team and patient to any developing congestion via an app on a mobile device. However, they rely mainly on only one parameter for congestion.
Some innovations go one step further by only being worn twice daily for a few minutes rather than continuously. The sensors gather data on thoracic impedance, electrocardiogram and heart sounds, lung function and tidal volume, heart rate and respiratory rate, alongside other measures. The device then integrates these data into a measure of congestion, relayed to a Cloud-based system that can alert the patient and healthcare team.
A novel approach to congestion monitoring
At the University of Glasgow, UK, we have recently examined the effectiveness of one such novel cardiopulmonary wearable sensor in accurately measuring congestion compared to gold-standard clinical measures.5
The CONGEST-HF trial enrolled 66 patients across three cohorts: patients with heart failure receiving diuretics, haemodialysis patients and patients undergoing right heart catheterisation. There was good agreement between the device and our currently used measures of assessing congestion. Thoracic impedance and a measure of the heart sounds taken by the device could detect changes in weight in patients undergoing decongestion with intravenous diuretics.
We also found that thoracic impedance performed well compared with ultrasound assessment of the lung fluid when tracking the fluid removed during a dialysis session in patients with kidney failure.
Our results suggest that wearable devices that measure multiple parameters could potentially be very useful tools for monitoring congestion in patients with heart failure. Ultimately, we hope to show that these technologies can effectively prevent hospitalisations.
Author
Pardeep Jhund MBChB MSc PhD
Professor of cardiology and epidemiology, School of Cardiovascular & Metabolic Health, University of Glasgow, and honorary consultant cardiologist at the Queen Elizabeth University Hospital, Glasgow, UK
References
- Savarese G et al. Global burden of heart failure: a comprehensive and updated review of epidemiology. Cardiovasc Res 2023;118(17):3272–87.
- Clephas PRD et al. Efficacy of pulmonary artery pressure monitoring in patients with chronic heart failure: a meta-analysis of three randomized controlled trials. Eur Heart J 2023;44(37):3658–68.
- Gardner RS et al. HeartLogic Multisensor Algorithm Identifies Patients During Periods of Significantly Increased Risk of Heart Failure Events: Results From the MultiSENSE Study. Circulation: Heart Failure 2018;11(7):e004669.
- Conraads VM et al. Sensitivity and positive predictive value of implantable intrathoracic impedance monitoring as a predictor of heart failure hospitalizations: the SENSE-HF trial. Eur Heart J 2011;32:2266–73.
- Curtain JP et al. Measuring congestion with a non-invasive monitoring device in heart failure and haemodialysis: CONGEST-HF. Eur J Heart Fail 2024;26(6):1383–92.
