Circadian rhythms in pump parameters of patients on contemporary left ventricular assist device support

BACKGROUND

Algorithms to monitor pump parameters are needed to further improve outcomes after left ventricular assist device (LVAD) implantation. Previous research showed a restored circadian rhythm in pump parameters in patients on HeartWare (HVAD) support. Circadian patterns in HeartMate3 (HM3) were not studied before, but this is important for the development of LVAD monitoring algorithms. Hence, we aimed to describe circadian patterns in HM3 parameters and their relation to patterns in heart rate (HR).

METHODS

18 HM3 patients were included in this study. HM3 data were retrieved at a high frequency (one sample per 1 or 2 h) for 1-2 weeks. HR was measured using a wearable biosensor. To study overall patterns in HM3 parameters and HR, a heatmap was created. A 24-h cosine was fitted on power and HR separately. The relationship between the amplitude of the fitted cosines of power and HR was calculated using Spearman correlation.

RESULTS

A lower between patient variability was found in power compared with flow and PI. 83% of the patients showed a significant circadian rhythmicity in power (p < 0.001-0.04), with a clear morning increase. All patients showed significant circadian rhythmicity in HR (p < 0.001-0.02). The amplitudes of the circadian rhythm in power and HR were not correlated (Spearman correlation of 0.32, p = 0.19).

CONCLUSIONS

A circadian rhythm of pump parameters is present in the majority of HM3 patients. Higher frequency pump parameter data should be collected, to enable early detection of complications in the future development of predictive algorithms.

Should we continue trusting bodyweight for HF volume telemonitoring?

Background

Telemonitoring of body weight, blood pressure and heart rate has extensively been used to facilitate early recognition of heart failure (HF) decompensations in order to prevent hospital admissions. Mixed results have been shown by different clinical trials regarding the effectiveness of telemonitoring in HF management. It is recognized that HF decompensation starts with an increase in intra cardiac filling pressure. The relationship between daily pulmonary artery pressure (PAP) values measurements and body weight is not completely established.

Purpose

To study the relationship between daily changes in body weight and invasive daily measurements such as diastolic PAP assessed by a pulmonary artery pressure sensor (CardioMEMS).

Methods

Eleven patients with left sided chronic HF implanted with a CardioMEMS device were included in the study (age 75±9 years, ejection fraction 52±10%). Daily measured body weight and pulmonary artery pressures were recorded during 6 months. The primary endpoint was to assess the correlation between the “PAP deviation” – defined as the difference between daily diastolic PAP and mean diastolic PAP over the study period – and the “weight deviation” – defined as the difference between daily body weight determinations and mean body weight.

Results

During the 6-months study period, 1766 body weight and diastolic PAP measurements were recorded (158±47 daily measurements per patient). We found a weak although significant correlation between changes in body weight and changes in diastolic PAP (Figure 1). When analyzing data individually, no patient presented a strong correlation between the two variables.

Conclusions

Our results suggest that repeated measurements of body weight have limited utility in detecting left sided heart failure decompensations. More complex and patient-specific thresholds for the biometric measurements are needed to improve early detection of decompensation in HF patients. For the development of early detection algorithms, we may learn from invasive methods, such as the CardioMEMS device.

Funding Acknowledgement

Type of funding sources: None.