Abstract
Heart rate variability (HRV) is a crucial indicator of cardiovascular health. Low HRV is correlated with disease severity and mortality in heart failure. Heart rate increases and decreases with each breath in normal physiology termed respiratory sinus arrhythmia (RSA). RSA is highly evolutionarily conserved, most prominent in the young and athletic and is lost in cardiovascular disease. Despite this, current pacemakers either pace the heart in a metronomic fashion or sense activity in the sinus node. If RSA has been lost in cardiovascular disease current pacemakers cannot restore it. We hypothesized that restoration of RSA in heart failure would improve cardiac function. Restoration of RSA in heart failure was assessed in an ovine model of heart failure with reduced ejection fraction.
Conscious 24hr recordings were made from 3 groups, RSA paced (n= 6), monotonically paced (n = 6) and heart failure time control (n = 5). Real-time blood pressure, cardiac output, heart rate and diaphragmatic EMG was recorded in all animals. Respiratory modulated pacing was generated by a proprietary device (Ceryx Medical) to pace the heart with real-time respiratory modulation. RSA pacing substantially increased cardiac output by 1.4 L/min (20%) compared to contemporary (monotonic) pacing. This increase in cardiac output led to a significant decrease in apnoeas associated with heart failure, reversed cardiomyocyte hypertrophy, and restored the T-tubule structure that is essential for force generation. Re-instating RSA in heart failure improves cardiac function through mechanisms of reverse re-modelling; the improvement observed is far greater than that seen with current contemporary therapies. These findings support the concept to re-instate RSA as a regime for patients who require a pacemaker.
Conscious 24hr recordings were made from 3 groups, RSA paced (n= 6), monotonically paced (n = 6) and heart failure time control (n = 5). Real-time blood pressure, cardiac output, heart rate and diaphragmatic EMG was recorded in all animals. Respiratory modulated pacing was generated by a proprietary device (Ceryx Medical) to pace the heart with real-time respiratory modulation. RSA pacing substantially increased cardiac output by 1.4 L/min (20%) compared to contemporary (monotonic) pacing. This increase in cardiac output led to a significant decrease in apnoeas associated with heart failure, reversed cardiomyocyte hypertrophy, and restored the T-tubule structure that is essential for force generation. Re-instating RSA in heart failure improves cardiac function through mechanisms of reverse re-modelling; the improvement observed is far greater than that seen with current contemporary therapies. These findings support the concept to re-instate RSA as a regime for patients who require a pacemaker.
| Original language | English |
|---|---|
| Article number | 4 |
| Journal | Basic Research in Cardiology |
| Volume | 117 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 1 Feb 2022 |
Bibliographical note
Funding Information:Open Access funding enabled and organized by CAUL and its Member Institutions. The authors would like to gratefully acknowledge generous funding from the Health Research Council of New Zealand, Ceryx Medical Ltd, the University of Auckland Faculty Research Development Fund, the National Heart Foundation of New Zealand, the Sidney Taylor Trust and the Maurice and Phyllis Paykel Trust.
