P1790Cardio-respiratory coupling in heart failure

Abstract

Background: The nature of cardio-respiratory interaction in heart failure is still unknown. However, coupling of cardiac and respiratory systems is mediated by vagal cardiac nerve and heart failure is recognized as a state of suppressed parasympathetic activity. Purpose: To find properties of cardio-respiratory coupling in heart failure we examined bidirectional interaction of cardiac (RR intervals) and respiratory signal in three groups of heart failure patients: with sinus rhythm (HF-Sin), with ventricular extra systoles (HF-VES), with atrial fibrillation (HF-AF) and in healthy control subjects. Methods: We included patients with heart failure and an indication for implantable cardioverter defibrillator or cardiac resynchronization therapy device implantation. ECG and respiratory signals were simultaneously acquired during 20 minutes in supine position at spontaneous breathing frequency before implantation. We used coherence, Granger causality and cross-sample entropy analysis as complementary measures of bidirectional interactions between RR intervals and respiratory rhythm. Results: In heart failure patients with arrhythmias (HF-VES and HF-AF) there is no coherence between signals (p<0.01), while in HF-Sin it is reduced (p<0.01), compared with control subjects. In all heart failure groups causality between signals is diminished, but with significantly stronger causality of RR signal in respiratory signal in patients with both types of arrhythmias. Cross sample entropy analysis revealed that in HF-Sin and HF-VES patient synchrony from RR to respiratory signal increased, compared with control and HF-AF groups. Only in HFVES group significantly increased synchrony from respiratory to RR signal is obtained. Conclusions: These results suggest that there are two different forms of cardiorespiratory coupling and both of them are altered in heart failure patients. We found reduction of respiratory sinus arrhythmia in HF-Sin and its withdrawal in HFVES and HF-AF patients. Contrary, in HF-Sin and HF-VES patients bidirectional synchrony increased, probably as consequence of some dominant compensatory mechanisms.