Chemoreflexsensitivity in chronic heart failure patients

Patients with heart failure are characterised by a disturbed sympathovagal balance, as could be shown by analyses of heart rate variability and baroreflexsensitivity. Furthermore, the modulation of ventilation is disturbed in those patients with an increased ventilation volume following the inhalation of hypoxic gas. This study should evaluate, whether heart failure patients have a decreased hyperoxic chemoreflexsensitivity associated with an increased rate of ventricular arrhythmias.

Into this study, 49 consecutive patients were enrolled. Of these, 23 suffered from heart failure; the remaining had no evidence of heart failure and a normal left ventricular ejection fraction. All patients were investigated by analysing the reduction of heart rate following inhalation of pure oxygen. The difference of RR-interval divided by the difference of the venous oxygen partial pressure both before and after oxygen inhalation resulted in the chemoreflexsensitivity. Patients with heart failure showed a significantly decreased chemoreflexsensitivity compared to those without (2.62+/-1.85 vs. 5.80+/-6.37 ms/mmHg, P<0.05). Of patients with heart failure, 69.6% had a decreased chemoreflexsensitivity below 3 ms/mmHg, in contrast to only 38.5% of the control group. Patients with decreased chemoreflexsensitivity showed significantly more non-sustained ventricular tachycardias (46 vs. 4%, P<0.05) during Holter ECG.

Patients with heart failure show a significantly decreased hyperoxic chemoreflexsensitivity. A decreased chemoreflexsensitivity is associated with an increased rate of non-sustained ventricular tachycardias. This may be related to an increased sympathetic tone in these patients. The chemoreflexsensitivity may be important in arrhythmic risk stratification of patients with heart failure.