Breathing Exercise Against Dyspnoea in Heart Failure Patients to Improve Chemosensitivity

An exaggerated ventilatory response (minute ventilation, V̇E) to exercise relative to exhaled carbon dioxide (V̇CO2) is common in heart failure (HF) patients with reduced as well as preserved left ventricular ejection fraction (HFrEF, HFpEF). Severity of this exaggerated response is associated with poor prognosis. This response may be triggered by pulmonary congestion and peripheral muscle myopathy. A vicious circle is fuelled by hypersensitivity of chemoreceptors to hypercapnia and sympathetic nervous hyperactivity, resulting in hyperventilation (low PaCO2). Low PaCO2 is predictive of mortality in these patients. PaCO2 can be increased acutely, e.g. by apnoea. Also, nasal breathing has been found to reduce the V̇E/V̇CO2 slope during exercise compared to oral breathing. Three previous slow breathing studies in HFrEF patients have had encouraging results with regard to reducing sympathetic activity, reflected in lowered arterial (pulmonary) blood pressure and increased EF. The investigators hypothesise that a 12-week training with nasal slow breathing followed by end-expiratory apnoea based on education, centre-based introduction and home-based 15 min/day breathing training will be effective at reducing the exaggerated ventilatory response to exercise. A total of 68 patients with stable HF seen at the HF clinics of the Inselspital (34 HFrEF, 34 HFpEF) will be randomised to the breathing intervention or usual care. Primary outcome will be V̇E/V̇CO2 slope at 12 weeks. If breathing training successfully ameliorates the exaggerated ventilatory response and perception of dyspnea during exercise, it offers an attractive tele-health based add-on therapy that may add to or even amplify the beneficial effects of exercise training.