Heart failure and sleep-disordered breathing: mechanisms, consequences and treatment

This review examines the recently published articles pertaining to sleep-disordered breathing (SDB) and heart failure.

The recent findings can be classified into pulmonary, upper airway and treatment trials. Pulmonary complications of heart failure include loss of surfactant, increased pulmonary dry weight and reduced lung volume, which are likely to increase plant gain and thus predispose to central sleep apnea with Cheyne-Stokes respiration. Upper airway narrowing in normal individuals has been shown to occur with lower limb compression and the supine body position, thus suggesting that rostral fluid shifts may narrow the upper airway and aggravate obstructive sleep apnea. Extrapolating this to congestive heart failure (CHF), it is possible that CHF fluid status may impact upon obstructive sleep apnea severity. Following the Canadian Continuous Positive Airway Pressure for Patients with Central Sleep Apnoea and Heart Failure trial, further SDB intervention studies have been reported using adaptive servo-ventilation. Although encouraging, small, short-term studies are discussed, however long-term randomized trials with objective cardiac outcomes are still lacking.

The relationship between CHF and SDB is likely to be bidirectional, CHF impacting on SDB severity and vice versa. Identification of SDB in the CHF population appears to be important as it is probably associated with greater mortality, but whether SDB intervention significantly influences CHF survival still remains to be determined.