Provocation of ventricular ectopy by cheyne-stokes respiration in patients with heart failure.

Study Objectives: Previous reports have suggested an association between Cheyne-Stokes respiration with central sleep apnea (CSR-CSA) and ventricular ectopy, but there has been relatively little evidence of a cause-effect relationship. The objective of this study was to determine whether CSR-CSA directly provokes ventricular ectopy and, if so, whether it is associated with any particular phase of the CSR-CSA breathing cycle.

Design: We compared the frequency of ventricular premature beats (1) between the apneic and hyperpneic phases of CSR-CSA, (2) between periods of CSR-CSA and periods of regular breathing during sleep, and (3) in response to the elimination of CSR-CSA by administration of a low concentration of inhaled CO2.

Respiratory modulation of heart rate and blood pressure during Cheyne-Stokes respiration.

Cheyne-Stokes respiration (CSR) is a form of periodic breathing associated with oscillations in heart rate (HR) and blood pressure (BP), which have previously been attributed to the effects of intermittent hypoxia and arousals from sleep. We herein review the major findings from a series of experiments, in which we explored the possibility that the ventilatory oscillations of CSR can independently modulate HR and BP. Using frequency spectral analysis, we showed that CSR in patients with heart failure causes oscillations in HR and BP that are eliminated by abolition of ventilatory oscillations, but persist during administration of supplemental O2 sufficient to prevent hypoxia.

Relationship of sleep apnea to functional capacity and length of hospitalization following stroke.

Study Objectives: Recent evidence indicates that sleep apnea is common in patients with stroke. We hypothesized that the presence of sleep apnea among stroke patients would be associated with a greater degree of functional disability and longer hospitalization following stroke.

Design: Prospective study.