A protocol was originally designed to study breathing control during and following cardiac arrest in humans, taking advantage of the period of pulseless ventricular fibrillation (PVF) produced while testing a newly implanted cardioverter-defibrillator device. A patient aged in his 60s with New York Heart Association class III heart failure (HF) (left ventricular ejection fraction of 25%) who was originally part of this study displayed permanent periodic breathing (PB) and was then excluded from the final data analysis; his response is presented in this report. The 8- to 9-s PVF was incidentally produced during the ascending phase of a PB cycle, followed by another 12-s recovery period of low BP. PVF and its recovery had no effect on PB characteristics (period or amplitude). This occurred despite a profound change in Paco2, cerebral blood flow, and perfusion of the carotid bodies. It is concluded that PB in patients with HF could be produced by primary oscillations originating from the central pattern generator.