Methodology for the nocturnal cardiac arrhythmia ancillary study of the ADVENT-HF trial in patients with heart failure with reduced ejection fraction and sleep-disordered breathing.

Background: Sleep disordered breathing (SDB) may trigger nocturnal cardiac arrhythmias (NCA) in patients with heart failure with reduced ejection fraction (HFrEF). The NCA ancillary study of the ADVENT-HF trial will test whether, in HFrEF-patients with SDB, peak-flow-triggered adaptive servo-ventilation (ASVpf) reduces NCA. To this end, accurate scoring of NCA from polysomnography (PSG) is required. Objective: To develop a method to detect NCA accurately from a single-lead electrocardiogram (ECG) recorded during PSG and assess inter-observer agreement for NCA detection. Methods: Quality assurance of ECG analysis included training of the investigators, development of standardized technical quality, guideline-conforming semi-automated NCA-scoring via Holter-ECG software and implementation of an arrhythmia adjudication committee. To assess inter-observer agreement, the ECG was analysed by two independent investigators and compared for agreement on premature ventricular complexes (PVC) /h, premature atrial complexes/h (PAC) as well as for other NCA in 62 patients from two centers of the ADVENT-HF trial. Results: The intraclass correlation coefficients for PVC/h and PAC/h were excellent: 0.99 (95%- confidence interval [CI]: 0.99-0.99) and 0.99 (95%-CI: 0.97-0.99), respectively. No clinically relevant difference in inter-observer classification of other NCA was found. The detection of non-sustained ventricular tachycardia (18% versus 19%) and atrial fibrillation (10% versus 11%) was similar between the two investigators. No sustained ventricular tachycardia was detected. Conclusion: These findings indicate that our methods are very reliable for scoring NCAs and are adequate to apply for the entire PSG data set of the ADVENT-HF trial.

Continuity of care for women with breast cancer: a survey of the views and experiences of patients, carers and health care professionals.

PURPOSE OF THE RESEARCH: The need for continuity of care in the management of women diagnosed with breast cancer is important yet challenging. The aim was twofold; to explore 1) the concept of continuity of care from the perspectives of women diagnosed with breast cancer, their carers and their health care professionals (HCPs), 2) actual experiences amongst these three groups relating to continuity of care. METHODS AND SAMPLE: A three-phase cross-sectional survey was conducted involving eight focus group interviews with women who had been diagnosed with breast cancer (n = 47) and structured questionnaires to both carers (n = 33) and HCPs (n = 44). Data were analysed according to three categories of continuity of care; relational, informational and managerial. KEY RESULTS: According to the patients: 'Continuity of Care' is the continuous care over time; it involves the relationship between the HCP and the patient. It is not just a follow-up review. The relationship is built on trust, loyalty and constancy. The perception is that the providers of care know you, know your case history and your future care is agreed on.' Across all phases of the study the three categories of continuity of care were identified but there were differences as to the weight different groups placed on them. Continuity of care was reported to be achieved for the majority of the respondents across all three samples however deficiencies in the service were identified. CONCLUSION: The results provide an opportunity to improve service; recommendations have been made and steps to implementation taken.

Influence of Cheyne-Stokes respiration on cardiovascular oscillations in heart failure.

In patients with congestive heart failure, Cheyne-Stokes respiration is accompanied by oscillations in blood pressure and heart rate at a very low frequency. It is not known whether these cardiovascular oscillations are primarily related to oscillations in ventilation or oxyhemoglobin saturation. We hypothesized that abolition of the ventilatory oscillations of Cheyne-Stokes respiration by CO2 inhalation would eliminate accompanying oscillations in blood pressure and heart rate but that elimination of hypoxic dips by supplemental O2 would not. We studied 10 subjects with heart failure and Cheyne-Stokes respiration during sleep using frequency spectral analysis. During Cheyne-Stokes respiration, heart rate and blood pressure oscillated in association with respiratory oscillations at very low frequency. Inhalation of CO2 abolished Cheyne-Stokes respiration and associated oscillations in both blood pressure and heart rate. In contrast, inhalation of O2 sufficient to eliminate hypoxic dips had no significant effect on Cheyne-Stokes respiration, blood pressure (n = 6), or heart rate (n = 5). We conclude that ventilatory oscillations during Cheyne-Stokes respiration rather than oscillations in oxygenation per se powerfully induce heart rate and blood pressure oscillations. Cheyne-Stokes respiration is therefore one of the mechanisms that contributes to the very low-frequency oscillations in heart rate and blood pressure observed in patients with heart failure.