Ventricular assist devices and sleep-disordered breathing

Central Sleep Apnea and Cardiovascular Disease State-of-the-Art

Central sleep apnea (CSA), a rare polysomnographic finding in the general population, is prevalent in certain cardiovascular conditions including systolic and diastolic left ventricular dysfunction, atrial fibrillation, coronary artery disease, carotid artery stenosis, stroke and use of certain cardiac-related medications. Polysomnographic findings of CSA with adverse cardiovascular impacts include nocturnal hypoxemia and arousals, which can lead to increased sympathetic activity both at night and in the daytime. Among cardiovascular diseases, CSA is most prevalent in patients with left ventricular systolic dysfunction; a large study of more than 900 treated patients has shown a dose dependent relationship between nocturnal desaturation and mortality. Multiple small randomized controlled trials have shown mitigation of sympathetic activity when CSA is treated with nocturnal oxygen, continuous positive airway pressure and adaptive servoventilation. However, two early randomized controlled trials with positive airway pressure devices have shown either neutral effect on survival or excess premature mortality in the active treatment arm, compared to untreated CSA. In contrast, the results of the most recent trial using an advanced adaptive servoventilation device showed improved quality of life and no signal for mortality suggesting that treatment of CSA was at least safe. In addition to positive airway pressure devices, multiple medications have been shown to improve CSA, but no long-term trials of pharmacologic therapy have been published. Currently, phrenic nerve stimulation is approved for treatment of CSA, and the results of a randomized controlled trial showed significant improvement in sleep metrics and quality of life.

Ventricular assist devices and sleep-disordered breathing-A mechanical heart stimulating a sleepy brain

Sleep-disordered breathing, including obstructive sleep apnea (OSA) and central sleep apnea (CSA), is common in severe heart failure (HF) patients. There is limited data on the effect of left ventricular assist devices (LVAD) on sleep apnea. We performed a retrospective review of 350 durable LVAD patients and found 5 with a history of pre- and post-LVAD sleep studies. All five patients had OSA, and three had concomitant CSA. We observed reduced apnea-hypopnea index following LVAD placement. This was due to a near abolishment of CSA in three mixed sleep apnea patients-as seen by a central apnea index improvement from an average of 25.9 ± 13.1 to 1.4 ± 2.5 events per hour (p = 0.063). LVAD placement was associated with an increase in thermodilution cardiac output from 2.7 ± 0.6 to 4.1 ± 1.1 L/min (p = 0.014). These findings support chemoreception physiology seen in patients with poor circulation and the effect of restoring this circulation with LVAD support.

Effect of phrenic nerve stimulation on patients with central sleep apnea: A meta-analysis

Patients with central sleep apnea (CSA) have a lower quality of life and higher morbidity and mortality. Phrenic nerve stimulation (PNS) is a novel treatment for CSA that has been shown to be safe. However, the effects of PNS on sleep changes are still under debate. This meta-analysis was performed to evaluate the efficacy of PNS in patients with CSA. PubMed, Scopus, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL) and Web of Science databases were searched for relevant studies published. We performed random-effects meta-analyses of the changes in apnea-hypopnea index (AHI), central apnea index (CAI), Arousal Index, percent of sleep with O2 saturation <90% (T90), Epworth Sleepiness Scale (ESS) and sleep efficiency. Ten studies with a total of 580 subjects were analyzed. Overall meta-analysis showed AHI [SMD: -2.24, 95% confidence interval (CI): was -3.11 to -1.36(p＜0.00001)], CAI [SMD: -2.32, 95% CI: -3.17 to -1.47 (p＜0.00001)] and Arousal Index (p = 0.0002, SMD (95% CI) -1.79 (-2.74 to -0.85)) significantly reduced after PNS. No significant changes were observed in T90, ESS and sleep efficiency (p > 0.05). Meta-analysis of observational studies demonstrated AHI, CAI and Arousal Index had a decreasing trend between before and after PNS (all, p＜0.05). However, ESS and T90 did not change significantly after PNS (p > 0.05). Meta-analysis of RCTs showed that CSA patients had trends of a lower AHI (I2 = 0%), CAI (I2 = 74%), Arousal Index (I2 = 0%), T90 (I2 = 0%) and ESS (I2 = 0%) after PNS (all, p＜0.05). The use of PNS appears to be safe and feasible in patients with CSA. However, larger, independent RCTs are required to investigate the efficacy and long-term effect of PNS and more attention should be paid to T90 and ESS.

Inpatient Cardiac Rehabilitation of LVAD Patients-Updated Recommendations from the Working Group of the German Society for Prevention and Rehabilitation of Cardiovascular Diseases

Cardiac rehabilitation physicians are faced to an increasing number of heart failure patients supported by left ventricular assist devices (LVAD). Many of these patients have complex medical issues and prolonged hospitalizations and therefore need special cardiac rehabilitation strategies including psychological, social, and educational support which are actually poorly implemented.Cardiac rehabilitation with clear guidance and more evidence should be considered as an essential component of the patient care plan especially regarding the increasing number of destination patients and their long-term follow-up.In this article the working group for postimplant treatment and rehabilitation of LVAD patients of the German Society for Prevention and Rehabilitation of Cardiovascular Diseases has summarized and updated the recommendations for the cardiac rehabilitation of LVAD patients considering the latest literature.