Original ArticleElimination of central sleep apnea by cardiac valve replacement: a continuous follow-up study in patients with rheumatic valvular heart disease
Introduction
Sleep-disordered breathing (SDB) may be classified into central sleep apnea (CSA) and obstructive sleep apnea (OSA). SDB, especially CSA, occurs frequently in patients with chronic heart failure (CHF). One large-scale study showed that SDB was present in 76% (40% CSA, 36% OSA) of patients with symptomatic CHF [1]. Of the two types of sleep apnea, studies have shown that OSA is implicated as a cardiovascular risk factor, and that CSA is an end-result of deteriorating cardiac function [2], [3], [4], [5].
Several case reports strongly suggest that heart valve repair or replacement may lead to improvements in SDB [6], [7], [8], [9]. Tomcsanyi and Yasuma reported that CSA events were substantially reduced after successful cardiac valve replacement (CVR) [7], [9], and Collop and Mansfield found an improvement in CSA after successful heart transplant [10], [11]. Abe [12] investigated 74 patients with valvular heart disease and reported significant improvements in CSA index (CSAI), pulmonary capillary wedge pressure (PCWP), and mean pulmonary artery pressure (PAP), and no changes in OSA index (OSAI) 14 days post heart-valve repair.
Although heart valve treatment has been reported to eliminate CSA or cause a shift from CSA to OSA, the mechanisms responsible for these effects are not fully understood. Some researchers [8], [13], [14], [15], [16], [17] have suggested that the decrease in CSA may be related to enhanced lower partial pressure of arterial CO2 (PaCO2) and reduced lung-to-ear circulation time, whereas others [12] have considered that the improvements in CSA or shift from CSA to OSA may be the result of improved cardiac function.
In our previous study, we demonstrated that 38.8% of patients with rheumatic valvular heart disease (RVHD) also suffered from SDB [18]. We hypothesized that CVR surgery may affect CSA and OSA in patients with RVHD and SDB, and that the changes in SDB may be due to an improvement of heart function, chemosensitivity and hemodynamic circulation. In the current prospective study, we therefore investigated the dynamic changes in the various parameters at three, six, and 12 months after heart valve surgery in patients with RVHD and SDB.
Section snippets
Subjects and study design
Data were collected from 262 patients with RVHD who were admitted to the Cardiothoracic Surgery Department for CVR. The inclusion criteria were: (i) age 18–70 years; (ii) symptomatic stable heart failure, New York Heart Association (NYHA) class ⩾II despite optimal drug therapy; (iii) diagnosis of RVHD based on the 2004 World Health Organization (WHO) criteria for the diagnosis of rheumatic fever and rheumatic heart disease [19]; (iv) indications for valvular replacement surgery met the American
Results
Of 39 patients who completed follow-up assessments, there were 24 with CSA and 15 with OSA. The comparison of clinical and sleep parameters baselines is shown in Table 1. There were no significant differences in age, LVEF, ESS score, AHI, mean SpO2, minimum SpO2, sleep efficiency, or PaO2 between the CSA and OSA patients. Compared with the OSA patients, CSA patients experienced a higher prevalence of atrial fibrillation, higher NYHA class, lower BMI, shorter 6-MWD, larger left atrial diameter
Discussion
There were no differences in the severity of SDB between CSA and OSA patients. However, compared with OSA patients, CSA patients had worse baseline heart function (represented by NYHA class, plasma BNP, 6-MWD and LAD), as well as enhanced chemosensitivity (represented by blood gas) and disordered hemodynamics (represented by LFCT). In addition, there was also a higher prevalence of atrial fibrillation in CSA patients. These findings were in accordance with the results of previous studies [1],
Conclusions
The results of the present study demonstrate that CSA patients with RVHD had a worse baseline cardiac function, enhanced chemosensitivity, and disordered hemodynamic circulation compared with OSA patients with RVHD. CSA was eliminated after CVR; however, there were no post-CVR changes noted in OSA. The elimination of CSA is thought to be associated with the combined effects of improvement of overall cardiac function (fundamental factor), normalized chemosensitivity, and hemodynamics (direct
Funding sources
This study was supported by the Priority Academic Program of Jiangsu Higher Education Institutions (Grants JX10231801) and Jiangsu Provincial Department of Education (Grants CXLX12_0557).
Conflict of interest
The ICMJE Uniform Disclosure Form for Potential Conflicts of Interest associated with this article can be viewed by clicking on the following link: http://dx.doi.org/10.1016/j.sleep.2014.02.007.
References (28)
- et al.
Disappearance of periodic breathing after heart operations
J Thorac Cardiovasc Surg
(1994) Cheyne–Stokes ventilation converting to obstructive sleep apnea following heart transplantation
Chest
(1993)- et al.
The effect of successful heart transplant treatment of heart failure on central sleep apnea
Chest
(2003) - et al.
2008 focused update incorporated into the ACC/AHA 2006 guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to revise the 1998 guidelines for the management of patients with valvular heart disease). Endorsed by the society of cardiovascular anesthesiologists, society for cardiovascular angiography and interventions, and society of thoracic surgeons
J Am Coll Cardiol
(2008) - et al.
Prevalence of sleep-disordered breathing in diastolic heart failure
Chest
(1997) - et al.
Sleep-disordered breathing occurs frequently in stable outpatients with congestive heart failure
Chest
(2005) - et al.
Sleep-disordered breathing in patients with symptomatic heart failure: a contemporary study of prevalence in and characteristics of 700 patients
Eur J Heart Fail
(2007) - et al.
Increased mortality associated with Cheyne–Stokes respiration in patients with congestive heart failure
Am J Respir Crit Care Med
(1996) - et al.
Central sleep apnea in left ventricular dysfunction: prevalence and implications for arrhythmic risk
Circulation
(2003) - et al.
Prospective study of obstructive sleep apnea and incident coronary heart disease and heart failure: the sleep heart health study
Circulation
(2010)