2021, Number 4
The impact of using a mandibular advancement device in cardiovascular disorders related to obstructive sleep apnea
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Language: English/Spanish [Versión en español]
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ABSTRACT
Introduction: cardiovascular diseases have a high prevalence. Likewise, the prevalence of sleep breathing disorders in chronic heart failure patients is very high. Objective: to analyze the impact of using a mandibular advancement device (MAD) in patients with a history of previous heart failure. Material and methods: an extensive online search was performed on the MeSH descriptors "occlusal splints", "sleep apnea, obstructive" and "heart failure". Results: the severity of the sleep breathing disorder varies according to the severity of the cardiovascular disease. Discussion: the harmful effects of the obstructive sleep apnea (OSA) on the cardiovascular system include intermittent chronic hypoxia and great inspiratory efforts that overload the myocardium, thus affecting its structure and function. The MAD treatment can reduce the severity of the OSA and reduces intrathoracic pressure as it keeps the upper airway open. Conclusions: prevention of complications in cardiovascular patients with OSA is crucial and it is related to the prevention and treatment of respiratory disorders.INTRODUCTION
Cardiovascular diseases have a high prevalence.1 Similarly, the prevalence of sleep breathing disorders in chronic heart failure patients is very high.1,2 According to Oldenburg et al.,2 nocturnal oxygen desaturation is very common in chronic heart failure patients, so the pulse oximeter acts as a triage tool.
Some studies have established that systolic pressure is higher in obstructive sleep apnea (OSA) patients. For example, Archontogeorgis et al.3 showed that the risk of cardiovascular morbidity and mortality increases as the severity of OSA increases. For their part, Bitter et al.1 established that the symptoms and severity of sleep apnea vary before and after heart failure.
Often OSA is underdiagnosed in patients with previous heart disease since they often remain asymptomatic. However, it has been observed that there is a possible correlation between OSA and previous heart failure, independent of the majority of known associated factors.4 In this sense, Bitter et al.1 state that the symptoms and severity of sleep breathing disorder vary before and after heart failure. Similarly, the authors affirm that OSA is a frequent comorbidity in patients with underlying heart disease, which worsens their prognosis.
Oldenburg et al.2 established that the sleep breathing disorders diagnosis should be a routine activity in the evaluation and follow-up of heart problems patients since both are interrelated (Figure 1). Furthermore, whether a one-night sleep study is enough to adequately classify a respiratory disorder type and severity is unknown. According to these authors, the severity of sleep breathing disorders will vary according to the severity of the existing cardiac pathology: if the heart failure worsens substantially, respiratory and central events will increase.
Additionally, in recent years the development of the use of mandibular advancement devices (MAD) has proven to be a viable alternative treatment, and it has gained popularity in the treatment of mild to moderate OSA since it is a simple treatment with high adherence to patients and more cost-effective than continuous positive airway pressure (CPAP) or other techniques such as uvulopalatopharyngoplasty.4 Therefore, based on the existing scientific literature, this work aims to analyze the impact of using a MAD in patients with a history of previous heart failure.
MATERIAL AND METHODS
In January 2020, an electronic search was carried out in the Medline database through the PubMed search engine, for which different search strategies were applied using the keywords "mandibular advancement device" and the MeSH descriptors "occlusal splints", "sleep apnea, obstructive" and "heart failure" combined with each other with the AND operator. Inclusion criteria: articles published in English in the last 10 years about OSA treatment employing a MAD in patients with concomitant heart disease.
RESULTS
The initial electronic search yielded 205 results. After applying the inclusion criteria and screening after reading the abstracts, seven articles were selected, of which three were discarded because they did not provide relevant information about the study topic. Finally, four articles were included in the present study,5-8 which were exhaustively analyzed.
According to the existing literature, treating respiratory disorders is essential to minimize added risks in patients with previous cardiac disease. The use of MAD increases and stabilizes the dimension of the pharyngeal airway, generating a direct beneficial effect on cardiac load and reducing the OSA, OSA-induced hypoxemia, and excitations.
DISCUSSION
The harmful effects induced by the OSA on the cardiovascular system involve two components: first, the chronic intermittent hypoxia, which produces a sympathetic overactivation; second, the considerable negative intrathoracic pressures during inspiratory efforts. This overloads the myocardium, alters its structure and function, and leads to increased sympathetic activity (Figure 2).5 A study by Dal-Fabbro et al.6 stated that after three months of MAD treatment, the patients showed an increase in high frequency (parasympathetic) and reduction in low frequency (sympathetic). This finding suggests that the use of MAD has a positive systemic effect. Eskafi et al.7 pointed out that congestive heart failure (CHF) is associated with elevated levels of circulating brain natriuretic peptide (BNP). In CHF patients, high plasma BNP levels are associated with an increased risk of sudden death and strongly predict mortality.
The OSA is a common comorbid condition in CHF patients, and the lack of proper treatment could be associated with an increased risk of death.8 In this sense, MAD has been shown to reduce OSA-induced hypoxemia, reduce the severity of the OSA, and increase oxygen saturation in CHF patients.
By keeping the upper airways clear, MAD reduces negative intrathoracic pressure. Therefore, treating the OSA with MAD in CHF patients is beneficial and, similar to CPAP, will reduce cardiac stress and circulating BNP levels.
In a similar study, Liu et al.8 observed that the left ventricle's systolic and diastolic function improved significantly with a MAD. According to the authors, the beneficial effects of a MAD by increasing the upper airway dimensions would enhance the oxygen saturation in the blood and avoid the elevation of intrathoracic pressure.
Ferreira et al.5 analyzed the prevalence of apnea in 103 patients with a history of heart failure and found that 72.8% had moderate to severe obstructive apnea. In addition, most of the obstructive apnea patients were overweight men.
More than half a sample had left ventricular systolic dysfunction, which is more prevalent in patients with obstructive apnea whose pulmonary arterial pressure values were higher, with more fragmented sleep and nocturnal desaturation. In addition, the left atrium diameter was an obstructive apnea predictive factor (with every millimeter, the risk increased).
The authors considered it necessary to screen all patients with a history of cardiac pathology for apnea. Although they did not find risk factors for obstructive apnea in patients with previous heart failure, they did conclude that male gender, enlarged neck, severe systolic dysfunction, left ventricular hypertrophy, and left ventricular and left atrium enlargement were factors significantly associated with the presence of obstructive apnea.
Recently, Liu et al.8 conducted a study on rabbits in which they analyzed the effect of the MAD treatment on cardiovascular complications in OSA patients. Through echocardiography, they determined the structure and function of the heart.
According to the authors, the chronic intermittent hypoxia typical of the OSA appears to induce the sympathetic nervous system overactivity, causing overproduction of angiotensin II, a peptide that regulates vascular tone and blood pressure, as well as an increase in endothelin-1, a vasoconstrictor secreted by the endothelium that has an essential role in the pathogenesis of cardiovascular disorders.
Therefore, OSA-induced myocardial lesions are associated with the overproduction of these systemic cytokines due to hypoxia. OSA-induced cardiac dysfunction was prevented by a MAD treatment: the basement membrane thickened slightly, suggesting that the capillary ultrastructure between myocardial fibers improved with the MAD therapy.
These results suggest that the myocardial injury associated with the OSA can be rescued through a MAD. Furthermore, the hypoxia produced by the OSA was associated with elevated systemic cytokines, which could cause myocardial damage.
Based on the literature reviewed, scientific evidence supports the benefit of using a MAD in patients with previous cardiac disease.
CONCLUSIONS
According to the evidence reviewed, preventing cardiac complications in OSA patients is related to preventing respiratory events. Therefore, a MAD is recommended, even in severe cases, although more clinical studies are necessary.
REFERENCES
AFFILIATIONS
1 Práctica privada en Medicina Dental del Sueño. Ciudad de México, México. Universidad Católica San Antonio. Murcia, España.
2 Máster en Medicina Dental del Sueño. Universidad Católica San Antonio. Murcia, España.
CORRESPONDENCE
Juan Manuel Cortés-Mejía. E-mail: juan_manuel_cortez@hotmail.comReceived: Mayo 2020. Accepted: Agosto 2020.