Echocardiographic features of the right heart in sleep-disordered breathing: the Framingham Heart Study

Correlation between obstructive sleep apnea and ventricular function: a cross-sectional hospital-based study

BACKGROUND

Obstructive sleep apnoea (OSA) is a major cause of cardiovascular morbidity and mortality worldwide. Previous studies showed high prevalence of OSA in heart failure. We aimed to evaluate the association of OSA with cardiac dysfunction and the importance of myocardial performance index (Tei) in identifying cardiac dysfunction.

METHODS

Participants with OSA and sinus rhythm were included, while participants with arrhythmia, debilitating disease, or significant valvular heart disease were excluded. Thirty participants were enrolled, consecutively allocated in a single group, and underwent nocturnal polysomnography, electrocardiogram, and transthoracic echocardiography.

RESULTS

The prevalence of hypertension, diabetes, and smoking in the study population was 50%, 30%, and 23.3%, respectively. The mean body mass index and apnoea-hypopnoea index (AHI) of the study population was 40.11 ± 7.5 kg/m2 and22.12 ± 13.54 events/h, respectively. There were statistically significant differences between mild, moderate, and severe OSA regarding the left ventricular end diastolic diameter, left ventricular end systolic diameter, ejection fraction, and fractional shortening (p = 0.006, p = 0.002, p = 0.014 and p = 0.011),respectively. There were statistically significant regular positive correlations between the AHI and the right and left Tei (r = 0.447, p = 0.001 and r = 0.391, p = 0.003),respectively.

CONCLUSIONS

The prevalence of OSA was more in patients with comorbidities especially hypertension and diabetes. OSA was significantly associated with ventricular remodelling and cardiac dysfunction. A significant regular positive correlation was observed between the severity of OSA and worsening cardiac function as measured by Tei. Echocardiographic evaluation of the right and left ventricles and the right and left Tei could be considered as potentially valid, reproducible, and clinically applicable non-invasive methods for estimation of ventricular global function in patients with OSA.

Inflamed adipose tissue: A culprit underlying obesity and heart failure with preserved ejection fraction

The incidence of heart failure with preserved ejection fraction is increasing in patients with obesity, diabetes, hypertension, and in the aging population. However, there is a lack of adequate clinical treatment. Patients with obesity-related heart failure with preserved ejection fraction display unique pathophysiological and phenotypic characteristics, suggesting that obesity could be one of its specific phenotypes. There has been an increasing recognition that overnutrition in obesity causes adipose tissue expansion and local and systemic inflammation, which consequently exacerbates cardiac remodeling and leads to the development of obese heart failure with preserved ejection fraction. Furthermore, overnutrition leads to cellular metabolic reprogramming and activates inflammatory signaling cascades in various cardiac cells, thereby promoting maladaptive cardiac remodeling. Growing evidence indicates that the innate immune response pathway from the NLRP3 inflammasome, to interleukin-1 to interleukin-6, is involved in the generation of obesity-related systemic inflammation and heart failure with preserved ejection fraction. This review established the existence of obese heart failure with preserved ejection fraction based on structural and functional changes, elaborated the inflammation mechanisms of obese heart failure with preserved ejection fraction, proposed that NLRP3 inflammasome activation may play an important role in adiposity-induced inflammation, and summarized the potential therapeutic approaches.

The Effect of Gender and Sex Hormones on Cardiovascular Disease, Heart Failure, Diabetes, and Atrial Fibrillation in Sleep Apnea

Sleep apnea is a highly prevalent disorder with increasing impact on healthcare systems worldwide. Previous studies have been conducted primarily with male subjects, and prevalence and severity of sleep apnea in women are underestimated. Recent clinical and basic science evidence increasingly points to different mechanisms in men and women with sleep-disordered breathing (SDB). SDB is associated with a variety of comorbidities, including cardiovascular disease, heart failure, diabetes, and atrial fibrillation. In this review, we discuss sex-dependent mechanisms of SDB in select associated conditions to sharpen our clinical understanding of these sex-dependent inherent differences.

Obstructive sleep apnoea syndrome and left ventricular hypertrophy: a meta-analysis of echocardiographic studies

AIM

We investigated the association between obstructive sleep apnoea (OSA) and subclinical cardiac organ damage through a meta-analysis of echocardiographic studies that provided data on left ventricular hypertrophy (LVH), assessed as a categorical or continuous variable.

DESIGN

The PubMed, OVID-MEDLINE, and Cochrane library databases were systematically analyzed to search English-language articles published from 1 January 2000 to 15 August 2019. Studies were detected by using the following terms: 'obstructive sleep apnea', 'sleep quality', 'sleep disordered breathing', 'cardiac damage', 'left ventricular mass', 'left ventricular hypertrophy', and 'echocardiography'.

RESULTS

Meta-analysis included 5550 patients with OSA and 2329 non-OSA controls from 39 studies. The prevalence of LVH in the pooled OSA population was 45% (CI 35--55%). Meta-analysis of studies comparing the prevalence of LVH in participants with OSA and controls showed that OSA was associated with an increased risk of LVH (OR = 1.70, CI 1.44-2.00, P < 0.001). LV mass was significantly increased in patients with severe OSA as compared with controls (SMD 0.46 ± 0.08, CI 0.29-0.62, P < 0.001) or with mild OSA. This was not the case for studies comparing patients with unselected or predominantly mild OSA and controls (0.33 ± 0.17, CI -0.01 to 0.67, P = 0.057).

CONCLUSION

The present meta-analysis expands previous information on the relationship between OSA and echocardiographic LVH, so far based on individual studies. The overall evidence strongly suggests that the likelihood of LVH increases with the severity of OSA, thus exhibiting a continuous relationship.

Obesity cardiomyopathy: evidence, mechanisms, and therapeutic implications

The prevalence of heart failure is on the rise and imposes a major health threat, in part, due to the rapidly increased prevalence of overweight and obesity. To this point, epidemiological, clinical, and experimental evidence supports the existence of a unique disease entity termed “obesity cardiomyopathy,” which develops independent of hypertension, coronary heart disease, and other heart diseases. Our contemporary review evaluates the evidence for this pathological condition, examines putative responsible mechanisms, and discusses therapeutic options for this disorder. Clinical findings have consolidated the presence of left ventricular dysfunction in obesity. Experimental investigations have uncovered pathophysiological changes in myocardial structure and function in genetically predisposed and diet-induced obesity. Indeed, contemporary evidence consolidates a wide array of cellular and molecular mechanisms underlying the etiology of obesity cardiomyopathy including adipose tissue dysfunction, systemic inflammation, metabolic disturbances (insulin resistance, abnormal glucose transport, spillover of free fatty acids, lipotoxicity, and amino acid derangement), altered intracellular especially mitochondrial Ca²⁺ homeostasis, oxidative stress, autophagy/mitophagy defect, myocardial fibrosis, dampened coronary flow reserve, coronary microvascular disease (microangiopathy), and endothelial impairment. Given the important role of obesity in the increased risk of heart failure, especially that with preserved systolic function and the recent rises in COVID-19-associated cardiovascular mortality, this review should provide compelling evidence for the presence of obesity cardiomyopathy, independent of various comorbid conditions, underlying mechanisms, and offer new insights into potential therapeutic approaches (pharmacological and lifestyle modification) for the clinical management of obesity cardiomyopathy.

Evaluation of right ventricular performance and impact of continuous positive airway pressure therapy in patients with obstructive sleep apnea living at high altitude

Obstructive sleep apnea syndrome (OSAS) can lead to alterations in right ventricular (RV) performance and pulmonary vascular haemodynamics. Additionally, altitude-related hypoxia is associated with pulmonary vasoconstriction, and the effect of high-altitude on the pulmonary circulation in OSAS patients can be further altered. We sought to assess alterations in RV morphology and function in OSAS patients living at high altitude by way of 2-dimensional speckle tracking echocardiography (2D-STE), real-time 3- dimensional echocardiography (RT-3DE) and cardiac biomarkers. We also evaluate the impact of continuous positive airway pressure (CPAP) treatment on RV performance. Seventy-one patients with newly diagnosed OSAS and thirty-one controls were included in this study. All individuals were assessed for cardiac biomarkers as well as underwent 2D-STE and RT-3DE. Forty-five OSAS patients underwent CPAP therapy for at least 24 weeks and were studied before and after CPAP treatment. RT-3DE was used to measure RV volume, and calculate RV 3D ejection fraction (3D RVEF). Peak systolic strain was determined. Cardiac biomarkers, including C-reactive protein (CRP), N-terminal pro-B-type natriuretic peptide, and cardiac troponin T were also measured. Right atrium volume index, RV volume, RV volume index, systolic pulmonary artery pressure (sPAP), pulmonary vascular resistance (PVR) and level of serum CRP were significantly higher in OSAS group, while OSAS patients showed lower 3D RVEF and RV longitudinal strains. Compared to the patients with sPAP < 40 mmHg, RV longitudinal strains in patients with sPAP ≥ 40 mmHg were lower. Both RV global longitudinal strain and sPAP were associated with apnea–hypopnea index. Patients treated with 6 months of CPAP therapy had significant improvement in RV geometry and performance. RV structural abnormalities and RV function impairments were observed in OSAS patients living at moderate high altitude compared to control highlanders. The reversibility of these changes after application of CPAP were further confirmed.

Effect of long term CPAP therapy on cardiac parameters assessed with cardiac MRI

The obstructive sleep apnoea syndrome (OSAS) is a disorder with a high prevalence and is associated with an elevated cardiovascular risk and increased morbidity and mortality. For longitudinal studies and functional analysis cardiac MRI is regarded as the gold standard. Aim of this study was to evaluate the long-term effect of continuous positive airway pressure (CPAP) therapy on cardiac functional parameters with cardiac Magnetic Resonance Imaging (cMRI). 54 patients with OSAS (mean apnea hypopnea index-AHI: 31) were prospectively enrolled in this study and cMRI was performed before and after 7 months of CPAP therapy. Data were acquired on a 1.5 T MRI and right and left ventricular cardiac function were analysed. CPAP treatment was considered compliant when used ≥ 4 h per night. 24-h blood pressure was measured at baseline and follow up. 33 patients could be assigned to the compliance group. Left ventricular stroke volume (LV SV) and right ventricular ejection fraction (RV EF) improved significantly with CPAP therapy (LV SV from 93 ± 19 to 99 ± 20 ml, p = 0.02; RV EF from 50 ± 6 to 52 ± 6%, p = 0.04). All other cardiac parameters did not change significantly while mean systolic and diastolic blood pressure improved significantly (p < 0.01). 21 patients were assigned to the non-compliance group and were considered as a control group. There were no relevant differences in cardiac parameters between baseline and follow up examination in these patients. CPAP therapy seems to improve LV SV, RV EF, systolic and diastolic blood pressure in OSAS patients, but reproducibility of our results need to be confirmed in a larger patient population.

A Case of Right Ventricular Dysfunction with Right Ventricular Failure Secondary to Obesity Hypoventilation Syndrome

Patient: Male, 53

Final Diagnosis: Right ventricular dysfunction secondary to obesity hypoventilation syndrome

Symptoms: Shortness of breath

Medication: —

Clinical Procedure: Echocardiogram (TTE)

Specialty: Cardiology

The epidemiology of obstructive sleep apnoea and cardiovascular disease

Obstructive sleep apnoea, the most common form of sleep-disordered breathing, is highly prevalent in patients with cardiovascular disease. The last 30 years has seen a plethora of large scale epidemiological studies investigating the relationship between sleep apnoea and cardiovascular outcomes. This review highlights the key epidemiological studies addressing the links between sleep apnoea and hypertension, cardiac arrhythmias, cerebrovascular disease, coronary artery disease, heart failure and pulmonary hypertension, with a particular focus on some of the most recent reports.

Review of Echocardiographic Findings in Patients with Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) causes recurrent apneas due to upper respiratory tract collapse, leading to sympathetic nervous system hyperactivation and increased cardiovascular risk. Moderate and severe forms of obstructive sleep apnea are associated with increased atrial volumes and affect left ventricular diastolic and then systolic function. Right ventricular ejection fraction can be accurately assessed via three-dimensional echocardiography, while bidimensional imaging can only provide a set of surrogate parameters to characterize systolic function (tricuspid annulus plane systolic excursion, right ventricular fractional area change, and lateral S'). Tissue Doppler imaging is a more sensitive tool in detecting functional ventricular impairment, but its use is limited by angle dependence and the unwanted influence of tethering forces. Two-dimensional speckle tracking echocardiography is considered more suitable for the assessment of ventricular function, as it is able to distinguish between active and passive wall motion. Abnormal strain values, a marker of subclinical myocardial dysfunction, can be detected even in patients with normal ejection fraction and chamber volumes. The left ventricular longitudinal strain is more affected by the presence of obstructive sleep apnea than circumferential strain values. Although the observed OSA-induced changes are subtle, the benefit of a detailed echocardiographic screening for subclinical heart failure in OSA patients on therapy adherence and outcome should be addressed by further studies.

Obstructive sleep apnea in patients with chronic thromboembolic pulmonary hypertension

Background

Due to its effects, like an exaggerated negative intrathoracic pressure, sympathetic activation, systemic inflammation, oxidative stress, and endothelial dysfunction, obstructive sleep apnea (OSA) has been involved as a cause in multiple cardiovascular diseases. These diseases include coronary artery disease, hypertension, heart failure, and pulmonary hypertension (PH). Furthermore, OSA often coexists with chronic thromboembolic pulmonary hypertension (CTEPH) in clinical practice. However, few studies focus on OSA and its relationship with CTEPH. This study aims to determine whether OSA has an influence on the clinic status of patients with CTEPH, and to identify what possible factors are associated with OSA in CTEPH.

Methods

Patients who were newly diagnosed with CTEPH and received overnight polysomnography (PSG) monitoring from September 2015 to December 2017 were enrolled. OSA was defined as apnea-hypopnea index (AHI) of ≥5/h and the obstructive events at ≥50%. Baseline clinical characteristics and parameters were collected and compared between CTEPH patients with and without OSA. In addition, logistic regression analysis was performed to identify possible factors associated with OSA in CTEPH.

Results

Fifty-seven patients with CTEPH were eventually enrolled. Among them, 32 patients were diagnosed with OSA by PSG. CTEPH patients with OSA showed an older age, a higher body mass index (BMI), a higher hemoglobin level, a lower oxygen saturation and a worse World Health Organization functional class (WHO FC) (all P<0.05) when compared to CTEPH patients without OSA. In addition, sleep data including AHI, oxygen desaturation index and minimum oxygen saturation were also statistically different between two groups (all P<0.05). Adjusted for age, sex and BMI, hemoglobin [odd ratio (OR) =1.057, 95% confidence interval (CI): 1.001-1.117, P=0.046], oxygen saturation (OR =0.718, 95% CI: 0.554-0.929, P=0.012), N-terminal pro-brain natriuretic peptide (OR =1.001, 95% CI: 1.000-1.002, P=0.016), mean right atrium pressure (OR =1.284, 95% CI: 1.030-1.600, P=0.026), mean pulmonary arterial pressure (mPAP) (OR =1.087, 95% CI: 1.001-1.180, P=0.048), cardiac index (CI) (OR =0.058, 95% CI: 0.008-0.433, P=0.037), pulmonary vascular resistance (OR =1.004, 95% CI: 1.001-1.007, P=0.014) and WHO FC III-IV (OR =18.550, 95% CI: 2.363-144.128, P=0.005) were associated with OSA in CTEPH. Multivariate logistic regression analysis demonstrated CI (OR =0.051, 95% CI: 0.003-0.868, P=0.040) was independently associated with OSA in CTEPH in addition to age, sex and BMI.

Conclusions

OSA may aggravate the clinical status of CTEPH patients to some degree. In turn, a worse hemodynamics, oxygenation state and cardiac function are associated with OSA in CTEPH after being adjusted for age, sex and BMI. Among them, CI is the most important parameter in indicating the coexistence of OSA and CTEPH.

Chronological Change of Right Ventricle by Chronic Intermittent Hypoxia in Mice

Study Objective

No studies have investigated sequential changes in the heart on magnetic resonance imaging (MRI), along with observation of functional lung phenotypes and genetics, over the duration of chronic intermittent hypoxia (CIH). We investigated chronological changes in heart and lung phenotypes after CIH using a mouse model to provide new insights into the pathophysiology of sleep apnea-induced cardiovascular disease.

Methods

C57BL/6J adult male mice were randomized to 4 or 8 weeks of CIH. Cardiac cine-MRI images were analyzed to assess functional parameters of right ventricle (RV). Histopathological features of myocytes and pulmonary vessels, as well as genes involved in the endothelin (ET) system, were investigated.

Results

Function of the RV reduced significantly at 4 weeks and continuously decreased following another 4 weeks of CIH, although the rate of decrease was attenuated. Notably, persistence of reduced ejection fraction and end-systole RV wall thickness (WT) and increases in the ET system of the lungs and blood strongly implied the development of pulmonary hypertension after 8 weeks of CIH.

Conclusions

RV dysfunction with reduced end-systole RV WT could be a late phenotype in long-standing CIH and possibly also in obstructive sleep apnea.

Right Ventricular Remodeling and Dysfunction in Obstructive Sleep Apnea: A Systematic Review of the Literature and Meta-Analysis

Background

Recent studies have reported that obstructive sleep apnea (OSA) patients present alterations in right ventricular (RV) structure and function. However, large randomized controlled trials evaluating the impact of OSA on the right ventricle are lacking.

Methods

A comprehensive electronic database (PubMed, Web of Science, and Google Scholar) and reference search up to October 30, 2016, was performed. A systematic review and meta-analysis were performed to assess RV structure and function in OSA patients based on conventional echocardiography and tissue Doppler imaging.

Results

Twenty-five studies with 1,503 OSA patients and 796 controls were included in this study. OSA patients exhibited an increase in RV internal diameter (weighted mean difference (WMD) (95% confidence intervals (CIs)) 2.49 (1.62 to 3.37); p = 0.000) and RV wall thickness (WMD (95% CIs) 0.82 (0.51 to 1.13); p = 0.000). Furthermore, OSA patients had a significantly elevated RV myocardial performance index (WMD (95% CI) 0.08 (0.06 to 0.10); p = 0.000), decreased RV S' (WMD (95% CI) −0.95 (−1.59 to −0.32); p = 0.003), tricuspid annular plane systolic excursion (WMD (95% CI) −1.76 (−2.73 to −0.78); p = 0.000), and RV fractional area change (WMD (95% CI) −3.16 (−5.60 to −0.73); p = 0.011).

Conclusion

OSA patients display RV dilatation, increased wall thickening, and altered RV function.

Sleep-disordered breathing and daytime cardiac conduction abnormalities on 12-lead electrocardiogram in community-dwelling older men

PURPOSE

Nocturnal cardiac conduction abnormalities are commonly observed in patients with sleep-disordered breathing (SDB). However, few population-based studies have examined the association between SDB and daytime cardiac conduction abnormalities.

METHODS

We examined a random sample of 471 community-dwelling men, aged ≥67 years, enrolled in the multi-center Outcomes of Sleep Disorders in Older Men (MrOS Sleep) study. SDB severity was categorized using percent of total sleep time with oxygen saturation <90 % (%TST < 90) and apnea hypopnea index (AHI). Cardiac conduction parameters were assessed by resting 12-lead electrocardiography (ECG). All analyses were adjusted for age, site, β-blocker use, coronary heart disease, calcium channel blocker use, and use of antiarrhythmic medications.

RESULTS

Mean age was 77 ± 6 years, median %TST < 90 was 0.7 (IQR 0.00-3.40), and median AHI was 7.06 (IQR 2.55-15.32). Men with greater nocturnal hypoxemia (%TST < 90 ≥ 3.5 %) compared with those without hypoxemia (%TST < 90 < 1.0 %) had a lower odds of bradycardia (OR 0.55 [0.32-0.94]) and right bundle branch block (RBBB) (OR 0.24 [0.08-0.75]) but a higher odds of ventricular paced rhythm (OR 4.42 [1.29-15.19]). Heart rate (HR) increased in a graded manner with increasing %TST < 90 (p-trend 0.01) and increasing AHI (p-trend 0.006), but these gradients were small in absolute magnitude. There were no associations of SDB measures with other ECG conduction parameters.

CONCLUSIONS

Greater nocturnal hypoxemia in older men was associated with a lower prevalence of daytime sinus bradycardia and RBBB, a higher prevalence of ventricular paced rhythm, and higher resting HR.

Relation Between Obesity, Metabolic Syndrome, Successful Long-Term Weight Reduction, and Right Ventricular Function

This study sought to examine the relationships between right ventricular (RV) function and geometry, morbid obesity with and without the metabolic syndrome, and the effect of long-term weight loss. Obese (n = 153, BMI 41.2 ± 8.7 kg/m(2)) and healthy non-obese control subjects (n = 38, BMI 25.5 ± 3.3 kg/m(2)) of similar age and gender distribution were prospectively studied during the course of a 1-year weight reduction program with echocardiography at baseline and after one year of follow up. Function and geometry of the right heart were evaluated by tricuspid annular plane systolic excursion (TAPSE), tricuspid annular systolic velocity (TDI S'), RV myocardial performance index (TEI), RV end-diastolic (RVEDD) and end-systolic diameter (RVESD), area of the right atrium (RAA), and systolic pulmonary artery pressure (PAP). Whereas parameters of systolic and diastolic LV function were significantly worse in the obese subjects than those in the non-obese subjects (EF 66 ± 6 versus 69 ± 6%, P = 0.004; E/E' 7.4 ± 2.5 versus 6.3 ± 2.6, P = 0.010), parameters of RV function (TAPSE 25.6 ± 4.5 versus 25.1 ± 3.5 mm, P = 0.528; TDI S' 13.5 ± 2.9 versus 13.8 ± 2.9 mm/second, P = 0.553; TEI 0.25 ± 0.13 versus 0.28 ± 0.09, P = 0.283) as well as geometry measurements were comparable between the obese and non-obese participants and also in obese subjects with full blown metabolic syndrome. Additionally, successful weight reduction did not alter the RV parameters. Nevertheless, in the few obese subjects with RV dysfunction (n = 7), metabolic syndrome parameters were more pronounced than in obese with normal RV function.Morbid obesity with and without the metabolic syndrome is accompanied by an impaired LV systolic and diastolic function. In contrast, RV function appears to be less affected by obesity independent of the presence of the metabolic syndrome.

Biventricular Myocardial Performance Is Impaired in Proportion to Severity of Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is an independent risk factor for cardiovascular morbidity and death. Little information is available regarding the relationship between the severity of OSA and myocardial performance in OSA patients who have normal ejection fractions. We prospectively investigated this relationship, using the tissue-Doppler myocardial performance index (TD-MPI). We conducted overnight, full-laboratory polysomnographic examinations of 116 patients, and calculated the left and right ventricular TD-MPIs. Patients were classified into 3 groups in accordance with their apnea-hypopnea index (AHI) levels: AHImild (≥5 to <15), AHImoderate (≥15 to <30), and AHIsevere (≥30). Left and right ventricular TD-MPI values were higher in the AHIsevere group than in the AHImild and AHImoderate groups (all P <0.05). In addition, right ventricular TD-MPI values in the AHImoderate group were higher than those in the AHImild group (P <0.05). Right ventricular TD-MPI was significantly associated with AHI (β=0.468, P <0.001), left ventricular TD-MPI, and right ventricular early-to-late filling velocities (E/A ratio) in multiple linear regression analysis. On the other hand, left ventricular TD-MPI was significantly associated with right ventricular TD-MPI and left ventricular E/A ratio (both P <0.05). Our results show that OSA severity, determined by means of AHI, is independently associated with impaired right and left ventricular function as indicated by TD-MPI in patients who have OSA and normal ejection fractions.

A clinical approach to obstructive sleep apnea as a risk factor for cardiovascular disease

Obstructive sleep apnea (OSA) is associated with cardiovascular risk factors, cardiovascular diseases, and increased mortality. Epidemiological studies have established these associations, and there are now numerous experimental and clinical studies which have provided information on the possible underlying mechanisms. Mechanistic proof-of-concept studies with surrogate endpoints have been performed to demonstrate that treatment of OSA by continuous positive airway pressure (CPAP) has the potential to reverse or at least to attenuate not only OSA but also the adverse cardiovascular effects associated with OSA. However, no randomized studies have been performed to demonstrate that treatment of OSA by CPAP improves clinical outcomes in patients with cardiovascular risk factors and/or established cardiovascular disease and concomitant OSA. In the present review, we summarize the current knowledge on the role of OSA as a potential cardiovascular risk factor, the impact of OSA on cardiac function, the role of OSA as a modifier of the course of cardiovascular diseases such as coronary artery disease, atrial fibrillation, and heart failure, and the insights from studies evaluating the impact of CPAP therapy on the cardiovascular features associated with OSA.

Usefulness of Low Cardiac Index to Predict Sleep-Disordered Breathing in Chronic Thromboembolic Pulmonary Hypertension

Patients with chronic thromboembolic pulmonary hypertension (CTEPH) often have substantial right ventricular dysfunction. The resulting low cardiac index might predispose to sleep disordered breathing (SDB) by increasing ventilatory instability. The prevalence of SDB and potential association with impaired cardiac index was examined in patients with CTEPH. Patients referred for evaluation for pulmonary thromboendarterectomy surgery were recruited. Subjects underwent a sleep study, unless already using positive airway pressure therapy. Hemodynamic data were obtained from contemporaneous right-sided cardiac catheterization. A total of 49 subjects were included. SDB-defined as ongoing positive airway pressure use or apnea-hypopnea index (AHI) ≥5/h-was found in 57% of subjects. SDB was generally mild in severity, with respiratory events mainly consisting of hypopneas. Cardiac index was found to be significantly lower in subjects with SDB than those without (2.19 vs 2.55 L/min/m(2); p = 0.024), whereas no differences were observed in other characteristics. Additionally, cardiac index was independently predictive of AHI. In a subgroup of subjects with an elevated percentage of central events, both cardiac index and lung to finger circulation time correlated with AHI. In conclusion, SDB is prevalent in patients with CTEPH and might decrease with treatments that improve cardiac index.

Sleep Disordered Breathing: Hypertension and Cardiac Structure and Function

Obstructive sleep apnea (OSA) is a common form of sleep disordered breathing and has a relatively high prevalence in the general population. The frequency and severity of OSA is associated with age, male sex, and obesity, and OSA has been linked to cardiovascular complications and death. Importantly, OSA has a strong association with both prevalent and incidental hypertension and has a particularly high prevalence in patients with resistant hypertension. In these patients, CPAP and other OSA-directed treatments have been proposed as therapy to help control blood pressure (BP), especially in patients who have not attained optimal BP control despite maximum pharmacological therapy. OSA has also been associated with alterations in cardiac structure and function, although most studies are small and highly limited in study design. Existing data suggest an association between OSA greater left ventricle (LV) mass and hypertrophy that appears independent of confounders including hypertension and obesity. Although less clear and more controversial, OSA severity has been linked to LV systolic and diastolic function, pulmonary hypertension, and right ventricular hypertrophy. Further studies are needed to confirm the potential causal role of OSA in these observed associations with cardiac abnormalities.

Prevalence of obstructive sleep apnea among patients with coronary artery disease in Saudi Arabia

BACKGROUND

Despite the association between obstructive sleep apnea (OSA) and coronary artery disease (CAD), few studies have investigated this issue in Saudi Arabia.

OBJECTIVES

This study aimed to identify the prevalence of OSA among CAD patients.

SUBJECTS AND METHODS

This was a cross-sectional (descriptive) study conducted at King Abdul-Aziz University Hospital in Jeddah, Saudi Arabia from April 2012 to December 2013. All consecutive patients referred to the cardiac catheterization lab for coronary angiography who exhibited evidence of CAD were included in this study. This study was conducted in two stages. During the first stage, each participant was interviewed individually. The administered interview collected data pertaining to demographics, comorbidities, and the STOP-BANG questionnaire score. The second stage of this study consisted of a diagnostic overnight polysomnography (PSG) of 50% of the subjects at high risk for OSA according to the STOP-BANG questionnaire.

RESULTS

Among the patients with CAD (N = 156), 128 (82%) were categorized as high risk for developing OSA. PSG was conducted on 48 patients. The estimated prevalence of OSA in the study sample was 56.4%. Approximately 61% of the documented sleep apnea patients suffered from moderate to severe OSA.

CONCLUSION

This local study concurs with reports in the literature indicating that OSA is very common among CAD patients.

Development of the National Healthy Sleep Awareness Project Sleep Health Surveillance Questions

OBJECTIVES

For the first time ever, as emphasized by inclusion in the Healthy People 2020 goals, sleep health is an emphasis of national health aims. The National Healthy Sleep Awareness Project (NHSAP) was tasked to propose questions for inclusion in the next Behavioral Risk Factor Surveillance System (BRFSS), a survey that includes a number of questions that target behaviors thought to impact health, as a means to measure community sleep health. The total number of questions could not exceed five, and had to include an assessment of the risk for obstructive sleep apnea (OSA).

METHODS

An appointed workgroup met via teleconference and face-to-face venues to develop an inventory of published survey questions being used to identify sleep health, to develop a framework on which to analyze the strengths and weaknesses of current survey questions concerning sleep, and to develop recommendations for sleep health and disease surveillance questions going forward.

RESULTS

The recommendation was to focus on certain existing BRFSS questions pertaining to sleep duration, quality, satisfaction, daytime alertness, and to add to these other BRFSS existing questions to make a modified STOP-BANG questionnaire (minus the N for neck circumference) to assess for risk of OSA.

CONCLUSIONS

Sleep health is an important dimension of health that has previously received less attention in national health surveys. We believe that 5 questions recommended for the upcoming BRFSS question banks will assist as important measures of sleep health, and may help to evaluate the effectiveness of interventions to improve sleep health in our nation.

Sex-Specific Association of Sleep Apnea Severity With Subclinical Myocardial Injury, Ventricular Hypertrophy, and Heart Failure Risk in a Community-Dwelling Cohort: The Atherosclerosis Risk in Communities-Sleep Heart Health Study

BACKGROUND

Risk factors for obstructive sleep apnea (OSA) and the development of subsequent cardiovascular (CV) complications differ by sex. We hypothesize that the relationship between OSA and high-sensitivity troponin T (hs-TnT), cardiac structure, and CV outcomes differs by sex.

METHODS AND RESULTS

Seven hundred fifty-two men and 893 women free of CV disease participating in both the Atherosclerosis Risk in the Communities and the Sleep Heart Health Studies were included. All participants (mean age, 62.5 ± 5.5 years) underwent polysomnography and measurement of hs-TnT. OSA severity was defined by using established clinical categories. Subjects were followed for 13.6 ± 3.2 years for incident coronary disease, heart failure, and CV and all-cause mortality. Surviving subjects underwent echocardiography after 15.2 ± 0.8 years. OSA was independently associated with hs-TnT among women (P=0.03) but not in men (P=0.94). Similarly, OSA was associated with incident heart failure or death in women (P=0.01) but not men (P=0.10). This association was no longer significant after adjusting for hs-TnT (P=0.09). Among surviving participants without an incident CV event, OSA assessed in midlife was independently associated with higher left ventricle mass index only among women (P=0.001).

CONCLUSIONS

Sex-specific differences exist in the relationship between OSA and CV disease. OSA, assessed in midlife, is independently associated with higher levels of concomitantly measured hs-TnT among women but not men, in whom other comorbidities associated with OSA may play a more important role. During 13-year follow-up, OSA was associated with incident heart failure or death only among women, and, among those without an incident event, it was independently associated with left ventricular hypertrophy only in women.

Right ventricular geometry and mechanics in patients with obstructive sleep apnea living at high altitude

PURPOSE

Repetitive obstruction of larynx during sleep can lead to daytime pulmonary hypertension and alterations in right ventricular morphology and function in a small fraction of obstructive sleep apnea syndrome (OSAS) patients. Environmental effects, particularly high altitude, can modify the effects of OSAS on pulmonary circulation, since altitude-related hypoxia is related with pulmonary vasoconstriction. This potential interaction, however, was not investigated in previous studies.

METHODS

A total of 41 newly diagnosed OSAS patients were included in this study after pre-enrolment screening. Two-dimensional, three-dimensional, and Doppler echocardiographic data were collected after polysomnographic verification of OSAS. Three-dimensional echocardiograms were analyzed to calculate right ventricular volumes, volume indices, and ejection fraction.

RESULTS

Systolic pulmonary artery pressure (38.35 ± 8.60 vs. 30.94 ± 6.47 mmHg; p = 0.002), pulmonary acceleration time (118.36 ± 16.36 vs. 103.13 ± 18.42 ms; p = 0.001), right ventricle (RV) end-diastolic volume index (48.15 ± 11.48 vs. 41.48 ± 6.45 ml; p = 0.009), and RV end-systolic volume index (26.50 ± 8.11 vs. 22.15 ± 3.85; p = 0.01) were significantly higher in OSAS patients, with similar RV ejection fraction (EF) between groups. No significant differences were noted in other two-dimensional, Doppler or speckle-tracking strain, measurements. Both RVEF and pulmonary acceleration time were predictors of disease severity.

CONCLUSIONS

A greater degree of RV structural remodeling and higher systolic pulmonary pressure were observed in OSAS patients living at high altitude compared to healthy highlanders. The reversibility of these alterations with treatment remains to be studied.

Assessment of Right Ventricular Function in Obstructive Sleep Apnea Syndrome and Effects of Continuous Positive Airway Pressure Therapy: A Pilot Study

BACKGROUND

It is known that obstructive sleep apnea syndrome (OSAS) can affect right ventricular (RV) performance even in the absence of systemic hypertension and other known cardiac or obstructive pulmonary disease. The purpose of the present study was to assess RV function in OSAS using 3-D echocardiography and speckle tracking echocardiography (STE) and evaluate changes after continuous positive airway pressure (CPAP) treatment.

METHODS

Thirty-seven patients with OSAS without comorbidities and thirty control subjects were studied using 3-D echocardiography and STE. Fifteen patients underwent CPAP therapy and were studied before and after treatment. RV 3-D ejection fraction was calculated. Peak systolic strain was determined. RV dyssynchrony was defined as SD of the 6 time to peak systolic strain values.

RESULTS

3-D RV ejection fraction was lower and RV dyssynchrony was greater in patients with moderate-severe OSAS compared with control subjects in the presence and absence of pulmonary hypertension. 3-D RV ejection fraction and RV dyssynchrony were independently associated with apnea-hypopnea index. Patients treated with CPAP had significant changes in RV parameters.

CONCLUSIONS

3-D RV ejection fraction and RV dyssynchrony were abnormal in OSAS patients compared with control subjects and associated with OSAS severity. RV 3-D STE abnormalities improved after chronic application of CPAP.

Sleep apnea is associated with subclinical myocardial injury in the community. The ARIC-SHHS study

RATIONALE

Obstructive sleep apnea (OSA) is associated with cardiovascular morbidity and mortality, although the underlying mechanisms are not well understood.

OBJECTIVES

We aimed to determine whether more severe OSA, measured by the Respiratory Disturbance Index (RDI), is associated with subclinical myocardial injury and increased myocardial wall stress.

METHODS

A total of 1,645 participants (62.5 ± 5.5 yr and 54% women) free of coronary heart disease and heart failure and participating in both the Atherosclerosis Risk in the Communities and the Sleep Heart Health Studies underwent overnight polysomnography and measurement of high-sensitivity troponin T (hs-TnT) and N-terminal pro B-type natriuretic peptide (NT-proBNP).

MEASUREMENTS AND MAIN RESULTS

OSA severity was defined using conventional clinical categories: none (RDI ≤ 5), mild (RDI 5-15), moderate (RDI 15-30), and severe (RDI > 30). Hs-TnT, but not NT-proBNP, was associated with OSA after adjusting for 17 potential confounders (P = 0.02). Over a median of 12.4 (interquartile range, 11.6-13.1) years follow-up, hs-TnT was related to risk of death or incident heart failure in all OSA categories (P ≤ 0.05 in each category).

CONCLUSIONS

In middle-aged to older individuals, OSA severity is independently associated with higher levels of hs-TnT, suggesting that subclinical myocardial injury may play a role in the association between OSA and risk of heart failure. OSA was not associated with NT-proBNP levels after adjusting for multiple possible confounders.

Impact of untreated obstructive sleep apnea on left and right ventricular myocardial function and effects of CPAP therapy

Background

Obstructive sleep apnea (OSA) has deteriorating effect on LV function, whereas its impact on RV function is controversial. We aimed to determine the effect of OSA and continuous positive airway pressure (CPAP) treatment on left and right ventricular (LV, RV) function using transthoracic echocardiography (TTE) and 2 dimensional speckle tracking (2D ST) analysis of RV deformation capability.

Methods and Results

82 patients with OSA and need for CPAP therapy were prospectively enrolled and underwent TTE at study inclusion and after 6 months of follow up (FU). Multivariate regression analysis revealed an independent association between baseline apical right ventricular longitudinal strain (RV-Sl), BMI and the severity of OSA (apical RV-Sl: P = 0.0002, BMI: P = 0.02). After CPAP therapy, LV functional parameters (LVEF: P<0.0001, LV performance index: P = 0.03, stroke volume: P = 0.042), and apical RV-Sl (P = 0.001) improved significantly. The effect of CPAP therapy was related to severity of OSA (LVEF: AHI 5–14, 66.4±8.8%, 68.5±10.6% [P = ns]; AHI 15–30∶59.8±7.7%, 68.6±9.3% [P = 0.002]; AHI>30∶54.1±12.4%, 68.2±13.6%[P<0.0001]; apical RV-Sl: AHI 5–14: −17.3±8.7%, −16.0±10.8% [P = ns], AHI 15–30: −9.8±6.0%, −15.4±10.9% [P = 0.028], AHI>30: −6.3±5.7%, −17.9±11.2% [P<0.0001]).

Conclusions

OSA seems to have deteriorating effect on LV and RV function. We found a beneficial effect of CPAP on LV and RV functional parameters predominately in patients with severe OSA. 2D speckle tracking might be of value to determine early changes in global and regional right ventricular function.

Metabolic syndrome and right ventricle: an updated review

The cluster of metabolic and hemodynamic abnormalities which characterize the metabolic syndrome (MS) is responsible for subclinical cardiac and extra-cardiac damage such as left ventricular hypertrophy, diastolic dysfunction, carotid atherosclerosis and microalbuminuria. The development of different non-invasive imaging methods enabled a detail investigation of right ventricular structure and function, and revealed that right ventricular remodeling followed changes in the left ventricular structure and function in patients with arterial hypertension, diabetes or obesity. Previous investigations also reported that the coexistence of two components of the MS induced more significant cardiac remodeling than the presence of only one MS risk-factor. The relationship between different components of the MS (increased blood pressure, abdominal obesity, increased fasting glucose level and dyslipidemia) and right ventricular remodeling could be explained by several hemodynamic and non-hemodynamic mechanisms. However, the association between right ventricular remodeling and the MS has not been sufficiently investigated so far. The aim of this article was to review recent articles focusing on the association between metabolic syndrome components and the metabolic syndrome itself with impairments in right ventricular structure and function assessed by different imaging techniques.

The WHO classification of pulmonary hypertension: A case-based imaging compendium

Pulmonary hypertension (PH) is defined as a resting mean pulmonary artery pressure greater than 25 mmHg. The World Health Organization (WHO) classifies PH into five categories. The WHO nomenclature assumes shared histology and pathophysiology within categories and implies category-specific treatment. Imaging of the heart and pulmonary vasculature is critical to assigning a patient's PH syndrome to the correct WHO category and is also important in predicting outcomes. Imaging studies often reveal that the etiology of PH in a patient reflects contributions from several categories. Overlap between Categories 2 and 3 (left heart disease and lung disease) is particularly common, reflecting shared risk factors. Correct classification of PH patients requires the combination of standard imaging (chest roentgenograms, ventilation-perfusion scans, echocardiography, and the 12-lead electrocardiogram) and advanced imaging (computed tomography, cardiac magnetic resonance imaging, and positron emission tomography). Despite the value of imaging, cardiac catheterization remains the gold standard for quantification of hemodynamics and is required before initiation of PH-specific therapy. These cases illustrate the use of imaging in classifying patients into WHO PH Categories 1-5.

PFO and right-to-left shunting in patients with obstructive sleep apnea

BACKGROUND

Patent foramen ovale (PFO) with right-to-left shunt has a prevalence of 10% to 34% in the general population. It can cause an ischemic stroke, transient ischemic attack, and paradoxical peripheral or coronary embolization. Its influence on migraine and several other diseases and conditions is currently under debate. Attention has recently been turned to the correlation between PFO and obstructive sleep apnea. Thus far, studies on the prevalence of right-to-left shunts as a surrogate for PFO in these patients were limited by small sample sizes and the results have been conflicting. Here, we evaluate the prevalence of right-to-left shunting (RLS) through transcranial Doppler ultrasound (TCD) in a large patient group with obstructive sleep apnea (OSA).

METHODS

One hundred consecutive patients (mean age 59.5 y) with OSA underwent TCD with intravenous injection of agitated saline. The grading of right-to-left-shunts was in accordance with the Spencer PFO Grading Scale.

RESULTS

RLS was detected in 72 of 100 patients (72%). Thirty-four out of these 72 patients (47%) had a shunt grade I or II; 15 (21%) had a shunt Grade III or IV; and 23 (32%) had a large shunt (Grade V or V+). In 47 of 72 patients (65%), a right-to-left shunt was detectable at rest without Valsalva maneuver.

CONCLUSION

The prevalence of a RLS in patients with OSA is high. Provided other intracardiac or pulmonary shunts were absent, the high prevalence of a RLS suggests a high prevalence of PFO in patients with OSA.

Right ventricular dysfunction in chronic lung disease

Right ventricular (RV) dysfunction arises in chronic lung disease when chronic hypoxemia and disruption of pulmonary vascular beds increase ventricular afterload. RV dysfunction is defined by hypertrophy with preserved myocardial contractility and cardiac output. RV hypertrophy seems to be a common complication of chronic and advanced lung disease. RV failure is rare, except during acute exacerbations of chronic lung disease or when multiple comorbidities are present. Treatment is targeted at correcting hypoxia and improving pulmonary gas exchange and mechanics. There are no data supporting the use of pulmonary hypertension-specific therapies for patients with RV dysfunction secondary to chronic lung disease.

Obesity and pulmonary hypertension: a review of pathophysiologic mechanisms

Pulmonary hypertension (PH) is a potentially life-threatening condition arising from a wide variety of pathophysiologic mechanisms. Effective treatment requires a systematic diagnostic approach to identify all reversible mechanisms. Many of these mechanisms are relevant to those afflicted with obesity. The unique mechanisms of PH in the obese include obstructive sleep apnea, obesity hypoventilation syndrome, anorexigen use, cardiomyopathy of obesity, and pulmonary thromboembolic disease. Novel mechanisms of PH in the obese include endothelial dysfunction and hyperuricemia. A wide range of effective therapies exist to mitigate the disability of PH in the obese.

Echocardiographic findings in ischemic stroke patients with obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) has been associated with cardiac abnormalities. Whether any cardiac dysfunction is present in ischemic stroke patients with OSA is not known. The purpose of this study was to compare echocardiographic findings in ischemic stroke patients with and without OSA.

METHODS

Nocturnal polysomnography was performed on 28 ischemic stroke subjects within 7 days of symptom onset. OSA was defined as an apnea-hypopnea index of ≥10. Echocardiographic variables were compared between the OSA and non OSA groups using Wilcoxon signed-rank, chi-square, or Fisher's exact tests.

RESULTS

The 14 (50%) subjects with OSA had comparable cardiac function and structure to those without OSA (n=14). Left ventricular (LV) mass index, LV ejection fraction, LV diastolic function, left atrial area, and right ventricular systolic function were not different between groups. Ischemic stroke subjects, regardless of their OSA status, had LV diastolic dysfunction with preserved systolic function.

CONCLUSIONS

Subjects with and without OSA, based on polysomnography in the first 7 days after stroke, have comparable right and left ventricular function.

Intermittent hypoxia augments pulmonary vascular smooth muscle reactivity to NO: regulation by reactive oxygen species

Intermittent hypoxia (IH) resulting from sleep apnea can lead to pulmonary hypertension. IH causes oxidative stress that may limit bioavailability of the endothelium-derived vasodilator nitric oxide (NO) and thus contribute to this hypertensive response. We therefore hypothesized that increased vascular superoxide anion (O(2)(-)) generation reduces NO-dependent pulmonary vasodilation following IH. To test this hypothesis, we examined effects of the O(2)(-) scavenger tiron on vasodilatory responses to the endothelium-dependent vasodilator ionomycin and the NO donor S-nitroso-N-acetylpenicillamine in isolated lungs from hypocapnic-IH (H-IH; 3 min cycles of 5% O(2)/air flush, 7 h/day, 4 wk), eucapnic-IH (E-IH; cycles of 5% O(2), 5% CO(2)/air flush), and sham-treated (air/air cycled) rats. Next, we assessed effects of endogenous O(2)(-) on NO- and cGMP-dependent vasoreactivity and measured O(2)(-) levels using the fluorescent indicator dihydroethidium (DHE) in isolated, endothelium-disrupted small pulmonary arteries from each group. Both E-IH and H-IH augmented NO-dependent vasodilation; however, enhanced vascular smooth muscle (VSM) reactivity to NO following H-IH was masked by an effect of endogenous O(2)(-). Furthermore, H-IH and E-IH similarly increased VSM sensitivity to cGMP, but this response was independent of either O(2)(-) generation or altered arterial protein kinase G expression. Finally, both H-IH and E-IH increased arterial O(2)(-) levels, although this response was more pronounced following H-IH, and H-IH exposure resulted in greater protein tyrosine nitration indicative of increased NO scavenging by O(2)(-). We conclude that IH increases pulmonary VSM sensitivity to NO and cGMP. Furthermore, endogenous O(2)(-) limits NO-dependent vasodilation following H-IH through an apparent reduction in bioavailable NO.

The impact of body mass index on right ventricular systolic functions in normal and mildly obese healthy patients: a velocity vector imaging study

BACKGROUND

Increasing prevalence of obesity is a significant problem in Western countries. Obesity has many effects on cardiovascular structure, function, and hemodynamics. Our aim was to compare the impact of body mass index (BMI) on right ventricular (RV) functions among healthy subjects with conventional echocardiography, tissue Doppler imaging (TDI), and velocity vector imaging (VVI).

METHODS

Eighty-one healthy subjects divided into three group according to their BMI. All subjects were evaluated by conventional echocardiography, TDI, and VVI. A full polysomnogram were performed in subjects with BMI ≥ 30 km/m(2).

RESULTS

RV end-diastolic and end-systolic diameters of patients in these three groups were similar (P > 0.05). There were no differences between each group in RV outflow tract fractional shortening (P = 0.52) and tricuspid annular plane systolic excursion (P = 0.94). No correlation observed between BMI and RV systolic parameters obtained with TDI. Longitudinal peak systolic strain and SRs were similar in all groups through each segment (P > 0.05).

CONCLUSION

The results of our study show no changes in the RV functions in obese and overweight who were otherwise healthy subjects. We also revealed a significant correlation between BMI and left ventricular diameters and wall thickness but no relation with RV diameters or functions.

Cardiovascular consequences of sleep apnea

Cardiovascular disease has been the leading cause of death since 1900. Strategies for cardiovascular disease and prevention have helped to reduce the burden of disease, but it remains an important public health challenge. Therefore, understanding the underlying pathophysiology and developing novel therapeutic approaches for cardiovascular disease is of crucial importance. Recognizing the link between sleep and cardiovascular disease may represent one such novel approach. Obstructive sleep apnea (OSA), a common form of sleep-disordered breathing, has a high and rising prevalence in the general adult population, attributable in part to the emerging epidemic of obesity and enhanced awareness. OSA has been independently linked to specific cardiovascular outcomes such as hypertension, stroke, myocardial ischemia, arrhythmias, fatal and nonfatal cardiovascular events, and all-cause mortality. Treatment of OSA may represent a novel target to reduce cardiovascular health outcomes.

Obstructive sleep apnea: a cardiopulmonary perspective and medical therapeutics

The clinical importance of obstructive sleep apnea (OSA) is gradually rising to the extent that many clinicians now consider OSA as an underlying etiology or precipitating factor for many cardiovascular and pulmonary events. Although the incidence and pathophysiology underlying these cardiopulmonary structural and functional abnormalities are not well defined, various mechanisms are hypothesized. These include but are not limited to sympathetic activation, oxidative stress, inflammation, and endothelial dysfunction. Given the rising awareness of OSA, it is timely to review the effects of OSA on cardiovascular complications like arrhythmias and ventricular remodeling. In the later part of the review, we focused on the role of therapeutics in the management of patients with OSA. Although the role of medical therapeutics is not well defined, we reviewed the available literature focusing on the available options, supporting evidence and their role in specific subgroup of patients with OSA.

Obstructive sleep apnea and pulmonary hypertension

Obstructive sleep apnea (OSA) is associated with repetitive nocturnal arterial oxygen desaturation and hypercapnia, large intrathoracic negative pressure swings, and acute increases in pulmonary artery pressure. Rodents when exposed to brief, intermittent hypoxia for several hours per day to mimic OSA developed pulmonary vascular remodeling and sustained pulmonary hypertension and right ventricular hypertrophy within a few weeks. Until recently, however, it was unclear whether episodic nocturnal hypoxemia associated with OSA was sufficient to cause similar changes in humans. This controversy appears to have been resolved by several recent studies that have shown (a) pulmonary hypertension in 20% to 40% of patients with OSA in the absence of other known cardiopulmonary disorders and (b) reductions in pulmonary artery pressure in patients with OSA after nocturnal continuous positive airway pressure (CPAP) treatment. The pulmonary hypertension associated with OSA appears to be mild and may be due to a combination of precapillary and postcapillary factors including pulmonary arteriolar remodeling and hyperreactivity to hypoxia and left ventricular diastolic dysfunction and left atrial enlargement. Although measurable changes in the structure and function of the right ventricle have been reported in association with OSA, the clinical significance of these changes is uncertain. Right ventricular failure in OSA appears to be uncommon and is more likely if there is coexisting left-sided heart disease or chronic hypoxic respiratory disease.

The incremental effect of obstructive sleep apnea syndrome on right and left ventricular myocardial performance in newly diagnosed essential hypertensive subjects

Obstructive sleep apnea syndrome (OSAS) may predispose patients to congestive heart failure, suggesting a deleterious effect of OSAS on myocardial contractility. We investigated whether essential hypertensive individuals with OSAS are characterized by decreased right and left ventricular myocardial performance. Our study population consisted of 45 consecutive patients with newly diagnosed untreated stage I-II essential hypertension suffering from OSAS (35 men, aged 49+/-8 years) and 48 hypertensives without OSAS, matched for age, sex, level of blood pressure, heart rate, body mass index and smoking status. All subjects underwent polysomnography and echocardiography. Right and left ventricular functions were evaluated using the myocardial performance index (MPI). Right and left ventricular functions were altered in hypertensives with OSAS. The mean right MPI was 0.26+/-0.11 in hypertensives without OSAS and 0.51+/-0.16 in hypertensives with OSAS (P<0.01). The mean left MPI values were 0.29+/-0.07 and 0.44+/-0.13, respectively (P<0.01). Right and left MPI correlated positively and significantly with apnea-hypopnea index (rho=0.40, P=0.002).OSAS is associated with impaired right and left ventricular function. These phenomena were independent of hypertension.

Effects of continuous positive airway pressure therapy on right ventricular function assessment by tissue Doppler imaging in patients with obstructive sleep apnea syndrome

OBJECTIVES

The effects of continuous positive airway pressure (CPAP) therapy on right ventricular (RV) function in patients with obstructive sleep apnea syndrome (OSAS) has not been previously studied by tissue Doppler imaging (TDI). The aim of this study was to assess RV function using TDI in patients with OSAS before and after CPAP therapy.

METHODS

Twenty-eight patients with newly diagnosed OSAS in the absence of any confounding factors and 18 controls were included in this study. The peak systolic velocity (S'm), early (E'm) and late (A'm) diastolic myocardial peak velocities at tricuspid lateral annulus, isovolumic acceleration (IVA), myocardial precontraction time (PCT'm), myocardial contraction time (CT'm), and myocardial relaxation time (RT'm) were measured. All echocardiographic parameters were calculated 6 months after CPAP therapy.

RESULTS

The RV diastolic parameters such as E'm velocity and E'm-to-A'm ratio were significantly lower, RT'm was significantly prolonged, A'm velocity was similar in patients with OSAS compared to controls; and the RV systolic parameters such as IVA and CT'm were significantly lower and S'm was similar in patients with OSAS compared to controls. At the end of the treatment, 20 of 28 patients were compliant with CPAP therapy. E'm velocity, E'm-to-A'm ratio, IVA, and CT'm increased, PCT'm, PCT'm-to-CT'm ratio, and RT'm decreased significantly after therapy, whereas S'm velocity and A'm velocity did not change after CPAP treatment in the compliant patients.

CONCLUSION

OSAS is associated with RV systolic and diastolic dysfunction, and 6 months of CPAP therapy improves the RV systolic and diastolic dysfunction.

The Sleep Heart Health Study: a progress report

PURPOSE OF REVIEW

The Sleep Heart Health Study began in 1994 as a prospective cohort study of cardiovascular disease. The results of longitudinal analysis are not yet available, but numerous analyses of cross-sectional data have been published. This review provides an overview of study results so far.

RECENT FINDINGS

Recent findings covered in this review include a methodological study supporting the choice of a 4% oxyhemoglobin desaturation criterion for identification of hypopneas; evidence that sleepiness may modify the association of sleep apnea with hypertension; the association of sleep apnea with increased left ventricular mass in a pattern suggesting predominantly eccentric left ventricular hypertrophy; the association of restless legs syndrome with an increase in prevalent cardiovascular disease; and the results of a genome-wide association study of sleep and circadian phenotypes.

SUMMARY

Although designed as a prospective cohort study, analysis of cross-sectional data from the Sleep Heart Health Study has contributed numerous insights to the field of sleep medicine.