Morbid obesity influences the nocturnal electrocardiogram wave and interval durations among suspected sleep apnea patients

Background: Obesity is a global issue with a major impact on cardiovascular health. This study explores how obesity influences nocturnal cardiac electrophysiology in suspected obstructive sleep apnea (OSA) patients. Methods: We randomly selected 12 patients from each of the five World Health Organization body mass index (BMI) classifications groups (ntotal = 60) while keeping the group's age and sex matched. We evaluated 1965 nocturnal electrocardiography (ECG) samples (10 s) using modified lead II recorded during normal saturation conditions. R-wave peaks were detected and confirmed using dedicated software, with the exclusion of ventricular extrasystoles and artifacts. The duration of waves and intervals was manually marked. The average electric potential graphs were computed for each segment. Thresholds for abnormal ECG waveforms were P-wave > 120 ms, PQ interval > 200 ms, QRS complex > 120 ms for, and QTc > 440 ms. Results: Obesity was significantly (p <.05) associated with prolonged conduction times. Compared to the normal weight (18.5 ≤ BMI < 25) group, the morbidly obese patients (BMI ≥ 40) had a significantly longer P-wave duration (101.7 vs. 117.2 ms), PQ interval (175.8 vs. 198.0 ms), QRS interval (89.9 vs. 97.7 ms), and QTc interval (402.8 vs. 421.2 ms). We further examined ECG waveform prolongations related to BMI. Compared to other patient groups, the morbidly obese patients had the highest number of ECG segments with PQ interval (44% of the ECG samples), QRS duration (14%), and QTc duration (20%) above the normal limits. Conclusions: Morbid obesity predisposes patients to prolongation of cardiac conduction times. This might increase the risk of arrhythmias, stroke, and even sudden cardiac death.Peer reviewe

Inter-sleep stage variations in corrected QT interval differ between obstructive sleep apnea patients with and without stroke history

Obstructive sleep apnea (OSA) is related to the progression of cardiovascular diseases (CVD); it is an independent risk factor for stroke and is also prevalent post-stroke. Furthermore, heart rate corrected QT (QTc) is an important predictor of the risk of arrhythmia and CVD. Thus, we aimed to investigate QTc interval variations in different sleep stages in OSA patients and whether nocturnal QTc intervals differ between OSA patients with and without stroke history. 18 OSA patients (apnea-hypopnea index (AHI)≥15) with previously diagnosed stroke and 18 OSA patients (AHI≥15) without stroke history were studied. Subjects underwent full polysomnography including an electrocardiogram measured by modified lead II configuration. RR, QT, and QTc intervals were calculated in all sleep stages. Regression analysis was utilized to investigate possible confounding effects of sleep stages and stroke history on QTc intervals. Compared to patients without previous stroke history, QTc intervals were significantly higher (β = 34, p<0.01) in patients with stroke history independent of age, sex, body mass index, and OSA severity. N3 sleep (β = 5.8, p<0.01) and REM sleep (β = 2.8, p<0.01) increased QTc intervals in both patient groups. In addition, QTc intervals increased progressively (p<0.05) towards deeper sleep in both groups; however, the magnitude of changes compared to the wake stage was significantly higher (p<0.05) in patients with stroke history. The findings of this study indicate that especially in deeper sleep, OSA patients with a previous stroke have an elevated risk for QTc prolongation further increasing the risk for ventricular arrhythmogenicity and sudden cardiac death.publishedVersionPeer reviewe

Polysomnographic characteristics of severe obstructive sleep apnea vary significantly between hypertensive and normotensive patients of both genders

Purpose Hypertension is a common finding in patients with obstructive sleep apnea (OSA), but it has remained unclear whether or not the amount of disturbed breathing and characteristics of individual respiratory events differ between hypertensive and normotensive patients with severe OSA. Methods Full polysomnographic recordings of 323 men and 89 women with severe OSA were analyzed. Differences in the duration of individual respiratory events, total apnea and hypopnea times, and the percentage of disturbed breathing from total sleep time (AHT%) were compared between normotensive and hypertensive patients separately by genders. Furthermore, differences in the respiratory event characteristics were assessed between three AHT% groups (AHT

Desaturation delay, parameter for evaluating severity of sleep disordered breathing

Sleep apnea hypopnea syndrome (SAHS) is considered as a major health problem causing increased risk of cardiovascular problems. One of the most often used parameters to assess the severity of SAHS is apnea hypopnea index (AHI). It is calculated as the average amount of total cessations of breathing (apnea events) and partial reductions in breathing (hypopnea events) per hour of sleep. AHI only takes into account the total number of events regardless of their true nature. In this paper ambulatory polygraphic recordings of 19 male patients were analysed and the blood oxygen desaturation delay (BODD) studied in estimating the cardiovascular stress associated with sleep disordered breathing. The delay of the desaturation event occurring after apnea and hypopnea events were studied. Correlation with AHI and the delay parameter is modest and it shows variation between patients with similar AHI. This suggests that the delay parameter may provide additional information about the probably varying car-diovascular stress in patients with similar AHI and in the diagnostics of sleep disordered breathing in general

Novel parameters for evaluating severity of sleep disordered breathing and for supporting diagnosis of sleep apnea-hypopnea syndrome

Sleep apnea-hypopnea syndrome (SAHS) is a complex public health problem causing increased risk of cardiovascular diseases. Traditionally, evaluation of the severity of the disease is based on Apnea-Hypopnea Index (AHI). It is defined as the average number of apnea and hypopnea events per hour during sleep. However, e.g. the total duration and the morphology of the recorded events are not considered when evaluating the severity of the disease. This is surprising, as increasing the length of apnea and hypopnea events will most likely lead to longer and deeper oxygen desaturation events. Obviously, this is physiologically more stressful and may have more severe health consequences than shorter and shallower desaturation events. Paradoxically, the lengthening of apnea and hypopnea events may even lead to a decrease in AHI and oxygen desaturation index (ODI). This raises the question of whether additional information is needed besides AHI and ODI for the evaluation of the severity of SAHS and its potential cardiovascular consequences. In the present paper, several novel parameters are introduced to bring additional information for evaluation of the severity of SAHS. Besides the number of events per hour, that AHI and ODI takes into account, the duration of the breathing cessations and the morphology of the oxygen desaturation events are considered as important factors that may influence the daytime fatigue and also the related cardiovascular problems. In this study diagnostic ambulatory polygraphy recordings of 19 male patients were retrospectively analysed. Importantly, the novel parameters showed significant variation amongst patients with similar AHI. For example, the correlation between AHI and the Obstruction severity-parameter was only moderate (r=0.604,

Desaturation event characteristics and mortality risk in severe sleep apnea

Obstructive sleep apnea (OSA) is a public health problem with severe health consequences. The current OSA severity estimation is based on the average number of breathing cessation and desaturation events per hour of sleep, neglecting the individual event characteristics. The aim of the current study was to evaluate desaturation event morphology in deceased and matched control patients with severe OSA. 12 deceased and 12 AHI, age, BMI and follow-up time matched alive control patients with severe OSA were analyzed. Desaturation event durations, depths, and areas of the deceased and alive control patients were compared. Also the effect of different baseline level selection in the desaturation depth analysis was investigated. Patient demographics, apnea-hypopnea-index (AHI) and oxygen-desaturation-index (ODI) did not differ statistically significantly between the groups. The average oxygen saturation levels were statistically significantly lower 89.8% vs. 93.2% (p=0.002) in the deceased patients compared to the alive controls. The median desaturation event duration 31.8s vs. 25.9s (p=0.017), depth 15.0% vs. 9.5% (p=0.006) and area 349.9s% vs. 201.4s% (