Association of Fragmented QRS with Subclinical Left Ventricular Dysfunction in Patients with Obstructive Sleep Apnea

Analysis of QRS complex morphology in children and adolescents with obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) leads to many cardiovascular, neurologic, metabolic, and neurocognitive consequences. Conduction deficits, deviations in electrical axis, and changes in QRS morphology reflect the impairments in cardiac muscle activity and underlie the cardiovascular complications of OSAS. Here we aimed to determine the relationship between OSAS and changes in the cardiac conduction system in children and adolescents. During the 6-month duration of the study, all children having the diagnosis of OSAS in Sleep and Disorders Unit following a full-night polysomnography (PSG) were consecutively evaluated. ECGs were performed and analyzed in the Division of Pediatric Cardiology, Department of Pediatrics. The maximum spatial vector size (QRSmax), QRS electrical axis (EA), left and right ventricular hypertrophy, and the presence of fragmented QRS (fQRS) or prolonged R or S wave were examined in detail. A total of 17 boys with OSAS and 13 healthy boys participated in the study. The mean QRSmax and the QRSmax on V5 derivative were significantly lower in the patient group compared to those in the control group (p = 0.011 and p = 0.017, respectively). EA was similar between the two groups. While none of the patients with OSAS nor the control group had left ventricular hypertrophy, only one boy with OSAS had right ventricular hypertrophy according to ECG-derived analysis. The percentage of fQRS or notched R or S waves was significantly higher in patients with OSAS compared to healthy controls (p = 0.035), especially in children below the age of 5 years (p = 0.036).  Conclusion: This study demonstrated that male children and adolescents with OSAS have a combination of QRS complex changes characterized by low QRS voltages, and increased frequency of fragmented QRS. These findings reflect that the electrical remodeling and structural remodeling of the myocardium are considerably affected by OSAS in children and adolescents, leading to ventricular changes and intraventricular conduction problems. What is Known: • Pediatric obstructive sleep apnea syndrome (OSAS) characterized by recurrent intermittent hypoxemia, hypercapnia, and sleep fragmentation results in sympathetic nervous system activation, increased inflammation, and hypoxic endothelial dysfunction. When left untreated, OSAS leads to many cardiovascular, neurologic, metabolic and neurocognitive consequences, and also to sudden infant death syndrome in young children, probably due to the involvement of the cardiac conduction system. What is New: • This study demonstrated that mean QRSmax was significantly lower in male children and adolescents with OSAS, reflecting the structural and electrical remodeling of the myocardium, and one boy with OSAS had RVH according to ECG-derived analysis. The percentage of fQRS or notched R or S waves was much higher in boys with OSAS, especially in children below the age of five years. These finding showed that myocardium was considerably affected to impair the intraventricular conduction in younger children with OSAS.

Relationship between presystolic wave and subclinical left ventricular dysfunction as assessed by myocardial performance index in patients with metabolic syndrome

The myocardial performance index (MPI) is an index that shows both systolic and diastolic functions of the ventricle. Presystolic wave (PSW) is a late diastolic wave encountered in the left ventricular outflow tract (LVOT) and is associated with increased left ventricular stiffness and decreased left ventricular compliance. In our study, MPI was compared between patients with metabolic syndrome and normal patients, and we also investigated whether PSW could predict subclinical left ventricular dysfunction (SCLVD) in patients with metabolic syndrome. A total of 119 patients, 59 with metabolic syndrome and 60 healthy volunteers, were included in our study. Our study is a two-center prospective study. The patient groups were compared in terms of demographic, laboratory and echocardiographic parameters. Univariate and multivariate regression analyzes were performed to detect predictors of SCLVD. Higher MPI and PSW were found in patients with metabolic syndrome compared to the normal population (0.56 ± 0.11 vs. 0.46 ± 0.07, p < 0.001, 34 (57.6%) vs. 19 (31.7%), p = 0.004, respectively). MPI was found to be higher in patients with metabolic syndrome with PSW ( +) (0.59 ± 0.13 vs. 0.52 ± 0.05, p = 0.005). Smoking and PSW were found as Independent Predictors of Subclinical Left Ventricular Dysfunction in the Multivariate Logistic Regression Analysis Model (OR 0.146, 95%CI 0.028-0.767, p = 0.023 and OR 10.689, 95%CI 2.176-52.515, p = 0.004, respectively). Higher MPI and SCLVD were detected in patients with metabolic syndrome compared to the normal population. In addition, PSW positivity was associated with SCLVD in this patient group.

Electrocardiographic alterations in patients with chronic obstructive pulmonary disease

Patients with chronic obstructive pulmonary disease (COPD) have an increased risk for cardiovascular events, and electrocardiography has an important role in detecting cardiac side effects of COPD-related hypoxia.

Presystolic Wave is Associated with Subclinical Left Ventricular Dysfunction Assessed by Myocardial Performance Index in Type 2 Diabetes Mellitus

BACKGROUND

Myocardial performance index (MPI), demonstrates both systolic and diastolic functions of the left ventricle. Presystolic wave (PSW) is frequently detected on Doppler examination of the left ventricular outflow tract and possible mechanism of PSW is impaired LV compliance and left ventricular stiffness.

OBJECTIVE

To investigate the relationship between PSW and MPI in type 2 diabetic patients.

METHOD

A total of 129 type 2 diabetic patients were included in this study. Patients were divided into two groups according to the presence of PSW on Doppler echocardiography. There were 90 patients (38 male, mean age 57.77 ± 10.91 years) in the PSW-positive group and 39 patients (13 male; mean age: 55.31 ± 11.29 years) in the PSW-negative group. The p values of < 0.05 were considered statistically significant.

RESULTS

MPI was higher in PSW- positive group (0.63 ± 0.17vs 0.52 ± 0.13, p < 0.001). In addition, subclinical left ventricle dysfunction (LVD) was higher in the PSW- positive group (p = 0.029). Univariate analysis showed that the presence of PSW associated with abnormal MPI (p = 0.031). Pearson correlation analysis showed that PSW velocity correlated with MPI (r: 0.286, p = 0.006).

CONCLUSION

Presence of the PSW on Doppler examination was associated with subclinical LV dysfunction in patients with DM type 2. This easy-to-perform echocardiographic parameter may be related to subclinical LVD among patients with type 2 DM.

Ventricular Arrhythmias in Patients with Obstructive Sleep Apnea

Obstructive Sleep Apnea (OSA) is a prevalent condition thought to increase in the future. Being mostly undiagnosed, the most serious complications are cardiovascular diseases, among which are arrhythmias. Controversy remains as to whether OSA is a primary etiologic factor for ventricular arrhythmias, because of the high incidence of cardiovascular comorbidities in OSA patients. Howev-er, there is mostly a strong evidence of a relation between OSA and ventricular arrhythmias. A few mechanisms have been proposed to be responsible for this association and some electrocardiographic changes have also been demonstrated to be more frequent in OSA patients. Treatment of OSA with Continuous Positive Airway Pressure (CPAP) has the potential to reduce arrhythmias and confer a mortality benefit.

The Influence of Sleep Apnea on 24-Hour and Nocturnal ECG and Blood Pressure Parameters in Patients with Acute Heart Failure

OBJECTIVE

To investigate the influence of sleep apnea (SA) on ECG and blood pressure (BP) monitoring parameters in patients with acute heart failure (AHF).

METHODS

A total of 51 hospitalized patients with AHF (13 women, 38 men, mean age 60.8 years) underwent 24-hour combined monitoring of ECG and BP and SA testing before discharge. Heart rhythm (mean heart rate, arrhythmias, pauses, QT interval, heart rate variability) and BP (mean systolic and diastolic values, variability, circadian variation) parameters were obtained for the whole day and for nighttime (22: 00-06: 00). Depending on SA severity, the patients were divided into two groups (respiratory event index, REI, < 15/h and ≥15/h). Comparisons of parameters between the two groups were performed using t test and χ2 test (alpha < 0.05 for significance).

RESULTS

A total of 29 (56.9%) patients had REI ≥15/h. In this group, the systolic and diastolic BP values (24-hour and nighttime) were significantly higher (p < 0.05). BP variability did not differ, and a markedly blunted circadian variation of both the systolic and diastolic values was observed. In the group with REI ≥15/h, we found a higher nocturnal versus diurnal mean heart rate ratio (p = 0.046) and a greater occurrence of nocturnal versus diurnal ventricular premature beats (p = 0.0098).

CONCLUSION

The presence of significant SA was found to influence the BP values and nocturnal ventricular ectopy in patients with stabilized AHF. SA, 24-hour ECG, and BP monitoring could provide important information with potential impact on patient management.

[Fragmented QRS. Relevance in clinical practice]

The QRS complex represents the electrical depolarization of ventricular myocardium. In the case of an undisturbed depolarization, the QRS complex has a normal configuration and duration, but abnormal electrical conduction leads to widening of the QRS complex. The block of one of the Tawara branches results in a typical bundle branch block pattern. A QRS complex that cannot be classified as bundle branch block due to an atypical configuration and contains notched R or S waves is called a fragmented QRS. The underlying pathophysiologies are manifold and include myocardial scars induced by ischemic heart disease, myocardial fibrosis due to other diseases, primary cardiac pathologies as well as systemic diseases with cardiac involvement. Pathologies on the cellular level, such as ion channel dysfunctions, also correlate with fragmented QRS. Besides the diagnostic relevance, fragmented QRS is known to have prognostic properties, for example in identifying high risk patients with coronary artery disease, cardiomyopathy, Brugada syndrome and acquired long QT syndrome; however, fragmented QRS may also be detected in ECGs of healthy individuals.