Atrial Electromechanical Function Research Articles

Significance of Left Atrial Electromechanical Function for Atrial Fibrillation Prediction after Cardiac Surgery

Background: Postoperative atrial fibrillation (POAF) is the most important type of secondary AF. POAF is a complication in approximately one-third of patients undergoing cardiac surgery. The duration from P-wave onset on ECG to the peak of the A’ lateral wave on tissue Doppler imaging (PA-TDI) provides a reliable estimation of total atrial conduction time. Objective: To evaluate the efficacy of the PA-TDI duration for predicting post-operative atrial fibrillation in patients undergoing cardiac surgery. Patients and methods: This prospective study was conducted at national heart institute for 70 patients who were eligible and planned for undergoing cardiac surgery. Patients were divided into 2 groups according to the presence of post-operative AF. Accordingly, patients in the study were divided into group (I) that included patients who developed POAF and group (II), which included patients who remained in sinus rhythm and did not develop POAF. Results: PA-TDI duration in group I was longer than in group II with highly significant difference between the two groups with P-value < 0.001. It was found that PA-TDI duration (≥ 171.5 ms) has sensitivity equal to 91 and specificity 95%. Conclusion: PA interval measured by TDI preoperatively seems to be a simple method to predict incidence of POAF in patients undergoing cardiac surgery and it may be part of preoperative cardiovascular examination. The current study suggests that longer PA-TDI duration to be additive to conventional risk factors and biomarkers in predicting POAF and that PA-TDI duration is a predictor of POAF, and the best cut off value of PA-TDI duration for POAF is 171.5 ms.

Acute Effects of Red Bull Energy Drinks on Atrial Electromechanical Function in Healthy Young Adults

Energy drinks (EDs) are widely consumed by adolescents and young adults. Almost all kinds of arrhythmias have been reported following EDs consumption, most of which is atrial fibrillation (AF). Atrial conduction time prolongation and heterogeneous sinusal impulses propagation to the atriums are the key electrophysiological mechanisms leading AF. We aimed to evaluate the acute effects of Red Bull ED ingestion on atrial electromechanical conduction times in healthy young adults. After a 12-hour fasting, 54 healthy young adults consumed 330 mL of Red Bull ED. Atrial electromechanical coupling (PA), intra-atrial electromechanical delay (intra-AEMD), and interatrial electromechanical delay (inter-AEMD) were measured at baseline and 2-hour after Red Bull ED ingestion by echocardiographic tissue-Doppler imaging (TDI) method. PA-lateral (49.7 ± 11.2 vs 54.1 ± 11.0 msn, p = 0.001) and PA-septal (40.8 ± 9.1 vs 43.7 ± 10.5 msn, p = 0.032) times were statistically significantly prolonged after Red Bull ED ingestion. There was also a statistically significant increase in the duration of inter-AEMD (14.4 ± 10.6 vs 18.1 ± 8.5 msn, p = 0.010) after ED ingestion. It was showed that even a single can of ED can acutely increase atrial electromechanical conduction times in young adults. These findings may be the cause of ED-associated AF.

The effects of ivabradine on left atrial electromechanical function in patients with systolic heart failure

Heart rate (HR) reduction with ivabradine improves left ventricle filling by the prolongation of the diastolic time and increases stroke volume. But, it remains unclear what ivabradine's effect is on atrial conduction time and atrial mechanical functions. The aim of our study was to evaluate in stable outpatients with systolic heart failure (HF) the 3months effect of ivabradine on atrial conduction time and mechanical functions. We evaluated prospectively 43 (31 males, 12 females) patients with HF. Before and after treatment, all patients were evaluated by transthoracic M mode, two dimensional (2D), pulsed-wave (PW), continuous wave (CW), color flow and tissue Doppler imaging (TDI), and LA volumes were obtained apical four-chamber views by a disc's method. LA maximum volume (Vmax) at the end-systolic phase, LA minimum volume (Vmin) at the end-diastolic phase, and LA volume before atrial systole (Vp) were evaluated. The LA function parameters were calculated as follows: LA passive emptying volume = Vmax - Vp; LA passive emptying fraction = [(Vmax - Vp)/Vmax] × 100%, LA active emptying volume = Vp - Vmin; LA active emptying fraction = [(Vp - Vmin)/Vp] × 100%. Thirty men and 13 women with mean ± SD age of 63.9 ± 10.1years were included in this study. Resting heart rate was significantly reduced after ivabradine treatment. There were no significantly difference in LVEF, and E/A before and after ivabradine treatment. LA diameter and Vmin were similar before and after ivabradine treatment (p = 0.793 and p = 0.284). However, Vmax and Vp were significantly decreased after ivabradine treatment (p = 0.040 and p = 0.012). Moreover, LA active emptying volume and LA active emptying fraction were significantly decreased after ivabradine treatment (p = 0.030 and p = 0.008). The PA lateral, septal, and tricuspid durations were significantly reduced after ivabradine treatment (p < 0.001, p < 0.001, and p = 0.002, respectively). Interatrial electromechanical delay and right intra-atrial electromechanical delay were significantly decreased after ivabradine treatment (33.7 ± 12.7 vs 26.2 ± 10.1, p = 0.001; and 14.1 ± 6.1 vs 9.2 ± 6.8, p < 0.001). The present study demonstrated that adding ivabradine to the standard therapy reduced HR and improves significantly LA electrical and mechanical functions in systolic HF patients.

Nonthyroidal Illness Syndrome in Cardiac Illness Involves Elevated Concentrations of 3,5-Diiodothyronine and Correlates with Atrial Remodeling

Background: Although hyperthyroidism predisposes to atrial fibrillation, previous trials have suggested decreased triiodothyronine (T₃) concentrations to be associated with postoperative atrial fibrillation (POAF). Therapy with thyroid hormones (TH), however, did not reduce the risk of POAF. This study reevaluates the relation between thyroid hormone status, atrial electromechanical function and POAF. Methods: Thirty-nine patients with sinus rhythm and no history of atrial fibrillation or thyroid disease undergoing cardiac surgery were prospectively enrolled. Serum concentrations of thyrotropin, free (F) and total (T) thyroxine (T₄) and T₃, reverse (r)T₃, 3-iodothyronamine (3-T₁AM) and 3,5-diiodothyronine (3,5-T₂) were measured preoperatively, complemented by evaluation of echocardiographic and electrophysiological parameters of cardiac function. Holter-ECG and telemetry were used to screen for POAF for 10 days following cardiac surgery. Results: Seven of 17 patients who developed POAF demonstrated nonthyroidal illness syndrome (NTIS; defined as low T₃ and/or low T₄ syndrome), compared to 2 of 22 (p < 0.05) patients who maintained sinus rhythm. In patients with POAF, serum FT₃ concentrations were significantly decreased, but still within their reference ranges. 3,5-T₂ concentrations directly correlated with rT₃ concentrations and inversely correlated with FT₃ concentrations. Furthermore, 3,5-T₂ concentrations were significantly elevated in patients with NTIS and in subjects who eventually developed POAF. In multivariable logistic regression FT₃, 3,5-T₂, total atrial conduction time, left atrial volume index and Fas ligand were independent predictors of POAF. Conclusion: This study confirms reduced FT₃ concentrations in patients with POAF and is the first to report on elevated 3,5-T₂ concentrations in cardiac NTIS. The pathogenesis of NTIS therefore seems to involve more differentiated allostatic mechanisms.

Relationship between CHA2DS2-VASc score and atrial electromechanical function in patients with paroxysmal atrial fibrillation: A pilot study

BackgroundCHA2DS2-VASc score is the most widely preferred method for prediction of stroke risk in patients with atrial fibrillation. We hypothesized that CHA2DS2-VASc score may represent atrial remodeling status, and therefore echocardiographic evaluation of left atrial electromechanical remodeling can be used to identify patients with high risk. MethodsA total of 65 patients who had documented diagnosis of paroxysmal atrial fibrillation (PAF) were divided into three risk groups according to the CHA2DS2-VASc score: patients with low risk (score=0, group 1), with moderate risk (score=1, group 2), and with high risk score (score ≥2, group 3). We compared groups according to atrial electromechanical intervals and left atrium mechanical functions. ResultsAtrial electromechanical intervals including inter-atrial and intra-atrial electromechanical delay were not different between groups. However, parameters reflecting atrial mechanical functions including LA phasic volumes (Vmax, Vmin and Vp) were significantly higher in groups 2 and 3 compared with group 1. Likewise, LA passive emptying volume (LATEV) in the groups 2 and 3 was significantly higher than low-risk group (14.12±8.13ml/m2, 22.36±8.78ml/m2, 22.89±7.23ml/m2, p: 0.031). Univariate analysis demonstrated that Vmax, Vmin and Vp were significantly correlated with CHA2DS2-VASc score (r=0.428, r=0.456, r=0.451 and p<0.001). Also, LATEV (r=0.397, p=0.016) and LA active emptying volume (LAAEV) (r=0.281, p=0.023) were positively correlated with CHA2DS2-VASc score. In the ROC analysis, Vmin≥11ml/m2 has the highest predictive value for CHA2DS2-VASc score ≥2 (88% sensitivity and 89% specificity; ROC area 0.88, p<0.001, CI [0.76–0.99]). ConclusionEchocardiographic evaluation of left atrial electromechanical function might represent a useful method to identify patients with high risk.

P-wave duration dispersion in patients with lichen planus

Dear Editors, We have read the article “Increased P-wave dispersion (PWD) in patients with newly diagnosed lichen planus (LP)” by Sahin et al. (1). These researchers aimed to investigate PWD in patients with LP, and they concluded that PWD increased in the surface electrocardiographic measurements of LP patients. This result may be important for the early detection of subclinical cardiac involvement. This study provides important information on this clinically relevant condition. The ready availability of this parameter at no additional cost may encourage its wider use in clinical practice in the future. The authors should be commended for their contribution. LP is a chronic inflammatory autoimmune mucocutaneous disease. Although its pathogenesis is not fully understood, it is recognized as a chronic disease that is almost certainly immunologically mediated. Several studies have shown that prolonged PWD has predictive value for the development of atrial fibrillation (AF) in patients with or without apparent heart disease. In addition to predicting AF, prolonged PWD has also been observed in various clinical settings. Cross-sectional studies have demonstrated that subjects with hypertension, obesity, diabetes, and coronary artery disease have prolonged PWD compared with controls. Apart from the above-mentioned diseases, some conditions, such as seasonal variation, alcohol intake, and caffeine ingestion, have been demonstrated to affect PWD. Hepatic steatosis is associated with metabolic and hemodynamic abnormalities induced by insulin resistance and severe inflammation. Increased PWD may indicate a risk of atrial arrhythmia in patients with inflammation-based hepatic steatosis (2). Prolonged PWD has also been observed in patients with stable asthma (3). Furthermore, PWD is independently associated with renal function. In a previous study, researchers showed that PWD is a novel parameter that may accurately predict AF and was increased in renal failure patients (4). Prolonged atrial electromechanical coupling time and impaired mechanical atrial functions may be related to the increased incidence of arrhythmias. Thyroid hormone levels may affect atrial electromechanical function. In a previous study, researchers demonstrated prolonged PWD in patients with thyroid disorders (5). Additionally, some medications, such as propylthiouracil and methimazole, were found to reduce the P wave duration and dispersion (6). Furthermore, antihypertensive therapy, such as short-term treatment with quinapril, irbesartan, atenolol, and nebivolol, reduces the duration of PWD. This effect is independent of blood pressure and heart rate changes. Additionally, lipid-lowering therapy significantly reduced PWD, a finding that may be important in the prevention of AF in hyperlipidemic patients. In conclusion, although prolonged PWD was observed in the surface electrocardiographic measurements of LP patients as presented in the current study, PWD may be affected by various conditions and medications. Therefore, further studies should evaluate prolonged PWD-related conditions.

Impaired atrial electromechanical function and atrial fibrillation promotion in alloxan-induced diabetic rabbits

Diabetes mellitus (DM) is an independent risk factor for atrial fibrillation (AF). However, the underlying mechanisms are still not clearly elucidated. The aim of this study was to evaluate the atrial electromechanical function, atrial electrophysiological changes and AF inducibility in alloxan-induced diabetic rabbits. In 8 alloxan-induced diabetic rabbits and 8 controls, we evaluated atrial electromechanical function by tissue Doppler imaging. Isolated Langendorff-perfused rabbit hearts were prepared to measure atrial refractory effective period (AERP) and its dispersion (AERPD), interatrial conduction time (IACT) and vulnerability to AF. Atrial interstitial fibrosis was evaluated by Sirius-Red staining. Compared with controls, left atrial lateral wall Pa'-start interval (Pastart) and right atrial wall Pastart were increased in diabetic rabbits. AERPD was increased and IACT was prolonged in diabetic rabbits. Inducibility of AF in diabetic group was significant higher than controls (6/8 vs. 1/8, p < 0.05). Extensive interstitial fibrosis was observed in the DM group (p < 0.01). Correlation analysis showed that right atrial wall Pastart, Pa'-peak interval (Papeak) and total electromechanical activity (TEMA); left atrial lateral wall Papeak and TEMA, left atrial posterior wall TEMA, and IACT were correlated with atrial areas of fibrosis. Atrial electromechanical function is impaired in diabetic rabbits, and is associated with atrial fibrosis and interatrial electrical conduction delay.

RELATIONSHIP BETWEEN ATRIAL ELECTROMECHANICAL FUNCTION IMPAIRMENT AND ATRIAL FIBRILLATION IN ALLOXAN-INDUCED DIABETIC RABBITS

ObjectivesTo evaluate the potential relationship between atrial electromechanical function and atrial fibrillation (AF) inducibility in alloxan-induced diabetic rabbits.MethodsIn 8 alloxan-induced diabetic rabbits and 8 controls, we measured atrial electromechanical coupling...

Evaluation of atrial electromechanical delay and left atrial mechanical function in patients with obstructive sleep apnea

The aim of this study was to evaluate atrial electromechanical delay measured by tissue Doppler imaging and left atrial mechanical function in patients with obstructive sleep apnea (OSA). Fourty-seven moderate-to-severe OSA patients who were newly diagnosed by polysomnography (Apnea-hypopnea index ≥ 15 events/h, 32 males, mean age 49.4 ± 11.5) and 30 patients who had no OSA in polysomnography (Apnea-hypopnea index < 5 events/h, 21 males, mean age 45.4 ± 9.1) were included in the study. Using tissue Doppler, diastolic functions, atrial electromechanical coupling were measured from the lateral mitral, septal, and tricuspid annulus. Inter, intra, and left atrial electromechanical delay were calculated (lateral-tricuspid, septum-tricuspid, lateral-septal). Left atrial volumes (maximal, minimal, and presystolic) were measured by the method of discs in the apical four-chamber view and were indexed to body surface area. Mechanical function parameters of the left atrium were also calculated. Interatrial, intraatrial, and left atrial electromechanical delays were significantly higher in the OSA group compared to the control group. Passive emptying fraction was significantly decreased, volume at the beginning of atrial systole and active emptying volume were significantly increased in OSA patients compared to the controls. The apnea-hypopnea index was significantly associated with interatrial and intraatrial electromechanical delay, passive emptying fraction, and conduit volume. Electromechanical delay was markedly prolonged and left atrial electromechanical function was impaired in untreated OSA patients. These impairments worsen with increasing severity of OSA.

Assessment of atrial electromechanical function by tissue Doppler echocardiography and atrial fibrillation promotion in alloxan-induced diabetic rabbits: an experimental study

PurposeDiabetes mellitus is an independent risk factor for atrial fibrillation (AF). However, the underlying mechanisms are still not clearly elucidated. The aim of this study was to evaluate atrial electromechanical...

Assessment of atrial regional and global electromechanical function by tissue velocity echocardiography: a feasibility study on healthy individuals

BackgroundThe appropriate evaluation of atrial electrical function is only possible by means of invasive electrophysiology techniques, which are expensive and therefore not suitable for widespread use. Mechanical atrial function is mainly determined from atrial volumes and volume-derived indices that are load-dependent, time-consuming and difficult to reproduce because they are observer-dependent.AimsTo assess the feasibility of tissue velocity echocardiography (TVE) to evaluate atrial electromechanical function in young, healthy volunteers.Subjects and methodsWe studied 37 healthy individuals: 28 men and nine women with a mean age of 29 years (range 20–47). Standard two-dimensional (2-D) and Doppler echocardiograms with superimposed TVE images were performed. Standard echocardiographic images were digitized during three consecutive cardiac cycles in cine-loop format for off-line analysis. Several indices of regional atrial electrical and mechanical function were derived from both 2-D and TVE modalities.ResultsSome TVE-derived variables indirectly reflected the atrial electrical activation that follows the known activation process as revealed by invasive electrophysiology. Regionally, the atrium shows an upward movement of its walls at the region near the atrio-ventricular ring with a reduction of this movement towards the upper levels of the atrial walls. The atrial mechanical function as assessed by several TVE-derived indices was quite similar in all left atrium (LA) walls. However, all such indices were higher in the right (RA) than the LA. There were no correlations between the 2-D- and TVE-derived variables expressing atrial mechanical function. Values of measurement error and repeatability were good for atrial mechanical function, but only acceptable for atrial electrical function.ConclusionTVE may provide a simple, easy to obtain, reproducible, repeatable and potentially clinically useful tool for quantifying atrial electromechanical function.

The electromechanical effects of pacing at different sites within the right atrium.

To compare high right atrium (HRA) with right atrial appendage (RAA) pacing with respect to atrial electromechanical function. Eleven patients undergoing elective electrophysiological studies were studied in order directly to compare atrial conduction acutely associated with HRA and RAA pacing. Twenty-five patients with chronically implanted, active fixation leads in the HRA were compared with an age and sex matched group of 25 patients with chronically implanted, passive fixation leads in the RAA. For both studies recordings were taken in sinus rhythm then repeated when paced. Measured time intervals were intra- and interatrial activation times. P wave duration and time to onset of atrial systolic blood flow. Right atrial pacing, when compared with sinus rhythm, significantly prolongs the interatrial activation time, the P wave duration and the time to onset of right and left atrial blood flow irrespective of site paced. Comparing the RAA group with the HRA group, there were no statistical differences for any of the measured parameters. High right atrial free wall or the right atrial appendage pacing, when compared with sinus rhythm, is significantly detrimental to atrial electromechanical function. There is, however, no demonstrable difference between the two sites.