Propagation Of Sinus Impulses Research Articles

Study of P wave dispersion in patients with paroxysmal atrial fibrillation and its role in prediction of atrial fibrillation recurrence

BackgroundIt has been known that increased P wave duration and P wave dispersion reflect prolongation of intra-atrial and interatrial conduction time and the inhomogeneous propagation of sinus impulses, which are well-known electrophysiologic characteristics in patients with atrial arrhythmias and especially paroxysmal atrial fibrillation. The objective of this study was assessment of P wave dispersion value in cases with paroxysmal atrial fibrillation and its role in predicting recurrence.ResultsForty-eight patients with documented paroxysmal AF were subjected to clinical evaluation, electrocardiogram and routine Doppler echocardiogram. We found that a statistically significant association was detected between P wave dispersion and older age, diabetic and hypertensive cases with positive correlation also detected with left atrial dimension (LAD), left ventricle size and diastolic dysfunction grade. Mean corrected P wave dispersion and corrected QT interval were higher among cases using sotalol, ca channel blockers, among cases using nitrates and among cases with Morris index > 0.04. Higher mean value of corrected QT was associated with biphasic P v1 shape. Old age, female sex, P wave dispersion and QT wave dispersion are statistically significant predictors of PAF recurrence.ConclusionP wave dispersion in patients with paroxysmal atrial fibrillation was strongly correlated to older age, diabetic and hypertensive patients and also with left atrial dimension (LAD), left ventricle size and diastolic dysfunction grade. Also, mean corrected P wave dispersion can predict atrial fibrillation recurrence in patients with Morris index > 0.04, old age, female sex, and QT wave dispersion.

Increased P-wave dispersion in patients with obstructive sleep apnea syndrome: a meta-analysis.

Prolonged atrial conduction and inhomogeneous sinus impulse propagation may play a role in the initiation and maintenance of atrial tachyarrhythmias. Such a process could be reflected in inter-lead P-wave duration differences known as "P-wave dispersion" (PWD). Abnormal PWD may be related to obstructive sleep apnea syndrome (OSAS). A meta-analysis of the available publications was conducted. A MEDLINE, Web of Science, and Google Scholar search from 2000 to 2021 was performed. The keywords used for search were apnea AND "P wave dispersion." Case-control studies and surveys were selected as long as they included healthy subjects and subjects with diagnosed OSAS who did not have any other major health problems. PWD values and correlations between apnea-hypopnea indices (AHI) and PWD were used as outcome measures. Ten studies met the inclusion creteria, encompassing 773 patients with OSAS and 347 healthy controls. The mean ages of the patients withOSAS ranged from 6.9 to 58.8 years. The estimated average Hedges's g standardized mean difference in PWD values was equal to 1.883 (95% CI: 1.140 to 2.626, p < 0.001). The estimated average Fisher r-to-z transformed correlation coefficient between AHI and PWD was equal to 0.530 (95% CI: 0.075 to 0.985, p = 0.0225). Meta-regression analysis failed to find statistically significant correlations between the effect sizes and the mean age, male proportion, and the body mass index in the OSAS groups. OSAS is associated with increased PWD, which may predispose to atrial tachyarrythmias.

Endocardial electro-anatomic mapping in healthy horses: Normal sinus impulse propagation in the left and right atrium and the ventricles

Understanding the depolarisation pattern of the equine heart under normal physiologic conditions, and its relationship to the surface electrocardiogram (ECG), is of uppermost importance before any further research can be done about the pathophysiology of complex arrhythmias. In the present study, a 3D electro-anatomical mapping system was used to evaluate the qualitative and quantitative depolarisation patterns and correlation to the surface ECG of both the atrial and ventricular endocardium in seven healthy horses in sinus rhythm under general anaesthesia. Bipolar activation maps of the endocardium were analysed.The first atrial activation was located at the height of the terminal crest. Only one interatrial conduction pathway was recognised. The first and second P wave deflections represent the right and left atrial depolarisation, respectively. Bundle of His electrograms could be recorded in 5/7 horses. Left ventricular activation started at the mid septum and right ventricular activation started apically from the supraventricular crest. This was followed by separate depolarisations at the height of the mid free wall. Further ventricular depolarisation occurred in an explosive pattern. Electrically active tissue could be found in all pulmonary veins. In contrast to findings of previous studies, all parts of the ventricular depolarisation contributed to the surface ECG QRS complex. This study provides a reference for the normal sinus impulse endocardial propagation pattern and for conduction velocities in equine atria and ventricles.

Interatrial conduction time is early marker of disturbed impulse propagation in adults with slightly elevated blood pressure

Background/Aim. Interatrial conduction time is early marker of disturbed impulse propagation in adult with elevated blood pressure. The aim of our study was to evaluate significance of noninvasive echocardiographic marker of slow sinus impulse propagation (atrial conduction time) for the identification of persons with slightly elevated blood pressure and hypertension in adults. Methods. One hundred and forty nine adults with normal and elevated blood pressure were studied: 46 normotensive adults (group 1), 28 adults with elevated blood pressure and hypertension stage 1 (group 2) and 75 adults with hypertension stage 2 (group 3), based on the Joint National Committee 8 (JNC-8) hypertension guidelines. We studied P wave dispersion, reservoir function of the left atrium (LA), total emptying volume of the LA and total emptying fraction of the LA (LATEF). The atrial conduction time (ACT) was evaluated by the pulsed tissue Doppler, and expressed as interatrial and intraatrial conduction time. Results. The LATEF decreased progressively from the group 3 (64.8 ? 4.4%) to the group 2 (59.8 ? 5.2%) and the group 1 (55.6 ? 7.3%) (p &lt; 0.001). The P wave dispersion (55.1 ? 9.8 ms vs. 46.8 ? 3.1 ms vs. 43.1 ? 2.6 ms; p &lt; 0.01) and intra ACT were significantly prolonged only in the group 3 compared to the other groups (22.7 ? 11.0 ms vs. 8.4 ? 4.7ms vs. 5.6 ? 2.4 ms, respectively; p &lt; 0.001). Inter ACT significantly increased from the group 1 to the group 2 and the group 3 (15.6 ? 3.9 ms vs. 24.6 ? 5.7 ms vs. 50.4 ? 20 ms, respectively; p &lt; 0.05). Using a cut-off level of 19.5 ms, inter ACT could separate adults in the group 2 from the group 1 with a sensitivity of 85%, and specificity of 89% [area under receiver operating characteristic (ROC) curve 0.911]. Conclusion. Prolonged ACT estimated with the tissue Doppler may be useful for identification persons with slighty elevated blood pressure, and hypertension stage 1.

Evaluation of P wave dispersion as a predictor of atrial arrhythmias in dystrophinopathies

PURPOSE: Arrhythmias are one of the manifestations of cardiac involvement in dystrophinopathies. P-wave dispersion (PWD) has been known to be associated with inhomogeneous and discontinuous propagation of sinus impulses. In the present study, we aimed to investigate the role of PWD in patients with Duchenne (DMD) and Becker (BMD) muscular dystrophies. METHODS: It is a retrospective cohort study. The study population consisted of 68 patients with dystrophinopathy and age and sex matched 68 healthy control subjects. Patients with diabetes …

IRON ISOMALTOSIDE DIMINISHES ATRIAL ELECTRICAL INHOMOGENEITY IN CHRONIC HEART FAILURE WITHOUT ALTERING ATRIAL SIZE: A FERRIC-HF II SUBSTUDY

Atrial sinus impulse propagation is critically dependent on atrial energetics. Enhanced atrial electrical inhomogeneity, as reflected by a prolonged P wave dispersion (Pd), can result from impaired energetics and heralds atrial fibrillation and worsening chronic heart failure (CHF). Because iron

P-Wave Morphology, Amplitude, Duration and Dispersion in Atrial Arrhythmias

The detailed analysis of the P-wave duration and dispersion by means of conventional electrocardiography with the 12 standard surface leads in the stratification of patients suffering from AF is a recognized universal approach. P-wave dispersion (PWD) has received increasing attention in the field of non-invasive electrophysiology studying atrial arrhythmias and has been examined in a broad range of clinical settings including cardiovascular and non-cardiovascular diseases. It is well accepted that, not only the P-wave duration, but also the P-wave morphology and dispersion have the potential to give information about the anatomical substrate predisposing to AF. Patients with diseased atrial myocardium with fibrotic changes may develop abnormal electrophysiological alterations. Therefore, these atrial anisotropic characteristics may play an important role in creating reentry circuits by causing inhomogeneous and discontinuous propagation of the impulse in the atrial tissue. The altered atrial myocardium may generate unidirectional block, conduction delay and reentrant atrial rhythms. The P-wave of the electrocardiogram may show alterations that can be associated with atrial arrhythmias and AF. PWD is considered a noninvasive electrocardiographic marker for atrial remodeling and predictor for AF. It has been shown that increased P-wave duration and PWD reflect prolongation of intra-atrial and inter-atrial conduction time. In patients prone to develop atrial arrhythmias and AF, PWD reflects prolonged, inhomogeneous and anisotropic distribution of connections between myocardial fibers resulting in discontinuous anisotropic propagation of sinus impulses and atrial conduction. PWD is considered as a sensitive and specific ECG marker and predictor of atrial arrhythmias and paroxysmal AF.

Correlation of P-wave dispersion with insulin sensitivity in obese adolescents.

P-wave dispersion is a new and simple electrocardiographic marker that has been reported to be associated with inhomogeneous and discontinuous propagation of sinus impulses. In the present study, we evaluated P-wave dispersion in obese adolescents and investigated the relationship between P-wave dispersion, cardiovascular risk factors, and echocardiographic parameters. We carried out a case-control study comparing 150 obese adolescents and 50 healthy controls. Maximum and minimum P-wave durations were measured using a 12-lead surface electrocardiogram, and P-wave dispersion was calculated as the difference between these two measures. Echocardiographic examination was also performed for each subject. Multivariate linear regression analysis with stepwise variable selection was used to evaluate parameters associated with increased P-wave dispersion in obese subjects. Maximum P-wave duration and P-wave dispersion were significantly higher in obese adolescents than control subjects (143±19 ms versus 117±20 ms and 49±15 ms versus 29±9 ms, p<0.0001 for both). P-wave dispersion was positively correlated with body mass index, waist and hip circumferences, systolic and diastolic blood pressures, total cholesterol, serum levels of low-density lipoprotein cholesterol, triglycerides, glucose, and insulin, homoeostasis model assessment for insulin resistance score, left ventricular mass, and left atrial dimension. P-wave dispersion was negatively correlated with high-density lipoprotein cholesterol levels. By multiple stepwise regression analysis, left atrial dimension (β: 0.252, p=0.008) and homoeostasis model assessment for insulin resistance (β: 0.205; p=0.009) were independently associated with increased P-wave dispersion in obese adolescents. Insulin resistance is a significant, independent predictor of P-wave dispersion in obese adolescents.

P-wave dispersion: What we know till now?

P-wave dispersion is defined as the difference between the maximum and the minimum P-wave duration recorded from multiple different-surface ECG leads. It has been known that increased P-wave duration and P-wave dispersion reflect prolongation of intraatrial and interatrial conduction time and the inhomogeneous propagation of sinus impulses, which are well-known electrophysiologic characteristics in patients with atrial arrhythmias and especially paroxysmal atrial fibrillation. Extensive clinical evaluation of P-wave dispersion has been performed in the assessment of the risk for atrial fibrillation in patients without apparent heart disease, in hypertensives, in patients with coronary artery disease, in patients undergoing coronary artery bypass surgery, in patients with congenital heart diseases, as well as in other groups of patients suffering from various cardiac or non-cardiac diseases. In this paper, we aimed to summarize the measurement methods, current use in different clinical situations, strengths and limitations of the of P-wave dispersion.

Transmural dispersion of repolarization and atrial electromechanical coupling: complementary indices for quantifying cardiac electrical heterogeneity in patients with conversion disorder.

Dear editor We read with great interest the article entitled “P-wave and QT dispersion in patients with conversion disorder” by Izci et al1 in Therapeutics and Clinical Risk Management. In this well designed research, Izci et al studied QT dispersion (QTd) and P-wave dispersion (Pd) in patients with conversion disorder (CD). In conclusion, they reported that corrected QT (QTc) and QTd values were significantly altered in patients with CD when compared to healthy controls, but that there was no significant difference in terms of Pd. It has been postulated that the relationship between somatoform disorders and CD is related to altered autonomic functions.2 These changes may affect the refractory period and conduction velocity of the heart. In line with these assumptions, heterogeneity in the duration of the ventricular repolarization phase leading to arrhythmias may also be seen in patients with CD. As in this study, QTd is the most frequently used parameter to detect ventricular inhomogeneity. However, reproducibility of QT interval measurements is low in both manual and automatic measurements and interobserver and intraobserver variability of QTd is very high.3,4 Quantifying the inhomogeneity of the myocardium, transmural dispersion of repolarization (TDR) has also been used since the beginning of the 2000s in addition to QTd.5 There are three types of myocyte, ie, endocardial, epicardial, and midmyocardial M cells, each having different electrophysiological properties in the ventricular myocardium. Mid-myocardial M cells have typically the longest repolarization phase. The repolarization phase of the midmyocardial M cells continues until the end of the T-wave. However, the repolarization phase of the epicardial cells ends at the peak of the T-wave. The time between the peak and end of the T-wave is known as the Tp-e interval, and is an index of the TDR.5 In addition, the Tp-e/QT ratio has also been used as an electrical dispersion index for the myocardium, showing arrhythmic risk. The role of the TDR in evaluation of arrhythmic risk has been demonstrated in coronary artery disease and in the Brugada, short QT, and long QT syndromes. Previously, we showed that the Tp-e interval was increased in patients with obstructive sleep apnea.6 On the other hand, the basic electrophysiological characteristics of the atrium that predispose to atrial arrhythmias are prolongation of intra-atrial and interatrial conduction times and heterogeneous propagation of sinus impulses. Pd is an accepted marker of atrial depolarization heterogeneity and the altered propagation of sinus impulses found to be associated with increased risk of atrial fibrillation. Although prolonged Pd values were found to be correlated with atrial fibrillation, it is controversial whether Pd is related to heterogeneity of atrial conduction or to other factors. Furthermore, reproducibility of P-wave measurements is low in both manual and automatic measurements and interobserver and intraobserver variability is very high. Atrial electromechanical coupling (AEC) can be assessed by electrocardiography-integrated tissue Doppler imaging and provides a means to determine the atrial mechanical and electrical event. Analysis of AEC by tissue Doppler imaging allows precise analysis of AEC between different regions. Moreover, measurement of AEC may suggest an inhomogeneous propagation of sinus impulses in different cardiac sites. Autonomic dysregulation and altered sympathovagal balance, as in somatoform disorders, may account for heterogeneity in atrial conduction properties. Measurement of AEC has been done in patients with psoriasis, ankylosing spondylitis, hyperthyroidism, end-stage renal disease, and hypertension.7–9 Regarding these observations, autonomic imbalance may cause atrial depolarization and sinus impulse propagation abnormalities leading to altered AEC. Our opinion is that, if AEC intervals had been measured in this study, they may have been found to be altered in patients with CD. Further, regarding the forementioned observations, if Izci et al had measured the Tp-e interval and Tp-e/QT ratio in their study, they might have found an increased TDR in their patients with CD. Considering all the data about Pd, AEC, QTd, and TDR, their study might have revealed the effects of CD on electrical heterogeneity of the myocardium more completely in many respects.

Systemic Effects of Perinatal Asphyxia

Perinatal asphyxia is one of the three most important causes of neonatal mortality and morbidity [1]. It is a major contributor to long term neurodevelopmental sequele in the developing world. During fetal hypoxia-ischemia, ‘diving reflex’ shunts blood from ‘non-vital areas’ such as skin and splanchnic circulation to the ‘vital organs’ like heart, adrenals, and brain to protect them from injury. Thus theoretically, any newborn with neurological injury due to asphyxia should also have derangements of the ‘non-vital organs’ like kidney and gut. However, even in cases of severe intrapartum asphyxia, the involvement of various organs is not consistent and ranges from 70 to 100 % [2, 3]. There could be multiple reasons behind this variation: (a) all organs may not be equally involved due to variable activation of ‘diving reflex’ [4], (b) use of different criteria to define multi-organ dysfunction (MOD) and asphyxia, and (c) variable timing of clinical and laboratory evaluation. The American Congress of Obstetricians and Gynecologists (ACOG) uses MOD as one of the contributory rather than essential criteria to determine the intrapartum timing of insult [5]. Although renal, cardiac, pulmonary, hepatic and gastrointestinal systems could all be affected by perinatal asphyxia, heart and kidneys are the two most important extra-cerebral organs involved. The incidence of renal injury is 50–72 % while cardiac injury has been seen in 29–78 % in various studies. Damage to these organs can be persistent and may predict outcomes [6]. Renal injury in neonatal encephalopathy is associated with more severe brain injury and adverse longterm neurodevelopmental outcome [7]. Hence, it is important to be able to make an early and reliable diagnosis of hypoxicischemic injury to these organs. Cardiac injury has been diagnosed on the basis of clinical grounds, echocardiography, electrocardiography (ECG) and elevation of cardiac enzymes. Echocardiography is most commonly used to assess myocardial dysfunction though Ctroponin-T has emerged as a marker having good correlation with severity and outcome. ECG criteria for cardiac injury in perinatal asphyxia have been described but are cumbersome to apply [8]. Moreover, there are technical difficulties in recording and interpreting ECGs in sick newborns. Traditionally, ECG criteria have used T/QRS ratio and changes in ST segment to evaluate myocardial ischemia in asphyxiated newborns. P-wave dispersion has been used to evaluate the discontinuous propagation of sinus impulse and predict atrial fibrillation in adult patients with anterior wall myocardial infarction [9]. The incidence of atrial fibrillation secondary to intrapartum asphyxia in the newborn is, however, not known. In this issue of the journal, Amoozgar et al. have attempted to understand the changes in P-wave dispersion in asphyxiated neonates [10]. They have also attempted to relate P-wave dispersion with severity of asphyxia, arrhythmias, Apgar scores and C-Troponin I. The research idea is novel as the effects of perinatal asphyxia on cardiac conduction system are not well described. Unfortunately, because of several flaws in design, methodology and analysis, reliable conclusions cannot be drawn from this study. It is not clear if all 4 of the listed criteria had to be met or any one was good enough for a diagnosis of asphyxia. The inclusion criteria for controls mention the requirement of a normal neurological examination at birth and first week. The ECGs were however recorded on day 3. It is not clear if and how many of the ‘enrolled’ infants were subsequently excluded. The authors chose a snapshot window on day 3 of life to look at the ECGs. However, the changes in the ECG are dynamic and may be A. Bhatti Department of Pediatrics, Government Medical College, Jammu, India

P-wave dispersion and its relationship with the severity of the disease in patients with stable coronary artery disease.

OBJECTIVE:P- wave dispersion (PD) is an indicator of inhomogeneous and discontinuous propagation of sinus impulses. In the present study we aimed to investigate the PD and its association with the severity of the disease. in patients with stable coronary artery disease.METHODS:We prospectively analyzed 60 subjects with coronary artery disease (CAD) and 25 subjects with nor-mal coronary angiograms (control group). The maximum and minimum P-wave duration and PD were measured from the 12-lead surface electrocardiograms. The CAD severity was assessed by the severity score (Gensini score) and the number of vessels involved (vessel score).RESULTS:P max was longer in CAD group compared with the control group (p<0.001). PD was greater in the CAD group, compared with the control group (p<0.001). However, P min did not differ between the two groups. In bi-variate correlation, increased PD was correlated with presence of diabetes mellitus (r=0.316, p=0.014), smoking (r=0.348, p=0.006), left ventricular ejection fraction (r=-0.372, p=0.003), vessel score (r=0.848, p=0.001), and Gensini score (r=0.825, p=0.001). Multiple linear regression analysis showed that PD was independently associ¬ated with vessel score ((3=0.139, p=0.002) and Gensini score ((3=0.132, p=0.007).CONCLUSION:PD was greater in patients with CAD than in controls and it was associated with CAD severity.

The effect of nebivolol on P wave duration and dispersion in patients with Behçet’s disease; a prospective single-arm controlled study

Behçet's disease (BD) is a chronic multi-system disease presenting with recurrent oral and genital ulceration, and relapsing uveitis. Left ventricular diastolic dysfunction, ventricular arrhythmia and sudden cardiac death have been documented in BD. P wave dispersion (PD) has been reported to be associated with inhomogeneous and discontinuous propagation of sinus impulses. PD has been reported to be longer in patients with BD. Nebivolol, besides its selective beta1-blocking activity, causes an endothelium dependent vasodilatation through nitric oxide release. In this study, we searched for the effects of nebivolol on P wave duration and dispersion in patients with BD. This study was designed as prospective single-arm controlled study. We prospectively studied 35 Behçet's patients who were diagnosed according to the International Study Group criteria. Patients received 5 mg nebivolol per day for 3 months. The patients were evaluated with 12-leads electrocardiography at baseline and after for 3-month therapy. The difference between maximum and minimum P wave durations was defined as PD. The paired samples t test, Wilcoxon test were used for statistical analysis. A significant decrease was observed in PD after therapy period (62.85±21.62 vs. 44.28±18.03 msec, p=0.001). No adverse effects were observed in treatment period. BD is associated with prolonged P wave duration and dispersion. We have shown for the first time that nebivolol causes a significant decrease in maximum P wave duration and PD in patients with BD. However, further comprehensive studies are needed to determine the long-term effects of nebivolol.

Assessment of Atrial Conduction Abnormalities in Patients with Hypertrophic Cardiomyopathy Before and One Year after Alcohol Septal Ablation

Objectives: Intra- and interatrial electromechanical delay (AEMD) can be used to evaluate the development of atrial fibrillation (AF). Percutaneous transluminal septal myocardial ablation (PTSMA) is an alternative therapy for patients with hypertrophic obstructive cardiomyopathy (HOCM) that results in sustained improvements in atrial structure and function. We investigated the effects of PTSMA on the intra- and inter-AEMD of HOCM patients using tissue Doppler imaging. Methods: Conventional echocardiographic and AEMD parameters were obtained in 25 healthy controls and 31 HOCM patients before and 1 year after septal ablation procedures. Results: Compared with the healthy controls, the left atrial volumes indexed by body surface area (LAVI) and the intra- and inter-AEMD were significantly higher in the HOCM patients. At 1 year after PTSMA, the LAVI was decreased (37.2 ± 11.4 to 27.0 ± 8.5 ml/m², p < 0.001). The intra- and inter-AEMD were also significantly decreased (22.7 ± 9.2 to 16.6 ± 7.7 ms, p < 0.001 and 37.0 ± 8.4 to 26.6 ± 8.0 ms, p < 0.001, respectively). These changes correlated well with the reductions in LAVI (r = 0.83, p < 0.001; r = 0.66, p < 0.001). Conclusions: Both the intra- and inter-AEMD were significantly prolonged in the HOCM patients. PTSMA can improve the prolonged and inhomogeneous propagation of sinus impulses in atria.

Importance of P-Wave Indices in a Sample of Iraqi Type 2 Diabetic Patients

Background: Diabetes mellitus has a negative impact on the cardiovascular system; P-wave indices were considered to reflect the discontinuous and inhomogeneous propagation of sinus impulses and prolongation of atrial conduction time. Objectives: to know importance of P-wave indices and significant of its use for prediction and evaluation of diabetic complication in type 2 diabetics. Methods and Results: A case control study, Dec. 2011, on diabetics (n=88) and healthy relatives (n= 70) were conducted in the NDC. Comparing both groups for age, sex, resting heart rate and BMI revealed insignificant differences, P > 0.05. P-wave indices of diabetics shown absence of any correlation with the age, duration of diabetes, FPG, BMI, resting heart rate and HDL; But, it shown weak correlation with HbA1c, Serum cholesterol, serum triglycerides and LDL. P-wave indices show significant higher values in diabetics than in healthy subjects, P 0.05. Conclusions: P-wave indices (Pmean, Pmax, and Pd) were significantly higher in diabetics than the healthy individuals. P-wave indices of diabetics have no effect on gender, age and BMI; but, have weak correlation with HbA1c, Serum cholesterol, serum triglycerides and LDL.

Quantification of not-dipolar components of atrial depolarization by principal component analysis of the P-wave

Principal component analysis (PCA) of the T-wave has been demonstrated to quantify the dipolar and not-dipolar components of the ventricular activation, the latter reflecting repolarization heterogeneity. Accordingly, the PCA of the P-wave could help in analyzing the heterogeneous propagation of sinus impulses in the atria, which seems to predispose to fibrillation. The aim of this study is to perform the PCA of the P-wave in patients prone to atrial fibrillation (AF). PCA is performed on P-waves extracted by averaging technique from ECG recordings acquired using a 32-lead mapping system (2048 Hz, 24 bit, 0-400 Hz bandwidth). We extracted PCA parameters related to the dipolar and not dipolar components of the P-wave using the first 3 eigenvalues and the cumulative percent of variance explained by the first 3 PCs (explained variance EV). We found that the EV associated to the low risk patients is higher than that associated to the high risk patients, and that, correspondingly, the first eigenvalue is significantly lower while the second one is significantly higher in the high risk patients respect to the low risk group. Factor loadings showed that on average all leads contribute to the first principal component.

P-Wave Dispersion in Children With Acute Rheumatic Fever

As a new and simple electrocardiographic marker, P-wave dispersion is reported to be associated with inhomogeneous and discontinuous propagation of sinus impulses. The current study aimed to investigate P-wave dispersion in children with acute rheumatic fever. The study population consisted of 47 children with acute rheumatic fever (29 patients with carditis and 18 patients without carditis) and 31 healthy control subjects. Maximum and minimum P-wave durations were measured from the 12-lead surface electrocardiogram. The P-wave dispersion was calculated as the difference between maximum and minimum P-wave durations. The maximum P-wave duration and the P-wave dispersion of the patients with and without carditis were significantly greater than those of the control subjects. The P-wave dispersion of the patients with carditis was significantly greater than that of the patients without carditis. In conclusion, the P-wave dispersion was higher in the children with acute rheumatic fever than in the healthy control subjects.

P wave and QT changes among inpatients with schizophrenia after parenteral ziprasidone administration

Objective Although ziprasidone has been reported to cause ventricular arrhythmias, there have been no studies regarding the influence of ziprasidone on atrial conduction. Intraatrial and interatrial conduction time prolongation and inhomogeneous propagation of sinus impulses are indicated by P wave changes on surface electrocardiography. We aimed to evaluate proneness to atrial fibrillation after intramuscular ziprasidone in drug-free inpatients with schizophrenia. Methods We evaluated 11 eligible inpatients who were drug free for at least 4 weeks with a primary diagnosis of schizophrenia disorder and 11 healthy controls who were hospital staff members. Electrocardiography was performed at baseline and 1.5–2 h after ziprasidone injection. A 12-lead surface electrocardiogram was obtained from each subject in the supine position at a paper speed of 50 mm/s and 2 mV/cm. Results The changes between baseline and the period after parenteral ziprasidone administration in P-wave duration, P-wave dispersion, QTc, QTc max, QTc min, and QT dispersion variables were significant ( p > 0.05). The initial P-wave dispersion was significantly longer in patients than in healthy controls ( p < 0.05). There were no correlations between electrocardiography parameters and clinical severity scores or demographic variables in either group. Conclusion Intramuscular ziprasidone administration does not seem to influence atrial and ventricular electrical conduction in drug-free inpatients with schizophrenia. However, schizophrenia might affect atrial conduction resulting in atrial fibrillation, which may be a cause of some complications in inpatients with this schizophrenia.

Association of P wave duration and dispersion with the risk for atrial fibrillation: Practical considerations in the setting of coronary artery disease

P wave dispersion (PWD) is defined as the difference between maximum P wave duration (Pmax) and minimum P wave duration recorded from multiple surface electrocardiogram (ECG) leads. An increase in PWD indicates heterogeneous intraatrial and interatrial conduction and discontinuous anisotropic propagation of sinus impulses, providing a substrate that favors reentry mechanisms. Prolonged Pmax and increased PWD have been suggested to represent independent predictors for atrial fibrillation (AF). The distinctive atrial electrophysiological peculiarity featured by slow interrupted propagation of atrial impulses could be reflected by an increase in PWD predisposing to AF. Coronary artery disease (CAD) is also a well-known risk factor for AF. There are some potential mediators between CAD and AF. The noninvasive nature of P wave duration and PWD with their comparative simplicity makes these parameters attractive options; however, standards involving precise assessment are still lacking. Further exploration of the exact determinants for P wave duration and PWD would help establish the practical usefulness of these surface ECG markers in estimating the risk for AF occurrence and recurrence.

The effects of surgical repair on P-wave dispersion in children with secundum atrial septal defect

Atrial septal defect (ASD) is one of the most common congenital heart diseases in children. P-wave dispersion has been reported to be associated with non-homogeneous propagation of sinus impulses. The heterogeneity of atrial conduction time may predispose the atria to arrhythmias. The aim of this study was to determine the impact of surgical repair on P-wave indices in children with isolated secundum ASD. Children with isolated secundum ASD undergoing surgical repair (n=50; mean age, 7.0+/-3.0 years) and healthy controls (n=51; mean age, 7.6+/-2.7 years) were compared. Maximum P-wave duration (Pmax), shortest duration (Pmin) and P-wave dispersion (Pd) were measured using 12-lead surface electrocardiography. Mean Pmax was found to be significantly higher in children with ASD compared with controls (95.2+/-10.8 vs 84.1+/-9.2 msec; P<0.001), and Pd before surgery was significantly higher compared with controls (47.4+/-12.0 vs 38.8+/-9.7 msec; P<0.001). Both P-wave indices were significantly decreased within the first year after surgical closure - the values decreased to those comparable to healthy controls (Pmax, 86.2+/-9.7 msec; Pd, 39.8+/-10.7 msec; P>0.05). Surgical closure of ASD in children decreases Pmax and P-wave conduction time. We speculate that earlier closure of the defect may play an important role in avoiding permanent changes in the atrial myocardium and atrial fibrillation in adulthood.