Introduction: The main component of the endocardial acceleration signal (SonR) is today used for cardiac resynchronization therapy (CRT) optimization. This prospective, single center pilot study focuses on another signal component, SonR4 that may provide further information on the atrial activity. Methods and Results: SonR signal and ECG tracings were recorded simultaneously during a CRT-D optimization procedure in 15 patients (12 men, 68 ± 9.5 years, ischemic heart disease 53%) indicated for CRT. Correlation between SonR4 signal, recorded using SonR and atrial con- traction, identified by Echo Doppler was evaluated by Pearson and Student’s t tests under differ- ent Atrio-Ventricular (AV) delay programming. From 15 consecutive screened patients, 9 had concomitant analyzable SonR4 and ECG recordings and were included in the study population. The presence of the SonR4 component was systematically correlated to the presence of the A wave. A significant correlation was observed between SonR4 and A wave timings (r = 0.75, p = 0.02) ac- cording to different AV delays, with a high reproducibility in SonR4 assessment. Conclusion: A strong correlation between SonR4 and atrialcontraction timings was observed, further suggesting that SonR4 is a marker of the atrialcontraction. Additional assessments in larger populations are required to confirm these results and build further applications.
Ventricular filling may occur directly from the venous circulation during early diastole or via atrialcontraction in late diastole. The contribution of atrialcontraction to ventricular filling is typically small in mammals (10 – 40%), but has been suggested to predominate in reptiles. We investigated the importance of atrialcontraction in filling of the ventricle in American alligators (Alligator mississippiensis) by bypassing both atria (with the use of ligatures to prevent atrial filling) and measuring the resultant effects on cardiac output in anesthetized animals. Atrial ligation had no significant effects on total systemic blood flow before or after adrenaline injection. Unexpectedly, pulmonary flow was increased following atrial ligation prior to adrenaline treatment, but was unaffected after it. These findings suggest that the atria are non-essential (i.e. redundant) for ventricular filling in alligators, at least under anesthesia, but may serve as important volume reservoirs.
An interesting finding is that depression of atrial con- traction force occurs prior to the bradycardic response. Almost 80% of the atrial force can be inhibited before CCh's effect on HR starts to appear, i.e. under weak and moderate cholinergic tone atrialcontraction is strongly depressed without changes in HR. Similar dichotomy between inotropic and chronotropic effects of cholinergic activation has been noted in the tilapia (Orechormis nilot- ica/aureus) heart . The dissociation of inotropic and chronotropic responses to muscarinic activation proba- bly provides a finely tuned mechanism to regulate cardiac output first by reducing end-diastolic filling of the ventri- cle via weakened atrialcontraction and then via depres- sion of contraction frequency.
views. Mitral inflow velocities were evaluated by pulsed wave (PW) Doppler echocardiography with the sample volume placed at the tip of the mitral leaflets from the apical four-chamber view. Diastolic fillings were classified initially on the basis of the peak mitral flow velocity of the early rapid filling wave (E), peak velocity of the late filling wave caused by atrialcontraction (A), E/A ratio, and deceleration time (DT), which is the time interval for the peak E velocity to reach zero baseline. Mitral inflow velocities were evaluated by pulsed wave (PW) Doppler echocardiography with the sample volume placed at the tip of the mitral leaflets from the apical four-chamber view. The LV cavity elongates, rotates, and expands laterally after myocardial relaxation. The longitudinal motion of the mitral annulus has been shown to correlate with the rate of myocardial relaxation. 15
In order to evaluate the effects of atrialcontraction on left ventricular function, the pressure gradient technique was used to measure instantaneous aortic blood flow and pressure in nine patients, six having complete heart block and three having normal sinus rhythm. From these data both left ventricular stroke volume and stroke work were calculated. Ventricular rate was controlled by transvenous right ventricular pacing over a range of 50-158
The effect of atrialcontraction on left ventricular function in six patients with varying degrees of mitral stenosis was determined by utilizing the pressure gradient technique to measure instantaneous aortic blood flow and pressure. Aortic flow was measured as ventricular rate was controlled by right ventricular pacing to create A-V (atrioventricular) dissociation at varying rates (90-150 beats/min). At each heart rate, beats with preceding P waves, effective atrial systole, were grouped according to the duration of the P-R interval. Beats without P waves served as controls. There was always a significant increase in stroke volume,
also found in a previous study. Although 2-D-derived variables measure volumes and volume-derived indices that might indicate some kind of atrial mechanical force, it was surprising to find no correlations between the vari- ables obtained by the two different techniques. This might indicate that the velocities and the displacements regis- tered from all atrial walls by TVE are less dependent on volume loading conditions than 2-D-derived variables and therefore could be used as reliable measurement of pure atrial mechanical contraction or inotropism. In fact, Donald et al. showed that LA function assessed by TVE was relatively independent of LV function. It should also be considered that movements of the heart not related to atrialcontraction might partly contribute to the velocities and displacements registered from all atrial walls. Therefore, 2-D- and TVE-derived variables might
associated with a low percentage of structural abnormalities in 2 % of cases. It is defined by a 1:1 atrioventricular conduction in which the atrialcontraction precedes the ventricular contraction. Heart rates in SVT most commonly range from 200-300 bpm, is either paroxysmal or incessant in nature and associated with fetal hydrops in 36 - 64 % 14,33 . The condition has
In this paper we are going to introduce the concept of sequentially weak contraction using sequence of function which is uniformly convergent to a continuous function . The concept of sequence of function is already given by Dutta et. al..
Left ventricular diastolic function was assessed by meas- uring the mitral flow velocity recorded in the apical four-- chamber view. The pulse Doppler sample volume was placed in the left ventricular inflow tract at the level of mi- tral leaflet tips and three consecutive measurements were averaged. The various variables of diastolic function that were measured included: peak early (E; m/sec) and peak atrial filling velocity (A; m/s), ratio of E to A (E/A), E ac- celeration time, E deceleration time (Edt; m/s), isovolumic relaxation time (IVRT) was measured in the apical five chamber view with the sample volume placed between the aorta and mitral valve where the recordings of both valves were taken simultaneously.
Even though it is agreed that no single current echocardiographic measure is sufficient for a diagnosis of LV diastolic dysfunction, the use of algorithms of many different echocardiographic parameters is also problematic as a situation of “one size fits all” arises. Additionally, the fundamental use of velocity based parameters in these algorithms is deficient as the use of velocities as a determinant of diastolic function only takes one snapshot of imaging into consideration, thereby making an accurate depiction of severity difficult to obtain, especially in patients with atrial fibrillation. Lastly, the echocardiographic parameters used in these algorithms are only estimates of LV filling pressures and are subject to limitations of the imaging technique, such as angle dependency, sample volume, and tethering arti- facts as well as to shortcomings inherent to derivation of pressures from inflow or re-extension signals .
Atrial Fibrillation (AF) is the most prevalent arrhythmia occurring especially in the elderly. The extremely dire complication of this condition is cardiac thromboembolism that commonly arises from the Left Atrial Appendage (LAA) and may lead to stroke. Currently, guidelines recommend Oral Anticoagulants (OACs) as the therapy of choice for AF patients who are considered susceptible to develop stroke. Although, OACs have been proven effective for this purpose, they are not always an appropriate choice as they increase the likelihood of major bleeding, which can be specifically problematic to patients who for any reason, already have a moderate to high risk for bleeding. Moreover, the need for frequent PT, PTT and INR assessments and patients’ non-compliance can add to the problems of long-term use of OACs. The search for alternative treatment choices has resulted in the evolution of Percutaneous Left Atrial Appendage Closure (LAAC). Multiple devices have been developed to be applied to this method, the most well-studied of which is the Watchman device. At the moment, percutaneous LAAC is being recommended only by European guidelines and just for patients with non-valvular AF (NVAF) who have a high potential for stroke and who are contraindicated to OAC therapy. The method still offers several challenges and requires more evidence to be approved as a definitive treatment option. In this article, we reviewed the concept behind LAAC and its indications, the available evidence on safety and effectiveness of LAAC with Watchman and focused on the challenges underlying this developing therapy.
We now give a simple condition in terms of metric transforms which implies that a map- ping g : X → X is a local radial contraction. Notice that if φ is taken to be the identity mapping, the following result reduces to the deﬁnition of a local radial contraction. Theorem . Let (X, d) be a metric space and g : X → X. Suppose there exists a metric transform φ on X and a number k ∈ (, ) such that the following conditions hold:
underwent a comprehensive transthoracic echocardiographic examination to assess LA size and function, left ventricular (LV) function, and to exclude structural heart disease. In addition, a novel echocardiographic parameter was assessed to estimate the total atrial conduction time (PA-TDI duration). The PA- TDI duration is measured using TDI during sinus rhythm. Therefore, patients who were in atrial fibrillation during echocardiography were excluded from the analysis. After the ablation, all patients were evaluated on a systematic basis at the outpatient clinic during a 12 months follow-up period. Electrocardiogram (ECG) recordings were acquired each visit and 24-hour Holter registrations were scheduled after 3, 6 and 12 months follow-up. Importantly, all patients were encouraged to immediately obtain an ECG registration when experiencing palpitations. All medications were continued for at least 3 months. Afterwards, anti-arrhythmic drugs were discontinued at the discretion of the physician. After a blanking period of 3 months, recurrence of AF was defined as any recording of AF on ECG or an episode longer than 30 s on 24- hour Holter registration.
depolarization and the initiation of AF. As a result of the impact, the atrial tissue may exhibit a dispersion of refractoriness inducing a so-called heterogeneity of atrial repolarization, which can perpetuate and sustain AF. Although AF was not studied or induced in animal models of low- energy chest wall impact, and AF was not documented in young athletes related to chest trauma, there is a case report in an adult that proposes the association of a fall injury with AF. 13 It is possible that
Abstract: Objective: Fibroblast growth factor-21 (FGF-21) has been discovered as a strong hormone, plays an im- portant role in lipid metabolism, glucose metabolism, associated with several diseases such as obesity, metabolic syndrome, diabetes mellitus, and cardiovascular events; however, no evidence is available concerning the relation- ship of FGF-21 and atrial fibrosis in patients with atrial fibrillation (AF) and rheumatic heart disease (RHD). Methods: Twenty-four rheumatic heart disease patients were divided into two groups, 12 cases with AF and 12 cases with sinus rhythm (SR). Clinical characteristics and blood samples were collected before surgery; right atrial appendage samples were taken in the surgery of valve replacement. HE staining was performed to determine cross-sectional area of atrial myocytes; Masson stained sections and mRNA levels of cardiac fibrosis biomarkers were used to evaluate the degree of cardiac fibrosis; the level of FGF-21 was evaluated via enzyme-linked immunosorbent assay (ELISA), immunohistochemistry, and real-time polymerase chain reaction (PCR). Results: Compared with SR group, cross-sectional area of atrial myocytes and collagen volume fraction were significantly increased in the atrial tissue of AF group. The distribution of FGF-21 in the AF group was remarkably higher than SR group. In addition, plasma and mRNA levels of FGF-21 in atrial tissue of AF showed the same trend as the result of immunohistochemistry. Using linear correlation analysis, the expression level of FGF-21 was found to be positively related to the degree of atrial fibrosis. Conclusion: FGF-21 might involve in the development and maintenance of atrial fibrosis in atrial fibrillation with rheumatic heart disease, and FGF-21 could be used as a novel biomarker to evaluate myocardial fibrosis in the future.
are the generalization of commuting maps. Jungck (Jungck, 1986) enlarged this concept of weakly commutativity by introducing compatible maps. In (Berinde, 2010), Vasile Berinde obtained coincidence and common fixed point theorems, similar to the one in (Abbas and Jungck, 2008), but for more general class of almost contraction, by restricting the ambient space to the class of usual metric spaces. In (Bakhtin, 1989), Bakhtin introduced b-metric space as a generalization of metric spaces and proved a contraction mapping principle in b-metric space that generalized the famous Banach contraction principle in metric spaces. In 2011, Hussain and Shah (Hussain and Shah, 2011) introduced cone b-metric spaces as a generalization of b-metric spaces and cone metric spaces. Recently, Huang and Xu (Huang and Xu, 2012) have proved some fixed point theorems of contraction mapping without the assumption of normality condition in complete cone b-metric space. Inspired and motivated by a result mentioned on (Berinde, 2010) and using the notion introduced on (Shi and Xu, 2013) and (Huang and Xu, 2012), the purpose of the research is to study existence and uniqueness of coincidence point and common fixed point results for a large class of almost contraction in complete cone b-metric space.