Giant left atrial appendage

A 42-year-old man was evaluated at our hospital because of paroxysmal atrial fibrillation. Physical examination and ECG during sinus rhythm were unremarkable (no signs of left atrial enlargement).     

IDENTIFICATION OF LARGE LEFT ATRIAL THROMBUS BY CROSS-SECTIONAL AND M-MODE ECHOCARDIOGRAPHY

In addition to a typical pattern indicative of mitral stenosis, the M-mode echo-cardiogram of a patient with mitral valve disease revealed a broad band of dense echoes within an enlarged left atrial cavity that was suggestive of an intraatrial thrombus. Subsequent cross-sectional echocardiography demonstrated a globular cluster of echoes inside the left atrial cavity, thus corroborating our interpretation of the M-mode recording. When open mitral commissurotomy was performed, a large, partially calcified thrombus was found protruding from the posterior wall and left atrial appendage into the atrial cavity. Postoperative M-mode and cross-sectional echocardiography did not show the previously noted abnormal echoes within the left atrium.     

The physiology of atrial natriuretic factor

Following the discovery of the natriuretic effect of atrial extract, our laboratory attempted to dissect the possible physiological role of atrial natriuretic factor. Initial micropuncture experiments demonstrated that the reduction of tubular sodium reabsorption was localized in the medullary collecting duct, a nephron site in which sodium transport was known to be inhibited after acute hypervolemia. Partial removal of the endogenous source of atrial natriuretic factor was associated with a reduced renal response to hypervolemia, confirming that the factor is causally involved in acute sodium balance. In vitro incubation of atrial tissue was used to investigate mechanisms of release of atrial natriuretic factor. It was found that agonists known to activate the intracellular polyphosphoinositide system in other tissues were effective in releasing natriuretic activity from the atria into the incubation medium. To determine whether atrial natriuretic factor might play a role in hypertension, atrial natriuretic content was measured in spontaneously hypertensive rats and their normotensive controls. Hypertension was associated with increased content. Since the renal response to exogenous factor was not impaired in these animals, we suggested that the increased content might play a compensatory role. Our early studies thus indicated that atrial natriuretic factor was a previously unrecognized hormone involved in cardiovascular regulation.     

Echocardiographic [correction of Ehocardiographic] evaluation of regional left atrial function after rapid atrial pacing

Rapid regular atrial pacing (RAP) produces changes in atrial function similar to those caused by atrial fibrillation in animal models. Left atrial appendage (LAA) function represents regional atrial function. The aim of our study was to investigate the influence of RAP on left atrial regional function and to evaluate the reversibility of changes after termination of pacing in a canine model. Eight dogs were subjected to RAP (400 bpm) for 16 days. Transesophageal echocardiography was performed at baseline, immediately after RAP and 4 weeks after the termination of RAP. The LAA peak late emptying velocity (LAA-E) and filling wave (LAA-f) were measured. LAA-E velocities were significantly reduced and filling wave velocities (LAA-f) were significantly less negative after RAP compared with the baseline values. Four weeks after termination of pacing, the LAA-E and LAA-f velocities were normal. RAP results in impaired regional atrial systolic and diastolic function. The changes were completely reversible 4 weeks after termination of pacing. These results suggest that the LAA is mechanically stunned after RAP.     

Electrophysiological Features of Atrial Flutter in Cardiac Sarcoidosis: A Report of Two Cases

We report two cases of systemic sarcoidosis with atrial flutter as the clinical manifestation. In one patient, who had symptoms of shorter duration, the arrhythmia was no longer inducible after a course of glucocorticoid therapy. Electroanatomical mapping in the other case revealed patchy fibrosis of the left atrial myocardium and multiple macro-reentrant circuits. Sinus rhythm could be restored with ablation of these reentrant circuits. To our knowledge, this is the first report on the demonstration of atrial scarring in a patient with sarcoidosis using 3-D electroanatomical mapping. These two cases illustrate that the inflammation of atrial myocardium is the primary mechanism of atrial arrhythmias in patients with cardiac sarcoidosis.     

Catheter ablation of atrial incisional tachycardia mistaken for atrial flutter

Incisional sustained tachycardias are frequent in patients who have undergone a surgical repair of interatrial defect. A 43-year-old woman with drug refractory, highly symptomatic, persistent atrial tachycardia in the last year, was referred to our unit for catheter ablation. The patient had undergone a cardiac operation for repairing interatrial secundum ostium type defect with a patch five years before. A previous radiofrequency ablation procedure had been performed for common atrial flutter. We describe a case of incisional atrial tachycardia ablation guided by the new EnSite NavX system equipped with a new electroanatomic mapping system.     

Successful cryoablation of an incessant atrial tachycardia arising from the right atrial appendage

The right atrial appendage can be the origin of focal atrial tachycardias. Their ablation can be challenging owing to the complexity of the appendage anatomy. To our knowledge, we describe the first successful solid tip cryoablation of a focal tachycardia within the right atrial appendage in a patient presenting with tachycardia-induced cardiomyopathy.     

心力衰竭合并房颤患者血浆脑钠肽水平及相关因素分析

目的:探讨心力衰竭合并房颤患者血浆脑钠肽水平变化及相关因素,为心血管疾病的临床诊断提供理论依据。方法:选取我院2011年1月-2013年1月收治的心力衰竭患者94例,分为窦性心律组和心房颤动组。分别抽取两组患者的血液样本并检测血浆中的BNP浓度,比较不同NYHA分级患者血浆内的脑钠肽水平的变化情况,记录左心房和左心室舒张末内径及房颤持续时间等。结果:心力衰竭合并心房颤动组与窦性心律组血浆BNP水平比较,心房颤动组高于窦性心律组;差异有统计学意义(P0.05);两组NYHA不同分级相互比较,Ⅱ级、Ⅲ级和Ⅳ级间的BNP水平,心房颤动组BNP水平均高于窦性心律组;差异显著具有统计学意义(P0.05);血浆BNP水平与患者年龄、左心房大小、左心室大小、房颤持续时间因素呈正相关(r分别为0.0.801,0.748,0.854和0.703,P0.05),与左心室射血分数呈负相关(r=-0.41,P0.05)。结论:BNP血浆浓度与心功能状态密切相关,BNP浓度的检测有助于临床心血管疾病的诊断。     

Protective mechanism of SIRT1 on Hcy‐induced atrial fibrosis mediated by TRPC3

High plasma levels of homocysteine (Hcy) are regarded as a risk factor for atrial fibrillation (AF), which is closely associated with the pathological consequence of atrial fibrosis and can lead to heart failure with a high mortality rate; here, we show that atrial fibrosis is mediated by the relationship between canonical transient receptor potential 3 (TRPC3) channels and sirtuin type 1 (SIRT1) under the stimulation of Hcy. The left atrial appendage was obtained from patients with either sinus rhythm (SR) or AF and used to evaluate the relationship between the concentration of Hcy and a potential mechanism of cardiac fibrosis mediated by TRPC3 and SIRT1. We next performed transverse aortic constriction (TAC) in mouse to investigate the relationship. The mechanisms underlying atrial fibrosis involving TRPC3 and SIRT1 proteins were explored by co‐IP, BLI and lentivirus transfection experiments. qPCR and WB were performed to analyse gene and protein expression, respectively. The higher level of atrial fibrosis was observed in the HH mouse group with a high Hcy diet. Such results suggest that AF patients may be more susceptible to atrial fibrosis and possess a high probability of progressing to hyperhomocysteinemia. Moreover, our findings are consistent with the hypothesis that TRPC3 channel up‐regulation leads to abnormal accumulation of collagen, with the down‐regulation of SIRT1 as an aetiological factor of high Hcy, which in turn predisposes to atrial fibrosis and strongly enhances the possibility of AF.     

Distinct Patterns of Constitutive Phosphodiesterase Activity in Mouse Sinoatrial Node and Atrial Myocardium

Phosphodiesterases (PDEs) are critical regulators of cyclic nucleotides in the heart. In ventricular myocytes, the L-type Ca²⁺ current (I_Ca,L) is a major target of regulation by PDEs, particularly members of the PDE2, PDE3 and PDE4 families. Conversely, much less is known about the roles of PDE2, PDE3 and PDE4 in the regulation of action potential (AP) properties and I_Ca,L in the sinoatrial node (SAN) and the atrial myocardium, especially in mice. Thus, the purpose of our study was to measure the effects of global PDE inhibition with Isobutyl-1-methylxanthine (IBMX) and selective inhibitors of PDE2, PDE3 and PDE4 on AP properties in isolated mouse SAN and right atrial myocytes. We also measured the effects of these inhibitors on I_Ca,L in SAN and atrial myocytes in comparison to ventricular myocytes. Our data demonstrate that IBMX markedly increases spontaneous AP frequency in SAN myocytes and AP duration in atrial myocytes. Spontaneous AP firing in SAN myocytes was also increased by the PDE2 inhibitor erythro-9-[2-hydroxy-3-nonyl] adenine (EHNA), the PDE3 inhibitor milrinone (Mil) and the PDE4 inhibitor rolipram (Rol). In contrast, atrial AP duration was increased by EHNA and Rol, but not by Mil. IBMX also potently, and similarly, increased I_Ca,L in SAN, atrial and ventricular myocytes; however, important differences emerged in terms of which inhibitors could modulate I_Ca,L in each myocyte type. Consistent with our AP measurements, EHNA, Mil and Rol each increased I_Ca,L in SAN myocytes. Also, EHNA and Rol, but not Mil, increased atrial I_Ca,L. In complete contrast, no selective PDE inhibitors increased I_Ca,L in ventricular myocytes when given alone. Thus, our data show that the effects of selective PDE2, PDE3 and PDE4 inhibitors are distinct in the different regions of the myocardium indicating important differences in how each PDE family constitutively regulates ion channel function in the SAN, atrial and ventricular myocardium.     

Atrial gland induction of the egg-laying response inAplysia californica

Summary The atrial gland of the large hermaphroditic duct of the reproductive tract ofAplysia californica contains a substance that will cause egg laying when injected into sexually mature recipient animals. Preliminary chemical characterization of the atrial gland factor indicates that it is quite similar to the egg-laying hormone synthesized and secreted by the bag cell neuroendocrine organs of the central nervous system. In view of the apparent identity of its effects with those of the egg-laying hormone on presumed neural and reproductive system targets, it is possible that the atrial gland factor plays an hitherto unsuspected role in reproductive regulation. Moreover, the molecular similarity between the atrial gland factor and the egg-laying hormone suggests the possibility that the same humorally active species may be elaborated by two distinct tissue types.This work was supported by grants from the Medical Research Foundation of Oregon and USPHS (NS 11149). C. McC. was recipient of a Zlinkoff Research Fellowship. Dr. R. Beeman kindly confirmed our identification of the location and general morphology of the atrial gland.     

Atrial fibrillation and delayed gastric emptying

Background

Atrial fibrillation and delayed gastric emptying (DGE) are common after pancreaticoduodenectomy. Our aim was to investigate a potential relationship between atrial fibrillation and DGE, which we defined as failure to tolerate a regular diet by the 7^th postoperative day.

Methods

We performed a retrospective chart review of 249 patients who underwent pancreaticoduodenectomy at our institution between 2000 and 2009. Data was analyzed with Fisher exact test for categorical variables and Mann-Whitney U or unpaired T-test for continuous variables.

Results

Approximately 5% of the 249 patients included in the analysis experienced at least one episode of postoperative atrial fibrillation. Median age of patients with atrial fibrillation was 74 years, compared with 66 years in patients without atrial fibrillation (p = 0.0005). Patients with atrial fibrillation were more likely to have a history of atrial fibrillation (p = 0.03). 92% of the patients with atrial fibrillation suffered from DGE, compared to 46% of patients without atrial fibrillation (p = 0.0007). This association held true when controlling for age.

Conclusion

Patients with postoperative atrial fibrillation are more likely to experience delayed gastric emptying. Interventions to manage delayed gastric function might be prudent in patients at high risk for postoperative atrial fibrillation.     

Intermittent Right Ventricular Outflow Tract Capture due to Chronic Right Atrial Lead Dislodgement

A 58 year old male, known case of type 2 diabetes and hypertension, had undergone implantation of a dual chamber pacemaker(DDDR) in 2007 for complaints of recurrent syncope and trifascicular block with a normal ejection fraction andnormal coronaries. His post implantation parameters were normal at that time.He now presented to our pacemaker clinic where his ECG done showed two types o fpaced complexes. The first few complexes were consistent with atrial sensed right ventricular apical pacing with left superior axis. Later complexes showed loss of atrial sensing with pacing from right ventricular outflow tract(inferior axis) with subtle oscillation in it''s axis. On application of magnet, two pacemaker spikes were visible withinterspike interval of 120 ms and paced complexes with inferior axis starting from the first spike suggesting that the atrial lead was responsible for RVOT depolarization. On interrogation of the pacemaker, atrial EGM showed sensed activity from atrium followed by large sensed ventricular complex. Fluoroscopy confirmed that the atrial lead was dislodged and was intermittently prolapsing into the RVOT. Since the patient was asymptomatic, he refused any intervention and subsequentlyhis atrial lead was switched off by telemetry. The above case signifies that asymptomatic lead dislodgement is no talways manifested as loss of capture and even subtle variation of the axis o fthe paced complexes can provide us with a clue that can be confirmed by telemetry of the pacemaker and fluoroscopy.     

Atrial flutter and atrial tachycardia detection using Bayesian approach with high resolution time–frequency spectrum from ECG recordings

Contemporary methods of atrial flutter (AFL), atrial tachycardia (AT), and atrial fibrillation (AF) monitoring, although superior to the standard 12-lead ECG and symptom-based monitoring, are unable to accurately discriminate between AF, AFL and AT. Thus, there is a need to develop accurate, automated, and comprehensive atrial arrhythmia detection algorithms using standard ECG recorders. To this end, we have developed a sensitive and real-time realizable algorithm for accurate AFL and AT detection using any standard electrocardiographic recording. Our novel method for automatic detection of atrial flutter and atrial tachycardia uses a Bayesian approach followed by a high resolution time–frequency spectrum. We find the TQ interval of the electrocardiogram (ECG) corresponding to atrial activity by using a particle filter (PF), and analyze the atrial activity with a high resolution time–frequency spectral method: variable frequency complex demodulation (VFCDM). The rationale for using a high-resolution time–frequency algorithm is that our approach tracks the time-varying fundamental frequency of atrial activity, where AT is within 2.0–4.0 Hz, AFL is within 4.0–5.3 Hz and NSR is found at frequencies less than 2.0 Hz. For classifications of AFL (n = 22), AT (n = 10) and normal sinus rhythms (NSR) (n = 29), we found that our approach resulted in accuracies of 0.89, 0.87 and 0.91, respectively; the overall accuracy was 0.88.     

Getting a G--RRP on regulated exocytosis in the heart

A study by Rybkin et al. (see p. 527) substantially advances our understanding of regulated exocytois by specialized secretory cells, such as atrial myocytes. A second member of the Ras-related protein family, RRP17, was identified and shown to participate in regulating the secretion of the cardiac-derived peptide hormone, atrial natriuretic peptide. In addition to the heart, RRP17 was shown to be expressed in neuronal, pancreatic, and skeletal muscle cells, suggesting a widespread role in regulated secretion for this new protein.     

永久起搏器程控在心房颤动诊断中的临床应用及意义

摘要 目的：探究永久起搏器程控在心房颤动诊断中的临床应用及意义。方法：选择78例我院收治的心房颤动患者随机分为程控组和非程控组2组,其中观察组患者给与永久起搏器程控诊断,非程控组则仅给植入永久起搏器,但非程控。对比分析两组患者基本资料、房颤负荷、心房与心室起搏比、心房结构重构及左心功能、P波结果;比较永久起搏器程控诊断与临床诊断结果的差异,分析永久起搏器程控在心房颤动诊断敏感度。结果：程控组和非程控组患者的男女比例、年龄、心率失常的类型、存在的基础性疾病以及使用过的治疗药物比较,差异均无统计学意义（P>0.05）;程控组和非程控组患者的房颤负荷、VP值和P波最小时限均显著小于非程控组,AP值、P波最大时限和P波离散度则显著大于非程控组（P<0.05）;程控组和非程控组患者的LAD、RAD、LVEDD和LVEF值在植入前和植入后均不存在显著性差异（P>0.05）。与临床诊断结果比较可以发现,永久起搏器程控对心房颤动检出率为97.44 %,且永久起搏器程控应用于诊断心房颤动敏感度高达98.72 %。结论：对心房颤动患者采用永久起搏器程控进行诊断,可以在心电图检查的各项指标结果上对患者的心房颤动给与准确的判断,具有较高的临床应用价值,值得临床推广使用。     

Right atrial tumor: a contraindication to minimally invasive surgery?

Cardiac tumors are rarely observed. The incidence of primary cardiac tumors in autopsy series ranges from 0.0017% to 0.19%. Surgical resection is the main therapy for the majority of the cardiac tumors. Surgical treatment of these tumors carries an operative mortality rate of 3% or less. In this article, we present our experience with a female patient, who had a right sided atrial tumor mimicking a myxoma. Port access surgery was performed through a small right sided "key-hole" working port in the fourth intercostal space. Extracorporeal circulation was conducted by femoro-femoral bypass and a kinetic assisted venous drainage system. Although, the safety and efficacy of port access approach have been well documented for resection of left atrial tumors in some series, use of this technique for right atrial tumor resection can be detrimental.     

Identification in rat atrial tissue of multiple forms of natriuretic polypeptides of about 3,000 daltons

Rat atrial natriuretic peptides of relatively low molecular weight have been isolated from the alpha-component of rectum relaxant activity corresponding to about 3,000 daltons, which was obtained as a side fraction in our previous isolation of beta-rat atrial natriuretic polypeptide (beta- rANP ). In contrast to the same fraction from human atria, the rat atrial alpha-component was found to contain six or more distinct but related peptides, eliciting a potent natriuretic activity. Six of them (B-II, C, D, E, B-I and A), containing 35, 33, 32, 31, 28 and 25 amino acid residues, respectively, have been purified to homogeneity and sequenced. All these peptides were found to correspond to the C-terminal sequence of beta- rANP composed of 48 residues, with varying N-terminal elongations. This indicates that these peptides are derived from beta- rANP . Peptide B-I, composed of 28 residues, is identical to alpha-human atrial polypeptide(alpha- hANP ), with a single replacement of Ile for Met at position 12.     

Serum Levels of the Biomarkers Associated with Astrocytosis,Neurodegeneration, and Demyelination: Neurological Benefits of Citicoline Treatment of Patients with Ischemic Stroke and Atrial Fibrillation

Neurophysiology - Ischemic stroke is a main complication of atrial fibrillation (cardiac arrhythmia). The aim of our study was to estimate the effects of citicoline (CDP-choline) therapy on the...     

Determinants of heterogeneity, excitation and conduction in the sinoatrial node: a model study

The sinoatrial node (SAN) is a complex structure that exhibits anatomical and functional heterogeneity which may depend on: 1) The existence of distinct cell populations, 2) electrotonic influences of the surrounding atrium, 3) the presence of a high density of fibroblasts, and 4) atrial cells intermingled within the SAN. Our goal was to utilize a computer model to predict critical determinants and modulators of excitation and conduction in the SAN. We built a theoretical "non-uniform" model composed of distinct central and peripheral SAN cells and a "uniform" model containing only central cells connected to the atrium. We tested the effects of coupling strength between SAN cells in the models, as well as the effects of fibroblasts and interspersed atrial cells. Although we could simulate single cell experimental data supporting the "multiple cell type" hypothesis, 2D "non-uniform" models did not simulate expected tissue behavior, such as central pacemaking. When we considered the atrial effects alone in a simple homogeneous "uniform" model, central pacemaking initiation and impulse propagation in simulations were consistent with experiments. Introduction of fibroblasts in our simulated tissue resulted in various effects depending on the density, distribution, and fibroblast-myocyte coupling strength. Incorporation of atrial cells in our simulated SAN tissue had little effect on SAN electrophysiology. Our tissue model simulations suggest atrial electrotonic effects as plausible to account for SAN heterogeneity, sequence, and rate of propagation. Fibroblasts can act as obstacles, current sinks or shunts to conduction in the SAN depending on their orientation, density, and coupling.