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At least 289 records · Page 16Linked to original sources
PubMed2004

Left atrial structure and function after percutaneous left atrial appendage transcatheter occlusion (PLAATO): six-month echocardiographic follow-up.

OBJECTIVES: This study was designed to evaluate the effects of percutaneous left atrial appendage transcatheter occlusion (PLAATO) on the anatomic and hemodynamic properties of the mitral valve (MV) and left upper pulmonary vein (LUPV). BACKGROUND: PLAATO is a device designed to seal the neck of the left atrial (LA) appendage and reduce embolization in patients with atrial fibrillation intolerant of warfarin. The impact of deployment of this device on adjacent structures has not been reported. METHODS: Patients with atrial fibrillation participating in the ongoing study for evaluation of PLAATO were enrolled. Transesophageal echocardiographies at baseline, one, and six months were reviewed to measure LA and LUPV dimensions, degree of mitral regurgitation, stability of the device, peak MV E-wave velocity, and peak systolic and diastolic flow velocities in the LUPV. Data were analyzed by a linear mixed model for repeated measures. RESULTS: Eleven patients (mean age of 72 +/- 7 years) completed six months of follow-up. Left upper pulmonary vein diameter (mean: 1.55, 1.61, 1.54 cm, p = 0.13) and peak systolic (mean: 0.38, 0.34, 0.31 m/s, p = 0.72) and diastolic flow velocities (mean: 0.39, 0.40, 0.42 m/s, p = 0.46) did not differ over the follow-up period. Left atrial size, mitral regurgitation severity, and MV peak E-wave velocities (mean: 0.94, 0.94, 0.82 m/s, p = 0.58) showed no significant change from baseline. The devices remained stable at their sites of deployment with minimal residual flow around them. CONCLUSIONS: PLAATO achieved an adequate seal of the neck of the left atrial appendage without significant effect on the structure or function of the LA and LUPV.

Aged↗
PubMed2000

[Restoration of the left atrial mechanical function after successful electrical cardioversion].

Some papers indicate that restoration of the left atrial mechanical function (LAMF) can be delayed to even 7 days after successful electrical cardioversion. The goals of the paper include the estimation of delay in restoration of LAMF and factors that influence it. 75 patients (53 males and 22 females, av. age 56.5 +/- 10.8) after elective electrical cardioversion underwent daily echocardiography to determine LAMF, taking A/E ratio > 1/3 as a criterion. The patients were divided into 2 subgroups: G1--with restoration of LAMF < 24 h after cardioversion and G2: the remaining ones. The analysed parameters were: left atrium diameter, rheumatic valvular disease, duration of atrial fibrillation, global and segmental contractility disorders. The data were analysed with ANOVA. The restoration of LAMF < 24 h was found in 53 patients; on the 2nd day in 6 patients, on the 3rd-8th day in 14 patients. In 2 patients no LAMF could be found on the 14th day after cardioversion. Failure to restore LAMF on the cardioversion day was related to: left atrium enlargement, rheumatic valvular disease, duration of atrial fibrillation > 14 days and contractility disorders.

Atrial Fibrillation↗
PubMed1980

Mechanical hyperventilation: effect on specialized atrioventricular conduction, supraventricular refractoriness, and experimental atrial arrhythmias in dogs anesthetized with pentobarbital or pentobarbital-halothane.

The effect of hypocapnia (PCO2ET 25 vs 40 torr) on specialized atrioventricular (AV) conduction, supraventricular refractory periods, and experimental atrial arrhythmias provoked by premature atrial stimulation (atrial echoes-echoes, repetitive atrial firing (RAF)) was assessed in dogs anesthetized with pentobarbital or pentobarbital-halothane (1.0% end-tidal). Catheter His bundle electrocardiography was used. Both hypocapnia and halothane prolonged AV nodal conduction, but the effect of halothane was more pronounced. Halothane prolonged the atrial functional (AtFRP), atrial effective (AtERP), and AV nodal functional refractory (AVFRP) periods. These effects of halothane were linked to an increased incidence of RAF but not to echoes. Hypocapnia prolonged the AVFRP (less than halothane), had no effect on the AtFRP and shortened the AtERP. These effects of hypocapnia were associated with an increased incidence of echoes, but not with RAF. Echoes and RAF are thought to be caused by reentry within the sinus node, atria, and AV node. The differing effects of halothane and hypocapnia on the incidence of these arrhythmias may be due to differning effects on supraventricular refractoriness.

Anesthesia↗
PubMedDate not supplied

Stroke in paced patients with sick sinus syndrome: relevance of atrial mechanical function, pacing mode and clinical characteristics.

Patients with sick sinus syndrome have a high prevalence of cerebral ischemia and emboli of the viscera and extremities. The present study was designed to establish the prevalence of stroke in patients with sick sinus syndrome, with specific attention to pacing mode, atrial function (evaluated using Doppler echocardiography) and the clinical condition of the patients. The prospective study analyzed 80 consecutive patients with sick sinus syndrome who received either atrial, dual chamber or ventricular pacemakers. Patients underwent a cranial CT scan at the time of enrollment and again at the end of the study 24 months later. End points of the study were cerebral ischemia or emboli of the viscera or extremities. Clinical and echocardiographic features were assessed at the beginning of the study. A multivariate regression analysis was applied to all variables that had at least a marginal univariate predictive value. Cerebral ischemia occurred in 13 patients and emboli of the viscera or extremities were observed in 2 patients. Univariate predictors for embolism consisted of a prior history of cerebrovascular disease (p < 0.001), low atrial ejection force (p < 0.01) and a dilated left atrium with spontaneous echo contrast (p < 0.05). Independent risk factors for stroke included a history of previous cerebral ischemia, age > 65 years, left atrial echo contrast on an echocardiogram and a depressed atrial ejection force. These findings identified patients at high risk for the development of peripheral embolism among the group of patients paced for sick sinus syndrome.

Adolescent↗
PubMedDate not supplied

Intracellular pH regulatory mechanism in human atrial myocardium: functional evidence for Na(+)/H(+) exchanger and Na(+)/HCO(3)(-) symporter.

Intracellular pH (pH(i)) exerts considerable influence on cardiac contractility and rhythm. Over the last few years, extensive progress has been made in understanding the system that controls pH(i) in animal cardiomyocytes. In addition to the housekeeping Na(+)-H(+) exchanger (NHE), the Na(+)-HCO(3)(-) symporter (NHS) has been demonstrated in animal cardiomyocytes as another acid extruder. However, whether the NHE and NHS functions exist in human atrial cardiomyocytes remains unclear. We therefore investigated the mechanism of pH(i) recovery from intracellular acidosis (induced by NH(4)Cl prepulse) using intracellular 2',7'-bis(2-carboxethyl)-5(6)-carboxy-fluorescein fluorescence in human atrial myocardium. In HEPES (nominally HCO(3)(-)-free) Tyrode solution, pH(i) recovery from induced intracellular acidosis could be blocked completely by 30 microM 3-methylsulfonyl-4-piperidinobenzoyl, guanidine hydrochloride (HOE 694), a specific NHE inhibitor, or by removing extracellular Na(+). In 3% CO(2)-HCO(3)(-) Tyrode solution, HOE 694 only slowed the pH(i) recovery, while addition of HOE 694 together with 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (an NHS inhibitor) or removal of extracellular Na(+) inhibited the acid extrusion entirely. Therefore, in the present study, we provided evidence that two acid extruders involved in acid extrusion in human atrial myocytes, one which is HCO(3)(-) independent and one which is HCO(3)(-) dependent, are mostly likely NHE and NHS, respectively. When we checked the percentage of contribution of these two carriers to pH(i) recovery following induced acidosis, we found that the activity of NHE increased steeply in the acid direction, while that of NHS did not change. Our present data indicate for the first time that two acid extruders, NHE and NHS, exist functionally and pH(i) dependently in human atrial cardiomyocytes.

Fluoresceins↗
PubMed2001

Discrimination between ventricular and supraventricular tachycardia by dual chamber cardioverter defibrillators: importance of the atrial sensing function.

Although the addition of atrial sensing in dual chamber ICDs may improve the ability of the device to discriminate between supraventricular (SVT) and ventricular tachycardia (VT), atrial sensing errors may also negatively affect tachycardia classification. This prospective study evaluated the incidence of atrial sensing errors in a dual chamber ICD and their impact on VT/SVT discrimination. In 145 patients, a dual chamber ICD (Defender) was implanted. Analysis of 1,241 tachycardia episodes stored during a mean follow-up of 14+/-8 months revealed atrial sensing errors in 817 (66%) episodes. Upon expert review, device-based classification was confirmed in 509 (98%) of 522 SVT episodes. No false device-based SVT classification was related to atrial sensing errors. Of 719 episodes classified as VT by the device, 645 (90%) were confirmed. There were 74 episodes of false-positive VT detection. Of these, 63 were related to atrial sensing errors: atrial undersensing in 58 (92%) and atrial oversensing in 5 (8%) episodes. Atrial sensing errors led to incorrect VT/SVT discrimination in 51 (4%) of 1,241 episodes. Only the occurrence of paroxysmal atrial fibrillation and abdominal site of device implantation showed a significant influence on false VT/SVT discrimination. Atrial sensing errors are frequently encountered in dual chamber ICDs. Due to the VT/SVT discrimination algorithm, atrial sensing errors only led to misclassification in 4 % of all episodes, mainly due to atrial undersensing. No VT underdetection due to atrial oversensing occurred.

Algorithms↗
PubMed1985

Fast algorithms for the analysis of sino-atrial node function.

The calculations of parameters of the sino-atrial node function have previously required the application of a non-linear least squares curve-fitting algorithm. We have compared five algorithms, three of which eliminate the need for direct non-linear least squares routines. The fast algorithms can provide greater accuracy while using less than 10% of the computing time. They make it feasible to provide real-time analysis during clinical electrophysiological studies.

Arrhythmias, Cardiac↗
PubMed2005

The use of anatomic M-mode echocardiography to determine the left atrial appendage functions in patients with sinus rhythm.

Left atrial appendage (LAA) contractile dysfunction is associated with thrombus formation and systemic embolism. LAA function is determined by its flow velocities and fractional area change. This study was performed in order to determine the LAA functions with the anatomic M-mode echocardiography (AMME). Our study comprised 74 patients who had sinus rhythm and underwent transesophageal echocardiography (TEE) for various reasons. LAA fractional change (LAAFAC) was measured by manual planimetry in a transverse basal short-axis approach and LAA emptying and filling velocities also were measured. The AMME values were determined by an M-mode cross section from a cursor placed beneath the orifice of the LAA in transverse basal short-axis imaging. From these values LAA fractional shortening (LAAFS) and ejection fraction (LAAEF) were calculated. LAAEF was calculated by the Teicholz method. The comparisons were conducted, and no correlations between the LAA late filling and the anatomic M-mode values were found (for LAAFS r = 0.18; P > 0.05 and for LAAEF r = 0.19; P > 0.05). There were significant but poor correlations among the LAA late emptying with the anatomic M-mode measurements (for LAAFS r = 0.26; P < 0.05 and for LAAEF r = 0.30; P < 0.01), whereas, there were significant and good correlations between the LAAFAC and the anatomic M-mode values (for LAAFS r = 0.75; P < 0.01 and for LAAEF r = 0.78; P < 0.01). There were significant differences between the valvular heart disease group and the normal group, and between the valvular heart disease group and the ASD group (for LAAFAC P < 0.01, for LAAEF P < 0.01, for LAAFS P < 0.01). There was no difference between the normal group and the ASD group. Our study showed that the LAAEF and LAAFS in patients with sinus rhythm obtained via anatomical M-mode echocardiography is a new method, which can be used instead of left atrial appendage area change.

Adult↗
PubMed1997

Evaluation of left atrial appendage function by measurement of changes in flow velocity patterns after electrical cardioversion in patients with isolated atrial fibrillation.

We investigated temporary changes in left atrial appendage (LAA) flow velocity patterns in patients undergoing electrical cardioversion for chronic isolated atrial fibrillation, and evaluated the role of active LAA contraction in directing blood flow to the left atrial main chamber and left ventricle. The study consisted of 26 patients with chronic isolated atrial fibrillation treated with electrical cardioversion and 20 normal controls in sinus rhythm. Using transthoracic and transesophageal Doppler echocardiography, we recorded transmitral, pulmonary venous, and LAA flow velocity patterns before, 24 hours, and 1 week after cardioversion in all subjects. In the 15 patients who underwent successful cardioversion, the maximal LAA area 24 hours after cardioversion was smaller than the area before cardioversion, whereas LAA ejection fraction during atrial systole and peak atrial systolic emptying velocity of the LAA flow were lower 24 hours after cardioversion than those in the control group. One week after cardioversion, maximal LAA area and LAA peak atrial systolic emptying velocity were restored to levels approximately equivalent to those in the control group, although LAA ejection fraction was lower than in the control group. Maximal LAA area and LAA peak atrial systolic emptying velocity correlated negatively and positively with LAA ejection fraction, respectively, 24 hours and 1 week after cardioversion. These results suggest that LAA and the left atrial main chamber show stunning 24 hours after cardioversion, and the atrial systolic emptying wave of LAA flow is generated by active LAA contraction.

Adult↗
PubMed1999

Imaging of thrombi and assessment of left atrial appendage function: a prospective study comparing transthoracic and transoesophageal echocardiography.

OBJECTIVE: To compare the value of current transthoracic echocardiographic systems and transoesophageal echocardiography for assessing left atrial appendage function and imaging thrombi. DESIGN: Single blind prospective study. Patients were first investigated by transthoracic echocardiography and thereafter by a second investigator using transoesophageal echocardiography. The feasibility of imaging the left atrial appendage, recording its velocities, and identifying thrombi within the appendage were determined by both methods. PATIENTS: 117 consecutive patients with a stroke or transient neurological deficit. SETTING: Tertiary cardiac and neurological care centre. RESULTS: Imaging of the complete appendage was feasible in 75% of the patients by transthoracic echocardiography and in 95% by transoesophageal echocardiography. Both methods were concordant for the detection of thrombi in 10 cases. Transoesophageal echocardiography revealed two additional thrombi. In one of these patients, transthoracic echocardiography was not feasible and in the other the thrombus had been missed by transthoracic examination. In patients with adequate transthoracic echogenicity, the specificity and sensitivity of detecting left atrial appendage thrombi were 100% and 91%, respectively. Recording of left atrial appendage velocities by transthoracic echocardiography was feasible in 69% of cases. None of the patients with a velocity > 0.3 m/s had left atrial appendage thrombi. In the one patient in whom transthoracic echocardiographic evaluation missed a left atrial appendage thrombus, the peak emptying velocity of the left atrial appendage was 0.25 m/s. CONCLUSIONS: A new generation echocardiographic system allows for the transthoracic detection of left atrial appendage thrombi and accurate determination of left atrial appendage function in most patients with a neurological deficit.

Adult↗
PubMed1996

Surgery for supraventricular tachycardia.

1995 is the fifth anniversary of the advent of catheter ablation for the treatment of supraventricular tachycardia. Surgery has established the principles of the interventional approaches: 1) identification of the mechanism; 2) localization of the site of the mechanism; 3) identification of the anatomical arrhythmogenic substrate and its localization using preoperative and intraoperative electrophysiological cardiac mapping; 4) ablation of the arrhythmogenic substrate using "surgical" dissection or excision or various forms of energy to neutralize the substrate: cryoablation, laser, etc. Surgical approaches also established the EP interventions as the first line of therapy because they are curative. Currently, surgery for supraventricular tachycardia is essentially confined to atrial fibrillation, and after attempted catheter ablation for the Wolff-Parkinson-White syndrome. Atrial fibrillation is a complex arrhythmia, commonly associated with structural heart disease. To understand atrial fibrillation, a number of premises should be reviewed: atrial functional anatomy, atrial pathology, atrial fibrillation mechanism (s) and clinical presentation. The role of atrial fibrillation in terms of symptoms, morbidity and mortality is not clear because it is difficult to determine if atrial fibrillation is a symptom, a marker, an autonomous disease albeit it is in most cases an aggravating factor. Surgical rationales for atrial fibrillation are based on three concepts: exclusion, fragmentation and channelling. The Corridor operation was the first used direct surgical approach. The Maze operation and other techniques (fragmentation, spiral) have been reported. All surgical techniques have been reported with good results in terms of sinus node function and exercise tolerance, and to various degrees, in terms of atrial contraction. Currently, there is a trend to combine direct atrial fibrillation surgery with surgery for mitral valve albeit beneficial effects are not documented.

Atrial Fibrillation↗
PubMedDate not supplied

Relationship of left atrial appendage function to left ventricular function.

BACKGROUND: The study was conducted to evaluate the relationship of left atrial appendage function to left ventricular function and to analyze, if left ventricular dysfunction predisposed to left atrial appendage thrombus formation even in the presence of sinus rhythm. METHODS AND RESULTS: The study was conducted in 78 patients with a mean age of 53+/-8.5 years, all of whom were in sinus rhythm. Transesophageal echocardiography was performed to record the left atrial appendage emptying and filling velocity and to look for the presence of spontaneous echo contrast and thrombus. Patients with severe left ventricular dysfunction (Group I--left ventricular ejection fraction < 35%) and patients with moderate left ventricular dysfunction (Group II--left ventricular ejection fraction 35-45%) had lower left atrial appendage emptying velocity (33.6+/-16 and 39.7+/-19.5 cm/s, respectively) and filling velocity (41+/-14.7 and 41+/-17 cm/s, respectively) when compared to patients with preserved systolic function (Group II--left ventricular ejection fraction >45%), who had emptying and filling velocity of 55+/-16 and 56+/-15 cm/s, respectively (p <0.05). Twelve out of 32 (38%) patients with severe left ventricular dysfunction (Group I) and 7 out of 25 (28%) patients with moderate left ventricular dysfunction (Group II) had presence of left atrial appendage thrombus as compared to none of the patients with preserved left ventricular ejection fraction (Group III) (p <0.001). CONCLUSIONS: Patients with left ventricular dysfunction also had left atrial appendage dysfunction as evidenced by lower emptying and filling velocities and had increased incidence of thrombus formation.

Atrial Appendage↗
PubMed2005

Embolic stroke, sinus rhythm and left atrial mechanical function.

A 64-year-old man manifested a stroke two years after restoration of sinus rhythm through a radiofrequency catheter ablation. Transesophageal echocardiography demonstrated the presence of a thrombus in the left atrial appendage. Left atrial volumes and different parameters of atrial emptying showed that, despite the persistence of the sinus rhythm, atrial mechanical function was severely impaired. After atrial ablation procedures echocardiography can be useful to stratify patients according to their risk of developing embolic events and hence be of help in deciding whether or not discontinuation of anticoagulant therapy is the appropriate choice.

Atrial Appendage↗
PubMed2000

[Study of spontaneous echo contrast in patients with rheumatic mitral stenosis by transesophageal echocardiography].

Spontaneous echo contrast (SEC) is common in the areas of slow blood flow. This study was conducted to examine the correlation of SEC and left atrial appendage function, atrial fibrillation (Af) and thrombus in patients with rheumatic mitral stenosis. The transthoracic and multiplane transesophageal echocardiograms were performed on 117 patients(mean age 42.22 +/- 10.79 years). Left atrial size, left atrial appendage area, mitral valve area, left atrial appendage flow peak emphatic velocity and full velocity were measured. The presence of SEC and thrombus in the left atrium and appendage was noted. The results showed that among the patients, 57 had normal sinus rhythm, 60 had Af; 19 had thrombus, 98 had no thrombus; 71 had SEC and 46 had no SEC. Compared with the patients without SEC, the patients with SEC showed greater incidence of thrombus (28.76% vs 0, P < 0.05), higher rate of Af (69.01% vs 23.91%, P < 0.05), larger LAD (46.93 +/- 0.85 mm vs. 41.76 +/- 1.05 mm, P < 0.05), larger LAA area (8.06 +/- 0.32 cm2 vs 6.92 +/- 0.31 cm2, P < 0.05), smaller MVA area (1.07 +/- 0.23 cm2 vs 1.32 +/- 0.35 cm2, P < 0.05), lower LAA flow peak emphatic velocity (0.17 +/- 0.01 m/s vs 0.32 +/- 0.02 m/s, P < 0.05), and lower LAA full velocity (0.18 +/- 0.01 m/s vs 0.31 +/- 0.03 m/s, P < 0.05). These findings indicate that the presence of SEC is associated with significantly greater incidence of thrombus, higher rate of Af, larger LAD and LAA area, smaller MVA area, lower LAA flow peak emphatic velocity and full velocity. Atrial fibrillation, the diameter of left atrium and the area of mitral valve are independent predictors of SEC. SEC is significantly associated with LAA function and thrombus formation.

Adolescent↗
PubMed2005

Left atrial mechanical functions in pre-eclampsia.

AIM: To assess the effect of short-term pressure overload on left atrial (LA) mechanical function in pre-eclampsia. METHODS: Twenty women with pre-eclampsia and 17 age-matched healthy pregnant women were included. LA volumes were measured echocardiographically at the time of mitral valve opening (Vmax), onset of atrial systole (p-wave at the electrocardiography = Vp) and mitral valve closure (Vmin) according to the biplane area-length method. RESULTS: The mean age, gestational age, weight and body surface area were similar in pre-eclampsia and controls. The ventricular septal and posterior wall thickness were greater in pre-eclampsia (P < 0.001). There were no significant differences in LA diameter, Vmax, Vmin, Vp, LA-passive emptying volume, LA-passive emptying fraction, LA-active emptying volume, LA-active emptying fraction, conduit volume, LA-total emptying volume and LA-total emptying fraction between the groups. CONCLUSION: Left atrial mechanical function didn't change in pre-eclampsia. We conclude that short-lasting pressure overload is not capable of inducing changes in LA function.

Adult↗
PubMed2002

Left atrial appendage function in patients with mitral stenosis in sinus rhythm.

AIMS: Left atrial appendage thrombi are believed to be the source of embolism in patients with rheumatic mitral stenosis in atrial fibrillation. There are a few studies which search the effects of left atrial appendage dysfunction in patients with mitral stenosis in sinus rhythm. METHODS AND RESULTS: Left atrial appendage function and flow patterns in 41 patients with rheumatic mitral stenosis in sinus rhythm and 11 healthy subjects were studied by transoesophageal echocardiography. Left atrial appendage flow profiles were recorded within the proximal third of the appendage. The left atrial appendage ejection fraction was expressed as (maximal area of appendage minimal area of appendage)/maximal area of appendage. In addition, two-dimensional imaging was used to determine the presence of spontaneous echocardiographic contrast and thrombus formation. Patients with mitral stenosis in sinus rhythm had significantly decreased left atrial appendage emptying and filling velocities compared to controls (0.40+/-0.15m/s vs 0.82+/-0.19 m/s and 0.42+/-0.21 m/s vs 0.68+/-0.28, respectively, P<0.001 and P<0.05). Compared with the control subjects, patients with mitral stenosis had significantly greater maximal area of the appendage and had reduced left atrial appendage ejection fraction (5.3+/-2.2 cm(2) vs 2.4+/-0.5 cm(2) and 50+/-16% vs 70+/-7%, respectively, P<0.001 and P<0.05). Of the patients with mitral stenosis in sinus rhythm, seven patients had spontaneous echocardiographic contrast and one of these had left atrial appendage thrombus. Compared with patients without spontaneous echocardiographic contrast, patients with spontaneous echocardiographic contrast had decreased left atrial appendage ejection fraction (33+/-21% vs 54+/-13%,P <0.01). One of the patients with mitral stenosis had central retinal artery occlusion, but thrombus was not observed in left atrial appendage. CONCLUSION: The study found that left atrial appendage dysfunction may occur in patients with mitral stenosis in sinus rhythm.

Adult↗