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Atrial Area (atrial + area)
Selected AbstractsMitral Regurgitation Associated with Mitral Annular Dilation in Patients with Lone Atrial Fibrillation: An Echocardiographic StudyECHOCARDIOGRAPHY, Issue 8 2009Takashi Kihara M.D. Background: Whether and how lone atrial fibrillation (AF) is associated with functional mitral regurgitation (MR) remain unclear. Method: We studied 12 lone AF patients without left ventricular (LV) dysfunction and/or dilatation, who underwent mitral valve annuloplasty for functional mitral regurgitation (MR). Ten lone AF patients without MR served as controls. Results: Lone AF Patients with MR had a greater mitral valve annular area and left atrial area than those without MR. There were no differences in LV volumes or LV ejection fraction. Conclusions: Therefore, we concluded that left atrial dilation and corresponding mitral annular dilation may cause MR in lone AF patients without LV dysfunction and/or dilatation. [source] Correlation of Left Atrial Diameter by Echocardiography and Left Atrial Volume by Computed TomographyJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 2 2009IRENE HOF M.D. Introduction: For patients undergoing catheter ablation of atrial fibrillation (AF), left atrial size is a predictor of recurrence of AF during follow-up. For this reason, major clinical trials have used a left atrial diameter (LAD) of more than 5.0 or 5.5 cm, assessed by echocardiography, as an exclusion criterion for patients deemed candidates for ablation of AF. However, whether LAD accurately reflects true left atrial size has not been systematically investigated. Therefore, the purpose of this study was to test the hypothesis that LAD, measured by echocardiography, accurately correlates to left atrial volume measured by computed tomography (CT). Methods and Results: We included 50 patients (mean age 56 ± 12 years, five female) with symptomatic AF (40% paroxysmal, 60% persistent), referred for catheter ablation. In each patient, transthoracic echocardiography was performed. Additionally, all patients underwent CT using a 64-slice CT scanner. Left atrial volume was calculated by manually tracing left atrial area on each CT cross-sectional image. Patients had a mean LAD measured by echocardiography of 4.5 ± 0.7 cm, ranging from 2.9 to 5.7 cm. Left atrial volume measured by CT ranged from 67 mL to 270 mL with a mean value of 146 ± 49 mL. A poor correlation was noted between LAD and left atrial volume, r = 0.49 (P < 0.001). Conclusion: LAD measured by echocardiography correlates poorly with left atrial volume measured by CT in patients with AF. As a result, selecting patients with AF for treatment with catheter ablation should not be based on an echocardiographic-derived LAD alone. [source] Anatomy of the Pulmonary Veins in Patients with Atrial Fibrillation and Effects of Segmental Ostial Ablation Analyzed by Computed TomographyJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 2 2003CHRISTOPH SCHARF M.D. Pulmonary Vein Anatomy.Introduction: The anatomic arrangement of pulmonary veins (PVs) is variable. No prior studies have quantitatively analyzed the effects of segmental ostial ablation on the PVs. The aim of this study was to determine the effect of segmental ostial radiofrequency ablation on PV anatomy in patients with atrial fibrillation (AF). Methods and Results: Three-dimensional models of the PVs were constructed from computed tomographic (CT) scans in 58 patients with AF undergoing segmental ostial ablation to isolate the PVs and in 10 control subjects without a history of AF. CT scans were repeated approximately 4 months later. PV and left atrial dimensions were measured with digital calipers. Four separate PV ostia were present in 47 subjects; 3 ostia were present in 2 subjects; and 5 ostia were present in 9 subjects. The superior PVs had a larger ostium than the inferior PVs. Patients with AF had a larger left atrial area between the PV ostia and larger ostial diameters than the controls. Segmental ostial ablation resulted in a 1.5 ± 3.2 mm narrowing of the ostial diameter. A 28% to 61% focal stenosis was present 7.6 ± 2.2 mm from the ostium in 3% of 128 isolated PVs. There were no instances of symptomatic PV stenosis during a mean follow-up of 245 ± 105 days. Conclusion: CT of the PVs allows identification of anatomic variants prior to catheter ablation procedures. Segmental ostial ablation results in a significant but small reduction in ostial diameter. Focal stenosis occurs infrequently and is attributable to delivery of radiofrequency energy within the PV. (J Cardiovasc Electrophysiol, Vol. 14, pp. 150-155, February 2003) [source] Atrial Size Reduction as a Predictor of the Success of Radiofrequency Maze Procedure for Chronic Atrial Fibrillation in Patients Undergoing Concomitant Valvular SurgeryJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 8 2001MIEN-CHENG CHEN M.D. Radiofrequency Maze Procedure and Atrial Size.Introduction: Previous studies showed that the surgical maze procedure can restore sinus rhythm and atrial transport function in patients with chronic atrial fibrillation (AF). However, no previous studies discussed the association of atrial size reduction and the success of sinus conversion by the radiofrequency (RF) maze procedure for chronic AF. Methods and Results: A total of 119 chronic AF patients undergoing valvular operations were included in this study. Sixty-one patients received RF and cryoablation to create lesions in both atria to simulate the surgical maze II or III procedure (RF maze II or RF maze III; 13 patients, group 1) or a modified maze pattern (RF maze "IV"; 48 patients, group 2). The other 58 patients who underwent valvular operations alone without the maze procedure served as control (group 3). At 3-month follow-up after operation, sinus rhythm was restored in 73%, 81%, and 11% of patients in groups 1, 2 and 3, respectively. Preoperative left and right atrial sizes were not statistically significant predictors of sinus conversion by the RF maze procedure. However, as a result of postoperative reduction of atrial sizes, postoperative left atrial diameter was significantly smaller in patients who had sinus conversion by the RF maze procedure than in patients who did not regain sinus rhythm (45.0 ± 7.0 mm vs 51.0 ± 8.0 mm; P = 0.03). Postoperative right atrial area of patients who had sinus conversion by the RF maze procedure also was significantly smaller than that of patients who did not regain sinus rhythm (18.1 ± 4.4 cm2 vs 28.5 ± 8.2 cm2; P = 0.008). Conclusion: Atrial size reduction appears to predict the success of sinus conversion with the RF maze procedure used in conjunction with valvular surgery. [source] Decreased Platelet Function in Cavalier King Charles Spaniels with Mitral Valve RegurgitationJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 5 2003Inge Tarnow With aggregometry, increased platelet activity has been reported in Cavalier King Charles Spaniels (CKCS) without mitral regurgitation (MR). In contrast, dogs with MR have been found to have decreased platelet activity. The purpose of this study was to test an easy bedside test of platelet function (the Platelet Function Analyzer [PFA-100]) to see if it could detect an increase in platelet activity in CKCS without MR and a decrease in platelet activity in CKCS with MR. This study included 101 clinically healthy dogs 1 year of age: 15 control dogs of different breeds and 86 CKCS. None of the dogs received medication or had a history of bleeding. The PFA-100 evaluates platelet function in anticoagulated whole blood under high shear stress. Results are given as closure times (CT): the time it takes before a platelet plug occludes a hole in a membrane coated by agonists. The CT with collagen and adenosine-diphosphate as agonists was similar in control dogs (median 62 seconds; interquartile interval 55,66 seconds) and CKCS with no or minimal MR (55; 52,64 seconds). The CT was higher in CKCS with mild MR (regurgitant jet occupying 15,50% of the left atrial area) (75; 60,84 seconds; P= .0007) and in CKCS with moderate to severe MR (jet 50%) (87; 66,102 seconds; P < .0001). CKCS with mild, moderate, and severe, clinically inapparent MR have decreased platelet function. The previous finding of increased platelet reactivity in nonthrombocytopenic CKCS without MR could not be reproduced with the PFA-100 device. [source] Decreased Plasma Concentration of Nitric Oxide Metabolites in Dogs with Untreated Mitral RegurgitationJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 2 2003Henrik D. Pedersen Endothelium-dependent (nitric oxide [NO]-mediated) vasodilation is impaired in humans with heart failure. This dysfunction is an important therapeutic target. The plasma concentration of the NO metabolites nitrate and nitrite (collectively referred to as NOx) is a measure of whole-body NO production, provided that the dietary intake of the ions is low. Fifty clinically healthy dogs older than 1 year (median 5.0 years; interquartile interval 2.6,8.2 years) were studied, including 9 controls of various breeds, 23 Cavalier King Charles Spaniels (CKCSs) with no or minimal mitral regurgitation (MR), 9 CKCSs with mild MR (regurgitant jet occupying 15,50% of the left atrial area), and 9 CKCS with moderate to severe MR (jet ± 50%) due to myxomatous valve disease. None of the dogs received medication. The dogs were given NOx-free water and a diet with a low concentration of NOx for 96 hours before blood sampling. Multiple linear regression analysis revealed that dog group, but not gender, age, serum creatinine concentration, and platelet count, was associated with NOx concentrations. Control dogs had the same NOx concentration (median 20.0 ,M; interquartile interval 15.1,25.5 ,M) as CKCSs without MR (median 18.7 ,M; interquartile interval 15.5,25.9 ,M). Compared to CKCSs without MR, the NOx concentration was lower in CKCSs with mild (median 12.9 ,M; interquartile interval 11.0,13.5 ,M; P= .04) and moderate to severe (median 11.2 ,M; interquartile interval 6.9,17.1 ,M; P= .02) MR. In conclusion, CKCSs with mild to severe, clinically silent MR have decreased plasma NOx concentrations, suggesting that endothelial dysfunction develops early in the course of developing MR in dogs. [source] Effect of Different Pacing Protocols on the Induction of Atrial Fibrillation in a Transvenously Paced Sheep ModelPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 6 2001RIK WILLEMS WILLEMS, R. et al.: Effect of Different Pacing Protocols on the Induction of Atrial Fibrillation in a Transvenously Paced Sheep Model. In different animal models rapid atrial stimulation led to a shortening and maladaptation to rate of the atrial effective refractory period (AERP). This atrial electrical remodeling resulted in an increased vulnerability to atrial fibrillation (AF). These experimental findings formed the rationale for a stringent pursuit of sinus rhythm in patients with AF, since this would prevent or reverse atrial remodeling. This study tested the hypothesis that a reduction of arrhythmia burden would lead to a decreased vulnerability for AF. Different rapid atrial pacing protocols in a sheep model were used. During 15 weeks, 13 animals were continuously rapid paced and 7 animals were intermittently burst-paced, resulting in rapid atrial activation during 100% versus 33 ± 4% of the time, respectively. In the continuously paced group, 77% of the animals developed sustained AF (i.e., >1 hour) versus only 29% in the burst-paced group (P < 0.05). However, there was no difference in mean AERP shortening over time, nor maximal AERP shortening per animal, between both protocols. Minimal AERP was 103 ± 5 ms in the continuously paced group and 107 ± 5 in the burst-paced group (P = NS). Significant changes could be identified in effect on P wave duration, AVN function, and atrial dilation. Conduction slowing was more pronounced in the continuously paced group with a maximal P wave duration of 136 ± 4 ms in this group versus 116 ± 5 in the burst-paced group (P < 0.05). In the continuously paced group, the right atrial area significantly increased from 2.5 ± 0.1 cm2 at baseline to 4.2 ± 0.2 cm2. In the burst-paced group there was no significant atrial dilatation (from 2.6 ± 0.1 to 2.8 ± 0.1 cm2). In conclusion, limiting atrial arrhythmia burden slowed the development of sustained AF in this sheep model. This was not mediated by a decreased influence on atrial refractoriness but seemed to be dependent on smaller changes in atrial conduction and dimensions. [source] Fibrillating Areas Isolated within the Left Atrium after Radiofrequency Linear Catheter AblationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 8 2006THOMAS ROSTOCK M.D. Introduction: Nonpulmonary vein sources have been implicated as potential drivers of atrial fibrillation (AF). This observational study describes regions of fibrillating atrial tissue isolated inadvertently from the left atrium (LA) following linear catheter ablation for AF. Methods and Results: We report four patients with persistent/permanent AF who underwent pulmonary vein isolation with additional linear lesions and who presented with recurrent AF (mean AF cycle length [AFCL] 175,270 ms). Further catheter ablation resulted in the inadvertent electrical isolation of significant areas of the LA in which AF persisted at the same AFCL as was measured prior to disconnection, despite the restoration of sinus rhythm (SR) in all other left and right atrial areas, strongly suggesting that these islands were driving the remaining atria into fibrillation. The disconnected areas were located in the lateral LA, including the left atrial appendage (LAA) in three patients (limited to the LAA in one) and in the posterior LA in one patient. These isolated fibrillating regions represented 15,24% of the global LA surface, as estimated by electroanatomic mapping. Conclusion: Fibrillation can be maintained within electrically isolated regions of the LA following catheter ablation of AF, demonstrating the importance of atrial drivers in the maintenance of AF. Further mapping of these drivers is needed to characterize their mechanism and thereby allow for a more specific ablation strategy. 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