Left atrial wall stress distribution and its relationship to electrophysiologic remodeling in persistent atrial fibrillation.
ABSTRACT Atrial stretch causes remodeling that predisposes to atrial fibrillation. We tested the hypothesis that peaks in left atrial (LA) wall stress are associated with focal remodeling.
Nineteen patients underwent LA mapping before catheter ablation for persistent atrial fibrillation. Finite Element Analysis was used to predict wall stress distribution based on LA geometry from CT. The relationship was assessed between wall stress and (1) electrogram voltage and (2) complex fractionated atrial electrograms (CFAE), using CFAE mean (the mean interval between deflections). Wall stress varied widely within atria and between subjects (median, 36 kPa; interquartile range, 26-51 kP). Peaks in wall stress (≥90th percentile) were common at the pulmonary vein (PV) ostia (93%), the appendage ridge (100%), the high posterior wall (84%), and the anterior wall and septal regions (42-84%). Electrogram voltage showed an inverse relationship across quartiles for wall stress (19% difference across quartiles, P=0.016). There was no effect on CFAE mean across quartiles of wall stress. Receiver operating characteristic analysis showed high wall stress was associated with low voltage (ie, <0.5 mV) and electrical scar (ie, <0.05 mV; both P<0.0001) and with absence of CFAE (ie, CFAE mean <120 ms; P<0.0001). However, peaks in wall stress and CFAE were found at 88% of PV ostia.
Peaks in wall stress were associated with areas of low voltage, suggestive of focal remodeling. Although peaks in wall stress were not associated with LA CFAE, the PV ostia may respond differently.
- SourceAvailable from: Elena S Di Martino[show abstract] [hide abstract]
ABSTRACT: AIMS: To examine morphology and mechanical properties of the atrial 'intima', which we defined as the tissue interposed between atrial endocardium and myocardium, in patients without known cardiovascular disease.METHODS AND RESULTS: Post-mortem right and left atrial tissue was obtained from male infants (<1 year, n = 4), children (10-19 years, n = 4), and adults (58-69 years, n = 7). Using light microscopy and an ocular micrometer, atrial intimal (AIT) thickness was measured. Intimal collagen bundle thickness was measured using electron microscopy. Passive atrial wall stiffness was measured using a planar biaxial testing device. Among infants, left AIT (0.2 ± 0.2 mm) and right (0.2 ± 0.1 mm) AIT were not significantly different (P = 0.84). Among children, left AIT (0.6 ± 0.2 mm) was significantly greater than right (0.2 ± 0.1 mm) AIT (P = 0.03), and left AIT was marginally greater than in infants (P = 0.07). Among adults, with the exception of the appendage region, left AIT (1.0 ± 0.2 mm) was markedly greater than right AIT (0.3 ± 0.1 mm; P < 0.05), and left AIT was significantly greater than that in other age groups (P < 0.05). There were no differences in right AIT among age groups. Left intimal collagen bundle thickness was greater in adults (0.0512 ± 0.0056 µm) than infants (0.0432 ± 0.0071 µm) or children (0.0435 ± 0.0013 µm), and bundles were less organized. Wall stiffness was attributable primarily to the intima (1245 ± 132, vs. 260 ± 45 N/m(2) for the remaining atrial wall).CONCLUSION: The left atrial intima, but not the right, thickens with age, becomes more disorganized ultrastructurally, and is responsible for the majority of atrial wall stiffness.Europace 04/2013; · 2.77 Impact Factor
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ABSTRACT: The aim of this study was to analyze the therapeutic effects of various methods for the treatment of chronic atrial fibrillation (AF). Randomized controlled trials (RCT) concerning drug therapy and catheter ablation for the treatment of chronic AF were retrieved. The RevMan 5.1 software package was used for the meta-analysis. A total of 20 papers were assessed in this study. The results of the analysis indicated that the success rate was lower [odds ratio (OR), 8.94; 95% confidence interval (CI), 4.70-17.02; P<0.0001] and the relapse rate was higher (OR, 0.07, 95% CI, 0.05-0.10; P<0.0001) for drug therapy compared with that for catheter ablation. With regard to different catheter ablation procedures, the success rate for pulmonary vein antrum isolation (PVAI) was lower compared with that for PVAI plus complex fractionated atrial electrogram (CFAE; OR, 0.53; 95% CI, 0.37-0.78; P=0.0001). Pulmonary vein isolation (PVI) plus left atrial ablation (LAA) had a higher success rate compared with PVI alone (OR, 2.79; 95% CI, 1.59-4.88, P=0.0003). There was not identified to be a significant difference in the success rates between PVAI and CFAE (OR, 2.05; 95% CI, 0.06-205.74; P=0.76) or between PVI and circumferential pulmonary vein isolation (CPVI; OR, 0.94; 95% CI, 0.29-3.00; P=0.91). All the funnel plots of publication bias were essentially symmetrical. In conclusion, the success rate was higher and the relapse rate was lower for catheter ablation compared with drug therapy. Among the different procedures of catheter ablation, there were no significant differences in success rate between two single procedures; however, the success rates were higher for the combined methods compared with those for the single methods.Experimental and therapeutic medicine 08/2013; 6(2):489-496. · 0.34 Impact Factor
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ABSTRACT: The aim of this study was to investigate the correlation between the altered expression of genes involved in the regulation of ion channels in atrial myocytes and the risk of atrial fibrillation (AF) in patients with heart failure (HF). Right atrial appendages were obtained from 18 HF patients and 18 patients with normal cardiac functions who had undergone surgery. The mRNA expression levels of Kv4.3α, KvLQT1, Kv1.5, L-Caα1c and NCX were measured by reverse transcription-PCR (RT-PCR). Protein expression levels were also detected by western blotting. In comparison with the control group exhibiting normal cardiac functions, the mRNA and protein expression levels of Kv4.3α, KvLQT1 and L-Caα1c were significantly reduced in HF patients. By contrast, the mRNA and protein expression levels of NCX were significantly increased in HF patients compared with the control group (P<0.01). The mRNA expression levels of Kv1.5 were not evidently altered. We demonstrated that increased levels of Kv4.3α, KvLQT1 and L-Caα1c and decreased levels of NCX are correlated with the risk of AF in HF patients. Changes in the gene expression of ion channel-related proteins may therefore be used as biological markers of AF occurring in HF patients in future studies.Experimental and therapeutic medicine 04/2013; 5(4):1239-1243. · 0.34 Impact Factor