OBJECTIVEElectrical restitution was believed to be a determinant responsible for the stability of heart rhythm. Although numerous studies focused on the role of action potential duration restitution (APDR) in the initiation and maintenance of ventricular fibrillation (VF), the relationship between atrial APDR and atrial fibrillation (AF) has not been fully understood. This study aims to investigate the characteristics of APDR of left atrium (LA) and right atrium (Rs) in canines and the relevance to induction of AF.

METHODSMonophasic action potential (MAP) was recorded from LA and RA in 14 canines using the MAP recording-pacing combination catheter. APDR, plotted as action potential duration (APD) on the preceding diastolic interval (DI), was assessed by use of programmed stimulation with a single extrastimulus (S1S2) at LA and RA. Episodes of AF were recorded and analyzed.

RESULTSAPD90 was significantly shorter in the LA than that in the RA [(157.4 +/- 43.5) ms vs. (170.9 +/- 37.9) ms, P < 0.05]. The mean slope of the APDR curve by S1S2 in the LA was significantly greater than that in the RA (1.3 +/- 0.4 vs. 0.9 +/- 0.3, P < 0.05). The incidence of induced AF was significantly higher in the LA than in the RA (11/18 vs. 7/18, P < 0.05).

CONCLUSIONSThe APDR and MAP characteristics are not uniform between atrium, which may be one of the important mechanisms responsible for the initiation of AF. Heterogeneity of APDR between LA and RA might create critical gradients or a dispersion of repolarization and substrate for re-entrant arrhythmias and vulnerability to AF.

Action Potentials ; Animals ; Atrial Fibrillation ; etiology ; physiopathology ; Atrial Function, Left ; physiology ; Atrial Function, Right ; physiology ; Cardiac Pacing, Artificial ; Dogs ; Electric Countershock

BACKGROUNDIn the early stages of atrial remodeling, aortic stiffness might be an indication of an atrial myopathy, in particular, atrial fibrosis. This study aimed to investigate the association between left atrial (LA) mechanical function, assessed by two-dimensional speckle tracking echocardiography, and aortic stiffness in middle-aged patients with the first episode of nonvalvular atrial fibrillation (AF).

METHODSThis prospective study included 34 consecutive patients with the first episode of AF, who were admitted to Kartal Koşuyolu Research and Training Hospital between May 2013 and October 2015, and 31 age- and gender-matched healthy controls. During the 1 st month (mostly in the first 2 weeks) following their first admission, 34 patients underwent the first pulse wave measurements. Then, 21 patients were recalled for their second pulse wave measurement at 11.8 ± 6.0 months following their initial admission. Echocardiographic and pulse wave findings were compared between these 34 patients and 31 healthy controls. We also compared the pulse wave and echocardiographic findings between the first and second measurements in 21 patients.

RESULTSPulse wave analysis showed no significant differences between the AF patients and healthy controls with respect to PWV (10.2 ± 2.5 m/s vs. 9.7 ± 2.1 m/s; P = 0.370), augmentation pressure (9.6 ± 7.4 mmHg vs. 9.1 ± 5.7 mmHg; P = 0.740), and aortic pulse pressure (AoPP; 40.4 ± 14.0 mmHg vs. 42.1 ± 7.6 mmHg, P = 0.550). The first LA positive peak of strain was inversely related to the augmentation pressure (r = -0.30; P = 0.02) and aortic systolic pressure (r = -0.26, P = 0.04). Comparison between the two consecutive pulse wave measurements in 21 patients showed similar results, except for AoPP. In 21 patients, the AoPP at the second measurement (45.1 ± 14.1 mmHg) showed a significant increase compared with AoPP at the first measurement (39.0 ± 10.6 mmHg, P = 0.028), which was also higher than that of healthy controls (42.1 ± 7.6 mmHg, P = 0.000).

CONCLUSIONThe association between aortic stiffness with reduced atrial strain and the key role of AoPP in the development of AF should be considered when treating nonvalvular AF patients with normal LA sizes.

Adult ; Atrial Fibrillation ; physiopathology ; Atrial Function, Left ; physiology ; Atrial Remodeling ; physiology ; Echocardiography ; Female ; Humans ; Male ; Middle Aged ; Prospective Studies ; Vascular Stiffness ; physiology

PURPOSE: The effect of radiofrequency catheter ablation (RFCA) on left atrial (LA) volume and function in patients with paroxysmal atrial fibrillation (PAF) has not been extensively studied. The aim of this study was to evaluate the long-term impact of RFCA on LA volume and function in patients with PAF. MATERIALS AND METHODS: A total of 90 patients with drug-refractory PAF who had sinus rhythm on the initial echocardiogram were examined at baseline, 3 months and 1 year after ablation. We measured LA volume index, LA ejection fraction (LAEF; maximal-minimal LA volume/maximal LA volume), and LA active emptying fraction (LAAEF; mid-diastolic-minimal LA volume/mid-diastolic LA volume). RESULTS: After 12+/-1 months, 78 patients returned, and 61 patients (78%) had sinus rhythm. After 3 months, the LA maximal volume indices decreased (from 33+/-13 to 28+/-12 mL/m2; p<0.001). But, LAEF and LAAEF also decreased (from 48+/-13 to 39+/-12; p<0.001, from 27+/-13 to 19+/-11; p<0.001). After 1 year, LA volumes, LAEF, and LAAEF remained similar at 3 months. In patients without atrial fibrillation (AF) recurrence, LAEF and LAAEF decreased after 3 months (from 50+/-12 to 40+/-11; p<0.001, from 29+/-13 to 22+/-11; p<0.001) and did not change after 1 year. However, in patients with AF recurrence, those who did not have decreased levels after 3 months had significantly decreased after 1 year (from 43+/-14 to 34+/-11; p=0.026, from 22+/-12 to 15+/-10; p=0.012). CONCLUSION: Successful RFCA of PAF decreased LA volume and function at 3 months. At one year, LA volume and function was remained unchanged in successfully ablated patients whereas LA function in patients with AF recurrence worsened.
Adult ; Aged ; Atrial Fibrillation/*therapy ; Atrial Function, Left/*physiology ; *Catheter Ablation ; Echocardiography ; Female ; Humans ; Male ; Middle Aged ; Retrospective Studies

PURPOSE: The effect of radiofrequency catheter ablation (RFCA) on left atrial (LA) volume and function in patients with paroxysmal atrial fibrillation (PAF) has not been extensively studied. The aim of this study was to evaluate the long-term impact of RFCA on LA volume and function in patients with PAF. MATERIALS AND METHODS: A total of 90 patients with drug-refractory PAF who had sinus rhythm on the initial echocardiogram were examined at baseline, 3 months and 1 year after ablation. We measured LA volume index, LA ejection fraction (LAEF; maximal-minimal LA volume/maximal LA volume), and LA active emptying fraction (LAAEF; mid-diastolic-minimal LA volume/mid-diastolic LA volume). RESULTS: After 12+/-1 months, 78 patients returned, and 61 patients (78%) had sinus rhythm. After 3 months, the LA maximal volume indices decreased (from 33+/-13 to 28+/-12 mL/m2; p<0.001). But, LAEF and LAAEF also decreased (from 48+/-13 to 39+/-12; p<0.001, from 27+/-13 to 19+/-11; p<0.001). After 1 year, LA volumes, LAEF, and LAAEF remained similar at 3 months. In patients without atrial fibrillation (AF) recurrence, LAEF and LAAEF decreased after 3 months (from 50+/-12 to 40+/-11; p<0.001, from 29+/-13 to 22+/-11; p<0.001) and did not change after 1 year. However, in patients with AF recurrence, those who did not have decreased levels after 3 months had significantly decreased after 1 year (from 43+/-14 to 34+/-11; p=0.026, from 22+/-12 to 15+/-10; p=0.012). CONCLUSION: Successful RFCA of PAF decreased LA volume and function at 3 months. At one year, LA volume and function was remained unchanged in successfully ablated patients whereas LA function in patients with AF recurrence worsened.
Adult ; Aged ; Atrial Fibrillation/*therapy ; Atrial Function, Left/*physiology ; *Catheter Ablation ; Echocardiography ; Female ; Humans ; Male ; Middle Aged ; Retrospective Studies

Action Potentials ; Animals ; Atrial Fibrillation ; physiopathology ; Atrial Function, Left ; physiology ; Cardiac Pacing, Artificial ; Pulmonary Veins ; physiology ; Rabbits ; Streptomycin ; pharmacology ; Verapamil ; pharmacology

BACKGROUND AND PURPOSE: Left atrial dysfunction has been reported in patients with patent foramen ovale (PFO). Here we investigated the role of left atrial dysfunction in the development of embolic stroke in patients with PFO. METHODS: We identified consecutive patients with embolic stroke of undetermined sources except for PFO (PFO+ESUS). Healthy subjects with PFO served as controls (PFO+control). A stratified analysis by 10-year age group and an age- and sex- matching analysis were performed to compare echocardiographic markers between groups. In the PFO+ESUS group, infarct patterns of PFO-related stroke were determined (cortical vs. cortico-subcortical) and analyzed in correlation with left atrial function parameters. RESULTS: A total of 118 patients and 231 controls were included. The left atrial volume indices (LAVIs) of the PFO+ESUS patients were higher than those of the PFO+controls in age groups of 40–49, 50–59, and 60–69 years (P<0.001, P=0.003, and P=0.027, respectively), and in the age- and sex-matched analysis (P=0.001). In the PFO+ESUS patients, a higher (>28 mL/m2) LAVI was more associated with the cortical infarct pattern (P=0.043 for an acute infarction and P=0.024 for a chronic infarction, both adjusted for age and shunt amount). The degree of right-to-left shunting was not associated with infarct patterns, but with the posterior location of acute infarcts (P=0.028). CONCLUSIONS: Left atrial enlargement was associated with embolic stroke in subjects with PFO. Left atrial physiology might contribute to the development of PFO-related stroke and need to be taken into consideration for optimal prevention of PFO-related stroke.
Atrial Function, Left ; Echocardiography ; Embolism ; Embolism, Paradoxical ; Foramen Ovale, Patent* ; Healthy Volunteers ; Heart Atria ; Humans ; Infarction* ; Physiology ; Stroke

This study was designed to obtain new parameters representing left ventricular (LV) function independent of irregular RR intervals in atrial fibrillation (AF). AF patients were divided into Normal (n=9) and LV Dysfunction (n=9) groups. The relations between LV outflow peak ejection velocity (Vpe) and preceding (RR-1) or prepreceding RR intervals (RR-2) were obtained using logarithmic equations, from which the squared correlation coefficient (r2), slope, Vpe at RR-1 or RR-2=1 sec (Vpe-1), and the ratio of slope to Vpe-1 (Slope/Vpe-1) were calculated. Among the parameters between RR-1 and Vpe, Slope/Vpe-1 was higher in LV Dysfunction group than in Normal group (p=0.05). When only coordinates with RR-1 from 0.6 to 1 sec were included, Slope/Vpe-1 (p=0.001) was higher in LV Dysfunction group than in Normal group. Among the parameters between RR-2 and Vpe, Slope/Vpe-1, slope, and r2 were different between the two groups. In multivariate analysis, Slope/Vpe-1 between RR-2 and Vpe was only independent parameter. However, Slope/Vpe-1 between RR-1 and Vpe in the coordinates with RR-1 from 0.6 to 1 sec had the highest discriminating power. New parameters derived from the relations between RR intervals and LV performance might be useful to evaluate LV function quantitatively in AF.
Age Factors ; Aged ; Atrial Fibrillation/*metabolism ; Atrial Function, Left ; Echocardiography ; Echocardiography, Doppler, Pulsed ; Electrocardiography ; Female ; Heart/physiology ; Heart Ventricles ; Hemodynamic Processes ; Humans ; Male ; Middle Aged ; Models, Theoretical ; Multivariate Analysis ; Myocardial Contraction ; Myocardium/pathology ; Time Factors ; *Ventricular Function, Left

PURPOSE: The Maze procedure has shown excellent efficacy in the elimination of atrial fibrillation (AF); however, little is known about the quality of functional recovery in the left atrium (LA) following successful sinus rhythm conversion by the Maze procedure. MATERIALS AND METHODS: We prospectively enrolled 12 patients (aged 52.5+/-10.1 years, 1 female) with valvular AF undergoing mitral valve surgery combined with the Maze procedure. Parameters of LA function in three anatomic compartments [anterior, posterior, and LA appendage (LAA)] were evaluated using electrocardiography-gated dual-source cardiac CT at one month and at six months after surgery. Twelve subjects matched by age, gender, and body surface area served as controls. RESULTS: At one month after surgery, ejection fraction (EF) and emptying volume (EV) of the LA were 14.9+/-7.4% and 21.3+/-9.7 mL, respectively, and they were significantly lower than those of the control group (EF, 47.9+/-11.2%; EV, 46.0+/-10.7%; p<0001). These values did not significantly change throughout late periods (p=0.22 and 0.21, respectively). Functional contributions of the anterior, posterior, and appendage compartments (EV of each compartment/overall EV) were 80.4%, -0.9%, and 20.5%, respectively, for those with LAA preservation (n=6); 100.1%, -0.1%, and 0% for those with LAA resection (n=6; p<0.05); and 62.2%, 28.2%, and 9.7% in the control subjects (p<0.001). CONCLUSION: Contractile functions of the LA significantly decreased after the Maze procedure. Functional contributions of three compartments of the LA were also altered. The influence of LAA preservation on postoperative LA functions needs to be evaluated through studies of larger populations.
*Ablation Techniques ; Adult ; Aged ; Atrial Appendage/*physiopathology ; Atrial Fibrillation/physiopathology/*surgery ; Atrial Function, Left/*physiology ; Case-Control Studies ; Electrocardiography/methods ; Female ; Heart Atria ; Humans ; Male ; Middle Aged ; Prospective Studies ; Recovery of Function ; Tomography, X-Ray Computed

Atrial Function, Left ; physiology ; Echocardiography, Three-Dimensional ; methods ; Female ; Heart Atria ; diagnostic imaging ; Humans ; Male ; Mitral Valve ; diagnostic imaging ; Stroke Volume ; physiology

In atrial fibrillation, cardiac performance is dependent on both preceding RR (RR-1) and prepreceding RR (RR-2) intervals. However, relative contributions were not well defined. Left ventricular outflow peak ejection velocity (Vpe) was measured by echocardiography from 21 patients. The relation between RR-1 and Vpe could be divided into two zones; steep slope in short RR-1 intervals ( 0.5 sec). RR-2 had a weak negative association with Vpe. The mean squared correlation coefficient (r2 ) between RR-2 and Vpe was 0.15 +/-0.13 and improved to 0.29 +/-0.21 (p<0.001), when coordinates with RR-1 function was impaired.
Aged ; Aged, 80 and over ; Atrial Fibrillation ; *Atrial Function, Left ; Echocardiography, Doppler, Pulsed/*methods ; Electric Countershock ; Electrocardiography/*methods ; Female ; Heart/*physiology ; Heart Ventricles ; Humans ; Male ; Middle Aged ; Myocardium/pathology ; Time Factors