Cardioversion Of Chronic Atrial Fibrillation Research Articles

Computer simulation of the role of fibre orientation in cardioversion of chronic atrial fibrillation

Computer simulation of the role of fibre orientation in cardioversion of chronic atrial fibrillation

Digitalis Does not Improve Left Atrial Mechanical Dysfunction After Successful Electrical Cardioversion of Chronic Atrial Fibrillation

This study was designed to investigate whether administration of digitalis could improve mechanical function of left atrial appendage (LAA) and left atrium prospectively in patients with atrial stunning. Fifty-four consecutive patients in whom atrial stunning was observed immediately after cardioversion of chronic atrial fibrillation (AF) were randomized into digitalis or control group for 1 week following cardioversion. Transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) were performed prior to, immediately following, 1 day after and 1 week after cardioversion to measure transmitral flow velocity and LAA flow velocity. Electrical cardioversion of AF elicited significantly slower left atrial appendage peak emptying velocity (LAA-PEV) and peak filling velocity (LAA-PFV) immediately following cardioversion in both groups. 1 day post cardioversion, there were no significant differences in transmitral E wave, A wave, E/A ratio, LAA-PEV, LAA-PFV or left atrial appendage ejection fraction (LAA-EF) between digitalis and control groups. 1 week post cardioversion, no significant differences were found in transmitral E wave, A wave, E/A ratio, LAA-PEV, LAA-PFV or LAA-EF between the two groups. The occurrence rates of spontaneous echo contrast were not significantly different between digitalis and control groups one day and one week post cardioversion. In conclusion, digitalis did not improve left atrial and appendage mechanical dysfunction following cardioversion of chronic AF. Digitalis did not prevent the development of spontaneous echo contrast in left atrial chamber and appendage. This may be due to the fact that digitalis aggravates intracellular calcium overload induced by chronic AF and has a negative effect on ventricular rate.

LASER DOPPLER FLUXMETRY

Laser Doppler fluxmetry (LDF) is an extraordinary sensitive noninvasive method of examination. It can be used for monitoring changes in the cutaneous peripheral microcirculation(15). It uses a monochromatic low-energy laser beam. This beam penetrates the tissue and, depending on individual tissue penetration, it is reflected, recorded by a sensitive sensor and subsequently analyzed using the Doppler. Laser Doppler fluxmetry detects movement of cells in the peripheral circulation and microcirculation. The light from the laser source is delivered via optical fibers to the tissue. In the tissue the light collides with moving blood elements; after a collision, the wave length of the light changes--this phenomenon is called Doppler shift. Our own method of measurement has already been fully developed. We have a group of patients with physiological findings and also groups of patients with vasoneurosis, patients with type 1 diabetes mellitus, vasculitis patients, and other patient groups. We examine the blood flow on the dorsal side of fingers or toes. There are many protocols for laser Doppler examination. For all the patient groups we used a protocol evaluating an algorithm, developed in the training department of the Perimed company, using provocation tests for the assessment of the vascular wall function in addition to records at rest. USE OF LASER DOPPLER: We have developed a method of use of laser Doppler examination in about 8 years. We have examined several groups of patients. First a patient group with physiological findings was examined, and subsequently groups of patients with vasculitis, vasoneurosis, and a group of patients with type l diabetes mellitus. Recently, monitoring has been performed in patients after cardioversion in chronic atrial fibrillation with sinus rhythm restitution, and also data obtained before and after a varicose vein operation on lower limbs have been compared. Clear diagnostic criteria for this method do not exist so far. For the time being this is a rather theoretical method that we used even in practice for the above mentioned diseases. The method provides enough data even for more detailed analyses. The information value of the curve arises after statistical data analysis with the t-test.

Segmental atrial contraction in patients restored to sinus rhythm after cardioversion for chronic atrial fibrillation: A colour Doppler tissue imaging study

There is little known about segmental atrial function in patients with atrial arrhythmias. We evaluated segmental atrial contractility using colour Doppler tissue imaging (CDTI) in patients with chronic atrial fibrillation (CAF) who were successfully restored and maintained in sinus rhythm (SR). We compared the segmental atrial contractility in 39 CAF patients who were successfully cardioverted and maintained in SR for 6 months. Follow up echocardiograms were performed at baseline, 1 week, 1 month and 6 months and compared to a normal age matched cohort (n = 34). Using CDTI, mean peak velocities of atrial contraction were measured from annular, mid and superior segments of lateral and septal walls of the left atrium and right atrium in the apical four-chamber view. Segmental velocities from the posterior and anterior walls of the left atrium were measured from the apical two-chamber view. Segmental left atrial velocities improved over time in the CAF group, with the majority of the recovery occurring in the first month, but failed to normalise even at 6 months. In comparison, the right atrial velocities in the AF group had normalised at 1 month. Patients with CAF have persistent segmental left atrial dysfunction even 6 months after restoration and maintenance of SR, though right atrial velocities appear to normalise. This differential recovery indicates that left atrial function remains subnormal in patients with CAF despite maintenance of SR, suggesting underlying atrial myopathy or fibrosis as a consequence of CAF.

A novel rectangular biphasic waveform from a radio frequency defibrillator compared with a conventional waveform for the transvenous cardioversion of chronic atrial fibrillation in patients

A novel rectangular biphasic waveform from a radio frequency defibrillator compared with a conventional waveform for the transvenous cardioversion of chronic atrial fibrillation in patients

A novel rectangular biphasic waveform from a radiofrequency defibrillator compared with a conventional waveform for the transvenous cardioversion of chronic atrial fibrillation in patients

of 195 (PEM, standard) ECG pairs; and (b) 24 ambulatory cardiac patients recorded during their routine visit at the cardiology hospital of Lyon. Both the standard and the derived 12-lead ECGs have been reprocessed by the Lyon Program. A quantitative comparison of the computerized global and lead-by-lead measurements was performed on data set a (Table 1), and a qualitative comparison was made on data set b (Table 2) by a cardiologist who blindly analyzed, in measurements and interpretation, the 2 derived ECGs with reference to the standard 12-lead ECG. In conclusion, the patient-specific transform provides better results, similar to the Mason-Likar lead system.

Effect of IKr Blocker Nifekalant on Atrial Action Potential Duration After Successful Internal Cardioversion of Chronic Atrial Fibrillation

Chronic atrial fibrillation (AF) is characterized by a marked decrease in the atrial effective refractory period (ERP) and in the ERP adaptation to rate as well as a decrease in the atrial conduction velocity. Little information is available about the ionic mechanisms underlying AF in humans. We studied the effect of IKr blocker nifekalant on the rate-dependent changes in atrial action potential duration in 11 patients after successful internal cardioversion of chronic AF of >2 months duration and in 7 patients without AF. In AF patients, right atrial (RA) monophasic action potential (MAP) was recorded at pacing cycle lengths (CLs) of 800-250 ms before and after administration of nifekalant. In control patients, RAMAP was recorded at CLs of 600 and 350 ms before and after administration of nifekalant. Nifekalant significantly increased RAMAPD at 90% repolarization (RAMAPD90) at CLs of 800-300 ms in the AF patients. The increase in RAMAPD90 by nifekalant became significantly smaller at shorter CLs (42.5 +/- 12.4 ms at a CL of 600 ms vs 32.8 +/- 14.5 ms at a CL of 350 ms, P < 0.05). Effect of nifekalant on RAPMAPD was attenuated at CL of 600 ms in AF patients in comparison to control patients (increase in RAMAPD in control; 73.0 +/- 36.6 ms vs increase in RAMAPD in AF; 42.5 +/- 12.4 ms, P < 0.05); however, it was similar at a CL of 350 ms between control and AF patients. Electrophysiological effects of nifekalant are significantly attenuated in the chronically remodeled human atrium at slower heart rates, but the beneficial effect of RAMAPD prolongation by IKr blocker was well-preserved even at shorter CLs after chronic AF.

Efficacy of internal cardioversion for chronic atrial fibrillation in patients with and without left ventricular dysfunction

Internal cardioversion can restore sinus rhythm with energies below 6–10 J, often without anaesthesia/sedation. We investigated its safety and short-/medium-term efficacy in patients with persistent atrial fibrillation (AF) with left ventricular dysfunction (defined as ejection fraction ≤40%). Among 34 patients with persistent AF who agreed to receive internal cardioversion, 16 had left ventricular dysfunction and 18 did not (the groups were similar as regards age, duration of AF and pretreatment with amiodarone). Internal CV was performed delivering 3.0/3.0-ms biphasic shocks between coil catheters using a step-up protocol. Sinus rhythm was always restored. General anaesthesia (administered only when discomfort was not tolerated) was required only in 2 of the 16 (12.5%) patients with left ventricular dysfunction. The defibrillation threshold was similar in patients with and without left ventricular dysfunction (10.2±6.9 vs. 8.4±4.9 J; p=0.37). Short-term (within 72 h) AF recurrence rates in the presence and absence of left ventricular dysfunction were 19% (3/16) and 6% (1/18), respectively ( p=0.51). After cardioversion, all patients received antiarrhythmic drugs (mostly amiodarone in patients with left ventricular dysfunction and class IC agents in the remainder). With mean follow-up periods of about 220 days, AF recurrence rates among patients with and without left ventricular dysfunction were 50% (8/16) and 28% (5/18), respectively ( p=0.328). We conclude that even in patients with left ventricular dysfunction, internal CV is safe and effective, minimizing risks from anaesthesia. Although these patients may have a higher risk of short- or medium-term AF recurrence, 6-month maintenance of sinus rhythm is possible in about 50% of cases.

1129-211 Cardioversion of chronic atrial fibrillation is associated with an immediate drop in brain natriuretic peptide

1129-211 Cardioversion of chronic atrial fibrillation is associated with an immediate drop in brain natriuretic peptide

Comparison of left atrial volume and function after linear ablation and after cardioversion for chronic atrial fibrillation

Several techniques for treatment of atrial fibrillation (AF) have been developed, including the direct placement of radiofrequency for lesions at open heart surgery. Detailed evaluation of left atrial (LA) function has not been performed after these procedures and has not been compared in patients with chronic AF. We compared the atrial function of patients with sustained sinus rhythm (SR) after linear ablation with a group who underwent direct-current cardioversion and a group of normal controls to investigate the measurable deleterious effects, if any, on atrial function after the surgical procedure. Twenty-one consecutive patients who had maintained SR for >6 months after a linear radiofrequency ablation (LRFA) procedure were studied. As control subjects, we examined 33 patients with chronic AF successfully restored to SR by cardioversion who maintained SR for >6 months and 42 age-matched normal subjects. LA function was decreased in both the LRFA and cardioverted AF groups compared with normal controls. The parameters of LA function, atrial fraction, LA ejection fraction, and the A′ velocity were lowest in the LRFA group, intermediate in the cardioverted AF group, and highest in the normal controls (LA function: 15.8 ± 10%, 26 ± 10%, 33 ± 7%; p = 0.0001; LA ejection fraction: 31 +13%, 41 ± 12%, 51 ± 9%; p = 0.0001; A′ velocity: 4.2 ± 1.4, 7.6 ± 2.2, 9.5 ± 1.9 cm/s; p = 0.0001). LA volumes were increased in the LRFA and cardioverted AF groups compared with normals (62.8 ± 22 vs 70.6 ± 17 vs 38.7 ± 9.8 ml; p = 0.0001). Thus, although LA function is restored and maintained after LRFA has been performed during open heart surgery, LRFA use is associated with a measurable decrease in LA function over and above that found after conventional cardioversion.

P-310 Evaluation of effects of antiarrhythmic therapy on left ventricular performance by tissue doppler echocardiography during follow-up after cardioversion of chronic atrial fibrillation

P-310 Evaluation of effects of antiarrhythmic therapy on left ventricular performance by tissue doppler echocardiography during follow-up after cardioversion of chronic atrial fibrillation

P-310 Evaluation of effects of antiarrhythmic therapy on left ventricular performance by tissue doppler echocardiography during follow-up after cardioversion of chronic atrial fibrillation

P-310 Evaluation of effects of antiarrhythmic therapy on left ventricular performance by tissue doppler echocardiography during follow-up after cardioversion of chronic atrial fibrillation

Atrial stunning: Determinants and cellular mechanisms

BackgroundAtrial stunning is a transient depression of atrial and atrial-appendage mechanical function after successful cardioversion of atrial fibrillation compared with its precardioversion state. MethodAtrial stunning associated with different methods of cardioversion of atrial fibrillation and the determinants and cellular mechanisms of atrial stunning were elaborated by thoroughly examining the studies on the subject identified through a comprehensive literature search. Results and conclusionAtrial stunning has been reported with all methods of cardioversion of atrial fibrillation, including transthoracic electrical, low-energy internal electrical, pharmacological, and spontaneous. It is a function of the underlying atrial fibrillation becoming apparent at the restoration of sinus rhythm, regardless of the method used for conversion. Unsuccessful cardioversion does not result in atrial stunning. The duration of the preceding atrial fibrillation, atrial size, and underlying structural heart disease are the determinants of atrial stunning. A shorter duration of atrial fibrillation and smaller atrial diameters are associated with a relatively less severe stunning, lasting for a shorter duration. Atrial stunning after cardioversion of atrial fibrillation of <1 week usually resolves within 24 hours, and atrial stunning after cardioversion of chronic atrial fibrillation usually resolves within 4 weeks. Tachycardia-induced atrial cardiomyopathy, atrial cytosolic calcium alterations with down-regulation of the L-type Ca2+ channels and up-regulation of the Na+/Ca2+ exchanger, atrial hibernation with myocyte dedifferentiation and myolysis, and atrial fibrosis are the suggested mechanisms underlying atrial stunning. Atrial stunning determines the risk of postcardioversion thrombus formation in atria and atrial appendages, the duration of postcardioversion anticoagulation therapy, the recovery of the atrial contribution to the ventricular function, and the functional recovery of the patients after successful cardioversion of atrial fibrillation.

Effect of low-dose isoproterenol infusion on left atrial appendage function soon after cardioversion of chronic atrial tachyarrhythmias

Background: Cardioversion of chronic atrial fibrillation or atrial flutter to sinus rhythm is often associated with transient atrial mechanical dysfunction, i.e. ‘atrial stunning’, which may increase the risk of subsequent thromboembolic events. We hypothesized that, because of its positive inotropic action, a low-dose isoproterenol infusion might improve postcardioversion atrial mechanical function. Method: Eighteen patients (15 male, three female; 12 atrial fibrillation, six atrial flutter; mean age 65±10 years) exhibiting atrial postcardioversion stunning were included in the study. Isoproterenol was infused for 10 min at a dose sufficient to increase the heart rate by about 10%. Using transesophageal echocardiography, both the left atrial appendage emptying/filling flow velocity and function (fractional area change) were examined at baseline, before isoproterenol (immediately after cardioversion) and after isoproterenol. Results: With infusion of 0.005–0.008 μg/kg/min isoproterenol, heart rate increased by 11.1±2.9%, and left atrial appendage emptying velocity, which was diminished following cardioversion, increased significantly ( P<0.001) (baseline, before and after isoproterenol: 41.1±18.0, 20.3±8.5 and 27.3±9.6 cm/s, respectively). No major complications were associated with isoproterenol infusion. Conclusions: Short-term infusion of low-dose isoproterenol improved atrial function after cardioversion of chronic atrial fibrillation and atrial flutter.

Reduction of left atrial stretch facilitates internal cardioversion of chronic atrial fibrillation in patients undergoing percutaneous balloon mitral valvuloplasty for mitral stenosis Katherine Fan, Kathy L. Lee, Wing Hing Chow, Elaine Chau, On Hing Kwok, Chu Pak Lau. Grantham Hospital, Hong Kong, Hong Kong

Reduction of left atrial stretch facilitates internal cardioversion of chronic atrial fibrillation in patients undergoing percutaneous balloon mitral valvuloplasty for mitral stenosis Katherine Fan, Kathy L. Lee, Wing Hing Chow, Elaine Chau, On Hing Kwok, Chu Pak Lau. Grantham Hospital, Hong Kong, Hong Kong

Short-term hemodynamic effects of sinus rhythm restoration by internal cardioversion in chronic atrial fibrillation

Short-term hemodynamic effects of sinus rhythm restoration by internal cardioversion in chronic atrial fibrillation

Short-term hemodynamic effects of sinus rhythm restoration by internal cardioversion in chronic atrial fibrillation

Short-term hemodynamic effects of sinus rhythm restoration by internal cardioversion in chronic atrial fibrillation

Changes in atrial electrical properties following cardioversion of chronic atrial fibrillation: relation with recurrence.

To study the reversibility of atrial electrical remodeling and its relation with recurrence in post-conversion chronic atrial fibrillation (CAF) patients. In 28 drug-free CAF patients (mean AF duration 41+/-39 months) electrically converted to sinus rhythm effective refractory period (ERP) at 500 ms, monophasic action potential at 90% of repolarization (MAPd90) at five cycle lengths (CL, 350, 400, 450, 500, 600 ms), and P wave duration were measured three times: within the interval 5-20 min post-conversion, 24 h and 1 month later. Fifteen subjects with no history of AF and normal atrial structure served as a control group. Patients were followed up for recurrence for 1 month; 12 relapsed. ERP changed from 205+/-20 to 243+/-31 to 241+/-24 ms (P<0. 001), attaining a level comparable to that of the controls (238+/-21 ms) within 24 h. MAPd90 significantly (P<0.001) increased (from 175+/-11 to 190+/-19 to 191+/-10 ms at CL 350 ms and 201+/-12 to 234+/-20 and 233+/-23 ms at CL 600 ms) also reaching control levels within 24 h. MAPd90 exhibited an abnormal adaptation to rate only in the first evaluation. P wave duration was prolonged (137+/-33 ms) and exhibited a slower course of shortening (130+/-32 to 123+/-27 ms, P<0.001), reaching control levels within 1 month. Patients with higher values of MAPd90 at CL 350 in the immediate post-conversion period were more likely to relapse (P<0.005). ERP and repolarization shortening as a result of CAF are reversed within 24 h after conversion, while P wave duration reduces more slowly. Post-conversion MAPd90 values contain prognostic information for recurrence.

Role of atrial pressure in the success of electrical cardioversion of chronic atrial fibrillation

Chronic persistent atrial fibrillation (AF) accounts for increased morbidity and mortality because of its associated risk for embolic events and its negative impact on cardiac function.1–3 For these reasons, chemical and electrical cardioversion are commonly considered in the management of patients with this arrhythmia. Transthoracic electrical cardioversion is the most widely used method for restoring sinus rhythm; the reported success rate ranges between 67% and 94%, which means that about 20% of patients cannot be converted to sinus rhythm.4,5 The duration of AF is the most reliable and powerful predictor of the success of cardioversion6,7 There are also other predictors, such as the etiology of AF, age, and left atrial diameter. However, to our knowledge, it has not yet been shown whether there was a relation between the success of external electrical cardioversion and patients’ hemodynamic status. In the present study we assessed the clinical, echocardiographic, and hemodynamic variables to predict the acute success of electrical cardioversion of chronic persistent AF.

Intravenous sotalol decreases transthoracic cardioversion energy requirement for chronic atrial fibrillation in humans: assessment of the electrophysiological effects by biatrial basket electrodes

OBJECTIVESThis study was undertaken to assess the effects of sotalol on the transthoracic cardioversion energy requirement for chronic atrial fibrillation (AF) and on the atrial electrograms during AF recorded by two basket electrodes.BACKGROUNDThe effects of sotalol infusion on transthoracic electrical cardioversion for chronic atrial fibrillation in humans have not been well investigated.METHODSWe included 18 patients with persistent AF for more than three months. Atrial electrograms were recorded by two basket electrodes positioned in each atrium respectively. Transthoracic cardioversion was performed before and after sotalol 1.5 mg/kg IV infusion.RESULTSIn the 14 patients whose AF could be terminated by cardioversion before sotalol infusion, the atrial defibrillation energy was significantly reduced after sotalol infusion (236 ± 74 jules [J] vs. 186 ± 77 J; p < 0.01). Atrial fibrillation was refractory to cardioversion in four patients at baseline and was converted to sinus rhythm by cardioversion after sotalol infusion in two of them. We further divided the patients into two groups. Group A consisted of 10 patients in whom the energy requirement was decreased by sotalol while group B consisted of eight patients in whom the energy requirement was not decreased. The mean A-A (atrial local electrogram) intervals during AF were significantly increased after sotalol infusion in both groups, but the increment of A-A interval was significantly larger in group A than it was in group B patients (36 ± 13 ms vs. 22 ± 8 ms for the right atrium; 19 ± 7 ms vs. 9 ± 7 ms for the left atrium; both p < 0.05). The spatial and temporal dispersions of A-A intervals were not significantly changed after sotalol infusion in both atria in both groups.CONCLUSIONSSotalol decreases the atrial defibrillation energy requirement by increasing atrial refractoriness but not by decreasing the dispersion of refractoriness.