Hemodynamic and cardiorespiratory function following internal atrial defibrillation for chronic atrial fibrillation

Internal atrial defibrillation (IAD) is able to restore sinus rhythm in patients with chronic atrial fibrillation (AF) and failed external electrical and/or pharmacologic cardioversion. To assess whether cardiorespiratory and hemodynamic function improve after IAD, 35 patients were prospectively investigated during constant workload exercise by spiroergometry and Doppler echocardiography before IAD, and 1 day and 1 month after IAD. Oxygen uptake kinetics, ventilation, left atrial mechanical function, and pulmonary artery pressure were determined simultaneously at rest and during steady state. During the serial follow-up, 20 patients maintained sinus rhythm. The time interval for achieving the steady state (146 ± 53 vs 132 ± 42 seconds; p = 0.5) and the oxygen deficit (645 ± 190 vs 670 ± 174 ml; p = 0.7) were not different before and 1 day after IAD, but decreased significantly after 1 month (98 ± 16 seconds, p = 0.01 and 487 ± 72 ml, p = 0.02). Exercise pulmonary artery systolic pressures were 38 ± 13 mm Hg before IAD, increased significantly to 46 ± 11 mm Hg on day 1 (p = 0.03), and decreased below baseline values at 1 month to 31 ± 12 mm Hg (p = 0.07). Peak A-wave velocities increased from 0.51 ± 0.1 m/s after 1 day to 0.67 ± 0.2 m/s after 1 month (p = 0.03). Restoration of sinus rhythm in patients with AF resistant to external electrical and/or pharmacologic cardioversion improves hemodynamic and cardiorespiratory function at daily activity exercise levels.     

Echocardiographic factors predictive of restoration and maintenance of sinus rhythm after reduction of atrial fibrillation

BACKGROUND: Atrial fibrillation (AF) is the most common cardiac arrhythmia. While the arrhythmia was initially thought to be little more than a nuisance, it is now clear that AF has a significant negative impact on quality of life and a corresponding increase in both morbidity and mortality. OBJECTIVE: The aim of this study was to identify Doppler echographic patterns that allow prediction of atrial fibrillation reduction and maintenance of sinus rhythm within 12 months. PATIENTS AND METHODS: One hundred and thirty patients having permanent atrial fibrillation, recent (51) or chronic (79) are included in the study, excepting those with valvular heart disease or thyroid dysfunction. The mean age was 63.5 +/- 11.3 years. Both transthoracic and transoesophageal echocardiography was performed using a Philips SONOS 5500 Echograph, before cardioversion. Were studied: end diastolic and systolic left ventricular diameters, left ventricular ejectionnal fraction, left atrial area (LAA), left atrial diameter, left atrial appendage area and peak emptying velocities of the left atrial appendage (PeV). Sinus rhythm was re-established in 102 patients (44 having recent and 58 chronic atrial fibrillation). Sinus rhythm was maintained for 12 months in 79 patients. RESULTS: Within the echographic parameters studied, the left atrial area (LAA) and peak emptying velocities of left atrial appendage (PeV) before cardioversion were the best predictors of restoration of sinus rhythm. On monovariate analysis, SOG is significantly lower and PicV is significantly higher in patients whose sinus rhythm had been restored in comparison with those with permanent atrial fibrillation. (Mean SOG: 27.7 +/- 7.62 vs. 34 +/- 7,6 cm2, p<0.0001; Mean PicV: 44 +/- 15.8 vs. 31.4 +/- 13,7 cm/s, p<0.0001). This difference was maintained on multivariate analysis (p=0.002 for SOG and p=0.005 for PicV). In patients with recent atrial fibrillation, only left atrial area can predict on mono and multivariate analysis (p=0.05, OR=0.5, IC=0.36 à 3.56), re-establishing of sinus rhythm whereas in patients with chronic atrial fibrillation, peak emptying velocity of left atrial appendage predict better re-establishing of sinus rhythm (p=0.04, OR=1.29, IC=0.12 à 4.23). The threshold values of LAA and PeV for conversion of atrial fibrillation into sinus rhythm are respectively 25 cm2 and 20 cm/sec. In patients who converted into sinus rhythm; LAA predict maintenance of sinus rhythm at the end of 12 months of survey (p=0.04) with a threshold value of 25 cm2. In the subgroup of patients admitted with chronic atrial fibrillation, PeV predicts better the maintenance of sinus rhythm (p=0.05) with a threshold value of 60 cm/sec, p=0.06; whereas LAA remains better in patients with a recent atrial fibrillation. (p=0.02). CONCLUSION: In addition to the anatomic study of cardiac structure and the search of intracavitary thromboses before reduction of atrial fibrillation, echocardiography allows prediction of cardioversion success (LAA and PeV) and maintenance of sinus rhythm within 12 months.     

Atrial Mechanical Function Before and After Electrical or Amiodarone Cardioversion in Atrial Fibrillation: Assessment by Transesophageal Echocardiography and Pulsed Doppler

In some patients with atrial fibrillation (AF), it has been suggested that left atrial mechanical dysfunction can develop after successful electrical cardioversion, justifying postcardioversion anticoagulant treatment. The purpose of this study was to investigate differences in left atrial appendage peak flow velocities and the incidence of left atrial spontaneous echo contrast in patients with AF before and after electrical cardioversion or intravenous amiodarone, studied using transesophageal echocardiography (TEE) and pulsed Doppler. We performed a control TEE in 7 patients in the electrical group and 6 in the amiodarone group, with no significant clinical differences between both groups. A second TEE was performed immediately in the 7 patients with successful electrical cardioversion. The peak flow velocities in the appendage before and after the procedure were: filling 43.3 ± 22 vs 27.7 ± 28 cm/sec (P = 0.01) and emptying 35.5 ± 22 vs 23.6 ± 17 cm/sec (P = 0.01), respectively. The spontaneous echo contrast increased in 4 of the 7 patients. In 4 patients of the amiodarone group, the peak flow velocities in the appendage during AF and within the first 24 hours after restoration of sinus rhythm were: filling 37.4 ± 12 vs 37.8 ± 18 cm/sec and emptying 36.4 ± 18 vs 35.9 ± 18 cm/sec, respectively (P = NS). There was no change in spontaneous echo contrast. In conclusion, patients with AF reverted to sinus rhythm using amiodarone did not show changes in left atrial mechanical function; however, patients with electrical cardioversion showed mechanical dysfunction. Further investigations on the effects of amiodarone and other drugs on the mechanical function of the atria are needed to determine if patients reverted pharmacologically require antico-agulation post reversion.     

Effect of radiofrequency ablation on atrial mechanical function in patients with atrial flutter.

Atrial stunning, as assessed by left atrial appendage emptying and increased spontaneous echo contrast, is known to occur following direct-current cardioversion of atrial fibrillation (AF) and atrial flutter (AFI). Little is known on atrial mechanical function and the time course of atrial recovery following radiofrequency ablation of AFI. Fourteen patients undergoing radiofrequency ablation of persistent typical counterclockwise AFI were enrolled. Two-dimensional and pulse Doppler transesophageal echocardiography (TEE) were performed before ablation and immediately following restoration of sinus rhythm. Left atrial spontaneous echo contrast grades, left atrial appendage emptying fractions, and peak left atrial appendage emptying velocities were measured. Transthoracic echocardiography (TTE) was performed immediately after ablation, then repeated after 1 day, 1 week, and 6 weeks to measure peak transmitral velocities and percent atrial contribution to ventricular filling. Left atrial appendage emptying velocities decreased significantly following AFI termination (44 +/- 23 cm/s before ablation vs 25 +/- 14 cm/s after ablation, p = 0.01). Left atrial appendage emptying fractions also decreased significantly (0.48 +/- 0.1 preablation vs 0.34 +/- 0.17 postablation, p = 0.02). New spontaneous echo contrast developed in 4 patients (29%) after ablation. Four patients had complete atrial standstill after ablation, and 1 patient developed a new left atrial appendage thrombus. The percent atrial contribution to ventricular filling recovered progressively over 6 weeks with significant improvement in peak transmitral velocities at day 7. Thus, atrial stunning occurs after catheter ablation of AFI and may lead to rapid formation of thrombus in the left atrial appendage. Significant improvement in left atrial function occurs in 7 days.     

Serial evaluation of left atrial dimension after cardioversion for atrial fibrillation and relation to atrial function

The size of the left atrium is usually increased during atrial fibrillation (AF). The aim of the present study was to evaluate changes in left atrial (LA) dimension after cardioversion for AF, and the relation between LA dimension and atrial function. The initial study population included 171 consecutive patients. Patients who had spontaneous cardioversion to sinus rhythm (56 patients) were compared with patients who had random cardio-version with drugs (50 patients) or direct-current (DC) shock (50 patients). Echocardiographic evaluations included LA size and volume. LA passive and active emptying volumes were calculated, and LA function was assessed. Atrial stunning was observed in 18 patients reverted with DC shock and in 7 patients reverted with drugs. The left atrium was dilated in all patients during AF (48 +/- 5 mm). The size of the left atrium decreased after restoration of sinus rhythm in all patients with spontaneous reversion to sinus rhythm, in 73% of patients reverted with drugs, and in 50% of patients reverted with DC shock. The comparison between patients with a normal mechanical atrial function and patients with reduced atrial function showed that a higher atrial ejection force was associated with a more marked reduction in LA size after restoration of sinus rhythm. A relation between LA volumes and atrial ejection force was observed in the group of patients with depressed atrial mechanical function (r = -0.78; p <0.001). The active emptying fraction was lower, although not significantly, in this group, whereas the conduit volume was increased. Thus, a depressed atrial mechanical function after cardioversion for AF was associated with a persistence of LA dilation.     

Implantable atrial defibrillator with a single-pass dual-electrode lead

OBJECTIVES

We examined the feasibility and efficacy of using a single-pass, dual-electrode (Solo) lead for atrial fibrillation (AF) detection and defibrillation.

BACKGROUND

The efficacy and safety of an implantable atrial defibrillator (IAD) has been extensively studied; however, separate right atrial (RA) and coronary sinus (CS) defibrillation leads are used for the present system.

METHODS

We studied the use of the Solo lead for AF detection and defibrillation in 17 patients who underwent cardioversion of chronic AF. The Solo lead with a proximal 6-cm RA electrode and a distal 6-cm spiral-shaped CS electrode were positioned into the CS with the RA electrode against the anterolateral RA wall. The RA-CS electrogram signal amplitudes were measured and the efficacy of the Solo lead for AF detection and defibrillation was assessed by using an external version of the IAD.

RESULTS

The leads were inserted in all patients without complication (mean fluoroscopy time: 13.3 ± 6.8 min). The mean RA-CS signal amplitude was 484 ± 229 μV during sinus rhythm and 274 ± 88 μV during AF (p < 0.05). All patients had satisfactory atrial signal amplitude to allow accurate detection of sinus rhythm. Successful cardioversion was achieved in 16/17 (94%) patients with an atrial defibrillation threshold of 320 ± 70 V (5.5 ± 2.7 J). Insufficient interelectrode spacing resulted in suboptimal electrode locations, associated with a lower atrial signal amplitude, a higher atrial defibrillation threshold and diaphragmatic stimulation.

CONCLUSIONS

These results suggest a simplified lead configuration with optimal interelectrode spacing can be used with an IAD for AF detection and defibrillation.     

Right atrial appendage thrombosis in atrial fibrillation: its frequency and its clinical predictors

This study assesses the incidence of right atrial (RA) chamber and appendage thrombosis in patients with atrial fibrillation (AF) in relation to RA appendage morphology and function. Transthoracic and multiplane transesophageal echocardiography were performed in 102 patients with AF to assess the incidence of RA and left atrial (LA) thrombi and spontaneous echo contrast. Both right and left ventricular sizes, atrial chamber and appendage sizes and function were measured. Twenty-two patients in sinus rhythm served as the control group (SR). Complete visualization of the RA appendage was feasible in 90 patients with AF. Patients with AF had lower tricuspid annular excursion (p = 0.008) and larger RA chamber area (p = 0.0001) than patients in SR. In addition, RA appendage areas were larger (p <0.05) and RA ejection fraction and peak emptying velocities (both p <0.0001) were lower in patients with AF patients than in those in SR. Equivalent differences were found for the LA appendage. Six thrombi were found in the RA appendage and 11 thrombi in the LA appendage in AF patients. Spontaneous echo contrast was found in 57% and 66% in the right atrium and in the left atrium, respectively. AF patients with RA appendage thrombi had a larger RA area (p = 0.0001), and lower RA appendage ejection fraction and emptying velocities (both p = 0.0001) than patients without thrombi. Spontaneous echo contrast was detected in all patients with thrombi. Spontaneous echo contrast was the only independent predictor of RA (p = 0.03) and LA appendage thrombosis (p = 0.036). In conclusion, multiplane transesophageal echocardiography allows the assessment of RA appendage morphology and function. RA spontaneous echo contrast is the only independent predictor of RA appendage thrombosis.     

Transesophageal echocardiography in electrical cardioversion: Is it possible to predict conversion to sinus rhythm?]

Due to its ability to safely exclude thrombi, transesophageal echocardiography (TEE) is now routinely performed in patients proposed for electrical cardioversion. However, what is the value of TEE in predicting conversion to sinus rhythm in patients with atrial fibrillation (AF)? To answer this question, TEE was performed in 21 patients with chronic AF before elective cardioversion. Patients were divided in two groups according to the outcome of cardioversion: Group A--Restoration of sinus rhythm achieved: Group B--atrial fibrillation persisted. The echocardiographic variables used to compare both groups were 1--Left Atrial size; 2--Left Atrial Appendage (LAA) systolic and diastolic dimensions; 3--LAA emptying and filling velocities; 4--LAA emptying fraction; 5--Presence of LAA spontaneous contrast. The clinical variable evaluated was 6--therapy with oral amiodarone for more than 2 weeks (> or = 200 mg/day). The results of this study showed that patients with smaller LA, adequately treated with amiodarone and with higher LAA emptying and filling velocities, have the greatest probability of conversion to sinus rhythm.     

心房颤动患者复律前后左心房功能变化的超声研究

目的　探讨心房颤动 ( AF )复律后左心房功能变化的特点。方法　选择 AF病人 96例 ,按心脏节律转复的方式分为自发性复律 ( A)组 2 4例 ,药物复律 ( B)组 40例及直流电复律 ( C)组 3 2例 ;分别应用超声心动图测定其左心房内径和容积 ,计算左心房主动和被动排空容积 ,并评价左心房功能。结果　AF时所有病人的左心房扩大 ,而恢复窦性心律后 A、B及 C组左心房内径降低者分别为 10 0 %、74%及 5 2 %。 62例左心房机械功能正常患者与 3 4例左心房功能降低患者比较有更强的左心房射血力 ( LAEF ) ,这与复律后左心房内径降低有关。左心房功能异常( L AEF<7达因 )患者左心房内径和容积分别与左心房射血力呈负相关 ( r=-0 .72和 -0 .76,P<0 .0 0 1)。左心房主动排空分数降低而管道容积却增加。结论　心房颤动复律后 ,左心房机械功能的延迟恢复与持续存在的的左心房扩大有关     

P wave dispersion and left atrial appendage function for predicting recurrence after conversion of atrial fibrillation and relation of p wave dispersion to appendage function

BACKGROUND: We investigated P wave dispersion and left atrial appendage (LAA) function for predicting atrial fibrillation (AF) relapse, and the relationship between P wave dispersion and LAA function. METHODS: Sixty-four consecutive patients with AF lasting /=5 days, LA size >/=45 mm, maximum P wave duration >/=112 ms, P wave dispersion >/=47 ms, spontaneous echo contrast, minimum LAA area >/=166 mm(2), and LAA emptying velocity <36 cm/sec were univariate predictors of recurrence (each P < 0.05). By multivariate analysis, LA size (P = 0.02), P wave dispersion (P < 0.001), and LAA emptying flow (P = 0.01) identified patients with recurrent AF. Their positive predictive values were 91, 97, and 72%, respectively. CONCLUSION: The increased P wave dispersion in addition to the dilated LA and the depressed LAA emptying flow can identify patients at risk of recurrent AF after cardioversion.     

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 < or = 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.     

Identification of good responders to rhythm control of paroxysmal and persistent atrial fibrillation by transthoracic and transesophageal echocardiography

BACKGROUND: Identification of good responders to rhythm control in the management of atrial fibrillation (AF) is worthwhile in terms of increasing hemodynamic benefit and decreasing the likelihood of unstable anticoagulation even after the Atrial Fibrillation Follow-Up Investigation of Rhythm Management. METHODS: We tested the hypothesis that atrial substrate determines the risk of recurrence on rhythm control both in patients with paroxysmal AF (PAF) and in those with persistent or sustained AF (> or =1 week, SAF). There were 90 consecutive patients (mean age 63 +/- 12 years, 67 males and 23 females) with previous PAF (n = 66) or SAF (n = 24). They were maintained in sinus rhythm successfully for at least 1 month after conversion and then studied by transthoracic and transesophageal echocardiography. All of the patients were followed regularly by determination of symptoms, 12-lead ECG and intermittent Holter recording to determine recurrence of AF after echocardiographic study. RESULTS: After 9.1 +/- 3.8 (range 3-12) months of follow-up, 23 of the 90 (26%) patients had documented recurrence of AF (67 without recurrence). Univariate analysis of demographic characteristics, medications, ECG and echocardiographic parameters revealed that, compared with the group of patients without recurrent AF, the group of those with it included more members of the SAF group (11/27 vs. 13/67, p = 0.039), included more male subjects (22/23 vs. 45/67, p = 0.045), had a larger left atrial volume index (LAVI; 27 +/- 9 vs. 22 +/- 9 ml/m2, p = 0.024) and had lower LA appendage peak emptying velocity (LAAPEV; 42 +/- 15 vs. 55 +/- 22 cm/s, p = 0.01). Multivariate Cox proportional hazards regression analysis adjusted for age, gender and AF group revealed that patients with LAVI <30 ml/m2 and LAAPEV >46 cm/s had the least recurrence of AF (relative risk 0.18, 95% confidence interval 0.06-0.55, vs. with LAVI >30 ml/m2 or LAAPEV <46 cm/s, p = 0.002). Kaplan-Meier probability of freedom from AF recurrence was significantly better when LAVI <30 ml/m2 (log-rank p = 0.02), LAAPEV > 46 cm/s (p = 0.013) or both (p = 0.004). The superiority to predict the rate of sinus rhythm maintenance was the same in the PAF and SAF groups. CONCLUSIONS: Good responders to rhythm control in the PAF and SAF groups share the characteristics of smaller LA volume and better LAA contractile function, emphasizing the critical role of atrial substrate remodeling in recurrence of AF.     

“Stunning” of the left atrium after spontaneous conversion of atrial fibrillation to sinus rhythm: Demonstration by transesophageal Doppler techniques in a canine model

Objectives. This study compared left atrial and left atrial appendage contraction velocities in sinus rhythm before and after a brief period of atrial fibrillation in a canine model.

Background. In patients, left atrial appendage contraction velocities measured during sinus rhythm after cardioversion from atrial fibrillation are depressed relative to left atrial appendage emptying velocities measured during atrial fibrillation, suggesting that the left atrial appendage is mechanically “stunned.”

Methods. This phenomenon was studied in a canine model of acute (60 min) pacing-induced atrial fibrillation followed by spontaneous reversion to sinus rhythm using epicardial and transesophageal pulsed wave Doppler. Unique features of the model include: 1) comparison of left atrial function postconversion to baseline sinus rhythm rather than to measurements during atrial fibrillation, 2) control of the duration of atrial fibrillation and 3) elimination of the extraneous influences of direct current shock and antiarrhythmic agents, which may independently depress left atrial function.

Results. Hemodynamic conditions (heart rate, mean arterial pressure, cardiac output, mean pulmonary artery pressure, mean right atrial pressure and mean left atrial pressure) at baseline, during 60 min of atrial fibrillation and after reversion to sinus rhythm were constant throughout the study period. Peak left atrial contraction velocities (measured from the transmitral flow velocity profile) were significantly (p < 0.02) reduced to 64 ± 22% of baseline values upon spontaneous conversion of atrial fibrillation to sinus rhythm and recovered to basal values by 20 min after resumption of sinus rhythm. Peak left atrial appendage contraction velocities were significantly (p < 0.001) reduced to 49 ± 24% of baseline values upon spontaneous conversion of atrial fibrillation to sinus rhythm and recovered to basal values by 40 min after reversion to sinus rhythm.

Conclusions. Even brief (60 min) periods of atrial fibrillation in normal canine hearts result in marked depression of global left atrial systolic function and regional left atrial (left atrial appendage) systolic function upon resumption of sinus rhythm. This “mechanical stunning” of left atrial systolic function appears to be more profound and of longer duration for the left atrial appendage compared with the left atrium as a whole, which may predispose the appendage to blood stasis and thrombus formation. Chronic models of atrial fibrillation need to be developed to examine the impact of longer periods of atrial fibrillation upon the magnitude and duration of postconversion left atrial “stunning.”     

Marked reduction in atrial defibrillation thresholds with repeated internal cardioversion.

OBJECTIVES: This study was performed to assess the atrial defibrillation threshold in patients with recurrent atrial fibrillation (AF) using repeated internal cardioversion. BACKGROUND: Previous studies in patients with chronic AF undergoing internal cardioversion have shown this method to be effective and safe. However, current energy requirements might preclude patients with longer-lasting AF from being eligible for an implantable atrial defibrillator. METHODS: Internal shocks were delivered via defibrillation electrodes placed in the right atrium (cathode) and the coronary sinus (anode) or the right atrium (cathode) and the left pulmonary artery. After cardioversion, patients were orally treated with sotalol (mean 189 +/- 63 mg/day). Eighty consecutive patients with chronic AF (mean duration 291 +/- 237 days) underwent internal cardioversion, and sinus rhythm was restored in 74 patients. Eighteen patients underwent repeated internal cardioversion using the same electrode position and shock configuration after recurrence of AF (mean duration 34 +/- 25 days). RESULTS: In these 18 patients, the overall mean defibrillation threshold was 6.67 +/- 3.09 J for the first cardioversion and 3.83 +/- 2.62 J for the second (p = 0.003). Mean lead impedance was 55.6 +/- 5.1 ohms and 57.1 +/- 3.7 ohms, respectively (not significant). For sedation, 6.7 +/- 2.9 mg and 3.9 +/- 2.2 mg midazolam were administered intravenously (p = 0.003), and the pain score (0 = not felt, 10 = intolerable) was 5.1 +/- 1.9 and 2.7 +/- 1.8 (p = 0.001). Uni- and multivariate analyses revealed only the duration of AF before cardioversion to be of relevance, lasting 175 +/- 113 days before the first and 34 +/- 25 days before the second cardioversion in these 18 patients (p = 0.002). CONCLUSIONS: If the duration of AF is reduced, a significant reduction in defibrillation energy requirements for internal cardioversion ensues. This might extend the group of patients eligible for an implantable atrial defibrillator despite relatively high initial defibrillation thresholds.     

Right Atrial Thrombi and Depressed Right Atrial Appendage Function After Cardioversion of Atrial Fibrillation

BACKGROUND: It has been shown that cardioversion of atrial fibrillation may result in left atrial chamber and appendage dysfunction and cause new thrombi in the left atrium. The aim of this prospective study was to investigate right atrial appendage function and assess the incidence of new right atrial thrombi after electrical cardioversion. METHODS: Transthoracic echocardiography was performed in 25 patients 4 h before and at 24 h and 7 days after electrical cardioversion to determine right and left atrial mechanical function (internal atrial defibrillation, n = 16; external electrical cardioversion, n = 9), as assessed by peak A wave velocities derived from the transtricuspid and transmitral velocity profiles. In addition, transesophageal echocardiography was performed 4 h before and 24 h after cardioversion to evaluate postcardioversion thrombus formation in the right and left atrial chambers and to assess right and left atrial appendage function. The degree of spontaneous echo contrast was noted, and peak emptying velocities of the appendages were measured before and after cardioversion. RESULTS: Peak emptying velocities of both the right atrial appendage (mean +/- SD, 0.23 +/- 0.1 vs 0.32 +/- 0.11 m/sec; P = 0.02) and the left atrial appendage (0.3 +/- 0.15 vs 0.4 +/- 0.15 m/sec; P = 0.01) were significantly lower 24 h after cardioversion compared with 4 h before cardioversion, respectively. The degree of spontaneous echo contrast increased in the left atrium after cardioversion from 1.0 +/- 1.2 to 1.9 +/- 2.1 (P = 0.02), and in the right atrium, it increased from 0.8 +/- 1.1 to 1.2 +/- 1.1 (P = 0.1) after cardioversion. Peak A wave transtricuspid velocity increased from 0.26 +/- 0.05 m/sec at 24 h to 0.38 +/- 0.06 m/sec (P = 0.001) after 7 days; respective values for transmitral peak A wave velocity were 0.39 +/- 0.15 and 0.54 +/- 0.16 m/sec (P = 0.009). No thrombi were found in either the right or left atrium before cardioversion. In two patients, new thrombi in the right atrium were detected 24 h after internal atrial defibrillation. Thrombi were located at the superior rim of the fossa ovalis in both patients with patent foramen ovale. Another patient had developed a thrombus in the left atrial appendage. CONCLUSIONS: Electrical cardioversion may not only cause left atrial chamber and appendage dysfunction and left atrial thrombi but also lead to depressed right atrial appendage function and the generation of new thrombi in the body of the right atrium.     

Left atrial mechanical function after brief duration atrial fibrillation

ObjectivesThis study examined the effect of brief duration atrial fibrillation on left atrial and left atrial appendage mechanical function in humans with structural heart disease.BackgroundLeft atrial dysfunction and the development of spontaneous echo contrast (SEC) may follow the cardioversion of atrial fibrillation (AF) to sinus rhythm. This phenomenon has been termed “stunning” and is implicated in the development of atrial thrombus and embolic stroke. The effects of brief duration AF on left atrial mechanical function in humans are unknown.MethodsTwenty-four patients (23 men, aged 59.1 ± 12.7 years) with significant structural heart disease (ejection fraction 31.2 ± 9.0%, left atrial diameter 4.9 ± 0.4 cm) undergoing implantation of a ventricular cardiodefibrillator underwent transesophageal echocardiography to evaluate left atrial appendage emptying velocities (LAAeV) and SEC before, during and after a 15-min period of AF induced by rapid right atrial pacing. Atrial fibrillation was then permitted to terminate spontaneously within 5 min or was reverted with an endocardial direct current shock. Velocities and SEC were assessed in sinus rhythm pre-AF, during AF and immediately, 5 and 10 min after reversion to sinus rhythm.ResultsAtrial fibrillation terminated spontaneously in 10 patients after 16.1 ± 1.0 min. Endocardial direct current (DC) cardioversion of 10.4 ± 6.4 J was required in 14 patients after AF lasting 20 min. Mean LAAeV pre-AF (50.0 ± 17.5 cm/s) was not significantly different to LAAeV immediately (52.8 ± 16.7 cm/s), 5 min (54.3 ± 16.4 cm/s) or 10 min (53.7 ± 15.7 cm/s) after reversion to sinus rhythm. Atrial stunning defined as a reduction in LAAeV of >20% was not observed in any patient. Fourteen of 24 patients (58%) developed SEC during AF, which resolved within 30 s of AF termination. There were no significant differences between LAAeV in those patients reverting with DC shock (pre-AF 50.6 ± 16.2 cm/s vs. immediately post-AF 54.7 ± 16.6 cm/s) or in those patients with spontaneous reversion (pre-AF 48.9 ± 20.2 cm/s vs. immediately post-AF 49.8 ± 17.3 cm/s).ConclusionsSignificant left atrial stunning was not observed after brief duration AF in humans with structural heart disease. Transient left atrial SEC develops in a significant proportion of these patients during AF but resolves rapidly on reversion to sinus rhythm. These findings suggest that the risk of thromboembolism may be low after brief duration AF that terminates either spontaneously or with an endocardial DC shock even in patients with significant structural heart disease. These findings have important implications for recipients of implantable devices that are capable of atrial defibrillation in response to AF.     

非瓣膜病心房颤动病人电复律前后左心房功能变化研究

目的评价经食道超声心动图(TEE)对非瓣膜病心房颤动(房颤)病人电复律前后左心房功能变化.方法选择房颤持续2周以上的非瓣膜疾病病人18例,其中原发性高血压6例,扩张型心肌病6例,脑血栓4例,缺血性心肌病2例.应用TEE确定左心房内无血栓后行电复律,转为窦性心律者测定左心耳血流最大速度及流速积分,肺静脉血流最大速度及流速积分、二尖瓣血流最大速度、流速积分及减速时间.结果左心耳排空速度于复律后显著减少,有显著性差异(P＜0.05),排空指数增加(P＞0.05),电复律后肺静脉收缩期、舒张期最大流速及其流速积分比值无显著差异(P＞0.05),收缩期最大流速积分在左、右肺静脉均有显著差异(P均＜0.05).复律前后舒张期最大流速积分在右肺静脉有显著性差异(P＜0.05),左肺静脉差异不显著(P＞0.05).二尖瓣血流E波最大速度及E波与A波比值(E/A)增加.结论适合的抗凝治疗及TEE确认心房内无附壁血栓后进行电复律治疗,安全又无并发症.TEE能评价房颤病人电复律后的左心房功能变化.电复律后心房的电活动及机械活动均微弱,能引起左心房功能不全及栓塞,所以心房功能完全恢复前均有必要进行抗凝治疗.     

Relation of early termination of persistent atrial fibrillation by cardioversion or drugs to ablation outcomes

Current ablation consensus documents define persistent atrial fibrillation (AF) as AF lasting >1 week to 1 year or AF requiring cardioversion or pharmacologic conversion in <1 week. These 2 persistent AF subgroups may have different clinical characteristics and ablation outcomes. We compared 179 patients whose persistent AF was always terminated in <1 week by cardioversion/drugs to 244 whose AF actually lasted >1 week to 1 year. Patients with AF termination in <1 week by cardioversion/drugs had smaller left atrial (LA) size (4.1 ± 0.6 vs 4.5 ± 0.7 cm, p <0.0001), a longer AF history (7.5 ± 7.5 vs 6.0 ± 7.2 years, p = 0.035), more failed drugs (1.6 ± 1.0 vs 1.3 ± 1.0, p = 0.004), lower body mass index (28.5 ± 5.5 vs 30.3 ± 5.5, p = 0.0008), and fewer cardiomyopathies (3.9% vs 11.1%, p = 0.01). Cox multivariate analysis showed that LA size (p = 0.02), female gender (p = 0.001), and coronary artery disease (p = 0.03) predict ablation failure. There was a linear relation between duration of longest AF episode and LA size (p = 0.0001). Longest AF episode duration was the only factor predicting LA size (p = 0.001). Kaplan-Meier analysis showed more patients with AF termination in <1 week by cardioversion/drugs were free of AF after ablation (p = 0.042) than those whose AF actually lasted >1 week to 1 year. Once AF lasted >1 week, duration up to 1 year did not affect ablation success. In conclusion, patients whose persistent AF is always terminated by drugs/cardioversion in <1 week have different clinical characteristics and better ablation outcomes than patients whose AF persists beyond 1 week. This suggests that maintaining sinus rhythm before ablation is beneficial and that the definition of AF2 may need revision.     

The left atrial function index: a rhythm independent marker of atrial function.

AIMS: This study evaluates a simple echocardiographic rhythm independent expression of left atrial (LA) function, 'the left atrial function index' (LAFI). BACKGROUND: Quantitation of LA function is challenging and often established parameters including peak A are limited to sinus rhythm (SR). We hypothesized that atrial function could be characterized independent of rhythm by combining analogues of LA volume, reservoir function and LV stroke volume. METHODS: Seventy-two patients with chronic atrial fibrillation (CAF) were followed for six months post cardioversion (CV). Thirty-seven age matched healthy subjects were controls. The LAFI = LAEF x LVOT-VTI/LAESVI (LAEF = LA emptying fraction, LAESVI = maximal LA volume indexed to BSA, LVOT-VTI = outflow tract velocity time integral). RESULTS: The LAFI pre-CV in the CAF group was depressed vs controls (0.10 +/- 0.05 vs 0.54 +/- 0.17; P = 0.0001). Post-CV, LAFI was lower in persistent AF than in those restored to SR (AF vs SR: 0.08 +/- 0.03 vs 0.15 +/- 0.08; P = 0.0001), improved progressively in SR and was unchanged when AF persisted. CONCLUSION: The LAFI, a simple, rhythm independent expression of atrial function, appears sensitive to differences between individuals in AF and those restored to SR and justifies clinical and investigative applications.     

Long-term outcome of patients with drug-refractory atrial flutter and fibrillation after single- and dual-site right atrial pacing for arrhythmia prevention

Objectives. An initial crossover study comparing dual- and single-site right atrial pacing was performed followed by a long-term efficacy and safety evaluation of dual-site right atrial pacing in patients with drug-refractory atrial fibrillation (AF). Also examined was the efficacy of two single-site right atrial pacing modes (high right atrium and coronary sinus ostium) and the long-term need for cardioversion, antithrombotic and antiarrhythmic drug therapies during dual-site atrial pacing.

Methods. Thirty consecutive patients with drug-refractory symptomatic AF and documented primary or drug-induced bradycardia were implanted with a dual chamber rate-responsive pacemaker and two atrial leads. Single-site atrial pacing was performed at the high right atrium or the coronary sinus ostium. Continuous atrial pacing was maintained.

Results. Mean arrhythmia-free intervals increased from 9 ± 10 days in the control period preceding implant to 143 ± 110 days (p < 0.0001) in single-site right atrial pacing and 195 ± 96 days in dual-site right atrial pacing (p < 0.005 versus single-site pacing and p < 0.0001 versus control). Dual-site right atrial pacing significantly increased the proportion of patients free of AF recurrence (89%) as compared to single-site right atrial pacing (62%, p = 0.02). High right atrial pacing and coronary sinus ostial pacing had similar efficacy for AF prevention. Effective rhythm control was achieved in 86% of patients during dual right atrial pacing. Seventy-eight percent of patients at 1 year and 56% at 3 years remained free of symptomatic AF. The need for cardioversion was reduced after pacemaker implant (p < 0.05) and antithrombotic therapy was reduced (p < 0.06) without any thromboembolic event. Coronary sinus ostial lead dislodgement was not observed after discharge.

Conclusions. Atrial pacing in combination with antiarrhythmic drugs eliminates or markedly reduces recurrent AF. Prevention of AF is enhanced by dual-site right atrial pacing. High right atrial and coronary sinus ostial pacing do not differ in efficacy. Dual-site right atrial pacing is safe, achieves long-term rhythm control in most patients, decreases the need for cardioversion, and antithrombotic therapy can be selectively reduced.