Mechanical dysfunction of the left atrium and the left atrial appendage following cardioversion of atrial fibrillation and its relation to total electrical energy used for cardioversion

In 39 patients undergoing electrical cardioversion for atrial fibrillation (AF), we examined the effect of total electrical energy used for cardioversion on postcardioversion peak left atrial (LA) rapid filling velocity (A) and the atrial emptying fraction, and recovery of LA effective mechanical atrial function (defined as peak A velocity > or = 0.50 m/s), as assessed by transthoracic echocardiography. In a subset of 27 patients who underwent pre- and postcardioversion transesophageal echocardiography, we assessed the relation between total electrical energy and LA appendage filling and emptying velocities and spontaneous echo contrast. Patients were randomized to receive an initial shock of 1.5 J/kg based on body weight, or 2.5, 3.5, 5 J/kg, or 360 J, followed sequentially by higher shock intensities until sinus rhythm was achieved. Patients were classified into 4 groups based on quartiles of total energy delivered for cardioversion. Conversion to sinus rhythm was associated with a significant decrease in the LA appendage filling velocities (0.42 +/- 0.20 m/s vs 0.29 +/- 0.14 m/s; p = 0.002) and LA appendage emptying velocities (0.40 +/- 0.22 m/s vs 0.29 +/- 0.18 m/s; p = 0.03), but no change in the incidence of spontaneous echo contrast (61% vs 70%, p = 0.08). The 4 groups of patients did not differ with respect to postcardioversion LA appendage filling velocities, LA appendage emptying velocities, incidence of spontaneous echo contrast, or worsening of spontaneous echo contrast. Similarly, the change in LA appendage filling and emptying velocities associated with cardioversion was not different between the groups. Furthermore, postcardioversion peak A velocity and atrial emptying fraction and recovery of effective mechanical atrial function were similar between the 4 groups. These results suggest that in patients undergoing electrical cardioversion for AF, the total electrical energy used for cardioversion has no effect on the mechanical function of the left atrium or LA appendage following cardioversion.     

Echocardiographic factors predicting the maintenance of sinus rhythm one year after cardioversion for non-valvular atrial arrhythmias]

Echocardiographic factors predictive of the maintenance of sinus rhythm after successful cardioversion were investigated in 94 patients with non-valvular atrial arrhythmias of recent onset. Seventy-five patients with atrial fibrillation and 19 with atrial flutter admitted for reduction of their arrhythmias underwent transthoracic and transoesophageal echocardiography. After excluding a thrombus in the left atrial appendage or checking that it had disappeared (5 patients), and electrical (n = 74) or pharmacological (n = 20) cardioversion was successfully performed. The maintenance of sinus rhythm (n = 44) or recurrence of arrhythmia (n = 50) were controlled every 3 months for one year. The mean value of the peak positive blood flow in the left atrial appendage was 38 +/- 20 cm/s for the whole group. It was not possible to identify an echocardiographic parameter predictive of maintenance of sinus rhythm at one year either in the whole group or in the subgroups with atrial flutter or atrial fibrillation. In the group in atrial flutter, the mean value of the peak positive blood flow in the left atrial appendage was significantly greater than in the group with atrial fibrillation: 49 +/- 22 cm/s vs 35 +/- 18 cm/s, respectively; p < 0.05. The peak of positive flow in the left atrial appendage was statistically related to indirect parameters of left atrial function and of left ventricular function in the group with atrial fibrillation but only with parameters of left ventricular function in the smaller group with atrial flutter.     

Monitoring of lineage-specific chimaerism allows early prediction of response following donor lymphocyte infusions for relapsed chronic myeloid leukaemia

Thrombogenesis in the left atrial appendage (LAA) has been related to the special morphology of this cavity and to its size and degree of dysfunction. However, no study has focused on LAA function in conjunction with left atrial (LA) function in both sinus rhythm (SR) and nonrheumatic idiopathic atrial fibrillation (AF) in relation to clinical status (cardioembolic stroke). Forty-three patients in SR (14 patients with stroke, 29 control subjects) and 45 patients in AF (27 patients with stroke, 18 control subjects) were examined by transthoracic and transesophageal echocardiography. Baseline clinical characteristics and standard transthoracic and transesophageal measurements of the LA and LAA (size, fractional area change, flow measurements, spontaneous echo contrast, and thrombus) were recorded and compared in relation to cardiac rhythm. Patients in the stroke-SR group showed a significant decrease of fractional area change in the LA (32%+/-15%) and LAA (34%+/-15%) in relation to control subjects (43%+/-10%, p = 0.035, 49%+/-13%, p = 0.006, respectively). Patients in the stroke-AF group showed significant reduction of appendage flow measurements (outward velocity = 22+/-13 vs 33+/-19 cm/sec, p = 0.036), whereas no differences were detected in the center of the LA. In multiple regression analysis, the presence of cardioembolic stroke was positively associated with the presence of spontaneous echo contrast (p = 0.0253) and spontaneous echo contrast negatively associated with appendage inward flow velocity (p<0.001). Cardioembolic stroke in patients in SR is associated with a global decrease of shortening in both cavities and in patients with AF, with a reduction of LAA flow parameters. Patients with spontaneous echo contrast, thrombus, or both showed further reduction of shortening and flow velocities in both cavities, indicating a more advanced stage of dysfunction.     

Exclusion of atrial thrombus by transesophageal echocardiography does not preclude embolism after cardioversion of atrial fibrillation. A multicenter study

BACKGROUND: Transesophageal echocardiography (TEE) has been used recently to detect atrial thrombi before cardioversion of atrial arrhythmias. It has been assumed that embolic events after cardioversion result from embolism of preexisting atrial thrombi that are accurately detected by TEE. This study examined the clinical and echocardiographic findings in patients with embolism after cardioversion of atrial fibrillation despite exclusion of atrial thrombi by TEE. METHODS AND RESULTS: Clinical and echocardiographic data in 17 patients with embolic events after TEE-guided electrical (n = 16) or pharmacological (n = 1) cardioversion were analyzed. All 17 patients had nonvalvular atrial fibrillation, including four patients with lone atrial fibrillation. TEE before cardioversion showed left atrial spontaneous echo contrast in five patients and did not show atrial thrombus in any patient. Cardioversion resulted in return to sinus rhythm without immediate complication in all patients. Thirteen patients had cerebral embolic events and four patients had peripheral embolism occurring 2 hours to 7 days after cardioversion. None of the patients were therapeutically anticoagulated at the time of embolism. New or increased left atrial spontaneous echo contrast was detected in four of the five patients undergoing repeat TEE after cardioversion including one patient with a new left atrial appendage thrombus. CONCLUSIONS: Embolism may occur after cardioversion of atrial fibrillation in inadequately anticoagulated patients despite apparent exclusion of preexisting atrial thrombus by TEE. These findings suggest de novo atrial thrombosis after cardioversion or imperfect sensitivity of TEE for atrial thrombi and suggest that screening by TEE does not obviate the requirement for anticoagulant therapy at the time of and after cardioversion. A randomized clinical trial is needed to compare conventional anticoagulant management with a TEE-guided strategy including anticoagulation after cardioversion.     

Alteration of peripheral vasodilatory reserve capacity after cardioversion of atrial fibrillation

In atrial fibrillation, exercise capacity is often reduced. This is usually ascribed to a decreased cardiac output as compared with sinus rhythm. Very few studies, however, have focused on changes in the peripheral blood flow during atrial fibrillation as a potential mechanism for exercise limitation. The aim of the present study was to determine the effect of conversion of atrial fibrillation to sinus rhythm on peripheral blood flow. Calf blood flow, using an electrocardiogram-triggered venous occlusion plethysmograph, and peak oxygen consumption (peak VO2), using treadmill exercise testing, were studied in 28 patients with chronic atrial fibrillation eligible for electrical cardioversion. Measurements were performed before cardioversion, and repeated 1 day and 1 month thereafter. Calf blood flow at rest, maximal calf blood flow, and minimal calf vascular resistance during the hyperaemic response immediately following 700 J of calf exercise were determined plethysmographically. One day and 1 month after cardioversion, 23 and 14 patients were still in sinus rhythm, respectively. In patients who still had sinus rhythm after 1 month, maximal calf blood flow increased from 33.7 +/- 12 to 40.0 +/- 13 ml. 100 ml-1.min-1 (P < 0.01) and minimal calf vascular resistance fell from 3.2 +/- 0.9 to 2.7 +/- 0.7 mmHg. ml-1. 100 ml-1. min-1 (P < 0.01); peak VO2 increased from 21.3 +/- 4 to 24.2 +/- 5 ml. min-1. kg-1 (P < 0.001). Calf blood flow at rest did not improve. In contrast, no significant changes in maximal calf blood flow, minimal calf vascular resistance and peak VO2 occurred in patients who had atrial fibrillation 1 month after cardioversion. A significant correlation was found between changes in maximal calf blood flow and peak VO2 1 month after cardioversion (r = 0.53, P < 0.01). One day after cardioversion, no changes in calf blood flow or peak VO2 were found, either in patients with sinus rhythm or atrial fibrillation. In conclusion, transition from chronic atrial fibrillation to sinus rhythm is associated with a (delayed) improvement in maximal calf blood flow, minimal calf vascular resistance, and peak VO2. Our findings suggest that increase in vasodilatory reserve capacity may contribute to the improvement of exercise capacity after cardioversion of atrial fibrillation.     

Perindopril postmarketing surveillance: a 12 month study in 47,351 hypertensive patients

We investigated the effect of electrical cardioversion of atrial fibrillation in patients with heart failure. The study group consisted of 24 patients with mild to moderate heart failure [13 men, mean age 67+/-7 years, mean peak oxygen consumption (peak VO2) 16.3+/-2.8 ml/min/kg] and chronic atrial fibrillation (median duration 19 (1-228) months). Patients were stable on digoxin, diuretics, nitrates and angiotensin converting enzyme inhibitors; no prophylaxis with antiarrhythmics was started after cardioversion. Cardioversion was unsuccessful in 6 patients; of the 18 patients in whom sinus rhythm was obtained 9 had a relapse of atrial fibrillation within 6 weeks after cardioversion. The remaining 9 patients with maintenance of sinus rhythm and the 15 (6+9) patients with atrial fibrillation at follow-up after 6 weeks did not differ with respect to any baseline characteristic, including age, peak VO2, duration of atrial fibrillation, echocardiographic left ventricular and left atrial dimensions, plasma atrial natriuretic peptide and norepinephrine. In the patients with maintenance of sinus rhythm, baseline measurements were repeated at follow-up. Peak VO2 did not change significantly (16.7+/-2.8 to 17.6+/-3.3 ml/min/kg, P=0.29); also, echo parameters, atrial natriuretic peptide and norepinephrine were not significantly affected. These results indicate that it is difficult to achieve lasting sinus rhythm through electrical cardioversion in patients with atrial fibrillation and mild to moderate heart failure. Moreover, in patients with maintenance of sinus rhythm after cardioversion no significant benefit in terms of peak VO2, cardiac dimensions, and neurohumoral status is to be expected. Hence, indiscriminate cardioversion of atrial fibrillation in the setting of heart failure does not appear to be useful.     

Value of transesophageal echocardiography in the therapeutic management of non-valvular atrial fibrillation

Transoesophageal echocardiography (TOE) has transformed the management of atrial fibrillation. It has become the reference method for assessing thromboembolic risk and therefore the indication for anticoagulant therapy in non-valvular atrial fibrillation. The predictive factors of embolism are the presence of intraatrial spontaneous contrast echo or thrombosis, dilatation of the left atrial appendage (> 6 cm2) and reduced outflow velocities of the left atrial appendage (< 0.25 m/sec). The value of TOE before electrical cardioversion is under assessment. The predictive value of TOE in the success of cardioversion and maintenance of sinus rhythm at one year is subject of controversy. The projective ACUTE study (Assessment of Cardioversion Using Transoesophageal Echocardiography) should determine whether cardioversion guided by the results of TOE reduces the embolic risk and shortens the duration of anticoagulation before cardioversion.     

The grammatical properties of mass nouns: an aphasia case study

A total of 168 consecutive patients with predominant rheumatic mitral stenosis were evaluated by transthoracic (TTE) and transesophageal echocardiography (TEE). Of the 168 patients, 35 had previous embolic events (group I) and 133 had no emboli (group II). A total of 77 (45.8%) patients had atrial fibrillation. The frequency of atrial fibrillation was higher in group I than group II (68.6% vs 39.8%, p < 0.001). The incidence of left atrial enlargement was greater in group I (p < 0.001). Mitral valve area was found to be smaller in group I compared to group II (p < 0.001). In group I 83.3% and 29.2% of the patients with atrial fibrillation had left atrial spontaneous echo contrast (SEC) and left atrial thrombus, respectively, and 72.7% of the patients with sinus rhythm had left atrial SEC. In group II 79.2% and 20.8% of the patients with atrial fibrillation had left atrial SEC and left atrial thrombus whereas 28.6% and 2.6% of the patients with sinus rhythm had left atrial SEC and left atrial thrombus, respectively. The incidence of left atrial thrombus was significantly different in those patients with compared to those without embolic events (20% vs 9.7%, p < 0.01). In groups I and II, 28 of 35 (80%) and 64 of 133 (48.1%) patients had left atrial SEC (p < 0.01). Patients with left atrial SEC had a greater left atrial size (p < 0.01) and smaller mitral valve area (p < 0.01). Left atrial size was normal in 2 patients with left atrial SEC and SEC was not found in 55 patients with enlarged left atrium. Multiple logistic regression analysis showed that atrial fibrillation, mitral valve area and left atrial enlargement were independent predictors of the SEC (p < 0.001) and left atrial SEC was the principal determinant of thromboembolism. These data suggest that regardless of rhythm and atrial size, left atrial SEC is a principal determinant of thromboembolic risk in mitral stenosis. TEE may be able to detect those patients with mitral stenosis at risk for emboli and guide appropriate therapy.     

Electrophysiological properties in patients undergoing atrial compartment operation for chronic atrial fibrillation with mitral valve disease

AIMS: Surgical treatment for atrial fibrillation is now feasible in selective cases. The aim of this study was to assess the electrophysiological properties of patients undergoing atrial compartment operation for chronic atrial fibrillation. METHODS AND RESULTS: Electrophysiological studies were performed in 20 mitral valve patients with atrial fibrillation who had been maintained in sinus rhythm for more than 1 year after atrial compartment operation. Intra-cardiac recording and programmed electrical stimulation were performed in various atrial compartments. The parameters studied included sinus node function, atrial conduction and refractoriness, atrioventricular conduction function and inducible arrhythmias if any. Intra-cardiac recordings showed that the rhythm was of sinus origin in all cases, with the earliest atrial activity located in the high right atrium. The mean sinus cycle length was 750 +/- 110 ms, AH time 106 +/- 29 ms, and HV time 53 +/- 7 ms. The sinus node function was normal in 18 patients (90%), and only two patients had prolonged sinus node recovery and sino-atrial conduction. The right atrial appendage compartment was driven by the sinus node in all patients. However, the conduction time from the high right atrium to the right atrial appendage compartment was markedly prolonged in 12 of 15 patients (80%) undergoing the three-compartment operation in which an incision was placed between the high right atrium and right atrial appendage compartments. On the other hand, the electrical activities in the left atrial compartment were much more varied. In 13 of 20 patients (65%), the left atrial compartment was driven by the sinus node; 11 of the 13 patients had a normal or mildly prolonged conduction time (ranged 75 to 146 ms), whereas two patients had a marked delay in conduction (200 ms and 266 ms, respectively). In the remaining seven patients, the left atrial compartments were dissociated from the rest of the heart; five of them had a quiescent left atrium, one a fluttering left atrial rhythm, and one a slow left atrial rhythm. The effective refractory period was longer in the left atrial compartment (242 +/- 47 ms) as compared to that of the high right atrium (224 +/- 26 ms, P < 0.01) and right atrial appendage compartments (219 +/- 25 ms, P < 0.01). Programmed electrical stimulation could not induce atrial fibrillation in any patient, whereas two patients had inducible atrial flutter and three repetitive atrial responses. CONCLUSIONS: (1) Atrial compartment operation does not impair sinus node function in most cases. (2) Elimination of atrial fibrillation while maintaining the electrical connection between different atrial compartments is feasible.     

Cardioversion in atrial fibrillation. Results and complications in 1,152 prospective patients. Study Group of the Working Society of Leading Cardiologic Hospital Physicians

BACKGROUND: Pharmacological and direct-current cardioversion of atrial fibrillation are often performed interventions. Little is known about results and complications of cardioversion in daily practise. PATIENTS AND METHODS: Demographic, procedural and outcome data from patients with cardioversion of atrial fibrillation were collected in a prospective, multicenter registry of 61 hospitals. RESULTS: Between July 1994 and December 1994 1152 patients with a mean age of 64 +/- 11 years were registered on an intention-to-treat basis. 62% were male. The most prevalent underlying disorders were coronary artery disease (34.7%), valvular heart disease (18.1%), and cardiomyopathy (6.9%). 16.4% of patients had lone atrial fibrillation. New onset atrial fibrillation was reported in 21%, paroxysmal in 32% and chronic in 47% of patients. The mean duration of atrial fibrillation was 7 +/- 26 weeks (range 1 day to 7 years, median 5 days). In 3.8% of patients no cardioversion attempt was made and follow-up was not possible in another 5.5%. 19.2% of patients cardioverted spontaneously. Direct current cardioversion was attempted in 39.7% and pharmacological cardioversion in 31.8% of patients. Cardioversion was successful (sinus rhythm at discharge) in 96.4% of spontaneous cardioversion, in 73.1% of direct current cardioversion and in 84.4% of pharmacological cardioversion. Success of cardioversion was significantly related to duration of atrial fibrillation, NYHA functional class and left atrial diameter (p < 0.001). In 55 (4.8%) cases complications were reported of which 14 were fatal. Five cases of sudden death occurred, all of which were related to quinidine therapy for pharmacological cardioversion. Five cases of embolism were reported. Two were not associated with cardioversion attempts and 3 occurred within 24 hours after successful direct current cardioversion. Two of these patients were effectively anticoagulated at the time of cardioversion. A total of only 62% of patients with atrial fibrillation of more than 48 hours duration were anticoagulated for cardioversion with coumadine or i.v. heparin. CONCLUSIONS: The main risks of cardioversion are fatal proarrhythmic events in pharmacological attempts to restore sinus rhythm. The risk of embolism is despite low rates of effective anticoagulation low.     

Severely reduced left atrial appendage function: a cause of embolic stroke in patients in sinus rhythm?

Recently, attention has been focused on transesophageal echocardiographic detection of left atrial appendage function to assess of risk of thrombus formation because of potential benefit of anticoagulation therapy. However, most of these studies have been conducted in patients with atrial fibrillation or mitral valve disease. In this article we review cases of 2 patients without valvular disease who had embolic stroke in sinus rhythm. Transesophageal echocardiography revealed thrombi in the left atrial appendage in both patients. The left atrial appendage function in these patients was compared with that in patients with chronic atrial fibrillation and a control group in sinus rhythm. Left atrial appendage function in the patients with stroke and sinus rhythm was significantly lower than that of patients in the control group in sinus rhythm (P < .001) and was similar to the appendage function in patients with chronic atrial fibrillation. These observations provide further evidence that the finding of reduced left atrial appendage function can be a cause of stroke in patients with sinus rhythm even in the absence of mitral valve disease. Reduced left atrial appendage function may identify patients with unexplained stroke who should receive anticoagulation therapy even in the absence of detectable appendage thrombi.     

Effect of flecainide on atrial and ventricular refractoriness and conduction in patients with normal left ventricle. Implications for possible antiarrhythmic and proarrhythmic mechanisms

We studied the effects of intravenous flecainide (2 mg.kg-1) on atrial and ventricular refractoriness and conduction during sinus rhythm, induced atrial fibrillation and atrial pacing at rates of 100, 120 and 150 ppm, in 14 patients with normal left ventricle. Flecainide caused a significant increase in QRS duration during sinus rhythm (mean +/- SD: 87.2 +/- 8.4 ms vs 102.8 +/- 9.1 ms, P < 0.001), atrial fibrillation (87.8 +/- 10.0 ms vs 108.8 +/- 13.7 ms, P < 0.001) and at all paced rates. The duration of the atrial electrogram was significantly increased during sinus rhythm (54.9 +/- 13.2 ms vs 64.8 +/- 16.6 ms, P = 0.003) and at all pacing rates. The PA interval was also significantly prolonged, as was the pacing stimulus-to-atrial-electrogram interval at all pacing rates. There was increased QRS duration and atrial electrogram prolongation at higher pacing rates. Atrial refractoriness was prolonged during sinus rhythm (216.4 +/- 28.2 vs 228.6 +/- 36.1, P = 0.02), but not during atrial pacing at any rate. The QT interval, but not the JT interval or ventricular refractoriness, was significantly prolonged during sinus rhythm and at all pacing rates. Flecainide slows atrial conduction in a use dependent manner and increases atrial refractoriness during sinus rhythm but not during faster atrial pacing, thus not displaying a use-dependent effect. QRS duration is prolonged in a use-dependent manner without a commensurate increase in ventricular refractoriness. In the presence of rapidly conducted atrial fibrillation, which was not found to be slowed by flecainide, this effect may constitute a proarrhythmic mechanism even in patients with no apparent myocardial abnormality.     

Favorable effects of flecainide in transvenous internal cardioversion of atrial fibrillation

OBJECTIVES: The aim of the study was to evaluate the effects of intravenous (IV) flecainide on defibrillation energy requirements in patients treated with low-energy internal atrial cardioversion. BACKGROUND: Internal cardioversion of atrial fibrillation is becoming a more widely accepted therapy for acute episode termination and for implantable atrial defibrillators. METHODS: Twenty-four patients with atrial fibrillation (19 persistent, 5 paroxysmal) underwent elective transvenous cardioversion according to a step-up protocol. After successful conversion in a drug-free state, atrial fibrillation was induced by atrial pacing; IV flecainide (2 mg/kg) was administered and a second threshold was determined. In patients in whom cardioversion in a drug-free state failed notwithstanding a 400- to 550-V shock, a threshold determination was attempted after flecainide. RESULTS: Chronic persistent atrial fibrillation was converted in 13/19 (68%) patients at baseline and in 16/19 (84%) patients after flecainide. Paroxysmal atrial fibrillation was successfully cardioverted in all the patients. A favorable effect of flecainide was observed either in chronic persistent atrial fibrillation (13 patients) or in paroxysmal atrial fibrillation (5 patients) with significant reductions in energy requirements for effective defibrillation (persistent atrial fibrillation: 4.42+/-1.37 to 3.50+/-1.51 J, p < 0.005; paroxysmal atrial fibrillation: 1.68+/-0.29 to 0.84+/-0.26 J, p < 0.01). In 14 patients not requiring sedation, the favorable effects of flecainide on defibrillation threshold resulted in a significant reduction in the scores of shock-induced discomfort (3.71+/-0.83 vs. 4.29+/-0.61, p < 0.005). No ventricular proarrhythmia was observed for any shock. CONCLUSIONS: Intravenous flecainide reduces atrial defibrillation threshold in patients treated with low-energy internal atrial cardioversion. This reduction in threshold results in lower shock-induced discomfort. Additionally, flecainide may increase the procedure success rate in patients with chronic persistent atrial fibrillation.     

Clinical shock tolerability and effect of different right atrial electrode locations on efficacy of low energy human transvenous atrial defibrillation using an implantable lead system

OBJECTIVES: The objectives of this study were 1) to evaluate the effect of different right atrial electrode locations on the efficacy of low energy transvenous defibrillation with an implantable lead system; and 2) to qualitate and quantify the discomfort from atrial defibrillation shocks delivered by a clinically relevant method. BACKGROUND: Biatrial shocks result in the lowest thresholds for transvenous atrial defibrillation, but the optimal right atrial and coronary sinus electrode locations for defibrillation efficacy in humans have not been defined. METHODS: Twenty-eight patients (17 men, 11 women) with chronic atrial fibrillation (AF) (lasting > or = 1 month) were studied. Transvenous atrial defibrillation was performed by delivering R wave-synchronized biphasic shocks with incremental shock levels (from 180 to 400 V in steps of 40 V). Different electrode location combinations were used and tested randomly: the anterolateral, inferomedial right atrium or high right atrial appendage to the distal coronary sinus. Defibrillation thresholds were defined in duplicate by using the step-up protocol. Pain perception of shock delivery was assessed by using a purpose-designed questionnaire; sedation was given when the shock level was unacceptable (tolerability threshold). RESULTS: Sinus rhythm was restored in 26 of 28 patients by using at least one of the right atrial electrode locations tested. The conversion rate with the anterolateral right atrial location (21 [81%] of 26) was higher than that with the inferomedial right atrial location (8 [50%] of 16, p < 0.05) but similar to that with the high right atrial appendage location (16 [89%] of 18, p > 0.05). The mean defibrillation thresholds for the high right atrial appendage, anterolateral right atrium and inferomedial right atrium were all significantly different with respect to energy (3.9 +/- 1.8 J vs. 4.6 +/- 1.8 J vs. 6.0 +/- 1.7 J, respectively, p < 0.05) and voltage (317 +/- 77 V vs. 348 +/- 70 V vs. 396 +/- 66 V, respectively, p < 0.05). Patients tolerated a mean of 3.4 +/- 2 shocks with a tolerability threshold of 255 +/- 60 V, 2.5 +/- 1.3 J. CONCLUSIONS: Low energy transvenous defibrillation with an implantable defibrillation lead system is an effective treatment for AF. Most patients can tolerate two to three shocks, and, when the starting shock level (180 V) is close to the defibrillation threshold, they can tolerate on average a shock level of 260 V without sedation. Electrodes should be positioned in the distal coronary sinus and in the high right atrial appendage to achieve the lowest defibrillation threshold, although other locations may be suitable for certain patients.     

Clinical and echocardiographic features influencing recovery of atrial function after cardioversion of atrial fibrillation

Atrial mechanical dysfunction after cardioversion for atrial fibrillation has been widely evaluated in recent years. Nevertheless, the influence of many clinical and echocardiographic parameters is not yet understood. The aim of the present study was to evaluate the influence of clinical and echocardiographic parameters on the return of effective atrial contraction. A total of 109 patients were evaluated: 41 patients had spontaneous recovery of sinus rhythm and 68 patients were randomly treated using either direct-current (DC) shock or intravenous procainamide. Elective cardioversion was accomplished pharmacologically in 23 patients (67%) and with DC shock in 29 patients (85%). Patients underwent a complete echocardiographic examination 1 hour after the restoration of sinus rhythm and after 1 and 7 days and 1 month. The following parameters were evaluated: patient age, cardiac disease, duration and etiology of atrial fibrillation, mode of cardioversion, left ventricular diameters and function, and left atrial diameter and function assessed as atrial ejection force. The relation between these variables and atrial ejection force was tested. Atrial ejection force was greater immediately and 24 hours after cardioversion in patients who had spontaneous recovery of sinus rhythm and in patients treated with drugs than in patients treated with DC shock. The mode of cardioversion was significantly associated with the recovery of atrial mechanical function by day 1 in univariate and multivariate analyses (odds ratio 0.14; 95% confidence interval 0.02 to 1.2). The other variable associated with the recovery of function was normal left atrial size (odds ratio 0.16; 95% confidence interval 0.12 to 1.6). In conclusion, atrial ejection force is a noninvasive parameter that can be easily measured and can provide accurate information about the recovery of left atrial mechanical function. The recovery of atrial function was influenced by the mode of cardioversion and the size of the left atrium.     

Response of atrial fibrillation to therapy: role of etiology and left atrial diameter

Left atrial diameter was measured by echocardiography in 107 patients in atrial fibrillation. The etiology of atrial fibrillation was rheumatic heart disease with predominant mitral valve involvement (RHD) in 51 patients and idiopathic atrial fibrillation (IAF) in 56. The left atrial diameter was correlated to the patient's response to therapy. The mean left atrial diameter was 3.4 cm in patients with paroxysmal atrial fibrillation, 3.8 cm in those requiring direct current (DC) cardioversion, and 4.4 cm in patients with persistent atrial fibrillation. However, in each of these therapeutic response groups, the left atrial diameter was signficantly smaller in patients with idiopathic atrial fibrillation. In the group with paroxysmal atrial fibrillation, the mean left atrial diameter was 4.3 +/- .7 cm in patients with RHD, compared to 3.1 +/- .6 cm in those with IAF (p less than .001). In the group requiring DC cardioversion, the left atrial diameter was 4.7 +/- .8 cm in patients with RHD compared to 3.6 +/- .5 cm in those with IAF (p less than .01). In patients with persistent atrial fibrillation, the left atrial diameter was 5.2 +/- .9 cm in patients with RHD and 4.0 +/- 1.0 cm in IAF (p less than .001). Left atrial diameter as well as the etiology of the heart disease are important in determining the response of atrial fibrillation to therapy.     

Role of autonomic reflexes in syncope associated with paroxysmal atrial fibrillation

OBJECTIVES: The purpose of this study was to evaluate the role of autonomic reflexes in the genesis of syncope associated with the onset of paroxysmal atrial fibrillation. BACKGROUND: Syncope associated with paroxysmal atrial fibrillation has been interpreted as an ominous finding predictive of rapid ventricular rates. However, various mechanisms may be involved when heart rate is not particularly high. METHODS: Forty patients (age 60 +/- 14 years, 20 men, 20 women) with syncope and atrial fibrillation were compared with atrial fibrillation without syncope. Carotid sinus massage and head-up tilt testing (at 60 degrees for 60 min at baseline and during isoproterenol infusion) were performed during sinus rhythm. A positive response was defined as the induction of syncope. Atrial fibrillation was also induced on a tilt table at 60 degrees by means of short bursts of atrial pacing. RESULTS: Results of carotid sinus massage were positive in 15 (37%) of 40 patients but in no control subjects (p = 0.002). Head-up tilt test findings were positive in 25 (66%) of 38 patients and in 2 (12%) of 16 control subjects (p = 0.0004). The induction of atrial fibrillation in the upright position elicited syncope in 16 (42%) of 38 patients but in none of 16 control subjects (p = 0.001). At the beginning of atrial fibrillation, systolic blood pressure was lower in patients than in control subjects (88 +/- 32 vs. 127 +/- 32 mm Hg), whereas mean heart rate was similar (142 +/- 35 vs. 134 +/- 25 beats/min). The correlation between heart rate and systolic blood pressure was weak (r = 0.35), and in five patients syncope occurred at a heart rate < or = 130 beats/min. At the time of syncope, heart rate decreased (-12 +/- 21 beats/min) in patients with induced syncope, whereas it remained unchanged in patients without induced syncope (+1 +/- 17 beats/min, p = 0.04) or slightly increased in control subjects (+9 +/- 21 beats/min, p = 0.009). CONCLUSIONS: Patients with syncope associated with paroxysmal atrial fibrillation are predisposed to an abnormal neural response during both sinus rhythm and arrhythmia. In some patients the onset of atrial fibrillation triggers vasovagal syncope.     

Drugs for conversion of atrial fibrillation

Atrial fibrillation is the most common arrhythmia in patients visiting a primary care practice. Although many patients with atrial fibrillation experience relief of symptoms with control of the heart rate, some patients require restoration of sinus rhythm. External direct current (DC) cardioversion is the most effective means of converting atrial fibrillation to sinus rhythm. Pharmacologic cardioversion, although less effective, offers an alternative to DC cardioversion. Several advances have been made in antiarrhythmic medications, including the development of ibutilide, a class III antiarrhythmic drug indicated for acute cardioversion of atrial fibrillation. Other methods of pharmacologic and nonpharmacologic cardioversion remain under development. Until the results of several large-scale randomized clinical trials are available, the decision to choose cardioversion or maintenance of sinus rhythm must be individualized, based on relief of symptoms and reduction of the morbidity and mortality associated with atrial fibrillation.     

The acute and 24-hour modifications to the atrial natriuretic factor in patients who have undergone mitral valvuloplasty. The hemodynamic and echocardiographic correlations

BACKGROUND: The recent introduction of percutaneous transvenous mitral valvuloplasty (PTMV) for the treatment of mitral stenosis (MS) has provided a unique human model for the study of short-term changes in ANF secretion before and after a reduction in left atrial pressure. This study was designed to investigate the effect of a short-term reduction in left atrial pressure and volume, as determined by echocardiographic study, on ANF and other neurohumoral factor plasma levels (renin and aldosterone). MATERIALS AND METHODS: 10 patients in III FC NYHA, with normal sinus rhythm and MS underwent PTMV. Hemodynamic parameters were measured immediately before and after (20-30 minutes) PTMV. Plasma levels of ANF, aldosterone and plasma renin activity (PRA) were obtained before (24 h) and after (2 h and 24 h) valvuloplasty; echocardiographic left atrial size before (24 h) and 24 h after PTMV. RESULTS: Immediately after PTMV mean left atrial (LA) pressure decreased from 22.3 +/- 6.8 mmHg to 10.0 +/- 2.4 mmHg (p < 0.01); mitral valve area (MVA) increased from 0.99 +/- 0.28 cm2 to 2.17 +/- 0.26 cm2 (p < 0.01). 24 hours after PTMV on echocardiography, LA systolic volume decreased from 59.5 +/- 16.9 cm3 to 42.3 +/- 8.3 cm3 (p < 0.01), LA diastolic volume from 82.6 +/- 15.8 cm3 to 66.5 +/- 12.6 cm3 (p < 0.01), and LA diameter from 48.1 +/- 7.5 mm to 39.2 +/- 4.4 mm (p < 0.01). ANF plasma levels before PTMV were 64.0 +/- 36.9 fmol/ml; 2 and 24 hours after PTMV they fell to 34.2 +/- 21.6 fmol/ml (p < 0.01) and to 20.3 +/- 21.0 fmol/ml (p < 0.01), respectively. PRA values were 15.7 +/- 13.2 ng/ml/h before PTMV; 2 and 24 hours after PTMV they increased to 17.5 +/- 23.2 ng/ml/h (NS) and to 22.3 +/- 16.8 ng/ml/h (p < 0.01). The aldosterone plasma levels were 43.2 +/- 27.9 ng/dl before PTMV and 47.3 +/- 35.8 ng/dl (NS) and 45.3 +/- 28.0 ng/dl (NS) 2 and 24 hours after PTMV. CONCLUSIONS: These results indicate that LA "de-stretching" due to the MVA increase and LA pressure decrease, leads to an abrupt reduction of ANF secretion. According to other studies, PRA increases immediately after PTMV, with a further increase 24 hours after PTMV.     

Actinic superficial folliculitis

BACKGROUND: The maze operation is effective for the restoration of sinus rhythm; however, restoration of atrial mechanical function has not been demonstrated in all patients. METHODS: Maze operations were performed in 32 patients (13 men, 19 women; mean age 47.1 +/- 9.0 years) combined with valvular surgery (n = 25), coronary artery bypass graft (CABG) (n = 3), and others (n = 4). At 1 week, 3 months, 6 months, and 1 year after the operation, prospective serial Doppler echocardiographic examination was carried out to determine the presence of atrial mechanical function. RESULTS: Sinus rhythm was restored and maintained during the follow-up period in 26 (81%) patients; in 22 patients this was due solely to the operation, whereas in four patients an antiarrhythmic agent was needed to maintain sinus rhythm. Another four patients showed paroxysmal atrial fibrillation (AF) despite treatment with an antiarrhythmic agent. Right atrial mechanical function was restored in all 30 patients with sinus rhythm or paroxysmal AF; in 19 (63%) of these, left atrial mechanical function was restored. In patients with restored left atrial mechanical function, peak A velocity (A) and A/E ratio (A/E) of mitral inflow were significantly lower than in the 16 postoperative control patients (A: 0.46 +/- 0.14 m/sec vs 0. 75 +/- 0.29 m/sec, p < 0.01; A/E: 0.40 vs 0.80, p < 0.01). In patients with left atrial mechanical function, the duration of AF was significantly shorter than in patients without left atrial mechanical function (1.9 +/- 2.9 years vs 7.1 +/- 3.0 years, p < 0. 01), but there were no significant differences in left atrial size and volume. CONCLUSIONS: The maze operation could be safely added to standard open heart surgery for the correction of underlying structural heart disease. The rate of conversion to sinus rhythm resulting solely from the operation might be lower than the rates previously reported with only the duration of AF adversely affecting the restoration of left atrial mechanical function. Considering the fact that not all patients converted to sinus rhythm show atrial mechanical function, the role of the maze operation in the prevention of systemic embolism, with subsequent improvement in survival, requires further study.