Ebstein's anomaly with refractory atrial tachycardia

The incidence of accessory pathways in patients with Ebstein's anomaly is high, ranging from 20% to 30%, with right and multiple pathways being more commonly encountered. Radiofrequency ablation can eliminate the accessory pathway, but success rates of ablation treatment and the chances of recurrence are generally less satisfactory as compared to those observed when the procedure is performed on structurally normal hearts. We report the case of a 56-year-old man with Ebstein's anomaly and refractory atrial tachycardia. The special abnormality of the tricuspid valve led to the failure of preoperative electrophysiological mapping and radiofrequency ablation treatment. Finally, the anomalies observed in this patient were corrected with simultaneous surgery and pathway resection.     

Repeated cardioversion during pregnancy. Treatment of refractory paroxysmal atrial tachycardia during 3 successive pregnancies

Multiple cardioversions for the treatment of refractory paroxysmal atrial tachycardia were performed during various stages of 3 pregnancies in a patient with no evidence of organic disease. All 3 babies were delivered with no abnormalities. It appears that this method of therapy is safe and effective for treating refractory arrhythmias during pregnancy.     

Mechanism and mapping of atrial arrhythmia in the modified Fontan circulation.

The Fontan circulation has been a major success in the management of patients with functionally single-ventricle cardiac lesions, although arrhythmia remains one of the major complications in the long term and historically has been difficult to treat. The electrophysiologic substrate within the right atrium is complex, with areas of scarring and/or anatomic structures acting as central barriers to conduction in reentrant circuits, which may be mechanistically and anatomically different from typical atrial flutter. Developments in three-dimensional mapping have improved our understanding of different arrhythmia mechanisms, which is fundamental to developing a better strategy for arrhythmia ablation using percutaneous techniques.     

Ethanol infusion in left atrial appendage vein for treating refractory left atrial appendage tachycardia

Introduction

We describe an unusual case of atrial tachycardia (AT) emanating from the left atrial appendage body (LAA), successfully treated by chemical ablation.

Methods

A 66-year-old patient with cardiac amyloidosis and history of persistent atrial fibrillation ablation presented poorly tolerated AT with 1:1 atrioventricular nodal conduction at 135/min, despite amiodarone therapy. Three-dimensional mapping suggested a reentrant AT from the anterior aspect of the left LAA.

Results

The tachycardia could not be terminated with radiofrequency ablation. The LAA vein was then selectively catheterized and infused with Ethanol, resulting in immediate termination of tachycardia, without LAA isolation. No recurrence occurred at 12 months.

Conclusion

Atrial tachycardias emanating from the LAA that are resistant to radiofrequency ablation may respond to chemical ablation of the LAA vein.     

Patients with paroxysmal atrial fibrillation but not paroxysmal supraventricular tachycardia display evidence of platelet activation during arrhythmia

It is well known that chronic atrial fibrillation (CAF) and paroxysmal atrial fibrillation (PAF) are associated with a hypercoagulable state. However, pathological hemostatic changes during the paroxysmal supraventricular tachycardia (PSVT) have not yet been elucidated. To determine platelet activity in patients with PSVT, PAF and CAF, we examined the levels of β-thromboglobulin (BTG) and platelet factor 4 (PF4) during tachyarrhythmia attacks. We measured the levels of BTG and PF4, as an index of platelet activation in 15 patients with PAF (9 men, mean age 45 ± 11), and 14 patients with PSVT (8 men, mean age 40 ± 10). Levels were compared to 22 age and sex-matched healthy controls in sinus rhythm and with 25 patients with CAF (16 men, mean age 51 ± 12). Blood samples were taken during arrhythmia and 24 hours after conversion to sinus rhythm. Patients taking medications or have clinical conditions that may affect the BTG and PF4 levels were excluded.

In patients with PAF, BTG and PF4 levels were significantly higher than in controls (?p<0.009, and p = 0.002, respectively), and in patients with PSVT (?p<0.04, and p = 0.009, respectively), however, BTG and PF4 levels were significantly lower than CAF patients (?p = 0.002, and p = 0.02, respectively). Moreover, BTG and PF4 levels were significantly decreased 24 hours after conversion to sinus rhythm (?p<0.0001, and p = 0.004, respectively). Although BTG and PF4 levels in patients with PSVT were significantly lower than in patients with PAF (?p = 0.04, and p = 0.009, respectively) and CAF (?p = 0.0001, and p = 0.0001, respectively), BTG and PF4 levels were similar to controls and did not change significantly after recovery to sinus rhythm (?p = NS for all).

These results indicate that there was no platelet activation in patients with PSVT during tachyarrhythmia but significantly increased platelet activity in PAF and CAF patients. There was a significant decrement of the platelet activity to a level of control subjects twenty-four hours after cardioversion of PAF.     

Acute results of transvenous cryoablation of supraventricular tachycardia (atrial fibrillation,atrial flutter,Wolff-Parkinson-White syndrome,atrioventricular nodal reentry tachycardia)

INTRODUCTION: Radiofrequency (RF) catheter ablation currently is used for treatment of cardiac arrhythmias. Although the success rate is high for almost all supraventricular tachycardias (SVT), this technique has some drawbacks, especially when pulmonary veins (PV) are targeted for treatment of atrial fibrillation (AF). Additionally, new techniques for isolation of the PVs have the drawback that they can be used only for PV isolation and not for routine treatment of other SVTs. The aim of this study was to report on the safety and efficacy of a new cryoablation system for treatment of all SVTs. METHODS AND RESULTS: Forty-nine patients with SVT (38 men; age 48 years, range 23-76) were enrolled in the study. Five patients were withdrawn from the study before they underwent cryoablation. The remaining 44 patients were treated with cryoablation (22 AF, 15 atrial flutter, 3 accessory pathway, 2 AV nodal reentrant tachycardia, 1 AV junction ablation for permanent AF, 1 atrial tachycardia). Cryoablation was performed with the CryoCor cryoablation system, which uses a precooling system and N2O as a refrigerant. The number of freezes applied varied according to the index arrhythmia treated. Successful isolation of PVs was performed in 20 of (96%) 21 AF patients and 53 of 55 veins. The overall acute success was 98% (43/44). Fifty-three PVs were isolated (2.5/patient). The success rate was 100% (23/23) for right-sided procedures. The average and nadir temperatures reached in right-sided and left-sided procedures were -77 degrees C and -80 degrees C and -75 degrees C and -78 degrees C, respectively. No acute PV stenosis was seen. CONCLUSION: This novel cryoablation system appears to be safe and can successfully treat different types of SVTs, including AF. Isolation of PVs is possible without producing stenosis. Despite the high blood flow in the right atrial isthmus and PVs, bidirectional conduction block can be achieved.     

Patients with paroxysmal atrial fibrillation but not paroxysmal supraventricular tachycardia display evidence of platelet activation during arrhythmia

It is well known that chronic atrial fibrillation (CAF) and paroxysmal atrial fibrillation (PAF) are associated with hypercoagulable state. However, pathological hemostatic changes during the paroxysmal supraventricular tachycardia (PSVT) have not yet been elucidated. To determine platelet activity in patients with PSVT, PAF and CAF, we examined the levels of beta-thromboglobulin (BTG) and platelet factor 4 (PF4) during tachyarrhythmia attacks. We measured the levels of BTG and PF4, as an index of platelet activation in 15 patients with PAF (9 men, mean age 45+/-11), and 14 patients with PSVT (8 men, mean age 40+/-10). Levels were compared to 22 age and sex matched healthy controls in sinus rhythm and with 25 patients with CAF (16 men, mean age 51+/-12). Blood samples were taken during arrhythmia and 24 hours after conversion to sinus rhythm. Patients taking medications or have clinical conditions that may affect the BTG and PF4 levels were excluded. In patients with PAF, BTG and PF4 levels were significantly higher than in controls (p<0.009, and p=0.002, respectively), and in patients with PSVT (p<0.004, and p=0.009, respectively), however, BTG and PF4 levels were significantly lower than CAF patients (p=0.002, and p=0.02, respectively). Moreover, BTG and PF4 levels were significantly decreased 24 hours after conversion to sinus rhythm (p<0.0001), and p=0.004, respectively). Although BTG and PF4 levels in patients with PSVT were significantly lower than in patients with PAF (p=0.04, and p=0.009, respectively) and CAF (p=0.0001, and p=0.0001, respectively), BTG and PF4 levels were similar to controls and did not change significantly after recovery to sinus rhythm (p=NS for all). These results indicate that there was no platelet activation in patients with PSVT during tachyarrhythmia but significantly increased platelet activity in PAF and CAF patients. There was a significant decrement of the platelet activity to a level of control subjects twenty-four hours after cardioversion of PAF.     

房室结折返性心动过速冷冻消融术中快径有效不应期的改变

目的对冷冻消融治疗房室结折返性心动过速(AVNRT)术中快径有效不应期(FPERP)改变的生理现象进行探讨。方法对26例冷冻消融治疗AVNRT患者行术前、有效靶点冷冻消融术中及术后电生理检查,记录FPERP及AH间期的改变。结果 26例AVNRT患者冷冻消融均成功阻断慢径。共35处有效靶点消融术中可见FPERP较术前暂时性延长(386.29±67.65msvs330.29±71.80ms,P0.05),术后立即恢复(301.14±73.24msvs330.29±71.80ms,P0.05),同时AH间期术后较术前无改变(83.80±12.24msvs77.77±12.52ms,P0.2)。结论 AVNRT冷冻消融慢径术中FPERP暂时性延长,停止消融即刻恢复。     

Emergency transvenous ablation of atrioventricular conduction to control refractory atrial tachycardia

Three patients were referred for urgent investigation and treatmentof refractory arrhythmias. Each patient had failed to respondto antiarrhythmic drugs and in two patients direct current cardioversionwas also unsuccessful. Transvenous ablation of atrioventricularconduction was therefore thought appropriate. With a temporaryventricular pacing system in situ, a second electrode was usedto record His and atrial electro-grams. A 270 watt-second shockwas delivered through this lead when the His potential was maximized.The tachycardia was controlled in two patients and the procedurewas without deleterious effects.