IntroductionAlthough rare, the atrioesophageal fistula is one of the most feared complications in radiofrequency catheter ablation of atrial fibrillation due to the high risk of mortality.ObjectiveThis is a prospective controlled study, performed during regular radiofrequency catheter ablation of atrial fibrillation, to test whether esophageal displacement by handling the transesophageal echocardiography transducer could be used for esophageal protection.MethodsSeven hundred and four patients (158 F/546M [22.4%/77.6%]; 52.8±14 [17-84] years old), with mean EF of 0.66±0.8 and drug-refractory atrial fibrillation were submitted to hybrid radiofrequency catheter ablation (conventional pulmonary vein isolation plus AF-Nests and background tachycardia ablation) with displacement of the esophagus as far as possible from the radiofrequency target by transesophageal echocardiography transducer handling. The esophageal luminal temperature was monitored without and with displacement in 25 patients.ResultsThe mean esophageal displacement was 4 to 9.1cm (5.9±0.8 cm). In 680 of the 704 patients (96.6%), it was enough to allow complete and safe radiofrequency delivery (30W/40ºC/irrigated catheter or 50W/60ºC/8 mm catheter) without esophagus overlapping. The mean esophageal luminal temperature changes with versus without esophageal displacement were 0.11±0.13ºC versus 1.1±0.4ºC respectively, P<0.01. The radiofrequency had to be halted in 68% of the patients without esophageal displacement because of esophageal luminal temperature increase. There was no incidence of atrioesophageal fistula suspected or confirmed. Only two superficial bleeding caused by transesophageal echocardiography transducer insertion were observed.ConclusionMechanical esophageal displacement by transesophageal echocardiography transducer during radiofrequency catheter ablation was able to prevent a rise in esophageal luminal temperature, helping to avoid esophageal thermal lesion. In most cases, the esophageal displacement was sufficient to allow safe radiofrequency application without esophagus overlapping, being a convenient alternative in reducing the risk of atrioesophageal fistula.

Despite having a huge benefit in enabling heart rate control, cardiac pacing by stimulating the right ventricular apex causes an artificial iatrogenic left bundle-branch block-like syndrome. As a result, QRS widening and cardiac wall desynchronization occurs. The problems caused by this undesirable pacemaker side effect have been ignored, as they are counteracted by the great benefit of cardiac rate correction. However, the compelling evidence about its harmful effect presented in this article cannot be disregarded and should start an attitude change toward alternate sites of ventricular pacing and preclusion of the right ventricular apex stimulation.

The SM in sinus rhythm can be used in the ablation of AF nests. During the AF, the AF nests present a reactive-resonant pattern and the compact myocardium is passive, stimulated by the high frequency of the BT. After the ablation of the AF nests and the BT, it was not possible to reinduce the sustained AF. The Ablation of AF nests outside the pulmonary veins showed to be safe and highly effective in the cure and/or clinical control of the AF.

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Objective -To describe a new more efficient method of endocardial cardiac stimulation, which produces a narrower QRS without using the coronary sinus or cardiac veins. In dilated cardiomyopathy some degree of delay occurs in myocardial stimulus conduction, which causes QRS widening. Associated lesions in the conduction system also often cause QRS widening. In these cases, when a cardiac pacemaker is necessary, paced QRS is more enlarged, easily achieving 200 ms or even more. The delayed ventricular activation, by itself, provokes systolic and diastolic dysfunction, and increases mitral regurgitation 1 . Since the beginning of cardiac pacing, it has been known that the contraction caused by a paced QRS is less effective than the one resulting from a normal QRS. When the QRS is wide, the increased pressure caused by the first stimulated myocardium area is lessened by the natural complacence of other areas that will be activated later. On the other hand, in the normal contraction, the fast myocardial cell activation creates a mechanical synergism, extremely favorable for taking maximum advantage of the inotropic state. It causes a pressure wave with high dP/dt, which is a faster, highly efficient rise in pressure. In the dilated myocardium, the activation generated by a pacemaker is distributed over a longer time, causing a pressure wave that is more attenuated proportionally to the paced QRS widening. To preserve systolic and diastolic functions, and reduce mitral insufficiency, it appears to be fundamental to pace both ventricles with a normal QRS, or at least with the shortest PRS possible. This can be easily obtained by AAI pacing, when the patient has intra-and atrioventricular conduction systems preserved. In the case of AV block, the resulting ventricular paced QRS (almost always placed on the right ventricle) is very wide. It is possible to have a narrow QRS simultaneously pacing more than one point. Recent studies have shown narrow QRS and improved myocardial contractility, when both ventricles are simultaneously paced 2 . The problem is access to the left ventricle. The first approach was epicardial, which requires a thoracotomy 3 . The alternative is the use of cardiac veins; through the coronary sinus. This method avoids thoracoto- Methods -