Nota: Estas diretrizes se prestam a informar e não a substituir o julgamento clínico do médico que, em última análise, deve determinar o tratamento apropriado para seus pacientes.

DEDICATÓRIA DedicoAos meus pais, Manuel e Dirma, que sempre me incentivaram no caminho dos estudos.Ao meu irmão Caio, pelos conselhos sempre úteis.Ao meu filho Thiago, um enorme motivador para esta caminhada.À Eliana, minha esposa, que sempre incentivou este trabalho, com muita compreensão.

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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 -

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