ANDERSON CARVALHO DA SILVA

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Instituto Central, Hospital das Clínicas, Faculdade de Medicina

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  • article 13 Citação(ões) na Scopus
    Accelerated conversion of atrial fibrillation to normal sinus rhythm by pulmonary delivery of flecainide acetate in a porcine model
    (2018) VERRIER, Richard L.; BORTOLOTTO, Alexandre L.; SILVA, Bruna A.; MARUM, Alexandre A.; STOCCO, Fernando G.; EVARISTO, Ederson; ANTONIO, Victor Z. de; SILVA, Anderson C.; BELARDINELLI, Luiz
    BACKGROUND Pulmonary delivery of antiarrhythmic agents has the potential to increase rapidly targeted drug concentrations in pulmonary veins and left atrium to terminate atrial fibrillation (AF). OBJECTIVE We evaluated the efficacy of flecainide administered via intratracheal instillation in terminating AF in a reliable preclinical model. METHODS In 11 closed-chest anesthetized Yorkshire pigs, AF was induced by intrapericardial administration of acetylcholine (1 mL of 102.5 mM solution) followed by burst pacing and allowed to continue for 2 minutes before intratracheal flecainide (0.4 or 0.75 mg/kg) administration. RESULTS Both the 0.4-and 0.75-mg/kg doses of intratracheal flecainide significantly reduced AF duration by 35% (P = .02) and 54% (P = .001), respectively, compared to no-drug baseline. There was a strong inverse correlation (r(2) = 0.87; P = .03) between the duration of AF and the change in atrial depolarization duration in response to intratracheal flecainide. Induction of AF resulted in a marked increase in ventricular rate and corresponding reduction in mean arterial pressure, which returned to baseline levels within 5 minutes after conversion. CONCLUSION Intratracheal flecainide instillation is effective in rapidly converting AF to normal sinus rhythm and restoring mean arterial pressure and heart rate to baseline values. The basis for this efficacy is likely rapid absorption of the drug through the lungs and delivery as a first-pass bolus to the left atrial and ventricular chambers and then to the coronary arterial circulation. The antiAF effect of flecainide is inversely correlated with the drug's prolongation of atrial depolarization, implicating slowing of intra-atrial conduction as an important mechanism underlying conversion of AF to normal sinus rhythm.
  • article 7 Citação(ões) na Scopus
    Pulmonary delivery of flecainide causes a rate-dependent predominant effect on atrial compared with ventricular depolarization duration revealed by intracardiac recordings in an intact porcine model
    (2018) ANTONIO, Victor Z. de; SILVA, Anderson C.; STOCCO, Fernando G.; SILVA, Bruna A.; MARUM, Alexandre A.; BORTOLOTTO, Alexandre L.; BELARDINELLI, Luiz; VERRIER, Richard L.
    Background Pulmonary delivery of flecainide results in the rapid conversion of atrial fibrillation (AF) to normal sinus rhythm in large-animal models and is safe and well-tolerated by normal human volunteers. Objective Methods We investigated the effects of pulmonary delivery of flecainide on atrial and ventricular depolarization and repolarization duration. Intratracheal instillation (1.5 mg/kg, rapid push) of flecainide or sterile water (placebo) was performed in 12 closed-chest, anesthetized Yorkshire pigs with a catheter positioned at the bifurcation of the main bronchi. High-resolution electrograms obtained from catheters fluoroscopically positioned in the right atrium and left ventricle circumvented measurement errors due to the fusion of P and T waves in surface leads when rapid heart rates shortened the TP interval. Pacing was achieved using electrical stimuli delivered via right atrial catheter electrodes. Results Conclusion During sinus rhythm (98 +/- 4.7 beats/min), intratracheal flecainide caused comparable (P = 0.56) increases in atrial depolarization (P-a) duration by 22% (39.8 +/- 3.2 to 48.7 +/- 3.3 milliseconds) and left ventricular (LV) QRS complex duration by 20% (47.9 +/- 1.6 to 57.3 +/- 1.8 milliseconds) at peak effect at 2 minutes post-dosing. During right atrial pacing at 180 beats/min, P-a duration increased by 55% (37.0 +/- 2.0 to 57.2 +/- 1.6 milliseconds; P < 0.0001). The atrial response was greater (p = 0.001) than the 30% increase in LV QRS complex duration (46.6 +/- 1.7 to 60.6 +/- 2.5 milliseconds; P = 0.005). P-a duration and QRS complex duration were unchanged by placebo independent of pacing (P >= 0.4 for both). Atrial repolarization duration (PTa; P = 0.46) and QT(c) interval (P = 0.49) remained unchanged. Intratracheal flecainide exerts a rate-dependent, predominant effect on atrial compared with ventricular depolarization duration. Pulmonary delivery of flecainide could facilitate AF conversion to sinus rhythm with reduced ventricular proarrhythmia risk.
  • article 8 Citação(ões) na Scopus
    Optimizing flecainide plasma concentration profile for atrial fibrillation conversion while minimizing adverse ventricular effects by rapid, low-dose intratracheal or intravenous administration
    (2019) MARUM, Alexandre A.; SILVA, Bruna A.; BORTOLOTTO, Alexandre L.; SILVA, Anderson C.; ANTONIO, Victor Z. de; BELARDINELLI, Luiz; VERRIER, Richard L.
    Background: We investigated whether rapid administration of a low dose of flecainide, either intratracheally or intravenously (IV), could accelerate conversion of atrial fibrillation (AF) while reducing adverse ventricular effects. Methods: Flecainide was delivered via intratracheal administration at 1.5 mg/kg bolus and compared to IV infusion at 1.0 mg/kg over 2 min (lower-dose, rapid) and 2.0 mg/kg over 10 min (ESC guideline) in closed-chest, anesthetized Yorkshire pigs. Catheters were fluoroscopically positioned in right atrium to measure atrial depolarization (P-a) duration and left ventricle (LV) to measure QRS complex duration and contractility (LV dP/dt) during atrial pacing at 140 beats/min. Flecainide was delivered intratracheally via a catheter positioned at the bifurcation of the main bronchi. AF was induced by intrapericardial administration of acetylcholine followed by burst pacing. Results: Flecainide reduced AF duration similarly by intratracheal and IV delivery. Peak plasma levels were comparable but T-max differed and coincided with peaks in P-a prolongation. The area under the curve indicating sustained plasma levels was greater for higher-dose, slow IV flecainide than for either intratracheal instillation (by 32%) or lower-dose, rapid IV infusion (by 88%). As a result, higher-dose, slow IV flecainide caused 58% (p < 0.03) and 48% (p < 0.006) greater increases in QRS complex duration and 61% and 96% (both, p < 0.02) greater reductions in contractility compared to intratracheal and lower-dose, rapid IV flecainide, respectively. Conclusion: Lower-dose, rapid flecainide, delivered either intratracheally or IV, optimizes the plasma concentration profile for effective conversion of AF while minimizing adverse effects on QRS complex duration and LV contractility.