Abstract

ZOCALO, YANINA et al. Contrapulsación intraaórtica y determinantes de la poscarga ventricular: estudio experimental en un modelo animal Cambios en resistencias periféricas, impedancia y elasticidad aórtica y características propagatorias del pulso durante latidos asistidos. Rev.Urug.Cardiol. [online]. 2006, vol.21, n.3, pp.204-217. ISSN 1688-0420.

SUMMARY Introduction: the intraortic balloon pump (IABP) benefits have been ascribed mainly to the haemodynamic effects (pressure and vascular resistance changes) determined by the balloon inflate-deflate cycle. The ventricle dynamic afterload depends on the aortic elasticity and impedance, and on the pulse wave propagation velocity and peripheral reflexion level. The IABP effects on the dynamic afterload and/or their mechanisms (passive and/or active) remain to be characterized. Objective: to characterize the changes in the dynamic and static afterload determinants during the IABP assistance, and the mechanisms (active and/or passive) that determine those changes. Methods: in 8 sheep aortic flow, diameter and pressure were measured in basal (control) and assisted (post-augmented) beats, during the IABP assistance in the 1:2 modality. The peripheral vascular resistance, aortic elasticity and impedance, pulse wave velocity, peripheral reflexion coeficient and the propagative-mismatch index were calculated. Isobaric comparisons between basal and assisted beats were performed so as to characterize the smooth muscle activation dependent changes. Results: during the assistance the expected haemodynamic changes were obtained. The aortic diameter and elasticity, the peripheral reflexion, propagative-mismatch index and vascular resistance were lower in the assisted beats than in the basal conditions (p<0,05). Despite of the geometrical differences, the impedance and propagation velocity were similar between the assisted and basal beats. Conclusion: the determinants of the dynamic and static ventricle afterload determinants were reduced during the IABP assistance. The effects would depend on smooth muscle-dependent mechanisms.

Keywords :   INTRA-AORTIC CONTRAPULSATION; ELASTICITY; REFLEXION INDEX; IMPEDANCE; SMOOTH MUSCLE; DYNAMIC VENTRICLE AFTERLOAD; PULSE WAVE VELOCITY.

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