[Usefulness of Doppler echocardiography in the analysis of left ventricular isometric relaxation time in an experimental model of myocardial reperfusion]. / Utilidad del eco/Doppler para el análisis del tiempo de relajación isométrica del ventrículo izquierdo en un modelo experimental de reperfusión miocárdica.

UNLABELLED: Modifications of left ventricular isometric relaxation time (LVIRT) were analyzed in an experimental model of myocardial reperfusion (MR). In a prospective study, 19 mongrel dogs were studied with open chest, mechanical ventilation and hemodynamic monitoring. A catheter was inserted in the middle third of the anterior descending artery (ADA) for registry of its pressure. The ADA was ligated distal to the first diagonal branch for 15 min and subsequently untied. Epicardial Echo/Doppler registries were obtained in basal conditions, at 5 and 15 min of ischemia and at 5, 15, 30 and 60 min after MR. Mobility and changes in thickness of the interventricular septum (IVS) were analyzed, and LVIRT was measured in all of the periods mentioned. There were no significant changes in the thickness of IVS. LVIRT increased in comparison to the basal registry at 5 and 15 min of ischemia (p < 0.0001) and returned to basal values with MR (p < 0.05). CONCLUSIONS: Acute myocardial ischemia prolongs LVIRT, in this model, during MRLVIRT returned to normal. In the experimental model, measurement of LVIRT may be used as criterion for reperfusion.