Abstract

GONZALEZ, G. E. et al. Comportamiento diastólico durante la fase de "hipercontracción" post- isquémica en el miocardio atontado de conejo. Medicina (B. Aires) [online]. 2003, vol.63, n.5, pp.403-409. ISSN 0025-7680.

The objective was to determine whether "hypercontraction" (HC) that occurs at the beginning of reperfusion (R) in stunned myocardium is accompanied by diastolic alterations and determine if the R with low Ca2+ Ringer's solution modifies these alterations. Isolated isovolumic rabbit hearts were divided into 2 groups. Group 1 (G1, n=11) was perfused with Ringer's solution ([Ca2+]=2mM) and subjected to 15min of global ischemia and 30min of R. Group 2 (G2, n=10) was R during the first 10 min with ([Ca2+ ]=1mM), which was increased to 1.5 mM and 2 mM in the perfusate at 30 min of R. The left ventricular +dP/dtmáx, left ventricular end diastolic pressure (LVEDP) (stiffness index), and relaxation rate (t1/2 and +P/-P ratio) were measured, from the beginning of R every 10sec for 2min, and then at 5 and 30min. At 60 sec of R the +dP/dtmáx in G1 was increased (76,88±5,37% vs preischemic value) and was attenuated in G2 (48,22±3,40%; P<0.05 vs G1). The LVEDP in G1 was increased early in the R, although it was negatively correlated with HC degree (r=-0.7477; p=0.008). This increase was attenuated in G2 (P<0.05 vs G1) at 60 secR. There was a delay in the relaxation at 60 secR in both group (G1 vs G2, NS). In conclusion: HC is accompanied by diastolic alterations. The improvement of HC is inversely related with LVEDP. During R the stiffness during the relaxation rate was normal. The R with low Ca2+ attenuated the HC and the diastolic stiffness.

Keywords : Ischemia; Stunned myocardium; Post-ischemic hypercontraction; Low calcium.

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