Sanguineous normothermic, intermittent cardioplegia, effects on hypertrophic myocardium. Morphometric, metabolic and ultrastructural studies in rabbits hearts

Abstract

Sanguineous normothermic, intermittent cardioplegia, effects on hypertrophic myocardium. Morphometric, metabolic and ultrastructural studies in rabbits hearts Abstract Objectives: The present investigation aimed to study the protective effect of intermittent normothermic cardioplegia in rabbit's hypertrophic hearts.Methods: The parameters chosen were 1) the ratio heart weight / body weight, 2) the myocardial glycogen levels, 3) ultrastructural changes of light and electron microscopy, and 4) mitochondrial respiration.Results: 1) The experimental model, coarctation of the aorta induced left ventricular hypertrophy; 2) the temporal evolution of the glycogen levels in hypertrophic myocardium demonstrates that there is a significant decrease; 3) It was observed a time-dependent trend of higher oxygen consumption values in the hypertrophic group; 4) there was a significant time-dependent decrease in the respiratory coefficient rate in the hypertrophic group; 5) the stoichiometries values of the ADP: O2 revealed the downward trend of the values of the hypertrophic group; 6) It was possible to observe damaged mitochondria from hypertrophic myocardium emphasizing the large heterogeneity of data.Conclusion: The acquisition of biochemical data, especially the increase in speed of glycogen breakdown, when anatomical changes are not detected, represents an important result even when considering all the difficulties inherent in the process of translating experimental results into clinical practice. With regard to the adopted methods, it is clear that morphometric methods are less specific. Otherwise, the biochemical data allow detecting alterations of glycogen concentrations and mitochondria respiration before the morphometric alterations should be detected Descriptors: Heart arrest, induced. Hypertrophy, left ventricular. Cardiovascular surgical procedures. 622Rev Bras Cir Cardiovasc 2012;27(4):621- INTRODUCTIONThe current success of cardiac surgery was provided, among other relevant factors, by better understanding the myocardium protection. The timeline of this understanding includes: 1) systemic hypothermia [1]; 2) intra-operative cardiac arrest induced by potassium citrate [2]; 3) anoxic arrest of the heart [3]; 4) the use of chemicals that could rapidly determine cardiac arrest [4]; 5) Miscellaneous studies relating to the composition, temperature and mode of drug administration named cardioplegic solution [5][6][7], and; 6) normothermic cardioplegia [8,9].In cardiac hypertrophy, whether it is induced in an experimental model or observed clinically, energy metabolism is compromised highlighting that Sink et al.[10] demonstrated that the hypertrophic heart must be stopped immediately emphasizing the need of additives to the cardioplegia solution. It is noteworthy that Cooley et al., in 1972, described the "Stone Heart", i.e., ischemic contracture, more frequent and severe in the hypertrophic heart [11]. This ischemia/reperfusion phenomenon allowed the resumption of the discussion, and final conclusion, about the pivota...