Biodegradable polymeric microspheres can be used to deliver drugs through controlled rate and targeted processes. The drug is released from the particles by drug leaching or degradation of the polymeric matrix. Crystallinity can play a very important role in the degradation of polymeric matrixes; it can affect the drug-release rate, especially in chemoembolization. Most commercial embolic agents have a low degree of crystallinity, and the correlation between the drug-delivery rate and the degree of crystallinity is not fully understood. This study presents the appropriated synthesis conditions for the preparation of highly crystalline poly(vinyl alcohol) and poly(vinyl alcohol)/poly(vinyl acetate) microspheres and physicochemical characterizations by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, and cross-polarization/magic angle spinning nuclear magnetic resonance.

The myocardial protection allowed great advance in cardiac surgery, decreasing the mortality and making more feasible complex surgeries. Latterly the patient population elected for cardiac procedures has been changing towards elderly patients with ventricular function depressed and myocardial hypertrophy. The myocardial hypertrophy condition represents a great challenge since the beginning of the cardiac surgery. Several techniques have been described to protect the myocardial hypertrophy, however with no satisfactory results. In this manuscript we present the state of the art technique of myocardial protection. 98CRESSONI, ES ET AL -Myocardial protection to the hypertrophied heart: the eternal challenge Bras Cir Cardiovasc 2008; 23(1): 97-107 Rev

The meaning of the term "cardioplegia" is "lesion, attack, wound or blow", very different to how it is most commonly understood in most heart centers, where it relates to cardiac protection. Thus, "cardioplegic solution" is better defined as a solution capable of inducing controlled cardiac arrest. Cardiac arrest induced by cardioplegic solutions can occur by hyperpolarization, depolarization or by inhibiting the calcium channels of the myocardial fibers. This paper discusses hyperpolarizing cardioplegic solutions, which arrest the heart in the diastolic phase, thus decreasing the ATP depletion and improving the conditions of the heart to be reanimated at the end of the procedure.

Efeitos das cardioplegias sangüínea e cristalóide no miocárdio hipertrófico de coelho: avaliação estrutural e ultra-estruturalEffects of myocardial protection on hypertrophic rabbit hearts: structural and ultra structural analysis Abstract Objective: To experimentally compare the structural and ultrastructural changes in isolated hypertrophied rabbits' hearts submitted to cardiac arrest protected using blood and crystalloid cardioplegia solutions.Method: The study comprised two experimental groups and one control group. In Experimental Group I, cardiac arrest was achieved by the continuous infusion of a tepid blood cardioplegia solution. In Experimental Group II, cardiac arrest was obtained by an intermittent infusion of a cold crystalloid cardioplegia solution. In the Control Group the hearts were submitted to normothermic anoxic arrest for 45 minutes. After the procedures, eight samples of the left ventricle lateral wall were collected and fixed in 10% formaldehyde and 2.5% glutaraldehyde for structural and ultrastructural analysis. Results:The structural and ultrastructural results demonstrated that the hearts submitted to cardiac arrest protected by continuous tepid blood cardioplegia, Group I, were better preserved and with less accentuated cellular alterations compared to those submitted to cardiac arrest protected using intermittent cold crystalloid cardioplegia and the Control Group.Conclusion: Continuous tepid blood cardioplegia was more efficient in the preservation of the structural and ultrastructural integrity of the myocardium when compared to intermittent cold crystalloid cardioplegia.Descriptors: Cardioplegic solutions, pharmacology. Hypertrophy. Cardiac surgical procedures. 25CRESSONI, ES ET AL -Effects of myocardial protection on hypertrophic rabbit hearts: structural and ultra structural analysis Braz J Cardiovasc Surg 2007; 22(1): 24-32 membrane polarized cardioplegia with tetrodotoxin, esmolol and other formulas [15].Thus, the current work aims at evaluating structural and ultrastructural alterations occurring after the use of blood and crystalloid cardioplegic solutions in hypertrophic myocardium of rabbits. METHODNine Norfolk-2000 rabbits variant Botucatu of both genders were utilized with weights ranging from 1850 to 2350 kg, all supplied by the animal house on the Campus of Botucatu -UNESP. The research was approved by the Research Ethics Committee of the Medical School in Botucatu -UNESP. Conditioning of myocardial hypertrophyAfter general anesthesia of the animal using sodium pentobarbital, a crosswise incision was performed in the cervical region, slightly above the sternum. The aortic artery was identified, pericardiotomy was performed and the ascending aorta was isolated and coarctation was provoked using the technique described by Martins et al. [16]. After 5 months with hypertrophic hearts (Figure 1), the animals were euthanized. INTRODUCTIONHypertension is the greatest cause of left ventricle hypertrophy [1], affecting around one third of the hypertensive population [2], leadi...

AbstractsIntroduction: Pharmacological cardioplegic solution aims to eliminate the consequences of ischemic damage, which results from the misbalance between the offer and consumption of energy during the arrest of the heart beats during cardiac surgery with cardiopulmonary bypass.Objectives: This research experimentally evaluates the structural and ultrastructural changes in isolated rabbit hearts submitted to arrest protected by a Low Volumetric Cardioplegic Solution (LVCS).Material and Method: The study counted with a control group and two experimental groups. In group I the cardiac arrest was obtained by infusion of the LVCS for 2 hours.In group II the experiment was conducted in the same way until the arrest protected by LVCS for 2 hours, and immediately after reperfusion was performed with the Ringer Locke (RL) oxygenated solution for 1 hour. In the control group the hearts were perfused with the RL oxygenated solution for 2 hours. After the experiments, 8 samples of the left ventricle were fixed in 10% formaldehyde and 2.5% glutaraldehyde for histological and ultrastructural analysis.Results: The myocardial cells, the fibroblasts and the endothelial cells which were observed in the experimental groups I and II, presented with marginalization of the heterochromatin, compaction of the nucleolus, change in the morphology of the mitochondria and compaction of the cristae. Also there was an increase of the density of the mitochondrial matrix. This indicates that the nuclear structure as well as the structure of the cytoplasmic organelles were altered when compared to the cells of the control group.Conclusion: The structural modifications were due a physiological adaptation of the cell, and not an indication of oncosis or apoptosis, suggesting that the cardioplegic solution used was efficient for the preservation of the cells.