Heraldo Guedis Lobo Filho

Experimental model of myocardial infarction induced by isoproterenol in rats

OBJECTIVE: To evaluate and validate, in our laboratory, the essay of myocardial infarction induced by isoproterenol in rats by means of analysis of hematological, biochemical, oxidative stress markers and histopathological parameters. METHODS: Thirty young, male, Wistar rats (145 to 230 g) were randomly allocated in two groups: Sham group, which underwent a virtual myocardial infarction induction, and the Infarction group, which underwent a myocardial infarction induction with isoproterenol. The administrations for the infarction induction were performed during two consecutive days and a 24-hour interval between them. Twenty-four hours after the last administration, rats from both groups were anesthetized and sacrificed for blood sample collection to evaluate complete blood count (CBC) and biochemical parameters (SGOT, SGPT, troponin I, urea and creatinin), obtain myocardial fragments for oxidative stress markers analyses (catalase activity and glutathione concentrations) as well as histopathological examinations. RESULTS: There were no death cases in the Sham group, while the mortality rate in the Infarction group was 25%. Myocardial infarction induction with isoproterenol raised leukocytes and neutrophils counts, SGOT, troponin I and urea concentrations, reduced catalase enzyme activity and glutathione concentrations in the myocardium and let to histopathological concentrations as well. It did not exert alterations in terms of hemoglobin, SGPT and creatinin concentrations. CONCLUSIONS: The isoproterenol-induced myocardial infarction essay in rats was adequately reproduced in our laboratory, causing alterations in hematological, biochemical, oxidative stress markers and histopathological parameters.OBJECTIVE To evaluate and validate, in our laboratory, the essay of myocardial infarction induced by isoproterenol in rats by means of analysis of hematological, biochemical, oxidative stress markers and histopathological parameters. METHODS Thirty young, male, Wistar rats (145 to 230 g) were randomly allocated in two groups: Sham group, which underwent a virtual myocardial infarction induction, and the Infarction group, which underwent a myocardial infarction induction with isoproterenol. The administrations for the infarction induction were performed during two consecutive days and a 24-hour interval between them. Twenty-four hours after the last administration, rats from both groups were anesthetized and sacrificed for blood sample collection to evaluate complete blood count (CBC) and biochemical parameters (SGOT, SGPT, troponin I, urea and creatinin), obtain myocardial fragments for oxidative stress markers analyses (catalase activity and glutathione concentrations) as well as histopathological examinations. RESULTS There were no death cases in the Sham group, while the mortality rate in the Infarction group was 25%. Myocardial infarction induction with isoproterenol raised leukocytes and neutrophils counts, SGOT, troponin I and urea concentrations, reduced catalase enzyme activity and glutathione concentrations in the myocardium and let to histopathological concentrations as well. It did not exert alterations in terms of hemoglobin, SGPT and creatinin concentrations. CONCLUSIONS The isoproterenol-induced myocardial infarction essay in rats was adequately reproduced in our laboratory, causing alterations in hematological, biochemical, oxidative stress markers and histopathological parameters.

Myocardial revascularization surgery using composite Y-graft of the left internal thoracic artery: blood flow analysis

OBJECTIVE: To assess the left internal thoracic artery (LITA) flow pattern, when it was used to supply the left anterior descending artery (LADA) and another branch from the left coronary artery system (LCAS). METHODS: In the following study, the left internal thoracic artery flow was investigated by echocardiography Doppler, at rest and under dobutamine stress, in two twenty-patient groups. Group A consisted of patients who received only a pedicled LITA graft to the LADA. Group B consisted of patients who received a pedicled LITA graft associated with a vein graft to supply the LADA and another artery from the LCAS. The angiographic study showed graft patency in all patients from both groups. The following parameters were used: systolic flow (SF), diastolic flow, total flow, total flow in stress/total flow at rest ratio (TFS/TFR), systolic peak velocities (SPV), diastolic peak velocities and systolic peak velocity/diastolic peak velocity ratio. RESULTS: All analysed parameters were considered statistically significant, except SF, TFS/TFR and SPV. CONCLUSIONS: We concluded that in the same conditions and methodology, the LITA flow in the composite graft (group B) is higher than in the free graft (group A), which shows the great flow adaptability of LITA to respond to flow demand.

Vineberg's Procedure Modified Technique: Flow Analysis, Immediate Postoperative Results and Angiographic Evaluation

Abstract  Background: The purpose of this study was to evaluate angiographic results of patients subjected to a technique variation of Vinebergs procedure, as well as their morbidity and mortality in immediate postoperative period, and to analyze the flow of grafted left internal thoracic artery (LITA) at rest and under stress. Methods: Between September 1999 and April 2002 eight patients were operated upon, with implant of the internal thoracic artery (ITA) in the intimal layer of the left ventricle (LV) muscle. After 6 months, they underwent angiographic and Doppler evaluation. According to Doppler study of LITA, the sample was divided in two groups: “Vineberg group,” formed by eight patients; and “control group” consisting of 20 patients whose LITA directly revascularize the anterior interventricular artery (AIV). Angiography showed patency of all grafts in both groups. Blood flow and flow velocity in grafts were measured by Doppler echocardiography. T‐test for paired and unpaired samples were used for statistical analysis. Results: There were no deaths or complications in immediate postoperative period. Angiography showed 100% patency. The total flow (TF) of Vineberg group was 55% of the flow in the control group. In both groups, the TF increased with the stress. Conclusions: This Vinebergs technique modification can be successfully used in patients who cannot undergo traditional direct revascularization due to its low rates of morbidity and mortality and a high rate of patency, providing a significant blood flow both at rest and under stress.

A novel composite coronary bypass graft strategy using the saphenous vein bridge: could the venous valves induce worse patency results?

Jose Glauco Lobo Filho*, Heraldo G. Lobo Filho, Matheus D. Pimentel and Marilia L. Montenegro a Department of Surgery, Walter Cantidio University Hospital of the Federal University of Ceara, Fortaleza, Brazil b Department of Surgery, Federal University of Ceara, Fortaleza, Brazil c Federal University of Ceara, Fortaleza, Brazil d Christus College, Fortaleza, Brazil Received 7 May 2014; accepted 12 June 2014

Intraoperative Analysis of Flow Dynamics in Arteriovenous Composite Y Grafts

Objective Composite graft of left internal thoracic artery and great saphenous vein in revascularization of the left coronary system is a technique well described in literature. The aim of this study is to analyze blood flow dynamics in this configuration of composite graft especially in what concerns left internal thoracic arterys adaptability and influence of great saphenous vein segment on left internal thoracic arterys flow. Methods Revascularization of left coronary system with composite graft, with left internal thoracic artery revascularizing the anterior interventricular artery and a great saphenous vein segment, anastomosed to the left internal thoracic artery, revascularizing another branch of the left coronary system, was performed in 23 patients. Blood flow was evaluated by transit time flowmetry in all segments of the composite graft (left internal thoracic artery proximal segment, left internal thoracic artery distal segment and great saphenous vein segment). Measures were performed in baseline condition and after dobutamine-induced stress, without and with non-traumatic temporary clamping of the distal segments of the composite graft. Results Pharmacological stress resulted in increase of blood flow values in the analyzed segments (P<0.05). Non-traumatic temporary clamping of great saphenous vein segment did not result in statistically significant changes in the flow of left internal thoracic artery distal segment, both in baseline condition and under pharmacological stress. Similarly, non-traumatic temporary clamping of left internal thoracic artery distal segment did not result in statistically significant changes in great saphenous vein segment flow. Conclusion Composite grafts with left internal thoracic artery and great saphenous vein for revascularization of left coronary system, resulted in blood flow dynamics with physiological adaptability, both at rest and after pharmacological stress, according to demand. Presence of great saphenous vein segment did not alter physiological blood flow dynamics in distal segment of left internal thoracic artery.

Improvement of Mitral Regurgitation after Transapical Transcatheter Aortic Valve Bioprosthesis Implantation

Implantation of transcatheter aortic bioprosthesis has become a procedure with increasingly relevance in medical practice for the treatment of aortic stenosis, especially in patients with high or prohibitive surgical risk for traditional surgery. The presence of mitral regurgitation (MR) may be associated with increased morbidity and mortality, however, some studies have shown reduction in the degree of regurgitation of this valve after treatment of the aortic valve.

Doppler echocardiographic criteria in patency assessment of composite grafts from left internal thoracic artery

OBJECTIVES The purpose of our study was to establish, with an entirely noninvasive method, transthoracic Doppler echocardiography, criteria for patency of composite left internal thoracic artery grafts when placed on the left anterior descending artery and other branches of the left coronary system. METHODS The control group comprised 20 patients with single graft and 20 patients with composite graft; all forty having their patency confirmed by coronary angiogram (CA). In this control group, two Doppler echocardiographic variables, diastolic mean velocity-time and integral diastolic peak velocity to systolic peak velocity ratio were recorded. For each variable, established cut-off points were established, using the ROC (Receiver Operator Characteristic) curves, to identify criteria which could differentiate the composite grafts. Only patients with composite grafts were included in the 159-patients study group. The criteria established by the cut-off points in the control group were then applied to detect patency using a diastolic fraction of > 0.5 as the gold standard. The sensitivity, specificity, and positive and negative predictive values of these two criteria were determined. RESULTS In the control group, cut-off points of 0.71 and 0.09 m were established for the diastolic peak velocity/systolic peak velocity ratio and for diastolic mean velocity-time integral, respectively. In the study group phase, the sensitivity and negative predictive value of the diastolic peak velocity/systolic peak velocity > 0.71 criterion were 36% and 11%, respectively. Diastolic mean velocity-time integral > 0.09 m criterion, were 40% and 10.48%. The specificities and positive predictive values of each criterion were 100%. CONCLUSION Values reaching the criteria established for each variable indicate high probability of composite graft patency. Lower values have a large proportion of false negatives and are not conclusive as patency criteria.