Volume 17 - Número 3

Keywords:

INTRODUCTION: Hypomagnesemia and ischemia followed by reperfusion often occur in cardiac surgery. Both of them are associated with endothelial dysfunction which interfers negatively with patient evolution. Phisiopatology of these disturbances is similar and involves G-proteins dysfunction. OBJECTIVE: The present study focuses on the endothelial dysfunction consequent to the lesion resulting from global ischemia followed by reperfusion and the potential protective influence of magnesium on the endothelium functional integrity in isolated coronaries of dogs. METHOD: Segments of canine coronary arteries were suspended in organ chambers to measure isometric force. Endothelial dysfunction was evaluated by the ability of these segments to produce nitric oxide changing the initial isometric force. Four groups with six dogs in each one were selected: SEM CEC (control), CEC (110 minutes of perfusion without ischemia), ISQ (45 minutes of ischemia), ISQ/REP (45 minutes of ischemia followed by 60 minutes of reperfusion). The magnesium action was evaluated in three different phases: I (organ chambers with magnesium), II (organ chambers without magnesium) and III (organ chambers with restored magnesium). Three pharmacological agonists were used which represented the main steps involved in the nitric oxide production: the membrane receptor of the endothelial cell – acetylcholine (ACh); transduction of the signal between the receptor and the intracellular processes through the G-protein – sodium fluoride (NaF); liberation of intracellular stocks of calcium – calcium ionophore (A23187). The study of endothelial function was combined with the evaluation of smooth muscle activity dependent on GMPc – sodium nitroprusside (NPS). RESULTS: The major findings of this investigation were as follows: 1) presence of magnesium in priming seemed to attenuate the endothelial dysfunction caused by global ischemia followed by reperfusion; 2) presence of magnesium in the organ chamber (phase I) was associated with the greatest relaxation in response to agonists of the nitric oxide production; 3) removal of magnesium in the organ chamber (phase II) was linked to the reduction in the relaxation intensity in response to agonists of the nitric oxide production; 4) the magnesium restoration to the organ chamber (phase III) allowed restoration of the relaxation observed in the phase I, only in response to the direct stimulation of the G-proteins. For the rest of the remaining agonists, the restoration was associated with the additional reduction in the relaxation intensity; 5) the smooth muscle received the influence of the magnesium concentration in the organ chamber. CONCLUSION: It was concluded that magnesium favorably influences the nitric oxide production by the coronary endothelium attenuating the endothelial dysfunction caused by global ischemia followed by reperfusion. Keywords: Magnesium; Endothelium; Ischemia; Coronary Reperfusion

OBJETIVE: Establishment of cardiopulmonary bypass using the right subclavian artery with a supraclavicular approach. METHOd: Between october 2001and march 2002, 4 patients were operated with the diagnosis of Stanford type A aortic dissection. The supraclavicular approach to the right subclavian artery was used for establishment of cardiopulmonary bypass in all of them. RESULTS: The right subclavian artery was canulated directly, without interposition of grafts. There was no neurovascular complication related to the procedure nor wound site complications. The hospital mortality was 25%. The death was not procedure related. CONCLUSION: The supraclavicular approach to the subclavian artery allows a good exposition of this artery in a region where it has enough size for direct canulation and establishment of cardiopulmonary bypass, with satisfactory canula position. Keywords: Aorta, pathology; Aorta, surgery; Aneurysm dissecting, surgery; Extracorporeal circulation

INTRODUCTION: Cardiopulmonary bypass (CPB) and Ascending Aorta manipulation (AAM) are associated with a high incidence of stroke in coronary surgery in patients older than 75 years. This complication is due, mostly, to the handling of the aorta by the time of the cross-clamping, either for heart isolation from CPB, or to perform saphenous vein graft anastomosis to the ascending Aorta. OBJECTIVES: To observe immediate and mid-term mortalities and occurrence of stroke in the immediate post-operative period in patients older than 75 years who underwent surgical revascularization of the Left Coronary Artery System (LCAS) without CPB and without AAM. METHOD: Between January 2000 and April 2002, 40 patients, with ages ranging from 75 to 89 years (average 79.1), underwent surgical revascularization of the LCAS, with Left internal mammary artery (LIMA) graft to the Left Anterior Descending artery (LAD), and with Saphenous Vein Graft (SVG) originated from LIMA to one or more left coronary artery branches (composite graft), without CPB and without AAM. Male gender was predominant (67.5%). Eighty-nine arterial grafts were performed, with average of 2.22 per patient, of which 40 (44.94%) of LIMA and 49 (55.06%) of saphenous vein. The occurrence of stroke was evaluated by neurological and clinical exams. RESULT: It was not observed stroke or deaths in the immediate post-operative period. CONCLUSION: Surgical revascularization of the LCAS in patients older than 75 years without CPB and without AAM can be performed systematically in order to avoid occurrence of stroke, and so, reducing the mortality of the procedure. Keywords: Myocardial revascularization, mortality; Myocardial revascularization, adverse effects; Myocardial revascularization, methods; Cardiopulmonary bypass, adverse effects

OBJECTIVE: The purpose of this research is to evaluate the efficacy of the lidocaine in myocardial protection with normothermic antegrade blood cardioplegia. METHOD: Twenty six dogs were studied divided at random into two groups of ten and one group of six, depending on which cardioplegic solution they had received. Group I received a cardioplegic solution induction of lidocaine 5mg/ kg, 41,6mEq/l of KCl and 180ml of normothermic blood. Group II received the same solution except for the lidocaine and group III received only 180ml of blood. Every 20min 120ml of normothermic blood was reinfused. All dogs underwent cardiopulmonary bypass, two hours of myocardial ischemia and three hours of reperfusion. These dogs were evaluated through operative mortality, myocardial enzymes such as cardiac troponin I and creatine kinase, lactate production, hemodynamic performance measured by ejection fraction and cardiac output, and morphometrics mitochondrial ultrastructural changes. Statistical analysis tests used to compare the results were the Fisher exact test and the twoway Anova. RESULTS: The results have shown that the animals from group I in comparison to those of group II, had no mortality (p=0,08), a lower production of creatine kinase (p<0,05), lower mitochondrial ultrastructural changes (p=0,036) and had no difference with cardiac troponin I production, lactate production and hemodynamic performance. CONCLUSIONS: In conclusion it can be said that lidocaine offered an additional protection to the ischemic myocardial during cardiopulmonary bypass and that animals from groups I and II, with time, showed significant changes, compatible with cellular damage, for all the subjects evaluated. Keywords: Myocardial protection; Cardioplegic solution; Lidocaine

PURPOSE: To present a literature review and critical analysis about the inhaled nitric oxide (NO) application in heart surgery. METHOD: metaanalysis of published papers indexed in the MEDLINE database of the United States National Library of Medicine. Points emphasized were: the NO biology, mechanism and selective site of the inhaled NO, technical and ethical aspects, clinical applications in heart surgery. Also, a critical analysis, attempt to demonstrate the current concepts about the inhaled NO therapeutical applications RESULT: The main evidences were: the) Inhaled NO is presently recognized as a valuable pharmacological tool in the milieu of the neonatal and pediatric intensive medicine and cardiothoracic surgery; b) Other adult applications, as obstructive lung disease and acute respiratory distress syndrome, need careful observations; c) The inhaled NO therapeutics is relatively inexpensive, but it is important to consider that it should not be used in all patients, based on paradigms of efficiency and potential toxicity; d) The recent discoveries of their anti-inflammatory effects and non pulmonary effects open new horizons for future applications. CONCLUSION: Although it is evident the extreme variability of the inhaled NO pulmonary vasodilatatory selective effect, medical centers that treat patients with cardiopulmonary diseases, mainly associate to pulmonary hypertension, owe disposal of this therapeutic resource. In the absence of trials involving great number of patients, and, in spite of its potential toxicity, the inhaled NO therapeutics have to be used under rigid technical protocols to save lives. Keywords: Nitric oxide, therapeutic use; Pulmonary hypertension; Cardiac surgical procedures

OBJECTIVE: This study reviews our experience with the use of nitric oxide inhalation (NOi) in the treatment of the refractory pulmonary hypertensive crisis (PHC) during the immediate post-operative period (IPOP) of heart transplantation (HT). METHOD: Between Oct/97 and Feb/02, 31 HT in adults were performed. Among them were patients with Pulmonary Vascular Resistance (PVR) greater than 6 uW, or patients with PVR greater than 2,5 uW during the pharmacological test. All patients were weaned from the CPB (M=101±21 minutes) in use of dobutamine, dopamine and milrinone. In the absence of an adequate response to these drugs and with the evidence of PHC, NOi was given, beginning with 20ppm and increasing, when necessary, up to 40ppm. The recording of the left atrium and pulmonary artery pressures, serial arterial blood gases samples and trans-thoracic echocardiograms (TTE) were performed. The donor's brain death (BD) time mean was 16±5,1 hours. RESULTS: In five patients (1 female) (mean age = 42 years) NOi was employed, due to low cardiac output signs and evidence of PHC and right ventricular dysfunction. The mean CPB time was 150,8±34,3 min. The pre-NOi mean PAP was 87 mmHg (range 75-115), and the mean arterial PO2 = 60mmHg (FiO2=100%). The TTE showed moderate-severe dilation of the right ventricle. NOi was given during a mean of 35h (range 6 to 96), being weaned only after hemodynamic stability was achieved. There was only one early death, at the 17th post op. day due to sepsis. All the remaining patients are in NYHA class I. CONCLUSIONS: The prolonged CPB time (> 120 min) and the time of brain death of the donor are factors that increase the risk of PHC. The NOi is a useful tool in dealing with this complication when there is an inadequate response to the conventional treatment. Keywords: Nitric oxide, therapeutic use; Heart transplantation; Right ventricular dysfunction; Pulmonary hypertension

OBJECTIVE: Analyse the risk factors for hospital mortality in valvar reoperations. METHOD: A prospective analysis was performed of 194 patients that underwent valvar reoperations between July 1995 and June 1999. The following variables were analysed: sex, age, functional class, number and type of previous operations, cardiac rhythm, urgency at operation, creatinin level, left ventricular ejection fraction, left ventricular systolic and diastolic diameters, right ventricular systolic pressure, prothrombin activity, activated partial thromboplastin time relation, platelets count, extracorporeal circulation time, aortic cross-clamp time, number and position of valves, type of procedure, associated procedures and intraoperative bleeding volume. Univariate and multivariate statistical analysis was performed to determine the risk factors for hospital mortality. RESULTS: The overall hospital mortality was 8,8% (17 patients). Univariate analysis showed that the following variables were associated with higher mortality rates: advanced New York Heart Association functional class, decreased left ventricular ejection fraction, decreased prothrombin activity, increased creatinine level, longer aortic cross-clamp time, prolonged extracorporeal circulation time, concomitant associated procedures, and higher intraoperative bleeding volume. Logistic multivariate analysis identified advanced New York Heart Association functional class, creatinine level higher than 1,5 mg/dl, and extracorporeal circulation time longer than 120 minutes as independent predictors of hospital mortality. CONCLUSIONS: The variables functional class IV, creatinin level > 1,5 mg/dl and extracorporeal circulation time > 120 min were independent predictors of hospital mortality in valvar reoperations. Keywords: Heart valves, surgery; Risk factors

METHODS: From August 1997 to May 2001, off-pump coronary artery bypass grafting (OPCAB) was performed in 250 consecutive patients with multivessel disease. Ages ranged from 38 to 83 years (mean-age 59.9 years) and 62% of the patients were males. The main surgical indication was chronic coronary insufficiency (82%). The surgical approach was through median sternotomy in all patients. RESULTS: Three (1.2%) patients needed cardiopulmonary bypass support. In the 247 remaining patients, we performed 592 grafts (mean 2.4 grafts/patient). The left internal thoracic artery was used in 198 (80.1%) patients, the right internal thoracic artery in 5 (2%) patients and the saphenous vein in all patients (100%). The most frequently revascularized coronary arteries were the anterior interventricular branch (89%) and the obtuse marginal (53%). The mortality rate was 4% and the main primary cause of death was myocardial infarction (1.2%). Twenty-three (9.3%) patients had major complications in the postoperative period. The mean hospital stay was 7.7 days. CONCLUSION: In conclusion, OPCAB can be safely performed in patients with multivessel disease, with low rates of postoperative complications. Keywords: myocardial revascularization, surgery; Myocardial Ischemia, surgery; Extracorporeal circulation

OBJECTIVE: Dual chamber pacing has been recognized as an complementary therapy to reduce left ventricular outflow tract gradient (LVTOG) in patients with hypertrophic obstructive cardiomyopathy (HOCM). Although controversies still remains, most reports show the effectiveness of this novel method to reduce LVOTG, improved clinical status and increase survival in patients with HOCM refractary to clinical treatment. The aim of this study is to present the results of DDD pacemaker therapy in a group of patients with HOCM unresponsive to pharmacological management. METHOD: Forty-two patients with HOCM refractory to medical treatment and with an increasing or higher than 50 mmHg LVOTG were implanted a transvenous DDD pacemaker. The optimal atrioventricular interval was defined as that producing the lowest left ventricular outflow tract gradient without compromise of aortic or left atrial pressures. After implantation, the pacemaker was programmed with a pulse rate capable of controlling the atria and the ventricle with a reduced atrioventricular interval (equal or lower than 120 ms). Pacemaker programming was performed during ECHO evaluation to obtain the lowest LVOTG. RESULTS: The majority of patients showed hemodynamic improvement during permanent pacing. Initial pacemaker programming resulted in a reduction of the LVOTG from the mean control value of 96.50±30.55 mmHg to 41.80±22.84 mmHg (p<0,001), and in the last follow-up LVTOG decreased even further to 30.00±23.03. CONCLUSION: Dual-chamber pacing improve subjective measures of functional status in patients with symptomatic HOCM in this study, offering reduction in LVOTG and improvements in objective measures of patient symptoms and functional status. Keywords: Hypertrophic obstructive cardiomyopathy; Pacemaker, treatment

OBJECTIVE: To study the variations of the atrial natriuretic peptide (ANP) introduced by extracorporeal circulation (ECC) during cardiac surgery, and to test the hypothesis that there is a correlation between the ANP plasma levels, right atrial pressure (RAP), left atrial pressure (LAP), diuresis and natriuresis. METHOD: Study of a cohort of 15 patients submitted to myocardial revascularization using ECC. The intervals of the observation times were: t0= 10 minutes before ECC (control value); t1= 10 minutes after total flow in ECC; t2=30 minutes into total flow in ECC; t3= end stage of ECC at a nasopharingeal temperature of 36º C; and t4= 30 minutes after ECC has ended. RESULTS: The ANP, LAP and RAP values varied significantly (p<0.001). The ANP dropped from t0 to t1 (NS), and then rose progressively until t4(p<0.001). The LAP and RAP were reduced (p <0.001) between t0 and t1, rising progressively until t4 (p<0.001). The urinary Na+ rose between t0 and t3 (p<0.001) with a drop at t4. The diuresis increased progressively at all times considered (p<0.001). A significant correlation was found between ANP and the diuresis volume at t0, correlation coefficient of 0.535 (p=0.040) and at the time equal to t2 between ANP and RAP, a correlation coefficient of 0.590 (p=0.021). CONCLUSION: The ANP concentrations present variations during revascularization surgery with ECC, favoring the idea that they are related to atrial pressures and, at the end of ECC, they have an important function in sodium excretion and the volume of diuresis. Keywords: Atrial natriuretic factor; Extracorporeal circulation; Cardiac surgery

INTRODUCTION: Mediastinitis is a rare though potentially fatal complication. The incidence is reported to be between 0.2% and 5.0% and is a major cause of postoperative morbidity. Despite early diagnosis and proper treatment, prognosis is poor because of the chance of mediastinal spread of the infection and poor physical state of these patients. OBJECTIVE: To review the casuistic of mediastinites. METHOD: The records of all 2,272 patients who underwent cardiac surgical procedures between 1991 and 2000 were reviewed. All operations were performed using longitudinal sternotomy and extracorporeal circulation in João XXIII Hospital / Institute of Cardiovascular Surgery of Paraíba in Campina Grande, Paraíba. RESULTS: The complication occurred within, on average, 10 days after operation. In total of 37 (1.6%), 8 (21.6%) deaths occurred. Mediastinitis were reported in 19 (51.4%) cases, in patients submitted to coronary artery bypass grafting, 13 (35.1%) in valve diseases, 4 (10.8%) in congenital cardiopathy corrections and 1 (2.7%) in ascending aortic aneurysm. Several risk factors mediastinitis were identified (obesity, prolonged stay in hospital, diabetes mellitus, smoking, reoperation and emergency surgery), especially the prolonged stay in intensive-care unit for more then 72 hours before cardiac operation. Bacterial cultures of exudates were positive in 35 (94.6%) of 37 patients; Staphylococcus aureus was the responsible pathogen in 17 (48.6%) patients. CONCLUSION: The incidence of mediastinitis after longitudinal sternotomy following cardiac surgery do not decreased in the last 10 years and represents a surgical challenge, in spite of the progress added to the diagnostic and therapeutic of this pathology. Keywords: Mediastinitis; Mediastinal infection; Cardiac surgery, infection; Surgical infection

Coronary arteries fistulas have low incidence on the congenital heart defects, many times they are assymptomatic, and have to be suspected when continuous cardiac murmur is present. The symptoms can be precordial pain or cardiac failure and they must be studied correctly to a save surgical management or clinic treatment. In this paper are related three cases surgically treated with good results and literature review. Keywords: Coronary arteriovenous fistula; Coronary chamber communications; Anomaly coronary artery