Paulo Moreno

Técnica cirúrgica simplificada pode ser eficaz no tratamento da fibrilação atrial crônica secundária a lesão valvar mitral

INTRODUCTION: Atrial fibrillation, nowadays, has been treated surgically by the maze procedure and its modifications. However, there is some evidence that points to the pulmonary vein ostia as trigger point for this arrhythmia. We postulate a surgical approach of pulmonary vein isolation or left atrial isolation in order to treat this disease. In this study we show the initial results of this technique in patients with chronic atrial fibrillation associated with mitral valve disease. MATERIAL AND METHODS: Seven patients were operated on by pulmonary vein isolation (IVP) and compared to the past results of the 57 patients in which the maze procedure had been done (Cox 3). RESULTS: Age - 49±8 years vs. 49±11 years (IVP vs. Cox 3), 71% and 72% (IVP vs. Cox 3) were female. Left atrium size was 5.5±0.7 cm vs. 6.0±1.1 cm (IVP vs. Cox 3). Ventricular EF 63±10% vs. 64±6% (IVP vs. Cox 3). Extracorporeal circulation time 91±33 min vs.104±29 min (IVP vs. Cox 3). Aortic cross-clamping 71±23 min vs. 83±26 min (IVP vs. Cox 3). Cardiac rhythm: sinusal / atrial n(%): 6(86) vs. 46(80) (IVP vs. Cox 3). Cardiac pace rhythm n(%):1 (14) vs. 4 (7) (IVP vs. Cox 3). Atrial fibrillation n(%):0 vs. 7 (13) (IVP vs. Cox 3). CONCLUSIONS: The initial results show sinus rhythm restoration and its maintenance. We have already started a double-blind randomized trial between these two surgical techniques.

Results of the surgical treatment of chronic atrial fibrillation

OBJECTIVE Report clinical experience in surgical treatment of atrial fibrillation (AF) by Cox-maze procedure. METHODS 61 patients underwent surgical treatment for AF. Two had primary AF and 59 AF secondary to heart disease (2 atrial septal defects, 57 mitral). Ages ranged from 20 to 74 years (mean = 49). There were 44 females (72%). The surgical technique employed was Cox 3 without cryoablation. The patients were follow-up in specific at patient clinics and underwent periodical ECG, exercise tests, echocardiogram and Holter monitoring. RESULTS In-hospital mortality was 4.9% and late mortality 1.6%. A temporary pacemaker was used in 28 (46%) and a definitive in 7 patients (11.4%). On hospital discharge, AF remained in 17%; 63.9% had sinus rhythm, 6.9% atrial rhythm, 1.7% junctional rhythm, and 10.3% had pacemaker rhythm. In the last evaluation, AF was present in 19.5%; (70.5% sinus rhythm, 4% atrial rhythm, 2% atrial tachycardia, and 4% pacemaker rhythm). There was no report of thromboembolic episodes. Chronotropic response was considered adequate in 19%, intermediate in 29%, and inadequate in 42%. In Holter monitoring, the mean heart rate was 82 +/- 8 bpm, with a minimum of 57 +/- 7 bpm and maximum of 126 +/- 23 bpm, with supraventricular extrasystoles in 2.3 +/- 5.5% of the total heartbeats and ventricular extrasystoles in 0.8 +/- 0.5%. In the echocardiogram, the A wave was present in the left atrium in 87.5%. CONCLUSION Maze procedure is effective and has acceptable surgical risk. Atrial or sinus rhythms remain stable with a small but remarkable frequency of atrial and ventricular arrhythmias. Left atrial contraction is present, although attenuated, as well as the chronotropic response to exercise.

Gene therapy with VEGF 165 for angiogenesis in experimental acute myocardial infarction

OBJECTIVE: Evaluate coronary angiogenic response to transmural injection of plasmid encoding VEGF 165 in acute myocardial infarction (AMI) zones in a canine model. METHODS: The heart of eleven dogs was exposed and AMI was induced by occlusion of the diagonal branch of anterior descending coronary artery. For each of 10 selected points in the infarction area and its peripheral zone injections of 1 ml of saline solution (control group: five dogs) or 1 ml of plasmid encoding VEGF 165 solution (200 µg/ml) (VEGF group: six dogs) were introduced. Tecnecium myocardial scintigraphy was performed immediately after animal recovery and 14 days later to evaluate the myocardial perfusion. The animals were sacrificed and the hearts were submitted to a histological study of the infarcted area, peripheral zone and normal posterior ventricular wall, to evaluate the number of arterioles and capillaries. RESULTS: Immediate modifications in myocardial perfusion found in scintigraphic studies were similar in both groups. In the second evaluation at 14 days, hypoperfusion of ischemic area had recovered by 70% to 90% when compared to the day of AMI. Histologic evaluation of the peripheral area of AMI indicated a larger number of vessels in the VEGF group when compared to controls (mean: 123.81 + 21.48 and 40 + 6.13, p < 0.01, respectively). This increase resulted mainly from an increase in the number of capillaries (97.5 + 16.04 in the VEGF group and 22.18 + 3,25 in control group, p < 0.01), as the number of arterioles did not increase significantly. In the VEGF group, a comparison in the number of vessels of the AMI peripheral area and normal myocardium revealed a non-significant increase of vessels in the ischemic area (123.81 + 21.48 and 95.14 + 41.19). CONCLUSION: An intramural injection of plasmid VEGF 165 resulted in a significant increase in the number of capillaries in the peripheral AMI area. This increase may have a beneficial effect in the reduction and recovery of the ischemic area secondary to AMI.

Experimental model of gene transfection in healthy canine myocardium. Perspectives of gene therapy for ischemic heart disease

OBJECTIVE To assess the transfection of the gene that encodes green fluorescent protein (GFP) through direct intramyocardial injection. METHODS The pREGFP plasmid vector was used. The EGFP gene was inserted downstream from the constitutive promoter of the Rous sarcoma virus. Five male dogs were used (mean weight 13.5 kg), in which 0.5 mL of saline solution (n=1) or 0.5 mL of plasmid solution containing 0.5 micro g of pREGFP/dog (n=4) were injected into the myocardium of the left ventricular lateral wall. The dogs were euthanized 1 week later, and cardiac biopsies were obtained. RESULTS Fluorescence microscopy showed differences between the cells transfected and not transfected with pREGFP plasmid. Mild fluorescence was observed in the cardiac fibers that received saline solution; however, the myocardial cells transfected with pREGFP had overt EGFP expression. CONCLUSION Transfection with the EGFP gene in healthy canine myocardium was effective. The reproduction of this efficacy using vascular endothelial growth factor (VEGF) instead of EGFP aims at developing gene therapy for ischemic heart disease.

Assessment of Thromboembolism After the Cox-Maze Procedure for Chronic Atrial Fibrillation Secondary to Mitral Valve Lesion

OBJECTIVE To assess the occurrence of late thromboembolism after surgical repair of chronic atrial fibrillation (AF) simultaneously with repair of mitral valve using the Cox-Maze procedure. METHODS 69 patients underwent Cox 3 procedure, with no cryoablation simultaneously with mitral valvuloplasty or prosthesis. Mean age was 49.9+/-13.2 years. Mean follow-up was of 31.7+/-19 months. Types of lesion were as follows: 33 (48%) stenoses, 23 (33%) insufficiencies, and 13 (19%) double lesions. Procedures were: 64 (93%) valvuloplasties, 3 (4%) biological and 2 (3%) mechanical prosthesis placement. There were 9 (13%) patients with previous systemic embolism and 2 (3%) had left atrial thrombi. RESULTS Early mortality was 7% and late 1%. 2 patients (3%) were reoperated for mitral placement. At last evaluation, 10 patients (15%), were in AF. The remaining 59 (85%) were either in sinus / atrial rythm (74%) or under pacing (12%). There were no occurrence of early or late, systemic or pulmonary embolism. Permanent anticoagulation was employed in 16 cases, 10 in regular rythm and 6 in AF. The remaining 47 (75%), 2 in AF and 45 in regular rythm, did not receive anticoagulants. CONCLUSIONS These results are in accordance with others series, where the occurrence of embolism was rare after maze procedure. Permanent systemic anticoagulation seems to be unnecessary in those cases.

Análise comparativa dos resultados da cirurgia do labirinto (Cox-maze) para fibrilação atrial crônica em pacientes com doença valvar mitral reumática ou degenerativa

The results of maze procedure in rheumatic mitral valve disease are subject to debate. This paper reports medium term results in rheumatic and degenerative mitral valve surgery associated with maze procedure. From 1994 to 1997, 57 patients were operated on. They were divided into two Groups; R (rheumatic) 40 patients and D (degenerative) 17. Group R included 8 (20%) males and 32 (80%) females. Group D: 8 (47%) males and 9 (53%) females (NS). Age in R = 47 ± 11 and D 54 ± 17 years (p < 0.05). Left atrial size was 6.1 ± 1.1 cm in R and 5.9 ± 1.2 in D (NS). There were 3 hospital deaths, 1 (2.5%) in R and 2 (12%) in D. One D patient (7%) died late. Pacemakers were implanted in 4 (10%) R and 2 (17%) in D (NS). There were no significant differences regarding surgical duration of perfusion or myocardial ischemia, antiarrhythmic medications, immediate or late cardiac rythms and occurrence of arrythmias. Ergometric evaluation for measuring chronotropic response revealed a normal response in 6 (25%) R and 1 (10%) in D at a mean of 16.6 months PO. In the lower response group, 3 (12.5%) R and 6 (60%) D had intermediate values (p = 0.009) and 15 (62.5%) R versus 3 (30%) D had values below 75% of expected heart rate (p = 0.09). Rheumatic or degenerative ethiology of mitral valve disease does not influence the results of maze procedure in this patient population. Mean chronotropic response to exercise tends to be lower in degenerative patients.

Biópsia endomiocárdica prediz a recuperação da função ventricular após cirurgia de revascularização do miocárdio

OBJECTIVE Patients with ischemic heart failure may benefit from coronary artery bypass grafting. The histopathological variables associated with improvement in ejection fraction 6 months after surgery were assessed. METHODS This study comprised 24 patients indicated for coronary artery bypass grafting, ejection fraction < 35%, functional class II-IV heart failure, and mean age 59 +/- 9 years. Endomyocardial biopsies were performed during and 6 months after surgery. Extension of the fibrosis, number of cells with myocytolysis, and hypertrophy of the muscle fiber were quantified by using a system of image analysis. Clinical and functional review was repeated within 6 months. RESULTS A significant improvement in heart failure functional class was observed in 16 patients after 6 months of follow-up (from NYHA functional class 2.8 +/- 0.7 to 1.7 +/- 0.6; P < 0.001), but the ejection fraction did not change (25 +/- 6 % vs. 26 +/- 10%). Hypertrophy of the muscle fiber was similar in the specimens biopsied in the pre- and postoperative periods (21 +/- 4 vs. 22 +/- 4 microm), but the extension of fibrosis (8 +/- 8 vs. 21 +/- 15% area) and the number of cells with myocytolysis (9 +/- 11 vs. 21 +/- 15% cell) significantly increased. However, the composition of a histological score combining those 3 variables indicated a greater increase in the ventricular function of those with a lower degree of preoperative histopathological alterations. CONCLUSION Patients with ischemic cardiomyopathy undergoing coronary artery bypass grafting improved their ventricular function when the preoperative adverse histopathological alterations were of a lower degree.