Archivos del Instituto de Cardiologia de Mexico最新文献

Unlabelled: We examined the immediate and short-term outcomes after stenting protected and unprotected left main coronary artery (LMCA) stenoses, in patients with normal ventricular function. Left main coronary artery disease is regarded as an absolute contraindication for coronary angioplasty, because it has been associated with high procedural morbidity and poor mid-term results. Between february 1995 and february 1999, 596 procedures were performed in 468 patients. Ten patients who had disease involving the left main coronary artery were included. They were not candidates for coronary surgery. The post-stent antithrombotic regimens were aspirin and ticlopidine. The procedural success rate was 100% without episodes of subacute thrombosis. Three to six months follow-up angiography was performed in all, restenosis occurred only in two patients, there were two repeat PTCA (20%) and there were no deaths.

Conclusions: Stenting of unprotected and protected left main coronary artery stenoses may be a safe and effective alternative to surgery in carefully selected patients with normal left ventricular function. The results of our study suggests that when patients have prohibitive surgical risks, elective LMCA angioplasty and/or stenting maybe undertaken with a high procedural success rate as an effective alternative to CABG in carefully selected patients. Further studies in larger patient populations are needed to assess late outcome.

Unlabelled: Myocardial perfusion imaging is an useful procedure in the evaluation of patients with coronary artery disease, Gated SPECT technique evaluates simultaneously perfusion and ventricular function, left ventricular ejection fraction (LVEF), ventricular volumes and the transient ischemic dilatation of the left ventricle.

Objective: To evaluate the normal ventricle volumes and the ejection fraction of the LV obtained automatically with the Gated SPECT in Mexican population.

Methods: 100 patients were studied with low likelihood for CAD. All of them were studied with Tc-99m Sestamibi Gated SPECT. We obtained automatically the LVEF, and the end diastolic and systolic left ventricular volumes.

Results: Myocardial perfusion, regional motion and systolic thickening were normal in all patients. We obtained the mean values of EF and end diastolic and systolic volumes. These values were lower in female.

Conclusion: Tc-99m Sestamibi myocardial perfusion SPECT is an useful procedure, with high accuracy for the simultaneous evaluation of myocardial perfusion and ventricular function.

Incessant atrial tachycardia is an infrequent arrhythmia. Specially difficult to treat medically. Radiofrequency catheter ablation has been used successfully to cure a variety of supraventricular tachycardias. The purpose of this work is to report our initial experience in the treatment of atrial tachycardia. Ten patients, mean age 28.7 +/- 15 year with conventional drug-resistant symptomatic atrial tachycardia were treated with selective ablation of the focus using radiofrequency energy. It was found an abnormal automaticity in 10 tachycardias and in only one patient intra-atrial reentrant was supported. Radiofrequency energy was successful in 10 of 11 tachycardias with a mean of 9.3 +/- 6.8 applications using the technique of local atrial electrogram activation time with a mean value of -54 +/- -31 milliseconds at the successful ablation sites. No complications were observed and one patient had an early clinical recurrence. All patients with successful ablation are symptom-free, in sinus rhythm and without antiarrhythmic medications after 1 to 28 months of follow-up. Our initial experience support that radiofrequency catheter ablation is a safe and effective therapeutic option for incessant atrial tachycardia.

Unlabelled: The concept of the "jumping wave" phenomenon, i.e. of the slow and difficult passage of activation fronts from one septal mass to the other through an "intraseptal barrier", is derived from experimental studies of the Mexican School of Electrovectorcardiography.

Objective: To confirm the existence of histologically bipartite interventricular septum and of the electric independence of both septal masses.

Methodology: We examined the histological characteristics of both septal masses in rat, canine, and human hearts. We also analyzed the morphological and chronological data of intracavitary records in the presence of different degree proximal blocks, comparing these findings with those obtained when peripheral blocks existed.

Results: We found a medial, longitudinal band between the two septal masses in animal as well as in human hearts. The analysis of intracavitary electric records confirmed a slow and difficult transmission of the activation fronts from one septal mass to the other, in the presence of proximal blocks and ventricular arrhythmias. Morphological and chronological changes of intraventricular complexes could not be explained if the septal activation process were of syncytial type.

Conclusions: Results of this study firmly support the validity of our approach to the septal activation process in the presence of ventricular conduction disorders and arrhythmias. This approach helps to detect the possible coexistence of dead septal tissue.

In 1994, the United States Agency for Health Care Policy and Research issued clinical practice guidelines for the diagnosis and management of unstable angina and non-Q-wave myocardial infarction. In the past 5 years, rapid progress has been made in the management of patients with unstable coronary syndromes, and treatment guidelines should be revised to reflect these advances. An international forum of cardiology investigators convened to discuss areas in which the diagnosis and treatment of unstable angina/non-Q-wave myocardial infarction should be modified. Although there were areas of controversy, it was agreed that there is sufficient evidence to recommend the following changes: 1) the use of serum cardiac markers should be expanded to include troponin I and T levels as diagnostic and prognostic tools, 2) low-molecular-weight heparins should replace UH as antithrombin agents, 3) new classes of antiplatelet agents are recommended in addition to aspirin, 4) the use of cholesterol-lowering drugs is appropriate in the long-term management of these patients. The rationale for these suggested revisions, including evidence from pertinent clinical trials, is discussed in detail in the accompanying document.

In order to offer a pathogenetic explanation for the absence of atrioventricular connexion, a correlation was made between the pathologic anatomy of this cardiac malformation and the embryonic processes which take part in the septation of the atrioventricular canal and the development of atrioventricular connections. The correspondence was made between the development of the canal's atrioventricular cushions, the septation of the common atrioventricular canal, the right and left atrioventricular canals and the morphogenesis of the mitral valve, all these processes were correlated with the anatomic elements derived from them. This led to infer that the malposition of the atrioventricular cushions divide the common atrioventricular canal unequally, giving rise to a narrow canal becoming atretic and a big canal where the mitral valve is evolved. The extreme lateralization of the atrioventricular septum to the right side would led to the absence of the right atrioventricular connection and the same process but to the left side, would give rise to the left absence of the atrioventricular connection. This ectopic septation process is supported by similar ones which can occur in other segments of the heart such as in tetralogy of Fallot and the transposition of the great arteries. This hypothesis explains sufficiently the pathologic anatomy of this type of congenital heart disease.

Unlabelled: In order to evaluate our experience in heterotopic cardiac transplantation, we conducted a retrospective analysis of the clinical files of patients who underwent this procedure.

Results: A total of 405 heart transplants were performed in our institution. In 24 (5.9%), the grafts were placed heterotopically. In group I (12 patients), the indication was irreversible pulmonary hypertension and in group II (remaining 12 patients), it was marginal grafts or size mismatch. Both groups demonstrated similar demographics and the survival rate was slightly better in group I. Nine patients from group I demonstrated an early reduction in pulmonary pressures which normalized in one year.

Conclusions: The heterotopic heart supports the function of the native ventricles. In 9 patients, the heterotopic heart enables the reversal of a state of pulmonary hypertension previously thought to be irreversible. This finding supports the use of pulmonary vaso-dilators on a chronic basis or the use of a left ventricular assist device pre-transplant with the intention of normalizing pulmonary pressures and allowing the patients to become candidates for orthotopic cardiac transplantation and thereby avoiding the necessity of heterotopic cardiac transplantation.