Archivos del Instituto de Cardiologia de Mexico最新文献

Several reports have demonstrated that radiofrequency catheter ablation provides effective control of a variety of supraventricular and ventricular tachycardias. This report details the results of radiofrequency catheter ablation in 1500 consecutive patients with a wide variety of supraventricular and ventricular tachycardias treated in the Instituto Nacional de Cardiología "Ignacio Chavez", between April 22, 1992 until December of 1999. Tachycardias were associated with the presence of an accessory pathway in 987 patients (65.8%). Dual accessory pathways were present in 24 patients giving a total of 1,012 accessory pathways. The mechanism of the arrhythmia was atrioventricular nodal reentrant tachycardia in 321 patients (21.4%). Ablation of the reentrant circuit of atrial flutter within the right atrium was attempted in 109 (7.2%) patients and a primary atrial tachycardia in 13 patients (0.8%). Atrioventricular node ablation and permanent pacemaker implantation were performed in 26 patients (1.7%). Finally we performed radiofrequency catheter ablation in 37 (2.4%) patients with ventricular tachycardia. Radiofrequency catheter ablation was successful in 908 of 1012 (89.7%) patients with accessory pathways with a complication rate of 10 (0.98%) and a recurrence rate of 92 (9%). AV nodal reentry was successfully abolished in 319 of 321 patients by selective ablation of the slow pathway in 297/321 (92.5%) patients and the fast pathway in 22/24 (92%) patients. The complication rate of this group was 8/321 (2.4%) with a recurrence rate of 34 patients (10.5%). The reentrant circuit of atrial flutter was ablated successfully in 86 of 109 (76.8%) patients with a recurrence flutter in 14 (12.8%) patients. Five of 13 (38.4%) cases of primary atrial tachycardia were successfully ablated. Complete AV block was achieved in 26 of 26 (100%) patients with atrial fibrillation or flutter treated by AV nodal ablation. The procedure was successful in 28 of 37 (75.6%) patients with fascicular ventricular tachycardia. The results of this series of patients demonstrates the safety and efficacy of radiofrequency ablation for the treatment of a wide variety of taquicardias with high rate of success 1375 of 1500 patients (91.6%), with 142 recurrences (9.4%), 15 complications (1%), and no mortality.

Infective endocarditis is a frequent complication in intravenous drugs abusers. It is evident that in recent years this problem has increases as a consequence of the growing number of drug addicts. We review the clinical files of patients who entered the Regional General Hospital No. 20 IMSS in the City of Tijuana Mexico between May 1994 and May 1998 with diagnosis of infective endocarditis and had evidence intravenous abuse. Eight patients were included in the study. None of them had preexisting valve abnormalities. The infection involved right-sided values in 62.5% of cases left-sided values in 12.5%, and both sides in 12.5% of cases Staphylococcus aureus was the infecting germ in 50% of the cases. Survival of patients with right infective endocarditis was 75% and only 25% of them required surgical intervention. The mortality of infection in left side was 75% and 100% if infection involved both sides. Infective endocarditis in drugs abusers has a favorable prognosis when right sided valves are affected. Mortality rates are higher in patients with left-sided involvement.

Simultaneous right and left ventricular function curves (VFC, R, L) were obtained in a canine model, (open chest preparation), with and without pericardium. Preload and afterload conditions for the right and left ventricles were controlled. VFC were constructed from zero to 25 mmHg of ventricular end-diastolic pressures and by increasing the cardiac output from 50 to 250 mL/kg-1min-1. Both, right and left VFC showed an initial steep rise at low filling pressures and then flattened off to a plateau at high filling pressures. The best mathematical model that fitted with the VFC, with and without the pericardium was the parabola (r2 = 0.71, 0.72 respectively). After pericardiectomy R and L VFC were displaced to the left of the VFC with pericardium and a decrease in filling pressures were noted at the same points of cardiac output, findings that suggest a restraining effect of the pericardium. By subtracting the filling pressures obtained with pericardium from those without pericardium at the same levels of cardiac output, pericardial pressures were derived. In all the range of the VFC the pericardial pressures were positive, and this pressure increase as cardiac output increase. Thus the transmural pressure was never cero, for both right and left ventricles. The observed relation for the R and L filling pressures, derived from a polynomial equation of second order suggest a small although not unimportant effect of the pericardium at normal filling pressures, and a very substantial influence at high levels of cardiac output. The demarcation between small and major effects appears in the upper range of normal filling pressures in this dynamic approach of the pericardial pressures.

Introduction: The relation between heart rate and age during the exercise test is dependent on the altitude over the sea level in which the test is made.

Objective: To observe the behavior of the heart rate during a maximal exercise test and its relation to age and to the altitude of Mexico City.

Method: Observational, non randomized study of 1,853 healthy subjects who underwent maximal exercise test done with Bruce's protocol, in the Department of Cardiology of the Spanish Hospital of Mexico City.

Results: The distribution by age groups showed a normal curve. They were divided by gender (67% males and 33% females) with a mean age of 47.6 +/- vs 49.6 +/- 13.7 years respectively (p = 0.003). Maximal heart rate according to gender (167.9 +/- 17.4 vs 160 +/- 18.2 bpm, p = 0.001). Trained vs sedentary (85.7% vs 14.3%). Maximal heart rate by grade of training (169.1 +/- 16.4 vs 167.6 +/- 17.8 bpm, p > 0.05) and the lineal correlation of maximal heart rate dependent on age of the subject (r-0.61, Y = 204.37 + (-0.810*X), p = 0.001).

Conclusions: The maximal heart rate during maximal exercise test at the altitude of Mexico City is lower than those reported in the literature. This is statistically significant and depends on age and it does not bear any relationship to the degree of training, at least in our subgroup of subjects studied. The same is true for females and the dependence on age remains the same too.

Aim: To search for cardiopulmonary (CP) kinetic and dynamic differences between Mexican resistance athletes (RES = 10) and non athletes (NON = 19).

Method: From the expired volume (Ve), measured by an open circuit spirometry, we calculated both VO2 and VCO2 during stress test while the volunteer pedalled seated on an electronic cycloergometer that started at 50 W.2 min-1 followed by increments of 25 W.2 min-1 each, until VO2máx was reached. The exercise transient time course (min) response (VO2, VCO2, Ve and heart rate, HR; and also O2 pulse, PulO2) was transformed to seconds and modelled by computer using linear regression technique by the interactive minimum squares method, and the mean response time (MRT) was used as an overall kinetic CP parameter.

Results: The transient MRTs for VO2, VCO2 and Ve were slow in RES compared to NON. While the transient CP dynamics in NON lasted MRT_VO2 < (MRT_PulO2, MRT_FC) < MRT_VCO2 < MRT_Ve; the RES: both MRT_PulO2 and MRT_HR shifted to the right ((MRT_VO2, MRT_VCO2) < (MRT_PulO2, MRT_FC) < MRT_Ve). The relationships between the best sport profit mean velocity and both the MRT_VO2, MRT_VCO2 and MRT_PulO2 (GEK = gas exchange kinetics) showed fast_RES and slow_GEK, and slow_RES and fast_GEK.

Conclusion: The transient CP kinetics was slow in RES compared NON. It is possible to distinguish cardiopulmonary kinetic differences among resistance athletes holding different sport profiles.

Hypertrophic cardiomyopathy (HCM) is a heterogeneous disease, characterized by asymmetric hypertrophy of the left and/or right ventricle with disarray of myocardial fibers. In order to know its clinical and electrocardiographic manifestation in the pediatric age group, we made a retrospective study of 24 cases from 1986 to 1995. There were: 15 girls and 9 boys, with a mean age of 6 years (age range: 1 month to 17 years). Clinical manifestations were dyspnea (71%), syncope (42%) and palpitations (42%). Physical examination disclosed an aortic systolic murmur in all patients, a mitral regurgitation in 42% and physical signs of congestive heart failure in 54% of patients. Chest X rays showed cardiac enlargement in 71% and pulmonary capillary hypertension in 42%. The most frequent ECG abnormalities were: a prolonged time in the intrinsecoid deflection onset on leads corresponding to the affected region, more or less deep and clean Q waves on leads aVF, aVL, V5 and V6, as well as supraventricular and ventricular rhythm disturbances in 11 patients (46%) with and without congestive heart failure. Bidimensional echocardiography confirmed antero-septal hypertrophy in all patients. The mortality rate was 17%. HCM is rare disease in the pediatric age group. Mortality increases when congestive heart failure and arrhythmias are present. Treatment must be individualized in all cases.

The deleterious effect of chronic or incessant supraventricular tachycardia on ventricular function is well-known and it has been demonstrated than can ultimately lead to dilated cardiomyopathy if unrecognized. Any variety of supraventricular tachycardia with chronic evolution may lead to left ventricular dysfunction, ectopic atrial tachycardia because of its persistent nature, often incessant and poorly responsive to antiarrhythmic drugs is a frequent cause of reversible congestive heart failure in patients without other demonstrable organic heart disease. Five patients (aged 14 to 52 years) were referred with symptoms of heart failure, NYHA functional class II (one patient), class III (one patient) and class IV (3 patients) associated with an incessant ectopic atrial tachycardia. Four patients underwent radiofrequency catheter ablation of the ectopic focus and one patient was treated with amiodarone. All patients were successfully treated and the echocardiographic assessment of left ventricular function indicated regression of the cardiomyopathy picture with recovery of systolic function, (mean left ventricular ejection fraction 39.2 +/- 6.1% before vs mean 62.4 +/- 4.8% after (p < 0.01). The clinical and echocardiographic picture of cardiomyopathy induced by incessant ectopic atrial tachycardia is reversible after successful treatment. This stresses the necessity of recognizing such arrhythmia as cause of primary heart failure.

Brugada's syndrome is one of the main causes of sudden death in young adults without a structural heart disease. This is an electrical cardiac illness secondary to a mutation of SCN5A gene of chromosome 3 that has a dominant autosomic transmission pattern. This mutation implies the dysfunction of the sodium channel that increases the Ito, loosing the dome of the epicardiac action potential phase two. An "all or none" repolarization pattern ensues and gives rise to a phase two reentry. This kind of reentry is responsible for the initiation and perpetuation of malignant ventricular arrhythmias among these patients. The clinical characteristics of the syndrome are the right bundle branch block, ST segment elevation from V1 to V3 leads and sudden death or syncope. In some patients, a pharmacological test must be done with ajmaline or procainamide to unmask the electrocardiographic changes. At present, the only effective treatment is the implantable cardioverter defibrillator (ICD). This device has the capability to reduce mortality from 40% annually to 0% at ten years. Pharmacological treatment is not useful.