Francisco Torres

Balloon-expandable stent repair of severe coarctation of aorta

Experimental studies have shown that stents implanted at the aorta become incorporated within the aortic wall and can be further expanded in growing animals. This study evaluates the feasibility and immediate results of balloon-expandable stent implantation in 10 patients with severe coarctation of aorta. The ages of the patients ranged from 1 month to 43 years; 1 was an infant, 8 were children (mean age 5.3 +/- 4 years), and 1 was an adult. All had an unfavorable anatomy for balloon angioplasty; 9 had isthmus hypoplasia. Balloon predilation was first performed and its immediate effect evaluated. Then a balloon-expandable stent that was 30 mm long and covered the isthmus and coarctation levels was deployed, and it was further expanded to the preselected final diameter (12 +/- 4 mm). A final hemodynamic and angiographic evaluation was then obtained. Full deployment of an incompletely expanded and distally displaced stent in the infant led to aortic disruption that was controlled by a second stent covering the disrupted zone and the isthmus. After balloon angioplasty alone was done, the mean gradient (43 +/- 12 vs 31 +/- 10 mm Hg) and the percentage stenosis (72% +/- 11% vs 54% +/- 11%) had an insufficient decrease. However, after stent implantation was done, the gradient almost disappeared (mean 2 +/- 3 mm Hg). The angiographic stenosis disappeared in 7 patients and was markedly reduced in 3. The ratio of isthmus/descending aorta changed from 0.65 +/- 0.14 to 1 +/- 0.08 (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and hemodynamic predictors of survival in patients aged <65 years with severe congestive heart failure secondary to ischemic or nonischemic dilated cardiomyopathy

To identify which clinical or hemodynamic parameters predict survival in patients with end-stage heart failure due to dilated cardiomyopathy, 130 consecutive patients aged < 65 years (mean 46 +/- 13) assessed for heart transplantation from May 1986 to April 1991 were studied. Mean follow-up was 15 +/- 11 months. Left ventricular ejection fraction was 22 +/- 7%. Left ventricular end-diastolic pressure was 27 +/- 9 mm Hg, and cardiac index was 2.2 +/- 0.6 liter/min/m2. Symptom class was IV in 91% of patients and III in 9%. Etiology was ischemic in 40% of patients and idiopathic in 60%. After intensive medical therapy, heart transplantation was considered indicated in 53% of patients, contraindicated in 20% and not indicated in 27%. Transplantation was performed in 36% of patients during follow-up, and 35% died and 29% were alive without transplantation. A comparison, excluding patients with transplantation, was performed between those who were alive and had survived > or = 6 months after assessment, and those who died. On multivariate analysis, the following 3 parameters were independent predictors of prognosis: intravenous inotropic requirement (p < 0.001), maximal, tolerated captopril dose (p = 0.013) and systolic blood pressure (p = 0.003). When patients with transplantation were considered as deaths, stabilization on medical therapy also reached statistical significance (p = 0.009). Classic prognostic markers including ventricular arrhythmias, left ventricular end-diastolic pressure, cardiac index, amiodarone therapy and etiology were not associated with prognosis in this homogeneous population of severely ill patients.

Follow-up patency of side branches covered by intracoronary Palmaz-Schatz stent

To assess the risk of late side branch occlusion after Palmaz-Schatz stent deployment, we analyzed the angiographic evolution of 62 patients treated by successful stent implantation who had a total of 85 side branches starting from the stented segment. Side branches were considered minor (n = 39) when the diameter was < 1 mm and intermediate (n = 46) when the vessel had > or = 1 mm diameter. One angiographic follow-up study was available in all patients at 8 +/- 5 months. Eight minor branches presented some degree of stenosis at origin before stent deployment (4 totally occluded). After stent deployment, 32 (82%) of 39 remained unchanged and 3 became occluded. Late progression at origin occurred in 4 of 34 (3 occluded). Before stent deployment, 48% of the intermediate branches had some compromise degree at their starting point (1 totally occluded). Eight of 45 intermediate branches became occluded after stent implantation. Late progression at origin happened in 5 of 32 branches (2 occluded). Some degree of follow-up stenosis regression at the origin was observed in 22 (26%) of 85 arteries. Neither clinical nor angiographic factors could be identified as predictors of late side branch occlusion or stenosis progression at its origin. Later occlusion or progression at origin of a side branch covered by a Palmaz-Schatz stent seems to be an uncommon occurrence (7% and 12% respectively) that cannot be predicted by angiographic or clinical factors. On the contrary, regression at follow-up of a side branch-origin stenosis can also come about.

Factores de riesgo asociados a endocarditis sin cardiopatía predisponente

La patogenia de la endocarditis infecciosa (EI) ha cambiado en las ultimas decadas, siendo cada vez mayor el numero de casos sin cardiopatia predisponente. El objetivo de este trabajo es conocer las caracteristicas de los pacientes no drogadictos afectados de EI sin cardiopatia predisponente e identificar los posibles factores de riesgo para la infeccion. De 196 casos de EI, 49 (25%) ocurrieron en pacientes sin cardiopatia predisponente. Se identifico en la mayoria (26 casos) un factor de riesgo para la infeccion, predominando las enfermedades digestivas (6 casos), hemodialisis (6 casos) y cateteres venosos centrales (4 casos). La infeccion se localizo con mayor frecuencia en las valvulas derechas (29 frente a 6%; p

Improved diagnostic value of combined time and frequency domain analysis of the signal-averaged electrocardiogram after myocardial infarction

BACKGROUND Time domain analysis (TD) of the signal-averaged electrocardiogram (SAECG) presents a higher incidence of false positives in inferior myocardial infarction (MI), whereas spectral turbulence analysis (STA) suffers from a higher incidence of false positives in anterior MI. We investigated the hypothesis that a combined TD and STA (TD+STA) analysis of the SAECG could improve its predictive accuracy for major arrhythmic events (MAE) after MI. METHODS Signal-averaged electrocardiograms were prospectively recorded 10.1 +/- 2.6 days after acute MI in 602 patients. Time domain analysis and STA were performed using standard parameters and criteria for abnormality. For the combined TD+STA model, stepwise discriminant analysis was utilized to optimize prediction of MAE. Receiver operating characteristic curves were utilized to optimize cutoff values for each SAECG parameter separately, and also for the combined TD+STA model. RESULTS During a one-year follow-up period, 38 patients had MAE: 14 sustained ventricular tachycardia, 2 resuscitated ventricular fibrillation and 22 sudden cardiac deaths. The total predictive accuracy of combined TD+STA (89.9%) was significantly higher than TD (75.1%) or STA (77.6%). The negative predictive accuracy of all three analyses was high (98%). The positive predictive accuracy of TD (19.6%) or STA (18.3%) was quite low, and significantly improved to 35.8% by combined TD+STA analysis. The positive predictive accuracy of TD+STA improved to 51.2% in patients with left ventricular ejection fraction <40%. CONCLUSIONS Combined TD + STA analysis of the SAECG significantly improves its prognostic ability for MAE in post-MI patients compared with TD or STA analyzed separately.

Reproducibility of time-domain and three different frequency-domain techniques for the analysis of the signal-averaged electrocardiogram.

Because time-domain (TD) analysis of the signal-averaged ECG (SAECG) has some limitations that limit its use, several frequency-domain analysis techniques were developed in an attempt to improve the diagnostic ability of the SAECG. However, it is not known how reliable these techniques are at detecting late potentials. This prospective study compares the short-term reproducibility of 4 analysis techniques: TD analysis, spectral temporal mapping (STM), spectral turbulence analysis (STA), and acceleration spectrum analysis (ASA), in a large series of normal patients and post-myocardial infarction (MI) patients. Two consecutive SAECGs were recorded in 634 patients that were divided into 3 groups: 117 remote MI patients undergoing programmed electrical stimulation for the inducibility of ventricular tachycardia (Group 1), 407 consecutive acute MI survivors (Group 2), and in 110 healthy volunteers (Group 3). The diagnostic reproducibility of the 4 techniques was evaluated by comparing rates of inconsistent results (1 normal and the other abnormal). The numeric reproducibility for each technique was assessed by comparing the normalized differences of each single SAECG parameter between the 2 recordings. Inconsistent results of diagnostic reproducibility were observed in 4.1%, 6.9%, 9.8%, and 18.0%, with TD, STA, ASA, and STM, respectively. Comparisons of these rates were significantly different (P < .05) except between STA and ASA (P = .07). The numeric reproducibility was highest for TD parameters, lowest for STM factors of normality, and intermediate for STA and ASA indices. TD analysis remains the most reproducible SAECG analysis technique, whereas STM showed the worst reproducibility, which limits its clinical applicability. STA and ASA provide an acceptable intermediate reproducibility, the former being slightly, although not significantly, more reproducible than the latter.

Características clínicas y evolución de la endocarditis infecciosa recurrente en no drogadictos

Introduccion y objetivos La recurrencia de enfermedad se presenta en una considerable proporcion de enfermos con endocarditis infecciosa, pudiendo tratarse de un factor que aumente el numero de complicaciones. El objetivo de nuestro trabajo fue evaluar si existen caracteristicas diferenciales entre los episodios unicos y los repetidos de endocarditis, asi como estudiar cual es la evolucion y el pronostico de la endocarditis recurrente en nuestro medio. Pacientes y metodo Revisamos de forma prospectiva nuestra serie de 13 episodios de recurrencia de endocarditis entre un total de 196 casos en pacientes no adictos a drogas por via intravenosa diagnosticados de endocarditis infecciosa en nuestros centros entre 1987 y 2000. Resultados No encontramos diferencias significativas entre los pacientes con endocarditis recurrente y aquellos con un primer episodio de enfermedad en cuanto a la edad de presentacion, el sexo, la valvula afectada o el germen causal. Si encontramos una mayor frecuencia de pacientes portadores de protesis valvular en las endocarditis recurrentes (86% vs 27%; p La mortalidad global alcanzo un 53% en los casos de recurrencia, en comparacion con el 27% de los primeros episodios (p Conclusiones La endocarditis recurrente supone el 7% de casos de nuestra serie. Sus caracteristicas son similares a las de los primeros episodios, con excepcion de una mayor frecuencia de endocarditis protesica y una mortalidad global mayor.

Parámetros de Interacción Iónica de las Soluciones Acuosas Concentradas del Líquido Iónico Trifluorometanosulfonato de 1-Etil-3-Metil-Imidazolio a Varias Temperaturas

Resumen Se determinaron experimentalmente las densidades de las soluciones acuosas concentradas de la mezcla binaria agua + trifluorometanosulfonato de 1-etil-3-metil-imidazolio ([Emim + ][CF 3 SO 3 - ]) a las temperaturas de 283.15 a 318.15 K, usando un densimetro de tubo vibratorio Anton Paar modelo DMA 5000. Se calcularon los volumenes molares aparentes y se correlacionaron con las ecuaciones de Pitzer-Simomson usando como estado de referencia al liquido ionico puro y el soluto a dilucion infinita, y con los modelos de Pitzer-Simomson-Clegg y Pitzer-Simomson-Clegg simplificado, cuyo estado de referencia es el liquido ionico puro. El coeficiente de correlacion resulto positivo y cercano a uno, lo cual indica que existe una correlacion directa, entre los volumenes molares aparentes experimentales y calculados para todos los casos. Sin embargo, los resultados de la correlacion muestran que los volumenes molares aparentes se ajustan mejor a la ecuacion de Pitzer-Simomson.

PROPIEDADES VOLUMÉTRICAS DE LA DL-ALANINA EN SOLUCIONES ACUOSAS DE TETRAFLUOROBORATO DE 1-BUTIL, 3-METILIMIDAZOLIO A DIFERENTES TEMPERATURAS

Densities of DL-alanine in aqueous ionic liquid, 1-butyl, 3-methylimidazolium tetrafluoroborate solutions were measured from 283.15 to 313.15 K. The densities measured were used to calculate apparent molar volumes (VΦ), apparent molar volume limits (VΦ0), transfer molar volume limits (ΔVΦ0) and hydration number (NH). The behavior of (ΔVΦ0) was interpreted in terms of solute-solvent interactions on the basis of the cosphere overlap model. The hydration numbers were positive and explained by dehydration and electrostriction.