Stability of focusing regions and its vortex-solitonic properties.

Focusing regions, also known as caustic regions, are the singular solutions to the amplitude function of optical fields. Focusing regions are generated by the envelope curve of a set of critical points, which can be of attractor or repulsor type. The nature of the critical point depends on the refractive index. An important property of the critical points is that they present charge-like features. When a focusing region is generated in media with a random refractive index, current-like effects appear, and the evolution of the focusing regions follows a diffusion behavior. The morphology of the focusing regions may generate vortices or "eternal solutions" of solitonic type in a nonlinear medium. Herein, the condition under which these effects occur is analyzed and experimentally corroborated.

[Use of intravenous esmolol in patient with severe heart failure and abnormal intraventricular gradient after aortic valve replacement]. / Uso de esmolol intravenoso en un paciente con insuficiencia cardíaca severa y gradiente intraventricular izquierdo anormal postsustitución valvular aórtica.

The presence of anomalous intraventricular flows of high velocity and dynamic ejective obstruction of the left ventricle post aortic valve replacement, generally by severe aortic stenosis, is a relatively infrequent, but severe complication. An early diagnosis is of crucial importance, since the usual treatments applied to postoperative heart failure are often inefficacious or even harmful. Even in cases of severe pump failure, when the clinical case is diagnosed adequately, endovenous short-action beta-blockers are useful.

Comparison of dobutamine ECG stress test with predischarge exercise test after acute myocardial infarction.

Exercise testing after acute myocardial infarction is commonly used, but in recent years alternative methods have been proposed. Standard exercise testing was compared with dobutamine electrocardiographic (ECG) stress testing in 100 patients after an acute initial myocardial infarction. Dobutamine ECG stress testing was performed in a standard manner at 5 +/- 1 days after the infarction and exercise testing was performed a mean of 10 +/- 2 days following the event. Agreement between both tests was observed in 91 cases (91%), P < .001, Fisher test kappa value, 0.79). The dobutamine test predicted the result of the exercise test with a sensitivity of 100% (95% confidence interval, 87-100) and a specificity of 88% (95% confidence interval 77-93) for a positive predictive value of 75% (95% confidence interval, 62-97) and a negative predictive value of 100% (95% confidence interval, 91-100). Dobutamine ECG stress testing is concluded to be an objective and reliable procedure, which accurately predicts the results of standard exercise testing. It is inexpensive, easy to perform, and although not yet confirmed, could be particularly useful in patients who cannot perform exercise.

Comparison of dobutamine electrocardiographic stress test and exercise test in two different groups of patients with unstable angina.

Exercise testing is a well known means of evaluating patients with unstable angina, but in recent years, alternative methods have been proposed. We prospectively compared standard exercise testing with dobutamine electrocardiographic stress testing for patients who were admitted with a diagnosis of unstable angina. A total of 43 patients were studied, divided into two different groups, according to the presence (group A n = 26) or absence (group B n = 17) of a previous history of coronary artery disease and/or electrocardiographic changes compatible with ischemia on admission. Dobutamine electrocardiographic stress testing was performed in a standard manner at 3 +/- 1 days after admission in group A and at 16 +/- 8 hours after admission in group B. Exercise testing was performed, on average 5 +/- 1 days following the event in group A and 2 days after admission in group B. Agreement between both tests was observed in 39 (91%) cases, Kappa value: 0.81. The dobutamine test predicted the result of the exercise test with a sensitivity of 79% (95% CI 54-90), and a specificity of 100% (95% CI 86-100), with a positive predictive value of 100% and a negative predictive value of 86%. It can be concluded that dobutamine electrocardiographic stress testing is an objective and reliable procedure that accurately predicts the results of standard exercise testing in patients with a diagnosis of unstable angina. If this result were confirmed with a greater number of patients, it would be a good option for definitive diagnosis and risk stratification, in addition to being inexpensive and easy to perform. It can also be particularly useful for patients who cannot perform exercise.

[Effect of diltiazem on cold-induced left ventricular dysfunction in patients with systemic sclerosis]. / Efecto del diltiazem sobre las alteraciones cardíacas inducidas por el frío en la esclerosis sistémica.

Patients with systemic sclerosis (SS) have cardiac dysfunction induced by cold exposure. We and others have demonstrated this finding after corporal chilling, suggesting a "coronary Raynaud phenomenon" mediated by intermittent vascular spasm. In this study we evaluated the effect of diltiazem (DTZ) in cardiac dysfunction induced by cold test in patients with SS without clinical evidence of heart disease. Twelve patients with SS were studied. One patient was excluded because he did not fulfill the prescribed treatment. Eleven patients (age of 49.9 +/- 3.8 years and illness duration of 9.3 +/- 4.8 years) were included. Gated equilibrium radionuclide ventriculography was recorded after red blood cells were labeled in vivo using an intravenous injection of stannous pirophosphate followed by 20 mc of 99 Tc (gamma camera with electrocardiographic R wave gating was used). Left ventricular injection fraction (LVEF) was calculated using computer analysis and wall motion abnormalities by visual interpretation. Patients were cooled using a thermic blanket set at 5 degrees centigrade. They were evaluated before and after a period of cooling. After corporal chilling LVEF decreased more than 10% in all of them. DTZ 270 mg a day was administered to the same patients during 48 hs. Basal and cold LVEF were repeated in all patients. The results with and without DTZ were compared by Student's t Test. The basal LVEF with and without DTZ was not different (64.8 +/- 2.6 and 63.1 +/- 1.8). After corporal chilling LVEF decreased (64.8 +/- 2.6 to 54.8 +/- 2.5 p < 0.00001) and reversible abnormalities in wall motion were noticed in patients without DTZ. When they received DTZ neither difference in LVEF (63.1 +/- 1.8 to 62.1 +/- 2.4) nor wall motion abnormalities were observed. We compared the LVEF after chilling (62.1 +/- 2.4 and 54.8 +/- 2.5) and we found an important difference with the use of DTZ (p < 0.005). It can be concluded that in patients with SS and no overt heart disease, DTZ prevents the early cardiac dysfunction induced by cold test. Probably this drug blunts the coronary spasm induced by cold test in this group of patients.

[Bacteremic urinary infection in men: comparative study with bacteremic pyelonephritis in women]. / Infección urinaria bacteriémica en el varón. Estudio comparativo frente a la pielonefritis bacteriémica femenina.

OBJECTIVE: To compare the clinic and microbiologic characteristics of the extrahospitalary bacteremic urinary infections (EBUI) between men and women assisted in a 200 bed community hospital. PATIENTS AND METHODS: A prospective study of the EBUI diagnosed in our hospital from January 1991 to April 1994 was carried out. Quantitative variables were evaluated with t Student analysis, chi 2 was used for the comparation of proportions. The logistic regression step-by-step model was used in order to find out which variables influenced that the microorganism causing EBUI was Escherichia coli. RESULTS: 107 episodes of EBUI were recorded, 39 men and 68 women, with the same microorganism in blood and urine. Significative diferences in age (70 +/- 17 years in men, 58 +/- 24 years in women); the presence of urinary tract alterations (49% men vs 12% women) and in the presence of indwelling urinary catheter (26% men vs 3% female) were found. E. coli was responsible in a major proportion (p = 0.03) of the EBUI in women that in men, but only age > 65 was selected as explaining variable with the logistic regression model. CONCLUSIONS: The EBUI appears in old men with urinary tract alterations and/or manipulations, clearly different from the EBUI in women. Age greater than 65 years is the only predisponent factor of EBUI in men by bacteria other than E. coli.