Controlling antimicrobial activity and drug loading capacity of chitosan-based layer-by-layer films.

We report on layer-by-layer (LbL) films of chitosans (CHI) and hyaluronic acid (HA) whose properties could be controlled by employing chitosans with different degrees of deacetylation (DD¯ ≈ 85%; 65%; 40%) and high average molecular weight (ca. 106 g/mol). In spite of their high molecular weight, these chitosans are soluble within a wide pH range, including physiological pH. HA/CHI LbL films produced from polymer solutions at pH 4.5 were thinner, smoother, more hydrophilic than those prepared at pH 7.2. This is attributed to the more extended conformation adopted by chitosan due to its very high charge density at low pH, favoring a compact chain packing during the film formation and resulting in lower film thickness and roughness. The smoother HA/CHI LbL films obtained at pH 4.5 were effective against Escherichia coli, while the thicker, rougher LbL films fabricated at pH 7.2 could be used in the controlled released of Rose Bengal dye. In summary, the tuning of only two parameters, i.e. solution pH and DD¯ of chitosans, provides access to a library of HA/CHI LbL films for tailored, diversified applications.

Structural heart disease as the cause of syncope.

We described the clinical evolution of patients with structural heart disease presenting at the emergency room with syncope. Patients were stratified according to their syncope etiology and available scores for syncope prognostication. Cox proportional hazard models were used to investigate the relationship between etiology of the syncope and event-free survival. Of the 82,678 emergency visits during the study period, 160 (0.16%) patients were there due to syncope, having a previous diagnosis of structural heart disease. During the median follow-up of 33.8±13.8 months, mean age at the qualifying syncope event was 68.3 years and 40.6% of patients were male. Syncope was vasovagal in 32%, cardiogenic in 57%, orthostatic hypotension in 6%, and of unknown causes in 5% of patients. The primary composite endpoint death, readmission, and emergency visit in 30 days was 39.4% in vasovagal syncope and 60.6% cardiogenic syncope (P<0.001). Primary endpoint-free survival was lower for patients with cardiogenic syncope (HR=2.97, 95%CI=1.94-4.55; P<0.001). The scores were analyzed for diagnostic performance with area under the curve (AUC) and did not help differentiate patients with an increased risk of adverse events. The differential diagnosis of syncope causes in patients with structural heart disease is important, because vasovagal and postural hypotension have better survival and less probability of emergency room or hospital readmission. The available scores are not reliable tools for prognosis in this specific patient population.

Fetal tachyarrhythmia with 1:1 atrioventricular conduction. Adenosine infusion in the umbilical vein as a diagnostic test.

This is the report of a case of fetal tachyarrhythmia with 1:1 atrioventricular conduction detected by pre-natal echocardiography in a fetus at 25-weeks gestation. Adenosine infusion via cordocentesis was performed as a diagnostic test to differentiate between atrioventricular nodal reentrant supraventricular tachyarrhythmia and atrial flutter. After infusion, transient 2:1 atrioventricular dissociation was obtained and the diagnosis of atrial flutter was made. Transplacental therapy with digoxin and amiodarone was then successfully used.

Evaluation of the heart rate and arrhythmias following the maze procedure for chronic atrial fibrillation.

PURPOSE: To assess the presence and the prevalence of arrhythmias and the variability of the heart rate in the medium-term postoperative period following the maze procedure for chronic atrial fibrillation (AF). METHODS: Seventeen patients with a mean age of 51.7 +/- 12.9 years, who previously underwent the maze procedure without cryoablation for chronic atrial fibrillation, were evaluated with the 24 hour electrocardiogram (ECG)--Holter monitoring from the 6th month after the operation. Valvular and coronary procedures were concomitantly performed. RESULTS: The mean heart rate during Holter monitoring was 82 +/- 8 bpm; the maximal heart rate was 126 +/- 23 bpm and the minimal heart rate 57 +/- 7 bpm. Sinus rhythm was found in 10 (59%) patients and atrial rhythm was found in 7 (41%). Supraventricular extrasystoles had a rate of 2.3 +/- 5.5% of the total number of heartbeats and occurred in 16 (94%) patients. Six (35%) patients showed nonsustained atrial tachycardia. Ventricular extrasystoles, with a rate of 0.8 +/- 0.5% of the total heartbeats, occurred in 14 (82%) patients. The chronotropic competence was normal in 9 (53%) patients and attenuated in 8 (47%). The atrioventricular conduction (AV) was unchanged in 13 (76%) patients and there were 4 (24%) cases of first degree atrioventricular block (AVB). CONCLUSION: After the maze procedure, the values for the mean heart rate, AV conduction and chronotropic competence approach the normal range, although some cases show attenuation of the chronotropic response, first degree AV block or benign arrhythmias.

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.

[Fetal supraventricular tachyarrhythmias. Experience of a fetal cardiology referral center]. / Taquiarritmias supraventriculares no feto. Experiência de uma unidade de referência em cardiologia fetal.

PURPOSE: To describe the presentation, diagnosis and treatment of fetal supraventricular tachyarrhythmias in a series of fetuses followed in a tertiary Fetal Cardiology Center. METHODS: Twenty-five fetuses with diagnosis of supraventricular tachyarrhytmia were reported from January 1989 to October 1997, among 3117 pregnant women referred for fetal cardiac evaluation. RESULTS: There were 17 fetuses with the diagnosis of supraventricular tachycardia (SVT) and 8 patients with atrial flutter (AF). Gestational age ranged from 26 to 40 weeks. Twelve patients were hydropic at presentation (6 with SVT and 6AF). Four fetuses with SVT showed structural abnormalities (two with Ebsten's anomaly and two with VSD). All patients were admitted to the Fetal Cardiology Unit for monitoring and treatment. Among 17 fetuses with SVT, twelve showed good response to digoxin administration, but this drug was not useful in any of the patients with flutter. In two patients with SVT and in six with AF, the pregnancy was interrupted to perform post-natal cardioversion. The mortality rate was 3/17 in the SVT group (including 2 patients with ebstein's anomaly and 0/8 in the flutter group) CONCLUSION: Fetal supraventricular tachyarrithmias are rare in the general population. Nevertheless, the fetus may present with severe heart failure and death. Considering the satisfactory therapeutic response, accurate diagnosis and early treatment of these conditions are extremely important.

Radiofrequency ablation of bundle branch reentrant tachycardia in a patient with atrial septal defect.

A 22-year-old woman with an atrial septal defect surgically corrected during childhood presented with a wide QRS complex tachycardia with left bundle branch block morphology. Electrophysiological study was performed and bundle branch reentrant tachycardia was induced with morphology identical to clinical tachycardia. Radiofrequency catheter ablation of the right bundle branch was successful, resulting in complete right bundle branch block and cure of her ventricular arrhythmia.