Atrial fibrosis and decreased connexin 43 in rat hearts after exposure to high-intensity infrasound.

BACKGROUND: Noise is an important environmental risk factor. Industrial environments are rich in high-intensity infrasound (hi-IFS), which we have found to induce myocardial and coronary perivascular fibrosis in rats. The effects of exposure to IFS on the ventricles have been studied, but not on the atria. We hypothesized that rats exposed to hi-IFS develop atrial remodeling involving fibrosis and connexin 43, which we sought to evaluate. MATERIAL AND METHODS: Seventy-two Wistar rats, half exposed to hi-IFS (120 dB, <20 Hz) during a maximum period of 12 weeks and half age-matched controls, were studied. Atrial fibrosis was analyzed by Chromotrope-aniline blue staining. The immunohistochemical evaluation of Cx43 was performed using the polyclonal antibody connexin-43 m diluted 1:1000 at 4 °C overnight. Digitized images were obtained with an optical microscope using 400× magnifications. The measurements were performed using image J software. A two-way ANOVA model was used to compare the groups. RESULTS: The mean values of the ratio "atrial fibrosis / cardiomyocytes" increased to a maximum of 0.1095 ± 0,04 and 0.5408 ± 0,01, and of the ratio "CX43 / cardiomyocytes" decreased to 0.0834 ± 0,03 and 0.0966 ± 0,03, respectively in IFS-exposed rats and controls. IFS-exposed rats exhibited a significantly higher ratio of fibrosis (p < .001) and lower ratio of Cx43 (p = .009). CONCLUSION: High-intensity infrasound exposure leads to an increase in atrial interstitial fibrosis and a decrease in connexin 43 in rat hearts. This finding reinforces the need for further experimental and clinical studies concerning the effects of exposure to infrasound.

Pediatric liver transplantation in Latin America: Where do we stand?

LT started in LA in 1968, and pediatric LT records are available starting in the 1990s. Currently, eight countries perform pediatric LT in LA. Registries by national organizations fail to report robust data on pediatric LT. The aim of this paper was to report on the pediatric LT activity in LA. Data were gathered retrospectively through information available in the national registries websites and from local centers. Of the eight countries that report pediatric LT activity, Brazil, Argentina, Mexico, and Colombia have adequate registries of the numbers of LT performed. These countries concentrate most of the activity for pediatric LT. A total of 4593 pediatric LT were reported in LA. Websites for national organizations do not provide open data on post-transplant survival rates or waiting list mortality. The information herein is based on reports by local centers. Overall, survival from select centers is similar to that reported on North American and European registries, between 80 and 90% in the first year post-transplant. In conclusion, pediatric LT activity is growing in LA, especially in Brazil and Argentina. However, the lack of an appropriate LA registry restricts the assessment of quality and therefore restricts interventions aimed at quality improvements in different regions.

Histomorphometric evaluation of the small coronary arteries in rats exposed to industrial noise.

UNLABELLED: Morphological changes induced by industrial noise (IN) have been experimentally observed in several organs. Histological observations of the coronary arteries showed prominent perivascular tissue and fibrosis among IN-exposed rats. The effects on the small arteries are unknown. OBJECTIVE: To evaluate the histomorphometric changes induced by IN on rat heart small arteries. METHODS: Twenty Wistar rats exposed to IN during a maximum period of seven months and 20 age-matched controls were studied. Hearts were transversely sectioned from ventricular apex to atria and a mid-ventricular fragment was selected for analysis. The histological images were obtained with an optical microscope using 400× magnifications. A total of 634 arterial vessels (298 IN-exposed and 336 controls) were selected. The mean lumen-to-vessel wall (L/W) and mean vessel wall-to-perivascular tissue (W/P) ratios were calculated using image J software. RESULTS: There were no differences between exposed and control animals in their L/W ratios (p=0.687) and time variations in this ratio were non-significant (p=0.110). In contrast, exposed animals showed lower W/P ratios than control animals (p<0.001), with significant time variations (p=0.004). CONCLUSIONS: Industrial noise induced an increase in the perivascular tissue of rat small coronary arteries, with significant development of periarterial fibrosis.

Chronic hepatitis E virus infection in a pediatric female liver transplant recipient.

We describe a case of chronic hepatitis E virus (HEV) infection in a 13-year-old female liver transplant recipient with recurrent increased aminotransferase levels and acute cellular rejection. This finding demonstrates that chronic HEV infection can occur and should be further investigated in immunocompromised patients in Latin America.

Histomorphometric evaluation of the coronary artery vessels in rats submitted to industrial noise.

INTRODUCTION: Industrial noise (IN) is characterized by high intensity and a wide spectrum of wavelengths that induce physical vibration on the body structures. This effect, resulting from the low-frequency sound waves, can lead to pathological alterations in the extracellular matrix with an abnormal proliferation of collagen and development of tissue fibrosis, in the absence of an inflammatory process. OBJECTIVE: The aim of this study was to evaluate the modifications of the arterial coronary vessels in Wistar rats submitted to IN. METHODS: Two groups of rats were considered: group A with 20 rats exposed to IN during a maximum period of 7 months; group B with 20 rats as age-matched controls.The hearts were sectioned from the ventricular apex to the atria and the mid-ventricular fragment was selected. Haematoxylin-eosin and Masson's trichrome staining were used for histological observation. Histomorphometric evaluation of the coronary vessels was performed using the computer image analysis ImageJsoftware. The mean lumen-to-vessel wall (L/W) and media vessel wall-to-perivascular tissue (W/P) ratios were calculated in each group. RESULTS: Histological evaluation showed a prominent perivascular tissue with fibrotic development in the absence of inflammatory cells in group A. Histomorphometric analysis showed that the mean L/W was 0.7297 and 0.6940 in group A and B, respectively. The mean W/P ratio was 0.4923 and 0.5540 in group A and B, respectively, being higher in the control group (P <0.01). CONCLUSIONS: There are perivascular structural modifications in arterial coronary vessels. Our results show a significant development of periarterial fibrosis induced by industrial noise in the rat heart.

Myocardial fibrosis in rats exposed to low frequency noise.

UNLABELLED: Low frequency noise (LFN) characterized by large pressure amplitude (> or =90 dB SPL) and low frequency bands (< or =500 Hz) can lead to structural and ultrastructural modifications in the extracellular matrix of several tissues, with an abnormal proliferation of collagen and development of fibrosis. It is not known whether LFN induces similar structural alterations in the ventricular myocardium of rats. OBJECTIVE: The aim of this study was to evaluate and measure the myocardial fibrosis induced by LFN. METHODS: Two groups of rats were considered: group A with 26 rats continuously exposed to LFN during a period of 3 months; group B with 20 control rats.The hearts were sectioned from the ventricular apex to the atria and the mid-ventricular fragment was selected. Chromotrope-aniline blue (CAB) staining was used for histological observation. The measurement of fibrosis was performed using the computer image analysis Image J software. RESULTS: Histological observation with CAB staining showed the presence of collagen deposition between the cardiomyocytes. Fibrosis increased 97.5%, 81.5% and 83.7%, respectively, in the left ventricle, interventricular septum and right ventricle, in exposed rats (P <0.001).The ratio fibrosis/muscle in left ventricle, interventricular septum and right ventricle was significantly higher in LFN exposed rats (P< 0.001). CONCLUSIONS: Our study demonstrates a significant myocardial fibrosis induced by low frequency noise in rats. Our results reinforce the need for further experimental and clinical investigations concerning the effects of low frequency noise on the heart.

[High-degree atrioventricular block induced by Prinzmetal angina]. / Bloqueio aurículo-ventricular de alto grau induzido por angina de Prinzmetal.

We present the case of a 46-year-old woman with episodes of chest pain with ST-T segment elevation and paroxysmal high-degree atrioventricular block and syncopal episodes. Coronary angiography revealed no significant atheromatous lesions. The patient was treated with nitrates and calcium channel blockers but syncopal episodes with atrioventricular block persisted. A DDD-R pacemaker was implanted and four-month follow-up was uneventful.

Raising awareness and early detection of atrial fibrillation, an experience resorting to mobile technology centred on informed individuals.

BACKGROUND: Atrial fibrillation (AF) is a cardiac arrhythmia responsible for one third of ischemic strokes. Early detection of AF plays an important role in preventing embolic stroke. OBJECTIVES: This study aimed to test the feasibility of an awareness event including opportunistic screening for atrial fibrillation; and to test the reliability of the innovative portable electrocardiogram (ECG) device used. METHODS: An awareness campaign was held during two weeks, where individuals consenting to participate in a pharmacist-led detection event, received a manual pulse check, were clinically evaluated and subject to a single-lead electrocardiogram using AliveCor Kardia® mobile. ECGs highlighted as possible AF were confirmed by the cardiologist and those signalled with abnormalities in cardiac rhythm were referred to their physician. Data were collected in a password protected application and analyzed using SPSS, v.24. The Kardia® mobile's sensitivity and specificity was tested against the standard 12-lead ECG. RESULTS: The awareness event involved 223 individuals, among which 205 were screened. Mean age was 66 years (SD = 15) and hypertension was the most frequently reported (n = 107; 52.2%). Mean CHAD2DS2- VASc score was 3 (SD = 1.8). Cardiac irregularities were identified in 45 individuals, 14 confirmed to be new cases of AF (6.8%) by the cardiologist. The sensitivity and specificity were 90.9% and 97.4%. CONCLUSION: Data suggests this device to be potentially useful for opportunistic early detection of AF, provided interprofessional collaboration is guaranteed so that suspect cases are adequately managed and in a timely way. Fourteen new cases of AF were identified in the population studied, suggesting the pharmacist working in a multiprofessional context, may have had an important role in preventing potential ischemic-related strokes with this initiative. All healthcare professionals involved in the patient pathway should play a more active role in contributing to better health outcomes, particularly within primary care.

Head-up tilt testing with different nitroglycerin dosages: experience in elderly patients with unexplained syncope.

AIMS: Protocols using sublingual nitrates have been increasingly used to improve diagnostic accuracy of head-up tilt testing (HUT). Nevertheless, exaggerated responses to nitrates have been frequently described, particularly in elderly patients. The aim of this article is to evaluate, in an elderly population with unexplained syncope, whether the impact of sublingual nitroglycerin (NTG) used as a provocative agent is dose-dependent. METHODS AND RESULTS: One hundred and twenty consecutive elderly patients submitted to HUT using NTG after an asymptomatic drug-free phase were studied. Patients were divided into three groups according to the NTG dosage: 500, 375 and 250 microg. The test was considered positive when there was reproduction of symptoms with bradycardia and/or arterial hypotension. A gradual decrease in the blood pressure after NTG was considered an exaggerated response to nitrates. There were no differences in the clinical characteristics of the different subgroups. A positive test was obtained in 50% of the patients in each group. The rate of exaggerated responses was identical in all groups and ranged between 15 and 17%. CONCLUSION: In an elderly population with syncope of unknown origin submitted to HUT, the response to NTG is not dose-dependent, and no difference was found in the rate of exaggerated responses to nitrates with different NTG dosages.

Enterotoxigenic and nontoxigenic Bacteroides fragilis strains isolated in Brazil.

The presence of enterotoxigenic Bacteroides fragilis and nontoxigenic B. fragilis (NTBF) among 109 strains isolated from 1980-2008 in Brazil were investigated by PCR. One strain, representing 0.9% of the total analyzed strains, harbored the bft gene which was identified as bft-1 isoform based on PCR-RFLP and sequencing. Forty-nine strains (44.9%) exhibited the NTBF pattern III which possesses the flanking region required for pathogenicity island acquisition in which the bft gene is codified. These data reinforce the potential of B. fragilis as an emerging enteropathogen in our country.

False positive responses to head-up tilt testing in elderly patients with paroxysmal atrial fibrillation.

UNLABELLED: The autonomic nervous system (ANS) plays a role as a modulator in the pathogenesis of paroxysmal atrial fibrillation (PAF). The clinical pattern of vagally mediated PAF has been observed mainly in young patients. Neurocardiogenic responses during orthostatic stress are related to autonomic reflexes in which the vagal influence predominates. AIM: To evaluate the susceptibility of elderly patients with PAF to activation of vasovagal syncope mechanisms. METHODS: We performed passive head-up tilt testing (HUT) in 34 patients (62% women, aged 72 +/- 7 years), with > or = 1 year of clinical history of PAF--19 without structural heart disease, 11 with hypertensive heart disease and 4 with coronary artery disease (who had no previous myocardial infarction, had undergone myocardial revascularization, and had no documented ischemia) (PAF group), and compared the results with those obtained in a group of 34 age-matched patients (53% women, aged 74 +/- 6 years), who underwent HUT due to recurrent syncope (Sc group). In this group, 21 had no documented heart disease and none had a clinical history of AF. There was no diabetes, congestive heart failure or syncope in the PAF group. After a supine resting period, the subjects were tilted at 70 degrees for 20 minutes while in sinus rhythm. No provocative agents were used to complement the HUT. ECG and blood pressure were continuously monitored (Task Force Monitor, CNSystems). The test was considered positive when syncope or presyncope occurred with bradycardia and/or arterial hypotension. Abnormal responses were classified as cardioinhibitory, vasodepressor or mixed. RESULTS: HUT was positive in seven patients of the PAF group--vasodepressor response in five and mixed in two (20.5% of the total; 26.3% of those without heart disease)--and in eight patients (vasodepressor in six and mixed in two) of the Sc group (p=NS). During HUT, three patients of the PAF group had short periods of self-limited PAF (in one, after vasodepressor syncope). There were no differences in gender distribution, age or heart disease. No cardioinhibitory responses or orthostatic hypotension were observed. CONCLUSION: In elderly patients with PAF, a significant number of false positive results during passive HUT may be expected, suggesting increased vasovagal reactions despite aging. This suggests that ANS imbalances may be observed in this population.

Infrasound induces coronary perivascular fibrosis in rats.

BACKGROUND: Chronic exposure to industrial noise is known to affect biological systems, namely, by inducing fibrosis in the absence of inflammatory cells. In rat hearts exposed to this environmental hazard, we have previously found myocardial and perivascular fibrosis. The acoustic spectrum of industrial environments is particularly rich in high-intensity infrasound (<20 Hz), whose effects on the heart are unknown. We evaluated the morphological changes induced by IFS in rat coronaries in the presence and absence of dexamethasone. METHODS: Adult Wistar rats were divided into three groups: group A (GA)-IFS (<20 Hz, 120 dB)-exposed rats for 28 days treated with dexamethasone; group B (GB)-IFS-exposed rats; group C (GC)-age-matched controls. The midventricle was prepared for observation with an optical microscope using 100× magnification. Thirty-one arterial vessels were selected (GA 8, GB 10, GC 13). The vessel caliber, thickness of the wall, and perivascular dimensions were quantified using image J software. Mann-Whitney and Kruskal-Wallis tests were used to compare the groups for lumen-to-vessel wall (L/W) and vessel wall-to-perivascular tissue (W/P) ratios. RESULTS: IFS-exposed rats exhibited a prominent perivascular tissue. The median L/W and median W/P ratios were 0.54 and 0.48, 0.66 and 0.49, and 0.71 and 0.68, respectively, in GA, GB, and GC. The W/P ratio was significantly higher in GC compared with IFS-exposed animals (P=.001). The difference was significant between GC and GB (P=.008) but not between GC and GA. CONCLUSION: IFS induces coronary perivascular fibrosis that differs under treatment with corticosteroid.

Use of nitroglycerin in the active phase of tilt testing: is there a difference in elderly patients?

INTRODUCTION: The importance of tilt testing has been demonstrated in the evaluation of patients with syncope of unknown cause, and it is the gold standard technique for the diagnosis of neurocardiogenic syncope, particularly with the use of pharmacological provocative agents to improve diagnostic accuracy. Stimulation with sublingual nitroglycerin is generally well tolerated and increases test sensitivity, shortening the test duration; this also allows the test to be applied in elderly patients. OBJECTIVES: To evaluate, in a population referred for syncope of unknown etiology, the value of tilt testing with sublingual nitroglycerin and to compare the responses obtained in elderly and younger patients. METHODS: We studied 158 patients who underwent tilt testing using nitroglycerin as a provocative agent. We compared patients aged <65 years (Group A, n=74) and > or =65 years (Group B, n=84). Tilt testing was performed according to the Italian protocol, with continuous monitoring of the electrocardiogram and blood pressure (Task Force Monitor, CNSystems). Only patients who were asymptomatic in the passive phase of the test were included. The test was considered positive for neurocardiogenic response when symptoms were reproduced with bradycardia and/or hypotension; the responses were classified as cardioinhibitory, vasodepressor or mixed. A gradual and parallel decrease in blood pressure after nitroglycerin administration, followed by syncope, was considered an exaggerated response to nitrates. RESULTS: There were no differences in gender distribution between groups. Tilt testing was positive in 57% of group A and 51% of group B patients (p=NS), with an exaggerated response to nitrates in 11% and 16% respectively (p=NS). With regard to neurocardiogenic responses, vasodepression was more frequent in group B (53% vs. 24%; p=0.001), while a mixed response tended to be more frequent in group A (59% vs. 40%; p=0.07), with no significant difference in cardioinhibitory responses (17% in group A vs. 7% in group B; p=NS). CONCLUSIONS: In a population with syncope of unknown origin, tilt testing potentiated with nitroglycerin: a) makes a significant contribution to clarifying diagnosis and is of equal value in both elderly and younger patients; and b) is associated with a higher incidence of neurocardiogenic vasodepressor response in the elderly, although with a similar rate of exaggerated responses to nitrates.

Tilt test in elderly patients with syncope of unknown etiology: experience with pharmacological stimulation with nitroglycerin.

UNLABELLED: The importance of head-up tilt testing has been demonstrated in the evaluation of patients with unexplained syncope. In elderly patients, the prevalence of syncope increases, is associated with a worse outcome and frequently requires several complementary tests. OBJECTIVES: To evaluate the utility of head-up tilt testing with sublingual nitroglycerin as a provocative agent, in elderly patients with unexplained syncope. METHODS: We studied 46 consecutive patients aged >65 years (74 +/- 6 years, 56.5% female) with unexplained syncope. In 25 patients (54%), we found no cardiac anomaly. The remaining patients had hypertensive (14 patients) or ischemic (7 patients) heart disease. The protocol included carotid sinus massage in decubitus and after passive orthostatism. Tilt testing was performed with continuous electrocardiographic and blood pressure monitoring, at a 70 degrees tilt for 20 minutes. In the absence of syncope, we administered 500 mcg of nitroglycerin with an additional 20 minutes monitoring. The tilt test was considered positive when there was reproduction of symptoms associated with bradycardia and/or arterial hypotension (cardioinhibitory, vasodepressor or mixed response). We considered orthostatic hypotension to be present when systolic blood pressure decreased by >20 mmHg or diastolic blood pressure decreased by >10 mmHg during the first 3 minutes after orthostatism; patients with symptoms associated with a progressive and parallel decrease of systolic and diastolic blood pressure during passive tilt testing were considered to have a dysautonomic profile; patients with symptoms and a gradual decrease of blood pressure after nitroglycerin were considered to have an exaggerated response to nitrates. RESULTS: Symptoms were reproduced in 34 patients (73.9%): 19.6% during passive tilting (neurocardiogenic vasodepressor response--3 patients, carotid sinus hypersensitivity--1 patient, orthostatic hypotension--1 patient, dysautonomic profile--4 patients) and 54.3% after nitroglycerin (neurocardiogenic vasodepressor response--12 patients, mixed--5 patients, cardioinhibitory--2 patients and exaggerated response to nitrates--6 patients). Syncope was neurocardiogenic in 47.8% (passive test--13.6%, after nitroglycerin--86.4%). There was an exaggerated response to nitrates in 16.2% of the patients given nitroglycerin. There were no complications during the test. CONCLUSIONS: Tilt testing in the elderly with syncope of unknown origin: (1) helps differential diagnosis in etiological study of the syncope and (2) when potentiated by nitroglycerin, it produces a significant increase in positive responses, and identifies a considerable number of patients with an exaggerated response to nitrates.

Long-term clinical outcome in patients with severe left ventricular dysfunction and an implantable cardioverter-defibrillator after ventricular tachyarrhythmias.

UNLABELLED: Left ventricular ejection fraction (LVEF) is accepted as an important prognostic marker in patients (pts) with implantable cardioverter-defibrillators (ICD). The impact of this therapeutic approach in the survival of pts with life-threatening arrhythmias and severe left ventricular dysfunction remains a matter of discussion. OBJECTIVE: To evaluate the long-term clinical implications of severe left ventricular dysfunction in pts with an ICD implanted for secondary prevention of sudden cardiac death (SD). METHODS: Out of 70 pts undergoing ICD implantation in our institution over four consecutive years, we studied 24 pts with LVEF <35% and a post-ICD follow-up of >12 months (87.5% male; age 62.79 years). The index arrhythmia was ventricular tachycardia in 19 cases and SD with ventricular fibrillation in 5 cases. The underlying disease was ischemic cardiomyopathy (n=19), dilated cardiomyopathy (n=4) and hypertensive heart disease (n=1). Mean LVEF at the time of implant was 25 +/- 7% (between 11% and 34%; NYHA class II/III in 83.3%). A du chamber system was implanted in 5 cases, and an ICD plus cardiac resynchronization pacing in 2 cases. There was no perioperative mortality. At the time of discharge, 71.2% of the pts were taking amiodarone and 66.7 % beta-blockers. During a 38 +/- 16-month follow-up (4 appointments/year), we analyzed the following parameters: rehospitalization for cardiovascular cause, appropriate ICD shocks, inappropriate detections/therapy, nonfatal major arrhythmic events (arrhythmic storm, therapeutic exhaustion, recurrent ventricular tachycardia), cardiac mortality, SD and total mortality. RESULTS: Forty-five readmissions (1.9 +/- 2.3/pt) occurred in 14 pts (58%), 24.4% due to congestive heart failure. Appropriate ICD shocks (without hospitalization) occurred in 62.5% of the pts, 16.6% had inappropriate therapy (50% because of increased heart rate due to atrial fibrillation) and 37.5% suffered nonfatal major arrhythmic events. Death due to SD was 4.2%, cardiac mortality 12.5% and total mortality 25%. CONCLUSIONS: Severe left ventricular dysfunction is common in ICD pts. During long-term follow-up, the majority of these pts receive appropriate ICD shocks, which emphasizes the importance of SD prevention in this population. The frequent documentation of supraventricular arrhythmias (causing inappropriate ICD therapy) and nonfatal major arrhythmic events also reflects the presence of a worse arrhythmic substrate in this subgroup. Despite the poor initial prognosis associated with ventricular tachyarrhythmias in pts with severe left ventricular dysfunction, ICD therapy may contribute to a better long-term clinical outcome.

Non-toxigenic pattern II and III Bacteroides fragilis strains: coexistence in the same host.

Diarrhoeic stool samples from 334 0-5-year-old children were analysed with respect to the incidence of Bacteroides fragilis as well as other enteropathogens. B. fragilis was recovered in 9.3% (31/334) of the samples, and 79 strains were examined for the presence of the bft gene or the BfPAI flanking region using polymerase chain reaction assays. No enterotoxigenic B. fragilis strains were detected. In 29% (9/31) of the samples the coexistence of both II and III non-toxigenic B. fragilis (NTBF) patterns could be seen. In 51.6% (16/31) of the samples there existed a pattern II NTBF only, and in 19.4% (6/31) only pattern III could be detected. Strains from the same patient representing different patterns were submitted to pulsed-field gel electrophoresis assays. Fingerprints obtained by this technique showed that there was strong heterogeneity among strains from different individuals. However, different patterns from the same individual shared 100% similarity.

Immunohistochemical evaluation of cardiac connexin43 in rats exposed to low-frequency noise.

INTRODUCTION: Low-frequency noise (LFN) leads to an abnormal proliferation of collagen and development of tissue fibrosis. It has been shown that myocardial fibrosis in association with gap junction remodeling occurs in several cardiac diseases and can be implicated in the development of ventricular tachyarrhythmias. We previously reported a strong development of myocardial fibrosis induced by LFN in rats but it is not known whether LFN induces any modification on cardiac connexin43 (Cx43). OBJECTIVES: The aim of this study was to evaluate modifications on cardiac Cx43 induced by LFN in Wistar rats. METHODS: Two groups of rats were considered: A LFN-exposed group with 10 rats submitted continuously to LFN during 3 months and a control group with 8 rats. The hearts were sectioned from the ventricular apex to the atria and the mid-ventricular fragment was selected. The immunohistochemical evaluation of Cx43 was performed using the polyclonal antibody connexin-43m diluted 1:1000 overnight at 4°C. Quantifications of Cx43 and muscle were performed with the image J software and the ratio Cx43/muscle was analyzed in the left ventricle, interventricular septum and right ventricle. RESULTS: The ratio Cx43/muscle was significantly reduced in LFN-exposed rats (p=0.001). The mean value decreased 46.2%, 22.2% and 55.6% respectively in the left ventricle (p=0.008), interventricular septum (p=0.301) and right ventricle (p=0.004). CONCLUSIONS: LFN induces modifications on cardiac Cx43 in rats. The Cx43 reduction observed in our study suggests that LFN may induce an arrhythmogenic substrate and opens a new investigational area concerning the effects of LFN on the heart.

Effects of low-frequency noise on cardiac collagen and cardiomyocyte ultrastructure: an immunohistochemical and electron microscopy study.

INTRODUCTION: Low-frequency noise (LFN) leads to the development of tissue fibrosis. We previously reported the development of myocardial and perivascular fibrosis and a reduction of cardiac connexin43 in rats, but data is lacking concerning the affected type of collagen as well as the ultrastructural myocardial modifications. OBJECTIVES: The aim of this study was to quantify cardiac collagens I and III and to evaluate myocardial ultrastructural changes in Wistar rats exposed to LFN. METHODS: Two groups of rats were considered: A LFN-exposed group with 8 rats continuously submitted to LFN during 3 months and a control group with 8 rats. The hearts were sectioned and the mid-ventricular fragment was selected. After immunohistochemical evaluation, quantification of the collagens and muscle were performed using the image J software in the left ventricle, interventricular septum and right ventricle and the collagen I/muscle and collagen III/muscle ratios were calculated. Transmission electron microscopy (TEM) was used to analyze mid-ventricular samples taken from each group. RESULTS: The collagen I/muscle and collagen III/muscle ratios increased in totum respectively 80% (p<0.001) and 57.4% (p<0.05) in LFN-exposed rats. TEM showed interstitial collagen deposits and changes in mitochondria and intercalated discs of the cardiomyocytes in LFN-exposed animals. CONCLUSIONS: LFN increases collagen I and III in the extracellular matrix and induces ultrastructural alterations in the cardiomyocytes. These new morphological data open new and promising paths for further experimental and clinical research regarding the cardiac effects of low-frequency noise.

[INR telemonitoring: efficacy and safety of a telemonitoring program in 453 patients]. / telemonitorização de INR: eficácia e segurança de um sistema de avaliação em 453 doentes.

INTRODUCTION: The INR analyses of patients taking oral anticoagulants brings great burden to healthcare professionals, overspending founds from the National Health Service (NHS) and loss of quality of life of patients who are forced to frequent hospital visits. It should not be surprising that the technology is at the forefront of health care nowadays and some projects have been developed in the area of anticoagulation for INR self-monitoring by telephone, mobile phone or internet. The aim of this study was to assess the efficacy and safety of an INR telemonitoring system that was implemented in our hospital in 2006. METHODS: A prospective, observational study of 453 patients who were included in this telemonitoring system from 2006 until late November 2010. The communication between patients and health professionals was done via mobile phone messages in a standardized and codified system that included information about maintenance or modification of therapy and the date of the next evaluation. When necessary the patient could send a request for help through a code for that purpose. In the studied population the following parameters were evaluated: withdrawal of the telemonitoring project, need for change of anticoagulant dose, requests for clarification by the patient, hospitalization for bleeding complications and INR > 10. RESULTS: In our study population 53% were female, mean age = 57 +/- 16 years. The percentage of INR values within the therapeutic range was 83%. There were no dropouts of the telemonitoring project. The percentage of patients with major and minor bleeding complications during follow-up was 0.4% and 0.2% respectively. CONCLUSIONS: The telemonitoring system proves safe and effective remote monitoring of INR analysis, allowing efficient monitoring of INR with low prevalence of major or minor bleeding.