Prolonged heart rate recovery time after 6-minute walk test is an independent risk factor for cardiac events in heart failure: a prospective cohort study

OBJECTIVES: To determine whether the time for peak exercise heart rate to return to resting heart rate after the 6-minute walk test (6MWT) can predict cardiac events in patients with heart failure (HF) within 2 years. DESIGN: Prospective cohort study. SETTING: HF outpatient facility at a tertiary teaching hospital. PARTICIPANTS: Seventy-six patients with HF, New York Heart Association functional classification II and III, and left ventricular ejection fraction <50% MAIN OUTCOME MEASURES: Patients used a heart rate monitor to measure the time for peak exercise heart rate to return to resting heart rate after the 6MWT. Data were analysed using Polar Pro-Trainer 5 software (Kempele, Finland). Patients were followed for >2 years for cardiac events (hospitalisations and death). RESULTS: Thirty-four patients had cardiac events during the 2-year follow-up period. There was a significant difference in time to return to resting heart rate between the groups with and without cardiac events {with 3.6 [standard deviation (SD) A] vs without 2.8 (SD B) minutes; mean difference C; 95% confidence interval (CI) of the difference D to E; P=0.003}. No significant differences between patients with and without cardiac events were found for mean walking distance, mean heart rate recovery at 1 minute and mean heart rate recovery at 2 minutes. The receiver operating curve discriminated between patients with and without cardiac events (área under the curve 0.71, 95% CI 0.61 to 0.81; P< 0.001). Using logistic regression analysis, prolonged time to return to resting heart rate (≥3 minutes) independently increased the risk for cardiac events 6.9-fold (95% CI 2.34 to 20.12; P< 0.001). The Kaplan­Meier curve showed more cardiac events in patients with prolonged time to return to resting heart rate (P=0.028). CONCLUSIONS: Prolonged time to return to resting heart rate (≥3 minutes) after the 6MWT was an independent predictor of cardiac events in patients with HF.

Prolonged heart rate recovery time after 6-minute walk test is an independent risk factor for cardiac events in heart failure: A prospective cohort study.

OBJECTIVES: To determine whether the time for peak exercise heart rate to return to resting heart rate after the 6-minute walk test (6MWT) can predict cardiac events in patients with heart failure (HF) within 2 years. DESIGN: Prospective cohort study. SETTING: HF outpatient facility at a tertiary teaching hospital. PARTICIPANTS: Seventy-six patients with HF, New York Heart Association functional classification II and III, and left ventricular ejection fraction <50%. MAIN OUTCOME MEASURES: Patients used a heart rate monitor to measure the time for peak exercise heart rate to return to resting heart rate after the 6MWT. Data were analysed using Polar Pro-Trainer 5 software (Kempele, Finland). Patients were followed for >2 years for cardiac events (hospitalisations and death). RESULTS: Thirty-four patients had cardiac events during the 2-year follow-up period. However, there was a significant difference in the time to return to resting heart rate between the groups with and without cardiac events {with 3.6 (SD 1.1) vs without 2.8 (SD 1.1) minutes; mean difference of 0.79 (95% confidence interval (CI) of the difference 0.28 to 1.28; P=0.003}. No significant differences between patients with and without cardiac events were found for mean walking distance, mean heart rate recovery at 1minute and mean heart rate recovery at 2minutes. The receiver operating curve discriminated between patients with and without cardiac events (área under the curve 0.71, 95% CI 0.61 to 0.81; P<0.001). Using logistic regression analysis, prolonged time to return to resting heart rate (≥3minutes) independently increased the risk for cardiac events 6.9-fold (95% CI 2.34 to 20.12; P<0.001). The Kaplan-Meier curve showed more cardiac events in patients with prolonged time to return to resting heart rate (P=0.028). CONCLUSIONS: Prolonged time to return to resting heart rate (≥3minutes) after the 6MWT was an independent predictor of cardiac events in patients with HF.

Tempo de recuperação da frequência cardíaca como marcador prognóstico de eventos cardíacos / Heart rate recovery time as a prognostic marker of cardiac events

INTRODUÇÃO: O teste de caminhada de 6 minutos (TC6M) é um teste funcional amplamente utilizado em pacientes com insuficiência cardíaca crônica (IC). A distância percorrida no teste, bem como o delta de frequência cardíaca entre o repouso e a recuperação no 1° minuto (HRR1) e o delta de frequência cardíaca entre o repouso e a recuperação no 2° minuto (HRR2) têm sido propostos como marcadores prognósticos de eventos cardíacos em pacientes com IC. Nós hipotetizamos que a variação do tempo em minutos (denominado THRR) entre o pico da frequência cardíaca e o retorno à frequência cardíaca no repouso possa ser um marcador simples e de fácil obtenção no contexto clínico para estimar eventos cardíacos em pacientes com IC. OBJETIVOS: Nós investigamos se o THRR pode ser usado para estimar hospitalizações e morte ao longo de 2 anos de acompanhamento em pacientes com IC. MÉTODOS: Setenta e seis pacientes (média de idade 57 anos, NYHA II e III, IMC 25.5kg/m2, média FEVE de 33%) foram incluídos nesse estudo e divididos em Com eventos e Sem eventos. RESULTADOS: Trinta e quatro pacientes do grupo Com eventos e 42 pacientes do grupo Sem eventos tiveram, respectivamente as seguintes médias: THRR= 3.6 vs 2.8 min (p=0,003), distância percorrida= 463 vs 465 metros (p=0,930), HRR1=12 bpm para ambos grupos (p=0,952) e HRR2= 23 vs 22 bpm (p=0,723). A área sob a curva ROC para discriminar eventos e não eventos foi de 0,70 (IC95%: 0,58-0,82 e p=0,001). Usando a análise de regressão logística, o THRR ≥ 3 minutos dobrou o risco para eventos cardíacos (p=0,003). CONCLUSÃO: A variação de tempo entre o pico do exercício no TC6M e a recuperação da frequência cardíaca de repouso ≥ 3 minutos é um eficiente marcador clínico preditor de hospitalizações e morte em 2 anos para pacientes com IC. (AU)

Subchronic effects of nasally instilled diesel exhaust particulates on the nasal and airway epithelia in mice.

Diesel exhaust is the major source of ultrafine particles released during traffic-related pollution. Subjects with chronic respiratory diseases are at greater risk for exacerbations during exposure to air pollution. This study evaluated the effects of subchronic exposure to a low-dose of diesel exhaust particles (DEP). Sixty male BALB/c mice were divided into two groups: (a) Saline: nasal instillation of saline (n = 30); and (b) DEP: nasal instillation of 30 microg of DEP/10 microl of saline (n = 30). Nasal instillations were performed 5 days a week, over 30 and 60 days. Animals were anesthetized with pentobarbital sodium (50 mg/kg intraperitoneal [i.p.]) and sacrificed by exsanguination. Bronchoalveolar lavage (BAL) fluid was performed to evaluate the inflammatory cell count and the concentrations of the interleukin (IL)-4, IL-10, and IL-13 by enzyme-linked immunosorbent assay (ELISA). The gene expression of oligomeric mucus/gel-forming (Muc5ac) was evaluated by real-time polymerase chain reaction (PCR). Histological analysis in the nasal septum and bronchioles was used to evaluate the bronchial and nasal epithelium thickness as well as the acidic and neutral nasal mucus content. The saline group (30 and 60 days) did not show any changes in any of the parameters. However, the instillation of DEP over 60 days increased the expression of Muc5ac in the lungs and the acid mucus content in the nose compared with the 30-day treatment, and it increased the total leukocytes in the BAL and the nasal epithelium thickness compared with saline for 60 days. Cytokines concentrations in the BAL were detectable, with no differences among the groups. Our data suggest that a low-dose of DEP over 60 days induces respiratory tract inflammation.

Effects of acute hypovolaemia by furosemide on tracheal transepithelial potential difference and mucus in dogs.

Furosemide is a potent diuretic that affects water transfer across the respiratory epithelium, which is closely related to the transepithelial potential difference (PD). Water is a critical factor that determines mucus transport; an important lung defence mechanism that removes particles and microorganisms from the respiratory system. The aim of the present study was to investigate the acute effects of furosemide and hypovolaemia on tracheal PD and mucus properties. A total of 36 male mixed-breed dogs were submitted to anaesthesia, mechanical ventilation and haemodynamic monitoring. They were randomly assigned to three groups consisting of: a control group, a furosemide (40 mg i.v.) + hypovolaemia group, and a furosemide (40 mg i.v.) + volume replacement group. Tracheal PD and mucus samples were collected at time 0, 1 and 2 h after intervention. Mucus properties were analysed by means of a magnetic microrheometer and in vitro mucociliary transportability on the frog palate. Compared to controls, furosemide decreased PD to intermediate values, and only significantly when associated with hypovolaemia (-13+/-5 and -8+/-2 mV, time 0 and 2 h, respectively). In addition to the direct effect of furosemide, these results indicate that hypovolaemia also affects ion transport in the tracheal membrane. Furosemide and hypovolemia have no acute effects on respiratory mucus properties.

Effects of a heat and moisture exchanger and a heated humidifier on respiratory mucus in patients undergoing mechanical ventilation.

OBJECTIVE: To evaluate the effects of a heat and moisture exchanger and a heated humidifier on respiratory mucus and transportability by cilia and cough in patients undergoing invasive mechanical ventilation (up to 72 hrs). DESIGN: Prospective, randomized, clinical study. SETTING: General intensive care unit and university research laboratory. PATIENTS: A total of 32 consecutive patients with acute respiratory failure, who were intubated and mechanically ventilated in the intensive care unit setting, were enrolled in the study. INTERVENTIONS: Patients were randomly assigned to receive as a humidifying system a heat and moisture exchanger (HME) or heated humidified water (HHW) at the onset of mechanical ventilation (time 0). Respiratory mucus samples were collected by suction using a sterile technique at time 0, 24, 48, and 72 hrs of mechanical ventilation. MEASUREMENTS AND MAIN RESULTS: Eleven patients were excluded from this study because of either extubation or death before 72 hrs of mechanical ventilation, leaving 12 patients in the HME group and nine patients in the HHW group. Ventilatory variables including minute volume, mean airway pressure, positive end-expiratory pressure, Fio2, as well as Pao2/Fio2 ratio, fluid balance (last 6 hrs), furosemide, and inotrope administration (last 4 hrs) were recorded. In vitro mucus transportability by cilia was evaluated on the mucus-depleted frog palate model, and the results were expressed as the mucus transport rate. Cough clearance (an estimation of the interaction between the flow of air and the mucus lining the bronchial walls) was measured using a simulated cough machine, the results being expressed in millimeters. Mucus wettability was measured by the contact angle between a mucus sample drop and a flat glass surface. Mucus rheologic properties (mechanical impedance [log G*] and the ratio between viscosity and elasticity [tan delta]) were measured using a magnetic microrheometer at 1 and 100 cGy/sec deformation frequency. The two humidification groups were comparable in terms of the Acute Physiology and Chronic Health Evaluation II score, age, gender, ventilatory variables, fluid balance, use of inotropes, and furosemide. CONCLUSION: Ours results indicate that air humidification with either HME or HHW at 32 degrees C (89.6 degrees F) has similar effects on mucus rheologic properties, contact angle, and transportability by cilia in patients undergoing mechanical ventilation, except for transportability by cough, which diminished after 72 hrs of mechanical ventilation in the HME group (p = .0441).

[Pediatric heart surgery in a general hospital. Procedures and results in a 5 years' experience]. / Cirurgia cardíaca infantil em hospital geral. Procedimentos e resultados em 5 anos de experiência.

PURPOSE: To establish the routines for pediatric cardiac surgery in a general hospital, with a view to accurate diagnostic, a more precise intervention, a reduction of the risks and consequently an improvement of the results. METHODS: Three hundred and ninety surgeries were carried out in children with congenital heart disease. The method use highlighted noninvasive diagnosis, joint lodging, reduced period of hospitalization, care with the collection and preservation of blood, as well as the preference for fresh blood, techniques of monitoring, anesthesia, cardiopulmonary bypass and myocardial protection, concern with aesthetic incision for female patients and postoperative critical care. RESULTS: A high rate of early extubation was observed, with a significant reduction of the pulmonary complications resulting from prolonged mechanical ventilation. Low haemodynamic instability, arrhythmia and postoperative bleeding rates were uncommon. The low mortality rate and the average hospitalization period confirmed the good results. CONCLUSION: With the establishment of routines for pediatric cardiac surgery, we observed a progressive improvement of the results, with low rates of morbidity and mortality in a general hospital.