Benefits of pharmacological and electrical cholinergic stimulation in hypertension and heart failure.

Systemic arterial hypertension and heart failure are cardiovascular diseases that affect millions of individuals worldwide. They are characterized by a change in the autonomic nervous system balance, highlighted by an increase in sympathetic activity associated with a decrease in parasympathetic activity. Most therapeutic approaches seek to treat these diseases by medications that attenuate sympathetic activity. However, there is a growing number of studies demonstrating that the improvement of parasympathetic function, by means of pharmacological or electrical stimulation, can be an effective tool for the treatment of these cardiovascular diseases. Therefore, this review aims to describe the advances reported by experimental and clinical studies that addressed the potential of cholinergic stimulation to prevent autonomic and cardiovascular imbalance in hypertension and heart failure. Overall, the published data reviewed demonstrate that the use of central or peripheral acetylcholinesterase inhibitors is efficient to improve the autonomic imbalance and hemodynamic changes observed in heart failure and hypertension. Of note, the baroreflex and the vagus nerve activation have been shown to be safe and effective approaches to be used as an alternative treatment for these cardiovascular diseases. In conclusion, pharmacological and electrical stimulation of the parasympathetic nervous system has the potential to be used as a therapeutic tool for the treatment of hypertension and heart failure, deserving to be more explored in the clinical setting.

Arginine and aerobic training prevent endothelial and metabolic alterations in rats at high risk for the development of the metabolic syndrome.

Endothelial function is a key mechanism in the development of CVD. Arginine and exercise are important non-pharmacological strategies for mitigating the impact of metabolic changes in the metabolic syndrome, but the effect of their combined administration is unknown. Thus, the aim of this study was to investigate the isolated and combined effects of aerobic training and arginine supplementation on metabolic variables and vascular reactivity in rats at high risk for developing the metabolic syndrome. Wistar rats were divided into two groups: control and fructose (F - water with 10 % fructose). After 2 weeks, the F group was divided into four groups: F, fructose+arginine (FA, 880 mg/kg per d of l-arginine), fructose+training (FT) and fructose+arginine+training (FTA); treatments lasted for 8 weeks, and no difference was observed in body mass gain. Arginine did not improve the body protein content, and both the FA and FT groups show a reversal of the increase in adipose tissue. Insulin increase was prevented by training and arginine, without additive effect, and the increase in serum TAG was prevented only by training. The F group showed impaired endothelium-dependent vasodilation and hyperreactivity to phenylephrine, but arginine and training were capable of preventing these effects, even separately. Higher nitric oxide level was observed in the FA and FT groups, and no potentiating effect was detected. Thus, only training was able to prevent the increase in TAG and improve the protein mass, and training and arginine exert similar effects on fat content, insulin and endothelial function, but these effects are not additive.

Effects of face cooling on pulse waveform and sympathetic activity in hypertensive subjects.

Adverse cardiovascular events occur more frequently during cold weather. To test the hypothesis that cold exposure would lead to increased sympathetic activity and impaired hemodynamic control, we measured muscle sympathetic nerve activity and hemodynamic parameters in nine men with hypertension before and during trigeminal stimulation and facial cooling. The procedure increased blood pressure (p < 0.01), aortic hemodynamic parameters (p < 0.01), and muscle sympathetic nerve activity (p < 0.05). These results suggest that sympathetic activation during cold exposure in hypertensive subjects may increase the risk of cardiovascular events during cold weather.

Diving and exercise: the interaction of trigeminal receptors and muscle metaboreceptors on muscle sympathetic nerve activity in humans.

Swimming involves muscular activity and submersion, creating a conflict of autonomic reflexes elicited by the trigeminal receptors and skeletal muscle afferents. We sought to determine the autonomic cardiovascular responses to separate and concurrent stimulation of the trigeminal cutaneous receptors and metabolically sensitive skeletal muscle afferents (muscle metaboreflex). In eight healthy men (30 ± 2 yr) muscle sympathetic nerve activity (MSNA; microneurography), mean arterial pressure (MAP; Finometer), femoral artery blood flow (duplex Doppler ultrasonography), and femoral vascular conductance (femoral artery blood flow/MAP) were assessed during the following three experimental conditions: 1) facial cooling (trigeminal nerve stimulation), 2) postexercise ischemia (PEI; muscle metaboreflex activation) following isometric handgrip, and 3) trigeminal nerve stimulation with concurrent PEI. Trigeminal nerve stimulation produced significant increases in MSNA total activity (Δ347 ± 167%) and MAP (Δ21 ± 5%) and a reduction in femoral artery vascular conductance (Δ-17 ± 9%). PEI also evoked significant increases in MSNA total activity (Δ234 ± 83%) and MAP (Δ36 ± 4%) and a slight nonsignificant reduction in femoral artery vascular conductance (Δ-9 ± 12%). Trigeminal nerve stimulation with concurrent PEI evoked changes in MSNA total activity (Δ341 ± 96%), MAP (Δ39 ± 4%), and femoral artery vascular conductance (Δ-20 ± 9%) that were similar to those evoked by either separate trigeminal nerve stimulation or separate PEI. Thus, excitatory inputs from the trigeminal nerve and metabolically sensitive skeletal muscle afferents do not summate algebraically in eliciting a MSNA and cardiovascular response but rather exhibit synaptic occlusion, suggesting a high degree of convergent inputs on output neurons.

Heart rate recovery in the first minute at the six-minute walk test in patients with heart failure.

BACKGROUND: Heart rate recovery at one minute of rest (HRR1) is a predictor of mortality in heart failure (HF), but its prognosis has not been assessed at six-minute walk test (6MWT) in these patients. OBJECTIVE: This study aimed to determine the HRR1 at 6MWT in patients with HF and its correlation with six-minute walk distance (6MWD). METHODS: Cross-sectional, controlled protocol with 161 individuals, 126 patients with stable systolic HF, allocated into 2 groups (G1 and G2) receiving or not ß-blocker and 35 volunteers in control group (G3) had HRR1 recorded at the 6MWT. RESULTS: HRR1 and 6MWD were significantly different in the 3 groups. Mean values of HRR1 and 6MWD were: HRR1 = 12 ± 14 beat/min G1; 18 ± 16 beat/min G2 and 21 ± 13 beat/min G3; 6MWD = 423 ± 102 m G1; 396 ± 101 m G2 and 484 ± 96 m G3 (p < 0.05). Results showed a correlation between HRR1 and 6MWD in G1(r = 0.3; p = 0.04) and in G3(r = 0.4; p= 0.03), but not in G2 (r= 0.12; p= 0.48). CONCLUSION: HRR1 response was attenuated in patients using ßB and showed correlation with 6MWD, reflecting better exercise tolerance. HRR1 after 6MWT seems to represent an alternative when treadmill tests could not be tolerated.

Acute effects of continuous positive air way pressure on pulse pressure in chronic heart failure.

BACKGROUND: Patients with heart failure (HF) have left ventricular dysfunction and reduced mean arterial pressure (MAP). Increased adrenergic drive causes vasoconstriction and vessel resistance maintaining MAP, while increasing peripheral vascular resistance and conduit vessel stiffness. Increased pulse pressure (PP) reflects a complex interaction of the heart with the arterial and venous systems. Increased PP is an important risk marker in patients with chronic HF (CHF). Non-invasive ventilation (NIV) has been used for acute decompensated HF, to improve congestion and ventilation through both respiratory and hemodynamic effects. However, none of these studies have reported the effect of NIV on PP. OBJECTIVE: The objective of this study was to determine the acute effects of NIV with CPAP on PP in outpatients with CHF. METHODS: Following a double-blind, randomized, cross-over, and placebo-controlled protocol, twenty three patients with CHF (17 males; 60±11 years; BMI 29±5 kg/cm2, NYHA class II, III) underwent CPAP via nasal mask for 30 min in a recumbent position. Mask pressure was 6 cmH2O, whereas placebo was fixed at 0-1 cmH2O. PP and other non invasive hemodynamics variables were assessed before, during and after placebo and CPAP mode. RESULTS: CPAP decreased resting heart rate (Pre: 72±9; vs. Post 5 min: 67±10 bpm; p<0.01) and MAP (CPAP: 87±11; vs. control 96±11 mmHg; p<0.05 post 5 min). CPAP decreased PP (CPAP: 47±20 pre to 38±19 mmHg post; vs. control: 42±12 mmHg, pre to 41±18 post p<0.05 post 5 min). CONCLUSION: NIV with CPAP decreased pulse pressure in patients with stable CHF. Future clinical trials should investigate whether this effect is associated with improved clinical outcome.

Efeito Agudo da Pressao Positiva Continua sobre a Pressao de Pulso na Insuficiencia Cardiaca Cronica / Acute Effects of Continuous Positive Air way Pressure on Pulse Pressure in Chronic Heart Failure

Fundamento: Pacientes com insuficiência cardíaca (IC) apresentam disfunção ventricular esquerda e redução da pressão arterial média (PAM). O aumento do estímulo adrenérgico causa vasoconstrição e resistência dos vasos, mantendo a PAM, enquanto aumenta a resistência vascular periférica e a rigidez dos vasos condutores. O aumento da pressão de pulso (PP) reflete a complexa interação do coração com os sistemas arteriais e venosos. O aumento da PP é um importante marcador de risco em pacientes com insuficiência cardíaca crônica (ICC). A ventilação não invasiva (VNI) tem sido utilizada para IC aguda descompensada para melhorar a congestão e a ventilação pelos efeitos respiratórios e hemodinâmicos. No entanto, nenhum desses estudos relatou o efeito da VNI na PP. Objetivo: O objetivo deste estudo foi determinar os efeitos agudos da VNI com CPAP (pressão positiva contínua nas vias aéreas) sobre a PP em pacientes ambulatoriais com ICC. Métodos: Seguindo um protocolo randomizado, duplo-cego, cruzado e controlado com placebo, 23 pacientes com ICC (17 homens, 60 ± 11 anos, IMC 29 ± 5 kg/cm2, classes II e III da NYHA) foram submetidos à CPAP via máscara nasal durante 30 minutos na posição reclinada. A pressão da máscara foi de 6 cmH2O, enquanto o placebo foi fixado em 0-1 cmH2O. PP e outras variáveis hemodinâmicas não invasivas foram avaliadas antes, durante e depois do placebo e do modo CPAP. Resultados: A CPAP diminuiu a frequência cardíaca de repouso (pré: 72 ± 9; pós 5 min: 67 ± 10 bpm , p < 0,01) e PAM (CPAP: 87 ± 11; controle 96 ± 11 mmHg , p < 0,05 pós 5 min). A CPAP diminuiu a PP (CPAP: 47 ± 20 pré para 38 ± 19 mmHg pós; controle: ...

Background: Patients with heart failure (HF) have left ventricular dysfunction and reduced mean arterial pressure (MAP). Increased adrenergic drive causes vasoconstriction and vessel resistance maintaining MAP, while increasing peripheral vascular resistance and conduit vessel stiffness. Increased pulse pressure (PP) reflects a complex interaction of the heart with the arterial and venous systems. Increased PP is an important risk marker in patients with chronic HF (CHF). Non-invasive ventilation (NIV) has been used for acute decompensated HF, to improve congestion and ventilation through both respiratory and hemodynamic effects. However, none of these studies have reported the effect of NIV on PP. Objective: The objective of this study was to determine the acute effects of NIV with CPAP on PP in outpatients with CHF. Methods: Following a double-blind, randomized, cross-over, and placebo-controlled protocol, twenty three patients with CHF (17 males; 60 ± 11 years; BMI 29 ± 5 kg/cm2, NYHA class II, III) underwent CPAP via nasal mask for 30 min in a recumbent position. Mask pressure was 6 cmH2O, whereas placebo was fixed at 0-1 cmH2O. PP and other non invasive hemodynamics variables were assessed before, during and after placebo and CPAP mode. Results: CPAP decreased resting heart rate (Pre: 72 ± 9; vs. Post 5 min: 67 ± 10 bpm; p < 0.01) and MAP (CPAP: 87 ± 11; vs. control 96 ± 11 mmHg; p < 0.05 post 5 min). CPAP decreased PP (CPAP: 47 ± 20 pre to 38 ± 19 mmHg post; vs. control: 42 ± 12 mmHg, pre to 41 ± 18 post p < 0.05 post 5 min). Conclusion: NIV with CPAP decreased pulse pressure in patients with stable CHF. Future clinical trials should investigate whether this effect is associated with improved clinical outcome. .

Frequência Cardíaca de Recuperação no Primeiro Minuto no Teste de Caminhada de Seis Minutos em Pacientes com Insuficiência Cardíaca / Heart Rate Recovery in the First Minute at the Six-Minute Walk Test in Patients with Heart Failure

Fundamento: A frequência cardíaca de recuperação no primeiro minuto (FCR1) é um preditor de mortalidade na insuficiência cardíaca (IC), mas seu prognóstico não foi avaliado no teste de caminhada de seis minutos (TC6M) nesses pacientes. Objetivo: Esse estudo teve como objetivo determinar a FCR1 no TC6M em pacientes com IC e sua correlação com a distância percorrida em seis minutos (DP6M). Métodos: Protocolo controlado, transversal, com 161 indivíduos, 126 pacientes com IC sistólica estável, divididos em dois grupos (G1 e G2), que receberam ou não β-bloqueador e 35 voluntários no grupo controle (G3) que tiveram a FCR1 registrada no TC6M. Resultados: A FCR1 e a DP6M foram significativamente diferentes nos três grupos. Os valores médios de FCR1 e DP6M foram: FCR1 = 12 ± 14 bpm G1, 18 ± 16 bpm G2 e 21 ± 13 bpm G3; DP6M = 423 ± 102 m G1, G2 396 ± 101 m e 484 ± 96 m G3 (p < 0,05). Os resultados demonstraram uma correlação entre FCR1 e DP6M no G1 (r = 0,3, p = 0,04) e G3 (r = 0,4, p = 0,03), mas não em G2 (r = 0,12, p = 0,48). Conclusão: A resposta da FCR1 foi atenuada em pacientes em uso de βB e mostrou correlação com o TC6M, refletindo uma melhor tolerância ao exercício. A FCR1 após a DP6M parece representar uma alternativa quando os testes de esforço na esteira não são tolerados. .

Background: Heart rate recovery at one minute of rest (HRR1) is a predictor of mortality in heart failure (HF), but its prognosis has not been assessed at six-minute walk test (6MWT) in these patients. Objective: This study aimed to determine the HRR1 at 6MWT in patients with HF and its correlation with six-minute walk distance (6MWD). Methods: Cross-sectional, controlled protocol with 161 individuals, 126 patients with stable systolic HF, allocated into 2 groups (G1 and G2) receiving or not β-blocker and 35 volunteers in control group (G3) had HRR1 recorded at the 6MWT. Results: HRR1 and 6MWD were significantly different in the 3 groups. Mean values of HRR1 and 6MWD were: HRR1 = 12 ± 14 beat/min G1; 18 ± 16 beat/min G2 and 21 ± 13 beat/min G3; 6MWD = 423 ± 102 m G1; 396 ± 101m G2 and 484 ± 96 m G3 (p < 0.05). Results showed a correlation between HRR1 and 6MWD in G1(r = 0.3; p = 0.04) and in G3(r = 0.4; p= 0.03), but not in G2 (r= 0.12; p= 0.48). Conclusion: HRR1 response was attenuated in patients using βB and showed correlation with 6MWD, reflecting better exercise tolerance. HRR1 after 6MWT seems to represent an alternative when treadmill tests could not be tolerated. .

Sex differences in blood pressure responses to mental stress are abolished after a single bout of exercise: underlying hemodynamic mechanisms.

We aimed to investigate whether the pressor responses to mental stress (MS) are exaggerated in men due to heightened cardiac responses, before and after a bout of exercise. Fifteen men and 19 women underwent a protocol consisting of blood pressure (BP), cardiac output (CO) and forearm vascular assessments at baseline and during MS, and these measurements were performed before and 60 min after a bout of exercise. Before exercise, BP response was significantly augmented in men (Δ16 ± 2 mmHg) compared to women (Δ11 ± 1 mmHg). This BP response was accompanied by greater increases in CO in men and similar vascular responses between sexes. After exercise, BP and CO responses to MS were attenuated in men and, consequently, no sex differences were observed. Vascular responses were not affected by exercise. The mechanism underlying the lack of sex differences in BP response to MS after exercise was found to be a marked attenuation in CO in men only.

Cardiac I123-MIBG correlates better than ejection fraction with symptoms severity in systolic heart failure.

BACKGROUND: The association of autonomic activation, left ventricular ejection fraction (LVEF) and heart failure functional class is poorly understood. OBJECTIVE: Our aim was to correlate symptom severity with cardiac sympathetic activity, through iodine-123-metaiodobenzylguanidine (123I-MIBG) scintigraphy and with LVEF in systolic heart failure (HF) patients without previous beta-blocker treatment. METHODS: Thirty-one patients with systolic HF, class I to IV of the New York Heart Association (NYHA), without previous beta-blocker treatment, were enrolled and submitted to 123I-MIBG scintigraphy and to radionuclide ventriculography for LVEF determination. The early and delayed heart/mediastinum (H/M) ratio and the washout rate (WR) were performed. RESULTS: According with symptom severity, patients were divided into group A, 13 patients in NYHA class I/II, and group B, 18 patients in NYHA class III/IV. Compared with group B patients, group A had a significantly higher LVEF (25% ± 12% in group B vs. 32% ± 7% in group A, p = 0.04). Group B early and delayed H/M ratios were lower than group A ratios (early H/M 1.49 ± 0.15 vs. 1.64 ± 0.14, p = 0.02; delayed H/M 1.39 ± 0.13 vs. 1.58 ± 0.16, p = 0.001, respectively). WR was significantly higher in group B (36% ± 17% vs. 30% ± 12%, p= 0.04). The variable that showed the best correlation with NYHA class was the delayed H/M ratio (r= -0.585; p=0.001), adjusted for age and sex. CONCLUSION: This study showed that cardiac 123I-MIBG correlates better than ejection fraction with symptom severity in systolic heart failure patients without previous beta-blocker treatment.

O I123-MIBG cardíaco se correlaciona melhor do que a fração de ejeção com a gravidade dos sintomas na insuficiência cardíaca sistólica / Cardiac I123-MIBG correlates better than ejection fraction with symptoms severity in systolic heart failure

FUNDAMENTO: A associação da ativação autonômica, fração de ejeção do ventrículo esquerdo (FEVE) e classe funcional da insuficiência cardíaca é mal compreendida. Objetivo: Nosso objetivo foi correlacionar a gravidade dos sintomas com a atividade simpática cardíaca, através do uso de iodo-123-metaiodobenzilguanidina (123I-MIBG); e com FEVE em pacientes com insuficiência cardíaca (IC) sistólica sem tratamento prévio com betabloqueador. MÉTODOS: Trinta e um pacientes com IC sistólica, classe I a IV da New York Heart Association (NYHA), sem tratamento prévio com betabloqueador, foram inscritos e submetidos à cintilografia com 123I-MIBG e ventriculografia radioisotópica para determinação da FEVE. A relação precoce e tardia coração/mediastino (H/M) e a taxa de washout (WO) foram medidas. RESULTADOS: De acordo com a gravidade dos sintomas, os pacientes foram divididos em grupo A, com 13 pacientes em classe funcional NYHA I/II, e grupo B, com 18 pacientes em classe funcional NYHA III/ IV. Em comparação com os pacientes do grupo B, o grupo A apresentou uma FEVE significativamente maior (25% ± 12% para o grupo B vs. 32% ± 7% no grupo A, p = 0,04). As relações precoces e tardias H/M do Grupo B foram menores do que as do grupo A (H/M precoce 1,49 ± 0,15 vs. 1,64 ± 0,14, p = 0,02; H/M tardia 1,39 ± 0,13 vs. 1,58 ± 0,16, p = 0,001, respectivamente). A taxa de WO foi significativamente maior no grupo B (36% ± 17% vs. 30% ± 12%, p = 0,04). A variável que mostrou a melhor correlação com a NYHA foi a relação H/M tardia (r = -0,585, p = 0,001), ajustada para idade e sexo. CONCLUSÃO: Esse estudo mostrou que o 123I-MIBG cardíaco se correlaciona melhor do que a fração de ejeção com a gravidade dos sintomas em pacientes com insuficiência cardíaca sistólica sem tratamento prévio com beta-bloqueador.

BACKGROUND:The association of autonomic activation, left ventricular ejection fraction (LVEF) and heart failure functional class is poorly understood. OBJECTIVE: Our aim was to correlate symptom severity with cardiac sympathetic activity, through iodine-123-metaiodobenzylguanidine (123I-MIBG) scintigraphy and with LVEF in systolic heart failure (HF) patients without previous beta-blocker treatment. METHODS: Thirty-one patients with systolic HF, class I to IV of the New York Heart Association (NYHA), without previous beta-blocker treatment, were enrolled and submitted to 123I-MIBG scintigraphy and to radionuclide ventriculography for LVEF determination. The early and delayed heart/mediastinum (H/M) ratio and the washout rate (WR) were performed. RESULTS: According with symptom severity, patients were divided into group A, 13 patients in NYHA class I/II, and group B, 18 patients in NYHA class III/IV. Compared with group B patients, group A had a significantly higher LVEF (25% ± 12% in group B vs. 32% ± 7% in group A, p = 0.04). Group B early and delayed H/M ratios were lower than group A ratios (early H/M 1.49 ± 0.15 vs. 1.64 ± 0.14, p = 0.02; delayed H/M 1.39 ± 0.13 vs. 1.58 ± 0.16, p = 0.001, respectively). WR was significantly higher in group B (36% ± 17% vs. 30% ± 12%, p= 0.04). The variable that showed the best correlation with NYHA class was the delayed H/M ratio (r= -0.585; p=0.001), adjusted for age and sex. CONCLUSION: This study showed that cardiac 123I-MIBG correlates better than ejection fraction with symptom severity in systolic heart failure patients without previous beta-blocker treatment.

Risk of hypothermia in a new Olympic event: the 10-km marathon swim.

INTRODUCTION: There are no available data addressing the potential clinical risks of open-water swimming competitions. OBJECTIVE: Address the risks of hypothermia and hypoglycemia during a 10-km open-water swimming competition in order to alert physicians to the potential dangers of this recently-introduced Olympic event. METHODS: This was an observational cross-sectional study, conducted during a 10-km open-water event (water temperature 21 degrees C). The highest ranked elite open-water swimmers in Brazil (7 men, 5 women; ages 21+/-7 years old) were submitted to anthropometrical measurements on the day before competition. All but one athlete took maltodextrine ad libitum during the competition. Core temperature and capillary glycemia data were obtained before and immediately after the race. RESULTS: Most athletes (83%) finished the race with mild to moderate hypothermia (core temperature <35 degrees C). The body temperature drop was more pronounced in female athletes (4.2+/-0.7 degrees C vs. male: 2.7+/-0.8 degrees C; p=0.040). When data from the athlete who did not take maltodextrine was excluded, capillary glycemia increased among athletes (pre 86.6+/-8.9 mg/dL; post 105.5+/-26.9 mg/dL; p=0.014). Time to complete the race was inversely related to pre- competition body temperature in men (r=-0.802; p=0.030), while it was inversely correlated with the change in capillary glycemia in women (r=-0.898; p=0.038). CONCLUSION: Hypothermia may occur during open-water swimming events even in elite athletes competing in relatively warm water. Thus, core temperature must be a chief concern of any physician during an open-water swim event. Capillary glycemia may have positive effects on performance. Further studies that include more athletes in a controlled setting are warranted.

Noninvasive ventilation with continuous positive airway pressure acutely improves 6-minute walk distance in chronic heart failure.

BACKGROUND: Noninvasive ventilation with continuous positive airway pressure (CPAP) has been used in patients with chronic heart failure (CHF), although its effect on exercise tolerance in these patients is unknown. The aim of this study was to determine the effects of CPAP on exercise tolerance in outpatients with CHF. METHODS: Following a double-blind, randomized, crossover, and placebo-controlled protocol, 12 patients with CHF (8 male; 4 female; age 54 +/- 12 years; body mass index 27.3 +/- 1.8 kg/m2, New York Heart Association Class II, III) underwent CPAP via nasal mask for 30 minutes in a recumbent position. Mask pressure was 3 cm H2O for 10 minutes, followed by individual progression up to 4 to 6 cm H2O, whereas placebo was fixed 0 to 1 cm H2O. A 6-minute walk test was performed after placebo and CPAP. RESULTS: Continuous positive airway pressure decreased the resting heart rate (pre: 80 +/- 17 bpm; post: 71 +/- 15 bpm; P = .001) and mean arterial pressure (pre: 103 +/- 14 mm Hg; post: 97 +/- 13 mm Hg; P = .008). During exercise test, CPAP increased the distance covered (CPAP: 538 +/- 78 m; placebo: 479 +/- 83 m; P < .001) and the peak heart rate (CPAP: 98 +/- 17; placebo: 89 +/- 12 bpm; P = .049) but did not change the peak mean arterial pressure (P = .161). CONCLUSION: Noninvasive ventilation with CPAP increased exercise tolerance in patients with stable CHF. Future clinical trials should investigate whether this effect is associated with improved clinical outcome.

Risk of hypothermia in a new olympic event: the 10-km marathon swim

INTRODUCTION: There are no available data addressing the potential clinical risks of open-water swimming competitions. OBJECTIVE: Address the risks of hypothermia and hypoglycemia during a 10-km open-water swimming competition in order to alert physicians to the potential dangers of this recently-introduced Olympic event. METHODS: This was an observational cross-sectional study, conducted during a 10-km open-water event (water temperature 21ºC). The highest ranked elite open-water swimmers in Brazil (7 men, 5 women; ages 21±7 years old) were submitted to anthropometrical measurements on the day before competition. All but one athlete took maltodextrine ad libitum during the competition. Core temperature and capillary glycemia data were obtained before and immediately after the race. RESULTS: Most athletes (83 percent) finished the race with mild to moderate hypothermia (core temperature <35ºC). The body temperature drop was more pronounced in female athletes (4.2±0.7ºC vs. male: 2.7±0.8ºC; p=0.040). When data from the athlete who did not take maltodextrine was excluded, capillary glycemia increased among athletes (pre 86.6±8.9 mg/dL; post 105.5±26.9 mg/dL; p=0.014). Time to complete the race was inversely related to pre- competition body temperature in men (r=-0.802; p=0.030), while it was inversely correlated with the change in capillary glycemia in women (r=-0.898; p=0.038). CONCLUSION: Hypothermia may occur during open-water swimming events even in elite athletes competing in relatively warm water. Thus, core temperature must be a chief concern of any physician during an open-water swim event. Capillary glycemia may have positive effects on performance. Further studies that include more athletes in a controlled setting are warranted.

Coronary artery bypass surgery and longitudinal evaluation of the autonomic cardiovascular function.

INTRODUCTION: Imbalance in autonomic cardiovascular function increases the risk for sudden death in patients with coronary artery disease (CAD), but the time course of the impact of coronary artery bypass grafting (CABG) on autonomic function has been little studied. Thus, the purpose of the present study was to determine the effects of the CABG on the cardiovascular autonomic function. METHODS: Patients undergoing CABG (n = 13) and two matched control groups (patients with CAD who refused surgical treatment [n = 9], and healthy volunteers [n = 9]) underwent a prospective longitudinal study consisting of autonomic evaluation before and after (3, 6, 15, 30, 60, and 90 days) surgery, including measurement of heart rate variability (HRV), respiratory sinus arrhythmia (RSA), and Valsalva maneuver. RESULTS: After CABG there was a decrease in, and a later recovery of, (1) the HRV in the time domain and in the frequency domain, (2) RSA, and (3) Valsalva maneuver. CONCLUSIONS: CABG caused an impairment, reversible after 60 days, of cardiovascular autonomic function, with a maximal decrease on about the sixth day after surgery.

Exercise testing in hypertensive patients taking different angiotensin-converting enzyme inhibitors.

OBJECTIVE: To compare blood pressure response to dynamic exercise in hypertensive patients taking trandolapril or captopril. METHODS: We carried out a prospective, randomized, blinded study with 40 patients with primary hypertension and no other associated disease. The patients were divided into 2 groups (n=20), paired by age, sex, race, and body mass index, and underwent 2 symptom-limited exercise tests on a treadmill before and after 30 days of treatment with captopril (75 to 150 mg/day) or trandolapril (2 to 4 mg/day). RESULTS: The groups were similar prior to treatment (p<0.05), and both drugs reduced blood pressure at rest (p<0.001). During treatment, trandolapril caused a greater increase in functional capacity (+31%) than captopril (+17%; p=0.01) did, and provided better blood pressure control during exercise, observed as a reduction in the variation of systolic blood pressure/MET (trandolapril: 10.7 1.9 mmHg/U vs 7.4 1.2 mmHg/U, p=0.02; captopril: 9.1 1.4 mmHg/U vs 11.4 2.5 mmHg/U, p=0.35), a reduction in peak diastolic blood pressure (trandolapril: 116.8 3.1 mmHg vs 108.1 2.5 mmHg, p=0.003; captopril: 118.2 3.1 mmHg vs 115.8 3.3 mmHg, p=0.35), and a reduction in the interruption of the tests due to excessive elevation in blood pressure (trandolapril: 50% vs 15%, p=0.009; captopril: 50% vs 45%, p=0.32). CONCLUSION: Monotherapy with trandolapril is more effective than that with captopril to control blood pressure during exercise in hypertensive patients.

Teste de esforço em hipertensos em uso de diferentes inibidores da enzima conversora da angiotensina / Exercise testing in hypertensive patients taking different angiotensin-converting enzyme inhibitors

OBJECTIVE: To compare blood pressure response to dynamic exercise in hypertensive patients taking trandolapril or captopril. METHODS: We carried out a prospective, randomized, blinded study with 40 patients with primary hypertension and no other associated disease. The patients were divided into 2 groups (n=20), paired by age, sex, race, and body mass index, and underwent 2 symptom-limited exercise tests on a treadmill before and after 30 days of treatment with captopril (75 to 150 mg/day) or trandolapril (2 to 4 mg/day). RESULTS: The groups were similar prior to treatment (p<0.05), and both drugs reduced blood pressure at rest (p<0.001). During treatment, trandolapril caused a greater increase in functional capacity (+31 percent) than captopril (+17 percent; p=0.01) did, and provided better blood pressure control during exercise, observed as a reduction in the variation of systolic blood pressure/MET (trandolapril: 10.7±1.9 mmHg/U vs 7.4±1.2 mmHg/U, p=0.02; captopril: 9.1±1.4 mmHg/U vs 11.4±2.5 mmHg/U, p=0.35), a reduction in peak diastolic blood pressure (trandolapril: 116.8±3.1 mmHg vs 108.1±2.5 mmHg, p=0.003; captopril: 118.2±3.1 mmHg vs 115.8±3.3 mmHg, p=0.35), and a reduction in the interruption of the tests due to excessive elevation in blood pressure (trandolapril: 50 percent vs 15 percent, p=0.009; captopril: 50 percent vs 45 percent, p=0.32). CONCLUSION: Monotherapy with trandolapril is more effective than that with captopril to control blood pressure during exercise in hypertensive patients