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

Muscle metaboreflex and cerebral blood flow regulation in humans:implications for exercise with blood flow restriction

We investigated the effect of activating metabolically sensitive skeletal muscle afferents (muscle metaboreflex) on cerebral blood flow and the potentially confounding influence of concomitant changes in the partial pressure of arterial carbon dioxide. Eleven healthy males (25 ± 4 yr) performed submaximal leg cycling exercise on a semirecumbent cycle ergometer (heart rate: ∼120 beats/min), and assessments were made of the partial pressure of end-tidal carbon dioxide (PetCO2), internal carotid artery blood flow (ICAQ) and conductance (ICACVC), and middle cerebral artery mean blood velocity (MCAvm) and conductance index (MCACVCi).The muscle metaboreflex was activated during cycling with leg blood flow restriction (BFR) or isolated with postexercise ischemia (PEI). In separate trials, PetCO2was either permitted to fluctuate spontaneously (control trial) or was clamped at 1 mmHg above resting levels (PetCO2clamp trial). In the control trial, leg cycling with BFR decreased PetCO2(Δ−4.8 ± 0.9 mmHg vs. leg cycling exercise) secondary to hyperventilation, while ICAQ, ICACVC, and MCAvmwere unchanged and MCACVCidecreased. However, in the PetCO2clamp trial, leg cycling with BFR increased both MCAvm(Δ5.9 ± 1.4 cm/s) and ICAQ(Δ20.0 ± 7.8 ml/min) and attenuated the decrease in MCACVCi, while ICACVCwas unchanged. In the control trial, PEI decreased PetCO2(Δ−7.0 ± 1.3 mmHg vs. rest), MCAvmand MCACVCi, whereas ICAQand ICACVCwere unchanged. In contrast, in the PetCO2clamp trial both ICAQ(Δ18.5 ± 11.9 ml/min) and MCAvm(Δ8.8 ± 2.0 cm/s) were elevated, while ICACVCand MCACVCiwere unchanged. In conclusion, when hyperventilation-related decreases in PetCO2are prevented the activation of metabolically sensitive skeletal muscle afferent fibers increases cerebral blood flow.</jats:p

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. </jats:p

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

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

Função muscular esquelética e composição corporal de pacientes com hipertireoidismo submetidos ao treinamento contra resistência Skeletal muscle performance and body composition of patients with hyperthyroidism submitted to strength training

O hipertireoidismo está associado a uma fraqueza muscular generalizada que é parte da manifestação clínica inicial de cerca de 80% dos pacientes. A recuperação da performance muscular esquelética durante o tratamento do hipertireoidismo depende tanto do aumento da massa muscular quanto da melhoria da função intrínseca da musculatura esquelética. Por outro lado, o treinamento contra resistência aumenta a força e a endurance muscular em diferentes grupos de indivíduos. O objetivo do presente trabalho foi avaliar o efeito deste tipo de treinamento sobre a recuperação da função muscular esquelética de pacientes portadores de hipertireoidismo. Os pacientes, atendidos no ambulatório de endocrinologia, diagnosticados clínica e laboratorialmente com doença de Graves, foram submetidos, antes do tratamento e quatro meses após, a medidas antropométricas e testes de força máxima e endurance musculares (sustentando 30% da carga máxima) de quatro movimentos [handgrip esquerdo (HE) e direito (HD), legpress (LEG), flexão plantar de tornozelo (FPT) e supino reto (SR)]. Após a avaliação inicial, os pacientes foram divididos em dois grupos: 1) controle (GC - tratamento medicamentoso) e 2) treinamento (GT - acrescentado treinamento contra resistência individualizado 2X/semana). Os resultados (GC, n = 3; GT, n = 4; todas do sexo feminino) mostram: <img src="/img/revistas/rbme/v7n1/a04tab01.gif"> Os autores concluem que o treinamento contra resistência parece favorecer aumento da massa e da performance muscular esquelética em pacientes com hipertireoidismo.<br>Hyperthyroidism is associated with a general muscle weakness, which is part of the initial clinical manifestation of about 80% of patients. The recovery of skeletal muscle performance during hyperthyroidism treatment depends on both greater muscle mass and improved muscle function. Strength training is an effective method to improve muscle strength and endurance. The purpose of this study was to evaluate the effect of this type of training on the recovery of the skeletal muscle function of patients with hyperthyroidism. Patients referred to the Endocrinology Out-Patient Clinic with clinical diagnosis and laboratory confirmation of Grave's disease were submitted, before the treatment and 4 months later, to anthropometric measurements and determination of maximal static strength and endurance (sustaining 30% of the maximal force) of four movements [left handgrip (LH), right handgrip (RH), legpress (LEG), ankle plantar flexion (APF) and supine benchpress (SP)]. After the first evaluation, the patients were divided into two groups: 1) control (CG- drug treatment) and 2) training (TG- added individualized strength training twice a week). Results (CG, n=3; TG, n=4; all women) showed: <img src="/img/revistas/rbme/v7n1/a04tab02.gif"> The authors concluded that strength training seems to favor an increase in skeletal muscle mass and performance in patients with hyperthyroidism

Reply to comments by Sanjay K. Mukhopadhyay, Sucharita Pal, J. P. Shrivastava on the paper by Sial et al. (2016) Mercury enrichments and Hg isotopes in Cretaceous–Paleogene boundary successions: Links to volcanism and palaeoenvironmental impacts. Cretaceous Research 66, 60–81

One key to address the issue of the location of the K/Pg boundary at the Um Sohryngkew sections to look at Ccarb, Corg, Hg/TOC, Mo/Al chemostratigraphies, alongside Hg isotopes, in previous studied K/Pg sections in the Meghalaya area, and compare them with same type of data reported in Sial et al. (2016). The possibility of diachronic deposition cannot be totally discarded, and the K/Pg boundary could have been recorded in the Langpar Formation at one site and in the contact between the Mahadeo and Langpar formations in another. A tectonic-induced doubling of the sequence is also possible as the Meghalaya area, within the Shillong plateau, has been linked to a number of kinematic changes, including pop-up tectonics, since the Cretaceous.Fil: Sial, Alcídes Nóbrega. Universidade Federal de Pernambuco; BrasilFil: Chen, Jiubin. Chinese Academy of Sciences; República de ChinaFil: Lacerda, L. D.. Universidade Estadual do Ceará; BrasilFil: Frei, Robert. Universidad de Copenhagen; Dinamarca. Nordic Center for Earth Evolution; DinamarcaFil: Tewari, Vinod Chandra. Sikkim University; IndiaFil: Pandit, Manoj K.. University of Rajasthan; IndiaFil: Gaucher, Claudio. Universidad de la República. Facultad de Ciencias; UruguayFil: Ferreira, Valderéz Pinto P.. Universidade Federal de Pernambuco; BrasilFil: Cirilli, Simonetta. Università di Perugia; ItaliaFil: Peralta, Silvio Heriberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; ArgentinaFil: Korte, Christoph. Universidad de Copenhagen; Dinamarca. Nordic Center for Earth Evolution; DinamarcaFil: Barbosa, José Antonio. Universidade Federal de Pernambuco; BrasilFil: Pereira, Natan. Universidade Federal da Bahia; Brasi