Effect of Resistance Training on Blood Pressure and Autonomic Responses in Treated Hypertensives.

Trevizani, GA, Seixas, MB, Benchimol-Barbosa, PR, Vianna, JM, da Silva, LP, and Nadal, J. Effect of resistance training on blood pressure and autonomic responses in treated hypertensives. J Strength Cond Res 32(5): 1462-1470, 2018-This study evaluated the effect of resistance training (RT) on heart rate variability (HRV) and on blood pressure (BP) responses to acute and short-term exposure in treated hypertensive (HT) subjects. Twenty-one men participated in the study, 8 HT under drug treatment regimen and achieving adequate BP control before inclusion and 13 normotensive (NT). The RT protocol consisted of 12 sessions with eight exercises (leg extension, leg press, leg curl, bench press, seated row, triceps push-down, seated calf flexion, and seated arm curl) performed for two sets of 15-20 repetitions with 50% of one repetition maximum with 2-minute rest intervals in between sets, 3×/week. Heartbeat measurements were taken before and after RT, and BP was measured at the beginning and at the end of each session after 10-minute rest. The repeated measures analysis of variance (effect: group vs. training) evaluated BP and HRV responses. Effect size (ES) calculation measured the magnitude of the RT effect on these variables. There was a statistically significant reduction in postexercise systolic BP in both groups (p = 0.040), without significant change in resting BP along RT (p = 0.159). Regarding HRV, it was observed a reduced sympathetic-vagal balance (training interaction vs. group: p = 0.058, ES = -0.83) in HT subjects. Resistance training promotes a significant acute reduction of BP in the HT and NT groups and provides a slight benefit of cardiac autonomic balance in the HT.

Cardiac autonomic changes in middle-aged women: identification based on principal component analysis.

The purpose of this study was to investigate the application of the principal component analysis (PCA) technique on power spectral density function (PSD) of consecutive normal RR intervals (iRR) aiming at assessing its ability to discriminate healthy women according to age groups: young group (20-25 year-old) and middle-aged group (40-60 year-old). Thirty healthy and non-smoking female volunteers were investigated (13 young [mean ± SD (median): 22·8 ± 0·9 years (23·0)] and 17 Middle-aged [51·7 ± 5·3 years (50·0)]). The iRR sequence was collected during ten minutes, breathing spontaneously, in supine position and in the morning, using a heart rate monitor. After selecting an iRR segment (5 min) with the smallest variance, an auto regressive model was used to estimate the PSD. Five principal component coefficients, extracted from PSD signals, were retained for analysis according to the Mahalanobis distance classifier. A threshold established by logistic regression allowed the separation of the groups with 100% specificity, 83·2% sensitivity and 93·3% total accuracy. The PCA appropriately classified two groups of women in relation to age (young and Middle-aged) based on PSD analysis of consecutive normal RR intervals.

Further comments on oral transmission of Chagas' disease in Brazil: epidemiology, geographical distribution and viability of the infective parasite.

In 2006, Brazilian government received the international certificate of interruption of the vectorial transmission of Chagas' disease. However, outbreaks reported in Brazilian Amazon rainforest bear a regular occurrence and represents a relevant regional epidemiological gauge. The wild life cycle of the Chagas' disease transmission (i.e., triatomine-marsupial cycle) is present outside the previously reported endemic belt, ubiquitously, as infective triatomines can be demonstrated in Palm trees widespread all over the Amazon rainforest. As humans invade the rainforest, one is incidentally caught up and further becomes' an active part of American trypanosomiasis wild life cycle.

Comments on the letter by Ribeiro et al.: impairment of parasympathetic-mediated autonomic modulation of the heart in Chagas' cardiomyopathy: parasympathetic modulation vs. tonus.

Chagas' disease is complex immune-mediated disease originated after Trypanosome cruzi transmission, and a major cause of heart failure in Latin American continent. Auto-antibodies directed to type 2 muscarinic parasympathetic (M2) receptors seem to play key roles on the pathogenesis of heart disease, in particular in the impairment of the cardiac autonomic modulation. When talking about M2 agonistic effects, one should first argue about the differences between the terms 'modulation' and 'tonus' before describing possible autonomic influences on the heart.

Predictors of mortality in Chagas' disease: the impact of atrial fibrillation and oral transmission on infected population.

Long-term adverse outcomes in Chagas' disease are related to functional, electrical and morphological abnormalities observed in the heart of infected subjects at disease presentation. Both development of acute atrial fibrillation during the time course of the disease and orally transmitted trypanosome infection are further harbingers of poor prognosis. Chagas' disease is a challenging condition in the 21st century, and health care providers and governments are urged to implement joint actions to reduce the impact of the disease by developing preventive actions.

Ionic mechanisms and vectorial model of early repolarization pattern in the surface electrocardiogram of the athlete.

BACKGROUND: The electrocardiogram (ECG) of the athlete displays particular characteristics as a consequence of both electrophysiological and autonomic remodeling of the heart that follows continued physical training. However, doubts persist on how these changes directly interact during ventricular activation and repolarization ultimately affecting surface ECG waveforms in athletes. OBJECTIVE: This article considers an in deep rationale for the electrocardiographic pattern known as early repolarization based on both electrophysiological mechanisms at cellular level and the vectorial theory of the cardiac activation. METHODS: The mechanism by which the autonomic remodeling influences the cardiac electrical activation is reviewed and an insight model of the ventricular repolarization based on ionic models and the vectorial theory of the cardiac activation is proposed. RESULTS: Considering the underlying processes related to ventricular electrical remodeling, we propose that, in athletes' heart: 1) vagal modulation increases regional electrophysiological differences in action potential phases 1 and 2 amplitudes, thus enhancing a voltage gradient between epicardial and endocardial fibers; 2) this gradient affects depolarization and repolarization timing sequences; 3) repolarization wave front starts earlier on ventricular wall and partially overcomes the end of depolarization causing an upward displacement of the J-point, ST segment elevation, and inscription of magnified T-waves amplitudes leading to characteristic surface ECG waveform patterns. CONCLUSIONS: In athletes, the association between epicardial to endocardial electrophysiological differences and early repolarization ECG pattern can be demonstrated by the vectorial theory of the ventricular activation and repolarization.

Atrial mechanical remodeling and new onset atrial fibrillation in chronic Chagas' heart disease.

Atrial fibrillation (AF) is a common arrhythmia, mechanistically linked to underlying heart disease. AF affects about one fifth of subjects with Chagas' heart disease and is a harbinger of poor prognosis. In a retrospective longitudinal analysis, 50 subjects were investigated in long-term follow-up for the first documented atrial fibrillation (AF) episode. During a follow-up of (mean+/-SD) 84.2+/-39.0 months, nine subjects developed AF (incidence: 3.3+/-1.0%/year). Five subjects had nonfatal embolic stroke and nine died due to cardiac causes. The relative risk of AF for stroke was 3.0 (p=0.22) and for cardiac death was 3.6 (p=0.04). A faster left atrial diameter (LAD) enlargement during follow-up was tracked in subjects with more severe cardiac damage at presentation, and large LAD was detected at both presentation (p=0.02) and end of follow-up (p=0.002) in subjects who experienced AF. Atrial remodeling in chronic Chagas' disease is associated with severity of underlying heart disease at presentation and impacts AF incidence in this population.

Large pericardial effusion due to peritoneopericardial fistula.

A 50 years old male with previous history of dilated cardiomyopathy was admitted to cardio-intensive unit with dyspnea, cough, ascites and lower limb edema ascending to the inguinal region. 2D-Ecocardiogram revealed large pericardial effusion, without signs of diastolic restriction. The patient underwent pericardial drainage, which rapidly recollected in the following day. Abdominal ultrasound showed fibrotic and reduced size liver and subsequent radionuclide scan demonstrated direct communication between peritoneal and pericardial spaces. With the resolution of ascites, pericardial effusion did not recur. Embryologic explanation of this rare condition is still elusive, but incomplete closure of diaphragmatic muscle and thoracic-abdominal communication may represent the model of this anatomic functional anomaly.

Austin Flint murmur re-visited.

Austin Flint murmur is a mid-diastolic rumbling audible in subjects with severe aortic regurgitation. Several theories have been raised to explain mechanistically the nature of this particular phenomenon. We briefly review severe aortic regurgitation under the light of contemporary echocardiography in an illustrative case.

Ventricular late potential duration correlates to the time of onset of electrical transients during ventricular activation in subjects post-acute myocardial infarction.

Ventricular late potentials (VLP) are electrical signals detected at the terminal region of the ventricular activation on surface ECG and often correlated to regions of fragmented electrical conduction in subjacent damaged myocardium. Intraventricular electrical transients (IVET) arisen from myocardial infarction scars may influence VLP identification depending on transient time of onset and duration. Seventy-six subjects after first ST elevation acute myocardial infarction (STEAMI) VLP were stratified according to initial myocardial wall insulted, whether anterior or inferior wall and electrical transient tracked throughout ventricular activation using spectral turbulence analysis technique. VLP were more prevalent in inferior than anterior STEAMI. No differences regarding IVET duration was observed between anterior and inferior STEAMI. Time of onset but not duration of IVET correlated to VLP duration. Scar location after STEAMI influences detection ventricular late potentials in SAECG.