Recurrence plots: a new tool for quantification of cardiac autonomic nervous system recovery after transplant

Abstract Objective: To evaluate a possible evolutionary post-heart transplant return of autonomic function using quantitative and qualitative information from recurrence plots. Methods: Using electrocardiography, 102 RR tachograms of 45 patients (64.4% male) who underwent heart transplantation and that were available in the database were analyzed at different follow-up periods. The RR tachograms were collected from patients in the supine position for about 20 minutes. A time series with 1000 RR intervals was analyzed, a recurrence plot was created, and the following quantitative variables were evaluated: percentage of determinism, percentage of recurrence, average diagonal length, Shannon entropy, and sample entropy, as well as the visual qualitative aspect. Results: Quantitative and qualitative signs of heart rate variability recovery were observed after transplantation. Conclusion: There is evidence that autonomic innervation of the heart begins to happen gradually after transplantation. Quantitative and qualitative analyses of recurrence can be useful tools for monitoring cardiac transplant patients and detecting the gradual return of heart rate variability.

Elevated Heart Rate is Associated with Cardiac Denervation in Patients with Heart Failure: A 123-Iodine-MIBG Myocardial Scintigraphy Study / Frequência Cardíaca Elevada está Associada com Desnervação Cardíaca em Pacientes com Insuficiência Cardíaca: Um Estudo com Cintilografia Miocárdica com 123-Iodo-MIBG

Abstract Background: In the Systolic Heart Failure Treatment With the If Inhibitor Ivabradine Trial (SHIFT), heart rate (HR) reduction with ivabradine was associated with improved survival and reduced hospitalizations in patients with heart failure (HF). The mechanisms by which elevated HR increases mortality are not fully understood. Objective: To assess the relationship of baseline HR with clinical, neurohormonal and cardiac sympathetic activity in patients with chronic HF and elevated HR. Method: Patients with chronic HF who were in sinus rhythm and had resting HR>70 bpm despite optimal medical treatment were included in a randomized, double-blind study comparing ivabradine versus pyridostigmine. This report refers to the baseline data of 16 initial patients. Baseline HR (before randomization to one of the drugs) was assessed, and patients were classified into two groups, with HR below or above mean values. Cardiac sympathetic activity was assessed by 123-iodine-metaiodobenzylguanidine myocardial scintigraphy. Results: Mean HR was 83.5±11.5 bpm (range 72 to 104), and seven (43.7%) patients had HR above the mean. These patients had lower 6-min walk distance (292.3±93 vs 465.2±97.1 m, p=0.0029), higher values of N-Terminal-proBNP (median 708.4 vs 76.1, p=0.035) and lower late heart/mediastinum rate, indicating cardiac denervation (1.48±0.12 vs 1.74±0.09, p<0.001). Conclusion: Elevated resting HR in patients with HF under optimal medical treatment was associated with cardiac denervation, worse functional capacity, and neurohormonal activation.

Resumo Fundamento: No SHIFT (Systolic Heart Failure Treatment With the If Inhibitor Ivabradine Trial, ou Estudo do Tratamento da Insuficiência Cardíaca Sistólica com o Inibidor de If Ivabradina), a redução da frequência cardíaca (FC) com ivabradina associou-se com melhor sobrevida e redução das hospitalizações em pacientes com insuficiência cardíaca (IC). Os mecanismos pelos quais a FC elevada aumenta a mortalidade não são totalmente compreendidos. Objetivo: Avaliar a relação da FC basal com atividade clínica, neuro-hormonal e simpática cardíaca em pacientes com IC crônica e FC elevada. Método: Pacientes com IC crônica em ritmo sinusal e FC≥70 apesar de tratamento adequado foram incluídos em um estudo duplo-cego, randomizado, que comparou ivabradina com piridostigmina. Este artigo refere-se a dados basais dos primeiros 16 pacientes. A FC basal (antes da randomização para um dos medicamentos) foi avaliada, e os pacientes classificados em dois grupos, com FC abaixo ou acima dos valores médios. A atividade simpática cardíaca foi avaliada por cintilografia com metaiodobenzilguanidina marcada com iodo 123. Resultados: A FC média foi 83,5±11,5 bpm (intervalo 72 a 104), e sete pacientes (43.7%) tinham FC acima da média. Esses pacientes apresentaram menor distância percorrida no teste de caminhada de 6 minutos (292,3±93 vs 465,2±97,1 m, p=0,0029), valores mais altos de N-terminal do pró-BNP (mediana 708,4 vs 76,1, p=0,035) e menor relação coração/mediastino tardia, indicando desnervação cardíaca (1,48±0,12 vs 1,74±0,09, p<0,001). Conclusão: A FC de repouso elevada em pacientes com IC em tratamento médico adequado associou-se com desnervação cardíaca, pior capacidade funcional e ativação neuro-hormonal.

Depressed cardiac autonomic modulation in patients with chronic kidney disease / Depressão da modulação autonômica cardíaca em pacientes com doença renal crônica diagnosticada pela análise espectral da variabilidade da frequência

Introduction: A dysfunctional autonomic nervous system (ANS) has also been recognized as an important mechanism contributing to the poor outcome in CKD patients, with several studies reporting a reduction in heart rate variability (HRV). Objective: Evaluate the sympathovagal balance in patients with chronic kidney disease on conservative treatment. Methods: In a cross-sectional study, patients with CKD stages 3, 4 and 5 not yet on dialysis (CKD group) and age-matched healthy subjects (CON group) underwent continuous heart rate recording during two twenty-minute periods in the supine position (pre-inclined), followed by passive postural inclination at 70° (inclined period). Power spectral analysis of the heart rate variability was used to assess the normalized low frequency (LFnu), indicative of sympathetic activity, and the normalized high frequency (HFnu), indicative of parasympathetic activity. The LFnu/HFnu ratio represented sympathovagal balance. Results: After tilting, CKD patients had lower sympathetic activity, higher parasympathetic activity, and lower sympathovagal balance than patients in the CON group. Compared to patients in stage 3, patients in stage 5 had a lower LFnu/HFnu ratio, suggesting a more pronounced impairment of sympathovagal balance as the disease progresses. Conclusion: CKD patients not yet on dialysis have reduced HRV, indicating cardiac autonomic dysfunction early in the course of CKD. .

Introdução: Um sistema nervoso autônomo disfuncionante tem sido relacionado a eventos cardiovasculares em pacientes com doença renal crônica (DRC), com vários estudos demonstrando redução da variabilidade da frequência cardíaca e o desenvolvimento de arritmias complexas nestes pacientes. Objetivo: Avaliar o balanço simpático-vagal em pacientes com DRC em tratamento conservador. Métodos: Em estudo transversal, foram avaliados pacientes com DRC estágios 3, 4 e 5 não dialítico pareados para indivíduos saudáveis. Todos os voluntários foram submetidos à monitorização contínua da frequência cardíaca durante, por 20 minutos na posição supina (período pré-inclinado), seguido de inclinação passiva a 70 graus por mais 20 minutos (período inclinado). A análise espectral da variabilidade da frequência cardíaca foi usada para se obter a baixa frequência normalizada (LF nu), indicativa da atividade simpática, e a alta frequência normalizada (HF nu), indicativa da atividade parassimpática. A razão entre essas duas variáveis (LF nu/HF nu) é representativa do balanço simpático-vagal. Resultados: Durante o período pré-inclinado, não houve diferença significativa da variabilidade da frequência cardíaca entre os pacientes com DRC e o grupo controle. No entanto, após a inclinação, os pacientes com DRC apresentaram menor atividade simpática, maior atividade parassimpática e menor balanço simpático-vagal quando comparados com o grupo controle. Comparados com pacientes em estágio 3, pacientes em estágio 5 apresentaram menor razão LFnu/HFnu, sugerindo piora do balanço simpático-vagal nos estágios mais avançados da DRC. Conclusão: Pacientes ...

Ativação adrenérgica intramiocárdica na cardiomiopatia chagásica e doença arterial coronariana / Intramyocardial adrenergic activation in chagasic cardiomyopathy and coronary artery disease / Activación adrenérgica intramiocárdica en la cardiomiopatía chagásica y enfermedad arterial coronaria

FUNDAMENTO: A norepinefrina miocárdica está alterada na disfunção ventricular esquerda. Em pacientes com cardiomiopatia chagásica (CC), essa questão ainda não foi discutida. OBJETIVO: Determinar o nível de norepinefrina (NE) miocárdica em pacientes com CC e compará-la em pacientes com doença arterial coronariana (DAC) e relacionar NE miocárdica com a fração de ejeção do ventrículo esquerdo (FEVE). MÉTODOS: Estudamos 39 pacientes com CC, divididos em grupo 1: 21 indivíduos com FEVE normal e grupo 2: 18 com FEVE diminuída. Dezessete pacientes com DAC foram divididos em grupo 3: 12 indivíduos com FEVE normal e grupo 4: 5 indivíduos com FEVE diminuída. Ecocardiografia bidimensional foi usada para medir a FEVE. A NE miocárdica foi determinada através de Cromatografia Líquida de Alta Eficiência (HPLC). RESULTADOS: A NE miocárdica na CC com e sem disfunção ventricular foi 1,3±1,3 e 6,1±4,2 pg/μg de proteína não-colagenosa, respectivamente (p<0,0001); na DAC com e sem disfunção ventricular, foi 3,3±3,0 e 9,8±4,2 pg/μg de proteína não-colagenosa, respectivamente (p<0,0001). Uma correlação positive foi observada entre a FEVE e a concentração de NE miocárdica em pacientes com CC (p<0,01; r = 0,57) e também naqueles com DAC (p<0,01; r=0,69). Uma diferença significante foi demonstrada entre as concentrações de NE em pacientes com FEVE normal (grupos 1 e 3; p = 0,0182), mas nenhuma diferença foi observada em pacientes com FEVE diminuída (grupos 2 e 4; p = 0,1467). CONCLUSÃO: Pacientes com CC e fração de ejeção global normal apresentam uma denervação cardíaca precoce, quando comparados à pacientes com doença arterial coronariana.

BACKGROUND: Myocardial norepinephrine is altered in left ventricular impairment. In patients with Chagas' cardiomyopathy (CC), this issue has not been addressed. OBJECTIVE: To determine the level of myocardial norepinephrine in patients with CC and compare it in patients with coronary artery disease, and to relate myocardial norepinephrine to left ventricular ejection fraction (LVEF). METHODS: We studied 39 patients with CC, divided into group 1: 21 individuals with normal LVEF and group 2: 18 individuals with decreased LVEF. Seventeen patients with coronary artery disease were divided into group 3: 12 individuals with normal LVEF and group 4: 5 individuals with decreased LVEF. Two-dimensional echocardiography was used to measure LVEF. Myocardial norepinephrine was determined by high-performance liquid chromatography. RESULTS: Myocardial norepinephrine in CC with and without ventricular dysfunction was 1.3±1.3 and 6.1±4.2 pg/μg noncollagen protein, respectively (p<0.0001); in coronary artery disease with and without ventricular dysfunction, it was 3.3±3.0 and 9.8±4.2 pgμg noncollagen protein, respectively (p<0.0001). A positive correlation was found between LVEF and myocardial norepinephrine concentration in the patients with Chagas' cardiomyopathy (p<0.01, r = 0.57) and also in those with coronary artery disease (p<0.01, r=0.69). A significant difference was demonstrated between norepinephrine concentrations in patients with normal LVEF (groups 1 and 3; p = 0.0182), but no difference was found in patients with decreased LVEF (groups 2 and 4; p = 0.1467). CONCLUSION: In patients with Chagas' cardiomyopathy and normal global ejection fraction there is an early cardiac denervation, when compared to coronary artery disease patients.

FUNDAMENTO: La norepinefrina miocárdica está alterada en la disfunción ventricular izquierda. En pacientes con cardiomiopatía chagásica (CC), esa cuestión aun no fue discutida. OBJETIVO: Determinar el nivel de norepinefrina (NE) miocárdica en pacientes con CC y compararla en pacientes con enfermedad arterial coronaria (EAC) y relacionar NE miocárdica con la fracción de eyección del ventrículo izquierdo (FEVI). MÉTODOS: 39 pacientes con CC, divididos en grupo 1: 21 individuos con FEVI normal y grupo 2: 18 con FEVI disminuida. Diecisiete pacientes con EAC fueron divididos en grupo 3: 12 individuos con FEVI normal y grupo 4: 5 individuos con FEVI disminuida. Ecocardiografía bidimensional fue usada para medir la FEVI. La NE miocárdica fue determinada a través de Cromatografía Líquida de Alta Eficiencia (HPLC). RESULTADOS: La NE miocárdica en la CC con y sin disfunción ventricular fue 1,3±1,3 y 6,1±4,2 pg/µg de proteína no colagenosa, respectivamente (p<0,0001); en la EAC con y sin disfunción ventricular, fue 3,3±3,0 y 9,8±4,2 pg/µg de proteína no colagenosa, respectivamente (p<0,0001). Una correlación positiva fue observada entre la FEVI y la concentración de NE miocárdica en pacientes con CC (p<0,01; r=0,57) y también en aquellos con EAC (p<0,01; r=0,69). Una diferencia significativa fue demostrada entre las concentraciones de NE en pacientes con FEVI normal (grupos 1 y 3; p = 0,0182), pero ninguna diferencia fue observada en pacientes con FEVI disminuida (grupos 2 y 4; p = 0,1467). CONCLUSIONES: Pacientes con CC y fracción de eyección global normal presentan una denervación cardíaca precoz, cuando son comparados a pacientes con enfermedad arterial coronaria.

Efeito do carvedilol a curto prazo na atividade simpática cardíaca pela cintilografia com 123I-MIBG / Effects of short-term carvedilol on the cardiac sympathetic activity assessed by 123I-MIBG scintigraphy

FUNDAMENTO: Alterações autonômicas na insuficiência cardíaca estão associadas a um aumento da morbimortalidade. Vários métodos não invasivos têm sido empregados para avaliar a função simpática, incluindo a imagem cardíaca com 123I-MIBG. OBJETIVO: Avaliar a atividade simpática cardíaca, por meio da cintilografia com 123I-MIBG, antes e após três meses de terapia com carvedilol em pacientes com insuficiência cardíaca com fração de ejeção do VE <45 por cento (FEVE). MÉTODOS: Foram recrutados para o estudo 16 pacientes, com idade média de 56,3 ± 12,6 anos (11 do sexo masculino), fração de ejeção média de 28 por cento ± 8 por cento e sem uso prévio de betabloqueadores. Realizaram-se imagens da inervação cardíaca com 123I-MIBG, determinando os níveis séricos de catecolaminas (epinefrina, dopamina e norepinefrina), e empreendeu-se a ventriculografia radionuclídica antes e após o uso de carvedilol por três meses. RESULTADOS: Houve melhora da classe funcional dos pacientes: antes do tratamento, metade se encontrava em CF II (50 por cento) e metade em CF III. Após 3 meses, 7 pacientes encontravam-se em CF I (43,8 por cento) e 9 em CF II (56,2 por cento), (p = 0,0001). A FEVE média avaliada pela ventriculografia radionuclídica aumentou de 29 por cento para 33 por cento (p = 0,017). Não houve variação significativa da atividade adrenérgica cardíaca avaliada pelo 123I-MIBG (imagem precoce, tardia e taxa de washout). Não foi observada variação significativa nas dosagens das catecolaminas. CONCLUSÃO: O tratamento em curto prazo com carvedilol promoveu a melhora clínica e da FEVE. Entretanto, não foi associado à melhora da atividade adrenérgica cardíaca pela cintilografia com 123I-MIBG, bem como da dosagem das catecolaminas circulantes.

BACKGROUND: Autonomic alterations in heart failure are associated with an increase in morbimortality. Several noninvasive methods have been employed to evaluate the sympathetic function, including the Meta-Iodobenzylguanidine (123I-MIBG) scintigraphy imaging of the heart. OBJECTIVE: to evaluate the cardiac sympathetic activity through 123I-MIBG scintigraphy, before and after three months of carvedilol therapy in patients with heart failure and left ventricular ejection fraction (LVEF) < 45 percent. PATIENTS AND METHODS: Sixteen patients, aged 56.3 ± 12.6 years (11 males), with a mean LVEF of 28 percent ± 8 percent and no previous use of beta-blockers were recruited for the study. Images of the heart innervation were acquired with 123I-MIBG, and the serum levels of catecholamines (epinephrine, dopamine and norepinephrine) were measured; the radioisotope ventriculography (RIV) was performed before and after a three-month therapy with carvedilol. RESULTS: Patients' functional class showed improvement: before the treatment, 50 percent of the patients were FC II and 50 percent were FC III. After 3 months, 7 patients were FC I (43.8 percent) and 9 were FC II (56.2 percent), (p = 0.0001). The mean LVEF assessed by RIV increased from 29 percent to 33 percent (p = 0.017). There was no significant variation in cardiac adrenergic activity assessed by 123I-MIBG (early and late resting images and washout rate). No significant variation was observed regarding the measurement of catecholamines. CONCLUSION: The short-term treatment with carvedilol promoted the clinical and LVEF improvement. However, this was not associated to an improvement in the cardiac adrenergic activity, assessed by 123I-MIBG scintigraphy, as well as the measurement of circulating catecholamines.

Lower cardiac vagal tone in non-obese healthy men with unfavorable anthropometric characteristics

Objectives: to determine if there are differences in cardiac vagal tone values in non-obese healthy, adult men with and without unfavorable anthropometric characteristics. Introduction: It is well established that obesity reduces cardiac vagal tone. However, it remains unknown if decreases in cardiac vagal tone can be observed early in non-obese healthy, adult men presenting unfavorable anthropometric characteristics. Methods: Among 1688 individuals assessed between 2004 and 2008, we selected 118 non-obese (BMI <30 kg/m²), healthy men (no known disease conditions or regular use of relevant medications), aged between 20 and 77 years old (42 ± 12-years-old). Their evaluation included clinical examination, anthropometric assessment (body height and weight, sum of six skinfolds, waist circumference and somatotype), a 4-second exercise test to estimate cardiac vagal tone and a maximal cardiopulmonary exercise test to exclude individuals with myocardial ischemia. The same physician performed all procedures. Results: A lower cardiac vagal tone was found for the individuals in the higher quintiles - unfavorable anthropometric characteristics - of BMI (p=0.005), sum of six skinfolds (p=0.037) and waist circumference (p<0.001). In addition, the more endomorphic individuals also presented a lower cardiac vagal tone (p=0.023), while an ectomorphic build was related to higher cardiac vagal tone values as estimated by the 4-second exercise test (r=0.23; p=0.017). Conclusions: Non-obese and healthy adult men with unfavorable anthropometric characteristics tend to present lower cardiac vagal tone levels. Early identification of this trend by simple protocols that are non-invasive and risk-free, using select anthropometric characteristics, may be clinically useful in a global strategy to prevent cardiovascular disease.

Training-related changes in the R-R interval at the onset of passive movements in humans

The aim of the present study was to determine whether training-related alterations in muscle mechanoreflex activation affect cardiac vagal withdrawal at the onset of exercise. Eighteen male volunteers divided into 9 controls (26 ± 1.9 years) and 9 racket players (25 ± 1.9 years) performed 10 s of voluntary and passive movement characterized by the wrist flexion of their dominant and non-dominant limbs. The respiratory cycle was divided into four phases and the phase 4 R-R interval was measured before and immediately following the initiation of either voluntary or passive movement. At the onset of voluntary exercise, the decrease in R-R interval was similar between dominant and non-dominant forearms in both controls (166 ± 20 vs 180 ± 34 ms, respectively; P > 0.05) and racket players (202 ± 29 vs 201 ± 31 ms, respectively; P > 0.05). Following passive movement, the non-dominant forearm of racket players elicited greater changes than the dominant forearm (129 ± 30 vs 77 ± 17 ms; P < 0.05), as well as both the dominant (54 ± 20 ms; P < 0.05) and non-dominant (59 ± 14 ms; P < 0.05) forearms of control subjects. In contrast, changes in R-R interval elicited by the racket players' dominant forearm were similar to that observed in the control group, indicating that changes in R-R interval at the onset of passive exercise were not attenuated in the dominant forearm of racket players. In summary, cardiac vagal withdrawal induced by muscle mechanoreflex stimulation is well-maintained, despite long-term exposure to training.

Efeito da denervação cardíaca ventral na incidência de fibrilação atrial após revascularização cirúrgica do miocárdio / Effect of ventral cardiac denervation in the incidence of atrial fibrilation after coronary artery bypass graft surgery

OBJETIVO: Verificar o efeito da denervação cardíaca ventral na incidência de fibrilação atrial no pós-operatório de revascularização cirúrgica do miocárdio. MÉTODOS: Entre setembro e novembro de 2005, 50 pacientes consecutivos da mesma instituição foram alocados neste estudo prospectivo e randomizado. Foram selecionados pacientes portadores de insuficiência coronariana com indicação de revascularização cirúrgica do miocárdio, sem história ou diagnóstico prévio de arritmia atrial. Os critérios de exclusão foram: idade acima de 75 anos, história prévia de arritmia atrial e operações cardíacas associadas. A denervação era realizada antes do início da circulação extracorpórea pela remoção do tecido gorduroso ao redor da veia cava superior, aorta e artéria pulmonar. Os grupos foram comparados de acordo com as características clínicas, demográficas e variáveis operatórias. RESULTADOS: Não houve mortalidade hospitalar em ambos os grupos. O tempo médio adicional para realização da denervação foi de 7,64 + 2,33 minutos e não houve complicações associadas ao procedimento. Cinco pacientes apresentaram fibrilação atrial no pós-operatório, sendo dois (8 por cento) no grupo controle e três (12 por cento) no grupo denervação. O risco dos pacientes do grupo denervação apresentarem fibrilação atrial foi 22 por cento maior do que no grupo controle (intervalo de confiança, 0,56-2,66), porém, este resultado não foi estatisticamente significativo (p=0,64). CONCLUSÕES: A denervação cardíaca ventral, apesar de rápida execução e de baixo risco, não apresentou efeito na redução da incidência de fibrilação atrial no pós-operatório de revascularização cirúrgica do miocárdio.

OBJECTIVE: To evaluate the effect of ventral cardiac denervation in the incidence of atrial fibrillation after coronary artery bypass surgery. METHODS: Between September and November, 50 patients without history or previous diagnosis of atrial arrhythmia from the same institution presenting coronary heart disease with indication for coronary artery graft bypass surgery were enrolled in a prospective and randomized study. The exclusion criteria were: patients older than 75 years of age, previous history of atrial arrhythmia and associated heart surgeries. Denervation was performed before cardiopulmonary bypass and it was achieved by removing the adipose tissues around the superior vena cava, aorta and pulmonary artery. The groups were compared regarding demographic, clinical and operative variables. RESULTS: There were no hospital mortalities. The additional time for the denervation was 7.64±2.33 minutes, and there were no associated complications. Postoperative atrial fibrillation was present in two (8 percent) patients of the Control Group and in three (12 percent) patients who underwent ventral cardiac denervation. The risk of postoperative atrial fibrillation in patients undergoing ventral cardiac denervation was 22 percent higher than in the Control Group (0.56-2.66,confidence interval); however, this outcome was not statistically significant (p=0.64). CONCLUSION: Ventral cardiac denervation, despite being a fast and low-risk procedure, does not significantly reduce the incidence of atrial fibrillation after coronary artery bypass graft surgery.

Role of the cardiac nerve in the adaptive changes of heart rate in response to an aversive stimulus in Megalobulimus mogianensis

The effect of an aversive stimulus represented by contact with a hot plate on the heart rate of Megalobulimus mogianensis was evaluated with electrocardiogram recording in intact snails (N = 8). All stimulated animals showed an increase in heart rate, with mean values ranging from 35.6 ± 1.2 (basal heart rate) to 43.8 ± 0.9 bpm (post-stimulation heart rate). The cardioacceleration was followed by gradual recovery of the basal heart rate, with mean recovery times varying from 4.3 ± 0.3 to 5.8 ± 0.6 min. Repetition of the stimulus did not affect the magnitude of variation nor did it influence the basal heart rate recovery time. To investigate the role of the cardiac nerve in mediating the heart rate alterations induced by the aversive stimulus, denervated (N = 8) and sham-operated (N = 8) animals were also tested. Although the aversive stimulus caused the heart rate to increase significantly in both experimental groups, the mean increase in heart rate in denervated animals (4.4 ± 0.4 bpm) was 57 percent of the value obtained in sham-operated animals (7.7 ± 1.3 bpm), indicating that the cardiac nerve is responsible for 43 percent of the cardioacceleration induced by the aversive stimulus. The cardioacceleration observed in denervated snails may be due to an increase in venous return promoted by the intense muscular activity associated with the withdrawal response. Humoral factors may also be involved. A probable delaying inhibitory effect of the cardiac nerve on the recuperation of the basal heart rate is suggested.

Angina secundaria a lesión de tronco coronario izquierdo post trasplante cardiaco: Evidencias de reinervación simpática tardía / Angina after a heart transplant with evidence of late sympathetic reinnervation: Report of one case

We report a 56 years-old man presenting with chest pain with exercise, seven years after an orthotopic heart transplant. A coronary angiography showed an atherosclerotic lesion in the common left main coronary artery with more than 90 percent obstruction. The lesion was successfully treated with a transluminal angioplasty with stenting. A 131-1 metaiodobenylguanidine (MIBG) scan demonstrated sympathetic reinnervation. Sixteen months later, due to progression of allograft vasculopathy, coronary artery bypass was required.

Autonomic modulation of heart rate of young and postmenopausal women undergoing estrogen therapy

The aim of the present study was to determine whether estrogen therapy (ET) reduces alterations of the autonomic control of heart rate (HR) due to hypoestrogenism and aging. Thirteen young (24 ± 2.6 years), 10 postmenopausal (53 ± 4.6 years) undergoing ET (PM-ET), and 14 postmenopausal (56 ± 2.6 years) women not undergoing ET (PM) were studied. ET consisted of 0.625 mg/day conjugated equine estrogen. HR was recorded continuously for 8 min at rest in the supine and sitting positions. HR variability (HRV) was analyzed by time (SDNN and rMSSD indices) and frequency domain methods. Power spectral components are reported as normalized units (nu) at low (LF) and high (HF) frequencies, and as LF/HF ratio. Intergroup comparisons: SDNN index was higher in young (median: supine, 47 ms; sitting, 42 ms) than in PM-ET (33; 29 ms) and PM (31; 29 ms) women (P < 0.05). PM showed lower HFnu, higher LFnu and higher LF/HF ratio (supine: 44, 56, 1.29; sitting: 38, 62, 1.60) than the young group in the supine position (61, 39, 0.63) and the PM-ET group in the sitting position (57, 43, 0.75; P < 0.05). Intragroup comparisons: HR was lower in the supine than in the sitting position for all groups (P < 0.05). The HRV decrease from the supine to the sitting position was significant only in the young group. These results suggest that HRV decreases during aging. ET seems to attenuate this process, promoting a reduction in sympathetic activity on the heart and contributing to the cardioprotective effect of estrogen hormones.

Cardiac Autonomic Function Evaluated by the Heart Rate Turbulence Method was not Changed in Obese Patients without Co-morbidities

Obese subjects are more prone to sudden deaths and arrhythmias than non-obese subjects. Heart rate turbulence (HRT) impairment reflects cardiac autonomic dysfunction, in particular impaired baroreflex sensitivity and reduced parasympathetic activity. Our aim was to evaluate the cardiac autonomic function in obesity by the HRT method. Ninety obese subjects and 112 healthy subjects were included in the study. Twenty-four hours ambulatory electrocardiograms were recorded and Holter recordings were analyzed. HRT parameters, turbulence onset (TO) and turbulence slope (TS), were calculated with HRT View Version 0.60-0.1 software program. HRT were calculated in 43 obese and 43 control subjects who had at least one ventricular premature beat in their Holter recordings. We excluded 47 obese patients and 69 control subjects who showed no ventricular premature beats in their Holter recordings from the statistical analysis. There were no significant differences in TO and TS between obese and control subjects (TO obese: -1.6+/-2.2%, TO control: -2.1+/-2.6%, p>0.05; TS obese: 8.2+/-5.2, TS control: 10.1+/-6.7, p>0.05, respectively). HRT parameters seem to be normal in obese patients without comorbidities.

Jervell-Lange Nielsen syndrome in a family with the long QT Syndrome (LQTS).

A child with Jervell-Lange Nielsen syndrome is presented from Kolkata. Family study showed that the other family members are suffering from long QT syndrome. The child had frequent syncopal attack and very prolonged QT interval requiring left cardiac sympathetic denervation and beta-blocker therapy as patient could not afford implantable defibrillator and cardiac pacing.

Role of the cardiac nerve in the effect of a novel innocuous stimulus on the heart rate of Megalobulimus mogianensis

The effects of a brief jet of water delivered to the anterior portion of body-head on the heart rate of Megalobulimus mogianensis were determined in a group of intact snails (N = 8), previously prepared for electrocardiogram recording. The heart rate was significantly increased following stimulation. Nevertheless, with repetition of the stimulus there was a significant decrease in the magnitude of the heart rate variation and in the time for the basal heart rate to recover (first stimulus, 7.4 ± 1.2 bpm and 15.5 ± 1.8 min; second stimulus, 4.8 ± 1.0 bpm and 10.6 ± 1.5 min; third stimulus, 5.0 ± 0.3 bpm and 11.1 ± 1.8 min), indicating that this behavioral response undergoes early habituation. To determine the role of the cardiac nerve in mediating the heart rate alterations induced by the jet of water two other groups were tested: denervated animals (N = 8) and sham-operated control animals (N = 8). Although the innocuous stimulus caused the heart rate to increase significantly in both experimental groups, the mean increase in heart rate in denervated animals (3.2 ± 0.4 bpm) was 41 percent of the value obtained in sham-operated animals (7.8 ± 1.5 bpm), indicating that the cardiac nerve is responsible for 59 percent of the cardioacceleration induced by the innocuous stimulus. The increase in heart rate observed in denervated animals may be due to an increase in venous return promoted by the intense muscular activity associated with the retraction-protraction of the anterior part of the body induced by the jet of water.

Respostas autonômicas cardíacas à manobra de tilt em adolescentes obesos / Cardiac autonomic responses to head-up tilt in obese adolescents

INTRODUÇÃO: A obesidade está associada às alterações do sistema nervoso autônomo. Estudos prévios em adultos têm mostrado que obesos apresentam resposta autonômica cardíaca diminuída frente a mudanças posturais. Contudo, pouco se sabe sobre o impacto do sobrepeso na adolescência quanto às respostas autonômicas ao estresse postural passivo. OBJETIVO: Comparar as respostas autonômicas cardíacas à manobra de tilt entre adolescentes obesos e não-obesos mediante análise da variabilidade da freqüência cardíaca (VFC). MÉTODOS: Quatorze adolescentes obesos (15,5±1,6 anos) foram comparados com 20 adolescentes não-obesos (15,4±0,8 anos). A modulação autonômica cardíaca foi estudada mediante análise da variabilidade da freqüência cardíaca de trechos de cinco minutos de registro de intervalos RR antes e depois da inclinação da mesa de tilt a 70°. A VFC foi estudada no domínio do tempo (DT) e no domínio da freqüência (DF). Os componentes espectrais foram estudados na baixa (LF) e na alta freqüência (HF) e pela razão LF/HF. RESULTADOS: Adolescentes obesos demonstraram menor HF em unidades normalizadas (38,2±11.1 vs 53,9±15,5, p<0,05) e maior LF em unidades normalizadas (60,7±11,3 vs 44,6±15,7, p<0,05) na posição supina. Nenhuma diferença foi encontrada nos parâmetros da VFC após a manobra de tilt. Ao comparar a diferença entre as posições ortostática e supino, os adolescentes obesos apresentaram menores mudanças de LF unidades normalizadas (22,4±12,6 vs 38±16,4, p<0,05) e HF unidades normalizadas (-21,9±12,4 vs _37,3±16,3, p<0,05). CONCLUSÃO: Adolescentes obesos apresentaram uma resposta autonômica cardíaca alterada frente ao estresse postural, caracterizada principalmente por uma hiporesponsividade vagal.

Effects of age and physical activity on the autonomic control of heart rate in healthy men

The effects of the aging process and an active life-style on the autonomic control of heart rate (HR) were investigated in nine young sedentary (YS, 23 ± 2.4 years), 16 young active (YA, 22 ± 2.1 years), 8 older sedentary (OS, 63 ± 2.4 years) and 8 older active (OA, 61 ± 1.1 years) healthy men. Electrocardiogram was continuously recorded for 15 min at rest and for 4 min in the deep breathing test, with a breath rate of 5 to 6 cycles/min in the supine position. Resting HR and RR intervals were analyzed by time (RMSSD index) and frequency domain methods. The power spectral components are reported in normalized units (nu) at low (LF) and high (HF) frequency, and as the LF/HF ratio. The deep breathing test was analyzed by the respiratory sinus arrhythmia indices: expiration/inspiration ratio (E/I) and inspiration-expiration difference (deltaIE). The active groups had lower HR and higher RMSSD index than the sedentary groups (life-style condition: sedentary vs active, P < 0.05). The older groups showed lower HFnu, higher LFnu and higher LF/HF ratio than the young groups (aging effect: young vs older, P < 0.05). The OS group had a lower E/I ratio (1.16) and deltaIE (9.7 bpm) than the other groups studied (YS: 1.38, 22.4 bpm; YA: 1.40, 21.3 bpm; OA: 1.38, 18.5 bpm). The interaction between aging and life-style effects had a P < 0.05. These results suggest that aging reduces HR variability. However, regular physical activity positively affects vagal activity on the heart and consequently attenuates the effects of aging in the autonomic control of HR.

Conceitos básicos na estimulação cardíaca / Cardiac estimulation basic concepts

A estimulação cardíaca é possível com relativa facilidade graças à natureza sincicial do miocárdio, que funcona como uma célula. Um estímulo aplicado em qualquer parte do miocárdio propaga-se imediatamente, por condução muscular, para todas as células, sem a necessidade de inervação ou de mediadores químicos, devido à existência, entre as células miocárdicas, dos discos intercalares, que são verdadeiras sinapses elétricas altamente eficazes.