Aumento do trabalho miocárdico desperdiçado como indicador de lesão coronariana significativa / Increased wasted myocardial work as an indicator of significant coronary lesion

Introdução: A avaliação dos índices de trabalho miocárdico global em condições basais pode ser útil para a estratificação clínica de pacientes com suspeita de obstrução coronariana. Objetivo: Correlacionar o valor do índice de trabalho miocárdico global e a presença de lesões obstrutivas coronarianas significativas. Método: Estudo transversal, com pacientes encaminhados para cinecoronarioangiografia eletiva. Foi realizado ecocardiograma com obtenção das medidas para cálculo do valor do trabalho miocárdico, sendo avaliada a presença de lesões obstrutivas coronarianas significativas à cinecoronarioangiografia. Resultados: A amostra foi composta de 30 pacientes, com a idade média de 64,2±12,8 anos, sendo a maioria do sexo masculino (63,3%), dos quais 68,4% apresentaram lesões obstrutivas coronarianas significativas. O índice de trabalho miocárdico global foi de 1.876mmHg%±253,8 no grupo com lesões obstrutivas coronarianas significativas e de 2.054,2mmHg%±417,3 naqueles sem lesões significativas (p=0,089). O trabalho miocárdio construtivo global nos pacientes sem lesões obstrutivas coronarianas significativas foi maior (2.329,3mmHg%±462,9) do que naqueles com lesões obstrutivas coronarianas significativas (2.109,5mmHg%±332,3; p=0,064). O trabalho miocárdio desperdiçado global foi maior nos pacientes com lesões obstrutivas coronarianas significativas (103,7mmHg%±47,1 versus 68,3mmHg%±33,8; p=0,038). O ponto de corte de 115mmHg% foi aquele com a melhor área sob a curva (0,625), com sensibilidade de 83,3%. Conclusão: O aumento do trabalho miocárdio desperdiçado global se correlacionou com a presença de lesões obstrutivas coronarianas significativas em nossa amostra.(AU)

Introduction: The assessment of global myocardial work indices under baseline conditions may be useful for the clinical stratification of patients with suspected coronary obstruction. Objective: To correlate the value of global myocardial work indices and the presence of significant obstructive coronary lesions. Method: Cross-sectional study, with patients referred for elective coronary angiography. An echocardiogram was performed to obtain measurements to calculate the value of myocardial work and evaluated the presence or presence of significant obstructive coronary lesions at coronary angiography. Results: The sample consisted of 30 patients, with a mean age of 64.2±12.8 years, the majority being male (63.3%), of which 68.4% had significant obstructive coronary lesions. The global myocardial work indices was 1,876mmHg%±253.8 in the group with significant obstructive coronary lesions and 2,054.2mmHg%±417.3 in those without significant lesions (p=0.089). Global constructive myocardial work in patients without significant obstructive coronary lesions was higher (2,329.3mmHg%±462.9) than in those with significant obstructive coronary lesions (2,109.5mmHg%±332.3; p=0.064). Global wasted myocardial work was higher in patients with significant obstructive coronary lesions (103.7mmHg%±47.1 versus 68.3mmHg%±33.8; p=0.038). The cutoff point of 115 mmHg% was the one with the best area under the curve (0.625), with a sensitivity of 83.3%. Conclusion: The increase in global wasted myocardial work correlated with the presence of significant obstructive coronary lesions in our sample. (AU)

Cardiac protein expression patterns are associated with distinct inborn exercise capacity in non-selectively bred rats

In the present study, we successfully demonstrated for the first time the existence of cardiac proteomic differences between non-selectively bred rats with distinct intrinsic exercise capacities. A proteomic approach based on two-dimensional gel electrophoresis coupled to mass spectrometry was used to study the left ventricle (LV) tissue proteome of rats with distinct intrinsic exercise capacity. Low running performance (LRP) and high running performance (HRP) rats were categorized by a treadmill exercise test, according to distance run to exhaustion. The running capacity of HRPs was 3.5-fold greater than LRPs. Protein profiling revealed 29 differences between HRP and LRP rats (15 proteins were identified). We detected alterations in components involved in metabolism, antioxidant and stress response, microfibrillar and cytoskeletal proteins. Contractile proteins were upregulated in the LVs of HRP rats (α-myosin heavy chain-6, myosin light chain-1 and creatine kinase), whereas the LVs of LRP rats exhibited upregulation in proteins associated with stress response (aldehyde dehydrogenase 2, α-crystallin B chain and HSPβ-2). In addition, the cytoskeletal proteins desmin and α-actin were upregulated in LRPs. Taken together, our results suggest that the increased contractile protein levels in HRP rats partly accounted for their improved exercise capacity, and that proteins considered risk factors to the development of cardiovascular disease were expressed in higher amounts in LRP animals.

Efficacy of cardiac resynchronization with defibrillator insertion in patients undergone coronary artery bypass graft: A cohort study of cardiac function.

Introduction: Cardiac resynchronization therapy (CRT) is a proven therapeutic method in selected patients with heart failure and systolic dysfunction which increases left ventricular function and patient survival. We designed a study that included patients undergoing coronary artery bypass graft (CABG), with and without CRT‑defibrillator (CRT‑D) inserting and then measured its effects on these two groups. Patients and Methods: Between 2010 and 2013, we conducted a prospective cohort study on 100 coronary artery disease patients where candidate for CABG. Then based on the receiving CRT‑D, the patients were categorized in two groups; Group 1 (n = 48, with CRT‑D insertion before CABG) and Group 2 (n = 52 without receiving CRT‑D). Thereafter both of these groups were followed‑up at 1–3 months after CABG for mortality, hospitalization, atrial fibrillation (AF), echocardiographic assessment, and New York Heart Association (NYHA) class level. Results: The mean age of participants in Group 1 (48 male) and in Group 2 (52 male) was 58 ± 13 and 57 ± 12 respectively. Difference between Groups 1 and 2 in cases of mean left ventricular ejection fraction (LVEF) changes and NYHA class level was significant (P > 0.05). Hospitalization (P = 0.008), mortality rate (P = 0.007), and AF were significantly different between these two groups. Conclusions: The results showed that the increase in LVEF and patient’s improvement according to NYHA‑class was significant in the first group, and readmission, mortality rate and AF was increased significantly in the second group.

Comportamento da função cardíaca em fetos de mães portadoras de HIV / Bahavior of cardiac function in fetuses of mothers with HIV

Introdução: São bastante conhecidas as alterações provocadas pelo vírus HIV no coração de adultos e crianças, porém, em fetos, há poucos estudos a respeito. Considerando que a transmissão vertical é tardia e que a terapia antirretroviral oferece proteção efetiva, a função cardíaca fetal pode não estar alterada, o que não foi ainda demonstrado. Objetivos: Testar a hipótese de que não existe diferença nos parâmetros das funções sistólica e diastólica dos fetos, cujas mães são portadoras do vírus HIV, se comparados com aqueles de mães não infectadas. Métodos: Foi realizado estudo transversal, o qual incluiu 34 fetos, com idades gestacionais de 20 semanas até o termo, divididos em 2 grupos: 17 fetos de mães portadoras do vírus HIV e 17 fetos de mães livres da infecção. Foram avaliados a fração de encurtamento circunferencial do ventrículo esquerdo, o índice de pulsatilidade no ducto venoso, o índice de pulsatilidade nas veias pulmonares, a fração de encurtamento do átrio esquerdo e a relação E/A mitral. Resultados: A fração de encurtamento circunferencial (delta D) foi de 1,928% mais ou menos 0,22% nos fetos de mães HIV positivo, e de 2,55% mais ou menos 0,34% (p=0,32), naqueles fetos de mães livres da doença. O índice de pulsatilidade do ducto venoso, em fetos de mães HIV positivo, foi de 0,64 mais ou menos 0,29 e naqueles de mães livres da doença...

Controle autonômico da frequência cardíaca de pacientes com doenças cardiorrespiratórias crônicas e indivíduos saudáveis em repouso e durante a manobra de acentuação da arritmia sinusal respiratória / Autonomic control of heart rate in patients with chronic cardiorespiratory disease and in healthy participants at rest and during a respiratory sinus arrhythmia maneuver

OBJETIVO: Avaliar a modulação autonômica da frequência cardíaca (FC) em repouso, na postura supina e durante a manobra de acentuação da arritmia sinusal respiratória (M-ASR) de pacientes com doença pulmonar obstrutiva crônica (DPOC) ou com insuficiência cardíaca crônica (ICC). MÉTODOS: Vinte e oito homens foram subdivididos em três grupos: 10 com DPOC (GD) e 69±9 anos; 9 com ICC (GI) e 62±8 anos; e 9 saudáveis (GC) com 64±5 anos. Em repouso, os intervalos R-R a partir do sinal eletrocardiográfico foram obtidos nas seguintes situações: 1) 15 minutos na posição supina e 2) 4 minutos durante M-ASR na posição supina. Os dados foram analisados nos domínios do tempo (índices RMSSD e SDNN) e da frequência. Durante M-ASR, foram calculadas a razão expiração/inspiração (E/I) e a diferença inspiração/expiração (∆IE). RESULTADOS: Os principais achados mostraram que os pacientes com ICC apresentaram menores valores de RMSSD (12,2±2,6 vs 20,4±6,5), BFab (99,2±72,7 vs 305,3±208,9) e AFun (53,4±29,9 vs 178,9±113,1) quando comparados ao controle. Além disso, a banda de BFab foi significantemente reduzida no grupo DPOC quando comparado ao controle (133,8±145,5 vs 305,3±208,9). Adicionalmente, pacientes com ICC e DPOC mostraram menor razão E/I (1,1±0,06 vs 1,2±0,1 e 1,1±0,03 vs 1,2±0,1) e ∆IE (7,0±3,5 vs 12,7±0,1 e 4,9±1,6 vs 12,7±0,1), respectivamente, comparados ao GC durante a M-ASR. CONCLUSÃO: Os resultados deste estudo sugerem que tanto a DPOC como a ICC produzem impacto negativo sobre o controle autonômico da FC.

OBJECTIVE: To evaluate the autonomic modulation of heart rate (HR) at rest in the supine position and during a respiratory sinus arrhythmia maneuver (M-RSA) among participants with chronic obstructive pulmonary disease (COPD) or with chronic heart failure (CHF). METHODS: Twenty-eight men were divided into three groups: ten with COPD, aged 69±9 years; nine with CHF, aged 62±8 years; and nine healthy participants aged 64±5 years (controls). At rest, the R-R interval of the electrocardiographic signal was obtained in the following situations: 1) 15 min in the supine position; and 2) 4 min during M-RSA in the supine position. The data were analyzed in the time domain (RMSSD and SDNN indices) and the frequency domain (LFab and HFab). During M-RSA, the expiratory/inspiratory ratio (E/I) and the inspiratory/expiratory difference (∆IE) were calculated. RESULTS: The main findings showed that the CHF patients presented lower RMSSD (12.2±2.6 vs. 20.4±6.5), LFab (99.2±72.7 vs. 305.3±208.9) and HFab (53.4±29.9 vs. 178.9±113.1), compared with the controls. The LFab band was significantly lower in the COPD group than in the controls (133.8±145.5 vs. 305.3±208.9). Additionally, both CHF patients and COPD patients showed lower E/I ratios (1.1±0.06 vs. 1.2±0.1 and 1.1±0.03 vs. 1.2±0.1) and ∆IE values (7.0±3.5 vs. 12.7±0.1 and 4.9±1.6 vs. 12.7±0.1), respectively, compared with the controls during M-RSA. CONCLUSION: The results from this study suggest that both COPD and CHF have a negative impact on the autonomic control of heart rate.

Análise comparativa de desempenho das transformadas Wavelet e Hilbert na detecção do QRS em ECG / Performance comparison analysis of Wavelet and Hilbert transforms for QRS detection in ECG

O processo de detecção do complexo QRS é o primeiro passo de um processo de extração de parâmetros do sinal eletrocardiograma (ECG) em sistemas de auxílio ao diagnóstico médico. O presente trabalho apresenta resultados detalhados de comparação da aplicação de duas transformadas matemáticas, Wavelet e Hilbert, em um algoritmo de detecção de QRS em termos de taxas de detecções corretas (sensibilidade e preditividade positiva) e de uma medida de frequência de recorrência a processos de filtragem (pré-processamento). Uma abordagem inovadora é implementada, na qual as rotinas de filtragem são inseridas dentro do estágio de decisão, ou seja, é realizada a supressão da etapa de pré-processamento. As transformadas são aplicadas no algoritmo, que é baseado em um limiar adaptativo, com o objetivo de realçar, apenas quando necessário, os picos (pontos fiduciais)do QRS. Em uma primeira abordagem, apenas a transformada Wavelet é utilizada neste realce e, numa segunda abordagem, a transformada de Hilbert é inserida em série à aplicação da Wavelet em dois possíveis arranjos. São realizados experimentos dos algoritmos sobre os exames da base de dados Arrhythmia Database, pertencente ao conjunto de bases de dados do MIT-BIH. É composta por 48 gravações de ECG com duração de trinta minutos, amostrados a uma frequência de 360 Hz com resolução de 4,88 μV sobre uma faixa de variação de 10 mV. Ao todo, contabilizam-se 109.662 complexos QRS. Taxas de 98,85% de sensibilidade e 95,10% de preditividade positiva são obtidas com a aplicação exclusiva da transformada Wavelet, enquanto que 98,89% de sensibilidade e 98,52% de preditividade positiva são obtidas com aaplicação em série das transformadas Wavelet e de Hilbert.

The process of QRS detection is the first stage of a greater process: the feature extraction in the electrocardiogram (ECG). This work presents detailed results on the performance of two mathematical transforms, Hilbert and Wavelet, which are applied in QRS detection. The evaluation parameters are the detection rates and a measure of frequency of recurrence to filtering processes. An innovative approach is implemented: the filtering routines are inserted in the decision stage, i.e. the preprocessing stage is removed. The algorithm is based on adaptive threshold technique and the two transforms are applied in order to emphasize, only when necessary, the QRS fiducial points. In a first approach, only the Wavelet transform is applied, and in a second approach, the Hilbert transform is inserted before the Wavelet transform or after it. We evaluate these approaches on the well-known MIT-BIH Arrhythmia Database. It contains 48 half-hour recordings of annotated ECG with a sampling rate of 360 Hz and 4.88 μV resolution over a 10 mV range, totalizing 109,662 QRS complexes. Sensitivity rates of 98.85% and 98.89% are respectively attained when the Wavelet transform is applied in the filtering processes and both Hilbert and Wavelet transforms are applied. Predictability rates of 95.10% and 98.52% are also attained respectively using Wavelet transform and the simultaneous application of Hilbert and Wavelet transforms in the filtering processes.

Pruebas de provocación de isquemia en el estudio de la cardiopatía coronaria / Tests for detecting coronary artery disease

Se revisan las indicaciones más apropiadas de las pruebas de provocación de isquemia miocárdica, subrayando el concepto de que su mayor utilidad se encuentra en el grupo de pacientes con probabilidad intermedia de enfermedad coronaria. Se analizan las pruebas comúnmente empleadas para este fin: prueba de esfuerzo (PE), cintigrafía miocárdica SPECT (SPECT) y ecocardiografía de estrés (EDE), detallando qué subgrupos de pacientes se benefician más de cada una. El subgrupo constituido por mujeres, aunque presentan PE más equívocas, también puede ser estudiado inicialmente con PE. Se destaca que en pacientes capaces de ejercitarse y sin alteraciones en el electrocardiograma basal (ECG basal), la prueba de elección es PE. En aquéllos capaces de ejercitarse, pero con alteraciones significativas del ECG basal, es necesario recurrir a EDE (idealmente con ejercicio) o SPECT con ejercicio. Una excepción a esta norma, es el paciente capaz de ejercitarse pero cuyo ECG basal muestra bloqueo completo de rama izquierda del haz de His; en este caso está indicado un estresor vasodilatador. En enfermos incapaces de ejercitarse, debe recurrirse a pruebas de provocación con imágenes y estresores farmacológicos. La decisión de elegir entre EDE o SPECT, está determinada por la experiencia de cada institución, ya que ambas poseen rendimientos diagnósticos similares.

This article reviews the most appropriate indications of tests for detecting coronary artery disease, emphazising the concept that its greater benefit is in the group of patients with intermediate probability of disease. The commonly used tests for this aim are analyzed: exercise stress testing (ET), SPECT myocardial perfusion imaging (SPECT) and stress echocardiography (SE), indicating what sub - groups of patients benefit more from each. The sub - group of women, although displays more ambiguous ET, also can be studied initially with ET. It is pointed out that in patients able to exercise themselves and without alterations of their baseline electrocardiograms (bEKG), the test of election is ET. In those patients able to exercise themselves, but with significant alterations on their bEKG, it is necessary to carry out SE or SPECT, being used in both cases exercise like stressor. An exception to this rule, is the patient able to exercise but whose bEKG shows a left bundle branch block; in this case, a vasodilator stressor is indicated. In patients unable to exercise themselves, imaging tests with pharmacological stressors should be performed. The decision to carry out SE or SPECT, is determined by intitutions' experience, since both techniques yield similar diagnostic accuracy.

Effectiveness of 99mTc-tetrofosmin for assessment of heart functions in micropigs

This study examined the suitability of a nuclear imagingtechnique using 99mTc-tetrofosmin as an agent to assess theheart functions of healthy micropigs. The mean age of thepigs was 360 days (male), and the mean body weight was35.3kg ranging from 34.5-36kg. There were no significantperfusion defects in any of the reconstructed images.Gated single-photon emission computed tomographyimaging can be used to calculate the ventricular volumeand ejection fraction (EF). In this case, an EF of 79% wascalculated from the ventricular volume of the end-systolicimage (10 ml) subtracted from that of the end-diastolicvolume (49 ml). A perfusion defect (particularly the apex,lateral wall) is unlikely because of the presence of apreserved wall motion in a segment with a defect. It isconcluded that quantitative cardiac scintigraphy, using99mTc-tetrofosmin is an adequate technique for estimatingthe heart functions of healthy micropigs.

Reparación del miocardio mediante la terapia con células madre / Myocardial repair with bone marrow stem cell therapy

Para evaluar la efectividad del transplante de células madre en pacientes con infarto del miocardio e insuficiencia cardíaca crónica severa mediante técnicas de cardiología nuclear, se estudiaron 15 pacientes revascularizados: nueve (grupo I) recibieron células madre autólogas de médula ósea. Los 6 restantes correspondieron al grupo II (controles). Se les realizó evaluación clínica, ventriculografía radioisotópica y gammagrafía de perfusión con SPECT-gatillado (tecnecio-99m MIBI; protocolo de dos días: dipiridamol – reposo), antes y tres meses después del proceder. A los tres meses hubo mejoría clínica en el 89 por ciento de los pacientes del grupo I. La fracción de eyección de ventrículo izquierdo aumentó: de 32±9 por ciento a 44±13 por ciento (p=0.03; grupo I) y de 38±2 por ciento a 48±14 por ciento (p NS; grupo II). La velocidad máxima de llenado se incrementó de 120±11 a 196±45 VTD/seg (p=0.03; grupo I). El score sumado del dipiridamol disminuyó significativamente sólo en el grupo I (de 35±5 a 23±14; p=0.02). La mejoría de la perfusión estuvo relacionada con el sitio de implante en el 60 por ciento de los casos. Concluimos que el transplante de células madre de médula ósea es efectivo en pacientes con insuficiencia cardíaca crónica severa de etiología isquémica.

Influência da idade gestacional no índice de desempenho miocárdico (índice de Tei) do ventrículo esquerdo em fetos com coração normal / Influênce of gestacional age on the left ventricular doppler index of myocardial performance (Tei Index) in fetuses normal heart

Avaliar a influência da idade gestacional (IG) no índice de Tei do ventrículo esquerdo em fetos com coração normal. Métodos: 49 fetos divididos em 3 grupos de IG (média mais ou menos desvio padrão)foram avaliados por Doppler ecocardiografia, obtendo-se as velocidades do fluxo transvalvar mitral e os intervalos: tempo de relaxamento isovolumetrico (TRIV) tempo de contração isovolumétrico(TCIV), e tempo de ejeção aórtico(TEJ). O índice de Tei foi calculado pela formula: (TCIV mais TRIV)/TE. Análise de variância foi usada para comparar os valores do índice e seus componentes entre os grupos. Regressão linear simples avaliou a relação entre IG e o índice Tei. Resultados: Houve aumento gradativo do índice de Tei com a IG (0,39 mais ou menos 0,02 versus 0,44 mais ou menos 0,02 versus 0,48 mais ou menos 0,02, p menos 0,01), devido a uma progressiva diminuição do Tej (189 mais ou menos 3 ms versus 185 mais ou menos 2 versus 172 mais ou menos 4 ms, p menos 0,05).Não houve diferenças entre os grupos quanto ao TRIV, TCIV, E, A, E/A e frequência cardíaca. O índice de Tei e o Tej tiveram uma correlação linear com a IG (r igual 0,38, p menos 0,01 e r igual 0,24, p 0,05, respectivamente), o que não aconteceu com a TRIV e TCIV (p igual ns). Conclusão: A IG parece ter uma pequena, porém significante, influência na determinação do índice de Tei, que aumenta conforme a gestação se aproxima do termo.

Testes preditores de risco cirúrgico: qual o melhor? / Surgical risk predictor tests: which one is the best?

Introdução: O consumo máximo de oxigênio ao exercício (VO2máx) constitui o padrão-ouro para predizer o risco cirúrgico, mas raros são os serviços que possuem um ergoespirômetro para exames de rotina. A espirometria é um exame acessível e muito utilizado no pré-operatório, contudo limita-se a mostrar alterações ventilatórias do indivíduo em repouso. Testes mais simples, como subir escada ou caminhar no plano, também podem predizer o risco cirúrgico, porém são pouco usados, apesar de avaliarem a capacidade física do indivíduo. Como os dois últimos testes são mais baratos e podem ser realizados em quaisquer hospitais, testamos sua acurácia e a do teste espirométrico para determinar qual o melhor, tendo como padrão-ouro o VO2máx. Objetivos: Determinar dentre os quatro testes (tempo de escada, potência de escada, teste de caminhada e VEF1) o de melhor acurácia, utilizando o VO2máx como padrão-ouro. Método: A espirometria (VEF1) foi realizada em espirômetro Méd-Graphics Pulmonary Function System1070 de acordo com as normas da ATS. O teste de caminhada de 6 minutos (TC6) foi realizado em passo rápido, com incentivo, em corredor plano de 120m de extensão, à sombra, medindo-se a distância (d) percorrida em 6 minutos. O teste de escada (TE) foi realizado com incentivo, em escada à sombra, composta de 72 degraus, com 6 lances e 12 degraus por lance, cada degrau medindo 16,9 cm, num total de 12,16 m de altura; o tempo (t) foi cronometrado, e a potência (P) calculada mediante a fórmula: P=m.g.h./t. A ergoespirometria (VO2máx) foi realizada em ergoespirômetro Quinton 4500 utilizando o protocolo de Balke. Foi calculada a correlação linear de Pearson (r) entre variáveis e seus respectivos valores de p, além da sensibilidade, especificidade e acurácia dos quatro testes, valendo-se do VO2máx como padrão-ouro. A estatística Kappa (K) foi utilizada para estudo da concordância pobre; de 0,21 a 0,4, regular; de 0,41 a 0,6, moderada; de 0,61 a 0,8 boa e de 0,81 a 1,0, muito boa...

Relação entre o índice de performance miocárdica e parâmetros de função ventricular esquerda em ratas com infarto do miocárdio / Relationship between noninvasive doppler-derived myocardial performance index with left ventricular function parameters in rats with myocardial infarction

O índice performance miocárdica (IPM) tem sido objeto de vários estudos. É considerado um índice de função ventricular global por utilizar parâmetros de função sistólica e diastólica. Todavia, não há estudos, pela ecocardiografia Doppler (eco-D), demonstrando a importância e o impacto das variáveis convencionais das funções sistólica e diastólica no IPM. Objetivo: analisar a relação entre as variáveis convencionais das funções sistólica e diastólica do ventrículo esquerdo como IPM avaliado por eco-D num modelo experimental de infarto de miocárdio em ratas...

Evaluation of cardiac performance in hemodynamically unstable patients with septic shock

Septic shock is characterized by bi-ventricular dysfunction within the first 24 hours after its onset due to circulating mediators, myocardial ischemia and micorvascular dysfunction. The aim of this study was to assess the cardiac functions in patients with septic shock and the prognostic effect of its derangement. Eighteen patients with septic shock were studied at the Critical Medicine Department at Alexandria, Main University hospital. Clinical evaluation of the severity of illness was done using the Simplified Acute Physiology Score, as well as hemodynamic assessment by Swan-Ganz catheter and echocardiography on admission, after 24 and 48 hours. All patients were put on Dobutamine and Dopamine infusions on admission. If shock persisted, adrenaline was infused. The ejection fraction decreased in all patients, and was paradoxically lower in those who survived. The total peripheral resistance increased with treatment in patients who finally survived, but continued to diminish in non-survivors. The changes in stroke volume, cardiac output and cardiac index with treatment were insignificant in both groups. After 24 hours, 14 patients did not respond to treatment with significant diminution in the peripheral resistance. Cardiac dysfunction in septic shock is characterized by peripheral vasodilatation and impaired global performance. This transient vasodilatation may be an adaptive mechanism to maintain cardiac output. The left ventricular ejection fraction is depressed in the initial phase of septic shock, and is more markedly depressed in patients who ultimately will recover. An increasing systemic vascular resistance during the course of septic shock is an important marker in the improvement of survival rate

A comparative analysis of preprocessing techniques of cardiac event series for the study of heart rhythm variability using simulated signals

In the present study, using noise-free simulated signals, we performed a comparative examination of several preprocessing techniques that are used to transform the cardiac event series in a regularly sampled time series, appropriate for spectral analysis of heart rhythm variability (HRV). First, a group of noise-free simulated point event series, which represents a time series of heartbeats, was generated by an integral pulse frequency modulation model. In order to evaluate the performance of the preprocessing methods, the differences between the spectra of the preprocessed simulated signals and the true spectrum (spectrum of the model input modulating signals) were surveyed by visual analysis and by contrasting merit indices. It is desired that estimated spectra match the true spectrum as close as possible, showing a minimum of harmonic components and other artifacts. The merit indices proposed to quantify these mismatches were the leakage rate, defined as a measure of leakage components (located outside some narrow windows centered at frequencies of model input modulating signals) with respect to the whole spectral components, and the numbers of leakage components with amplitudes greater than 1 percent, 5 percent and 10 percent of the total spectral components. Our data, obtained from a noise-free simulation, indicate that the utilization of heart rate values instead of heart period values in the derivation of signals representative of heart rhythm results in more accurate spectra. Furthermore, our data support the efficiency of the widely used preprocessing technique based on the convolution of inverse interval function values with a rectangular window, and suggest the preprocessing technique based on a cubic polynomial interpolation of inverse interval function values and succeeding spectral analysis as another efficient and fast method for the analysis of HRV signals.

Trasplante hepático: evaluación preoperatoria / Preoperative assessment of candidates for liver transplant

Candidates for hepatic transplant requiere a careful identification of risk factors present in the preoperative period. Child C patients have a higher incidence of renal function derangement, septic complications and mortality than Child A or B patients. Alterations in cardiovascular, renal respiratory and neurologic systems, that sometimes constitute clearly defined syndromes, have important prognostic implications. These alterations shed doubts on the moment and indications for transplantation and on the correct preoperative management of these patients

Evaluación del sistema nervioso autónomo en pacientes con síncope neurocardiogénico durante el Tilt test: aporte del análisis de la variabilidad del intervalo R-R / Evaluation of the autonomic nervous system during Tilt test in patients with neurocardiogenic syncope: analysis of R-R variability

En 32 pacientes consecutivos con síncope de etiología no precisada, estudiamos el sistema nervioso autónomo durante el tilt test (TT) con isoproterenol mediante el análisis de la variabilidad del intervalo RR (VRR) y análisis de variables temporales (11 pacientes con TT+ y 21 pacientes con TT-). Se midió el intervalo entre 2 ondas R sucesivas (RR), la desviación standard de todos los intervalos RR en 5 minutos (SDNN), la raíz cuadrada de las diferencias sucesivas (rMSSD) y el porcentaje de diferencias entre intervalos RR normales adyacentes mayores de 50 msegs (pNN50). Basalmente los 4 parámetros de la VRR analizados fueron similares en ambos grupos. Después de ISO, en el grupo con TT- se observó disminución significativa de la RR, de la rMSSD y del pNN50, sin cambios de la SDNN. En los 11 sujetos con TT+ después de ISO, se observó un descenso significativo de la RR, para luego a 70º, en el momento del síncope o presíncope, experimentar un leve aumento, pero siempre en un nivel más bajo que en la fase basal. El hecho más relevante en este grupo fue el ascenso importante de la SDNN al momento del síncope o presíncope. Los índice de actividad parasimpática, análisis de la VRR nos ha permitido caracterizar indirectamente el comportamiento del SNA durante el TT, documentándose activación exagerada de la actividad vagal en pacientes con síncope neurocardiogénico. Esta metodología puede mejorar la caracterización del SNA de los pacientes con distintos tipos de síncope y además evaluar diferentes intervenciones terapeúticas

Effects of mitral balloon valvuloplasty on left ventricular systolic function in patients with isolated tight mitral stenosis

With the advent of mitral balloon valvuloplasty [MBV] in 1984 it became the treatment of choice in well selected patients with mitral stenosis [MS]. This study aimed to find out the effects of MBV on LV systolic performance immediately after the procedure and on short-tern follow-up. Twenty-five patients with severe MS were included in this study [mitral valve area [MVA] of 0.9 +/- 0.14 cm2 and mean transmitral diastolic pressure gradient of 15.5 +/- 5.3 mmHg]. Double balloon MBV technique was used in 88% of these and single balloon MBV technique in the remaining 12%. Patients were evaluated on follow-up by echo Doppler study using Simpson's rule to assess LVEF% as index of LV systolic performance. The mean period of follow-up was 7 +/- 1.7 months. No major complications were found. Increase in the severity of MR by 1 grade or the development of new MR has been developed in 8 patients and regressed on follow-up. ASD was encountered in 5 patients and disappeared by the 3rd month of follow-up. Optimal results were achieved in 22 patients [MVA post MBV > 1.5 cm2] and 3 patients had MVA post MBV < 1.5 cm2. Restenosis developed in 3 patients during the follow-up period and mitral valve replacement [MVR] was offered to them. Subjective improvement by at least 1 NYHA [New York Heart Association classification for Congestive Heart Disease] class in the patient's functional status was observed as early as the first day post MBV which was maintained on follow-up. After MBV, the MVA increased to 1.98 +/- 0.33 cm2 [P < 0.0001] and the pressure gradient dropped to 5.5 +/- 1.6 mmHg [P < 0.0001] and these results were maintained with no significant changes over the period of follow-up. LVEF improved significantly immediately after MBV [p < 0.0001] to 60.6 +/- 5.7% and further significant improvement as noted after 6 months of follow-up [P < 0.05] to 62.7 +/- 6.5%. This functional improvement in LV systolic performance was unaffected by the unwanted sequelae of MBV or the severity of MV morphological abnormalities. It was fair to conclude that in appropriate patients, in skilled and experienced centres, MBV is the procedure of first choice for relief of severe MS and this is associated with immediate as well as short-term improvement in subjective symptoms and LV systolic performance