Fisiología respiratoria: circulación pulmonar / Respiratory physiology: pulmonary circulation

El pulmón recibe sangre desde la circulación bronquial y pulmonar. La circulación pulmonar presenta importantes diferencias con la sistémica, sus vasos sanguíneos poseen características únicas que le permiten cumplir sus diferentes funciones, siendo la más importante el intercambio gaseoso. Existen múltiples factores, activos y pasivos, que están involucrados en la regulación de la resistencia vascular y flujo sanguíneo pulmonar.

The lung receives blood from the bronchial and the pulmonary circulation. The pulmonary circulation presents important differences with the systemic circulation, its blood vessels have unique characteristics that allow them to fulfill their different functions, the most important being gas exchange. There are multiple factors, active and passive, that are involved in the regulation of vascular resistance and pulmonary blood flow.

Caracterización de parámetros del intercambio gaseoso en la Ciudad de México / Characterization of gas exchange parameters in Mexico City

Introducción: en las grandes altitudes, el intercambio gaseoso suele estar deteriorado; en la altitud moderada de la Ciudad de México esto no está aún plenamente definido. Objetivo: caracterizar el intercambio gaseoso en la altitud moderada de la Ciudad de México. Material y métodos: mediante un estudio transversal analítico se estudiaron sujetos nacidos y habitantes de la Ciudad de México, de ambos géneros, con edades de 20 a 59 años sin enfermedad cardiopulmonar. Se registraron sus variables demográficas, espirometría simple y de gasometría arterial. Las diferencias en las variables se calcularon con ANOVA de una vía para grupos independientes y ajuste de Bonferroni. Una p < 0.05 se aceptó como significativa. Resultados: se estudiaron 335 sujetos, de los cuales 168 (50.15%) fueron hombres, la edad grupal fue de 45 ± 11 años, con índice de masa corporal 22.97 ± 1.54 Kg/m2. La relación volumen espiratorio forzado en el primer segundo/Capacidad vital forzada (VEF1/CVF) de 91.58 ± 12.86%. La presión arterial de oxígeno fue de 66 ± 5.02 mmHg, el bióxido de carbono: 32.07 ± 2.66 mmHg, la saturación arterial de oxígeno: 93.03 ± 1.80% y la hemoglobina: 14.07 ± 1.52 gr/dL. Conclusiones: la presión arterial de oxígeno y del bióxido de carbono están disminuidos a la altura de la Ciudad de México.

Background: At high altitude the gas exchange is impaired, in the moderate altitude of Mexico City they are not yet defined. Objective: To characterize the gas exchange in the moderate altitude of Mexico City. Material and methods: Through an analytical cross-sectional study, subjects born and inhabitants of Mexico City, both genders, aged 20 to 59 years without cardiopulmonary disease, were studied. Their demographic variables, simple spirometry and arterial blood gas were recorded. Differences in variables were calculated with one-way ANOVA for independent groups and Bonferroni adjustment. p < 0.05 was accepted as significant. Results: 335 subjects were studied, 168 (50.15%) men. Group age 45 ± 11 years old, body mass index 22.97 ± 1.54 Kg/m2. Forced expiratory volume ratio in the first second / Forced vital capacity (FEV1/FVC) 91.58 ± 12.86%. The arterial oxygen pressure was: 66 ± 5.02 mmHg, carbon dioxide: 32.07 ± 2.66 mmHg, arterial oxygen saturation: 93.0 3 ± 1.80%, and hemoglobin: 14.07 ± 1.52 gr/dL. Conclusions: The arterial oxygen pressure and carbon dioxide are lowered at the Mexico City altitude.

Pulmonary Hypertension in General Cardiology Practice / Hipertensão Pulmonar na Prática do Cardiologista

Abstract The finding of pulmonary hypertension (PH) by echocardiography is common and of concern. However, echocardiography is just a suggestive and non-diagnostic assessment of PH. When direct involvement of pulmonary circulation is suspected, invasive hemodynamic monitoring is recommended to establish the diagnosis. This assessent provides, in addition to the diagnostic confirmation, the correct identification of the vascular territory predominantly involved (arterial pulmonary or postcapillary). Treatment with specific medication for PH (phosphodiesterase type 5 inhibitors, endothelin receptor antagonists and prostacyclin analogues) has been proven effective in patients with pulmonary arterial hypertension, but its use in patients with PH due to left heart disease can even be damaging. In this review, we discuss the diagnosis criteria, how etiological investigation should be carried out, the clinical classification and, finally, the therapeutic recommendations for PH.

Resumo O achado de hipertensão pulmonar (HP) em avaliação ecocardiográfica é frequente e preocupante. No entanto, o ecocardiograma é apenas um exame sugestivo e não diagnóstico de HP. Quando se suspeita de acometimento direto da circulação pulmonar, está indicada medida hemodinâmica invasiva para estabelecer o diagnóstico. Essa avaliação permite, além da confirmação diagnóstica, a correta identificação do território vascular predominantemente acometido (arterial pulmonar ou pós-capilar). O tratamento com as medicações específicas de HP (inibidores da fosfodiestarese 5, antagonistas do receptor de endotelina, análogos da prostaciclina e estimulador da guanilil ciclase solúvel) é comprovadamente eficaz para pacientes com hipertensão arterial pulmonar, mas seu uso em pacientes com HP decorrente de doença cardíaca de câmaras esquerdas pode até mesmo ser prejudicial. Discutiremos nesta revisão o critério diagnóstico, a maneira de proceder a investigação etiológica, a classificação clínica e, finalmente, as recomendações terapêuticas na HP.

Valoración de ecuaciones derivadas del flujo pulmonar y regurgitación tricuspídea: utilidad en el test de vasoreactividad pulmonar / Valuation of equations derived from Pulmonary Flow and Tricuspid Regurgitation: usefulness in Pulmonary Vasoreactivity Testing

RESUMEN: Antecedentes: La presión media arterial pulmonar (PMAP) es una variable hemodinámica indispensable para el diagnóstico, clasificación y pronóstico de la Hipertensión Pulmonar (HP). Su cuantificación se realiza en forma invasiva por cateterismo cardíaco derecho (CCD) y no invasivamente por ecocardiografía Doppler. Masuyama propuso su medición mediante el gradiente transvalvular pulmonar diastólico derivado de la velocidad máxima inicial de la regurgitación pulmonar (∆RPi2) correspondiendo cercanamente a la medición invasiva. Objetivos: Revalidar 3 métodos ecocardiográficos que estiman la PMAP y valorar la utilidad del método de Chemla en el Test de Reactividad Vascular Pulmonar (TRVP). Métodos: Estudio prospectivo, observacional, doble ciego divido en dos etapas. A) o I) 30 pacientes se realizó ecocardiografía Doppler diagnóstica en nuestro centro. Se midieron regurgitación tricuspídea (RT) y tiempo de aceleración pulmonar (TAP) para derivar las siguientes ecuaciones: 1) 0.61xPSAP+1.95 (Chemla) 2) Gradiente presión media RT (∆PmRT) +PAD (presión-aurícula derecha) (Aduen) y 3) 79-0.45xTAP o 90-0.60xTAP, según sea el valor del TAP. B) o II) 10 pacientes enrolados para realizar el TRVP comparando la medición ecocardiográfica (Chemla) con CCD. Resultados: En la primera parte del estudio se encontró alta correlación entre las 3 ecuaciones: ChemlaAduen, R2=0.91; Chemla-Kitabatake, R2=0.87; Aduen-Kitabatake, R2=0,91. En la segunda parte comparando la PMAP-Chemla y Cateterismo derecho (CD) obtuvimos alta correlación: en tiempo 0, 30 min y recuperación:(R2=0.87, 0.99, 0.98, respectivamente). Ambas partes del estudio mostraron límites de concordancia satisfactoria con valor medio de la diferencia entre los métodos cercano a 1 en el t30 y tR del TRVP. Conclusión: los métodos dependientes de la medición de la RT son efectivos y confiables para estimar la PMAP. El método de Chemla es útil en el TRVP.

ABSTRACTS: Background: Mean Pulmonary arterial pressure (PMAP)is an indispensable hemodynamic variable for the diagnosis, classification and prognosis of Pulmonary Hypertension (PH). Its quantification is performed invasively by cardiac catheterization and non-invasively by Doppler echocardiography. Masuyama proposed its measurement by the transvalvular diastolic pulmonary gradient derived from the initial maximum velocity of pulmonary regurgitation(ΔPRi2) corresponding closely to the invasive measurement. Objectives: to compare 3 known echocardiographic methods to estimate MPAP and demonstrate the usefulness of the Chemla method in the Pulmonary Vascular Reactivity Test (PVRT). Methods: prospective, observational, double-blind study divided into two stages. A) 30 patients underwent diagnostic Doppler echocardiography. Tricuspid regurgitation (TR) and pulmonary acceleration time (PAT) were measured to derive the equations: 1) 0.61xSPAP + 1.95 (Chemla) 2) Gradient mean pressure TR (ΔPmTR) + RAP (right atrium pressure) (Aduen).3) 79-0.45xPAT o 90-0.60xPAT depending on the value of PAT. B) 10 patients enrolled to PVRT comparing the echocardiographic measurement (Chemla) with right catheterization. Results: in the first part of the study a high correlation between the 3 equations was found : ChemlaAduen, R2 = 0.91; Chemla-Kitabatake, R2=0.87; Aduen-Kitabatake, R2=0.91. In the second part comparing the MPAP-Chemla and RHC we obtained a high correlation in time 0, 30 min and recovery: (R2=0.87,0,99,0.98, respectively). Both parts of the study showed satisfactory limits concordance with mean value of the difference between the methods close to 1 in the t30 and tR of the TRVP. Conclusion: the methods dependent on the measurement of the TR are effective and reliable for estimating MPAP. The Chemla method is useful in the PVRT.

Sequestro pulmonar e tratamento endovascular: um relato de caso / Pulmonary sequestration and endovascular treatment: a case report

O sequestro pulmonar refere-se à anomalia congênita definida por massa de parênquima pulmonar não funcionante. É dividido pela existência de envoltório pleural próprio em intralobar, representando cerca de 75% dos casos, ou extralobar, responsável pelos 25% restantes. O diagnóstico é feito através de radiografia e confirmado com tomografia computadorizada, ressonância nuclear magnética e arteriografia. Tradicionalmente, o tratamento proposto é cirúrgico, mas a técnica endovascular tem apresentado bons resultados. É relatado o caso de uma mulher, 29 anos, com quadro clínico de pneumonias de repetição desde os 5 anos. A tomografia de tórax revelou malformação vascular em região inferior de pulmão direito. O tratamento vascular foi realizado através de embolização do ramo anômalo

Pulmonary sequestration is a congenital anomaly defined as a nonfunctioning mass of lung parenchyma. Presence of an independent pleural envelope classifies it as intralobar, accounting for approximately 75% of the cases, while absence classifies cases as extralobar, accounting for the remaining 25%. Diagnosis is made through radiography and confirmed by computed tomography, magnetic resonance, or angiography. The traditional treatment is open surgical repair, but endovascular techniques have been used, with good results. We report the case of a 29-year-old-woman presenting with recurrent pneumonia for 5 years. A CT scan of the chest revealed poor vascular formation in the lower region of the right lung. The pulmonary sequestration was treated by embolization of the anomalous branch

Are high flow arteriovenous accesses associated with worse haemodialysis? / Acessos arteriovenosos de alto débito estão associados a pior hemodiálise?

ABSTRACT Introduction: An arteriovenous (AV) access flow (Qa) of 400 mL/min is usually sufficient for an effective hemodialysis (HD), but some accesses continue developing and become high flow accesses (HFA). Some authors postulated that an HFA might shift a significant portion of dialyzed blood from the cardiac output, which could decrease HD efficiency and lead to volume overload. Objective: The aim of our study was to evaluate if HFA is associated with reduced HD efficiency and/or volume overload in prevalent HD patients. Methods: We performed a 1-year retrospective study and assessed HD efficiency by the percentage of sessions in which the Kt/V > 1.4 and volume overload by bioimpedance spectroscopy. Results: The study included 304 prevalent HD patients with a mean age of 67.5 years; 62.5% were males, 36.2% were diabetics, with a median HD vintage of 48 months. Sixteen percent of the patients had a HFA (defined as Qa > 2 L/min). In multivariate analysis, patients with HFA presented higher risk of volume overload (OR = 2.67, 95%CI = 1.06-6.71) and severe volume overload (OR = 4.06, 95%CI = 1.01-16.39) and attained dry weight less frequently (OR = 0.37, 95%CI = 0.14-0.94). However, HFA was not associated with lower Kt/V. Conclusion: Our results suggest that patients with HFA have higher risk of volume overload. However, contrarily to what has been postulated, HFA was not associated with less efficient dialysis, measured by Kt/V. Randomized controlled trials are needed to clarify these questions.

RESUMO Introdução: Um débito de sangue de acesso arteriovenoso (AV) (Qa) de 400 mL/min é geralmente suficiente para uma hemodiálise (HD) eficaz, mas alguns acessos continuam se desenvolvendo e se tornam acessos de alto débito (AAD). Alguns autores postularam que um AAD poderia desviar uma porção significativa do sangue dialisado do débito cardíaco, o que poderia diminuir a eficiência da HD e levar à sobrecarga de volume. Objetivo: O objetivo do nosso estudo foi avaliar se o AAD está associado à redução da eficiência da HD e/ou à sobrecarga de volume em pacientes prevalentes em HD. Métodos: Foi realizado um estudo retrospectivo de 1 ano, e avaliada a eficiência da HD pela porcentagem de sessões em que o Kt/V > 1,4 e a sobrecarga de volume avaliada pela bioimpedância. Resultados: O estudo incluiu 304 pacientes prevalentes em HD, com média de idade de 67,5 anos; 62,5% eram do sexo masculino; 36,2% eram diabéticos, com uma mediana de tempo em HD de 48 meses. Dezesseis por cento dos pacientes apresentavam AAD (definida como Qa > 2 L/min). Na análise multivariada, os pacientes com AAD apresentaram maior risco de sobrecarga de volume (OR = 2,67; IC95% = 1,06-6,71) e sobrecarga severa de volume (OR = 4,06; IC95% = 1,01-16,39) e atingiram o peso seco com menor frequência (OR = 0,37, IC 95% = 0,14-0,94). No entanto, o AAD não foi associado uma menor razão Kt/V. Conclusão: Nossos resultados sugerem que pacientes com AAD apresentam maior risco de sobrecarga de volume. No entanto, ao contrário do que foi postulado, o AAD não foi associado à diálise menos eficiente, medida pelo Kt/V. Ensaios clínicos randomizados são necessários para esclarecer essas questões.

Protective Effect of Right Ventricular Mitochondrial Damage by Cyclosporine A in Monocrotaline-induced Pulmonary Hypertension

BACKGROUND AND OBJECTIVES: Mitochondria play a key role in the pathophysiology of heart failure and mitochondrial permeability transition pore (MPTP) play a critical role in cell death and a critical target for cardioprotection. The aim of this study was to evaluate the protective effects of cyclosporine A (CsA), one of MPTP blockers, and morphological changes of mitochondria and MPTP related proteins in monocrotaline (MCT) induced pulmonary arterial hypertension (PAH). METHODS: Eight weeks old Sprague-Dawley rats were randomized to control, MCT (60 mg/kg) and MCT plus CsA (10 mg/kg/day) treatment groups. Four weeks later, right ventricular hypertrophy (RVH) and morphological changes of right ventricle (RV) were done. Western blot and reverse transcription polymerase chain reaction (RT-PCR) for MPTP related protein were performed. RESULTS: In electron microscopy, CsA treatment prevented MCT-induced mitochondrial disruption of RV. RVH was significantly increased in MCT group compared to that of the controls but RVH was more increased with CsA treatment. Thickened medial wall thickness of pulmonary arteriole in PAH was not changed after CsA treatment. In western blot, caspase-3 was significantly increased in MCT group, and was attenuated in CsA treatment. There were no significant differences in voltage-dependent anion channel, adenine nucleotide translocator 1 and cyclophilin D expression in western blot and RT-PCR between the 3 groups. CONCLUSIONS: CsA reduces MCT induced RV mitochondrial damage. Although, MPTP blocking does not reverse pulmonary pathology, it may reduce RV dysfunction in PAH. The results suggest that it could serve as an adjunctive therapy to PAH treatment.

Mecanismos regulatorios del tono vascular pulmonar neonatal: una perspectiva molecular / Regulatory mechanisms of neonatal pulmonary vascular tone: a molecular perspective

La adaptación al medio extrauterino incluye un aumento considerable de la PaO2, que induce especialmente cambios estructurales y vasoactivos en la circulación pulmonar, que llevarán a una circulación previamente pobremente irrigada, a recibir ∼100% del gasto cardíaco del recién nacido, permitiendo el normal intercambio gaseoso. La regulación local de la circulación arterial pulmonar neonatal basal, es mantenida por un delicado equilibrio entre agentes vasoconstrictores y vasodilatadores. Este equilibrio, permite mantener la circulación pulmonar como un territorio de gran flujo sanguíneo y baja resistencia. La acción de los vasoconstrictores permite la formación de las interacciones entre actina y la cadena liviana de la miosina, esta es inducida en la célula muscular lisa principalmente por dos vías: a) dependiente de calcio, que consiste en aumentar el calcio intracelular, facilitando finalmente la unión de actina y miosina, y b) independiente de calcio, la cual a través de consecutivas fosforilaciones logra sensibilizar a las proteínas involucradas promoviendo la unión de actina y miosina. Estas acciones son mediadas por agonistas generados principalmente en el endotelio pulmonar, como endotelina-1 y tromboxano, o por agonistas provenientes de otros tipos celulares como la serotonina. Los agentes vasodilatadores regulan la respuesta vasoconstrictora, principalmente inhibiendo la señalización que induce la vasocontricción independiente de calcio, a través de la activación de proteínas quinasas que inhibirán la función de la ROCK quinasa, uno de los últimos efectores de la vasocontricción antes de la formación de la unión de actina y miosina. Esta revisión describe estos mecanismos de primordial importancia en las primeras horas de nuestra vida como individuos independientes.

The extrauterine-milieu adaptation includes a considerable increase in PaO2, that specifically induces structural and vasoactive changes at pulmonary circulation. Such changes transform a poor irrigated circulation into a circulation that receive ∼100% of neonatal cardiac output, supporting the normal alveolar-capillary gas exchange. Local regulation of basal neonatal pulmonary circulation is maintaining by a delicate equilibrium between vasoconstrictor and vasodilator agents. This equilibrium, allows to maintain the pulmonary circulation as an hemodynamic system with a high blood flow and a low vascular resistance. Vasocontrictors action allows actin and light-chain myosin interaction. Two main pathways induced this effect in smooth muscle cell: a) a calcium dependent pathway, that increases intracellular calcium, facilitating actin - myosin binding, and b) the independent calcium pathway, which achieves through consecutive phosphorylation reactions sensitize the proteins involved, promoting the binding of actin and light-chain myosin. These actions are mediated by agonists produced mainly in the pulmonary endothelium, such as endothelin-1 and thromboxane, or by agonists from other cell types such as serotonin. Vasodilator agents regulate the vasoconstrictor response, mainly by inhibiting signals that induce calcium-independent vasoconstriction, through activation of protein kinases, which in turn will inhibit the function of ROCK kinase, one of the last effectors of vasoconstriction before formation of the actin and light-chain myosin binding. This review will focus on describing these mechanisms of primal importance in the first hours of our lives as independent individuals.

Efeitos da pressão positiva nas vias aéreas no antes, durante e depois da cirurgia bariátrica: estudo randomizado e cego / Effects of positive pressure on respiratory tract in bariatric surgery pre-, intra- and postoperative: a randomized and blinded study / Efectos de la presión positiva en las vías aéreas en pre, intra y postoperatorio de la cirugía bariátrica: estudio randomizado y cego

A obesidade é, por si, um fator de risco independente para o surgimento de complicações respiratórias pós-operatórias. O objetivo do estudo foi investigar os efeitos da aplicação de pressão positiva antes, durante e depois do procedimento cirúrgico − em obesos submetidos à cirurgia bariátrica, sobre os volumes e capacidades pulmonares e a mobilidade toracoabdominal. Foram estudados 40 indivíduos com índice de massa corporal entre 40 e 55 kg/m2 e idade entre 25 e 55 anos, submetidos a avaliação pré e pós-operatória e alocados nos grupos: Gpré: tratamento com pressão positiva nas vias aéreas antes da cirurgia; Gpós: pressão positiva nas vias aéreas após a cirurgia; Gintra: pressão positiva nas vias aéreas durante a cirurgia; Gcontrole: fisioterapia convencional conforme rotina hospitalar. Foram avaliadas cirtometria toracoabdominal em três níveis e ventilometria: frequência respiratória, volume corrente, volume minuto e capacidade vital. Os resultados indicaram que, na análise intragrupo, houve aumento significativo da frequência respiratória e queda da capacidade vital para todos os grupos no pós-operatório. O volume corrente apresentou queda significativa somente no Gintra. Não houve diferença significativa nos três níveis de mobilidade toracoabdominal no Gpré. Concluiu-se que a utilização da pressão positiva no pós-operatório de cirurgia bariátrica não promove a manutenção da frequência respiratória e capacidade vital nos seus valores pré-operatórios. Entretanto, quando utilizada no pré-operatório, contribuiu para a manutenção do volume minuto, do volume corrente e da mobilidade toracoabdominal nos três níveis.

Obesity itself is an independent risk factor for the development of postoperative respiratory complications. The objective of the study was to investigate the effects of positive pressure application before, during and after the surgical procedure - in obese patients undergoing bariatric surgery, on lung volumes and capacities and thoracoabdominal mobility. 40 individuals with a Body Mass Index between 40 and 55 kg/m2 and between 25 and 55 years old were studied, submitted to pre- and postoperative evaluation and allocated to the groups: Gpré: treatment with positive airway pressure before surgery, Gpós: positive airway pressure after surgery. Gintra: positive airway pressure during surgery; Gcontrole: conventional physiotherapy according to hospital routine. Thoracoabdominal cirtometry at three levels, and ventilometry: respiratory rate, tidal volume, minute volume and vital capacity were evaluated. The results indicated that in the intragroup analysis there was a significant increase in respiratory rate and drop in vital capacity for all groups in the postoperative period. Tidal volume showed significant decrease only in Gintra. There was no significant difference in the three levels of thoracoabdominal mobility in the Gpré. It was possible to conclude that the use of positive pressure in the postoperative of bariatric surgery does not foster the maintenance of respiratory frequency and vital capacity in its preoperative values. However, when used in the preoperative, contributed to the maintenance of minute volume, tidal volume and thoracoabdominal mobility in the three levels.

La obesidad es, por sí, un factor de riesgo independiente para el surgimiento de complicaciones respiratorias postoperatorias El objetivo del estudio fue investigar los efectos de la aplicación de presión positiva antes, durante y después del procedimiento quirúrgico − en obesos sometidos a la cirugía bariátrica, sobre los volúmenes y capacidades pulmonares y la movilidad toracoabdominal. Fueron estudiados 40 individuos con Índice de Masa Corporal entre 40 y 55 kg/m2 y edad entre 25 y 55 años, sometidos a evaluación pre y postoperatoria y asignados en los grupos: Gpré: tratamiento con presión positiva de la vía aérea antes de la cirugía, Gpós: presión positiva de la vía aérea después de la cirugía. Gintra: Presión positiva de la vía aérea durante la cirugía. Gcontrole: fisioterapia convencional según rutina hospitalaria. Fueron evaluados: cirtometría toracoabdominal en tres niveles, y ventilometría: frecuencia respiratoria, volumen corriente, volumen minuto y capacidad vital. Los resultados indicaron que en el análisis intragrupo hubo aumento significativo de la frecuencia respiratoria y caída de la capacidad vital para todos los grupos en el postoperatorio. No hubo diferencia significativa en los tres niveles de movilidad toracoabdominal en el Gpré. Concluyóse que la utilización de la presión positiva en el postoperatorio de la cirugía bariátrica no promueve la manutención de la frecuencia respiratoria y capacidad vital en sus valores preoperatorios. Todavía cuando utilizada en el preoperatorio, contribuyó al mantenimiento del volumen minuto, del volumen corriente y de la movilidad toracoabdominal en los tres niveles.

Isquemia miocárdica: conceptos básicos, diagnóstico e implicaciones clínicas. Tercera parte / Myocardial ischemia: basic concepts, diagnosis and clinical implications. Part three

Resumen El término «cardiopatía isquémica¼ se refiere a la disfunción del ventrículo izquierdo secundaria a infarto del miocardio, miocardio isquémico viable o enfermedad coronaria severa documentada por arteriografía coronaria, la cual tiene un pobre pronóstico, con una supervivencia del 45% a 5 años. El tratamiento de la cardiopatía isquémica involucra la estimación de la viabilidad en el miocardio afectado para determinar si la revascularización puede generar una remodelación positiva que mejore la función del ventrículo izquierdo. Existen cuatro modalidades básicas usadas en la práctica clínica para calcular la viabilidad miocárdica: tomografía de emisión simple de positrones, tomografía por emisión de positrones, ecocardiograma estrés y resonancia magnética cardiaca. Hoy en día hay estudios que demuestran que la terapia médica mejora la función del ventrículo izquierdo en la cardiopatía isquémica, independiente de la presencia o no de viabilidad o de la revascularización miocárdica; por tanto es posible que otros factores como la cantidad de remodelado, los volúmenes del ventrículo izquierdo, la insuficiencia mitral y la fracción de eyección puedan afectar también los desenlaces. Se requiere definir de manera clara los estadios del remodelado ventricular izquierdo en los cuales la presencia de viabilidad es benéfica y las etapas en las que el remodelado es reversible con la revascularización miocárdica. En cuanto a los métodos para determinar la viabilidad, la resonancia magnética parece dar más respuestas al respecto, ya que puede aportar información adicional relacionada con dimensiones del ventrículo izquierdo, fracción de eyección, fibrosis miocárdica y anormalidades valvulares.

Abstract The term myocardial ischemia refers to a left ventricular dysfunction secondary to a myocardial infarction, viable ischemic myocardium or sever coronary disease documented by means of a coronary angiography, which has a poor prognosis, with five-year survival rate of 45%. Management of myocardial ischemia involves estimating viability of the affected myocardium in order to determine whether revascularization can generate a positive remodelling that improves left ventricle functioning. Four different basic modalities are used in clinical practice to assess myocardial viability: single-photon emission computed tomography, positron emission tomography, stress echocardiogram and cardiac magnetic resonance. Nowadays there are studies that have shown medical therapy improves left ventricle function in ischemic heart disease, regardless of the presence or not of the viability or the myocardial revascularization; therefore, it is possible that other factors such as the amount of remodelling, the left ventricle volumes, mitral insufficiency and ejection fraction could also afffect the outcomes. A clear definition of the left ventricle remodelling states where the presence of viability is beneficial and the stages where the remodelling is reversible with myocardial revascularization is required. With regards to methods for assessing viability, magnetic resonance seems to provide more answers, as it can give additional information related to the dimensions of the left ventricle, ejection fraction, myocardial fibrosis and valvular abnormalities.

Therapeutic effect of prostaglandin E1 in monocrotaline-induced pulmonary arterial hypertension rats / 대한해부학회지

Pulmonary arterial hypertension (PAH) is a severe pulmonary vascular disease characterized by sustained increase in pulmonary arterial pressure and excessive thickening and remodeling of distal small pulmonary arteries. During disease progression, PAH include increase in mean pulmonary arterial pressure, right ventricular (RV) enlargement, increased pulmonary vascular resistance, and smooth muscle hypertrophy in pulmonary arterioles. Several anti-PAH therapies targeting various pathways involved in PAH progression have been approved by the Food and Drug Adminstration. However, many of the currently available anti-PAH drugs suffer from a number of limitations, including short biological half-life, and poor pulmonary selectivity. Prostaglandin E1 (PGE1) is a potent vasodilator with selectivity toward pulmonary circulation when it is administered via the pulmonary route. However, PGE1 has a very short half-life of 5–10 minutes. Therefore, we hypothesized that long-term effect of PGE1 could reduce mal-adaptive structural remodeling of the lung and heart and prevent ventricular arrhythmias in monocrotaline-induced rat model of PAH. Our results revealed that PGE1 reduced ventricular hypertrophy, protein expressions of endothelin-1 and endothelin receptor A, and the expression of fibrosis. These results support the notion that PGE1 can improve the functional properties of RV, highlighting its potential benefits for heart and lung impairment.

Diffuse alveolar hemorrhage in 4 girls / 中国当代儿科杂志

This article reports 4 girls with clinical manifestations of recurrent cough and anemia. The age of onset was less than 4 years, and three of them had shortness of breath. None of them had acute hemoptysis. All the girls had positive results of hemosiderin test for bronchoalveolar lavage fluid. As for imaging examination, 3 patients had ground-glass opacity, and 1 had interstitial change. Three girls were given the treatment for idiopathic pulmonary hemosiderosis and had no response. Selective bronchial arteriography was performed for the 4 girls and found bronchial artery to pulmonary circulation shunt (BPS). After they were diagnosed with BPS, they were given transcatheter embolization. The girls were followed up for half a year after surgery, and none of them was readmitted due to "cough and anemia". BPS manifests as abnormal shunt between the bronchial artery and the pulmonary artery/vein and has unknown causes. It is rare in children and should be considered for children who were thought to have idiopathic pulmonary hemosiderosis and had poor response to corticosteroid therapy.

Cardiopulmonary Exercise Test: Background, Applicability and Interpretation / Teste Cardiopulmonar de Exercício: Fundamentos, Aplicabilidade e Interpretação

ABSTRACT Cardiopulmonary exercise test (CPET) has been gaining importance as a method of functional assessment in Brazil and worldwide. In its most frequent applications, CPET consists in applying a gradually increasing intensity exercise until exhaustion or until the appearance of limiting symptoms and/or signs. The following parameters are measured: ventilation; oxygen consumption (VO2); carbon dioxide production (VCO2); and the other variables of conventional exercise testing. In addition, in specific situations, pulse oximetry and flow-volume loops during and after exertion are measured. The CPET provides joint data analysis that allows complete assessment of the cardiovascular, respiratory, muscular and metabolic systems during exertion, being considered gold standard for cardiorespiratory functional assessment.1-6 The CPET allows defining mechanisms related to low functional capacity that can cause symptoms, such as dyspnea, and correlate them with changes in the cardiovascular, pulmonary and skeletal muscle systems. Furthermore, it can be used to provide the prognostic assessment of patients with heart or lung diseases, and in the preoperative period, in addition to aiding in a more careful exercise prescription to healthy subjects, athletes and patients with heart or lung diseases. Similarly to CPET clinical use, its research also increases, with the publication of several scientific contributions from Brazilian researchers in high-impact journals. Therefore, this study aimed at providing a comprehensive review on the applicability of CPET to different clinical situations, in addition to serving as a practical guide for the interpretation of that test.

RESUMO O teste cardiopulmonar de exercício (TCPE) vem ganhando importância crescente como método de avaliação funcional tanto no Brasil quanto no Mundo. Nas suas aplicações mais frequentes, o teste consiste em submeter o indivíduo a um exercício de intensidade gradativamente crescente até a exaustão ou o surgimento de sintomas e/ou sinais limitantes. Neste exame se mensura a ventilação (VE), o consumo de oxigênio (VO2), a produção de gás carbônico (VCO2) e as demais variáveis de um teste de exercício convencional. Adicionalmente, podem ser verificadas, em situações específicas, a oximetria de pulso e as alças fluxo-volume antes, durante e após o esforço. A análise integrada dos dados permite a completa avaliação dos sistemas cardiovascular, respiratório, muscular e metabólico no esforço, sendo considerado padrão-ouro na avaliação funcional cardiorrespiratória.1-6 O TCPE permite definir mecanismos relacionados à baixa capacidade funcional, os quais podem ser causadores de sintomas como a dispneia, correlacionando-os com alterações dos sistemas cardiovascular, pulmonar e musculoesquelético. Também pode ser de grande aplicabilidade na avaliação prognóstica em cardiopatas, pneumopatas e em pré-operatório, além de auxiliar na prescrição mais criteriosa do exercício em sujeitos normais, em atletas, em cardiopatas e em pneumopatas. Assim como ocorre com o uso clínico, a pesquisa nesse campo também cresce e várias contribuições científicas de pesquisadores nacionais são publicadas em periódicos de alto fator de impacto. Sendo assim, o objetivo deste documento é fornecer uma revisão ampla da aplicabilidade do TCPE nas diferentes situações clínicas, bem como servir como guia prático na interpretação desse teste propedêutico.

Isquemia miocárdica: conceptos básicos, diagnóstico e implicaciones clínicas. Primera parte / Myocardial ischaemia: basic concepts, diagnosis and clinical implications

Resumen La isquemia miocárdica es el conjunto de una serie de fenómenos fisiológicos que se manifiesta por condiciones clínicas como isquemia silente, angina estable y síndromes corona-rios agudos. Diversos mecanismos de la regulación del flujo sanguíneo, la demanda miocárdica, la liberación de adenosina y la función del endotelio en las arterias coronarias son claves para mantener la irrigación miocárdica y han sido la base fisiológica para el desarrollo de pruebas de detección de isquemia como lo es el flujo de reserva fraccional, que hoy día hace parte de las recomendaciones de las guías.

Abstract Myocardial ischaemia as a whole is a series of physiological phenomena manifested by clinical conditions such as silent ischaemia, stable angina and acute coronary syndromes. Various blood flow regulation mechanisms, myocardial demand, adenosine release and endot-helial function in the coronary arteries are vital for maintaining myocardial irrigation, and have been the physiological basis for tests like fractional flow reserve, developed to detect ischaemia, that today forms part of the guideline recommendations.

Evaluation of pulmonary artery pressure and resistance by pulsed Doppler echocardiography in patients with end-stage renal disease on dialysis therapy

Background: Pulmonary hypertension [PH] is one of the most important comorbidities in patients undergoing hemodialysis [HD]. The goal of the present work is to determine the possible etiologic factors for its occurrence

Methods: The prevalence of PH was estimated by Doppler echocardiography in a cohort of 100 patients aged 49.3 +/- 13.9 years on regular HD. Mean pulmonary artery pressure was estimated from pulmonary acceleration time by Mahan's regression equation. Pulmonary vascular resistance and pulmonary capillary wedge pressure were calculated. We focused on the effect of HD on left and right ventricle diastolic and systolic function. Right ventricle systolic function was assessed by tricuspid annular systolic excursion and pulsed Doppler myocardial performance index. Since impaired endothelial function was postulated as an underlying cause of PH, we studied the effects of HD on brachial artery endothelial function

Results: The current study found that pulmonary hypertension was prevalent in 70% of patients on dialysis. Left atrium diameter, left ventricle mass indexed to body surface area, and mitral E/E0 were increased in the dialysis group [4.4 +/- 0.2 cm, 126.5 +/- 24.6 g/m[2], and 16.9 +/- 4.4, respectively, p < 0.001 for all]. Pulmonary artery systolic pressure was positively correlated to duration of dialysis and negatively correlated to glomerular filtration rate [p < 0.001 and r = -0.991]. Pulmonary vascular resistance was significantly increased in dialysis patients [1.9 +/- 0.2 Wood units vs. 1.2 Wood units in controls, p < 0.001]. Endothelial dysfunction, defined as brachial artery flow mediated dilatation <6%, was found in 46% of dialysis group

Conclusion: Increased pulmonary artery systolic pressure in the HD population could be attributed to left atrium dilatation and left ventricle diastolic dysfunction. Pulmonary vascular resistance was significantly increased in dialysis group. This might be explained by impaired endothelial nitric oxide synthesis that not only caused systemic vasoconstriction but also affected the pulmonary vasculature

Use of Extracorporeal Membrane Oxygenation in a Fulminant Course of Amniotic Fluid Embolism Syndrome Immediately after Cesarean Delivery / 대한구급학회지

Amniotic fluid embolism is rare but is one of the most catastrophic complications in the peripartum period. This syndrome is caused by a maternal anaphylactic reaction to the introduction of fetal material into the pulmonary circulation. When amniotic fluid embolism is suspected, the immediate application of extracorporeal mechanical circulatory support such as veno-arterial extracorporeal membrane oxygenation (ECMO) or cardiopulmonary bypass should be considered. Without the application of extracorporeal mechanical circulatory support, medical supportive care might not be sufficient to maintain cardiopulmonary stabilization in severe cases of amniotic fluid embolism. In this report, we present the case of a 36-year-old pregnant woman who developed an amniotic fluid embolism immediately after a cesarean section. Her catastrophic event started with the sudden onset of severe hypoxia, followed by circulatory collapse within 8 minutes. The veno-arterial mode of extracorporeal membrane oxygenation was initiated immediately. She was successfully resuscitated but with impaired cognitive function. Thus, urgent ECMO should be considered when amniotic fluid embolism syndrome is suspected in patients presenting acute cardiopulmonary collapse.

Suspected Pulmonary Embolism during Hickman Catheterization in a Child: What Else Should Be Considered besides Pulmonary Embolism? / 대한구급학회지

A 16-month-old girl with acute lymphoblastic leukemia expired during Hickman catheter insertion. She had undergone chemoport insertion of the left subclavian vein six months earlier and received five cycles of chemotherapy. Due to malfunction of the chemoport and the consideration of hematopoietic stem cell transplantation, insertion of a Hickmann catheter on the right side and removal of the malfunctioning chemoport were planned under general anesthesia. The surgery was uneventful during catheter insertion, but the patient experienced the sudden onset of pulseless electrical activity just after saline was flushed through the newly inserted catheter. Cardiopulmonary resuscitation was commenced aggressively, but the patient was refractory. Migration of a thrombus generated by the previous central catheter to the pulmonary circulation was suspected, resulting in a pulmonary embolism.

Lyophilized allografts without pre-treatment with glutaraldehyde are more suitable than cryopreserved allografts for pulmonary artery reconstruction

Various methods are available for preservation of vascular grafts for pulmonary artery (PA) replacement. Lyophilization and cryopreservation reduce antigenicity and prevent thrombosis and calcification in vascular grafts, so both methods can be used to obtain vascular bioprostheses. We evaluated the hemodynamic, gasometric, imaging, and macroscopic and microscopic findings produced by PA reconstruction with lyophilized (LyoPA) grafts and cryopreserved (CryoPA) grafts in dogs. Eighteen healthy crossbred adult dogs of both sexes weighing between 18 and 20 kg were used and divided into three groups of six: group I, PA section and reanastomosis; group II, PA resection and reconstruction with LyoPA allograft; group III, PA resection and reconstruction with CryoPA allograft. Dogs were evaluated 4 weeks after surgery, and the status of the graft and vascular anastomosis were examined macroscopically and microscopically. No clinical, radiologic, or blood-gas abnormalities were observed during the study. The mean pulmonary artery pressure (MPAP) in group III increased significantly at the end of the study compared with baseline (P=0.02) and final [P=0.007, two-way repeat-measures analysis of variance (RM ANOVA)] values. Pulmonary vascular resistance of groups II and III increased immediately after reperfusion and also at the end of the study compared to baseline. The increase shown by group III vs group I was significant only if compared with after surgery and study end (P=0.016 and P=0.005, respectively, two-way RM ANOVA). Microscopically, permeability was reduced by ≤75% in group III. In conclusion, substitution of PAs with LyoPA grafts is technically feasible and clinically promising.

Suspected Pulmonary Embolism during Hickman Catheterization in a Child: What Else Should Be Considered besides Pulmonary Embolism? / 대한중환자의학회지

A 16-month-old girl with acute lymphoblastic leukemia expired during Hickman catheter insertion. She had undergone chemoport insertion of the left subclavian vein six months earlier and received five cycles of chemotherapy. Due to malfunction of the chemoport and the consideration of hematopoietic stem cell transplantation, insertion of a Hickmann catheter on the right side and removal of the malfunctioning chemoport were planned under general anesthesia. The surgery was uneventful during catheter insertion, but the patient experienced the sudden onset of pulseless electrical activity just after saline was flushed through the newly inserted catheter. Cardiopulmonary resuscitation was commenced aggressively, but the patient was refractory. Migration of a thrombus generated by the previous central catheter to the pulmonary circulation was suspected, resulting in a pulmonary embolism.