lfredo M Germain A

Disfunción endotelial como alteración primaria en las patologías vasculares

Endothelium controls vascular smooth muscle tone by secreting relaxing and contracting factors. There is a constant release of endothelium derived relaxing factors, mainly nitric oxide, a potent vasodilator, inhibitor of platelet aggregation, monocyte adhesion and smooth muscle proliferation. In addition, the endothelium may increase the release of NO in response to humoral stimulation by vasoactive substances such as acetylcholine, bradikinin or substance P. Although the endothelium releases a number of products, no single blood test has yet proved useful to determine normal endothelial function or as early abnormalities. The most useful test of endothelial function relies on the meassurement of endothelium-dependent dilatation in response to pharmacological or physiologic stimuli. The alteration of this response is known as endothelial dysfunction and has been observed in a variety of circumstances related to cardiovascular risk. This review summarizes the evidence that sustains this association and emphasizes the clinical utility of assessing endothelial function presenting two clinical cases of hypercholesterolemia in which a high-resolution vascular ultrasound in the braquial artery was used. (Rev Med Chile 2000; 128: 659-70).

Hipertensión pulmonar y embarazo

A 36 year old woman, with an 18 year history of syncope, became pregnant shortly after a cardiac catheterization demonstrated a high pulmonary arterial pressure and resistance and a low cardiac output. During pregnancy she remained stable at NYHA FC III, on nifedipine, apresoline, isosorbide, aspirin and bed rest. At 28 weeks, catheterization showed a decreased pulmonary pressure and an increased cardiac output. At 38 weeks, she was submitted to an elective caesarean section, and delivered a healthy newborn of 2820 g. After 5 months, her catheterization showed a pulmonary artery pressure similar to the pre-pregnancy study. Her condition deteriorated, leading to death 10 months later. Urinary 6-keto-PGF1∂, nitrates/nitrites, kallikrein and angiotensin-(1-7) were increased from 13 to 33 weeks, to drop in week 35 of pregnancy. The safe maternal and fetal outcome, and the intragestational hemodynamic improvement are attributed to a close multidisciplinary surveillance, and to the effects of the endogenous vasodilators of pregnancy on the reversible component of the pulmonary hypertension. Reports in the literature show a decrease in maternal mortality rate, from 56% for the period previous to 1963, to 34 and 30% for those spanning between 1978-1996 y 1997-2001 respectively (Rev Med Chile 2002; 130: 201-8)

Evaluación ultrasonográfica de la función endotelial en niños y adultos chilenos

: Flow mediated dilation of thebrachial artery was measured by high resolution ultrasonography in healthy children (n=32)and adults (n=69) of both gender, in a group of 8 healthy women during 4 periods of pregnan-cy and late postpartum, and in 22 men and women with a history of stroke or coronary heartdisease.

Hiperaldosteronismo primario y embarazo: Lecciones obtenidas de 2 casos clínicos

Based on two patients, we discuss the difficulties in diagnosing and managing primary aldosteronism in pregnancy, which derive from changes of the renin-angiotensin-aldosterone axis, from the uncertainty regarding blood pressure control along gestation and postpartum, and from the contraindication to the use of spironolactone. The first case is a 27 years old woman with a long standing refractory hypertension, a hemorrhagic stroke with left brachial hemiplegia and crural hemiparesia, two miscarriages, one stillbirth and one offspring with intrauterine growth retardation. Due to hypokalemia, a plasma aldosterone/renin activity ratio of 91, and a negative genetic screening for glucocorticoid remediable aldosteronism (GRA), a primary hyperaldosteronism with normal adrenals in CT scan was diagnosed, and good blood pressure control was attained with spironolactone. After two and a half years of normotension, a fifth pregnancy, managed with methyldopa evolved with satisfactory blood pressures, plasma potassium, fetal growth, uterine and umbilical arterial resistance indexes, and maternal endothelial function. At 37 1/2 weeks of pregnancy the patient delivered a healthy newborn weighing 2,960 g. Blood pressure rose during the 48 hours of postpartum in the absence of proteinuria and required iv hydralazine. The second patient is a 37 years old woman, with known refractory hypertension for 7 years, hypokalemia, plasma aldosterone/renin activity ratio greater than 40, normal adrenals in the CAT scan, and a negative genetic screening for GRA. She had normotensive pregnancies 5 and 3 years prior to the detection of hypertension, with hypertensive crisis in both postpartum periods, retrospectively considered as expressions of primary hyperaldosteronism (Rev Med Chile 2002; 130: 1399-1405)

Consenso salud materna para Chile en el nuevo milenio

Contexto: Chile presenta una tendencia secular hacia una sostenida mejoria en los principales indicadores materno-infantiles. Su situacion constituye una experiencia positiva a nivel de la region de Latino-America y el Caribe. Sin embargo, esta tendencia se ha estancado en los ultimos diez anos lo que produce una situacion inestable y preocupante desde el punto de vista de la salud publica materna. Esto motiva una reunion de expertos a nivel nacional e internacional para proponer estrategias para el alto nivel politico orientadas a alcanzar los Objetivos 4 y 5 del Milenio. Conclusion: Este documento de consenso sobre mortalidad materna, sugiere un enfrentamiento en dos ejes: primero, enfrentar la nueva realidad epidemiologica desde la etapa pre-concepcional, esto incluye considerar la alta prevalencia de obesidad, hipertension arterial, diabetes, hiperlipidemias e hipotiroidismo en la poblacion, y por otro lado reforzar la seguridad de la asistencia del embarazo, parto y puerperio en los lugares mas alejados y mas vulnerables del pais. Es necesario focalizar las intervenciones en los grupos de mayor riesgo vital (edades extremas de la vida fertil y portadoras de enfermedades medico-quirurgicas severas, que se reflejan en el aumento proporcional de las causas indirectas de muerte materna), reforzar las actividades de auditorias de mortalidad/near miss, asi como controlar el aumento alarmante de la tasa de partos por cesareas.

PARTO PREMATURO ASOCIADO A COLESTASIA INTRAHEPATICA DEL EMBARAZO: ROL DEL ACIDOCOLICO EN LA MODULACION DE LA VIA OCITOCINA-RECEPTOR DE OT EN EL MIOMETRIO

Se ha reportado una asociacion entre CIE y distres fetal, muerte fetal in utero y sintomas de parto prematuro/parto prematuro. Con la hipotesis que en la CIE el aumento en los acidos biliares, en particular acido colico, activa la via ocitocina-receptor de ocitocina (OT-ROT) en el miometrio, generando un inicio prematuro del trabajo de parto, evaluamos la sensibilidad miometrial a OT in vitro e in vivo, y la expresion de mRNA en pacientes CIE y controles y la capacidad de acido colico para regular la activacion de la via OT-ROT. Las pacientes con CIE mostraron una alta sensibilidad a OT in vivo e in vitro comparado con controles. Al incubar segmentos/celulas en cultivo de miometrio con acido se observo una marcado aumento de la sensibilidad contractil para la OT y un aumento de la expresion celular del mRNA y los niveles de la proteina del ROT. La activacion de la via OT-ROT parece ser el resultado de un aumento de la sintesis/funcion de RsOT mediada por el acido colico. Esto resultados entregan las bases celulares/moleculares que podrian explicar la asociacion entre CIE y parto prematuro