Función endotelial: evaluación ultrasonográfica e implicancias fisiopatológicas / Endothelial function: ultrasonographic evaluation and physiopathological implications

Durante las últimas décadas se ha establecidoel rol del endotelio sobre el control del tono vascular, coagulación, fibrinolisis y crecimiento celular estudios experimentales han demostrado que la integridad funcional del endotelio ejerce efectos antiaterogénicos y antitrombóticos. La alteración de este equilibrio es considerada como un evento precoz y determinante en el desarrollo de aterogénesis y de riesgo cardiovascular. El síndrome de disfución endotelial es propuesto como un predictor independiente de progresión de la enfermedad coronoaria y de eventos cardiovasculares. Su evaluación puede ser realizada por diversos métodos invasivos como la administración intra-arterial de vasodilatadores. Sin embargo, la naturaleza de dichos estudios limita su utilización seriada y aplicación clínica. La medición no invasiva de la dilatación mediada por flujo a través de ultrasonografía de alta resolución en arteria braquial es una técnica que ha emergido como una herramienta de utilidad en el diagnóstico y valoración de riesgo cardiovascular. En esta revisión se abordarán las implicancias fisiopatológicas del síndrome de disfunción endotelial y su determinación con ultrasonografía de alta resolución en arteria braquial. Se describirán los aspectos técnicos, aplicaciones clínicas, ventajas y limitaciones en la identificación de pacientes en riesgo cardiovascular, incluidos grupos aún poco conocidos, como mujeres con falla reproductiva de origen isquémico y en la postmenopausia.

Recomendaciones para el manejo de las crisis hipertensivas: documento de consenso de la Sociedad Chilena de Hipertensión Arterial / Recommendations for the management of hypertensive crisis: a consensus document of the chilean society of hypertension

The management of severe hypertension in the emergency setting demands a careful evaluation of the different underlying clinical situations, and of the impending risk for the life of the patient or of acute organ damage. Hypertensive emergencies and urgencies have to be identified, and distinguished from chronic severe hypertension, a frequent presentation to the emergency services. A thorough clinical evaluation, and not the magnitude of the blood pressure elevation, should be the basis of the differential diagnosis; this will guide the setting required for treatment (intensive care unit, ward or ambulatory), the drugs of choice, as well as the velocity of blood pressure reduction. Special emphasis has to be given to the management of cerebrovascular accidents and severe preeclampsia, as the reduction of blood pressure entails a risk of hypoperfusion of critical territories as the brain and fetus respectively. A wide range of drugs permits a tailored treatment of a variety of clinical situations. Efforts have to be made to detect and manage chronic hypertensive patients in order to reduce the consultation load represented by severe hypertensives in emergency services, by preventing hypertensive crisis, in order to focalize on real situations of risk

Hipertensión pulmonar y embarazo / Pulmonary hypertension and pregnancy

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 percent for the period previous to 1963, to 34 and 30 percent for those spanning between 1978-1996 y 1997-2001 respectively

Hipertensión arterial refractaria y uso de drogas anticonvulsivantes: caso clínico / Resistant hypertension and anticonvulsant drugs: report of 1 case

Resistant arterial hypertension is uncommon when there is good compliance to antihypertensive therapy and secondary causes have been ruled out. We report a 41 years old male that suffered hypertensive encephalopathy and received prophylactic anticonvulsant therapy showing progressive raise of arterial pressure levels. Renovascular hypertension, aldosteronism and pheochromocytoma were discarded and, in spite of combined use of antihypertensive drugs, he did not achieve normal blood pressure. When phenytoin was discontinued, blood pressure temporarily normalized. Carbamazepine was started and blood pressure raised again. lt fell when this medication was discontinued. Antiepileptic agents could induce drug metabolizing system and thus reduce the effects of antihypertensive medications

¿Puede prevenirse la preeclampsia a través del reconocimiento de la disfunción endotelial primaria y de su manejo con L-Arginina?: ¿cómo ayuda el ultrasonido Doppler? / Can we prevent preeclampsia through the recognition of primary endothelial dysfunction and its handling with L-Arginina?: how does the Doppler ultrasound help?

Con la hipótesis de que la disfunción endotelial primaria representa un factor de riesgo manejable para patologías asociadas a defectos de placentación, como el aborto recurrente y la preeclampsia, se estudiaron 13 mujeres con abortos recurrentes, 16 mujeres con antecedentes de preeclampsia severa precoz, y se compararon con 12 mujeres que cursaron embarazos normales. El 39 por ciento de las mujeres con abortos recurrentes y el 44 por ciento de las mujeres con preeclampsia previa presentó disfunción endotelial severa, comparado con el 0 por ciento en mujeres controles (Chi2). La suplementación oral de L-Arginina (0.1 g/kg/día), por 2 semanas a 10 mujeres que mantuvieron resistencia de arterias uterinas elevada en gestaciones tempranas en dos evaluaciones utrasonográficas se asoció a una normalización en el índice de resistencia (0,89 ñ 0,02 a 0,79 ñ 0,03, p < 0,05), mientras que las mujeres que recibieron placebo mantuvieron un índice de resistencia elevado (0,93 ñ 0,01 a 0,86 ñ 0,02, n.s.). El suplemento de L-Arginina administrado a partir de la décima semana de gestación a 12 mujeres con desórdenes previos relacionados con la placentación se asoció a un buen resultados reproductivo. Estos apoyan la hipótesis que la disfución endotelial severa es una condición de base prevalente en pacientes que presentan preeclampsia severa previa o abortos recurrentes. Además, sugiere que en estas pacientes un aumento en la vía L-Arginina-NO a través del suplemento de L-Arginina en gestaciones precoces, podría mejorar la función endotelial, la resistencia vascular de arterias uterinas y el resultado perinatal

Disfunción endotelial como alteración primaria en las patologías vasculares / Endothelial dysfunction as a primary alteration in vascular diseases

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

Recomendaciones sobre el uso de la monitorización ambulatoria de presión arterial: documento de consenso de la Sociedad Chilena de Hipertensión / Recommendations for the use of continuous ambulatory blood pressure monitoring: consensus document of the chilean hypertension society

Continuous ambulatory blood pressure monitoring is a diagnostic technique devised as a consequence of the great variations in blood pressure measurements. It allows multiple daily measurements, nocturnal monitoring, avoids the stress of blood pressure measurements, gives a picture of pressure behavior during 24 hours and reduces observer related errors. The equipment used must be accurate and validated using international protocols. Accepted indications for continuous ambulatory blood pressure monitoring are white coat hypertension, episodic hypertension, resistance to medications and assessment of symptoms or autonomic dysfunction. Other indications with less clear cut usefulness, are high risk cardiac, renal or pregnant patients and an accurate blood pressure control. We describe equipment calibration, elements that must be considered in the reports, result interpretation and conclusions. Normal blood pressure ranges for children and pregnant women are also reported

Medición de la actividad de renina plasmática a niveles bajos: optimización del método / Measurement of low levels of plasma renin activity: a methodological improvement

Background: The present method to measure plasma renin activity is cumbersome and imprecise, factors that limit its clinical application. Aim: To assess the importance of blood sampling conditions and the usefulness of increasing incubation time to measure plasma renin activity at low levels. Patients and methods: Twenty hypertensive patients, 14 female, aged 14 to 76 years old, were studied. Two blood samples were obtained after a 10 min rest in the sitting position and after a 30 min rest in supine position. One blood sample, of each condition was sent lo the laboratory at room temperature and the other sample was sent refrigerated. Angiotensin I concentration was determined after 3 h of enzymatic incubation at 37°C and, in subjects with an activity of less than 1 ng/ml/h, after 18 h of incubation. Results: No significant differences in plasma renin activity were observed between the samples obtained with different rest times or different transportation methods. In people with low plasma renin activity, the 18 h enzymatic incubation reduced the lower detection from 0.3 to 0.014 ng/ml/h and the coefficient of variation from 14.4 to 3.2 percent. Conclusions: A simplified blood sampling method does not change plasma renin activity values, and tbe longer enzymatic incubation in people with low plasma renin activity improves both the sensitivitv and accuracy of the determination