Gloria Valdés S

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)

Recomendaciones sobre el uso de la monitorización ambulatoria de presión arterial.: Documento de consenso de la Sociedad Chilena de Hipertensión

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.

Actualización de las recomendaciones sobre el uso de la monitorización ambulatoria de presión arterial. Documento de consenso de la Sociedad Chilena de Hipertensión

Ambulatory blood pressure monitoring (ABPM) is a valuable toolto evaluate the blood pressure pattern, to identify hypertensive patients, to diagnose white coatand masked hypertension and in situations in which a tight control of hypertension is crucial.This is an update of 1999 consensus recommendations about the use to ABPM, considering thatthere is new evidence concerning its benefits, and the clinical experience with its applicationhas increased. Equipment programming, its installation, the interpretation and analysis of thedata are described, and a report sheet for patients is included. New recommendations havebeen added to the accepted indications. Normal blood pressure ranges for children andpregnant women have been replaced by new data (Rev Med Chile 2009; 137: 1235-47).(

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.

Hipotensión ortostática: una manifestación sugerente de feocromocitoma

Pheochromocytoma, though an uncommon cause of hipertension, can be a lethal condition. Because of this it is mandatory to diagnose it or rule it out in presence of suggestive symptoms. Typical symptoms are palpitations, sweating, severe headaches and hypertension. However, there are other suggestive symptoms of this dangerous endocrine entity, one of which is the orthostatic hypotension. We report the case of a 65 years old female patient with long standing hypertension in whom the pheochromocytoma was suspected after episodes of orthostatic hypotension. Although this manifestation was described almost fifty years ago, its frequency and pathophysiology has not yet been well established and fully elucidated. Moreover, it has meaningful implications in relation to preoperatory management and the timing of surgery (Rev Med Chile 2003; 131: 1429-33)

Recomendaciones para el manejo de las crisis hipertensivas: Documento de Consenso de la Sociedad Chilena de Hipertensión Arterial

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 (Rev Med Chile 2002; 130: 322-31)

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)

Hipertensión arterial refractaria y uso de drogas anticonvulsivantes: Caso clínico

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. (Rev Med Chile 2001; 129: 1325-7)

Análisis de las publicaciones biomédicas chilenas indizadas en PubMed, en los años 2008 y 2009

Background: During the years 2008 and 2009, 1191 biomedical articles authored by Chilean investigators working in Chile were indexed in PubMed. Aims: To evaluate the potential visibility of those articles, according to scientometric indexes of the journals where they were published. Methods: Those journals where the articles had been published were identified and each journal’s Impact Factor (JIF), 5-year JIF, SCImago Journal Rank (SJR), SCImago Quartiles (Q) for 2010 and the Source Normalized Impact per Paper (SNIP) for 2008-2009 were identified. Results: Three hundred and twelve articles (26,2%) were dedicated to experimental studies in animals, tissues or cells and they were classified as “Biomedicine”, while 879 (73,8%) were classified as “Clinical Medicine”; in both areas the main type of articles were original reports (90% and 73.6%, respectively). Revista Medica de Chile and Revista Chilena de Infectologia concentrated the greater number of publications. Articles classified in Biomedicine were published more frequently in English and in journals with higher scientometric indexes than those classified in Clinical Medicine. Conclusions: Biomedical articles dealing with clinical topics, particularly case reports, were published mostly in national journals or in foreign journals with low scientometric indexes. It can be partly attributable to the authors’ interest focused in reaching local readers. The evaluation of research productivity should combine several scientometric indexes, selected according to the field of research, the institutional and investigators’ interests, with a qualitative and multifactorial appreciation.