El impacto de la detección de disfunción endotelial en la aterosclerosis: estudio mediante tomografía por emisión de positrones / Impact of the detection of endothelial dysfunction in atherosclerosis: Assessment by positron emission tomography

El endotelio juega un papel importante en la regulación del líquido intracelular, la permeabilidad vascular, en la modulación del tono vascular focal y la angiogénesis. La disfunción endotelial se manifiesta por la pérdida de la capacidad del endotelio de modular el comportamiento fisiológico del lecho vascular y actualmente se considera un marcador pronóstico de la enfermedad arterial coronaria. La relevancia de estudiar la disfunción endotelial radica en que ésta se ha observado en diversas patologías como diabetes mellitas (DM), dislipidemia, hipertensión arterial sistémica, tabaquismo o en enfermedades inmunológicas como síndrome antifosfolípido y lupus eritematoso sistémico. La Tomografía por Emisión de Positrones (PET) es un método no invasivo que permite cuantificar en términos absolutos el flujo miocárdico en reposo, esfuerzo y durante la estimulación adrenérgica, siendo considerado en la actualidad el estándar de oro para valorar la función endotelial. Por lo tanto el PET es una herramienta diagnóstica muy útil en identificar a los pacientes con disfunción endotelial y en evaluar la respuesta a la terapia administrada en enfermedades que se acompañen de ésta. Permitiendo un control óptimo y prevención de eventos adversos de estas enfermedades.

The endothelium plays an important role in the regulation of the intracellular fluid, vascular permeability, and modulation of vascular focal tone and angiogenesis. Endothelial dysfunction is manifested by the loss of the endothelium ability to modulate physiology changes in its vascular bed, and actually it is considered a prognostic marker of coronary artery disease. The relevance of assessing endothelial dysfunction relies in that it has been observed in different pathologies like DM, dyslipidemia, hypertension, tabaquism and in immunologic diseases like antiphospholipid syndrome and systemic lupus. PET is a non invasive method that allows the absolute quantification of myocardial blood flow during rest, stress and adrenergic stimulation, which allows to asses endothelial function. Therefore PET is a useful diagnostic technique to identify patients with endothelial dysfunction, and in the assessment of its response to administered therapy, allowing an optimal control and prevention of secondary adverse events of these diseases.

Efecto del tratamiento combinado con metformina/glimepirida sobre la función endotelial en pacientes con diabetes mellitus tipo 2 evaluados mediante PET / Effects of the combined treatment with Metformin/Glimepiride on endothelial function of patients with type 2 diabetes mellitus: a positron emission tomography (PET) evaluation study

The purpose of this study was to determine the effect of treatment, with Metformin alone or with the combination of Glimepiride/Metformin, on coronary endothelial function in asymptomatic patients with recently diagnosed type 2 diabetes mellitus (DM) Methods: 16 asymptomatic patients with type DM2 and 15 healthy controls (HC) were studied. At baseline and after treatment, myocardial blood flow (MBF) was measured with 13N-ammonia Possitron Emission Tomography (PET) at rest, during cold pressor testing (CPT) and during pharmacologic stress with adenosine. The endothelial dependent vasodilation index (EDVI), myocardial flow reserve (MFR) and the percentage of the change between rest MBF and CPT MBF (%deltaMBF) were calculated as markers of endothelial function. MBF was normalized to the rate pressure product (RPP). RESULTS: EDVI and %deltaMBF were significantly lower in diabetic patients before treatment in comparison with HC demonstrating endothelial dysfunction in the former. Treatment with Glimepiride/Metformin significantly increased EDVI and %deltaMBF in diabetic patients from baseline, thus showing an improvement in coronary endothelial function.

Importancia de la detección de viabilidad miocárdica: evaluación con tomografía por emisión de positrones con 18F-FDG / Value of the assessment of myocardial viability: evaluation with positron emission tomography 18F-FDG

It used to be thought that the consequences of coronary artery disease were final, and that the prognosis of the patient was limited to the extent of the ventricular dysfunction. This paradigm changed radically when the concept of hibernating myocardium was introduced, which states the existence of tissue that can regain contractile function after being re-vascularized. This introduced a new concept in cardiology: myocardial viability. This work presents a clear example of the importance of detecting myocardial viability in selected patients, due to the impact not only in treatment but in prognosis as well. It is also emphasized that positron emission tomography (PET) is the gold standard method to detect myocardial viability.