ABSTRACT
Embora a avaliação da viabilidade miocárdica seja comum na prática do cardiologista, muitos médicos têm dúvidas a respeito dos resultados dos métodos diagnósticos. A medicina nuclear tem papel importante nos estudos de viabilidade, mas os laudos precisam ser interpretados num contexto clínico e fisiopatológico. Este artigo teve o objetivo de revisar a origem e a evolução do conceito da viabilidade miocárdica. São expostos os métodos diagnósticos com ênfase na medicina nuclear com uma explicação funcional sobre cada tipo de exame. A partir disso, são mostradas imagens como exemplos e é proposta uma maneira de atuar nesses casos baseada na clínica, na porcentagem de miocárdio acometido e na topografia das lesões coronarianas (proximais ou distais). (AU)
Although assessing myocardial viability is a common cardiology practice, many physicians question the results of diagnostic methods. Nuclear medicine plays an important role in viability studies, but the reports require interpretation in a clinical and pathophysiological context. this article was aimed at reviewing the origin and evolution of myocardial viability. Here we present diagnostic methods by emphasizing nuclear medicine and provide a functional explanation of each test type using example images. We also propose how to act in these cases based on clinic examination findings, the percentage of affected myocardium, and coronary lesion topography (proximal or distal).(AU)
Subject(s)
Humans , Echocardiography/methods , Myocardial Stunning/diagnosis , Myocardial Stunning/physiopathology , Ventricular Dysfunction, Left/therapy , Nuclear Medicine/instrumentation , Rubidium/administration & dosage , Thallium/administration & dosage , Tomography, Emission-Computed, Single-Photon/methods , Clinical Diagnosis , Echocardiography, Stress/methods , Positron-Emission Tomography/methods , Dobutamine/administration & dosage , Myocardial Revascularization/methodsABSTRACT
Although thallium-201 exercise scintigraphy has been established for the detection of myocardial ischemia and viability, little is known regarding the myocardial thallium-201 kinetics during angioplasty. Herein, we report a 77-year old man with angina pectoris, in whom serial myocardial imaging after a single dose of thallium-201 was helpful in identifying not only the culprit lesion and myocardial viability, but also the dynamic changes in myocardial perfusion during angioplasty. Thallium-201 images after exercise showed a perfusion defect in the inferior wall, with a trivial redistribution 3 hours after the exercise and a marked improvement 24 hours later. Coronary angiography, performed 27 hours after exercise scintigraphy, showed severe stenosis in the right coronary artery. Guidewire crossing of the lesion interrupted the antegrade flow, which was restored after balloon dilation and stent implantation. Thallium-201 images, 2 hours after angioplasty [i.e., 30 hours after exercise], showed a decreased tracer uptake in the inferior wall, which improved the next day [i.e., 48 hours after exercise]. Cardiac biomarkers were negative in the clinical course
Subject(s)
Humans , Male , Myocardial Ischemia/diagnosis , Thallium/administration & dosage , Heart Diseases/diagnostic imaging , Thallium RadioisotopesABSTRACT
Diversas condiciones clínicas impiden efectuar ejercicio isotónico en correa sin fin o bicicleta ergométrica en casos en los que la evolución no invasiva de la insuficiencia coronaria es importante con fines diagnósticos o pronósticos o para evaluar los resultados de tratamientos médicos o quirúrgicos. El dipiridamol, droga que tiene potente acción vasodilatadora mediada por un aumento del nivel circulante dde adenosina, asociado a marcadores radioactivos de perfusión coronaria (Talio-201; isonitrilo Tc-99m) ha demostrado ser una alternativa muy útil y segura cuyo rendimiento es comparable con la técnica Talio-ejercicio. El dipiridamol produce vasodilatación y aumenta 3 a 5 veces el flujo coronario por espacio de 30 a 60 minutos, lo que permite evidenciar áreas miocárdicas hipoperfundidas. La seguridad de la prueba dipiridamol-Talio es muy grande. No obstante suele desencadenar angina y alteraciones isquémicas del electrocardiograma, los que se antagonizan rápida y totalmente con aminofilina