Figure 1.

Measurement of coronary flow reserve (CFVR) by transthoracic Doppler echocardiography (TTDE) was proven to be a reliable tool with which to investigate coronary microvascular function in many cardiac and systemic diseases. Although initially developed to assess the hemodynamic relevance of an epicardial coronary stenosis, the study of CFVR by TTDE during the last 30 years expanded to a variety of different medical conditions, from organ transplantation to metabolic and inflammatory disorders and from cardiomyopathies to pediatric diseases.