SPONTANEOUS INTRACARDIAC CONTRAST AND EMB OLIC RISK

Spontaneous contrast in the form of smokey echos in the cardiac chambe rs is considered to be a risk factor for thromboembolism. The aggregat ion of red blood cells results in larger target which diffuse a measur able in vitro ultrasonic signal. The phenomenon of erythrocytic aggreg ation is dependent on the red cells themselves, the plasma fibrinogen and conditions of blood flow. The other constituents of the blood only reflect a small amount of ultrasound, usually undetectable. Transoeso phageal echocardiography with high frequency transducers (5 MHz) posit ioned in close proximity to the cardiac chambers, has become the refer ence method for detecting spontaneous contrast. This phenomenon is alm ost exclusively observed in the left atrium and left auricle and rarel y in the other cardiac chambers or descending aorta. In pathological s ituations, spontaneous contrast is essentially implicated in two condi tions: mitral valve obstacles and non-valvular atrial fibrillation. Co nversely, moderate to severe mitral regurgitation is a negative predic tive factor of spontaneous contrast. However, a purely qualitative app reciation of spontaneous contrast which may be influenced by the gain setting and technical specifications of the echocardiograph, and the s ubjectivity of the operator, is an important limitation. Therefore, th e identification of quantitative markers of spontaneous contrats and n ew therapeutic antithrombotic protocols remain essential.