OPTIMIZED TRANSCRANIAL DOPPLER TECHNIQUE FOR THE DIAGNOSIS OF CARDIACRIGHT-TO-LEFT SHUNTS

Transcranial Doppler sonography (TCD) is a simple method to detect a r ight-to-left cardiac shunt, although standardized procedures do not ex ist. in this study 69 patients were tested according to predetermined criteria and procedures (cluster of >10 microbubbles, duration between injection in the cubital vein and detection in the middle cerebral ar tery [MCA] less than or equal to 10 sec). Agitated saline solution was compared to oxypolygelatine, a plasma volume expander, as contrast me dia. Valsalva's maneuver and coughing were used to provoke right-to-le ft cardiac shunting, detected by TCD, transthoracic echocardiography ( TTE), and transesophageal echocardiography (TEE). Oxypolygelatine caus ed a significantly higher number of microbubbles in the right atrium a nd MCA than did the saline solution, leading to a greater diagnostic r eliability of TCD (paired t test, p < 0.001). Coughing did not provoke right-to-left cardiac shunts (chi(2) analysis, p < 0.001). The techni que used for carrying out Valsalva's maneuver was important for the de tection of right-to-left cardiac shunts. Twenty-five right-to-left shu nts were diagnosed with TCD and 18 with TTE (36 vs 26%; chi(2) analysi s, p = 0.1). The findings indicate that TCD when properly done is high ly sensitive and specific for the diagnosis of right-to-left cardiac s hunts.