Coronary Doppler intensity changes during handgrip: new method to detect coronary vasomotor tone in coronary artery disease

OBJECTIVES This study evaluates whether quantitative measurement of Doppler intensity during handgrip may disclose coronary vasomotor dysfunction in patients with coronary artery disease (CAD). BACKGROUND Atherosclerotic coronary segments show an exaggerated constrictive response to handgrip. The intensity of the scattered Doppler signal is proportional to the number of blood cells flowing through the vessel, and should be reduced during vasoconstriction. Therefore, changes in coronary flow during handgrip may be detected by measuring Doppler intensity rather than velocities. METHODS The distal left anterior descending coronary artery (LAD) was imaged by high-resolution transthoracic color Doppler echocardiography during handgrip in 47 patients: 15 with normal coronary arteries and 32 with significant CAD involving the LAD. The Doppler signal was acquired at 70 dB dynamic range at baseline, 30-s handgrip and 5 min recovery. Peak and mean flow velocity, pressure half-time, deceleration time (ms), deceleration rate (cm/s2) and mean gray level intensity (intensity units [IU]) of the Doppler spectrum were measured in diastole. RESULTS The velocity parameters did not change significantly during handgrip both in normal and CAD patients. The Doppler intensity significantly decreased during handgrip (from 87.0 ± 32.8 to 57.7 ± 35.3 IU; p < 0.001) in patients with CAD, and it increased or remained unchanged in normals (from 74.1 ± 27.3 to 85.1 ± 31.2 IU; p = NS). The sensitivity of Doppler intensity in detecting CAD was 84.4%, specificity 93.3%, negative predictive value 73.7% and positive predictive value 96.4%. CONCLUSIONS Doppler intensity measured by transthoracic echocardiography during handgrip allows the detection of CAD and coronary vasomotor dysfunction.