Transthoracic Doppler color imaging of the blood flows in the left coronary septal branches

: This study characterized blood flow signals derived from the left coronary septal branches by transthoracic Doppler color flow imaging. In the anterior ventricular septum, the signal was detected in 7 of 13 patients with aortic stenosis, 8 of 34 with hypertrophic cardiomyopathy, and 5 of 144 patients with other diseased states. The peak diastolic flow velocity assessed by a pulsed Doppler technique ranged 21-115 cm/s (mean 57). Systolic signal was depicted in 13 of the 20 with the diastolic signal, indicating retrograde flow direction in all of them. The peak negative systolic component ranged 11-80 cm/s (mean 40). Peak diastolic flow velocity of the left anterior descending artery was higher in patients with the septal branch flow signal than in those without the signal (53 +/- 24 vs 31 +/- 11 cm/s). Patients with the signal showed larger transvalvular pressure gradient in aortic stenosis, and greater septal thickness in hypertrophic cardiomyopathy than in those without the signal. In conclusion, transthoracic visualization of the septal branch flow signal by Doppler color flow mapping is attributable to increased coronary blood flow at rest which is probably due to excessive load and/or septal hypertrophy. Augmented systolic retrograde flow may play additional role in the diastolic high velocity flow in the septal perforator.