[Left intraventricular flow during isovolumic relaxation. Frequency, significance, mechanism].

Supplementary intraventricular flow during the left ventricular isovolumic relaxation period "isovolumic relaxation flow", was described for the first time in 1987 by Sasson. This flow was searched for in 13 patients with hypertrophic obstructive cardiomyopathy (HOCM), 58 patients with aortic valve stenosis (AVS) and 41 normal control patients. It was detected in 77% of patients with HOCM, 50% of patients with AVS and 5% of normal controls. The flow was usually recorded throughout the isovolumic relaxation period and lasted an average 104 ms (range 70 to 140 ms) with a velocity of 0.74 m/s (range 0.25 to 1.70 m/s). It was detected along the middle third of the interventricular septum, directed towards the cardiac apex, coded in red in colour Doppler studies. The other Doppler echocardiographic signs associated with isovolumic relaxation flow were: small left ventricular chambers, normo- or hyperkinetic wall motion, systolic apical cavity obliteration, intraventricular systolic acceleration with a left systolic peak (74% of cases) but with no correlation between the velocity of this flow and that of isovolumic relaxation flow. Isovolumic relaxation flow results from an intraventricular pressure gradient related to asynchronous relaxation and the resulting redistribution of blood in the left ventricle. It would seem to be a marker of hyperkinetic wall motion together with systolic apical cavity obliteration and the resulting intraventricular systolic accelerated flow. It should not be confused with the mitral E wave, especially in patients with atrial fibrillation.