Parameters Related to Pulmonary Venous Flow Velocity in patients with Acute Myocardial Infarction

Joo, Seung Jae; Kim, Bok Kun; Yoo, Ho Dae; Hong, Kwan Pyo; Cha, Tae Joon; Lee, Jae Woo

Abstract

BACKGROUND
The mechanism for generating pulsatile flow in the pulmonary veins is related to a multitude of factors, including left atrial contraction and relaxation, mitral annular motion, and left ventricular svstolic and diastolic function. But factors affecting pulmonary venous flow velocity under left venticular dysfunction may be different from those under normal left ventricular function. We studied about parameters related to pulmonary venous flow velocity in patients with acute myocardial infarction. To assess left atrial function, we used the automated border detection echocardiography. METHOD: Twenty six patients(mean age 60±10) underwent echocardiographic examination 7 to 14 days after acute myocardial infarction. Twenty healthy persons(mean age 57±12) were served as a control group. Various indexes were obtained with M-mode, two-dimensional, pulsed Doppler, and automated border detection echocardiography.
RESULTS
1) Cardiac index and left ventricular ejection fraction were lower in patients. Patients had higher peak mitral flow velocity at atrial contraction(A velocity), lower E/A ratio, and longer left ventricular isovolumic relaxation time, which suggested the left ventricular relaxation abnormality. Diastolic time-velocity intergral of pulmonary venous flow was smaller in patients. Patients had a greater extent of left atrial area decrease resulting from atrial contraction. 2) Peak systolic velocity of pulmonary venous flow was related to left atrial expansion index(r=0.42), left atrial emptying index(r=0.39), end-diastolic area of left atrium(r=âˆ’0.29). left atrial atra decrease resulting from atrial contraction(AC;r=0.33), ejection fraction(r=0.39), and cardiac index(r=0.34) in the total group. In patient group, only left atrial expansion index(r=0.60), left atrial emptying index(r=0.59), and AC(r=0.55), from which the left atrial function can be estimated, were related and, in control group, only ejeciton fraction(r=0.55) and cardiac index(r=0.46) were related. Systolic time-velocity integral of pulmonary venous flow showed relations with heart rate(r=âˆ’0.38), regional wall motion score of left ventricle(r=âˆ’0.36), and ejection fraction(r=0.44) in the total group : heart rate(r=âˆ’0.47) and ejeciton fraction(r=0.44) in patient group : and age(r=0.53) in control group. 3) Peak diastolic velocity of pulmonary venous flow showed correlations with peak early mitral flow velocity(E velocity : r=0.58), A velocity(r=âˆ’0.34), E/A ratio(r=0.69), left ventricular isovolumic relaxation time(r=âˆ’0.48), deceleration time(r=âˆ’0.37), left atrial area decrease resulting from rapid ventricular filling(D : r=0.42), AC(r=âˆ’0.31), and D/AC ratio(r=0.61) in the total group, which suggested that peak diastolic velocity is determined by the same factors that influence the mitral flow velocity curves. Peak systolic velocity was related to age(r=âˆ’0.57).Patient group revealed the same findings except that cardiac index(r=0.40) was also related. Diastolic time velocity integral of pulmonary venous flow was related to heart rate(r=âˆ’0.39) and regional wall motion score of left ventricle(r=âˆ’0.33) in addition to the parameters affecting peak diastolic velocity. 4) Peak reverse flow velocity in pulmonary vein associated with atrial contraction was related to cardiac index(r=0.42), A velocity(r=0.43), and AC(r=0.41) in the total group. But correlation with AC was absent in control group.
CONCLUSION
The determinants of peak systolic velocity of pulmonary venous flow were left atrial contraction and relaxation in patients with acute myocardial infarction, and cardiac index and left ventricular ejection fraction in normal controls. On the other hand, peak diastolic velocity of pulmonary venous flow was determined by the same factors that influence the mitral flow velocity curves in both groups. Systolic and diastolic time-velocity integrals showed somewhat different patterns from peak velocities because of their relation to heart rate. Peak reverse flow velocity in pulmonary vein associated with atrial contraction was influenced by contractility of left atrium and caridiac index in patients with acute myocardial infarction, but mainly by cardiac index in normal controls.