Influences of pericardium and actue myocardial ischemia on pulmonary venous floe dynamics and left atrial function

Influences of pericardium and actue myocardial ischemia on pulmonary venous flow (PVF) dynamics and left atrial (LA) function were studied in 13 anestietized open-shest dogs. PVF velcity was measured by Dopperl flow probe instataneously with LA diameter, left ventricular (LV) segment lengths in control and ischemic regions using ultrasonic dimension gauges. LA and LV pressures were also measured simultaeously with PVF velocity using Miller's micromanometers. Recordings were made at control state and during actue myocardial ischmia produced by occlusion of the left circumflex coronary artery, with or without pericardium. When the pericardium was opened, the peak velocity of PVF deuring LA contraction (A wave) was increased (28.9 → 42.2cm/sec, p＜0.01) in proportion as LV chamber compliance increaed. Moreover, opening the pericardium, the velocity-time integral of PVF in the systolic phases(S wave) was invreased (12.6 → 14.2 cm, p＜0.05), associated with the sift of LA pressure-volume relation to the right. These findings suggested that LV compliance was one of important determinants of the A wave, and that the increase in the S wace (increase in the reservoir function of LA) by opening the pericardium might be attributed to the increase in LA chamber compliance. After actue myocardial ischemia, PVF I the diastolic phase (D wave) was decreased (12.3 → 9.8cm, p＜0.01), whereas S wace remained unchanged owing to the aufmentation of LA pump function under the myocardial ischemia. In addition, the D wave was significantly correlated with the time constant of LV pressure decline during the isocolumetric relaxation period (r＝-0.535, p＜0.01). These results indicate that LV and LA compliances altered by the existence of pericardium play an important role for determining A and S wave on PVF, and also LV diastolic property might be an important determinant of D wave on PVF.