[Left ventricular wall stress and contractile function immediately after arterial switch operation in neonates].
Dynamic changes in left ventricular function immediately after arterial switch operation in neonates are poorly understood. Accordingly we determined left ventricular end-systolic wall stress (ESWS) and rate corrected mean velocity of fiber shortening (mVcfc) by echocardiography immediately after arterial switch operation in the intensive care unit (ICU) in 11 neonates. Stress-velocity index (S-V Index: number of standard deviations from the population mean mVcfc for ESWS) was calculated from the ESWS-mVcfc relation as a load independent index of myocardial contractility. The dicrotic notch of radial arterial wave form was used to determine the end-systolic pressure (radial Pes). Left ventricular ejection time was obtained from the pulse Doppler wave form sampled from the ascending aorta. Mean ESWS after the operation was 37.8 +/- 17.3 g/cm2 (mean +/- SD) and mean S-V index was normal (0.80 +/- 3.11). S-V index was normalized within 12 hours after operation in 9 cases. In one case, which showed acute heart failure because of accidentally elevated afterload just after pump perfusion, S-V index had not recovered until 24 hours after operation. In another case, preoperative LV/RV pressure ratio was 0.63 and resulted in prolonged low level of S-V index. Preoperative conditions of left ventricle were compared with postoperative ESWS and S-V index. Preoperative end-diastolic posterior wall thickness of left ventricle (LVPWTd) was correlated with postoperative S-V index (r = 0.74, p = 0.015). Preoperative LVPWTd/LVDd (end-diastolic internal diameter of left ventricle) ratio was inversely correlated with postoperative ESWS (r = 0.66, p = 0.037) and correlated with S-V index (r = 0.80, p = 0.006). Preoperative LV/RV pressure ratio showed correlation with S-V index (r = 0.67, p = 0.023).(ABSTRACT TRUNCATED AT 250 WORDS)
Koide
M
M
Department of Pediatric Cardiovascular Surgery, Tokyo Women's Medical College, Japan.
D004452:Echocardiography; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009200:Myocardial Contraction; D013318:Stroke Volume; D014188:Transposition of Great Vessels / Q000000981:diagnostic imaging / Q000601:surgery*; D016277:Ventricular Function, Left / Q000502:physiology*