Harada K, Takahashi Y, Tamura M, Ito T, Ishida A, Takada G
Department of Pediatrics, Akita University School of Medicine, Japan.
Int J Cardiol. 1996 Oct 25;56(3):227-33. doi: 10.1016/0167-5273(96)02753-2.
We studied effects of cardiac output on Doppler transmitral and transtricuspid flow velocities in 24 appropriate for gestational age premature infants. We measured peak flow velocity of early diastole (peak E) and atrial contraction (peak A), ratio of peak flow velocity of early diastole to atrial contraction (peak E/A), total flow velocity-time integral, the first third filling fraction, peak filling rate normalized to stroke volume, and deceleration time (DT). Cardiac output was calculated as the product of the aortic flow velocity-time integral, aortic valve area, and heart rate. The cardiac output increased significantly with advancing gestational age and body weight (r = 0.78 and 0.86, P < 0.01, respectively). With increasing cardiac output, the transmitral as well as transtricuspid peak E, peak E/A, and total flow velocity-time integral increased significantly without any change in the peak filling rate normalized to stroke volume, peak A, and deceleration time. The transmitral as well as transtricuspid peak E did not correlate with the heart rate. Although these results do not establish whether changes in ventricular relaxation process or in cardiac output is responsible for the progressive increase in the peak E and peak E/A. Unchanged peak filling rate normalized to stroke volume of the left and right ventricles suggest that changes in cardiac output with maturity is, in fact, one of the important contributory factors. This evidence should be borne in mind in interpreting ventricular diastolic filling as an index of ventricular diastolic function in premature infants.
我们研究了心输出量对24例适于胎龄早产儿多普勒二尖瓣和三尖瓣血流速度的影响。我们测量了舒张早期峰值流速（E峰）和心房收缩期峰值流速（A峰）、舒张早期峰值流速与心房收缩期峰值流速之比（E/A峰）、总流速时间积分、前三分之一充盈分数、每搏量标准化的峰值充盈率以及减速时间（DT）。心输出量通过主动脉流速时间积分、主动脉瓣面积和心率的乘积来计算。心输出量随着胎龄和体重的增加而显著增加（r分别为0.78和0.86，P<0.01）。随着心输出量增加，二尖瓣和三尖瓣的E峰、E/A峰以及总流速时间积分显著增加，而每搏量标准化的峰值充盈率、A峰和减速时间无变化。二尖瓣和三尖瓣的E峰与心率无关。虽然这些结果未确定心室舒张过程的变化还是心输出量的变化导致了E峰和E/A峰的逐渐增加。左右心室每搏量标准化的峰值充盈率不变提示，事实上心输出量随成熟度的变化是重要的促成因素之一。在将心室舒张期充盈作为早产儿心室舒张功能指标进行解读时应牢记这一证据。
