HE INCREASE of pulse wave velocity with age is well established1-3 and reflects a loss of the elastic properties of the arterial wall.4 The age trends of pulse wave velocity vary for different arteries.2 8 In view of early localization of atherosclerotic changes in the abdominal aorta, we have compared age trends of the aortic pulse wave velocity, measured by impedance plethysmography in normal subjects and in patients with coronary artery disease. Since arterial hypertension as well as age increases the pulse wave velocity,1-6 only normotensive patients were selected for this series. Impedance plethysmography is a convenient method for inertia-free recording of the aortic volume pulse from skin electrodes and eliminates the necessity of intrapolation of records from the subelavian or carotid arteries as in earlier investigations.We have also measured the interval from the earliest QRS deflection in any of simultaneous 3 standard electrocardiographic leads to the foot point of the aortie volume pulse recorded by impedance plethysmogram. This interval consists of the electrical latent period, the period of isometric contraction, and the time from the opening of the aortic valve to the arrival of the pulse wave in the vicinity of the aortic arch. The isometric contraction time is probably the most important of these components. The term "aortic ejection time"7 is used for abbreviation. The effects of age and of coronary artery disease on this interval was studied for the first time.

Objective To investigate time intervals of the ductus venosus (DV) flow velocity waveform (FVW) and those of the cardiac cycle that correspond with each DV-FVW component in fetuses with intrauterine growth restriction (IUGR) due to placental insufficiency. Methods

Objectives To investigate time-interval variables of ductus venosus (DV) flow velocity waveforms (FVWs) in twin-to-twin transfusion syndrome (TTTS), comparingthe results with reference ranges from normal singleton fetuses. The impact of laser surgery and the effect of prognostic factors were also evaluated. S and D, respectively). For each variable, Z-scores were calculated with respect to previously reported normal reference ranges. Methods In 107 TTTS cases, DV-FVWs of both recipients and donors were recorded 1 day before and 2 days after laser therapy. Time intervals for systolic (S) and early diastolic (D) peaks were analyzed retrospectively with regard to acceleration time (acc-S and acc-D for S and D, respectively) and deceleration time (dec-S and dec-D for Results Z-scores for all variables showed statistically significant differences from those observed previously in normal fetuses, with the exception of dec-S of donors. The most striking differences were observed in longer dec-S of recipients (P < 0.001) and longer dec-D of donors (P < 0.001). Laser therapy showed significant impact on dec-S and acc-D in recipients and on all variables in donors.Regarding the short-term prognosis, acc-S and dec-S showed significant differences for the prediction of intrauterine fetal demise in donors (P = 0.009 and P = 0.011, respectively). Conclusion

With advancing gestational age, prolongation of the diastolic phase of DV-FVW and of the E-wave of tricuspid flow was observed, suggesting maturation of ventricular diastolic function. Time-related analysis of Doppler signals of DV-FVW may provide detailed insights into fetal cardiac function.

Characteristic differences between right and left ventricles were found in the reference ranges, suggesting the developmental properties of the fetal heart. © 2014 John Wiley & Sons, Ltd.