Objective:We developed a noninvasive Doppler technique for measuring fetal cardiac isovolumetric contraction time (ICT). The purpose of this study was to determine how well our method real cardiac performance using fetal lamb as an instrumented model.
Methods:The true ICT was measured by simultaneous recording of the pressure waves of the left ventricle and ascending aorta. The maximum first derivative of the left ventricular pressure wave (Max dp/dt) was calculated. The Doppler ICT was measured in the apporpriately filtered Doppler cardiac signals. Positive and negative inotropic agents were administered to change the cardiac contractility.
Results:There was an inverse relationship between the Doppler ICT and the Max dp/dt. Excellent linear correlation was found an absolute value and changes from control value between the true ICT and the Doppler ICT (r = 0.959, r = 0.62).
Conclusion:The Doppler ICT measurement provides useful information about changes in ventricular performance.
1. Frank M, Kinalw W. Indirect measurement of isovolumic contraction time and tension period in normal subjects. Am J Cardiol1996;10:800-806.
2.
2. Harris LC, Weissler AM, Manske AO, Danford BH, White GD, Hammil WA. Duration of the phases of mechanical systole in infants and children. Am J Cardiol1964;14:448-455.
3.
3. Weissler AM, Harris WS, Schoenfeld CD. Systolic time intervals in heart failure in man. Circulation1968;37:149-159.
4.
4. Metzger CC, Chough CB, Kroetz FW, Leonard JJ. True isovolumetric contraction time. Its correlation with two external indexes of ventricular performance. Am J Cardiol1970;25:434-442.
5.
5. Wolfson RN, Zador IE, Pillay SK, Timor-Tritsch JE, Hertz RH. Antenatal investigation of human fetal systolic time intervals. Am J Obstet Gynecol1977;129:203-207.
6.
6. Murata Y, Martin CB, Ikenoue T, Lu PS. Antepartum evaluation of the pre-ejection period of the fetal cardiac cycle. Am J Obstet Gynecol1978;132:278-284.
7.
7. Organ LW, Bernstein A, Hawrylyshyn PA. The preejection period as an indicator of fetal well-being. Am J Obstet Gynecol1980;137:810-819.
8.
8. Koga T, Athayde N, Trudinger B, Nakano H. A new and simple Doppler method for measurement of fetal cardiac isovolumetric contraction time. Ultrasound Obstet Gyncol2001;18:264-267.
9.
9. Koga T, Athayde N, Trudinger B. The fetal cardiac isovolumetric contraction time in normal pregancy and in pregnancy with placental vascular disease: The first clinical report using a new ultrasound technique. Br J Obstet Gynecol2001;108:179-185.
10.
10. De Muylder X, Fouron JC, Bard H, Riopal L, Urfer F. Thedifference between the systolic time intervals of the left and right ventricles during fetal life. Am J Obstet Gynecol1984;149:737-740.
11.
11. Riemenchneider TA, Ruttenberg HD, Adams FH. Maturational changes in left and right ventricular electromechanical intervals in the newborn lamb. Cardiovasc Res1979;12:228-238.
