Stroke and minute distance in pregnancy: a longitudinal study using Doppler ultrasound

Abstract

Summary Using Doppler ultrasound directed at the aortic arch, stroke and minute distance were measured in 45 normal singleton pregnancies and compared with 42 controls. In the non‐pregnant controls, stroke distance was 5% more in the supine than in the left lateral position (P<0·01) and during pregnancy this relativity was maintained until 36 weeks gestation. In the supine and left lateral positions respectively, stroke distance was increased by 8% (both) at 4 weeks (P<0·05 and NS), by 14 and 11% at 8 weeks (P<0·001 and P<0·01) and showed a maximum increase of 21 and 20% at 16 weeks gestation (both P<0·001). At 40 weeks, supine stroke distance was 14% less than the non‐pregnant control value (P<0·001), and 6% less than the value in the left lateral position (P<0·05), which was itself not significantly different from that in the non‐pregnant controls. The maximum increase of heart rate was at 32 weeks, by 24% in the supine and by 19% in the left lateral position (both P<0·001). Minute distance was maximally increased by 37% in the supine at 16 weeks (P<0·001) and by 30% in the left lateral position at 24 weeks (P<0·001). Thereafter, minute distance, measured in both positions, declined until at 40 weeks it was not significantly different from the non‐pregnant control value.

Cardiac structure and function in normal pregnancy

“…Patient characteristics such as age, ethnicity, parity, body surface area (BSA), body mass index (BMI) and height have been shown to independently affect cardiac function and structure [6][7][8][9][10][11][12][13][14][15]. Cardiac output (CO) has been reported to decline with advancing age in nonpregnant individuals, and this has been confirmed in pregnancy [6][7][8].…”

Management of Pregnancy in Patients With Complex Congenital Heart Disease: A Scientific Statement for Healthcare Professionals From the American Heart Association

“…Third Trimester (28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42) Weeks) The frequency of cardiac evaluation in late pregnancy must be individualized. Once the peak hemodynamic load of pregnancy is reached, normal symptoms of pregnancy (edema, dyspnea on exertion) may worsen, so patients must be monitored closely to distinguish such symptoms and signs of normal pregnancy from those that may reflect hemodynamic compromise.…”

“…[24][25][26][27][28][29][30][31][32][33] Maternal cardiac output increases 30% to 50% in a singleton pregnancy, with an additional 10% to 20% increment in a twin pregnancy. [34][35][36][37] Maternal posture can significantly affect cardiac output, especially after 20 weeks' gestation when the gravid uterus compresses the vena cava and pelvic veins.…”

Determination of the minimum number of cardiac cycles necessary to ensure representative blood flow velocity measurements

“…Estimation of the Doppler signal spectrum is improved by using the traditional method of averaging several cardiac cycles. However, authors still use a wide variety of numbers of cardiac cycles for calculations of blood flow indices, from two [15] to ten [1,13] or even more [14]. If only a small number of cardiac cycles is used for the mean value calculation, there can be differences in the interpretation of the normal values of the calculated indices due to the high individual variability.…”

“…However, the question still remains open as to the optimal number of cardiac cycles necessary for calculation of representative values of blood flow velocity indices. The table presents data on cardiac cycles used by different authors to calculate the pulsatility index (PI), the resistance index (RI) and other blood flow velocity waveform indices [1,6,7,13,14,15,17,19,20,21]. As we see from the table, there is a wide variation in the number of cycles used for calculations.…”