Reference Values for Fetal Cardiac Dimensions, Volumes, Ventricular Function and Left Ventricular Longitudinal Strain Using Doppler Ultrasound Gated Cardiac Magnetic Resonance Imaging in Healthy Third Trimester Fetuses

BACKGROUND

Recent advances in hardware and software permit the use of cardiac MRI of late gestation fetuses, however there is a paucity of MRI-based reference values.

PURPOSE

To provide initial data on fetal cardiac MRI-derived cardiac dimensions, volumes, ventricular function, and left ventricular longitudinal strain in healthy developing fetuses >30 weeks gestational age.

STUDY TYPE

Prospective.

POPULATION

Twenty-five third trimester (34 ± 1 weeks, range of 32-37 weeks gestation) women with healthy developing fetuses.

FIELD STRENGTH/SEQUENCE

Studies were performed at 1.5 T and 3 T. Cardiac synchronization was achieved with a Doppler ultrasound device. The protocol included T2 single shot turbo spin echo stacks for fetal weight and ultrasound probe positioning, and multiplanar multi-slice cine balanced steady state free precession gradient echo sequences.

ASSESSMENT

Primary analyses were performed by a single observer. Weight indexed right ventricular (RV) and left ventricular (LV) volumes and function were calculated from short axis (SAX) stacks. Cardiac dimensions were calculated from the four-chamber and SAX stacks. Single plane LV longitudinal strain was calculated from the four-chamber stack. Interobserver variability was assessed in 10 participants. Cardiac MRI values were compared against available published normative fetal echocardiogram data using z-scores.

STATISTICAL TESTS

Mean and SDs were calculated for baseline maternal/fetal demographics, cardiac dimensions, volumes, ventricular function, and left ventricular longitudinal strain. Bland-Altman and intraclass correlation coefficient analysis was performed to test interobserver variability.

RESULTS

The mean gestational age was 34 ± 1.4 weeks. The mean RV and LV end diastolic volumes were 3.1 ± 0.6 mL/kg and 2.4 ± 0.5 mL/kg respectively. The mean RV cardiac output was 198 ± 49 mL/min/kg while the mean LV cardiac output was 173 ± 43 mL/min/kg.

DATA CONCLUSION

This paper reports initial reference values obtained by cardiac MRI in healthy developing third trimester fetuses. MRI generally resulted in slightly larger indexed values (by z-score) compared to reports in literature using fetal echocardiography.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 2.

Cardiac Dimensions in Normal Pregnancy: A Prospective Study

BACKGROUND

Pregnancy, a unique physiologic state, is associated with several changes in the various body systems. The cardiovascular system is one of the systems affected, with chronic volume overload being one of the characteristic changes experienced during pregnancy. Cardiovascular disease in pregnancy is the leading cause of non-obstetric maternal death worldwide.

AIM

This study aims to determine and describe the changes in left and right ventricular and atrial sizes in systole and diastole in the course of normal pregnancy.

METHODS AND MATERIALS

A cohort study was conducted among healthy pregnant women between the age of 18 and 40 who attended the antenatal clinic of Federal Medical Centre (FMC), Yenagoa, Bayelsa State. Fifty women were recruited during the first trimester (T1) of pregnancy and followed up until six weeks postpartum. Ethical approval was obtained from the Research Ethics Committee of Federal Medical Centre, Yenagoa, with approval number FMCY/REC/ECC/2019/JAN/150. Clinical evaluation, hematologic, biochemical, and anthropometric assessments, and two-dimensional M-mode and Doppler echocardiography were done for the participants in each trimester of pregnancy and at six weeks postpartum. The clinical and echocardiographic parameters were analyzed using Statistical Package for the Social Sciences (SPSS) version 22.0 (IBM Corp., Armonk, NY, USA).

RESULTS

The mean trend of left ventricular posterior wall thickness in diastole (LVPWd) and left ventricular posterior wall thickness in systole (LVPWs) increased progressively from the first to third trimester (T3) (not statistically significant) but dropped toward initial values in postpartum to the level that was statistically significant for LVWPd alone when compared to baseline first trimester values. The left atrial diameter in systole (LADs) was largest in the third trimester, and the left atrial volume index (LAVI) and right ventricular basal diameter (RVD1) also showed a similar trend. The left ventricular internal diameter (LVID) in both systole and diastole increased progressively from the first to the third trimesters, but the increase was only statistically significant between the third trimester (T3) and the first trimester (T1). The right atrial diameter (RAD) and right atrial volume (RAV) also increased progressively from the first to the third trimesters, but the increase was only statistically significant between the third trimester (T3) and the first trimester (T1).

CONCLUSION

Changes were noticed in the cardiac chamber sizes during pregnancy. However, this reversed back to levels similar to the first trimester during the postpartum period. To aid in the early detection and treatment of cardiovascular disorders in pregnancy, screening of apparently healthy pregnant women who later developed complaints is advised as cardiovascular changes could be significant during pregnancy.

Correlation of echocardiographic parameters in prone and supine positions in normal adults using a novel approach

BACKGROUND

Transthoracic echocardiography (TTE) in prone position is challenging. Innovative use of transesophageal echocardiography (TEE) probe to perform TTE for such patients has been described; but reproducibility and correlation of the TTE measurements by this technique with those obtained by the standard supine TTE study are still unknown.

METHODS

We enrolled 30 non-COVID-19 individuals, with a mean (SD) age 35 (10.9) years and 11 females, to study the agreement between the transthoracic measurements of the left ventricular (LV), left atrial (LA), aortic dimensions, and ejection fraction (EF) obtained in prone position using an external TEE probe versus the standard supine position using the conventional TTE probe.

RESULTS

There were no significant differences between LV end-diastolic and end-systolic diameters, septal wall thickness, posterior wall thickness, and aortic root dimensions in the prone versus the supine positions, while the mean EF (60.3% vs 63.1%, P = .014) and mean LA dimensions (1.8 vs 1.9 cm/m² , P < .001) were significantly lower in the prone position. The mean time of scans was significantly longer in the prone as compared to the supine position (12.5 vs 4.5 minutes, P < .001). All supine studies had good quality while in the prone position four studies were of poor quality, and one was nondiagnostic.

CONCLUSIONS

Assessment of cardiac dimensions and systolic function in the prone position using transthoracic TEE probe was feasible. LV and aortic dimensions agreed well with the standard TTE in supine position; however, LA dimensions and EF were lower in the prone position.

Cardiac structure and function in humans: a new cardiovascular physiology laboratory

As the traditional cardiovascular control laboratory has disappeared from the first-year medical school curriculum, we have recognized the need to develop another "hands-on" experience as a vehicle for wide-ranging discussions of cardiovascular control mechanisms. Using an echocardiograph, an automatic blood pressure cuff, and a reclining bicycle, we developed protocols to illustrate the changes in cardiac and vascular function that occur with changes in posture, venous return, and graded exercise. We use medical student volunteers and a professional echocardiographer to generate and acquire data, respectively. In small-group sessions, we developed an interactive approach to discuss the data and to make a large number of calculations from a limited number of measurements. The sequence of cardiac events and cardiac structure in vivo were illustrated with the volunteers lying down, standing, and then with their legs raised passively above the heart to increase venous return. Volunteers were then asked to peddle the bicycle to achieve steady-state heart rates of 110 and 150 beats/min. Data were collected in all these states, and calculations were performed and used as the basis of a small-group discussion to illustrate physiological principles. Information related to a surprisingly large number of cardiovascular control mechanisms was derived, and its relevance to cardiovascular dysfunction was explored. This communication describes our experience in developing a new cardiovascular control laboratory to reinforce didactic material presented in lectures and small-group sessions.

Growth hormone treatment and left ventricular dimensions in Turner syndrome

OBJECTIVE

To determine whether cardiac dimensions were different in girls with Turner syndrome (TS) who received growth hormone (GH) compared with those who did not receive GH.

STUDY DESIGN

This retrospective, cross-sectional study analyzed echocardiograms in 86 females with TS divided into GH-treated (n = 67) and untreated (n = 19) groups. The subjects all participated in the National Institutes of Health protocol between 2001 and 2006.

RESULTS

The average age was 16.2 years (range, 10 to 25 years), and average duration of GH treatment was 4.4 years (range, 1 to 14 years). The GH-treated group was taller by approximately 7 cm (P = .004), but cardiac dimensions normalized to body surface area (BSA), including septal and posterior wall thickness and left ventricular (LV) mass and internal diameters, did not differ significantly between the 2 groups. The fractional shortening index was similar in the 2 groups. Multiple regression analyses indicated that BSA, but not duration of GH treatment, predicted LV dimensions in girls with TS.

CONCLUSIONS

GH treatment of girls with TS increases stature but does not disproportionately affect cardiac dimensions.

Cardiac effects of a single course of antenatal betamethasone in preterm infants

AIM

To show the effects of a single course of antenatal betamethasone on cardiac measurements and systolic functions in premature newborn infants.

METHODS

Seventy six newborn infants with a gestational age of 25-33 weeks were included in the study. They were first classified according to their gestational age: 25-29 weeks (n = 28) and 30-33 weeks (n = 48). They were then reclassified as betamethasone positive (mother received one course of betamethasone) or betamethasone negative (mother did not receive any antenatal glucocorticoid treatment). Cross sectional M mode echocardiographic scans were performed during the first three postnatal days and at the end of the first and third weeks. Left interventricular septum (IVS), left ventricular posterior wall (LVPW), left ventricular end diastolic (LVED), and left ventricular end systolic (LVES) dimensions, aortic root (AO), and left atrial diameters (LAs) were measured. The IVS to LVPW ratio was calculated to identify asymmetrical septal hypertrophy.

RESULTS

In neither group was any statistically significant difference noted in IVS, LVED, LVES, LVPW, LA, and AO measurements during the three cardiac ultrasonography scans. Systolic function, as assessed by fractional shortening, was not significantly different in infants who received betamethasone antenatally, in either age group. There was no difference in the IVS/LVPW ratios between those who received antenatal steroid and those who did not for the 25-29 week and 30-33 week groups during these three consecutive scans.

CONCLUSION

One course of antenatal betamethasone did not affect the cardiac wall thicknesses and systolic function in premature infants.