Alterations in Cardiac Output in Fetuses with Congenital Heart Disease

A Comparison of Perinatal Circulatory Transition in Critical Right and Left Heart Obstructive Lesions

BACKGROUND

During perinatal transition in hypoplastic left heart syndrome (HLHS), reduced systemic blood flow (Qs) and cerebral blood flow and increased pulmonary blood flow (Qp) are observed, contributing to hemodynamic instability. The aim of the present study was to explore whether similar or discordant perinatal changes occur in critical pulmonary outflow tract obstruction (POFO) compared with HLHS and healthy control subjects.

METHODS

Echocardiography was prospectively performed at 36 to 39 gestational weeks and then serially from 6 to 96 hours after birth, before cardiac intervention. Combined cardiac output (CCO), superior vena cava (SVC) flow rate, Qs and Qp, and resistance indices (RIs) in the middle cerebral artery (MCA), celiac artery, and superior mesenteric artery were compared among the three groups.

RESULTS

In fetal POFO (n = 19) and HLHS (n = 31), CCO was comparable with that in control subjects (n = 21) because of elevated stroke volume, but CCO in POFO was lower compared with HLHS (P < .01). Compared with control subjects, POFO CCO was lower at 6 hours after delivery but comparable at 24 to 96 hours. In contrast, from 6 to 96 hours, the HLHS group had higher CCO than POFO and control subjects. Compared with control subjects, both neonates with POFO and those with HLHS had lower Qs and SVC flow (POFO at 24 hours, P < .001; HLHS 6-hour Qs and 6- to 24-hour SVC flow). Compared with control subjects, Qp was increased in POFO at 48 to 96 hours (P < .05) and in HLHS at all time points (P < .001). Compared with fetal MCA RI, postnatal MCA RI was acutely higher in both POFO and HLHS, whereas in control subjects, it tended to decrease postnatally. Celiac artery RI and superior mesenteric artery pulsatility index were higher in POFO and HLHS from 6 to 48 hours vs control subjects.

CONCLUSIONS

POFO and HLHS demonstrate divergent acute hemodynamic changes in the early neonatal period, with early decreased CCO in POFO and increased CCO in HLHS. Both demonstrate early compromise in Qs and SVC (cerebral flow) and ongoing altered splanchnic flow.

Cardiovascular Effects of a Thoracoamniotic Shunt in a Fetus Affected by Isolated Right Congenital Diaphragmatic Hernia and Hydrops

A thoracoamniotic shunt was placed in a fetus affected by a right congenital diaphragmatic hernia (RCDH) complicated by voluminous nonimmune hydrops (NIH) at 30 weeks of gestation. The fetus showed congestive cardiac failure with a combined cardiac output (CCO) of 460.7 ml/min (Z-score: -1.2). After seven days, no edema, ascites, or pleural effusion was present. CCO increased significantly, reaching a Z-score of -0.2, as well as right and left cardiac output (Z-scores: -0.3 and -0.8, respectively). Two weeks later, the cardiac function and the ascites got worse despite the correct shunt placement, suggesting a possible occlusion. At 33 weeks, a C-section was performed due to labor in breech presentation. Despite the intensive care provided, the newborn died due to pulmonary hypertension and respiratory insufficiency. The thoracoamniotic shunt's effect on fetal circulation and the mechanisms of NIH in the event of RCDH are still unclear. Due to the high mortality rate of this condition and its poorer outcomes compared to left-sided defects, shunting cannot be considered an efficient attempt to improve fetal and neonatal survival rates to date. A close relationship between the amount of lymphatic effacement and cardiac function is clear, but further studies are needed to provide more information about this severe condition and its treatment.

Advanced imaging of fetal cardiac function

Over recent decades, a variety of advanced imaging techniques for assessing cardiovascular physiology and cardiac function in adults and children have been applied in the fetus. In many cases, technical development has been required to allow feasibility in the fetus, while an appreciation of the unique physiology of the fetal circulation is required for proper interpretation of the findings. This review will focus on recent advances in fetal echocardiography and cardiovascular magnetic resonance (CMR), providing examples of their application in research and clinical settings. We will also consider future directions for these technologies, including their ongoing technical development and potential clinical value.