Z. Tian

Impact of congenital heart disease on cerebrovascular blood flow dynamics in the fetus.

Neurological abnormalities are present in some children after repair of congenital heart disease (CHD). Recently, structural brain abnormalities have been identified in infants prior to cardiac surgery. By altering in utero blood flow patterns, the type of CHD may impact upon cerebrovascular flow dynamics prior to birth. We sought to determine whether left‐ and right‐sided obstructive congenital heart lesions modify cerebrovascular flow dynamics in the fetus.

Quantitative assessment of myocardial tissue velocities in normal children with Doppler tissue imaging

Assessment of myocardial tissue velocities in children in feasible with DTI. We have described normal velocity values for left ventricular motion in children during systole and diastole, at the mitral annulus, and at the posterior wall. The pattern of mitral annular motion in diastole mimics that of mitral blood inflow, whereas the pattern of posterior wall motion differs and may provide for a new form of assessment of diastolic function. Further investigation of myocardial velocities in states of volume and pressure overload, as seen in various forms of congenital heart disease, is warranted.

Acute Cardiovascular Effects of Fetal Surgery in the Human

Background—Prenatal surgery for congenital anomalies can prevent fetal demise or alter the course of organ development, resulting in a more favorable condition at birth. The indications for fetal surgery continue to expand, yet little is known about the acute sequelae of fetal surgery on the human cardiovascular system. Methods and Results—Echocardiography was used to evaluate the heart before, during, and early after fetal surgery for congenital anomalies, including repair of myelomeningocele (MMC, n=51), resection of intrathoracic masses (ITM, n=15), tracheal occlusion for congenital diaphragmatic hernia (CDH, n=13), and resection of sacrococcygeal teratoma (SCT, n=4). Fetuses with MMC all had normal cardiovascular systems entering into fetal surgery, whereas those with ITM, CDH, and SCT all exhibited secondary cardiovascular sequelae of the anomaly present. At fetal surgery, heart rate increased acutely, and combined cardiac output diminished at the time of fetal incision for all groups including those with MMC, which suggests diminished stroke volume. Ventricular dysfunction and valvular dysfunction were identified in all groups, as was acute constriction of the ductus arteriosus. Fetuses with ITM and SCT had the most significant changes at surgery. Conclusions—Acute cardiovascular changes take place during fetal surgery that are likely a consequence of the physiology of the anomaly and the general effects of surgical stress, tocolytic agents, and anesthesia. Echocardiographic monitoring during fetal surgery is an important adjunct in the management of these patients.

Vasoreactive response to maternal hyperoxygenation in the fetus with hypoplastic left heart syndrome.

Background—Cardiopulmonary interactions play an important role in the pathophysiology of hypoplastic left heart syndrome (HLHS). Pulmonary vasculopathy has been identified, especially in those with restrictive/intact atrial septum. Responsiveness of the pulmonary vasculature to maternal hyperoxygenation (MH) may provide a tool to assess the degree of pulmonary vasculopathy present before birth. Methods and Results—Doppler echocardiography was performed in 27 normal and 43 HLHS fetuses. In HLHS, sampling was repeated after 10 minutes of MH with 60% FiO2 and after 5 minutes of recovery. Sampling was performed in the proximal, midportion, and distal branch pulmonary artery (PA). Pulsatility index (PI) was used as a measure of vascular impedance. Of the HLHS fetuses, 34 had an open interatrial septum and 9 had a restrictive/intact atrial septum. At birth, 5 fetuses underwent immediate intervention on the interatrial septum. Middle cerebral artery PI was lower in HLHS versus normal fetuses (P<0.001). There was no difference in UA, DA, or branch PA PI between normal fetuses and those with HLHS. MH led to a significant decrease in PI at each of the PA sites sampled in fetuses with an open atrial septum (P<0.001); however, there no was significant change in the PI in fetuses that required immediate intervention on the atrial septum at birth. Using a cutoff value of <10% vasoreactivity, the sensitivity of MH testing for determining need for immediate intervention at birth is 100% (0.46 to 1.0); specificity, 94% (0.78 to 0.99); positive predictive value, 71% (0.30 to 0.95); and negative predictive value, 100% (0.86 to 1.0). No untoward effects were seen with MH. Conclusions—PA vasoreactivity to MH occurs in the fetus with HLHS. MH testing accurately identifies fetuses requiring urgent postnatal intervention at birth and may be used to select candidates for fetal atrial septoplasty.

Right Ventricular Performance in the Fetus With Hypoplastic Left Heart Syndrome

BACKGROUND In the fetus with hypoplastic left heart syndrome (HLHS), the single right ventricle (RV) pumps the entire cardiac output in utero. By investigating RV performance in utero, we sought to determine the inherent capabilities of a single RV before the increased metabolic demands of postnatal life and surgical palliation. In addition, we sought to determine whether the presence or absence of a left ventricular cavity impacts on RV performance in fetal life. METHODS Between November 2004 and December 2006, Doppler flow-derived measures of ventricular performance were obtained with echocardiography in 76 fetuses with normal cardiovascular system and in 48 age-matched fetuses with HLHS from 17 weeks until 40 weeks of gestation. The myocardial performance index, ventricular ejection force, and cardiac output were determined for both groups and compared using unpaired Students t tests and regression analysis. RESULTS In fetuses with HLHS, cardiac output was diminished by 20%, RV ejection force was elevated, and RV myocardial performance index was elevated compared with those of normal fetuses. The presence of a left ventricular cavity did not impact on RV performance in utero. CONCLUSIONS Fetuses with HLHS have preserved systolic performance but impaired diastolic performance compared with normal fetuses. The heart of a fetus with HLHS is less efficient than the normal heart in that ejection force of the RV is increased, but overall delivery of cardiac output is lower than normal. We conclude that patients with HLHS have inherent limitations in cardiac performance even before birth.

Impact of altered loading conditions on ventricular performance in fetuses with congenital cystic adenomatoid malformation and twin-twin transfusion syndrome

In the fetus with a structurally normal heart, two conditions—giant chest mass, such as congenital cystic adenomatoid malformation (CCAM), and twin–twin transfusion syndrome (TTTS)—alter ventricular loading conditions and may result in cardiovascular compromise. The aim of this study was to elucidate the mechanism of cardiovascular dysfunction by comparing geometry‐independent, Doppler flow‐derived measures of ventricular performance in fetuses with altered loading conditions vs. those in normal fetuses.

Preliminary Investigations into a New Method of Functional Assessment of the Fetal Heart Using a Novel Application of ‘Real-Time’ Cardiac Magnetic Resonance Imaging

Objectives: Because of quantitative echocardiographic limitations of fetal ventricular volumes as well as poor windows, we sought to determine if real-time magnetic resonance imaging (MRI) could be used. Methods: Real-time, functional, true fast imaging with steady-state precession, cardiac MRI was performed on 2 fetuses (one with hypoplastic left heart syndrome and one with ductal constriction). Fetal echocardiography was performed and cardiac index by Doppler was used to validate volume measures by MRI. Results: This technique was able to visualize the beating heart and assess ventricular volumes. Cardiac index and assessment of right ventricular hypertrophy and dilation by echocardiography were consistent with the ventricular volumes and right ventricular hypertrophy obtained by cardiac MRI. Conclusion: Real-time, functional fetal cardiac MRI is possible and can be used to quantitatively assess ventricular volumes and cardiac index in utero.

Parental decision-making in congenital heart disease.

OBJECTIVE To explore whether prenatal diagnosis of congenital heart disease is associated with lower levels of parental distress and greater satisfaction with decisions about cardiothoracic surgery when compared to postnatal diagnosis. METHODOLOGY A combined quantitative-qualitative design was used. Participants included the parents of 31 neonates (30 mothers and 22 fathers) admitted to the cardiac intensive care unit between 1 November 2001 and 1 May 2002 for repair of congenital cardiac malformations. Participants completed self-report measures of anxiety, optimism, and life events pre-operatively, and semi-structured qualitative interviews assessing satisfaction with decision-making within 1 week of the operation. RESULTS At the time of surgery, mothers of neonates receiving the diagnosis prenatally did not differ from mothers of neonates receiving the diagnosis postnatally on measures of anxiety, optimism, and life events. Fathers of neonates receiving the diagnosis prenatally, however, reported more optimism, lower state and trait anxiety, and fewer negative life events than fathers of neonates receiving the diagnosis postnatally. When we analyzed the interviews, we found that, regardless of the timing of the diagnosis, parents felt as though they made a genuine choice for their baby to have surgery. CONCLUSIONS In this pilot study, fathers who learned prenatally that their child had a congenital cardiac malformation were less distressed than those who discovered this fact only postnatally. From the parental perspective, nonetheless, distress and urgency do not impair their ability to make decisions about neonatal cardiac surgery.

Left ventricle to right ventricle size discrepancy in the fetus: the presence of critical congenital heart disease can be reliably predicted.

BACKGROUND Prenatal ventricular size discrepancy with disproportionately smaller left ventricle than right ventricle (L-R/VD) can be a marker for important left-sided structural heart disease in the newborn. METHODS We reviewed the echocardiograms of all fetuses evaluated at our center with L-R/VD from July 1, 2004 to January 1, 2008. RESULTS Of the 35 fetuses, 20 (57%) had critical arch obstruction and underwent neonatal intervention (group 1); 15 (43%) did not require newborn intervention (group 2). Ratios comparing left with right heart structures were significantly lower in group 1 fetuses compared with group 2 fetuses. Aortic arch measurement <or= 3 mm was the most sensitive, and abnormal direction of atrial level shunting was the most specific measure to predict the need for neonatal aortic arch intervention. CONCLUSION Ratios expressing the magnitude of L-R/VD, direction of flow at the atrial septum, and measurements of the aortic arch help identify fetuses that will require neonatal intervention.

Comparative analysis of cerebrovascular resistance in fetuses with single‐ventricle congenital heart disease

We sought to determine whether the presence or absence of aortic obstruction impacts cerebrovascular resistance in fetuses with single‐ventricle (SV) congenital heart disease (CHD).