Hypoplastic Left Heart Syndrome: Is There a Role for Fetal Therapy?

During fetal life some cardiac defects may lead to diminished left heart growth and to the evolution of a form of hypoplastic left heart syndrome (HLHS). In fetuses with an established HLHS, severe restriction or premature closure of the atrial septum leads to left atrial hypertension and remodeling of the pulmonary vasculature, severely worsening an already poor prognosis. Fetal therapy, including invasive fetal cardiac interventions and non-invasive maternal hyperoxygenation, have been introduced to prevent a possible progression of left heart hypoplasia, improve postnatal outcome, or secure fetal survival. The aim of this review is to cover patient selection and possible hemodynamic effects of fetal cardiac procedures and maternal hyperoxygenation in fetuses with an evolving or established hypoplastic left heart syndrome.

First-trimester screening for congenital heart disease.

UNLABELLED: Advances over the last decade in technology, training, and availability of prenatal care have led to a focus on the detection of congenital heart defects (CHD) and its prenatal management for improved pregnancy outcomes. First-trimester transvaginal heart screening is feasible and well tolerated. Due to advances in the diagnosis of trisomy by nonultrasound methods, a significant effort will now be focused on CHD detection in the first trimester of otherwise uncomplicated pregnancies. PURPOSE OF REVIEW: Detection of CHD is not being accomplished by heart screening training or postnatal protocols. First-trimester evaluation of fetuses is becoming more common, and a method of evaluation of the heart would improve selection of those who need later fetal echocardiography. RECENT FINDINGS: Equipment advances are resulting in excellent visualization of the fetal circulatory system even at 12­13 weeks, gestation. SUMMARY: Improved first-trimester fetal heart screening will result in a jump in CHD detection and in improved care of these patients during gestation and prior to their cardiac surgery.

Summary of the 2015 International Paediatric Heart Failure Summit of Johns Hopkins All Children's Heart Institute.

In the United States alone, ∼14,000 children are hospitalised annually with acute heart failure. The science and art of caring for these patients continues to evolve. The International Pediatric Heart Failure Summit of Johns Hopkins All Children's Heart Institute was held on February 4 and 5, 2015. The 2015 International Pediatric Heart Failure Summit of Johns Hopkins All Children's Heart Institute was funded through the Andrews/Daicoff Cardiovascular Program Endowment, a philanthropic collaboration between All Children's Hospital and the Morsani College of Medicine at the University of South Florida (USF). Sponsored by All Children's Hospital Andrews/Daicoff Cardiovascular Program, the International Pediatric Heart Failure Summit assembled leaders in clinical and scientific disciplines related to paediatric heart failure and created a multi-disciplinary "think-tank". The purpose of this manuscript is to summarise the lessons from the 2015 International Pediatric Heart Failure Summit of Johns Hopkins All Children's Heart Institute, to describe the "state of the art" of the treatment of paediatric cardiac failure, and to discuss future directions for research in the domain of paediatric cardiac failure.

Diagnosis and treatment of foetal heart failure: foetal echocardiography and foetal hydrops.

Foetal echocardiography has progressed to be able to diagnose many forms of CHD and to assess the prognosis of cardiac lesions based on their anatomy and presentation in utero. This article outlines a straightforward method for the rapid evaluation of foetus that may have congestive heart failure with or without hydrops and for the differentiation of the pre-hydropic state from normal. The presence of signs of foetal heart failure, such as cardiomegaly or valvular regurgitation, gives clues to the aetiology of hydrops. The assessment of the prognosis of hydrops foetalis can be difficult but can be aided by the use of the cardiovascular profile score. Once identified, the neurohumoral effects of foetal heart failure can be ameliorated using transplacental digoxin if the hydrops has not progressed.

Variation in Prenatal Diagnosis of Congenital Heart Disease in Infants.

BACKGROUND AND OBJECTIVE: Prenatal diagnosis allows improved perioperative outcomes for fetuses with certain forms of congenital heart disease (CHD). Variability in prenatal diagnosis has been demonstrated in other countries, leading to efforts to improve fetal imaging protocols and access to care, but has not been examined across the United States. The objective was to evaluate national variation in prenatal detection across geographic region and defect type in neonates and infants with CHD undergoing heart surgery. METHODS: Cardiovascular operations performed in patients ≤6 months of age in the United States and included in the Society of Thoracic Surgeons Congenital Heart Surgery Database (2006-2012) were eligible for inclusion. Centers with >15% missing prenatal diagnosis data were excluded from the study. Prenatal diagnosis rates were compared across geographic location of residence and defect type using the χ(2) test. RESULTS: Overall, the study included 31,374 patients from 91 Society of Thoracic Surgeons Congenital Heart Surgery Database participating centers across the United States. Prenatal detection occurred in 34% and increased every year, from 26% (2006) to 42% (2012). There was significant geographic variation in rates of prenatal diagnosis across states (range 11.8%-53.4%, P < .0001). Significant variability by defect type was also observed, with higher rates for lesions identifiable on 4-chamber view than for those requiring outflow tract visualization (57% vs 32%, P < .0001). CONCLUSIONS: Rates of prenatal CHD detection in the United States remain low for patients undergoing surgical intervention, with significant variability between states and across defect type. Additional studies are needed to identify reasons for this variation and the potential impact on patient outcomes.

When should we prescribe high-dose folic acid to prevent congenital heart defects?

PURPOSE OF REVIEW: Provide a rationale for attempting prevention of congenital heart defects (CHDs). RECENT FINDINGS: Prevention of neural-tube defects can be achieved with preconceptional use of folic acid. Extrapolating results from animal studies to human pregnancy shows that folate deficiency as well as one-time exposure to environmental factors in the first 2 to 3 weeks of human gestation can result in severe CHD. Considering that approximately 50% of pregnancies are unplanned, this period of pregnancy can be considered high risk for cardiac, as well as neural, birth defects, as the woman usually is not aware of her pregnancy and may not yet be taking precautionary actions to protect the developing embryo. In mammals, folate supplementation prevents CHD induced by alcohol, by lithium, or by elevation of the metabolite homocysteine. Optimal protection of cardiogenesis was observed to occur with folate supplementation provided on the morning after conception and at higher doses than currently available in prenatal vitamin supplementation. Clinical studies show a similar pattern with high doses of folic acid required to prevent CHD. SUMMARY: Today, all patients with a family history of CHD should discuss the prenatal use of folate supplementation with their obstetricians prior to becoming pregnant.

Dynamics of pulmonary venous flow in fetuses with intrauterine growth restriction.

OBJECTIVE: To test the hypothesis that the pulmonary vein pulsatility index (PVPI) is higher in fetuses with growth restriction (IUGR) than in normal fetuses. METHODS: Twenty-two fetuses with IUGR and twenty-one (21) fetuses with appropriate growth for gestational age from healthy mothers were studied. PVPI was calculated by Doppler echocardiography [maximal velocity (systolic or diastolic peak) - pre-systolic peak / mean velocity]. Obstetric ultrasound was used to assess fetal biometry and Doppler to assess the uterine, umbilical and middle cerebral arteries PI. Statistical analysis used t test and Pearson's correlation. RESULTS: Mean gestational age was 31.5 +/- 2.1 weeks in the control group and 31.4 +/- 3.1 weeks in IUGR (P = 0.91). The PI of uterine and umbilical arteries were higher in IUGR than in controls (P < 0.001). Mean PVPI in IUGR fetuses was 1.31 +/- 0.41, and in controls it was 0.83 +/- 0.11 (P < 0.001). CONCLUSION: The pulsatility index of pulmonary venous flow in fetuses with growth restriction is higher than in normal fetuses, probably as a result of left atrial dynamics alteration secondary or not to fetal left ventricular diastolic dysfunction. © 2014 John Wiley & Sons, Ltd.

Diagnosis and treatment of fetal cardiac disease: a scientific statement from the American Heart Association.

BACKGROUND: The goal of this statement is to review available literature and to put forth a scientific statement on the current practice of fetal cardiac medicine, including the diagnosis and management of fetal cardiovascular disease. METHODS AND RESULTS: A writing group appointed by the American Heart Association reviewed the available literature pertaining to topics relevant to fetal cardiac medicine, including the diagnosis of congenital heart disease and arrhythmias, assessment of cardiac function and the cardiovascular system, and available treatment options. The American College of Cardiology/American Heart Association classification of recommendations and level of evidence for practice guidelines were applied to the current practice of fetal cardiac medicine. Recommendations relating to the specifics of fetal diagnosis, including the timing of referral for study, indications for referral, and experience suggested for performance and interpretation of studies, are presented. The components of a fetal echocardiogram are described in detail, including descriptions of the assessment of cardiac anatomy, cardiac function, and rhythm. Complementary modalities for fetal cardiac assessment are reviewed, including the use of advanced ultrasound techniques, fetal magnetic resonance imaging, and fetal magnetocardiography and electrocardiography for rhythm assessment. Models for parental counseling and a discussion of parental stress and depression assessments are reviewed. Available fetal therapies, including medical management for arrhythmias or heart failure and closed or open intervention for diseases affecting the cardiovascular system such as twin-twin transfusion syndrome, lung masses, and vascular tumors, are highlighted. Catheter-based intervention strategies to prevent the progression of disease in utero are also discussed. Recommendations for delivery planning strategies for fetuses with congenital heart disease including models based on classification of disease severity and delivery room treatment will be highlighted. Outcome assessment is reviewed to show the benefit of prenatal diagnosis and management as they affect outcome for babies with congenital heart disease. CONCLUSIONS: Fetal cardiac medicine has evolved considerably over the past 2 decades, predominantly in response to advances in imaging technology and innovations in therapies. The diagnosis of cardiac disease in the fetus is mostly made with ultrasound; however, new technologies, including 3- and 4-dimensional echocardiography, magnetic resonance imaging, and fetal electrocardiography and magnetocardiography, are available. Medical and interventional treatments for select diseases and strategies for delivery room care enable stabilization of high-risk fetuses and contribute to improved outcomes. This statement highlights what is currently known and recommended on the basis of evidence and experience in the rapidly advancing and highly specialized field of fetal cardiac care.

Evaluation of prenatal risk factors for prediction of outcome in right heart lesions: CVP score in fetal right heart defects.

OBJECTIVE: To determine the prenatal variables predicting the risk of perinatal death in congenital right heart defects. METHODS: Retrospective analysis of 28 fetuses with right heart defects was performed. Logistic regression analyses were performed to obtain odds ratios (OR) for the relationship between the risk of death and echocardiographic parameters. The parameters that correlated with the outcome were incorporated in an attempt to devise a disease-specific cardiovascular profile score. RESULTS: Fetal echocardiograms (143) from 28 patients were analyzed. The cardiovascular profile score predicted the risk of death. A lower right ventricle (RV) pressure was associated with mortality (OR 0.959; 95% confidence intervals (CI) 0.940-0.978). Higher peak aortic velocity through the aortic valve (OR 0.104; 95% CI 0.020-0.529) was associated with a better outcome. These cardiac function parameters were incorporated in a modified disease-specific CVP Score. Patients with a mean modified cardiovascular profile score of ≤ 6 were over 3.7 times more likely to die than those with scores of 7-10. CONCLUSIONS: The original Cardiovascular Profile Score predicted the risk of death in right heart defects. The modified score was not validated as a good prediction tool by this study. Fetal RV pressure estimate and peak aortic velocity can be used as independent prognostic predictors.

Effects of alcohol, lithium, and homocysteine on nonmuscle myosin-II in the mouse placenta and human trophoblasts.

OBJECTIVE: Mouse embryonic exposure to alcohol, lithium, and homocysteine results in intrauterine growth restriction (IUGR) and cardiac defects. Our present study focused on the placental effects. We analyzed the hypothesis that expression of nonmuscle myosin (NMM)-II isoforms involved in cell motility, mechanosensing, and extracellular matrix assembly are altered by the 3 factors in human trophoblast (HTR8/SVneo) cells in vitro and in the mouse placenta in vivo. STUDY DESIGN: After exposure during gastrulation to alcohol, homocysteine, or lithium, ultrasonography defined embryos exhibiting abnormal placental blood flow. RESULTS: NMM-IIA/NMM-IIB are differentially expressed in trophoblasts and in mouse placental vascular endothelial cells under pathological conditions. Misexpression of NMM-IIA/NMM-IIB in the affected placentas continued stably to midgestation but can be prevented by folate and myoinositol supplementation. CONCLUSION: It is concluded that folate and myoinositol initiated early in mouse pregnancy can restore NMM-II expression, permit normal placentation/embryogenesis, and prevent IUGR induced by alcohol, lithium, and homocysteine.

Effect of angiotensin II on the left ventricular function in a near-term fetal sheep with metabolic acidemia.

We tested the hypothesis that, in acute metabolic acidemia, the fetal left ventricle (LV) has the capacity to increase its contractility in response to angiotensin II infusion. Eleven ewes and their fetuses were instrumented at 127-138/145 days of gestation. The effect of angiotensin II on fetal LV function was assessed using intraventricular pressure catheter and tissue Doppler imaging (TDI). Angiotensin II increased fetal arterial blood pressure, whereas pH and pO(2) decreased. The heart rate and systemic venous pressure were not affected significantly. The LV end-diastolic and end-systolic pressures, as well as dP/dt(max), increased. The TDI-derived LV longitudinal myocardial isovolumic contraction velocity and its acceleration and velocity during early filling were higher than those at baseline. The incidence of absent isovolumic relaxation velocity was greater during angiotensin II infusion. In summary, during acute metabolic acidemia, the fetal left ventricle could increase its contractility in response to inotropic stimulus even in the presence of increased afterload. The diastolic LV function parameters were altered by angiotensin II.

Doppler in fetal heart failure.

Fetal echocardiography has progressed to be able to diagnose many forms of congenital heart disease (CHD) and to assess the prognosis of cardiac lesions based on their anatomy and presentation in utero. Fetal echocardiography is for pregnancies at risk of structural, functional, and rhythm-related fetal heart disease. Routine obstetrical ultrasound screening is critical in the prenatal detection of fetal heart disease/CHD. With or without CHD, fetal heart dysfunction defined as inadequate tissue perfusion may occur. Perinatal problems other than CHD can also be assessed, such as the effects of noncardiac malformations that affect hemodynamics, that is, twin-twin transfusion. Cardiac rhythm can affect cardiac function and outcome, and prenatal diagnosis can be lifesaving. A tool for the assessment of cardiac function is the Cardiovascular Profile Score that combines ultrasonic markers of fetal cardiovascular unwellness based on univariate parameters, which have been correlated with perinatal mortality. This "heart failure score" could potentially be used in much the same way as and in combination with the biophysical profile score. This study will present a summary of fetal Doppler and its place in the diagnosis and assessment of prognosis of fetal heart failure.

Ductus venosus velocimetry in acute fetal acidemia and impending fetal death in a sheep model of increased placental vascular resistance.

We investigated whether hypoxemia without acidemia affects ductus venosus (DV) blood velocity waveform pattern in sheep fetuses with intact placenta and whether worsening acidemia and impending fetal death are related to changes in DV velocimetry in fetuses with increased placental vascular resistance. A total of 34 fetuses were instrumented at 115-136/145 days of gestation. Placental embolization was performed in 22 fetuses on the fourth postoperative day, 24 h before the experiment. The control group was comprised of 12 fetuses with intact placenta. The experimental protocol consisted of fetal hypoxemia that was induced by replacing maternal inhaled oxygen with medical air. To further deteriorate fetal oxygenation and blood-gas status, uterine artery volume blood flow was reduced by maternal hypotension. Fetuses that underwent placental embolization were divided into two groups according to fetal outcome. Group 1 consisted of 12 fetuses that completed the experiment, and group 2 comprised 10 fetuses that died during the experiment. DV pulsatility index for veins (PIV) and fetal cardiac outputs (COs) were calculated. Placental volume blood flow, fetal blood pressures, and acid base and lactate values were monitored invasively. On the experimental day, the mean gestational age did not differ significantly between the groups. In groups 1 and 2, the baseline mean DV PIV and fetal COs were not statistically significantly different from the control group. In the control group, the DV PIV values increased significantly with hypoxemia. In groups 1 and 2, the DV PIV values did not change significantly, even with worsening acidemia and imminent fetal death in group 2. During the experiment, the fetal COs remained unchanged. We conclude that fetal hypoxemia increases the pulsatility of DV blood velocity waveform pattern. In fetuses with elevated placental vascular resistance, DV pulsatility does not increase further in the presence of severe and worsening fetal acidemia and impending fetal death.

Folate rescues lithium-, homocysteine- and Wnt3A-induced vertebrate cardiac anomalies.

Elevated plasma homocysteine (HCy), which results from folate (folic acid, FA) deficiency, and the mood-stabilizing drug lithium (Li) are both linked to the induction of human congenital heart and neural tube defects. We demonstrated previously that acute administration of Li to pregnant mice on embryonic day (E)6.75 induced cardiac valve defects by potentiating Wnt-beta-catenin signaling. We hypothesized that HCy may similarly induce cardiac defects during gastrulation by targeting the Wnt-beta-catenin pathway. Because dietary FA supplementation protects from neural tube defects, we sought to determine whether FA also protects the embryonic heart from Li- or HCy-induced birth defects and whether the protection occurs by impacting Wnt signaling. Maternal elevation of HCy or Li on E6.75 induced defective heart and placental function on E15.5, as identified non-invasively using echocardiography. This functional analysis of HCy-exposed mouse hearts revealed defects in tricuspid and semilunar valves, together with altered myocardial thickness. A smaller embryo and placental size was observed in the treated groups. FA supplementation ameliorates the observed developmental errors in the Li- or HCy-exposed mouse embryos and normalized heart function. Molecular analysis of gene expression within the avian cardiogenic crescent determined that Li, HCy or Wnt3A suppress Wnt-modulated Hex (also known as Hhex) and Islet-1 (also known as Isl1) expression, and that FA protects from the gene misexpression that is induced by all three factors. Furthermore, myoinositol with FA synergistically enhances the protective effect. Although the specific molecular epigenetic control mechanisms remain to be defined, it appears that Li or HCy induction and FA protection of cardiac defects involve intimate control of the canonical Wnt pathway at a crucial time preceding, and during, early heart organogenesis.

A vision for an International Society for Fetal and Perinatal Cardiovascular Disease.

PURPOSE OF REVIEW: The purpose of this review is to explain why it is now time to create an International Society for Fetal and Perinatal Cardiovascular Disease. RECENT FINDINGS: Rapid advances in four domains that involve the professionals caring for patients with congenital cardiac disease all point to the fact that it is now time to create an International Society for Fetal and Perinatal Cardiovascular Disease: fetal diagnosis - the improved ability to diagnose prenatal cardiovascular disease due to education and improved ultrasound technology; subspecialization--the development of perinatal cardiology as a true subspecialty of the professions of pediatric cardiology and perinatology; analysis of outcomes--the multidisciplinary international efforts in the areas of nomenclature and databases for the analysis of outcomes of treatments for patients with congenitally malformed hearts, efforts that span traditional geographic and subspecialty boundaries; globalization - the rapidly evolving global organization of professionals caring for patients with congenital heart disease. SUMMARY: Healthcare professionals caring for the pregnant woman and fetus with congenital cardiac disease would be enthusiastic about the creation of an International Society for Fetal and Perinatal Cardiovascular Disease in order to achieve multiple objectives: to discuss the management of prenatal and perinatal cardiovascular disease (not exclusively cardiac malformations); to benefit from educational programs covering prenatal and perinatal physiology and pathophysiology, clinical and technical topics, as well as genetic, ethical, and psychosocial aspects of this relatively new discipline; and finally to share our basic science, translational, and clinical research interests.

Molecular effects of lithium exposure during mouse and chick gastrulation and subsequent valve dysmorphogenesis.

BACKGROUND: Lithium (Li) has been associated with cardiac teratogenicity in the developing fetus. We took advantage of the association of therapeutic administration of Li with an increase in heart defects to gain insight into both normal and pathological heart and valve development with GSK-3 inhibition. The objective of this study was to define whether Li mimicry of canonical Wnt/beta-catenin signaling induces cardiac valve defects. METHODS: Li was administered by a single intraperitoneal injection to the pregnant mouse on embryonic day E6.75, much earlier than heretofore analyzed. On E15.5 developing heart defects were defined by Doppler ultrasound. The embryonic hearts were analyzed for changes in patterning of active canonical Wnt expression and nuclear factor of the activated T cells-c1 (NFATc1), both key regulators of valve development. Li-exposed chick embryos were used to define the early cell populations during gastrulation that are susceptible to GSK-3 inhibition and may relate to valve formation. RESULTS: Li exposure during gastrulation decreased the number of prechordal plate (PP) cells that reached the anterior intestinal portal, a region associated with valve development. Li decreased expression of Hex, an endoderm cardiac inducing molecule, normally also expressed by the PP cells, and of Sox 4 at the anterior intestinal portal and NFAT, critical factors in valvulogenesis. CONCLUSIONS: Cells existing already during gastrulation are associated with valve formation days later. The Wnt/beta-catenin signaling in PP cells is normally repressed by Wnt antagonists and Hex is up-regulated. The antagonism occurring at the receptor level is bypassed by Li exposure by its intracellular inactivation of GSK-3 directly to augment Wnt signaling.

Controversies of fetal cardiac intervention.

Remarkable advances in ultrasound imaging technology have made it possible to diagnose fetal cardiovascular lesions as early as 12-14 weeks of gestation and to assess their physiological relevance by echocardiography. Moreover, invasive techniques have been developed and refined to relieve significant congenital heart disease (CHD), such as critical aortic and pulmonary stenoses in the pediatric population including neonates. Recognition of the fact that certain CHDs can evolve in utero, and early intervention may improve the outcome by altering the natural history of such conditions has led to the evolution of a new fetal therapy, i.e. fetal cardiac intervention. Two entities, pulmonary valvar atresia and intact ventricular septum (PA/IVS) and hypoplastic left heart syndrome (HLHS), are associated with significant morbidity and mortality even with postnatal surgical therapy. These cases are believed to occur due to restricted blood flow, leading to impaired growth and function of the right or left ventricle. Therefore, several centers started the approach of antenatal intervention with the primary goal of improving the blood flow through the stenotic/atretic valve orifices to allow growth of cardiac structures. Even though centers with a reasonable number of cases seem to have improved the technique and the immediate outcome of fetal interventions, the field is challenged by ethical issues as the intervention puts both the mother and the fetus at risk. Moreover, the perceived benefits of prenatal treatment have to be weighed against steadily improving postnatal surgical and hybrid procedures, which have been shown to reduce morbidity and mortality for these complex heart defects. This review is an attempt to provide a balanced opinion and an update on fetal cardiac intervention.

Electrophysiological characteristics of fetal atrioventricular block.

OBJECTIVES: The purpose of our work was to define the complex electrophysiological characteristics seen in second- (2 degrees) and third-degree (3 degrees) atrioventricular block (AVB) and to longitudinally follow the development of atrial and ventricular heart rate and rhythm patterns with a goal of identifying heart rate and rhythm patterns associated with urgent delivery or neonatal pacing. BACKGROUND: The electrophysiological characteristics of congenital AVB before birth have not been extensively studied, yet the mortality from this disease is substantial. Along with advances in fetal therapies and interventions, a comprehensive natural history specific to the etiology of AVB, as well as the electrophysiological factors influencing outcome, are needed to best select treatment options. METHODS: Twenty-eight fetuses with AVB were evaluated by fetal magnetocardiography; 21 fetuses were evaluated serially. RESULTS: Fetuses with 2 degrees AVB and isolated 3 degrees AVB showed: 1) diverse atrial rhythms and mechanisms of atrioventricular conduction during 2 degrees AVB; 2) junctional ectopic tachycardia and ventricular tachycardia during 3 degrees AVB; 3) reactive ventricular and atrial fetal heart rate (FHR) tracings at ventricular rates >56 beats/min; and 4) flat ventricular FHR tracings at ventricular rates <56 beats/min despite reactive atrial FHR tracings. In contrast, fetuses with 3 degrees AVB associated with structural cardiac disease exhibited predominantly nonreactive heart rate tracings and simpler rhythms. CONCLUSIONS: Second-degree AVB, isolated 3 degrees AVB, and 3 degrees AVB associated with structural cardiac disease manifest distinctly different electrophysiological characteristics and outcome. Fetuses with 2 degrees AVB or isolated 3 degrees AVB commonly exhibited complex, changing heart rate and rhythm patterns; all 19 delivered fetuses are alive and healthy. Fetuses with structural cardiac disease and 3 degrees AVB exhibited largely monotonous heart rate and rhythm patterns and poor prognosis. Junctional ectopic tachycardia and/or ventricular tachycardia may be characteristic of an acute stage of heart block.

Metabolic acidosis decreases fetal myocardial isovolumic velocities in a chronic sheep model of increased placental vascular resistance.

We hypothesized that acute fetal metabolic acidosis decreases fetal myocardial motion in a chronic sheep model of increased placental vascular resistance (R(ua)). Eleven ewes and fetuses were instrumented at 118-122 days of gestation. After 5 days of recovery and 24 h of placental embolization to increase R(ua), longitudinal myocardial velocities of the right and left ventricles and interventricular septum (IVS) were assessed at the level of the atrioventricular valve annuli via tissue Doppler imaging (TDI). Ventricular inflow (E and A waves) and outflow velocities were obtained, and cardiac outputs were calculated. All measurements were performed at baseline and during fetal acidosis caused by epidural anesthesia-induced maternal hypotension, which decreased uterine artery volume blood flow, fetal oxygenation, arterial pH, and base excess and increased lactate. Compared with baseline, the peak isovolumic myocardial contraction and relaxation velocities of the ventricles and IVS, early relaxation velocity (E') of the ventricles, and systolic velocity of the IVS decreased during metabolic acidosis. The proportion of isovolumic contraction time of the cardiac cycle increased but the isovolumic relaxation and ejection time proportions and the TDI Tei index did not change. The E-to-E' ratio for both ventricles was higher during metabolic acidosis than at baseline. During metabolic acidosis, right and left ventricular cardiac outputs remained unchanged compared with baseline. In sheep fetuses with increased R(ua) and acute metabolic acidosis, global cardiac function was preserved. However, acute metabolic acidosis impaired myocardial contractility during the isovolumic phase and relaxation during the isovolumic and early filling phases of the cardiac cycle.

Functional assessment of the evolution of congenital heart disease in utero.

PURPOSE OF REVIEW: This article reviews recent developments in the assessment of changes in structure and function in the fetal heart with the focus on congenital heart disease malformations. RECENT FINDINGS: Use of the combination of the cardiovascular profile score, the biophysical profile score and additional physiological measurements with Doppler echocardiography have allowed better characterization of disease states and the changes that can occur in utero during the last two trimesters of gestation. SUMMARY: A comprehensive examination of the structure and function of the fetal heart together with the evaluation of other parameters of fetal wellbeing are necessary for comprehensive assessment of the evolution of congenital heart disease in utero. Only such an objective surveillance can elucidate the pathophysiology and natural history, guide appropriate timing of intervention, monitor the success of any in-utero therapy, and predict perinatal outcome.