Predicting High-Risk Fetal Cardiac Disease Anticipated to Need Immediate Postnatal Stabilization and Intervention with Planned Pediatric Cardiac Operating Room Delivery

BACKGROUND

Distances between delivery and cardiac services can make the care of fetuses with cardiac disease at risk of acute cardiorespiratory instability at birth a challenge. In 2013 we implemented a fetal echocardiography-based algorithm targeting fetuses considered high risk for acute cardiorespiratory instability at ≤2 hours of birth for delivery in our pediatric cardiac operating room of our children's hospital, and, herein, examine our experience.

METHODS AND RESULTS

We reviewed maternal and postnatal medical records of all fetuses with cardiac disease encountered January 2013 to March 2022 considered high risk for acute cardiorespiratory instability. Secondary analysis was performed including all fetuses with diagnoses of d-transposition of the great arteries/intact ventricular septum (d-TGA/IVS) and hypoplastic left heart syndrome (HLHS) encountered over the study period. Forty fetuses were considered high risk for acute cardiorespiratory instability: 15 with d-TGA/IVS and 7 with HLHS with restrictive atrial septum, 4 with absent pulmonary valve syndrome, 3 with obstructed anomalous pulmonary veins, 2 with severe Ebstein anomaly, 2 with thoracic/intracardiac tumors, and 7 others. Pediatric cardiac operating room delivery occurred for 33 but not for 7 (5 with d-TGA/IVS, 2 with HLHS with restrictive atrial septum). For high-risk cases, fetal echocardiography had a positive predictive value of 50% for intervention/extracorporeal membrane oxygenation/death at ≤2 hours and 70% at ≤24 hours. Of "low-risk" cases, 6/46 with d-TGA/IVS and 0/45 with HLHS required intervention at ≤2 hours. Fetal echocardiography for predicting intervention/extracorporeal membrane oxygenation/death at ≤2 hours had a sensitivity of 67%, specificity 93%, and positive and negative predictive values of 80% and 87%, respectively, for d-TGA/IVS, and 100%, 95%, 71%, and 100% for HLHS, respectively.

CONCLUSIONS

Fetal echocardiography can predict the need for urgent intervention in a majority with d-TGA/IVS and HLHS and in half of the entire spectrum of high-risk cardiac disease.

3D/4D spatiotemporal image correlation (STIC) fetal echocardiography provides incremental benefit over 2D fetal echocardiography in predicting postnatal surgical approach in double-outlet right ventricle

OBJECTIVE

To analyze the incremental benefit of 3D/4D spatiotemporal image correlation (STIC) fetal echocardiography over 2D fetal echocardiography with respect to the accuracy of identification of anatomic details crucial for surgical decision-making and in predicting surgical approach in fetuses with double-outlet right ventricle (DORV).

METHODS

This was a retrospective study of fetuses with DORV which had undergone both 2D echocardiography and 3D/4D STIC echocardiography and which underwent surgery postnatally in a tertiary pediatric cardiac center in Kerala between October 2015 and March 2019. All such cases with normal atrial arrangement, concordant atrioventricular connections and balanced ventricles were included. 2D and 3D/4D STIC fetal echocardiographic data were analyzed by two experienced observers blinded to the other dataset. Anatomic variables crucial for surgical decision-making, i.e. location and routability of the ventricular septal defect, relationship of the great arteries and presence of outflow obstruction, were compared between the two modalities with respect to agreement with postnatal echocardiography. The accuracy of prenatal prediction of the surgical pathway was compared between 2D and 3D/4D modalities with respect to the procedure undertaken.

RESULTS

Included in the study were 22 fetuses with DORV which had undergone both 2D and 3D/4D imaging as well as postnatal surgery. Accuracy of prenatal interpretation of all four anatomic variables was significantly higher using 3D/4D STIC than using 2D fetal echocardiography (19/22 (86.4%) vs 8/22 (36.4%), P < 0.001). Surgical procedures included single-stage repair in 14 (63.5%) patients and a multistage approach in eight (36.4%). Prenatal prediction of the surgical pathway was significantly more accurate on 3D/4D STIC than on 2D echocardiography (20/22 (90.9%) vs 12/22 (54.5%), P = 0.021). Prenatal predictive accuracy of single-stage biventricular repair was significantly better for 3D/4D STIC than for 2D echocardiography (14/14 (100%) vs 8/14 (57.1%), P = 0.04).

CONCLUSION

Addition of 3D/4D STIC to conventional 2D fetal echocardiography confers incremental benefit on the accuracy of identification of anatomic details crucial for surgical decision-making and the prediction of postnatal surgical approach in fetuses with DORV, thereby potentially aiding prenatal counseling. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Tissue Doppler imaging in fetuses with aortic stenosis and evolving hypoplastic left heart syndrome before and after fetal aortic valvuloplasty

OBJECTIVES

Fetal aortic valvuloplasty can improve filling and reduce afterload of the left ventricle in critical aortic stenosis. Success of an intrauterine intervention is currently measured by technical success, clinical survival and eventual postnatal biventricular physiology. In the present study we investigated the use of tissue Doppler imaging (TDI) to evaluate changes in ventricular function assessed before and after prenatal aortic valvuloplasty.

METHODS

Between October 2008 and December 2012, cardiac function was assessed by TDI before and after intervention in 23 fetuses that underwent technically successful valvuloplasty for critical aortic stenosis and in which postnatal outcome was known. The measurements were transformed into gestational age-independent Z-scores where appropriate.

RESULTS

Mean ± SD gestational age at intervention was 27.5 ± 3.1 weeks. Of the 23 fetuses, 14 had biventricular outcome. Before intervention all left ventricular (LV) TDI-derived parameters and mitral annular plane systolic excursion (MAPSE) were severely abnormal. It was possible to demonstrate considerably improved cardiac function after technically successful valvuloplasty. Among fetuses with postnatal biventricular outcome, TDI-derived LV myocardial peak velocity during early diastole (E') and myocardial peak velocity during systole in the ejection phase (S') significantly increased, E'/myocardial peak velocity during late diastole with atrial contraction (A') increased towards normal values, and LV transmitral-to-mitral-annular diastolic velocity ratio (E/E') and myocardial performance index (MPI') decreased but remained abnormally elevated. In addition, right ventricular A', S' and MPI' significantly improved after intervention.

CONCLUSION

Technically successful fetal aortic valvuloplasty led to significantly improved myocardial performance. It was possible to use TDI to detect distinct changes in ventricular function and TDI-derived parameters correlated with a biventricular outcome after birth. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Twin Reversed Arterial Perfusion (TRAP) Sequence: A Case Report and Review of Treatment

A cardiac twin or twin reversed arterial perfusion (TRAP) sequence is a rare unique complication of monozygotic multiple pregnancy. In this disorder, there is a normally formed donor (the pump twin) who has features of congestive heart failure (CHF) as well as a recipient (the acardiac twin) who lacks a well-defined a heart structure. Also evident are other structures, namely the TRAP sequencefrom pump to acardiacfetus via single artery-to-artery and vein-to-vein anastomoses directly between the two cords or indirectly on the chorionic plate. Overall, the perinatal mortality rate for the pump twin is 35-55%. Prenatal diagnosis and prognosis factors can be examined through ultrasound. The optimal management of a cardiac twin pregnancies is controversial. The expected treatment of acardiac anomaly presently relies on maximizing the chance ofterm delivery and preventing CHF in the healthy pump twin or interrupting vascularization between the two twins. This article reported the experience of acardiac twin management in Thammasat University Hospital and reviewed the current knowledge ofthe condition, prenatal diagnosis, prognosis factor and management options focusing on conservative management compared to invasive treatment.

[In-utero treatment of hypoplastic left heart syndrome]

In-utero treatment of fetal aortic stenosis (AS) may prevent hypoplastic left heart syndrome. A girl was diagnosed prenatally with severe AS and was referred to the Women's and Children's Hospital in Linz, Austria, where she underwent an intrauterine valvuloplasty of the aortic valve. Postnatally, the girl was given prostaglandin and operated a.m. Ross-Konno. An echocardiography at the age of four months showed a neoaorta without stenosis and insufficiency and a normal systolic function of the left ventricle. This treatment must be carefully considered when dealing with fetuses with AS.

Fetal cardiac interventions: rationale, risk and benefit

Fetal congenital heart disease may progress during pregnancy and may lead to irreversible myocardial or pulmonary damage. The rationale of fetal intracardiac interventions is to change fetal hemodynamics, prevent secondary damage and improve long-term outcome at an acceptable risk for mother and fetus. This review focuses on the current experience about patient selection, risks and benefits of this technique.

[The first successful fetal aortic balloon valvuloplasty in Poland]

Prenatal aortic valvuloplasty is performed only in few perinatal centers in the world. Critical aortic stenosis which can lead to hypoplastic left heart syndrome or severe fetal heart failure with nonimmune hydrops is an indication for this procedure. Prenatal intervention can change the natural course of the disease. Authors present the first successful fetal balloon aortic valvuloplasty in Poland. It was performed in a 29-week fetus with critical aortic stenosis, severe impairment of left ventricular function, heart failure and fetal hydrops. After successful intervention, without any complications, left ventricular function and fetal condition improved gradually Effective fetal intervention was possible after few months of preparation and building a team of specialists. This is the first successful fetal cardiac intervention in Poland, which opens the way to the new era of fetal cardiology and hopefully will lead to improve results in children with this critical heart defect.

Impact of fetal cardiac intervention on congenital heart surgery

Fetal cardiac interventions performed by interventional cardiologists are currently in a clinical experimental phase. The 3 most frequent interventions are: 1) aortic balloon valvuloplasty for critical aortic stenosis with a small left ventricle or with a normal size left ventricle but poor function; 2) atrial septostomy for highly restrictive or intact atrial septum in hypoplastic left heart syndrome; and 3) pulmonary valvuloplasty for pulmonary atresia and hypoplastic right ventricle. Current impact on everyday congenital heart surgery practice is small, but may increase in the future.

Evaluation of the CHOP cardiovascular score as a prognostic predictor of outcome in twin-twin transfusion syndrome after laser coagulation of placental vessels in a prospective cohort

OBJECTIVE

To investigate the prognostic value of cardiac function assessment by the previously reported CHOP (Children's Hospital of Philadelphia) cardiovascular score in twin-twin transfusion syndrome (TTTS).

METHODS

All consecutive monochorionic pregnancies presenting with TTTS over a 24-month period were evaluated by preoperative echocardiography before percutaneous laser coagulation of chorionic vessels. Each of the 12 items of the CHOP score was evaluated prospectively and the cardiovascular score was categorized into stages using previously published cut-offs. The outcome considered for this study was neonatal survival of neither, one or both twins.

RESULTS

In total, 215 pregnancies were enrolled. Due to technical issues, CHOP evaluation was incomplete in 16% of cases and follow-up was unavailable in 12%. Overall, there was a significant relationship between the CHOP score and the Quintero staging system, although this relationship was significantly reduced when parameters used in the Quintero system were removed from the CHOP score. Based upon neonatal survival, the CHOP score did not show any prognostic value regarding overall pregnancy outcome or individual recipient survival.

CONCLUSION

Cardiac function assessment using the CHOP score is not of clinical use as a prognostic marker in TTTS. This suggests that cardiac function may not be of interest for preoperative staging when laser coagulation is the first-line treatment, other than to confirm the diagnosis of TTTS requiring surgery.

Profiling fetal cardiac function in twin-twin transfusion syndrome

OBJECTIVES

Cardiomyopathy in the recipient twin is a marker of severity in twin-twin transfusion syndrome (TTTS), making it a potentially valuable tool for staging the disease. This study aimed to provide a quantitative description of cardiac function in the recipient twin.

METHODS

Consecutive monochorionic pregnancies complicated with TTTS and treated by percutaneous laser coagulation underwent fetal echocardiography before surgery. An unsupervised classification analysis was conducted to identify groups of twins with similar cardiac profiles. The predictive value of the recipient twin's preoperative cardiac function based on these profiles was assessed, using perinatal death of at least one twin as the main outcome. The cardiac function profiles that we identified were compared with the current Quintero staging.

RESULTS

A total of 107 pregnancies were included, with six of these lost to follow-up; 63/107 complete cases were available for multivariate description of the recipient's cardiac function. Three different preoperative cardiac profiles were identified with increasing right and left myocardial performance index, decreasing right and left shortening fraction, and increasing ductus venosus pulsatility index. Although the three groups represented progressive stages of the syndrome-related cardiomyopathy, no correlation was found with pregnancy outcome. Of Quintero Stage 1 cases, 55% showed significant alterations of cardiac function in the recipient twin.

CONCLUSIONS

Progressive cardiomyopathy can be assessed quantitatively in the recipient twin and does not influence pregnancy outcome when fetoscopic laser coagulation is the first-line treatment. Compared with the current staging, cardiac profiling allows discrimination of cases with significant myocardial dysfunction.

Cerebral blood flow characteristics and biometry in fetuses undergoing prenatal intervention for aortic stenosis with evolving hypoplastic left heart syndrome

Children with hypoplastic left heart syndrome (HLHS) are at risk for neurodevelopmental dysfunction; prenatal factors may play a role in this predilection. Cerebral blood flow profiles are abnormal in fetuses with HLHS, raising the possibility that cerebral hemodynamics in utero may be related to neurodevelopmental abnormalities. Prenatal aortic valvuloplasty for fetal aortic stenosis with evolving HLHS is technically feasible and improves left heart hemodynamics. This study aimed to assess the effects of prenatal intervention on cerebral blood flow profiles and head circumference in fetuses with evolving HLHS. Seventy fetuses underwent prenatal aortic valvuloplasty for evolving HLHS (median 23 weeks gestation). Among 46 fetuses that had successful valvuloplasty and available data, middle cerebral artery (MCA) pulsatility (PI) and resistive (RI) indices were abnormal (Z-scores -1.7+/-1.1 and -2.2+/-1.4, p<0.001). Early post-valvuloplasty (n=33) and at late gestation follow-up (n=28), MCA PI and RI Z-scores remained low with no difference from pre- or early postintervention. Fetal head circumference was normal, as were umbilical artery PI and RI Z-scores. Cerebral blood flow characteristics are abnormal in mid-gestation fetuses with evolving HLHS, suggesting low cerebral vascular impedance. The mechanisms and significance of these abnormalities are unknown. Prenatal aortic valvuloplasty did not have a major impact on these indices. (E-mail: doff.mcelhinney@cardio.chboston.org).

[Anesthetic management during cardiac bypass in fetal lambs]

OBJECTIVE

To summarize the anesthetic management in fetal lamb cardiac bypass.

METHODS

Five ewes at 120-140 days of gestation were anesthetized intramuscularly with katamine hydrochloride, intubated and ventilated with a respirator. Anesthesia was maintained with fentanyl and vecuronium. Lactated Ringer's solution and magnesium sulfate were infused to maintain the mean blood pressure (MAP) over 70 mmHg and uterine relaxation. The fetal lambs received anesthesia with fentanyl and vecuronium intramuscularly via the uterine wall. Fetal cardiac bypass was established with pulmonary artery and right atrium cannulation, lasting for 30 min. The hemodynamic and blood gas data of the ewes and fetal lambs were recorded before bypass, at 30 min during bypass, and at 1 and 2 h after cessation of bypass. The pulse index of the umbilical artery (PIua) and the ewe's uterine artery (PIeu) were monitored simultaneously.

RESULTS

The MAP and heart rate (HR) of the fetus remained normal during the anesthesia. PIua increased significantly after cessation of bypass (P<0.05). Although the fetal oxygen tension in the axillary artery remained normal, the fetal lambs showed hypercarbia and acidosis after cessation of bypass (P<0.05). The maternal MAP and HR remained normal. The PIeu decreased significantly during bypass (P<0.05) and recovered the normal level after cessation of bypass. The arterial blood gas of the ewes was normal during the experiment.

CONCLUSION

Maintaining high hemodynamics in the ewes, application of uterine relaxation and intensive care during anesthesia are crucial in anesthetic management of cardiac bypass in fetal lambs.

Twin-reversed arterial perfusion sequence: pre- and postoperative cardiovascular findings in the 'pump' twin

OBJECTIVES

To assess cardiovascular findings in twin-reversed arterial perfusion (TRAP) sequence pre- and post-therapy and compare these findings to traditional obstetric markers, defined as acardius to pump twin weight ratio and presence of polyhydramnios.

METHODS

This was a retrospective review of 27 cases of TRAP sequence diagnosed between 2004 and 2008. Echocardiographic data included indexed cardiac output and functional and anatomic parameters. Ultrasound reports were reviewed for acardius to pump twin weight ratio and polyhydramnios. We assessed the relationship between cardiac output and the remaining cardiac/obstetric variables obtained pre- and post-treatment.

RESULTS

Twenty-three subjects had complete echocardiographic data sets at initial evaluation (mean gestational age, 20.4 +/- 2.5 weeks) and, of these, post-treatment echocardiographic evaluation was available in 10. Six of seven (86%) pump twins with elevated indexed cardiac output had significant cardiovascular compromise. Most fetuses with abnormal cardiac output or right ventricular dysfunction normalized post-therapy. There was no relationship between cardiac output and obstetric markers.

CONCLUSIONS

Elevated indexed cardiac output is strongly associated with cardiovascular compromise. Traditional obstetric prognosticators do not correlate with cardiovascular derangements. In pump twins with cardiac compromise, postoperative cardiovascular status improves acutely. Given this analysis, we conclude that assessment of cardiovascular findings should be incorporated into the management and treatment of TRAP sequence.

[The research of animal model setting-up in human intra-utero fetal cardiac intervention]

OBJECTIVE

To research the techniques and correlated issues during analogous procedure of human intro-utero fetal cardiac intervention in animal model, so as to impulse the clinical utilizing of cardiac intervention in human fetus with severe cardiovascular malformations.

METHODS

Eight bigeminal pregnant ewes in latter 2nd-trimester and 3rd- trimester were taken into the research of fetal cardiac intervention. Under continuous ultrasound guidance, advanced an cannula and stylet needle through the maternal abdomen, uterine wall, and fetal lamb chest wall and into the fetal LV, then imitate human balloon aortic valvuloplasty at valve ring level. Probed into aspects of animal preparation, position of fetal lambs, paracentesis point selecting, main points of intervention, ultrasound utilizing, fetal lambs incubation and protection to placenta as well as umbilical cord.

RESULTS

Eight pregnant ewes were all survival after procedure, 2 was executed after fetus' death, the other 6 continued gestation until spontaneous vaginal delivery after an uneventful pregnancy. After parturition the 6 ewes were in good condition. There were no nick infection, chorioamnionitis and other complications. Eight/sixteen fetal lambs were undergone intro-utero cardiac intervention. The values of body weight and Hct of lambs which were executed, pre-term and full-term delived were (1.77 +/- 0.14) kg vs. (2.15 +/- 0.23) kg vs. (2.41 +/- 0.19) kg and 29%o-33% vs. 27%-35% vs. 37%-41%. In autopsy, hydropericardium was found in 4/8 with 1-2.5 mL and 1/8 with 5 mL. Besides 1/8 with interventricular septum centesis injury, there was no centesis damage to endocardium, valve, chordae tendineae, papillary muscles and sortic tunics intima. Whereas there was no centesis injury to lung, liver and chylostomach, no trace of ericardium and thoracic infection.

CONCLUSIONS

Animal model of intra-utero fetal cardiac intervention was setted up successfully, the experiences in this study was worth to be payed attention to in human fetal cardiac intervention.

The chick embryo as a model for intrauterine ultrasound-guided heart intervention

OBJECTIVES

Prenatal minimally invasive therapy represents a challenging option for reducing long-term complications of pathological fetal heart development. Here, the potential of the chick embryo as a model for ultrasound-guided intrauterine cardiac intervention is explored.

METHODS

Chick embryos were incubated for 18 days in fenestrated eggs and their hearts were punctured in ovo under ultrasound guidance. Indian ink and Nile blue sulfate were applied to mark the injection channel. After cardiac intervention, embryos were further incubated and subsequently sacrificed for macroscopic and histological evaluation of the heart.

RESULTS

Stereomicroscopic analysis revealed that the catheter had successfully penetrated the cardiac ventricular wall in 26/38 embryos. The myocardium was not severely injured. Histological evaluation showed that the myocardium had almost reoccluded after the intervention and that the injection channel was clogged with fibrin. In one case, the embryo was not sacrificed, but was removed from the egg 24 h after the intervention, with no signs of cardiac dysfunction, and was followed up for 6 months.

CONCLUSIONS

Intrauterine ultrasound-guided heart intervention in the human fetus can be simulated in the chick embryo. Fenestrated eggs have to be used because the egg shell and shell membrane are impermeable to ultrasound.

Fetal intervention for cardiac disease: the cutting edge of perinatal care

Fetal cardiac valvuloplasty has been proposed for progressive cardiac disease with a poor prognosis, such as critical aortic stenosis and pulmonary atresia with intact ventricular septum and balloon atrial septostomy for hypoplastic left heart syndrome, or simple transposition of the great arteries with closed or restrictive inter-atrial communication. It is anticipated that early rescue of ventricles or the pulmonary veins from an unfavourable environment may promote healthier ventricular and vascular growth and improve postnatal outcomes. While close collaboration between the fetal medicine specialist and perinatal cardiologist may optimize the chances of technical success, obstacles to progress include the relative rarity of suitable cases and late referral for therapy. In common with other interventions in fetal medicine, there is a learning curve, and it would benefit progress if the procedures were initially concentrated in just a few centres to enable them to develop skills and experience. Following careful evaluation, it may then be desirable to train further centres and roll out best practice models.

In-utero intervention for severe congenital heart disease

The concept of fetal therapy is well established for many disorders diagnosed before birth but practical issues regarding its introduction into clinical practice are more difficult. Cardiac malformations are common, with major lesions affecting about 3.5 per thousand pregnancies; however, only a small proportion of these is likely to benefit from an intrauterine intervention. In addition, there are no good animal models of human cardiac disease and our knowledge of the underlying mechanisms is at best sketchy. This combination of factors has resulted in slow progress in developing effective therapies for the intrauterine management of cardiac disease. Recent research and clinical developments have included percutaneous valvuloplasty for severe aortic and pulmonary stenosis, perforation of the closed or restrictive inter-atrial septum and pacing for complete heart block. Progress in these endeavours has been variable but - overall - shows promise for treatment of the human fetus.

Increased Ventricular Preload Is Compensated by Myocyte Proliferation in Normal and Hypoplastic Fetal Chick Left Ventricle

Hemodynamics influence cardiac development, and alterations in blood flow may lead to impaired cardiac growth and malformations. The developing myocardium adapts to augmented workload by increasing cell number (hyperplasia). The aim of this study was to determine the influence of alterations in ventricular preload on fetal myocyte proliferation by manipulation of intracardiac shunting at the atrial level. We hypothesized that partial clipping of the right atrial appendage would increase the blood flow to the left ventricle and, in turn, lead to an increase in chamber volume and myocardial mass based on myocyte proliferation. Using an ex ovo culture setup, we performed partial right atrial clipping on embryonic day 8 chick embryos. Ultrasound imaging was performed before and after the surgery to assess the changes in left ventricular volume. Sampling after 24 hours was preceded by 2 hour of pulse-labeling with 5-bromodeoxyuridine. Ultrasound imaging showed that partial right atrial clipping led to a significant increase in left ventricular end-diastolic volume, demonstrating increased blood flow and preload. Anti–5-bromodeoxyuridine immunolabeling revealed a significant increase in myocyte proliferation in the left ventricle and atrium. No significant changes were found in the right heart structures. Increased left ventricular myocyte proliferation and myocardial mass after right atrial clipping was also observed in embryos with experimental left ventricular hypoplasia. These results demonstrate the ability of fetal myocardium to respond to increased preload by myocyte hyperplasia and support the rationale for prenatal surgical interventions in certain cases of congenital heart disease such as hypoplastic left heart syndrome.

Current treatments for congenital aortic stenosis

PURPOSE OF REVIEW

Congenital valvar aortic stenosis is a challenging disease that often requires repeated palliative procedures. Stenosis can range from mild and asymptomatic, not requiring intervention, to severe, as seen in hypoplastic left heart syndrome. New advances such as fetal balloon valvuloplasty, improvements in the Ross technique, and long-term studies of trans-catheter balloon valvuloplasty and surgical valvotomy warrant a review of the outcomes and optimal timing of the various interventions.

RECENT FINDINGS

Fetal balloon valvuloplasty has shown promise. Despite some mortality and morbidity, some fetuses are showing significant growth in left ventricular structures, allowing biventricular repair. In neonates and infants with congenital aortic stenosis, excellent initial results are obtained with trans-catheter balloon valvuloplasty, although stenosis resistant to further balloon dilation or regurgitation may develop, necessitating surgical intervention. Midterm results from the Ross procedure are encouraging, demonstrating low rates of mortality, aortic insufficiency and re-intervention. Stenosis of the pulmonary allograft may be inevitable, and recent long-term follow-up suggests an increase in aortic insufficiency.

SUMMARY

While availability of fetal balloon valvuloplasty is limited, it has promise for promoting in-utero left ventricle growth and improving function. The optimal procedure for infants and neonates is trans-catheter balloon valvuloplasty. For older patients, the Ross procedure is the repair of choice, although more long-term studies are needed to assess the natural course of the autograft. Outcomes should improve with advances in pulmonary allografts.

Fetal transesophageal echocardiography: clinical introduction as a monitoring tool during cardiac intervention in a human fetus

Because of insufficient imaging by maternal transabdominal fetal echocardiography (TAE) in a human fetus with aortic atresia, imperforate atrial septum and progressive cardiac failure, we assessed the feasibility of fetal transesophageal echocardiography (TEE) as a monitoring tool during fetal cardiac intervention at 24 + 6 weeks of gestation. Percutaneous fetoscopic intraesophageal deployment of the ultrasound catheter was achieved and did not result in any maternal or fetal complications. Fetal TEE permitted substantially clearer definition of fetal cardiac anatomy and intracardiac device manipulations than conventional maternal TAE. Despite the employment of various devices, no sufficiently large opening could be achieved within the atrial septum. Although the fetus tolerated the procedure remarkably well and satisfactory fetoplacental flow could be documented at the end of the procedure, the fetus died from progressive cardiac failure 3 days after the intervention. Fetoscopic TEE is feasible in the human fetus and permits substantially clearer definition of fetal cardiac anatomy and intracardiac manipulations than conventional maternal TAE. Based on the observation of spontaneous closure of multiple iatrogenic perforations of the atrial septum, specialized devices are required in order to improve the technical success rate of septoplasty methods and hence the survival odds of these high-risk patients.

Pediatric catheter interventions: a year in review 2004-2005

PURPOSE OF THE REVIEW

The fields of pediatric and congenital cardiac interventions continue to expand at a rapid pace. The last few years have witnessed a tremendous explosion in procedures such as the transcatheter closure of secundum atrial septal defects, patent foramen ovale, patent ductus arteriosus, stent placement for pulmonary artery stenosis, and coarctation of the aorta. The purpose of this review is to highlight important publications in the last year and the direction the field is taking.

RECENT FINDINGS

Research data over the last year has concentrated on six main themes: (a) mid-to-long-term data for device closure of atrial septal defects, the incidence of late cardiac erosions, thrombus formation and heart block; (b) the transcatheter closure of muscular ventricular septal defects; (c) the transcatheter closure of perimembranous ventricular septal defects; (d) the placement of bioprosthetic valves in the pulmonary and aortic positions; (e) the 'hybrid' approach that combines surgical and interventional techniques in the management of various congenital cardiac defects; and (f) fetal interventions.

SUMMARY

This review outlines the key data presented in the literature involving interventional cardiology for pediatric and congenital cardiac defects over the last year. It illustrates that in close collaboration with industry, together with bioengineers and cardiothoracic surgeons, adult cardiac interventionists and perinatologists should continue to expand the role of pediatric catheter interventions. Fetal interventions have the potential to alter the natural history of abnormal cardiac development.

Preliminary results of fetal cardiac bypass in nonhuman primates

OBJECTIVE

Fetal cardiac surgery has potential benefits for treatment of some congenital heart defects. However, placental dysfunction as a result of fetal bypass, fetal stress, and fetal exposure to external milieu needs to be overcome to optimize the outcomes of fetal cardiac bypass. In this study we evaluated the technical feasibility of cardiac bypass in the nonhuman primate fetus and the efficacy of different anesthetic approaches.

METHODS

Twelve baboon fetuses, average gestation 146 +/- 8 days and weight 696 +/- 184 g, were used. Three fetuses were excluded from the study because of nuchal cord presentations. The animals were separated into two anesthesia groups: isoflurane (n = 6) and fentanyl and midazolam (n = 3). A miniature roller pump circuit without oxygenator was used for fetal bypass for 30 minutes. No blood transfusion was performed. Fetal blood gas samples were collected before bypass, during bypass, and at 15 and 60 minutes after bypass.

RESULTS

All fetuses in the isoflurane group were successfully placed on the cardiac bypass circuit. However, 2 animals in the fentanyl and midazolam group were not placed on the bypass circuit because of sustained elevation in maternal uterine tone. All maternal baboons survived. Of the 6 fetuses in the isoflurane group, 5 survived for 60 minutes; however, placental function continued to deteriorate after bypass (Pa o 2 33 +/- 3 mm Hg before bypass, 23 +/- 6 mm Hg 15 minutes after, and 18 +/- 9 mm Hg 60 minutes after).

CONCLUSION

The technical feasibility of cardiac bypass in nonhuman primate fetuses weighing less than 1000 g was confirmed. Isoflurane anesthesia appears to be superior to fentanyl and midazolam anesthesia for fetal cardiac surgery because of adequate uterine relaxation.

Fetal interventions for cardiac defects

This article focuses on the current status of in utero catheter interventions for congenital heart disease. The discussion of fetal interventions for cardiac defects briefly reviews the evolution of approaches to congenital heart disease and issues surrounding the prenatal detection of cardiac defects, the rationale for fetal intervention, and optional candidates for the procedures. Finally, the technical aspects and procedural considerations are reviewed.

Frontiers in fetal cardiovascular disease

This article reviews the state of the art in prenatal cardiovascular imaging, the elucidation of regional vascular flow patterns in the developing fetus and what can be learned from these flow patterns, the new clinical practice systems being that are being implemented to deal with the fetal patient and its family, and the prospects for fetal surgery.

Myocardial tissue engineering and regeneration as a therapeutic alternative to transplantation

Ischemic cardiomyopathy leading to congestive heart failure remains the leading source of morbidity and mortality in Western society and medical management of this condition offers only palliative treatment. While allogeneic heart transplantation can both extend and improve the quality of life for patients with end-stage heart failure, this therapeutic option is limited by donor organ shortage. Even after successful transplantation, chronic cardiac rejection in the form of cardiac allograft vasculopathy can severely limit the lifespan of the transplanted organ. Current experimental efforts focus on cellular cardiomyoplasty, myocardial tissue engineering, and myocardial regeneration as alternative approaches to whole organ transplantation. Such strategies may offer novel forms of therapy to patients with end-stage heart failure within the near future.

Long-term experience with the prenatal diagnosis of cardiac anomalies in high-risk pregnancies in a tertiary center

BACKGROUND

The aim of this study was to analyze the role of the prenatal diagnosis of cardiac anomalies in our center.

METHODS

The data of 5540 pregnant women at risk for congenital heart disease and studied at fetal echocardiography between 1984 and 2002, with complete follow-up were retrospectively analyzed.

RESULTS

There was a progressive gradual increase in the number of cases examined per year; 670 fetuses (12% of the population) had congenital heart disease, 6.3% of the milder lesions were not detected. A cardiac arrhythmia was diagnosed in 284 fetuses. Extracardiac and chromosomal anomalies were associated in 23.7 and 14.6% respectively. Recurrence of congenital heart disease was 4.1%. One hundred and seventy-four patients (26%) opted for pregnancy termination; of the 496 fetuses whose parents decided to continue with pregnancy, 10.1% died in utero, 33.7% postnatally and 56.2% survived. The post-surgical mortality was 30.4%. Negative prognostic factors were associated anomalies, heart failure and complex congenital heart disease. Twenty-nine out of 33 fetuses with persistent tachyarrhythmias treated in utero survived; fetuses with complex and isolated atrioventricular block had a 75 and 11.1% mortality.

CONCLUSIONS

Prenatal diagnosis was useful in the management of pregnancy and a planned birth and was life-saving in case of tachyarrhythmia.

Cardiomyocyte transplantation into the failing heart-new therapeutic approach for heart failure?

Heart failure, frequently the consequence of irreversible myocardial damage with subsequent formation of akinetic scar tissue, is a highly prevalent disease, and in its advanced stages associated with high mortality. The transplantation of exogenous cells with the inherent ability to contract has been put forward as one potential treatment strategy to increase contractility and cardiac performance. Besides skeletal myoblasts or stem cells from various sources, immature cardiomyocytes, such as fetal or neonatal cardiomyocytes, have been transplanted into normal, cryoinjured, infarcted myocardium, as well as into models of global heart failure. Survival of transplanted immature cardiomyocytes has been demonstrated up to 6-7 months, accompanied by vascularization of the grafted tissue. Transplants developed sarcomeric structures and other morphological features of differentiation. The principal possibility of cell-to-cell coupling between graft and host cells was demonstrated after cardiomyocyte transplantation into normal hearts and in some studies in damaged myocardium. But most long-term follow-up investigations in models of myocardial infarction reported that optimal integration of the engrafted cells appeared to be hindered by scar tissue, separating the transplant from the host. Nonetheless, in several studies, improved parameters of cardiac performance were demonstrated ex-vivo and in vivo. Potential mechanisms might involve beneficial effects on the remodeling process. In this review, we critically evaluate the potential value of cardiomyocyte transplantation as a new approach in the treatment of the syndrome of "heart failure".

Future of interventional cardiology in pediatrics

A trend toward use of less invasive, nonsurgical approaches to the treatment of congenital heart disease has developed. Although transcatheter valve replacements and ventricular septal defect closures have already been performed in children, many other techniques and devices are being developed for the palliation of children with a single ventricle. Several groups have already established catheter-based procedures for the creation of Fontan communications, and others have performed nonsurgical pulmonary artery banding. Additionally, fetal catheter-based interventions are being developed for the treatment of severe congenital heart disease in utero. Because this trend toward catheter-mediated treatment is certain to continue, care must be taken to regulate safely the introduction of novel techniques and devices into clinical use in pediatric cardiology.

Fetal echocardiography: new grounds to explore during fetal cardiac intervention

Over the past decade, revolutionary advances in ultrasound imaging technology have allowed the study of the evolution of congenital heart disease during fetal life. The frustration arising from watching the prenatal progression of severe semilunar valve obstructions and therapy-refractory fetal arrhythmias has prompted the interest in developing procedures for fetal cardiac intervention. Ultrasound techniques as the primary diagnostic and monitoring modalities in fetal medicine will play a key role in defining patient groups, peri-interventional assessment of fetal hemodynamics, and monitoring during these procedures. The purpose of this article is to provide pediatric cardiologists and perinatal medicine specialists an overview over the various technical approaches at fetal cardiac intervention and the special tasks that fetal echocardiography will have to accomplish. It also aims at illustrating the potential of fetal echocardiography for fetal selection.

Fetoscopic direct fetal cardiac access in sheep : An important experimental milestone along the route to human fetal cardiac intervention

BACKGROUND

Fetal cardiac interventions by direct ultrasound-guided approaches or open fetal cardiac surgery have been fraught with technical difficulties, as well as with significant maternal and fetal morbidity in humans. Therefore, the purpose of our study in sheep was to assess the feasibility and potential of fetoscopic direct fetal cardiac access.

METHODS AND RESULTS

In 15 anesthetized pregnant ewes (88 to 109 days of gestation; term, 145 days), 3 to 4 trocars were percutaneously placed in the uterus. Using videofetoscopic equipment, we assessed the feasibility of achieving direct fetal cardiac access. Minimally invasive direct fetal cardiac access by operative fetoscopy was achieved in 10 of the 15 fetal sheep. In 7 fetuses, the approach was successfully tested for fetal cardiac pacing (n=5) or antegrade fetal cardiac catheterization (n=2). Access was not achieved in 5 fetuses because of bleeding complications (n=2) or because the fetoscopic setup could not be established (n=3). All but 2 fetal sheep were alive at the end of the procedure. Acute fetal demise resulted from maternal hypotension or kinking of the fetal inferior caval vein by sternal suspension. Six ewes continued gestation; 3 of these went to term, with a normal fetal outcome. Two ewes died from septicemia 3 and 7 days after the procedure, and 1 ewe aborted 1 month after the procedure.

CONCLUSIONS

Minimally invasive direct fetal cardiac access by operative fetoscopy is feasible in fetal sheep. The fetoscopic approach carries important potential for fetal cardiac pacing, antegrade fetal valvuloplasties, and resection of fetal intrapericardial teratomas in human fetuses.

Operative techniques and strategies for minimally invasive fetoscopic fetal cardiac interventions in sheep

BACKGROUND

Recent efforts to develop procedures for fetoscopic fetal cardiac interventions have been prompted by the development of severe secondary damage to the fetal heart due to semilunar valvar obstructions and the poor outcome of therapy-refractory fetal arrhythmias. The purpose of our manuscript is to analyze and share our experience with the creation of an operative setup for these procedures in sheep.

METHODS

We studied a total of 48 fetal sheep between 81 and 106 days of gestation (term, 145 days). After entering the amniotic cavity by a percutaneous approach, we performed various fetoscopic fetal cardiac procedures. We analyzed the success of percutaneous fetal access, methods of trocar support, the incidence and management of trocar dislodgement or accidental insertion into the chorioamniotic space, problems related to amniotic insufflation and trocar placement, as well as techniques for fetal posturing and uterine closure.

RESULTS

Percutaneous fetal access was achieved in all sheep. The use of resterilizable trocars substantially decreased the costs of our procedures. Utilizing a percutaneous transuterine purse-string suture for trocar support helped to minimize the number of nonabsorbable T-fasteners remaining inside the uterus postoperatively. As complications such as trocar dislodgement, insertion of the trocar into the chorioamniotic space, and problems with intraamniotic insufflation and gas loss were mastered, conversion to an open operative approach was never required. A novel strategy that we devised for percutaneous fetal posturing permitted adequate fetal posturing with ease and minimal trauma to the fetal skin.

CONCLUSION

As operative techniques have become more refined, the feasibility of performing fetoscopic fetal cardiac interventions in human fetuses now depends mainly on technical improvements in imaging and interventional catheters, as well as advances in pacemaker equipment.

Role of the endothelium in placental dysfunction after fetal cardiac bypass

BACKGROUND

Fetal cardiac bypass causes placental dysfunction, characterized by increased placental vascular resistance, decreased placental blood flow, hypoxia, and acidosis. Vasoactive factors produced by the vascular endothelium, such as nitric oxide and endothelin 1, are important regulators of placental vascular tone and may contribute to this placental dysfunction.

METHODS

To investigate the role of the vascular endothelium in placental dysfunction related to fetal cardiac bypass, we studied 3 groups of fetal sheep. In the first group (n = 7) we determined placental hemodynamic responses before and after bypass to an endothelium-dependent vasodilator (acetylcholine), an endothelium-independent vasodilator (nitroprusside), and endothelin 1. In the second group (n = 8) a nonspecific endothelin receptor blocker (PD 145065) was administered and placental hemodynamic values were measured before and after bypass. In the third group (n = 5) endothelin 1 levels were measured before and after bypass.

RESULTS

Before fetal cardiac bypass exogenous endothelin 1 decreased placental blood flow by 9% and increased placental resistance by 9%. After bypass endothelin 1 decreased placental flow by 47% and increased resistance by 106%. There was also a significant attenuation of the placental vascular relaxation response to acetylcholine after bypass, whereas the response to nitroprusside was not significantly altered. In fetuses that received the PD 145065, placental vascular resistance increased significantly less than in control fetuses (28% versus 62%). Similarly, placental blood flow decreased significantly more (from 6. 3 +/- 3.1 to 28.3 +/- 10.4 pg/mL; P =.01) in control fetuses than in fetuses receiving PD 145065 (33% versus 20%). Umbilical venous endothelin 1 levels increased significantly in fetuses exposed to fetal bypass but did not change in control fetuses.

CONCLUSIONS

The basal endothelial regulatory mechanisms of placental vascular tone were deranged after fetal cardiac bypass. Endothelin receptor blockade, which substantially reduced postbypass placental dysfunction, and other interventions aimed at preserving endothelial function may be effective means of optimizing fetal outcome after cardiac bypass.

Foetal bypass: concepts and controversies

One of the most controversial and challenging surgical undertakings of the next century promises to be foetal cardiac surgery. Animal studies have been underway for several years to gain an understanding of the physiological mechanisms required to achieve this undertaking. Not since the days of crosscirculation has there been a maternal risk associated with open-heart surgery. The diagnosis of congenital heart defects with foetal ultrasound can now be made as early as 12 weeks gestation. Simple cardiac abnormalities, such as valvular stenosis or atresia, alter intracardiac flow patterns and affect normal cardiac chamber development. Without early intervention, these complex lesions often require major surgical reconstruction, beginning in the neonatal period. Foetal cardiac bypass techniques have evolved from the use of roller pumps and bubble oxygenators primed with maternal blood to the use of an axial flow pump incorporated in a right atrial to pulmonary artery or aortic shunt. Because the blood entering the right atrium is oxygenated by the placenta, an oxygenator in the bypass circuit is probably not needed. The low prime axial flow pump system avoids the dilution of the foetus with the maternal adult haemoglobin and improves the outcome. A major focus of research has concentrated on maintenance of placental blood flow with the use of vasodilators and cyclooxygenase inhibitors. Investigation with primates will be necessary to confirm the placental physiology before human operations can be performed. As the foetal bypass challenges are overcome, there is the potential for a reduction in the number of complex cardiac lesions requiring early surgical intervention in the twenty-first century.

[A study of the expression of sarcoplasmic reticulum calcium ATP-ase gene in the left ventricle of the sheep's fetus submitted to chronic increased afterload in utero]

The messenger RNA of the cardiac sarcoplasmic reticulum ATP-ase (SERCA-2a) increases in the left ventricle (LV) during ontogenic development but decreases in hypertrophy induced by increased afterload. Because of the frequency of increased left ventricular overload in congenital heart disease, the authors investigated to see if these increases were likely to interfere with the normal ontogenic program of expression of the SERCA-2a gene in the LV of sheep's foetus. A preductal coarctation of the aorta was realised by banding the transverse aorta (AoT) at 93 days' gestation in 9 foetus (CoA) matched with 9 healthy twin foetus (T). All the foetus underwent haemodynamic, anatomical, histological and molecular biological investigations 4 weeks later. The concentration of SERCA-2a mRNA in the LV was measured by hybridation of a Northern blot with a rat DNAc probe normalised with RNAr 18S. A coarctation was observed in all the CoA group and in none of the T. The ratio of LV weight/body weight was increased in 65% of CoA (p < 0.0001). The concentration of SERCA-2a mRNA in the LV was much reduced in CoA (average -28.6%) of the values observed in T (p = 0.003). Left ventricular hypertrophy of the sheep's foetus induced by pathological increases of afterload surpassed or slowed down the physiological ontogenic maturation of expression of the SERCA-2a gene in abnormalities of cardiac pump function.

Transesophageal echocardiography in fetal sheep. A monitoring tool for open and fetoscopic cardiac procedures

BACKGROUND

Cardiac procedures in exteriorized fetuses or assisted by fetoscopy require monitoring capabilities not attended by conventional maternal transabdominal echocardiography.

METHODS

We, therefore, assessed the potential of fetal transesophageal echocardiography (TEE) utilizing an intravascular ultrasound catheter (IVUC) for fetal cardiac monitoring. We inserted a 10-F-10-MHz IVUC into the esophagus in 12 exteriorized fetal sheep and by a fetoscopic approach in 4 fetal sheep. Cardiac events were observed. Heart rate, cardiac rhythm, patency of the foramen ovale and ductus arteriosus, and the width of the branch pulmonary arteries could be assessed in all fetuses. Ventricular contractility could be assessed only in fetuses weighing less than 2.5 kg. Larger fetuses did not allow adequate imaging of the apical portion of the ventricles because of limited tissue penetration of the IVUC. Fetal TEE permitted placing small guide wires in the cardiac atria and left ventricle. Short-lived premature beats following intracardiac manipulations of these wires could be observed by fetal TEE in all cases.

RESULTS

At autopsy, no complications from IVUC insertion were observed in the exteriorized fetuses. Fetoscopic placement of the IVUC resulted in minor perioral skin erosion in two nonexteriorized fetuses.

CONCLUSIONS

In conclusion, fetal TEE can be achieved with minor fetal injury and may provide useful information during open and fetoscopic cardiac procedures. Further improvements in IVUC design will permit the application of this technique to monitor human fetal cardiac procedures.

Long-term outcome after fetal cardiac bypass: fetal survival to full term and organ abnormalities

BACKGROUND

Earlier work suggests that fetal cardiac bypass is technically feasible but results in significant placental dysfunction. Many of the stimuli that initiate this placental dysfunction have been identified in the past several years and these involve fetal stress, extracorporeal surfaces, priming substances (maternal blood), and flow characteristics. Fetal survival with conventional methods of bypass has been far less than optimal. A novel fetal bypass circuit requiring no priming volume was designed incorporating an in-line axial flow pump (Hemopump, Johnson & Johnson Interventional Systems, Rancho Cordova, Calif.) and was demonstrated to have a marked beneficial effect on placental function.

OBJECTIVE

The purpose of this study was to investigate the effect of this newly developed customized fetal bypass circuit on fetal survival and developing fetal organs.

METHODS AND RESULTS

Nine fetuses at 122 to 126 days of gestation were subjected to fetal cardiac bypass via a transsternal approach, with a 16F single right atrial venous cannula and a 12F arterial cannula. Normothermic cardiac bypass was continued for 30 minutes at flow rates of 320 +/- 32 ml/kg. Of the nine fetuses, one fetus was stillborn 4 days after bypass and eight (89%) were delivered alive after progressing to term gestation. One lamb died of blunt trauma 1 day after birth. All other lambs (n = 7) thrived normally, and at 1 week of age they were subjected to autopsy. No gross hemorrhagic or thromboembolic lesions were detected in the organs examined including the brain. Microscopic examination of representative sections from all organs revealed mild pleural reaction in two lambs, and in two other lambs the hepatocytes showed evidence of mild increase in glycogen content, the significance of which is unknown in relation to fetal bypass. In one fetus that was aborted there was evidence of mild to moderate neuronal loss in the cerebral cortex.

CONCLUSION

This study demonstrates that with improvements in fetal extracorporeal circuitry and techniques very favorable fetal outcome can be achieved. Further studies are necessary to evaluate the effects of bypass on fetal brain in an appropriate animal model. Advances in extracorporeal circuitry to suit the unique fetal physiology increase the possibility of future clinical application.

Cryosurgical ablation of fetal atrioventricular node: new model to treat fetal malignant tachyarrhythmias

BACKGROUND

Sustained tachyarrhythmia resulting in fetal hydrops is often refractory to medical therapy. Fetal atrioventricular node ablation associated with epicardial fetal pacing has the potential to be an effective procedure for this morbid association.

METHODS

To assess the feasibility of therapeutic fetal heart block, we developed a technique of intrauterine cryosurgical ablation of fetal atrioventricular node without the need for cardiac bypass in 8 fetal lambs. Complete heart block was obtained by applying the cryoprobe over the coronary sinus. Fetal pacing was then performed to allow fetal survival.

RESULTS

Complete heart block was achieved in 100% of the fetal lambs. Postoperative evaluation revealed persistent atrioventricular block. The hearts were studied at different postoperative times. Morphologic evaluation of the area containing the cryosurgical lesion revealed varied extension of necrosis of the atrioventricular node and hemorrhage, with involvement of the His bundle and proximal right bundle branch.

CONCLUSIONS

This procedure is technically feasible and offers an alternative approach to the treatment of drug-resistant, life-threatening fetal supraventricular tachyarrhythmias associated with hydrops fetalis.

Laparoscopic ligation of the umbilical cord of an acardiac fetus

We performed umbilical cord ligation using laparoscopic technique in twins with twin reversed arterial perfusion sequence.