Role of maternal hyperoxygenation testing to predict need for balloon atrial septostomy in fetal d-transposition of great arteries

OBJECTIVES

Predicting whether balloon atrial septostomy (BAS) will be necessary after birth for fetuses with d-transposition of the great arteries (d-TGA) remains challenging. We sought to determine whether measurements obtained during fetal maternal hyperoxygenation (MH) testing can improve our ability to predict need for postnatal BAS.

METHODS

Forty-one mothers carrying fetuses with d-TGA with either intact ventricular septum or small ventricular septal defect measuring <3mm underwent MH testing between 33-38 weeks gestation. Patent foramen ovale (PFO) size, measured by 2D and color Doppler, patent ductus arteriosus (PDA) shunting (all antegrade versus bidirectional) was assessed in room air (RA) and during MH, blinded to postnatal outcome. BAS status and timing were recorded.

RESULTS

Postnatally, 23 neonates underwent BAS while 18 did not, and 14 subjects underwent emergent BAS within 3 hours of life. By univariate analysis, PFO size measured both in RA and MH and all antegrade shunting in the PDA during MH predicted BAS. During MH testing, median PFO size by 2D measured 2.5mm (interquartile range, IQR, 2-3mm) in fetuses who underwent emergent BAS versus 4.1mm (IQR 3.4-5mm) in fetuses who did not undergo BAS (p<0.001). By cutpoint analysis, PFO size during MH testing ≤ 3.2mm predicted need for emergent BAS with sensitivity 93% and specificity 78%.

CONCLUSIONS

In d-TGA, measurement of PFO size and direction of PDA shunting during MH testing improves our ability to predict need for BAS postnatally, although additional study is needed. We propose incorporating third trimester MH testing when planning deliveries of d-TGA fetuses. This article is protected by copyright. All rights reserved.

Prenatally diagnosed pseudoaneurysm of mitral-aortic intervalvular fibrous area

The mitral-aortic intervalvular fibrosa (MAIVF) is an avascular, fibrous structure that provides continuity between the anterior leaflet of the mitral valve and the aortic valve. Pseudoaneurysm of the MAIVF is rare and has been most commonly described in adults and, more rarely, in children following cardiac surgery or endocarditis. Few reports have been published on cases with congenital pseudoaneurysm of the MAIVF. Here, we describe five cases of congenital pseudoaneurysm of the MAIVF identified prenatally and an additional six cases diagnosed postnatally. This is an unusual finding of varying clinical significance, which can be isolated or associated with complex congenital heart disease but, importantly, can be identified and monitored in the fetus. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Fetal echocardiographic assessment of cardiovascular impact of prolonged support on EXTrauterine Environment for Neonatal Development (EXTEND) system

OBJECTIVE

EXTrauterine Environment for Neonatal Development (EXTEND) is a system to support ongoing fetal growth and organ development in an extrauterine environment, utilizing a pumpless low-resistance oxygenator circuit. The aim of this study was to evaluate hemodynamics and cardiac function in fetal sheep sustained on the EXTEND system.

METHODS

This was a prospective study of fetal sheep supported for a minimum of 3 weeks on EXTEND. Hemodynamic parameters were assessed weekly and included heart rate, mean arterial pressure (MAP), Doppler-echocardiography-derived cardiac output (CO), pulsatility indices (PIs) of the fetal middle cerebral artery (MCA), umbilical artery (UA) and ductus venosus and cardiac function, as assessed by speckle-tracking-derived global longitudinal strain and strain rate in the right (RV) and left (LV) ventricles. Parameters were compared at 0 days and 1, 2 and 3 weeks following placement on EXTEND.

RESULTS

Of 10 fetal sheep enrolled, seven survived for 3 weeks and were included in the analysis. Median gestational age at cannulation was 107 (range, 95-109) days. Heart rate decreased and MAP increased significantly, but within acceptable ranges, during the study period. The quantities and relative ratios of right and left CO remained stable within the anticipated physiological range throughout the study period. Vascular tracings and PIs appeared to be similar to those seen normally in the natural in-utero state, with MCA-PI being higher than UA-PI. UA tracings demonstrated maintained abundant diastolic flow despite the absence of placental circulation. In both the RV and LV, strain decreased significantly at 1 and 2 weeks relative to baseline but returned to baseline values by week 3.

CONCLUSIONS

The EXTEND mechanical support system replicates natural physiology and creates a stable and sustainable cardiovascular construct that supports growth over a 3-week period. However, there is a period of depressed contractility within the first week with subsequent improvement by week 3. This may reflect a period of physiological accommodation that warrants further investigation. This study lays the foundation for further exploration as the EXTEND system moves towards human application. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Cerebrovascular response to maternal hyperoxygenation in fetuses with hypoplastic left heart syndrome depends on gestational age and baseline cerebrovascular resistance

OBJECTIVES

Compared with normal fetuses, fetuses with hypoplastic left heart syndrome (HLHS) have smaller brain volumes and are at higher risk of brain injury, possibly due to diminished cerebral blood flow and oxygen content. By increasing cerebral oxygen delivery, maternal hyperoxygenation (MH) might improve brain development and reduce the risk of brain injury in these fetuses. This study investigated whether gestational age and baseline cerebrovascular resistance affect the response to MH in fetuses with HLHS.

METHODS

The study population comprised 43 fetuses with HLHS or HLHS variant referred for fetal echocardiography between January 2004 and September 2008. Middle cerebral artery (MCA) pulsatility index (PI), a surrogate measure of cerebrovascular resistance, was assessed between 20 and 41 weeks' gestation at baseline in room air (RA) and after 10 min of MH. Z-scores of MCA-PI were generated. A mixed-effects model was used to determine whether change in MCA-PI depends upon gestational age and baseline MCA-PI.

RESULTS

In RA and following MH, MCA-PI demonstrated a curvilinear relationship with gestational age in fetuses with HLHS, peaking at around 28 weeks and then falling more steeply near term. MCA-PI Z-score declined in a linear manner, such that it was 1.4 SD below that in normal fetuses at 38 weeks. Increase in MCA-PI Z-score after MH was first seen at ≥ 28 weeks. A baseline MCA-PI Z-score ≤ -0.96 was predictive of an increase in cerebrovascular resistance in response to MH.

CONCLUSION

In fetuses with HLHS, MCA-PI first increases in response to MH at ≥ 28 weeks' gestation. A baseline MCA-PI Z-score ≤ -0.96 predicts an increase in cerebrovascular resistance in response to MH. These results may have implications for clinical trials utilizing MH as a neuroprotective agent. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Maternal hyperoxygenation improves left heart filling in fetuses with atrial septal aneurysm causing impediment to left ventricular inflow

OBJECTIVES

Aneurysm of the atrial septum (AAS) with excessive excursion of septum primum into the left atrium is an uncommon and relatively benign fetal condition associated with impediment to left ventricular (LV) filling and the appearance of a slender, but apex-forming, LV on fetal echocardiography. Impediment to filling can be severe, creating the image of LV hypoplasia with retrograde aortic flow. We hypothesize that maternal hyperoxygenation alters atrial septal position, improves LV filling, and normalizes aortic flow in fetuses with AAS by increasing fetal pulmonary venous return.

METHODS

Fetal echocardiography was performed prior to, and at 10 min of, maternal hyperoxygenation in 12 fetuses with AAS who were referred to our center because of LV hypoplasia. Atrial septal excursion (ASE), LV and right ventricular (RV) sphericity index (SI) and direction of flow in the aortic isthmus, as determined by Doppler, were measured.

RESULTS

With maternal hyperoxygenation, mean ± SD ASE decreased (0.76 ± 0.17 before maternal hyperoxygenation vs 0.53 ± 0.23 after maternal hyperoxygenation; P < 0.01), consistent with increased pulmonary venous return, LV-SI increased (0.29 ± 0.06 vs 0.42 ± 0.06; P < 0.001), indicating increased LV filling, and the direction of aortic isthmus flow changed from retrograde in all cases prior to maternal hyperoxygenation to antegrade in 10 and to bidirectional in two. RV-SI remained unchanged (0.53 ± 0.13 vs 0.52 ± 0.10; P = 0.7).

CONCLUSIONS

In cases of AAS, short-term maternal hyperoxygenation increases fetal pulmonary venous return, substantially alters LV geometry and promotes antegrade flow in the aortic isthmus. This demonstrates proof-of-concept that maternal hyperoxygenation can improve filling of the left side of the fetal heart in AAS.

Pulmonary outflow tract obstruction in fetuses with complex congenital heart disease: predicting the need for neonatal intervention

OBJECTIVE

To identify prenatal echocardiographic markers that could predict the need for neonatal intervention in fetuses with right ventricular outflow tract obstruction.

METHODS

This was a retrospective study of 52 fetuses with right ventricular outflow tract obstruction. Echocardiograms were evaluated for fetuses with either two-ventricle anatomy with a large ventricular septal defect or single-ventricle anatomy. Fetuses with pulmonary atresia were excluded. Parameters were compared between groups that did and did not require an intervention at age < 30 days.

RESULTS

Fifty-two fetuses were studied; 20 (38%) underwent neonatal intervention and 32 (62%) did not. The most common diagnosis was tetralogy of Fallot (n = 32). Fetuses with two ventricles that required an intervention had lower pulmonary valve diameter Z-score (PV-Z-score) (-4.8 ± 2.1 vs. -2.6 ± 1.1; P = 0.0002) and lower pulmonary valve to aortic valve annular diameter ratio (PV/AoV) (0.53 ± 0.15 vs. 0.66 ± 0.1; P = 0.003). Using a PV/AoV ratio of < 0.6 or a PV-Z-score of < -3 at final echocardiographic examination was highly sensitive (92%) but poorly specific (50%), whereas classifying direction of flow in the ductus arteriosus as either normal (all pulmonary-to-aorta) or abnormal (aorta-to-pulmonary or bidirectional) was both highly sensitive (100%) and specific (95%) for predicting the need for a neonatal intervention. Parameters for the single-ventricle cohort did not reach statistical significance.

CONCLUSIONS

Analysis of the pulmonary outflow tract and ductus arteriosus flow in the fetus with complex congenital heart disease can aid in identifying those that will require a neonatal intervention to augment pulmonary blood flow. This has important implications for the planning of delivery strategies.

Diagnosis and management of heart failure in the fetus

Heart failure can be defined as the inability of the heart to sufficiently support the circulation. In the fetus, heart failure can be caused by a myriad of factors that include fetal shunting abnormalities, genetic cardiomyopathies, extracardiac malformations, arrhythmias and structural congenital heart disease. With advances in ultrasound has come the ability to characterize many complex conditions, previously poorly understood. Fetal echocardiography provides the tools necessary to evaluate and understand the various physiologies that contribute to heart failure in the fetus. In this review, we will explore the different mechanisms of heart failure in this unique patient population and highlight the role of fetal echocardiography in the current management of these conditions.

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

OBJECTIVE

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).

METHODS

Pulsatility indices (PIs) were recorded for the middle cerebral artery (MCA) and the umbilical artery (UA) from 18 to 40 weeks' gestation in 59 fetuses (163 examinations) with SV-CHD with unobstructed aortic flow, yet decreased pulmonary flow, in 72 fetuses (170 examinations) with obstructed aortic flow and hypoplastic left heart syndrome (HLHS) and in 92 normal fetuses (92 examinations). The cerebral-to-placental resistance (CPR) was calculated as the MCA-PI/UA-PI. Z-scores were generated for the MCA-PI and the UA-PI in order to make comparisons independent of gestational age. Statistical analyses were performed using one-way ANOVA with post-hoc testing. Trends in these variables over the course of gestation were assessed using linear regression and univariate ANOVA.

RESULTS

The MCA-PI and the CPR were significantly lower in SV fetuses with aortic obstruction compared with SV fetuses with pulmonary obstruction and with normal fetuses. Moreover, the MCA-PI decreased significantly for SV fetuses with aortic obstruction over the course of gestation. In contrast, the MCA-PI was higher over the course of gestation in SV fetuses with pulmonary obstruction compared with normal fetuses.

CONCLUSION

In fetuses with SV-CHD, cerebrovascular resistance varies substantially between fetuses with and without aortic obstruction. Compared with normal fetuses, cerebrovascular resistance is decreased in SV fetuses with aortic obstruction, yet increased in SV fetuses with pulmonary obstruction. In fetuses with SV physiology, inherent differences in cerebral blood flow may underlie postnatal neurodevelopmental outcomes.

Fetal cardiovascular effects of lower urinary tract obstruction with giant bladder

OBJECTIVE

Lower urinary tract obstruction (LUTO) with massive bladder distension impacts on a variety of developing organ systems with consequent morbidity and mortality. The impact of LUTO on the fetal cardiovascular system has not previously been investigated. We hypothesize that a giant, distended bladder within the pelvis may cause vascular compression with observable consequences.

METHODS

Fetal echocardiography was performed in 42 fetuses with LUTO and compared with 35 normal controls matched for gestational age. Parameters investigated included cardiothoracic ratio, presence or absence of ventricular hypertrophy and pericardial effusion. Doppler echocardiographic examination of mitral and tricuspid valve inflow and the ductus venosus was performed. To assess arterial vascular impedance, pulsatility indices (PIs) were calculated for segments of the descending aorta and right and left iliac arteries (RIA and LIA).

RESULTS

In the LUTO group an increased cardiothoracic ratio was seen in nine (21%), ventricular hypertrophy in 12 (29%) and small pericardial effusion in 15 (36%). Filling characteristics of the right ventricle in the LUTO group demonstrated greater dependency upon atrial contraction, and ductus venosus flow demonstrated higher downstream impedance to filling, than in controls, suggesting altered compliance. The LUTO group also had lower distal descending aorta PI (1.53 ± 0.38 vs. 1.76 ± 0.44, P = 0.04), lower RIA-PI (1.31 ± 0.29 vs. 1.76 ± 0.44, P < 0.001) and lower LIA-PI (1.41 ± 0.44 vs. 1.73 ± 0.31, P < 0.01) than controls, suggesting vascular compression and increased impedance to flow.

CONCLUSIONS

LUTO with giant urinary bladder compresses the iliac arteries, which may lead to increased afterload. Further study is warranted to examine the impact of fetal treatment such as bladder drainage on these cardiovascular parameters.

Perinatal and early surgical outcome for the fetus with hypoplastic left heart syndrome: a 5-year single institutional experience

OBJECTIVES

To review our experience with the prenatal diagnosis of hypoplastic left heart syndrome (HLHS). Our goal was to establish the benchmark for perinatal and early surgical outcome in the current era, from a center with an aggressive surgical approach and a cohort with a high level of intention-to-treat.

METHODS

Outcome was assessed in fetuses with HLHS following stratification into high-risk and standard-risk categories. High risk was defined as the presence of any of the following: extracardiac, genetic or chromosomal anomalies; prematurity of < 34 weeks' gestation; additional cardiac findings such as intact or highly restrictive atrial septum, severe degree of tricuspid regurgitation or severe ventricular dysfunction. Standard risk was defined as absence of these risk factors.

RESULTS

Of 240 fetuses evaluated over 5 years, 162 (67.5%) were in the standard-risk group and 78 (32.5%) were in the high-risk group. Of the 240 sets of parents, 38 (15.8%) chose termination or non-intervention at birth at initial prenatal counseling and 185 of the neonates (77.1%) underwent first-stage Norwood surgery with 155 surviving and 30 deaths, giving an overall Norwood operative survival of 83.8%. Breakdown by risk class reveals a significant Norwood operative survival advantage for the standard-risk group (92.8%) over the high-risk group (56.5%) (P < 0.001).

CONCLUSIONS

Following prenatal diagnosis of HLHS, families should be strongly encouraged to undertake comprehensive prenatal evaluation in order to obtain an accurate prognosis. One-third have additional risk factors that limit survival outcome, however two-thirds do not and have an excellent chance of early survival.

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

OBJECTIVES

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.

METHODS

Doppler flow-derived measures of myocardial performance index (MPI) as described by Tei, ventricular ejection force as described by Isaaz, and combined cardiac output (CCO) were obtained by echocardiography in fetuses with a normal cardiovascular system (n = 76) or CCAM (n = 36) and fetal partners with TTTS (n = 22).

RESULTS

In the CCAM group, systolic performance as evidenced by the ejection forces was preserved, right ventricular (RV) MPI was increased and CCO diminished, suggesting diastolic dysfunction and poor filling secondary to cardiac compression and a tamponade effect. In TTTS, recipient twins exhibited greater left ventricular (LV) ejection forces and higher CCO than donor twins, and had abnormal RV and LV MPI, reflecting increased preload, preserved left systolic performance, but diastolic dysfunction. Donor twins had diminished ejection forces and CCO in comparison with normal controls and recipient partners, reflecting hypovolemia.

CONCLUSIONS

In both CCAM and recipient twins of the TTTS, diastolic dysfunction plays a significant role in the pathophysiology of each disorder and precedes changes in systolic performance. Measures of ventricular performance can help elucidate poorly understood mechanisms of cardiovascular compromise in the developing fetus.

What factors are important to parents making decisions about neonatal research?

BACKGROUND

Although parents of neonates with congenital heart disease are often asked permission for their neonates to participate in research studies, little is known about the factors parents consider when making these decisions.

OBJECTIVE

To determine the reasons for parents' decisions about participation in research studies.

METHODS

Qualitative analysis of the unsolicited comments of 34 parents regarding reasons for agreeing or declining to participate in research studies. Parents' comments were offered spontaneously during interviews about clinical care decisions for neonates with congenital heart disease.

RESULTS

Parents cited five types of reason for or against permitting their newborn to participate in research studies: societal benefit (n = 18), individual benefit for their infant (n = 16), risk of study participation (n = 10), perception that participation posed no harm (n = 9), and anti-experimentation views (n = 4).

CONCLUSION

Addressing parental decision making in the light of these reasons could enhance the parental permission process for parents of critically ill neonates.

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

OBJECTIVES

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.

METHODS

Pulsed Doppler was used to measure blood flow velocities in the umbilical (UA) and middle cerebral (MCA) arteries in 172 fetuses from 20 to 39 weeks' gestational age referred for fetal echocardiography. Pulsatility index (PI), an indicator of downstream vascular resistance, was determined by (peak systolic velocity--end-diastolic velocity)/mean velocity.

RESULTS

Fetuses with hypoplastic left heart syndrome (HLHS; n = 28) had decreased MCA-PI (P = 0.009) compared to normal fetuses (n = 114). Fetuses with right-sided obstructive lesions (RSOL; n = 17) had increased MCA-PI (P = 0.001) when compared to fetuses with HLHS. The UA-PI was elevated in fetuses with RSOLs (P = 0.045).

CONCLUSIONS

Cerebrovascular resistance is lower than normal in fetuses with HLHS, a condition in which cerebral perfusion occurs retrograde via the ductus arteriosus. Fetuses with RSOL had significantly higher cerebrovascular resistance compared to fetuses with HLHS. The type of CHD impacts upon fetal cerebrovascular blood flow distribution and this may have implications for later development of neurological sequelae.

Fetal cardiovascular physiology

The cardiovascular system of the fetus is physiologically different than the adult, mature system. Unique characteristics of the myocardium and specific channels of blood flow differentitate the physiology of the fetus from the newborn. Conditions of increased preload and afterload in the fetus, such as sacrococcygeal teratoma and twin-twin transfusion syndrome, result in unique and complex pathophysiological states. Echocardiography has improved our understanding of human fetal cadiovasvular physiology in the normal and diseased states, and has expanded our capability to more effectively treat these disease processes.

Recurrent arch obstruction after repair of isolated coarctation of the aorta in neonates and young infants: is low weight a risk factor?

BACKGROUND

Repair of aortic coarctation is often delayed in small infants because of the belief that such patients are at risk of recurrent arch obstruction and that growth will decrease this risk. To determine whether low weight was a risk factor for recurrent arch obstruction, we reviewed our experience with coarctation repair via left thoracotomy in infants less than 3 months of age.

METHODS

From 1990 to 1999, 103 patients less than 3 months of age underwent repair of aortic coarctation through a left thoracotomy. Median age was 18 days (1-90 days), with 45 patients less than 2 weeks. Median weight was 3.3 kg (1.0-6.4 kg) and 14 patients were less than 2 kg. The method of repair was resection and end-to-end anastomosis in 64 patients, subclavian flap angioplasty in 34, and patch augmentation of the arch in 5. Demographic, echocardiographic, and operative variables were analyzed for correlation with recurrent arch obstruction.

RESULTS

One early and 1 late death occurred, both in patients who had complications but no evidence of recoarctation. At median follow-up of 24 months, reinterventions for recurrent arch obstruction were performed in 15 patients. The median time to reintervention was 5 months and was less than 1 year in 12 patients. Kaplan-Meier freedom from arch reintervention was 88% at 1 year (95% confidence intervals: 82%-94%) and 82% at 5 years (95% confidence intervals: 72%-92%). Factors associated with shorter duration to arch reintervention by univariable Cox regression included younger age (continuous, P =.01; <2 weeks, P =.005), smaller transverse arch (absolute diameter, P <.001; indexed to weight, P =.03; indexed to ascending aortic diameter, P =.02), and smaller ascending aorta (absolute diameter, P =.02). Smaller absolute transverse arch diameter and younger age were the only independent predictors of shorter time to arch reintervention by multivariable Cox regression analysis. Weight and type of repair did not correlate with risk of recoarctation.

CONCLUSIONS

Low weight is not a risk factor for recurrent obstruction after repair of coarctation of the aorta in infants less than 3 months of age. Rather, risk of recoarctation is more a function of the anatomy of the arch. Thus, it is not indicated to delay repair in low weight infants with the goal of achieving growth.

Design and baseline characteristics for the ACE Inhibitor After Anthracycline (AAA) study of cardiac dysfunction in long-term pediatric cancer survivors

PURPOSE

The ACE Inhibitor After Anthracycline (AAA) study is a randomized, double-blind, controlled clinical trial comparing enalapril with placebo to determine whether treatment can slow the progression of cardiac decline in patients who screen positive for anthracycline cardiotoxicity.

METHODS

The primary outcome measure is the rate of decline, over time, in maximal cardiac index (in liters per minute per meters squared) at peak exercise; the secondary outcome measure is the rate of increase in left ventricular end systolic wall stress (in grams per centimeters squared). Patients >2 years off therapy and <4 years from diagnosis, aged 8 years and older, were eligible if they had received anthracyclines and had at least one cardiac abnormality identified at any time after anthracycline exposure.

RESULTS

A total of 135 patients were randomized to enalapril or placebo. Baseline characteristics were similar across treatment groups.

CONCLUSIONS

The AAA study will provide important information concerning the efficacy of using angiotensin-converting enzyme inhibitors to offset the effects of late anthracycline cardiotoxicity.

Atrioventricular valve regurgitation in patients with single ventricle: impact of the bidirectional cavopulmonary anastomosis

BACKGROUND

It is not known whether atrioventricular valve regurgitation (AVVR) can improve in some patients after the bidirectional cavopulmonary anastomosis (BCPA) without undertaking concomitant valvuloplasty.

METHODS

We retrospectively reviewed our experience with patients who underwent the BCPA between June 1989 and June 2000 with specific attention to those patients with moderate or severe AVVR. The degree of AVVR was determined by color Doppler echocardiography. During the study period there were 576 patients who underwent BCPA at a median age of 6.8 months (range, 1.3 months to 4.8 years). The majority of subjects (66%) had a tricuspid valve as the systemic atrioventricular valve. Significant (moderate or severe) AVVR before BCPA was noted in 36 of 576 patients (6%) and was significantly more prevalent (8 of 52 patients, 15%; p = 0.01) in patients with a common atrioventricular canal.

RESULTS

Of the 36 subjects with moderate or severe AVVR, 8 had interventions (6 valvuloplasty, 2 aortic arch dilation) at BCPA. There was 1 hospital death (2.8%). Of the remaining 27 survivors who did not undergo additional interventions at BCPA, improvement in AVVR (mild or none) was noted in 6 (22%) at intermediate follow-up (median, 2 years; range, 0.5 to 3.1 years). The presence of significant AVVR before BCPA was not significantly associated with hospital survival or intermediate-term freedom from death or transplantation.

CONCLUSIONS

We conclude that AVVR improves in some patients after BCPA and that valvuloplasty is not justified in all patients with moderate preoperative AVVR.

Quantitative echocardiographic assessment of the performance of the functionally single right ventricle after the Fontan operation

BACKGROUND

Performance of the functionally single right ventricle may deteriorate over time. Quantitative assessment of this chamber, however, is complicated by its asymmetric geometry. Automatic detection of borders, and the Doppler-derived index of myocardial performance, are echocardiographic techniques that allow for quantitative assessment regardless of ventricular shape. We sought to evaluate the mechanics of contraction and relaxation in the functionally single right ventricle using these parameters.

METHODS

We evaluated systemic ventricular function in 35 asymptomatic patients with functionally single right ventricle, having a mean age of 7.8+/-3.1 years, who had undergone the Fontan procedure. We compared them with 32 age-matched normal controls using both automatic detection of borders and Doppler indexes.

RESULTS

When compared with the controls, the group with a functionally single right ventricle demonstrated diminished systolic function as evidenced by a lower fractional change in area (42.7+/-10.1% vs. 54.6+/-10.5%, p = 0.001), and diminished diastolic function, as demonstrated by a greater reliance on atrial contraction to achieve ventricular filling (32.0+/-4.4% vs. 22.2+/-4.1%, p = 0.001). The mean index of myocardial performance in those with functionally single right ventricles was also greater than in controls (0.41+/-0.12 vs. 0.30+/-0.05, p = 0.001), and the indexed ejection time was shorter (0.35+/-0.05 vs. 0.39+/-0.05, p = 0.01), suggesting less efficient ventricular mechanics.

CONCLUSIONS

These data demonstrate that the systolic and diastolic properties of the functionally single right ventricle differ significantly from those of the normal systemic left ventricle. Use of the echocardiographic techniques provide insight into ventricular mechanics in patients with functionally single ventricles, and may be valuable tools for serial quantitative follow-up.

Deviation of atrial septum primum in association with normal left atrioventricular valve size

Deviation of atrial septum primum (DASP) is an unusual anatomic finding in patients with normal left atrioventricular valve size. To better describe this anomaly, we reviewed our echocardiographic database from January 1987 to May 1999. Twenty-four patients had DASP and a normal-sized left atrioventricular valve. Six had inferior DASP with common atrioventricular canal. Of these, 3 had evidence of left atrial outlet obstruction. Five survived surgical intervention with follow-up of 24 +/- 14 months. Seventeen patients had superoposterior deviation with the right pulmonary veins draining anomalously to the right atrium. Only 8 of 17 underwent surgical resection; none of the 17 have evidence for late development of obstruction. One patient had both inferior deviation and superoposterior DASP and underwent early successful repair. DASP occurs in patients with normal left atrioventricular valve size. Inferior DASP can result in left atrial outlet obstruction and requires surgical intervention. Superoposterior DASP carries less physiologic consequence. Echocardiography can distinguish this anomaly from other forms of left atrial obstruction.

Thrombus formation after the Fontan operation

BACKGROUND

Thrombus formation is common after a Fontan operation. We investigated the frequency and location of thrombus in our population of children based on the type of Fontan operation performed.

METHODS AND RESULTS

Between January 1987 and January 1999, 592 patients underwent echocardiography after Fontan operation and 52 (8.8%) had intracardiac thrombus. Median age at Fontan operation was 1.9 years (range 0.8 to 35.1). Freedom from thrombus was 92%, 90%, 84% and 82% at 1, 3, 8, and 10 years after Fontan operation, respectively. There was no difference in freedom from thrombus, based on type of operation (atriopulmonary vs. lateral tunnel) or presence of fenestration. Thrombus was detected in the systemic venous atrium in 26 (48%), in the pulmonary venous atrium in 22 (44%), in both atria in 1 (2%), in the hypoplastic left ventricular cavity in 2 (8%), and in the ligated pulmonary artery stump in 1 (2%).

CONCLUSIONS

Thrombus formation occurs with equal frequency in all types of modifications and is seen in the pulmonary, as well as the systemic venous atria. Our study suggests that thrombus formation is inherent to the physiology after Fontan operation and is not related to the type of modification performed.

Evaluation and follow-up of patients with left ventricular apical to aortic conduits with 2D and 3D magnetic resonance imaging and Doppler echocardiography: A new look at an old operation

BACKGROUND

Although the interposition of left ventricular apical to descending aorta conduits has diminished with the advent of the Ross-Konno operation, it remains a useful option. We reviewed our institutional experience imaging these conduits and tested the hypothesis that the gradient across the native left ventricular outflow tract (LVOT) by echocardiography correlated with the conduit gradient by cardiac catheterization. In a patient with an unobstructed conduit, no gradient should exist across the native LVOT.

METHODS

This was a retrospective review of the echocardiography, cardiac catheterization, magnetic resonance imaging (MRI) data, and history of 9 patients with these conduits over an 8-year period. In 7 of 9 patients, 8 conduit obstruction events were assessed by Doppler interrogation of the native LVOT and by cardiac catheterization. Five patients underwent 6 MRI scans.

RESULTS

In all cases of obstruction diagnosed by catheterization (56.3 +/- 21.9 mm Hg), Doppler echocardiography demonstrated gradients across the native LVOT (69.3 +/- 21.2 mm Hg, r = 0.67). Because 2D echocardiography could not visualize the entire conduit in any patient, 2- and 3-dimensional MRI was used successfully to evaluate anatomy and identify the site of obstruction. All patients manifested conduit obstruction. Four (44%) of 9 patients died, 3 underwent the Ross operation, 1 continues to live with his original conduit, and 1 was lost to follow-up.

CONCLUSIONS

A gradient by Doppler interrogation of the native LVOT is an indirect means of assessing conduit obstruction. MRI is a useful tool to complement anatomic diagnosis by echocardiography. Conduit obstruction is common, and late mortality rates appear to be high.

Outcome following tricuspid valve detachment for ventricular septal defects closure

OBJECTIVES

Detachment of the septal leaflet of the tricuspid valve from the annulus (TVD) has been used to improve visualization of ventricular septal defects (VSDs), but may be associated with increased operative time, heart block, and the development of tricuspid regurgitation (TR).

METHODS

Patients undergoing VSD closure between 1/1/96 and 31/12/99 were retrospectively reviewed. Follow-up was obtained from the patients' cardiologists.

RESULTS

Transatrial VSD closure was performed in 172 patients with TVD in 36 (21%) at the surgeon's discretion. The leaflet incision was repaired with a separate suture (22) or with the VSD patch suture (14). Additional procedures including arch augmentation, closure of atrial septal defects, and closure of additional VSDs were performed in 93 (68%) non-TVD patients and 20 (56%) TVD patients. The median age was 6.2 months (range 1 day to 46 years) and the median weight was 5.9 kg (range 1.5-71.5 kg). Cardiopulmonary bypass (CPB) time was 64+/-24 min and cross-clamp time was 34+/-16 min. One hospital death occurred in an infant with tracheal stenosis. No child in either group developed complete heart block. The median duration of postoperative stay was 4 days (range 2-49 days). There were no differences in CPB time, cross-clamp time or postoperative stay between the TVD and non-TVD groups (P>0.1 for all). At a mean follow-up of 17+/-15 months, there have been two late deaths unrelated to cardiac disease. No child in the TVD group required reoperation for residual VSD, compared to three in the non-TVD group. No child in the TVD group has greater than mild TR, but six in the non-TVD group have greater than mild TR. No child in either group has undergone reoperation for TR.

CONCLUSIONS

TVD is a safe, effective technique to improve visualization of VSD and is not associated with heart block, increased operative time, or TR. TVD may result in improved preservation of tricuspid valve architecture and decrease the incidence of significant postoperative TR.

Echocardiographic evaluation of the fetus with congenital cystic adenomatoid malformation

OBJECTIVES

The development of nonimmune hydrops is a known complication of congenital cystic adenomatoid malformation (CCAM) in the fetus. The aim of this study was to investigate the impact of CCAM on hemodynamics in the fetus and to determine whether cardiac dysfunction contributes to the development of hydrops in this patient population.

METHODS

The echocardiographic data from 41 consecutive fetuses diagnosed prenatally with CCAM were reviewed. The presence or absence of hydrops was noted in each patient. Two-dimensional ultrasonographic and Doppler data were compared between the two groups (with or without hydrops).

RESULTS

The mean gestational age for the study group at the time of imaging was 23.2 +/- 3.0 weeks. Hydrops was noted in 15 of 41 fetuses (36.5%). The fetuses that developed hydrops had a lower cardiac/thoracic ratio than those which did not develop hydrops (0.18 vs. 0.23, P = 0.001). The fetuses with hydrops also demonstrated an increase in early ventricular filling. The ratio of early ventricular filling to atrial contraction (E/A ratio) at both the tricuspid and mitral valves was significantly higher in the fetuses with hydrops (P = 0.005 and P = 0.03, respectively). Doppler interrogation of the inferior vena cava demonstrated a greater degree of reversal with atrial contraction in the hydrops group (29.7% vs. 15.1%, P = 0.003). The development of significant atrioventricular valve insufficiency was rare in the fetuses with hydrops (one of 15 cases).

CONCLUSIONS

Cystic adenomatoid malformation can result in significant cardiac compression in the fetus. This alters hemodynamics and may result in hydrops on the basis of elevated central venous pressure.

Evaluation of ventricular septal defect repair using intraoperative transesophageal echocardiography: frequency and significance of residual defects in infants and children

Intraoperative transesophageal echocardiography (IOTEE) is commonly used to assess for residual defect and the need to return to bypass after repair of ventricular septal defect (VSD). The frequency and significance of residual septal defects as noted on IOTEE has not been well defined. We evaluated the frequency of residual VSD via IOTEE and the relationship between size of a residual VSD and rate of reoperation. In addition, we looked at the relationship between the presence of a residual VSD via IOTEE and the presence of residual VSD at follow-up transthoracic echocardiography (TTE). Residual VSD was measured via the largest width of the Doppler color jet diameter originating at the left ventricular septal surface. Of the 294 patients evaluated with IOTEE after VSD repair, one-third had a residual defect by IOTEE Doppler color flow mapping. Two-thirds of these defects closed spontaneously on TTE by the time of hospital discharge. There was no difference in frequency of residual VSD between simple (VSD closure alone, n = 90) and complex (VSD with associated lesions, n = 204) repair. Return to bypass with immediate reoperation was undertaken in nine patients, all of whom had significant shunt via oximetry (Qp/Qs > 1.5:1.0). All had residual VSD color jet diameters > 3 mm. Seven patients had residual color jet equal to 3 mm; however, hemodynamic studies did not reveal a significant shunt and none of these had reoperation. Seven patients with no VSD or < 3 mm residual VSD via had late reoperation to close residual VSD at 4 days to 5 months after initial operation. These were due to patch dehiscence or development of an "intramural" VSD in patients with conotruncal anomaly. A residual defect on IOTEE color Doppler measuring > or = 4 mm predicts the need for immediate reoperation, while a 3 mm defect may be significant and requires additional intraoperative hemodynamic evaluation. The majority of small defects noted on IOTEE are not present at discharge TTE. Patients with conotruncal defect repair should be followed closely for development of late significant "intramural" defects.

Outcome following single-stage repair of coarctation with ventricular septal defect

OBJECTIVE

A recent multi-institutional study suggested improved survival (97%) after staged repair of coarctation with ventricular septal defect (VSD) compared with single-stage repair. The current study was undertaken to determine outcome and need for reintervention following single-stage repair of coarctation and VSD at our institution.

METHODS

Retrospective review of patients undergoing single-stage repair of coarctation with VSD between October 1, 1994 and August 15, 1999.

RESULTS

Single-stage repair of coarctation with VSD was performed in 25 infants (12 males, 13 females) at a median age of 12 days (range 1-87 days) and median weight of 3.3 kg (range 1.3-4.4 kg). The VSD was conoventricular in ten patients, malalignment type with posterior deviation of the infundibular septum in ten, muscular in four and conal septal hypoplasia in one. Arch hypoplasia was present in all patients and bicuspid aortic valve in 13. At least moderate subaortic narrowing was present in six patients (secondary to prolapse of tricuspid valve tissue across the VSD in four). Repairs were performed via a median sternotomy with a mean circulatory arrest time of 38+/-12 min. Overall patient survival was 96% with one operative death and no late deaths at a median follow-up of 16 months (range 1-50 months). Reinterventions included balloon dilatation of recurrent coarctation (five), closure of residual VSD (one) and Ross-Konno procedure (two). Actuarial freedom from reintervention for the hospital survivors was 81% (95% confidence limit (CL) 61%, 92%) at 6 months, 71% (95% CL 47%, 87%) at 1 year and 59% (95% CL 31%, 82%) at 2 years following surgery.

CONCLUSION

Single-stage repair of coarctation with VSD can be performed with low operative mortality and good midterm survival equivalent to reported results for staged repair.

Assessment of pulmonary/systemic blood flow ratio after first-stage palliation for hypoplastic left heart syndrome: development of a new index with the use of doppler echocardiography

OBJECTIVE

Circulatory maldistribution is believed to be a major cause of early death after first-stage palliation for hypoplastic left heart syndrome. Flow reversal in the reconstructed aorta may reflect the pulmonary/systemic blood flow ratio. The purpose of our study was to investigate the utility of arterial PO (2), arterial oxygen saturation, and a newly developed Doppler-derived flow index in predicting the pulmonary/systemic flow ratio after first-stage palliation for hypoplastic left heart syndrome.

METHODS

Twenty-four infants who underwent first-stage palliation for hypoplastic left heart syndrome or a variant were studied. Superior vena cava blood samples were drawn to estimate the mixed venous saturation and permit calculation of the pulmonary/systemic blood flow ratio. Fifty-four samples were evaluated within the first 24 hours after surgery. Simultaneous blood draw and Doppler echocardiography were performed with interrogation in the distal aspect of the arch reconstruction. The ratio of the Doppler velocity-time integral of retrograde flow to the velocity-time integral of forward flow was calculated and compared with the pulmonary/systemic blood flow ratio

RESULTS

The median mixed venous saturation for the 54 samples was low (38.5%; range, 18%-64%). The median calculated pulmonary/systemic blood flow ratio was 1.4:1 (range, 0.3:1 to 4. 2:1). Pulse pressure, mixed venous saturation, and arterial PO (2) were not statistically significant predictors of the measured pulmonary/systemic blood flow ratio. Although both aortic oxygen saturation (R (2) = 0.84, P <.01) and Doppler flow reversal ratio (R (2) = 0.94, P <.001) were significantly associated with the measured pulmonary/systemic blood flow ratio, the model coefficient of determination was greatest for Doppler flow reversal ratio.

CONCLUSION

Measures of arterial oxygen saturation and arterial PO (2) may be misleading in assessing the circulatory status of infants after first-stage palliation for hypoplastic left heart syndrome. Doppler echocardiography, through use of the Doppler flow reversal ratio, provides a more useful measure of pulmonary/systemic blood flow ratio. Low mixed venous saturation after surgery may be due to factors other than pulmonary overcirculation, such as ventricular dysfunction and low cardiac output.

Early results of the Ross procedure in simple and complex left heart disease

BACKGROUND

The Ross procedure has been used increasingly to treat aortic valve disease in children and young adults. Benefits include the lack of anticoagulation after surgery and the potential growth and durability of the autograft. The purpose of this study was to review our institutional experience with the Ross procedure and to compare early outcome in simple aortic valve disease and complex left heart disease.

METHODS AND RESULTS

Between January 1995 and October 1998, 66 patients (median age, 10.8 years; range, 6 days to 34.8 years) underwent the Ross procedure. The primary indication for surgery was isolated valvular disease in 41 patients: aortic stenosis (AS; n=3), aortic insufficiency (AI; n=11), and AS/AI (n=27). The remaining 25 patients had multiple levels of left ventricular outflow tract obstruction, 12 of whom had at least moderate AI. Additional left heart disease in the complex group included subaortic stenosis (n=20), arch obstruction (n=7), mitral valve disease (n=5), apical aortic conduit stenosis or insufficiency (n=3), and supravalvar AS (n=2). There were 123 prior interventions performed in 51 patients, including aortic valvotomy/valvuloplasty (n=56), coarctation repair (n=21), subaortic stenosis resection/Konno procedure (n=10), ventricular septal defect closure (n=8), apical aortic conduit placement (n=3), aortic valve replacement (n=3), and other (n=22). An isolated Ross procedure was performed in 41 patients, 10 of whom required concurrent aortic annulus enlargement procedure to accommodate the larger pulmonary autograft. In the remaining 25 patients, 49 concurrent procedures were performed, including the Konno procedure (n=17), aortic annulus enlargement (n=2), subaortic membrane resection (n=9), arch augmentation (n=5), mitral valvuloplasty (n=5), ventricular septal defect closure (n=4), apicoaortic conduit division (n=3), and other (n=4). One patient (1.5%) died 3 days after a Ross-Konno procedure, which included arch reconstruction, from presumed arrhythmia. There were no other early deaths. One patient required ECMO (extracorporeal membrane oxygenation) for 3 days after a ventricular tachycardia (VT)-related cardiac arrest. Transient complete heart block was seen in 4 patients; the duration was <5 days. No patient had left ventricular outflow tract obstruction on discharge echocardiography. Neo-AI was graded as none (n=5), trivial-mild (n=57), or moderate (n=3). All 3 patients with moderate neo-AI at discharge had abnormal pulmonary valves before surgery. Perioperative VT was noted in 18 patients (27.2%), 2 of whom were discharged on antiarrhythmic medication.

CONCLUSIONS

The Ross procedure can be performed in isolation or in combination with other complex procedures with low mortality (1.5%) and acceptable short-term results, even in patients with complex left heart disease and multiple prior interventions. Postoperative VT is common. Anatomic abnormalities of the pulmonary valve preclude its use as an autograft.

The hypoplastic left heart syndrome with intact atrial septum: atrial morphology, pulmonary vascular histopathology and outcome

OBJECTIVES

The purpose of this study was to investigate the outcome in infants with hypoplastic left heart syndrome and intact atrial septum and to evaluate the relationship of atrial morphology, left atrial decompression pathway and lung histopathology to outcome.

BACKGROUND

In the hypoplastic left heart syndrome, severe restriction at the atrial level results in marked systemic hypoxemia after birth. Infants with intact atrial septum may be at high risk for mortality after Norwood operation.

METHODS

Of 316 infants with hypoplastic left heart syndrome seen at our center over a 6.5-year period, 18 (5.7%) had intact atrial septum. Medical records and echocardiograms were reviewed.

RESULTS

On echocardiography, three types of intact atrial septal morphology were identified: 1) large left atrium, thick prominent septum secondary with thin septum primary adherent (type A, n = 12); 2) small left atrium with thick, muscular atrial septum (type B, n = 4), and 3) giant left atrium, thin atrial septum with severe mitral regurgitation (type C, n = 2). Seven infants had left atrial decompression pathways that were severely obstructed (3/12 type A, 4/4 type B). Norwood operation was performed in 17 infants; one underwent emergency balloon atrial septostomy and died. Of six early survivors, all with type A atrial morphology and unobstructed decompression pathway, three died after subsequent cavopulmonary surgery. Lung histopathology revealed severely dilated lymphatics and "arterialization" of the pulmonary veins in those with the severest degree of obstruction to left atrial egress (type B atrial morphology).

CONCLUSIONS

Despite aggressive intervention, outcome for infants born with hypoplastic left heart syndrome and intact atrial septum is poor. Maldevelopment of the pulmonary vasculature contributes to the high mortality seen. Atrial morphology can be used as a marker for the severity of pulmonary vascular disease.

Outcome after repair of tetralogy of Fallot with absent pulmonary valve

BACKGROUND

Tetralogy of Fallot with absent pulmonary valve (TOF/APV) is associated with pulmonary artery dilatation and airway compression.

METHODS

Since January 1, 1984, 28 patients with TOF/ APV have undergone complete repair (median age 11 days, range 1 day to 16 years).

RESULTS

Thirteen patients were ventilated for respiratory failure preoperatively and extracorporeal membrane oxygenation was used in 3. Twenty-six patients underwent pulmonary artery plication (11 anterior, 15 anterior/ posterior). The right ventricular outflow tract (RVOT) was reconstructed with a patch (19), valved conduit (5), or monocusp valve (4). Early mortality was 21.4% (6/28), with 1 late death. All early deaths occurred in infants intubated preoperatively. Survival was 77% (95% confidence limit [CL] 56%, 89%) at 1 year and 72% (95% CL 50%, 86%) at 10 years. After surgery, 3 patients underwent reoperation for persistent respiratory symptoms, which resolved after repeat plication and placement of a valved conduit. Freedom from death or reoperation was 68% (95% CL 46%, 83%) at 1 year and 52% (95% CL 29%, 71%) at 10 years. In a multivariable analysis, only preoperative intubation was associated with a worse outcome (p = 0.04).

CONCLUSIONS

Long-term outcome for patients with TOF/APV who survive the initial repair is good. Repeat plication and pulmonary valve implantation may improve outcome in patients with persistent airway compression.

Pulmonary hypertension in children following extracorporeal membrane oxygenation therapy and repair of congenital diaphragmatic hernia

OBJECTIVE

Pulmonary hypertension (PHT) is present in all children at birth, but its degree and rate of resolution in infants diagnosed with congenital diaphragmatic hernia (CDH) requiring extracorporeal membrane oxygenation (ECMO) need to be established.

STUDY DESIGN

Twenty-one ECMO/CDH survivors (aged 3.2 +/- 1.4 years) were prospectively evaluated by Doppler echocardiography (ECHO) to determine the presence of PHT. Twenty children without structural heart disease were used as controls. Study patients received a physical examination and an electrocardiograph examination, and their charts were reviewed for neonatal course data. Patients found to have PHT by ECHO received a complete history and exercise treadmill/oxygen desaturation study.

RESULTS

Eight of the 21 patients (38%) met echocardiographic criteria for PHT. No neonatal course data were found to be predictive of eventual PHT status. There was no correlation between physical examination or electrocardiographic findings and PHT. Complete histories showed five of the eight patients with PHT had some degree of exercise intolerance and seven had wheezing. Two of the seven patients studied on the treadmill desaturated 5% or greater from baseline.

CONCLUSION

There is evidence that PHT either persists or recurs in a significant portion of the ECMO/CDH population and may remain symptomatic well beyond the neonatal period.

Caval contribution to flow in the branch pulmonary arteries of Fontan patients with a novel application of magnetic resonance presaturation pulse

BACKGROUND

A complete understanding of fluid mechanics in Fontan physiology includes knowledge of the caval contributions to right (RPA) and left (LPA) pulmonary arterial blood flow, total systemic venous return, and relative blood flow to each lung.

METHODS AND RESULTS

Ten Fontan patients underwent cine MRI. Three cine scans of the pulmonary arteries were performed: (1) no presaturation pulse, (2) a presaturation pulse labeling inferior vena cava (IVC) blood (signal void), and (3) a presaturation pulse labeling superior vena cava (SVC) blood. The relative signal decrease is proportional to the amount of blood originating from the labeled vena cava. This method was validated in a phantom. Whereas 60+/-6% of SVC blood flowed into the RPA, 67+/-12% of IVC blood flowed toward the LPA. Of the blood in the LPA and RPA, 48+/-14% and 31+/-17%, respectively, came from the IVC. IVC blood contributed 40+/-16% to total systemic venous return. The distributions of blood to each lung were nearly equal (RPA/LPA blood=0.94+/-11).

CONCLUSIONS

In Fontan patients with total cavopulmonary connection, SVC blood is directed toward the RPA and IVC blood is directed toward the LPA. Although the right lung volume is larger than the left, an equal amount of blood flow went to both lungs. LPA blood is composed of equal amounts of IVC and SVC blood because IVC contribution to total systemic venous return is smaller than that of the SVC. This technique and these findings can help to evaluate design changes of the systemic venous pathway to improve Fontan hemodynamics.