Fetal endoscopic tracheal occlusion reduces pulmonary hypertension in severe congenital diaphragmatic hernia

OBJECTIVE

Fetal endoscopic tracheal occlusion (FETO) is associated with increased perinatal survival and reduced need for extracorporeal membrane oxygenation (ECMO) in fetuses with severe congenital diaphragmatic hernia (CDH). This study evaluates the impact of FETO on the resolution of pulmonary hypertension (PH) in fetuses with isolated CDH.

METHODS

We reviewed retrospectively the medical records of all fetuses evaluated for CDH between January 2004 and July 2017 at a single institution. Fetuses with additional major structural or chromosomal abnormalities were excluded. CDH cases were classified retrospectively into mild, moderate and severe groups based on prenatal magnetic resonance imaging indices (observed-to-expected total fetal lung volume and percentage of intrathoracic liver herniation). Presence of PH was determined based on postnatal echocardiograms. Logistic regression analyses were performed to evaluate the relationship between FETO and resolution of PH by 1 year of age while controlling for side of the CDH, use of ECMO, gestational age at diagnosis, gestational age at delivery, fetal gender, sildenafil use at discharge and CDH severity. Resolution of PH by 1 year of age was compared between a cohort of fetuses with severe CDH that underwent FETO and a cohort that did not have the procedure (non-FETO). A subanalysis was performed restricting the analysis to isolated left CDH. Parametric and non-parametric tests were used for comparisons.

RESULTS

Of 257 CDH cases evaluated, 72% (n = 184) had no major structural or chromosomal anomalies of which 58% (n = 107) met the study inclusion criteria. The FETO cohort consisted of 19 CDH cases and the non-FETO cohort (n = 88) consisted of 31 (35%) mild, 32 (36%) moderate and 25 (28%) severe CDH cases. All infants with severe CDH, regardless of whether they underwent FETO, had evidence of neonatal PH. FETO (OR, 3.57; 95% CI, 1.05-12.10; P = 0.041) and ECMO (OR, 5.01; 95% CI, 2.10-11.96; P < 0.001) were independent predictors of resolution of PH by 1 year of age. A higher proportion of infants with severe CDH that underwent FETO had resolution of PH by 1 year after birth compared with infants with severe CDH in the non-FETO cohort (69% (11/16) vs 28% (7/25); P = 0.017). Similar results were observed when the analysis was restricted to cases with left-sided CDH (PH resolution in 69% (11/16) vs 28% (5/18); P = 0.032).

CONCLUSION

In infants with severe CDH, FETO and ECMO are independently associated with increased resolution of PH by 1 year of age. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Pilot study of chronic maternal hyperoxygenation and effect on aortic and mitral valve annular dimensions in fetuses with left heart hypoplasia

OBJECTIVE

Acute maternal hyperoxygenation (AMH) results in increased fetal left heart blood flow. Our aim was to perform a pilot study to determine the safety, feasibility and direction and magnitude of effect of chronic maternal hyperoxygenation (CMH) on mitral and aortic valve annular dimensions in fetuses with left heart hypoplasia (LHH) after CMH.

METHODS

Gravidae with fetal LHH were eligible for inclusion in a prospective evaluation of CMH. LHH was defined as: sum of aortic and mitral valve annuli Z-scores < -4.5, arch flow reversal and left-to-right or bidirectional atrial level shunting without hypoplastic left heart syndrome or severe aortic stenosis. Gravidae with an affected fetus and with ≥ 10% increase in aortic/combined cardiac output flow after 10 min of AMH at 8 L/min 100% fraction of inspired oxygen were offered enrollment. Nine gravidae were enrolled from February 2014 to January 2015. The goal therapy was ≥ 8 h daily CMH from enrollment until delivery. Gravidae who were cared for from July 2012 to October 2014 with fetal LHH and no CMH were identified as historical controls (n = 9). Rates of growth in aortic and mitral annuli over the final trimester were compared between groups using longitudinal regression.

RESULTS

There were no significant maternal or fetal complications in the CMH cohort. Mean gestational age at study initiation was 29.6 ± 3.2 weeks for the intervention group and 28.4 ± 1.8 weeks for controls (P = 0.35). Mean relative increase in aortic/combined cardiac output after AMH was 35.3% (range, 18.1-47.9%). Median number of hours per day on CMH therapy was 9.3 (range, 6.5-14.6) and median duration of CMH was 48 (range, 33-84) days. Mean mitral annular growth was 0.19 ± 0.05 mm/week compared with 0.14 ± 0.05 mm/week in CMH vs controls (mean difference 0.05 ± 0.05 mm/week, P = 0.33). Mean aortic annular growth was 0.14 ± 0.03 mm/week compared with 0.13 ± 0.03 mm/week in CMH vs controls (mean difference 0.01 ± 0.03 mm/week, P = 0.75). More than 9 h CMH daily (n = 6) was associated with better growth of the aortic annulus in intervention fetuses (0.16 ± 0.03 vs 0.08 ± 0.02 mm/week, P = 0.014).

CONCLUSIONS

CMH is both safe and feasible for continued research. In this pilot study, the effect estimates of annular growth, using the studied method of delivery and dose of oxygen, were small. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Congenital heart anomaly in newborns with congenital diaphragmatic hernia: a single-center experience

OBJECTIVE

To evaluate the impact of the presence of a congenital heart anomaly (CHA) and its potential contribution to morbidity and mortality in infants with congenital diaphragmatic hernia (CDH).

METHODS

In this retrospective cohort study, prenatal and postnatal data of all newborns diagnosed with CDH between January 2004 and December 2012 in a single center were reviewed. Cases were classified into two groups: those with 'isolated' CDH and those with both CDH and CHA. Patients with CHA were further subclassified into those with a major or minor CHA based on the Risk Adjustment for Congenital Heart Surgery-1 (RACHS-1), and the Society of Thoracic Surgeons-European Association for Cardiothoracic Surgery (STS-EACTS) scoring systems. Patients with associated non-cardiac anomalies, including 'syndromic cases', were excluded from the analysis. Primary and secondary outcomes were survival up to 1 year of age and a need for extracorporeal membrane oxygenation (ECMO), respectively.

RESULTS

Of the 180 infants with CDH, 41 were excluded because of the presence of non-cardiac associated anomalies, 118 had isolated CDH and 21 had CDH with CHA (16 with minor and five with major CHA). Receiver-operating characteristics curve analysis demonstrated that the best cut-off for survival was when the score for CHA was ≤ 2 for both RACHS-1 (area under the curve (AUC), 0.74 (P = 0.04); sensitivity, 80.0%; specificity, 87.5%) and STS-EACTS (AUC, 0.83 (P = 0.03); sensitivity, 100%; specificity, 87.5%). Survival rate at 1 year was significantly lower in those with CHD and a major CHA (40.0%; P = 0.04) than in those with isolated CDH (77.1%) and those with CDH and a minor CHA (81.3%). We found no significant differences among the groups with regard to the need for ECMO.

CONCLUSIONS

In general, a milder form of CHA does not appear to have a negative impact on the survival of infants with CDH. However, mortality appears to be significantly higher in infants with CDH and a major form of CHA. The scoring systems appear to be useful as predictors for classifying the effects of CHA in this population of patients.

Safety and efficacy of intravenous contrast imaging in pediatric echocardiography

This study was performed to determine the safety and efficacy of intravenous contrast echocardiography in children attending a tertiary cardiac center. This was a prospective study to evaluate the use of Optison contrast agent in children with severely limited transthoracic echocardiographic windows. Twenty children (median age, 15 years; range, 9-18) underwent fundamental imaging (FI), harmonic imaging (HI), and HI with intravenous contrast (Optison FS-069). Endocardial border delineation was determined based on a visual qualitative scoring system (0, none: 4, excellent). Endocardial border definition was significantly improved in all patients using contrast echocardiography (FI vs Optison, p < 0.001 for each). Improved border definition was most dramatic in the apical and left ventricular (LV) free wall regions. Left ventricular ejection fraction (LVEF) was measurable in 20 patients (100%) using contrast compared to 11 (55%) with FI or HI (p < 0.05). The echocardiographic diagnosis was correctly delineated in 1 patient with a severely dyskinetic LV segment only with use of intravenous contrast and HI. No patients suffered adverse hemodynamic effects, changes in taste, or flushing episodes. Three patients experienced transient headaches. Intravenous contrast echocardiography offers an additional tool in evaluating children with very poor transthoracic echocardiographic windows. Such a strategy increases diagnostic accuracy and allows accurate LVEF determination. Adverse hemodynamic effects related to intravenous contrast are exceedingly rare.

Risk factors for neo-aortic root enlargement and aortic regurgitation following arterial switch operation

The objectives of this study were to evaluate changes in dimension of the neo-aortic annulus, aortic root, and aortic anastomosis following arterial switch operation (ASO) and to identify risk factors for developing abnormal neo-aortic root enlargement and aortic regurgitation (AR). Prior studies report development of neo-aortic root dilatation and AR in a small subset of patients after ASO. Predisposing factors for neo-aortic root dilatation and development of moderate/severe AR are poorly understood. We performed a retrospective review of all patients with d-transposition of the great arteries (d-TGA) or double-outlet right ventricle with subpulmonary ventricular septal defect (VSD) who underwent ASO from May 1986 to January 2001. Serial echocardiograms were reviewed to measure neo-aortic annulus, root, and anastomosis diameter (z scores) and to determine progression of AR. Potential risk factors were assessed for developing neo-aortic root enlargement and AR. There were 119 patients (44 female and 75 male): 73 patients had simple d-TGA, 36 had d-TGA with ventricular septal defect, and 10 had a Taussig-Bing heart. The median duration of follow-up was 65 months (range, 12-180). The median neo-aortic root (z = 0.55+/-2.2; p < 0.01) and aortic annulus dimensions (z = 1.57+/-1.75; p < 0.01) were significantly increased over the study period. Aortic anastomosis diameter correlated with growth of the ascending aorta (z = 0.55+/-1.24). Development of severe neo-aortic root enlargement was associated with prior pulmonary artery (PA) banding (p < 0.01), the presence of a VSD (p = 0.03), and Taussig-Bing anatomy (p < 0.01) but was independent of coronary arterial anatomy, coronary arterial transfer technique, or associated lesions (p > 0.05). At latest follow-up, there was no or trivial AR in 88 patients, mild AR in 29 patients, and moderate to severe AR in 3 patients. Risk factors for developing mild or worse AR included severe or rapid neo-aortic root dilatation (p < 0.01). Only 3 patients required surgical intervention for AR. Despite the significant prevalence of neo-aortic root enlargement at intermediate follow-up after ASO, there is a low incidence of significant AR. Prior PA banding, the presence of VSD, and Taussig-Bing anatomy are risk factors for severe root enlargement. Surgical intervention for AR was rare (2%), however, serial surveillance of such patients is vital to monitor for neo-aortic root enlargement and potential aortic valve dysfunction.

Cardiac rhabdomyoma: a report of alternative strategies to surgical resection

Cardiac rhabdomyoma represents the commonest primary cardiac tumour. Its natural history is generally favourable, with resolution in the majority of cases. Surgical resection has been described for intractable arrhythmia, severe obstruction of the inflow or outflow tracts sufficient to compromise cardiac output, and systemic embolization. We describe an alternative palliative strategy, which was associated with regression of the tumour.

Harmonic imaging in fetal echocardiography

Noncontrast harmonic imaging (HI) has been shown to improve image quality in adults with poor acoustic windows. The utility of fetal echocardiography may be limited by suboptimal acoustic windows, and the use of HI in fetal echocardiography has not previously been defined. The purpose of this study was to compare the quality of fundamental imaging (FI) and HI in fetal echocardiography. Sixty-two fetal echocardiograms, including 44 (71%) with limited acoustic windows, were performed with the use of FI and HI. Image quality and visualization of the ventricles, valves, and the aortic and ductal arches were evaluated and compared between FI and HI. Mean HI scores were higher than mean FI scores for all the structures evaluated. Compared with FI, HI improved the image quality and visualization of cardiac structures in this group of fetuses with predominantly suboptimal acoustic windows. Harmonic imaging is a useful adjunct to FI in echocardiography, and the benefits of HI extend to cardiac imaging in the fetus.

Cardiac structure and function in fetuses of mothers infected with HIV: the prospective PCHIV multicenter study

BACKGROUND

This study was designed to determine if vertically transmitted HIV infection and maternal infection with HIV are associated with altered cardiovascular structure and function in utero.

METHODS

Fetal echocardiography was performed in 173 fetuses of 169 HIV-infected mothers (mean gestational age, 33.0 weeks; SD = 3.7 weeks) at 5 centers. Biparietal diameter, femur length, cardiovascular dimensions, and Doppler velocities through atrioventricular and semilunar valves and the umbilical artery were measured. Measurements were converted to z scores based on published normal data.

RESULTS

Fetuses determined after birth to be HIV-infected had similar echocardiographic findings as fetuses later determined to be HIV-uninfected except for slightly smaller left ventricular diastolic dimensions (P =.01). The femur length (P =.03) was also smaller in the fetuses postnatally identified as HIV-infected. Differences in cardiovascular dimensions and Doppler velocities were identified between fetuses of HIV-infected women and previously published normal fetal data. The reason for the differences may be a result of maternal HIV infection, maternal risk factors, or selection bias in the external control data.

CONCLUSIONS

Vertically transmitted HIV infection may be associated with reduced left ventricular size but not with altered cardiac function in utero. Fetuses of HIV-infected mothers may have abnormal cardiovascular structure and function and increased placental vascular resistance, regardless of whether the fetuses are subsequently found to be infected with HIV.

Premature closure of the foramen ovale associated with aortic stenosis, left ventricular dilation with thrombus, and early mortality

Premature foramen ovale (FO) closure has been postulated as a cause of hypoplastic left heart syndrome. We suggest that premature FO closure is also associated with left ventricular (LV) dilation and LV thrombus formation, and that FO closure in patients with aortic stenosis and LV dilation is a secondary event that occurs later in gestation than that seen with the hypoplastic left heart.

The effect of transesophageal echocardiography on ventilation in small infants undergoing cardiac surgery

Transesophageal echocardiography (TEE) is frequently used during congenital cardiac surgery. Complications are infrequent, but interference with ventilation has been reported, especially in small infants. Ventilation variables were measured prospectively in 22 infants, 2-5 kg, undergoing heart surgery with TEE. Measurements were made preoperatively before and after TEE probe insertion and postoperatively before and after TEE probe removal. The variables measured included arterial blood gases, expired tidal volume, peak inspiratory pressure, positive end-expiratory pressure, minute ventilation, airway resistance, dynamic compliance, and peak inspiratory and expiratory flow rates. No significant change in any ventilatory variable at either time period was noted in the infants.

IMPLICATIONS

Ventilatory compromise is infrequent in small infants undergoing transesophageal echocardiography (TEE) examination. Careful ventilatory monitoring rapidly detects changes in ventilation during TEE examination. Small infants who benefit from TEE during heart surgery should not be excluded from receiving a TEE examination because of concern of ventilatory compromise.

The detection of viral genomes by polymerase chain reaction in the myocardium of pediatric patients with advanced HIV disease

OBJECTIVES

The aim of this study was to investigate the frequency of viral nucleic acid detection in the myocardium of human immunodeficiency virus (HIV)-infected children to determine whether an association exists with the development of heart disease.

BACKGROUND

As improved medical interventions increase the life expectancy of HIV-infected patients, increased incidences of myocarditis and dilated cardiomyopathy (DCM) are becoming more apparent, even in patients without clinical symptoms.

METHODS

Myocardial samples were obtained from the postmortem hearts of 32 HIV-infected children and from 32 age-matched controls consisting of patients with structural congenital heart disease and no myocardial inflammation and no cardiac or systemic viral infection. The hearts were examined histologically and analyzed for the presence of viral sequences by polymerase chain reaction (PCR) or reverse transcription-PCR.

RESULTS

Myocarditis was detected histologically in 11 of the 32 HIV-infected patients, and borderline myocarditis was diagnosed in another 13 cases. Infiltrates were confined to the epicardium in two additional hearts. Virus sequences were detected by PCR in 11 of these 26 cases (42.3%); adenovirus in 6, CMV in 3 and both adenovirus and CMV in 2. Two cases without infiltrates were also positive for adenovirus: one had congestive heart failure (CHF) and the other adenoviral pneumonia. No other viruses were detected by PCR, including HIV proviral DNA. All control samples were negative for all viruses tested.

CONCLUSIONS

These data suggest that the presence of viral nucleic acid in the myocardium is common in HIV-infected children, and may relate to the development of myocarditis, DCM or CHF and may contribute to the rapid progression of HIV disease.

Validity of echocardiographic measurement in an epidemiological study. Project HeartBeat!

In Project HeartBeat!, a longitudinal study of cardiovascular disease risk factors in healthy children and adolescents, 3 samples of 40, 80, and 182 echocardiograms, respectively, were randomly selected and reread to evaluate intraobserver and interobserver variabilities and comparability between measurements of field echocardiographic technicians and reference readings at Texas Children's Hospital. Included in the evaluation were 8 M-mode echocardiographic measurements, ie, aortic root diameter, left atrial diameter, and end-diastolic and end-systolic measurements of interventricular septal thickness, left ventricular (LV) diameter, and LV posterior wall thickness; 8 Doppler measurements; and a calculated LV mass. Means and SDs of the differences of the paired measurements were used to assess the relative bias and random error of the measurements. For the intraobserver comparison, means and SDs of the differences were very small, indicating that the echo measurements were performed consistently by each project echo technician. Interobserver comparison showed statistically but not clinically significant differences between the paired readings of end-diastolic septal thickness, end-systolic LV posterior wall thickness, and 5 Doppler measurements. Comparison with reference readings at Texas Children's Hospital showed significant differences in diastolic LV diameter, systolic septal thickness, and right ventricular ejection time. These differences, however, were minimal with limited clinical significance. Mean differences in LV mass for the corresponding comparisons were -1.82, 4.50, and 0.0013 g, and the SDs were 18.79, 24.16, and 12.35 g, respectively. We conclude that the echocardiographic measurements taken from healthy children in a longitudinal study can be made accurately with acceptable reproducibility.

In utero diagnosis of intrapericardial teratoma: a case for in utero open fetal surgery

We present a case of intrapericardial teratoma diagnosed by ultrasound at 26 weeks of gestation presenting as a large tumour mass and rapid development of hydrops fetalis. The fetus died in utero one day before scheduled open fetal surgery.

Outcome of pregnancy following intervention for coarctation of the aorta

There are limited data regarding the outcome of pregnancy in women after intervention for coarctation of the aorta (CoA). The Texas Children's Hospital Cardiac Database was used to identify female patients with CoA born before 1980 who had undergone balloon angioplasty or surgery. Patients with Turner's syndrome and cyanotic congenital heart disease were excluded. A chart review and telephone interview were performed. Data collected included age at intervention, type of intervention, the need for reintervention, functional status, number of pregnancies, and pregnancy outcomes. Seventy-four patients met our criteria and we were able to contact 52. Eighteen patients (39%) were pregnant a total of 36 times. There were 3 spontaneous and 4 elective abortions. Preeclampsia complicated 4 pregnancies in 3 women (17% of primigravidas). One patient had systemic hypertension. Eleven infants were delivered by Cesarean section. There were 29 births, with an average weight of 3.0 kg. There were 5 preterm births, 4 to a teenage mother. Only 1 child (3%) had a congenital heart defect. Thus, in women with an arm-to-leg blood pressure gradient of <20 mm Hg after CoA repair, pregnancy is successful. The occurrence of congenital heart disease in the offspring was 3%. Preeclampsia was similar to that in the general population.

Effects of intravascular transfusion for red cell alloimmunization on fetal arterial blood pressure

OBJECTIVE

To evaluate the effects of intravascular transfusion (IVT) on the fetal umbilical arterial pressure (UAP) in pregnancies complicated by red cell alloimmunization.

STUDY DESIGN

UAP and amniotic fluid pressures (AFP) were measured immediately before and after IVT. Mean UAP was calculated by computing 1/3 (systolic blood pressure - diastolic blood pressure) + diastolic blood pressure. The fractional increase in fetoplacental blood volume with transfusion was calculated by dividing the net volume of blood transfused by the sum of the net volume transfused and the fetoplacental volume based on the estimated fetal weight by ultrasound. Statistical techniques included paired t-test, and the Pearson product correlation. Significance was defined as p < 0.05.

RESULTS

The fetal umbilical artery was punctured during a total of 27 procedures in 21 patients. Pre- and posttransfusion mean UAPs were recorded in 16 of these procedures. Mean UAP increased from 34.0 +/- 14.2 mm Hg pretransfusion to 38.6 +/- 12.8 mm Hg posttransfusion (p = 0.34). There was no correlation between the fractional change in fetoplacental blood volume and the calculated difference between pre- and posttransfusion blood pressure. Bradycardia occurred during 5 procedures (31.2%). Fetal demise occurred after 2 procedures (12.5%).

CONCLUSION

IVT appears to have a minimal effect on the fetal UAP. Fetal bradycardia occurs in a significant percentage of these cases.

Advances in fetal echocardiography

Fetal echocardiography is the primary modality for defining and evaluating fetal cardiac status and requires detailed analysis of the cardiac anatomy from numerous views and Doppler interrogation of the intracardiac structures, great vessels, and umbilical artery. Referrals for fetal echocardiography are determined by fetal, maternal, or familial risk factors; however, approximately 50% of neonates diagnosed with a congenital cardiac defect have no risk factor, and most have undergone an obstetrical ultrasound during the pregnancy that did not detect a cardiac defect. Advances in transducer technology have resulted in the development of small high-frequency transvaginal probes that allow fetal cardiac interrogation earlier during gestation. On the horizon is 3-dimensional fetal echocardiography, which provides rapid image acquisition and tremendous computer image reconstruction ability. At present, the computer image data analysis process is lengthy, and several technical limitations must be overcome before 3-dimensional fetal echocardiography becomes the primary modality of fetal cardiac imaging. New Doppler Tissue Imaging using color Doppler energy mapping allows more precise anatomic definition of the fetal endocardium, facilitating diagnosis of small ventricular septal defects. These new advances, along with improved image resolution, provide obstetricians and pediatric cardiologists with more tools and techniques for earlier and more precise detection of fetuses with cardiac defects.

Intraoperative transesophageal echocardiography in congenital heart surgery. The Texas Children's Hospital experience

Images

Quantitative morphometric analysis of progressive infundibular obstruction in tetralogy of Fallot. A prospective longitudinal echocardiographic study

BACKGROUND

The morphological hallmark of tetralogy of Fallot is controversial, with much disagreement as to whether the subpulmonary infundibulum in this lesion is hypoplastic. In addition, few quantitative data are available regarding the morphometry of the subpulmonary infundibulum, what anatomic characteristics are acquired in the postnatal period, and at what rate they progress. We also sought to determine whether echocardiographic morphometric analysis of the infundibulum can predict clinical course in infants with tetralogy of Fallot.

METHODS AND RESULTS

Twenty-one infants with tetralogy of Fallot (median age at initial study, 1.6 months) were prospectively followed with serial echocardiograms until the time of first surgical intervention (median age at surgery, 10 months). Selected video still frames were digitized off-line with a computerized system. Compared with age-matched normal control infants (n = 37), the following indexed infundibular dimensions in patients with tetralogy of Fallot were significantly smaller: length (1.86 +/- 0.54 versus 2.7 +/- 0.56 cm/BSA0.5, P < .0001), cross-sectional area (1.6 +/- 0.49 versus 4.7 +/- 1.3 cm2/BSA, P < .0001), and volume (1.24 +/- 0.62 versus 7.2 +/- 3 mL/BSA1.5, P < .0001). The following measurements were increased in tetralogy patients: infundibular septal thickness (0.83 +/- 0.21 versus 0.54 +/- 0.06 cm/BSA0.5, P = .0002) and infundibular free-wall thickness (0.62 +/- 0.13 versus 0.49 +/- 0.06 cm/BSA0.5, P = .006). The angle between infundibular septum and ventricular septum had a greater degree of anterosuperior deviation in tetralogy patients, resulting in a larger infundibuloventricular septal angle (77 +/- 8.2 degrees versus 31 +/- 6.5 degrees, P < .0001). During follow-up, infundibular volume in tetralogy patients decreased from 1.24 +/- 0.62 to 0.81 +/- 0.47 mL/BSA1.5 (P = .002), correlating with infundibular septal thickness (r = -.63, P < .003). The mean rate of decrease of indexed infundibular volume was 0.1 +/- 0.13 mL.BSA-15.mo-1. Correlation analysis revealed a nonlinear correlation between the degree of infundibular septal malalignment and indexed infundibular volume (r = .93, P < .0001). Tetralogy patients who required early surgical intervention (4.8 +/- 0.9 versus 10.7 +/- 1.7 months, P < .0001) had a smaller infundibulum at presentation (0.92 +/- 0.35 versus 1.41 +/- 0.67 mL/BSA1.5, P = .04) and an accelerated rate of infundibular narrowing (0.17 +/- 0.18 versus 0.06 +/- 0.08 mL.BSA-1.5.mo-1, P = .04).

CONCLUSIONS

Compared with normal infants, the subpulmonary infundibulum in tetralogy of Fallot is characterized by a smaller volume, shorter and thicker infundibular septum, and anterosuperior deviation of the infundibular septum. Infundibular obstruction in tetralogy patients is progressive, with an average rate of decrease in indexed infundibular volume of 0.1 +/- 0.13 mL.BSA-1.5.mo-1. Infants who are likely to require early therapeutic intervention may be identified on their initial echocardiogram as having an infundibular volume of < 0.9 to 1.0 mL/BSA1.5.

Effects of chronic exercise on blood volume expansion and hematologic indices during pregnancy

OBJECTIVE

To compare blood volumes and hematologic indices between nine aerobically trained, physically active pregnant women who continued to exercise throughout gestation and five healthy yet sedentary gravidas.

METHODS

Subjects were tested on three occasions: 25 and 36 weeks of pregnancy and 12 weeks postpartum. Plasma volumes were estimated by dye dilution with Evans blue. Blood samples were taken from the antecubital vein with the subjects resting in a seated, semirecumbent position. In addition to plasma volume estimations, blood samples were analyzed for hematocrit ratio, hemoglobin concentration, red cell count, and plasma protein concentration. Blood volumes and red cell volumes were calculated from plasma volume estimates and hematocrit ratios.

RESULTS

Average birth weight and length of gestation did not differ between the subject groups. Analysis of variance indicated that absolute blood volume measures were significantly greater (P < .01) in the physically active compared to sedentary subjects at all three test times. Similar results were found for plasma and red cell volumes (P < .01). Blood volumes relative to body weight were significantly higher in physically active subjects (P < .01) than in their sedentary counterparts at 25 weeks (88.5 versus 75.5 mL/kg) and at 36 weeks (88.4 versus 70.9 mL/kg), as well as at 12 weeks postpartum (72.2 versus 57.6 mL/kg). All vascular volumes were significantly (P < .001) lower at 12 weeks postpartum compared to those seen during pregnancy in both subject groups. Hematologic indices of hematocrit ratio, hemoglobin concentration, red cell count, and plasma protein concentration were all greater (P < .001) at 12 weeks postpartum than during pregnancy.

CONCLUSIONS

Physically active women possessed significantly greater vascular volumes than their sedentary counterparts. Although this difference was maintained throughout gestation as the active gravidas continued to exercise, there was no apparent effect on pregnancy outcome.

Effects of maternal aerobic fitness on cardiorespiratory responses to exercise

We hypothesized that aerobically fit women who continued to exercise throughout pregnancy would have enhanced cardiorespiratory responses to exercise. Physically active (N = 10) and sedentary (N = 6) subjects were compared during steady-state (15 min) semi-recumbent cycle exercise performed at a given heart rate (HR; 140 b.min-1) twice during pregnancy (25 wk, 36 wk) and 12 wk postpartum. Indirect calorimetry was used to measure volumes and fractional concentrations of expired gases. Cardiac output was estimated via CO2 rebreathing. Data were analyzed with repeated measures ANOVA. Caloric expenditure during exercise was significantly (P < 0.001) greater in the physically active (7.2 kcal.min-1) compared with sedentary (4.7 kcal.min-1) subjects. Alveolar ventilation and cardiac output responses to exercise were proportionally greater (P < 0.001) in the aerobically fit subjects. Ventilatory equivalents for O2 and physiological dead space/tidal volume ratios were significantly (P < 0.01) lower in the physically active subjects during exercise. In contrast, ratings of perceived exertion during exercise did not differ between subject groups. It appears that a physically active woman's enhanced cardiorespiratory responses to acute exercise are maintained during pregnancy if she continues her aerobic fitness program throughout gestation.

Two-dimensional echocardiographic anatomy of atrioventricular alignment discordance with situs concordance

Relationships between the atria and the ventricles are commonly described in terms of either atrioventricular (AV) alignments (or connections) or AV situs (i.e., the type of atrial situs and the type of ventricular situs or ventricular loop). With either method of analysis, only one type of AV relationship (situs or alignment) is diagnosed specifically and is considered to be predictive of the other type of AV relationship. The two-dimensional echocardiographic characteristics of two patients with incongruent AV situs and alignments are described for the first time. Patient 1 had situs solitus of the viscera and atria (S), ventricular D-loop (D), and solitus normally related great arteries (S), or (S,D,S) segmental combination with concordant AV situs. However, the right-sided right atrium drained into the inferior and right-sided left ventricle, and the left-sided left atrium drained into the superior and left-sided right ventricle. Hence AV alignment discordance was present. Patient 2 had visceroatrial situs solitus (S), ventricular D-loop (D), and double-outlet right ventricle with a rightward aortic valve (D), or (S,D,D) segmental set (AV situs concordance). Similar to patient 1, AV alignment discordance was demonstrated. In both patients the diagnosis was established by two-dimensional echocardiography and subsequently confirmed by cardiac catheterization. The key to accurate echocardiographic diagnosis of this congenital heart disease was independent analysis of the AV alignments and the segmental situs of the three main cardiac segments. This diagnosis was determined by scanning from the parasternal, subxiphoid, and apical windows.(ABSTRACT TRUNCATED AT 250 WORDS)

Indomethacin for preterm labor: fetal toxicity in a dizygotic twin gestation

Indomethacin was given for the treatment of preterm labor in a twin pregnancy at a dosage of 200 mg/day for 7 days beginning at 34 weeks and 5 days' gestation. During treatment, one twin developed closure of the ductus arteriosus, tricuspid regurgitation, right ventricular dysfunction, and pericardial effusion. Severe oligohydramnios in both amniotic sacs appeared as well. All findings resolved within 7 days of discontinuation of the medication. The infants, delivered vaginally at 37 weeks' gestation, were alive and well at a 2-month follow-up visit. We believe that all fetuses of mothers treated with indomethacin should be closely monitored for early evidence of decreased amniotic fluid volume and constriction of the ductus arteriosus.

Maturational differences in the isolated isovolumic rabbit heart

To determine maturational differences in myocardial pressure work, oxygen consumption, and stability, we evaluated an isolated retrogradely perfused isovolumic rabbit heart model in newborns (0-6 days of age, mean 3.3 +/- 1.9 days), immatures (4-6 wk) and adults (5-7 mo). To reduce ischemic time and cardiac trauma, the hearts were isolated and instrumented within the chest cavity. By design, there were no significant age-related differences in coronary flow per gram, heart rate, or resting pressure. Left ventricular developed pressure was similar at all ages, but myocardial oxygen consumption was much lower in newborns and immatures than in adults. Coronary resistance was lower in the younger hearts. There were no significant age-related differences in contractility, left ventricular stiffness, or myocardial pH. All hearts were stable for 120 min, but thereafter immatures and adults deteriorated more rapidly than newborns. The study demonstrates that this model is technically suitable for the study of age-related differences in cardiac physiology. Furthermore, newborn and immature hearts are able to more efficiently use oxygen to develop left ventricular pressures, possibly due to a lower wall tension.

Renal responses to hypoxemia during renin-angiotensin system inhibition in fetal lambs

The role of the renin-angiotensin system (RAS) in modulating the renal hemodynamic and functional responses to hypoxemia was studied in chronically catheterized fetal lambs (132-143 days gestation; term 145 days) before and during administration of either captopril or [Sar1-Gly8]ANG II. Base-line mean arterial blood pressure decreased significantly after administration of either captopril or [Sar1-Gly8]ANG II. This decrease was associated with a significant decline in renal vascular resistance (RVR) in captopril-treated fetuses, whereas no changes in RVR were observed in [Sar1-Gly8]ANG II-treated fetuses. However, the decline in renal blood flow (RBF) and the rise in RVR associated with hypoxemia in control fetuses were not attenuated significantly during inhibition of the RAS using either captopril or [Sar1-Gly8]ANG II. Moreover neither captopril nor [Sar1-Gly8]ANG II blunted the hypertensive response associated with fetal hypoxemia. The renal functional response to captopril was different from the response observed during infusion of [Sar1-Gly8]ANG II. Administration of [Sar1-Gly8]ANG II produced significant decreases in urinary flow rate (UFR), glomerular filtration rate (GFR), and urinary electrolyte (Na+, K+, Cl-) excretion rates, whereas no changes were observed during captopril infusion. The effects of hypoxemia on renal function were not modified after captopril. However, [Sar1-Gly8]ANG II tended to increase UFR and GFR, but these changes were pressure-dependent and not directly related to inhibition of the RAS. This study suggests that the RAS is not an important mediator of the fetal renal hemodynamic and functional responses to hypoxemia.

Factors controlling aldosterone secretion during hypoxemia in fetal lambs

Factors modulating the fetal aldosterone response to hypoxemia were studied in three groups of chronically catheterized fetal lambs between 131 and 143 days of gestation (term, 145 days). One group (control group) received an infusion of 5% dextrose in water; the second group (captopril-treated group) was given captopril, an inhibitor of angiotensin-converting enzyme; the third group (captopril plus dexamethasone-treated group) received dexamethasone in addition to captopril. In all groups of fetuses, hypoxemia was associated with a significant increase in plasma K+ concentration (+0.7 +/- 0.1 meq/liter). In control fetuses, changes in plasma aldosterone concentration during hypoxemia correlated closely with changes in plasma K+ concentration r = 0.79; P less than 0.001) and with changes in plasma angiotensin II concentration (r = 0.77; P less than 0.001). In the captopril-treated fetuses, the rise in plasma aldosterone concentration during hypoxemia correlated closely with plasma K+ (r = 0.79; P less than 0.001) but not with plasma angiotensin II values (r = 0.17). No significant correlation was found between percent changes in maternal aldosterone and percent changes in fetal aldosterone during hypoxemia and following recovery (r = 0.36; P greater than 0.1) in captopril-treated fetuses. Administration of dexamethasone to fetuses receiving captopril completely inhibited the rise in plasma aldosterone associated with hypoxemia. Taken together, the present results suggest that the rise in plasma aldosterone during hypoxemia is not related to the level of activity of the renin-angiotensin system but depends probably on the increased secretion of adrenocorticotrophin by the fetus.(ABSTRACT TRUNCATED AT 250 WORDS)

Near-fatal Kearns-Sayre syndrome. A case report and review of clinical manifestations

The Kearns-Sayre syndrome is a relatively uncommon condition which occurs in childhood and is characterized by neurologic dysfunction and abnormalities in atrioventricular (AV) conduction. The high mortality rate is directly attributable to the cardiovascular manifestations of this syndrome. We report a case, with documentation of a "near-fatal" episode, and review the pertinent clinical features of the syndrome.

Renal and adrenal responses to converting-enzyme inhibition in fetal and newborn life

The renal and adrenal responses to a continuous infusion of the angiotensin-converting enzyme (ACE) inhibitor captopril were studied in 27 chronically catheterized sheep fetuses (less than 120 days gestation, n = 15, and greater than 130 days gestation, n = 12; term being 145 days) and in 12 newborn lambs between 8 and 21 days of age. Total renal blood flow did not change during ACE inhibition. However, the renal vascular resistance decreased significantly in newborn lambs (-21.8 +/- 5.7%) and in fetuses greater than 130 days (-21.7 +/- 4.7%) but not in fetuses less than 120 days. A significant decrease in filtration fraction (-19.2 +/- 6.5%) was observed in newborn lambs. No changes in urinary kallikrein and prostaglandin excretion rate were observed during ACE inhibition in any group of animals. ACE inhibition produced similar declines in blood pressure in both groups of fetuses (-10.2 +/- 3% in fetuses less than 120 days and -9.5 +/- 4.6% in fetuses greater than 130 days) and in newborn lambs (-13.4 +/- 2.1%). The percent changes in plasma renin activity were similar in all groups of animals. However, a significant decline in plasma aldosterone concentration was observed only in newborn lambs (from 130 +/- 31 to 64 +/- 9 pg/ml). These results suggest that the renin-angiotensin system might have physiological significance during maturation, but that this role seems to be more important in near-term fetuses (greater than 130 days) and postnatally than early in gestation.