Fetal echocardiographic diagnosis of congenital heart disease

Prenatal effects of maternal consumption of polyphenol-rich foods in late pregnancy upon fetal ductus arteriosus

Fetal circulation has characteristic features, being morphologically and functionally different from extrauterine circulation. The ductus arteriosus plays a fundamental role in directing the blood flow to fetal inferior body parts. Basically, the ductus arteriosus directs 80-85% of the right ventricular output arising from the superior vena cava, coronary sinus, and a small part from the inferior vena cava to descending aorta. Its histological structure is made up predominantly by a thick muscular layer, differently from the aorta and the pulmonary artery, which increases with gestational age. The fibers have a circumferential orientation, especially at the external layers, facilitating and making effective ductal constriction. These factors may generate lumen alterations which may cause fetal and neonatal complications, such as heart failure, hydrops, neonatal pulmonary hypertension, and even death. Classically, maternal administration of indomethacin and/or other antiinflammatory drugs interfere in prostaglandins metabolism, causing ductal constriction. However, many cases of fetal ductal constriction, as well as of persistent neonatal pulmonary artery hypertension, remain without an established etiology, being referred as "idiopathic." In recent years, a growing body of evidence has shown that herbs, fruits, nuts, and a wide diversity of substances commonly used in daily diets have definitive effects upon the metabolic pathway of inflammation, with consequent inhibition of prostaglandins synthesis. This antiinflammatory action, especially of polyphenols, when ingested during the third trimester of pregnancy, may influence the dynamics of fetal ductus arteriosus flow. The goal of this review is to present these new observations and findings, which may influence dietary orientation during pregnancy.

Morphometric study of the ventricular segment of the human fetal heart between 13 and 20 weeks' gestation

Our objective was to determine the normal dimensions of the ventricular segment of the human fetal heart between 13 and 20 weeks' gestation.

STUDY DESIGN

103 hearts obtained by necropsy were dissected and measurements of different portions of ventricles were determined under stereoscopic magnification. In each ventricle were measured anteroposterior and lateral diameters, inlet and outlet length, and thickness of walls at different levels. Our results showed the cardiac apex was constituted by the left ventricle in 68.9% of the hearts. Both ventricles showed linear growth during this period of fetal development. Ranges in median values of external and internal ventricular measurements were determined. The left ventricular wall was thicker than the right, and the right ventricular cavity was larger. This study provides morphometric reference information concerning the dimensions and growth of both ventricles of the fetal heart, which may be useful in pediatric cardiac surgery and echocardiography.

Morphometric study of the human fetal heart I. Arterial segment

This study measured the dimensions of the great arteries of normal human fetal hearts at an early fetal stage (between 13-20 weeks post-fertilization) in 103 fetuses obtained by necropsy. Different segments of the aorta and the pulmonary artery were dissected and their external diameters measured under stereoscopic magnification. All segments showed linear growth during this period of fetal development. Ranges in median values of external diameters associated with the pulmonary artery were: 2.1-4.2 mm for the valve ring; 2.2-4.2 mm for the main pulmonary trunk; 1.2-2.5 mm for the right pulmonary artery; 0.9-2.18 mm for the left pulmonary artery; and 4.0-8.0 mm for the length of the main pulmonary trunk. Similarly, in the aorta, median diameters were: 2.1-4.2 mm for the ascending aorta; 1.92-3.8 mm for the aortic arch; 1.45-3.0 mm for the aortic isthmus; and 1.75 -3.35 mm for the descending aorta. The diameter of the ductus arteriosus ranged between 1.2-2.45 mm. The growth rates of the pulmonary artery and the aorta were similar. The diameter of the ascending aorta was found to be greater than that of the descending aorta and the right pulmonary artery was wider than the left pulmonary artery. In addition, the magnitude of growth in the various aortic segments was different and the ratios obtained between the aortic isthmus and the ascending and descending aortae, ranged between 0.66-0.93. This study provides important morphometric reference information concerning the dimensions and growth of the great arteries of the fetal heart and has clinical application in pediatric cardiac surgery and echocardiography.

The monolithic fetal pacemaker: prototype lead design for closed thorax deployment

Prenatal sudden cardiac death and hydrops fetalis are often due to complete heart block. However, no pacing modality exists for intrauterine application for fetal bradycardia. A prototype lead for a novel fetal pacemaker has been developed and used in a direct pacing model. It has been demonstrated that the lead can be safely and successfully deployed using a hypochondriac and transdiaphragmatic or subxiphoid approach. Pacing with ventricular capture was evident with the widening of QRS duration from 50.2 +/- 9.8 to 95.1 +/- 12.8 ms (P = 0.0001). Further studies by echocardiogram revealed an increase in the pulse with pacing, confirming pacing. This study documents proof-of-concept for closed thorax over-the-wire deployment of a novel lead design applicable to fetal pacing. By combining the lead design with microcircuitry and a small power source, it is possible to create a monolithic fetal pacemaker system capable of being deployed in utero.

Perinatal induction of immunotolerance to cardiac and pulmonary allografts

OBJECTIVES

Tolerance appears to be more easily induced in the fetus before full immunocompetence is established, but elucidation of this process is needed. A model of perinatal tolerance induction to neonatal skin allografts followed by cardiac and pulmonary allografts is described.

METHODS

Sixty Lewis (RT11) rat fetuses were inoculated intraperitoneally at 18 days gestation with 1 x 10(7) ACI (RT1a) rat fetal liver cells (group I); 20 Lewis fetuses were inoculated with 2 x 10(7) ACI fetal liver cells (Group II). control groups consisted of Lewis fetuses inoculated with saline solution (n = 25, group III) and fetuses that were not inoculated (n = 25, group IV). Twenty-five of the 50 surviving group I rats received ACI skin (< 24 hours old) and heart (8 to 10 weeks old) allografts (group IA); the remaining 25 rats received only ACI heart grafts (group IB). Groups II, III, and IV received ACI skin and cardiac allografts. Recipients tolerant to both skin and cardiac grafts received orthotopic ACI lung grafts and third-party skin grafts. Tolerance was indicated by graft survival for more than 100 days. Limiting dilution and flow cytometric analyses were performed.

RESULTS

Abortion rates in groups I, II, III, and IV were 17% (10/60), 65% (13/20), 8% (2/25), and 4% (1/25), respectively. Specific tolerance to skin, cardiac, and lung allografts was observed in seven of 25 group IA recipients (28%) and seven of seven group II recipients (100%) compared with no tolerance in any group IB, III, or IV recipients (p = 0.03, chi 2 test). A 100-fold reduction of precursor cytotoxic T lymphocytes and significant splenocyte and bone marrow chimerism in tolerant versus nontolerant rats were noted (p = 0.0001, Student's t test).

CONCLUSIONS

Using donor-strain fetal liver cells and neonatal skin grafts, we achieved higher frequencies of tolerance to solid organ grafts in adulthood with lower cell inocula and abortion rates than previously described. Chimerism and depressed precursor cytotoxic T lymphocyte frequencies in tolerant recipients suggest that hematopoietic stem cell engraftment and clonal deletion/anergy are involved in induction of perinatal tolerance.

Pregnancy outcomes after the Fontan repair

OBJECTIVES

This study sought to determine risks and outcome of pregnancy and delivery after the modified Fontan operation.

BACKGROUND

Increasingly, female Fontan patients reaching child-bearing years are interested in having children. To date, the number of reported pregnancies is small, and pregnancy has therefore been discouraged.

METHODS

One hundred ten of 126 female patients from the Fontan registries of the Mayo Clinic and University of California Los Angeles Medical Center responded to a mailed questionnaire. An additional six patients with a reported pregnancy from other centers were identified and reviewed to assess pregnancy outcomes.

RESULTS

Among the participating centers, a total of 33 pregnancies after Fontan operation for various types of univentricular heart disease were reported. There were 15 (45%) live births from 14 mothers, with 13 spontaneous abortions and 5 elective terminations. In the 14 women with live births, the median number of years between operation and pregnancy was 4 (range 2 to 14). Reported prepregnancy problems in these gravidas included atrial flutter in one patient and ventricular dysfunction, aortic regurgitation and atrioventricular valve regurgitation in another. One patient developed supraventricular tachycardia during pregnancy and had conversion to sinus rhythm. No maternal cardiac complications were reported during labor, delivery or the immediate puerperium. There were six female and nine male infants (mean gestational age 36.5 weeks; median weight 2,344 g). One infant had an atrial septal defect. At follow-up, mothers and infants were alive and well.

CONCLUSIONS

Pregnancy after the Fontan operation appears to have been well tolerated in 13 to 14 gravidas. There does appear to be an increased risk of miscarriage. The tendency to routinely discourage pregnancy may need to be reconsidered.

Development of tolerance to experimental cardiac allografts in utero

"Actively acquired tolerance" to foreign cells was described in 1953 by Medawar and colleagues and formed the basis for subsequent efforts in organ transplantation. We have applied these historic principles of intrauterine immune manipulation in a vascularized cardiac allograft model. Allogeneic Lewis-Brown Norway (LBN) splenocytes (0 to 5 x 10(7) cells) were injected intraperitoneally into each fetus of a pregnant Lewis rat at day 14 to 16 of gestation, when T cells are "educated" to distinguish self from foreign. This manipulation causes fetal attrition inversely proportional to the number of cells injected. Heterotopic transplantation using an LBN heart was carried out in each surviving fetus at 6 to 8 weeks of age. Untreated Lewis rats rejected LBN hearts within 7.6 days. Rats receiving LBN splenocytes in utero demonstrated prolongation of graft survival proportional to the number of cells given. Surviving animals exposed to 5 x 10(7) allogeneic cells in utero (n = 4) had graft survivals of 24 to more than 150 days (mean, 88.0 days), significantly longer than control animals (6 to 10 days; mean, 7.6 days; p < 0.02). Significant prolongation of cardiac allograft survival and in some cases complete tolerance can be achieved by intrauterine exposure to allogeneic cells at a critical period of immunologic development. Because many serious cardiac defects amenable to treatment by cardiac transplantation can be detected by ultrasound early in gestation, treatment based on this strategy may become useful in pediatric heart transplantation.

Definition of inseparably fused ventricular myocardium in thoracopagus: fetal echocardiographic utility and pathologic refinement

Correlative echocardiographic and pathological findings in a thoracopagus with conjoined hearts are reported. One twin had tricuspid atresia with discordant atrioventricular connections and concordant ventriculoarterial connections. The morphologic right ventricle was hypoplastic and there was a large muscular ventricular septal defect. The other twin had hypoplasia of the mitral valve anulus and left ventricle with double-outlet right ventricle and pulmonary valve atresia. The tricuspid valve was severely insufficient in part because of a large orifice and redundant, elongated leaflets with abnormal chordal attachments. The left ventricles of these two twins shared a perforated common "free wall" with at least two large defects allowing mixing of the circulations at that level. Not all anatomic details were established conclusively by fetal echocardiography; however, sufficient diagnostic information was obtained to support a decision not to aggressively resuscitate these twins after elective cesarean delivery at 31 weeks' gestation.

Sonographic assessment of fetal cardiac arrhythmias

The fetus with an arrhythmia may be at high risk both from the arrhythmia itself and from the condition that provoked it. Incorrect diagnosis and inappropriate or delayed treatment may further compound the hazard. Although echocardiography can specifically identify the arrhythmia, this technique requires very skilled and careful examination by a physician who fully understands how to differentiate optimally between similar-appearing but mechanistically different arrhythmias. Congenital heart disease may also be present and must be evaluated specifically. This report describes ultrasound recording techniques used to diagnose arrhythmias and includes a discussion of M-mode echocardiography, two-dimensional imaging, pulsed Doppler, and color-flow Doppler. It also differentiates specific arrhythmias--premature atrial contractions, ventricular tachycardia, atrial flutter, complete heart block, and supraventricular tachycardia--and presents the optimal diagnostic tools for each.

Ebstein anomaly: report of a familial occurrence and prenatal diagnosis

The Ebstein anomaly is a rare congenital heart disease involving the position and structure of the tricuspid valve. Although most cases are sporadic, familial occurrence has been documented. We report on 2 sisters, born to consanguineous parents, who were diagnosed prenatally with severe Ebstein anomaly.