Klaus G. Schmidt

Cardiac Dimensions Determined by Cross-Sectional Echocardiography in the Normal Human Fetus from 18 Weeks to Term

Assessment of cardiac dimensions of the chambers, great arteries and veins in the human fetus is important to distinguish abnormal dimensions from normal. This study establishes normal values based on cross-sectional echocardiographic measurements over the gestational period where these measurements may be clinically useful. Ventricular and atrial dimensions were measured from the 4-chamber view, the short-axis dimension immediately below the mitral and tricuspid valve leaflets in diastole, and the long axis from the closed apposed atrioventricular valves to their respective apices. The ventricular walls and septum were measured at the level at which cavity dimensions in diastole were measured, defining both the left and right ventricular wall thickness, as well as that of the ventricular septum. Furthermore, the long axis of the right and left atria was measured from the center of the apposed atrioventricular valve leaflets to the posterior atrial wall, and the sizes of the atrial chambers were defined using their widths at the prospective broadest points through the area of foramen ovale. From a variety of views, diameters were measured at maximal expansion of the main, left and right pulmonary arteries, the ductus arteriosus, and the superior and inferior venae cavae. The data were evaluated longitudinally from 18 weeks to term, and regression analysis was performed using the best fit of a linear or polynomial equation. The data provide a means for evaluating the normal sizes and dimensions of the fetal heart chambers, as well as the thickness of the ventricular walls and septum.

DEATH DUE TO HIGH-OUTPUT CARDIAC FAILURE IN FETAL SACROCOCCYGEAL TERATOMA

Fetal sacrococcygeal teratoma (SCT) is being recognized with increasing frequency. Placentomegaly and hydrops fetalis are preterminal events, and it has been suggested that fetal death may be due to high-output cardiac failure from arteriovenous shunting through the tumor. We had a chance to examine this hypothesis when a 21-week fetus presented with a huge sacrococcygeal teratoma. There were marked placentomegaly, cardiomegaly, hyperdynamic ventricles, and a pericardial effusion. Doppler studies showed tremendous flow through the SCT with extreme enlargement of the inferior vena cava, consistent with congestive heart failure from increased flow through the tumor. Hydrops developed, and the fetus was delivered because of placental abruption. This case provides supportive evidence that the teratoma acts as a large arteriovenous shunt, causing high-output cardiac failure. We have now collected 18 more cases of sacrococcygeal teratoma diagnosed in utero. Of the total 45 cases of fetal SCT, 9 had placentomegaly and/or fetal hydrops and all 9 fetuses died in utero or shortly after birth. We conclude that the only hope for survival in these severely affected fetuses is to reduce blood flow to the tumor before birth.

Complications of pediatric cardiac catheterization: A 3-year study

To determine the current risk of pediatric cardiac catheterization, the complications and incidents of all catheterizations performed in a pediatric laboratory between January 1986 and October 1988 were prospectively recorded and compared with results from a 1974 study from the same institution. In the current study 1,037 catheterizations, 885 diagnostic and 152 diagnostic/interventional procedures, were performed in 888 patients (aged 1 day to 27 years, median 15.6 months). There were 15 major complications (1.4%), 70 minor complications (6.8%) and 30 incidents (2.9%). Two patients died as a result of the procedure and two as a result of pericatheterization clinical deterioration caused by the cardiac abnormality. The great majority of complications were successfully treated or were self-limited and the patients had no residua. Of patients with 13 nonfatal major complications and 70 minor complications, residua were evident in 7 patients and 3 without evident residua had the potential for sequelae (0.7% and 0.3% of catheterizations). A comparison of the diagnostic and balloon atrial septostomy cases in the present study with similar cases in the 1974 study shows that the incidence of major complications has decreased from 2.9% to 0.9% (p less than 0.0001); minor complications and incidents have decreased from 11.7% to 7.9% (p less than 0.006) and pericatheterization deaths not attributable to catheterization have decreased from 2.8% to 0.2% (p less than 0.0001). Changes in pericatheterization medical management, patient selection for catheterization and catheterization techniques probably account for these improvements.

Diagnosis of coronary artery fistula by two-dimensional echocardiography, pulsed doppler ultrasound and color flow imaging

Ten consecutive patients with a coronary artery fistula, aged 1 day to 4 years, were studied by two-dimensional echocardiography, pulsed Doppler ultrasound and color flow imaging. All patients underwent cardiac catheterization, and seven patients had surgical closure of the fistula. The origin, course and site of drainage of the coronary artery fistula were correctly identified prospectively by echocardiographic examination in all patients. Color flow imaging was particularly helpful in visualizing the site of drainage of the fistula. Diameters of the right and left coronary arteries at their origin and of the aortic root were measured from two-dimensional echocardiographic frames and compared with measurements obtained in normal children. The ratio of coronary artery diameter to aortic root diameter in normal children was 0.14 +/- 0.03 (mean +/- SD) for the right coronary artery and 0.17 +/- 0.03 for the left coronary artery. These normal ratios were greatly exceeded for coronary arteries feeding the fistula, and ranged from 0.68 to 0.84 for the right coronary artery and from 0.34 to 0.52 for the left coronary artery. All anatomic information needed for surgical treatment of coronary artery fistula was consistently obtained by echocardiography with color flow imaging. The fistula was closed from within the heart in five patients and by ligation from the epicardial surface in two patients. In these latter patients, intraoperative color flow imaging at the time of ligation proved to be extremely valuable in achieving complete closure.

High-output cardiac failure in fetuses with large sacrococcygeal teratoma: Diagnosis by echocardiography and Doppler ultrasound

With two-dimensional echocardiography and Doppler ultrasound, we demonstrated high-output cardiac failure in three fetuses with large sacrococcygeal teratomas. All fetuses had normal cardiac structure, dilated ventricles maintaining a normal fractional shortening index, a dilated inferior vena cava reflecting the increased venous return from the lower body, pericardial and pleural effusions as a manifestation of fetal hydrops, and a markedly thickened placenta. When fetal hydrops was present, the combined ventricular output was very high (mean 1280 ml/min/kg; normal 553 +/- 153 (SD)). Descending aortic flow was also sharply increased (mean 930 ml/min/kg; normal 184 +/- 20), as was placental flow (mean 480 ml/min/kg, normal 110 +/- 26). High-velocity arterial flow signals were also found within the tumor. In one fetus studied serially, placental thickness and tumor diameter increased rapidly; placental flow as a percentage of descending aortic flow decreased, indicating a further increase of flow to the tumor. These abnormal hemodynamic changes were reversed after the fetuss teratoma was surgically removed. We conclude that the sacrococcygeal teratoma acts as a large arteriovenous fistula, which causes high-output cardiac failure. Surgical removal of the teratoma in a previable fetus with such hemodynamic findings may prove to be the most effective treatment.

Effects of increasing afterload on left ventricular output in fetal lambs

Fetal ventricular performance has been considered limited because ventricular output does not increase with rapid volume expansion above mean left atrial pressures (mLAPs) of 5–7 mm Hg. To explore relations between preload, afterload, and stroke volume (SV) in the fetal left ventricle, we instrumented 126–129 days gestation fetal lambs with ascending aortic electromagnetic flow transducers, vascular catheters, and inflatable occluders around the aortic isthmus (n=8) or descending aorta (n=7). At 24–48 hours after surgery, blood was withdrawn or infused to reach various mLAPs. The aorta was then slowly occluded as aortic flow and mean arterial pressure (MAP) were measured continuously. Isthmus constriction produced linear decreases in SV as MAP increased; mLAP was unchanged. Descending aortic constriction produced no decrease in SV until high MAPs were reached. SV decreased as MAP increased further, and mLAP rose significantly. The curve relating mLAP and SV before constriction showed little increase in SV above mLAPs of 5–7 mm Hg; however, when curves were derived relating SV and mLAP at relatively constant MAPs, SV continued to increase even above an mLAP of 8–10 mm Hg. Our studies indicate that the fetal left ventricle responds to progressive increases in mLAP to at least 10 mm Hg. The lack of increase in SV above an mLAP of 5–7 mm Hg with rapid volume expansion is related to the concomitant increase in MAP and afterload. {Circulation Research 1989;65:127–134)

Interventional neuroradiological management of vein of Galen malformations in the neonate.

Since 1978, the authors have seen 14 neonates with vein of Galen malformations who were born with severe congestive heart failure. The 5 infants treated before 1983 underwent craniotomy and clipping of feeding vessels; all died in the perioperative period. Since 1983, 8 neonates have been treated with combined arterial and venous interventional neuroradiological techniques; 6 infants survived. Two-dimensional echocardiography, color Doppler flow imaging, and pulsed Doppler ultrasound were used to assess blood flow within the malformation before and after staged transluminal embolic procedures were performed. The results of the diagnostic studies and the clinical status of the infants were used to evaluate the success of embolic therapy and the need for further neuroradiological intervention.

Determination ef ventricular volumes in human fetal hearts by two-dimensional echocardiography

In conclusion, ventricular volume calculation from 2DE is feasible in the human fetus and improves the ability to calculate fetal ventricular size and ejection fraction. The right ventricle is clearly dominant at midgestation, but approaches left ventricular size at term. Calculation of the ventricular output from 2DE volume measurements is an accurate alternative to Doppler measurements.

Assessment of Flow Events at the Ductus VenosusInferior Vena Cava Junction and at the Foramen Ovale in Fetal Sheep by Use of Multimodal Ultrasound

BACKGROUND Previous techniques for the study of the fetal circulation did not permit assessment of phasic events associated with the cardiac cycle. We used multimodal ultrasound techniques to examine flow events that occur in the major veins and across the foramen ovale in the circulation of the fetal lamb. METHODS AND RESULTS We studied eight fetal lambs instrumented with catheters in the superior and inferior venae cavae and a peripheral umbilical vein and performed ultrasound studies that included M-mode and two-dimensional imaging, pulsed and Doppler color flow ultrasound, and contrast echocardiography to evaluate flow in the ductus venosus, in both venae cavae, and through the foramen ovale. Two blood streams of different flow velocities were identified within the cephalic portion of the inferior vena cava. The stream that originated from the narrowed ductus venosus had a higher velocity than that from the caudal inferior vena cava (mean velocity, 57 +/- 13 versus 16 +/- 3 cm/s; P < .0002). Facilitated by the eustachian valve and the septum primum, the ductus venosus stream preferentially passed through the foramen ovale to the left atrium. This flow occurred during most of the cardiac cycle, except for 19.6 +/- 2.3% of the cycle when the foramen ovale was closed during atrial contraction. Superior vena cava flow passed almost exclusively into the right atrium and tricuspid valve; a small amount that was refluxed from the right atrium into the inferior vena cava subsequently passed through the foramen into the left atrium. CONCLUSIONS Visualization of fetal circulatory streaming at the venous sites by ultrasound techniques aids in understanding the function of the fetal circulation and may be helpful in detecting the human fetus that is hemodynamically compromised.

Doubly committed subarterial ventricular septal defects: Echocardiographic features and surgical implications

Doubly committed subarterial (supracristal, subpulmonary) ventricular septal defects are often complicated by aortic regurgitation resulting from aortic valve herniation into the defect. The clinical, echocardiographic and catheterization findings in 48 patients aged 0.3 to 46.4 years (median 9.5) with a doubly committed subarterial ventricular septal defect were reviewed. Aortic valve herniation was present in 38 (79%) and 55% of these had aortic regurgitation. The prevalence of both findings increased gradually with advancing age. The defect was closed surgically in 41 patients. Surgery during the first 2 years of life (median 0.4 year) was performed in 13 patients (group I), mainly because of a large shunt with a pulmonary to systemic flow ratio (Qp/Qs) 3.8 +/- 1.4 (mean +/- SD). Aortic regurgitation was present preoperatively in two patients (15%), persisted postoperatively in one patient and did not develop in any after repair (median duration of follow-up 2.3 years, range 0.1 to 7.4). In the other 28 patients (group II) surgery was performed between 4.8 and 46.4 years of age (median 11.5). These patients were generally less symptomatic and had a smaller shunt (Qp/Qs 1.5 +/- 0.5, p less than 0.001). Preoperative aortic regurgitation was present in 18 (64%). It persisted in 15 postoperatively, but in 13 of these it had diminished. Two-dimensional echocardiography in multiple views identified the site of the ventricular septal defect in all patients. Serial echocardiographic examinations demonstrated the progressive nature of aortic valve herniation, the partial occlusion of the defect by the herniated sinus and the development of aortic regurgitation. These findings suggest that timely surgical closure of these defects may prevent aortic regurgitation.