Technological advances to extend the echocardiographic imaging of pediatric patients.

Recent technological advances provide significant improvement in the quality of imaging for the acoustically challenged pediatric patient. Although tissue harmonics allow better imaging of the larger or postoperative patient, high-frequency transducers tend to optimize imaging in smaller patients. Miniaturization of transducers and ultrasound systems has lead to the innovative utilization of previously unavailable acoustic windows in a wider variety of settings. Each improvement advances the technology closer to the goal of providing optimal cardiac imaging in nearly all patients under virtually all circumstances.

Complete follow-up echocardiograms are needed to detect stenosis of normally connecting pulmonary veins.

Reimbursement for limited echocardiograms focusing on known pathology rather than complete studies has recently received widespread attention. Few data are available to determine if these limited examinations provide enough information to adequately evaluate many forms of congenital heart disease. Stenosis of normally connecting pulmonary veins is a congenital or acquired cardiac anomaly that is difficult to diagnose clinically and may be detectable only by echocardiography. To evaluate the yield of complete versus limited echocardiograms for detecting the presence and development of stenosis in pulmonary veins with anatomically normal connections, the cardiology database was searched for all patients with this diagnosis presenting between June 1990 and January 2000. Charts were reviewed for demographic data, associated defects, surgeries, and outcomes. Angiograms and echocardiograms were reviewed for location and severity of pulmonary vein stenosis. A pulsed-wave Doppler signal of > 1.6 mm/sec with loss of phasic flow was used to define stenosis. Eighteen patients were identified and ranged in age at first evaluation from 1 day to 17 years (median 15 days). All 18 patients had associated cardiac anomalies, and 4 (22%) of 18 had Trisomy 21. Pulmonary vein stenosis was detected on the initial evaluation in 5 patients, detected 8 +/- 5 months after the initial echocardiogram in 11 patients, and missed by echocardiography in 2 patients who were diagnosed by cardiac catheterization. The initial echocardiograms were complete, with pulsed-Doppler sampling of all four pulmonary veins in 17 of 18 patients. Of the 12 patients who had echocardiographic evidence of late stenosis, 10 had 17 limited interim studies prior to eventually having a complete diagnostic follow-up study. Of the two patients in whom the diagnosis was missed by echocardiography, one initial study was technically inadequate (17-year-old) and one had only limited interim studies after the initial echocardiogram. Of the 9 patients in whom repair of the pulmonary vein stenosis was attempted, 3 had no residual obstruction and 6 had progressive stenosis (three deaths). Of the remaining nine patients who had no intervention for their pulmonary venous stenosis, four have died from progressive pulmonary hypertension. Stenosis of normally connecting pulmonary veins is an uncommon lesion that has a significant impact on clinical outcome. The stenoses might be undetectable on limited echocardiograms that focus on evaluating only specified pathology. Complete follow-up examinations might be warranted to diagnose this lesion. This may be an important consideration when formulating reimbursement policies.

Pharmacological therapy for patients with Kawasaki disease.

Kawasaki disease is a systemic vasculitis of unknown aetiology that has been reported worldwide since its initial description in Japanese children. The most significant sequelae of acute Kawasaki disease are related to the inflammation of small to medium sized arteries and, in particular, the development of coronary artery aneurysms. Because the aetiology is unknown, pharmacological therapy is nonspecific and directed towards modulation of the inflammatory response and inhibition of platelet activation with the aim of preventing coronary artery aneurysms. In the US, the recommended treatment for Kawasaki disease in the acute phase is a single, high dose of intravenous gammaglobulin (2 g/kg) and high dose aspirin (80 to 100 mg/kg/day). Use of this regimen has resulted in a significant decrease in the incidence of coronary artery abnormalities. Although the American Heart Association currently recommends high dose aspirin, moderate doses are used in Japan and the optimal dose of aspirin is not known. There has been renewed interest in the use of corticosteroids in the treatment of acute Kawasaki disease: however, their precise role remains unclear. Newer antiplatelet agents have also shown some promise in the treatment of patients with coronary artery aneurysms. Long term pharmacological therapy consists primarily of anticoagulation in patients with persistent coronary artery abnormalities. In this review, current recommendations for pharmacological therapy in Kawasaki disease are reviewed and some of the controversies in management of this disease, including management of patients who do not respond to initial therapy and the role of corticosteroids in the acute setting, are outlined.

Intra-aortic balloon pumping in children with dilated cardiomyopathy as a bridge to transplantation.

Children with dilated cardiomyopathy awaiting transplantation who fail maximal pharmacologic therapy may benefit from intra-aortic balloon pumping. Between July 1993 and August 1999, a total of 4 children with dilated cardiomyopathy underwent pre-transplant balloon pumping for 6.0 +/- 5.8 (1 to 12) days. One child (pumped for 12 days) died awaiting transplant, and the remaining 3 were successfully transplanted. Intra-aortic balloon pumping timed precisely with M-mode echocardiographic markers offers a relatively simple and safe intermediate level of mechanical support for children with dilated cardiomyopathy who fail pharmacologic support.

In vitro evaluation of the effect of aortic compliance on pediatric intra-aortic balloon pumping.

OBJECTIVES: To evaluate the effect of aortic compliance on pediatric intra-aortic balloon pumping (IABP). DESIGN: In vitro study using a mechanical model of the pediatric left heart circulation. SETTING: Cardiovascular fluid dynamics research laboratory. SUBJECT: Pulsatile flow system simulating the pediatric left heart circulation and two different aortas with compliances comparable to those of the pediatric aorta (0.12 and 0.07 mL/mm Hg). INTERVENTIONS: Measurements were made at a baseline peak aortic flow of 4 L/min, at simulated shock (1.7 L/min), and with 1:1 IABP (rates, 130 and 150 bpm; balloon volumes, 2.5 and 5.0 mL). MEASUREMENTS AND MAIN RESULTS: Peak flow rates were measured in the ascending aorta, coronary arterial system, and brachiocephalic arterial systems. Aortic pressure was measured in the ascending aorta. For both aortas (0.12 and 0.07 mL/mm Hg), IABP resulted in diastolic augmentation (38 +/- 8 and 43 +/- 16 mm Hg) and afterload reduction (4 +/- 2 and 6 +/- 3 mm Hg). For both aortas, compared to shock, IABP resulted in significant increases in coronary arterial and brachiocephalic arterial flow and aortic pressure for both aortas. Aortic flow significantly increased only in the less-compliant aorta. CONCLUSIONS: In a laboratory model of pediatric left heart circulation, IABP results in diastolic augmentation, afterload reduction, and improved hemodynamics, even in aortas of greater compliance.

Quantitative assessment of ventricular function in children with single ventricles using the Doppler myocardial performance index.

Assessment of ventricular function in patients with functionally single ventricles and unusual ventricular geometry is difficult. The Doppler myocardial performance index (MPI) may provide a method of assessing function in these patients. The purposes of this study were to compare the MPI in normal children and in children with a functionally single ventricle, and to compare the MPI in patients with single ventricles before and after bidirectional cavopulmonary anastamosis (BCPA). Echocardiograms of all patients who underwent BCPA between January 1994 and December 1998 were reviewed before and after surgical palliation. Age-matched normal subjects (n = 30) served as controls. The MPI was calculated from Doppler tracings of ventricular inflow and outflow. Of the 60 patients with single ventricles who underwent BCPA, 41 had adequate preoperative Doppler studies to allow calculation of the MPI, and 21 of 41 had adequate studies before and after BCPA. The MPI was higher in patients with single ventricles than in normal controls (0.67 +/- 0.14 vs 0.32 +/- 0.10, p < 0.001). There was no significant difference in the MPI in patients with single ventricles before and after surgery (0.70 +/- 0.16 vs 0.66 +/- 0.15). However, patients who had a BCPA at < 1 year of age had a significant decrease in the MPI after surgery (0.71 +/- 0.10 vs 0.61 +/- 0.11, p = 0.01). Compared with controls, the MPI was significantly higher in patients with single ventricles suggesting an altered hemodynamic state consistent with decreased ventricular function. The MPI decreased in patients who underwent BCPA at < 1 year of age, suggesting an improvement in ventricular function. The MPI provides an objective method of assessing and following ventricular function in patients with single ventricles that is independent of ventricular geometry.

Can Doppler systemic venous flow indices predict central venous pressure in children?

Tricuspid valve, superior vena cava (SVC), and hepatic vein Doppler patterns may be abnormal in right heart anomalies and have been used to predict high central venous pressure (CVP) in adults. The purpose of this study was to evaluate the relationship of these systemic venous flow indices to CVP in children. Children undergoing cardiac catheterization were studied prospectively using simultaneous recordings of mean CVP with pulsed-Doppler tracings of SVC, hepatic vein, and tricuspid valve flow. Systemic venous Doppler measurements included peak velocities and velocity time integrals for ventricular systole (S), ventricular diastole (D), and ventricular systole (B), and atrial systole (A). Tricuspid inflow Doppler E and A waves were recorded also. Patients with significant tricuspid stenosis or regurgitation, systemic venous obstruction, and nonsinus rhythm were excluded. The 42 patients ranged in age from 0.2 to 21.0 years and in weight from 3.0 to 68.0 kg. Mean CVPs ranged from 1 to 17 mmHg. Catheterization indications included hemodynamic evaluation (25 patients), transplant biopsy, (11 patients), and interventional procedures (6 patients). No SVC or tricuspid valve Doppler measurement correlated with CVP. Hepatic vein peak D, peak B, and peak A significantly correlated with CVP (r = 0.34 - 0.55; P < 0.05, linear regression). For all correlations, the r values were low with significant overlap among patients. Thus, in children, only hepatic vein peak velocities correlate with CVP. Because of the low r values and significant overlap among patients, the currently used Doppler indices have a low sensitivity for predicting CVP in this age group.

Usefulness of the preoperative tricuspid/mitral valve ratio for predicting outcome in pulmonary atresia with intact ventricular septum.

Although tricuspid valve z-scores have been used to predict outcome in pulmonary atresia with intact ventricular septum, they are statistically generated from local populations, and widespread generalization may not be appropriate. To determine if there are echocardiographic predictors of outcome that can be universally used, the records of all infants with this diagnosis since 1988 were reviewed for age, weight, type of surgery, and outcome. Preoperative and follow-up echocardiograms were reviewed for valve diameter and z-scores, and valve ratios were calculated. Thirty-six patients were divided into 2 groups: group 1 included 23 infants who had a successful biventricular repair; group 2 included the remaining 13 infants who did not have a successful repair. Preoperatively, both groups had similar ages, pulmonary, aortic, and mitral z-scores, and pulmonary/aortic ratios, but the patients in group 2 had significantly lower weight (3.5 +/- 0.6 vs 2.9 +/- 0.5 kg), tricuspid z-scores (-0.7 +/- 1.5 vs -2.3 +/- 1.2), and tricuspid/mitral ratios (0.8 +/- 0.2 vs 0.5 +/- 0.1). At similar follow-up, both groups of patients had similar weight, aortic and mitral z-scores, and pulmonary/aortic ratios, but group 2 infants had significantly lower pulmonary and tricuspid z-scores and tricuspid/mitral ratios. Compared with the preoperative echocardiograms, group 1 had significant increases only in pulmonary z-scores, and pulmonary/aortic and tricuspid/mitral ratios. Group 2 had no significant change in any echocardiographic variable. The tricuspid/mitral ratio was >0.5 in all group 1 infants, and in 6 of 13 group 2 infants (2 sepsis deaths, 4 palliations). Compared with a tricuspid valve z-score >-3, a tricuspid/mitral ratio >0.5 was a better predictor of biventricular repair. Thus, infants who have a successful biventricular repair have significantly greater preoperative weight, tricuspid valve z-scores, and tricuspid/mitral valve ratios. A tricuspid/mitral ratio >0.5 was the best predictor of a biventricular repair.

Aortic input impedance in infants and children.

Flow and pressure measurements were performed in the ascending aortas of six pediatric patients ranging in age from 1 to 4 yr and in weight from 7.2 to 16.4 kg. From these measurements, input impedance was calculated. It was found that total vascular resistance decreased with increasing patient weight and was approximately one to three times higher than those of adults. Conductance per unit weight was relatively constant but was approximately three times higher than for adults. Strong inertial character was observed in the impedance of four of the six patients. Among a three-element and two four-element lumped-parameter models, the model with characteristic aortic resistor (R(c)) and inertance in series followed by parallel peripheral resistor (R(p)) and compliance fitted the data best. R(p) decreased with increasing patient weight and was one to three times higher than in adults, and R(c) decreased with increasing patient weight and was 2 to 15 times higher. The R(p)-to-R(c) ratio differed significantly between infants and children vs. adults. The results suggested that R(p) developed more rapidly with patient weight than did R(c). Compliance values increased with increasing patient weight and were 3 to 16 times lower than adult values.

What is the yield of screening echocardiography in pediatric syncope?

OBJECTIVE: To determine the yield of screening echocardiography in the evaluation of pediatric syncope. DESIGN: All patients diagnosed with syncope from January 1993 to January 1999 were identified and their records were reviewed for age, weight, sex, year of presentation, personal and family history, physical examination, and cardiac diagnostic testing. Cardiac defects were identified by reviewing echocardiograms and reports. RESULTS: The 480 patients (268 females) ranged in age from 1.5 to 18.0 years old and ranged in weight from 10.3 to 113.6 kg. Final diagnoses included noncardiac causes in 458, long QT syndrome in 14, arrhythmias in 6, and cardiomyopathy in 2. An abnormal history, physical examination, or electrocardiogram identified 21 of the 22 patients with a cardiac cause of syncope. Of the 322 (67%) echocardiograms performed, abnormalities were detected in 37. These abnormalities included 26 minor valve anomalies, 7 hemodynamically insignificant shunt lesions, 2 mildly decreased left ventricular shortening fractions, and 2 cardiomyopathies. Only the 2 cardiomyopathies were considered to be potential causes of syncope, and in both cases, the electrocardiogram was markedly abnormal. A similar percentage of echocardiograms were ordered during the first and last 3 years of the study (61% vs 71%). CONCLUSION: History, physical examination, and electrocardiography provide a screening protocol that allows the identification of a cardiac cause of syncope in the overwhelming majority of pediatric patients. In the absence of a positive screen result, the echocardiogram does not contribute to the evaluation of syncope in children. We speculate that primary care providers and pediatric cardiologists continue to use echocardiography because of the paucity of data regarding its value in pediatric syncope. However, this study shows little benefit of screening echocardiography and should discourage its routine use.

An unusual variant of total anomalous pulmonary venous connection with varices and multiple drainage sites.

Total anomalous pulmonary venous connection (TAPVC) is an uncommon cardiac anomaly that has also rarely been associated with esophageal atresia. We report an unusual case of esophageal atresia with TAPVC with several varices and multiple drainage sites into the superior vena cava and portal vein.

Spectrum and influence of hypoplasia of the left heart in neonatal aortic coarctation.

Obstruction of the left ventricular outflow tract may be associated with hypoplasia of the left heart, which importantly influences the options for treatment. Although the influence of the size of the left heart on the outcome for critical aortic stenosis has been described, less is known about the spectrum of such hypoplasia seen with neonatal aortic coarctation, and how this influences outcome. To determine, first, the spectrum and influence of hypoplasia of the left heart in neonatal coarctation, second, if the previously described critical values for adequacy of the left heart in neonates with critical aortic stenosis are applicable to neonates with coarctation, and, third, if any of the variables or associated abnormalities are risk factors for recoarctation, we studied 63 neonates who underwent repair of coarctation. From the initial echocardiogram, we measured multiple structures in the left heart, and calculated a score for adequacy as has been done for critical aortic stenosis. The sizes were compared to previously reported minimal values. We then analyzed the influence of the variables and the associated anomalies on outcome. There were no deaths. There was a broad spectrum of sizes that did not correlate with the need for re-intervention. The calculated score for adequacy would have predicted survival in only 56% of the patients, and 73% of the neonates had at least one parameter measured in the left heart below the previously reported minimal values. There is, therefore, a broad spectrum of sizes for the left heart in neonates with aortic coarctation that is not predictive of outcome. Minimal sizes, and the score for adequacy used for critical aortic stenosis, are not applicable to neonates with coarctation.

Are screening echocardiograms warranted for neonates with meningomyelocele?

OBJECTIVE: To evaluate the incidence and types of congenital heart defects associated with meningomyelocele. DESIGN: All neonates who underwent meningomyelocele repair and had a perioperative echocardiogram from July 1990 to October 1998 were studied. Medical records were reviewed for age, weight, clinical cardiac examination results, meningomyelocele location, and associated noncardiac defects. Heart defects were identified from reviewing echocardiographic reports and videotapes. RESULTS: At meningomyelocele surgery, the 105 patients (53 female; 52 male) ranged in age from 1 to 20 days and in weight from 0.6 to 4.1 kg. Congenital heart disease was detected in 39 patients (37%). A secundum atrial septal defect was the most common defect (24%). A ventricular septal defect was found in 10 patients, 2 patients had anomalous pulmonary venous return, and 1 each had tetralogy of Fallot, bicuspid aortic valve, coarctation, and hypoplastic left heart syndrome. A patent ductus arteriosus and patent foramen ovale were not considered abnormal in these neonates. The cardiac examination was abnormal in only 5 of the 39 patients with heart defects (sensitivity = 13%). The presence of associated noncardiac defects (in addition to meningomyelocele) and location of the meningomyelocele (cervicothoracic vs lumbar) did not affect the incidence of heart disease. Of the patients with heart defects, girls were more frequently affected (25 of 39 vs 14 of 39, P<.05). CONCLUSIONS: Congenital heart defects are common in neonates, especially girls, with meningomyelocele and are unrelated to meningomyelocele location or associated noncardiac defects. Because the clinical examination is insensitive for detecting heart defects in this group, screening echocardiograms are warranted. This information has important implications for ventriculoatrial shunting, urinary tract instrumentation (antibiotic prophylaxis), and neurosurgical procedures (venous air embolism).

Influence of left ventricular cavity size on interventricular shunt timing and outcome in neonates with coarctation of the aorta and ventricular septal defect.

In this study, we reviewed the records and echocardiograms of 39 consecutive patients with coarctation of the aorta and ventricular septal defect who underwent neonatal coarctation repair to examine the influence of left heart size on ventricular shunting and outcome. We found smaller left heart structures (initial mitral and aortic annular diameters) to be associated with diastolic interventricular shunting and to be predictive of the development of mitral or aortic and/or subaortic stenosis.

Pulmonary vein stenosis with normal connection: associated cardiac abnormalities and variable outcome.

BACKGROUND: Pulmonary vein (PV) stenosis with anatomically normal connection is considered rare, unresponsive to treatment, progressive, and usually fatal. METHODS: We reviewed the records of 13 children with this diagnosis at our center since 1990. RESULTS: The number of stenosed PVs ranged from all PVs (n = 5); three PVs (n = 1); two PVs (n = 5); and one PV (n = 2). All patients had associated congenital cardiac abnormalities. Operation on PV stenosis was attempted in 7 patients (54%), 2 of whom have done well and 5 of whom have not. Two patients underwent heart transplantation for inoperable associated cardiac lesions. Significantly more patients with three or four stenosed PVs died (83%) compared with patients with one or two stenosed PVs (0%). CONCLUSIONS: (1) Pulmonary vein stenosis with anatomically normal connection is associated with other congenital cardiac abnormalities, (2) presentation and outcome are contingent on the number of stenosed PVs, (3) surgical palliation may be helpful in some patients, and (4) heart transplantation for inoperable associated cardiac abnormalities may be an option in patients with only one or two stenosed PVs.