Nitric oxide in the evaluation of congenital heart disease with pulmonary hypertension: factors related to nitric oxide response

Inhaled nitric oxide (NO) has been used in the preoperative evaluation of patients with congenital heart disease and pulmonary hypertension. The purpose of this study was to characterize responses in pulmonary vascular resistance (PVR) to oxygen and increasing doses of NO during cardiac catheterization and to determine if any related factors affect the response of the pulmonary vascular bed to NO. A prospective analysis of 42 patients (median age, 3.0 years) with congenital heart disease and pulmonary hypertension who underwent NO testing was performed. Systemic vascular resistance (SVR) and PVR were assessed in room air, 100% oxygen, and oxygen plus 20, 40, and 80 parts per million (ppm) NO. Changes in pulmonary artery pressure, PVR, and SVR were assessed. The response to NO was then correlated to individual patient's age, gender, type of heart defect, the presence of trisomy 21, and baseline PVR/SVR. There was a greater decrease in PVR and PVR/SVR with 20 ppm NO than with oxygen alone. There was no additional decrease at 40 or 80 ppm NO. There was no correlation between age, gender, type of congenital heart disease, and baseline PVR/SVR ratio with the degree of response to NO. Patients with trisomy 21 had less of a response to NO (p = 0.017) than patients without trisomy 21. There is no difference in determining PVR response with doses of NO beyond 20 ppm during cardiac catheterization. Age, gender, and baseline PVR/SVR ratio are not associated with responsiveness to NO. Patients with trisomy 21 may be less responsive to NO.

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.

The impact of fetal echocardiography

Fetal echocardiography has impacted the fetus with congenital heart disease in many important ways. Advances in fetal echocardiography have allowed for more accurate and earlier detection of cardiac abnormalities. In turn, the prenatal diagnosis of cardiac abnormalities has improved the care and outcome of selected fetuses with severe cardiac malformations or arrhythmias. Fetal echocardiography has improved the understanding of the development and evolution of congenital heart disease in utero, and it may serve a role in identifying candidates for prenatal intervention. The prenatal diagnosis of congenital heart disease has allowed for better counseling and preparation of families regarding the anticipated prenatal development of the fetus as well as the expected postnatal management plans and prognosis. This article reviews the impact of fetal echocardiography in these and other areas.

Growth of an atrial septal defect: missing the window for transcatheter closure

We describe a patient diagnosed with a small atrial septal defect (3-4 mm) that had grown to 24 mm in diameter over a six-year period. Timing of transcatheter intervention may be affected by growth of the atrial septal defect and this reports the first case of an atrial septal defect outgrowing the possibility of transcatheter closure.

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.

Use of tissue harmonic imaging in pediatric echocardiography

Tissue harmonic imaging improves the quality of images in adults with poor acoustic windows, but its utility in children has yet to be evaluated. The use of fundamental and harmonic imaging were compared in 70 children with poor echocardiographic windows. Scores were higher for harmonic in comparison to fundamental imaging for all views. Harmonic imaging improves the visualization of cardiac structures over fundamental imaging in children with poor echocardiographic windows.

Aneurysmal dilatation of the ductus arteriosus in a neonate

Fetal ultrasound provides the capacity for early detection of a variety of congenital heart diseases. We report a case of aneurysmal dilatation of a patent ductus arteriosus detected in utero and subsequently confirmed by transthoracic echocardiography in the neonatal period. Prompt recognition of the ductus aneurysm with resultant surgical ligation may have averted potentially serious complications from this condition.

Coronary artery fistula. Management and intermediate-term outcome after transcatheter coil occlusion

During the last 2 decades, transcatheter occlusion of coronary artery fistulae has developed into a safe and effective therapy for children. This procedure avoids the need for open surgical repair and the attendant complications of cardiopulmonary bypass and median sternotomy. The long-term outcome in patients after transcatheter occlusion remains unknown. We describe the intermediate-term progress of 4 such patients after coil occlusion of coronary artery fistulae. Persistent coronary artery dilatation was present in all patients reviewed, as late as 4 years after occlusion.

Accuracy of prenatal echocardiographic diagnosis and prognosis of fetuses with conotruncal anomalies

OBJECTIVES

The purpose of the study was to determine the accuracy of the prenatal echocardiographic diagnosis and prognosis of fetuses with conotruncal anomalies.

BACKGROUND

The accuracy of prenatal echocardiographic diagnoses of cardiac lesions has been reported, but no previous reports specifically address fetal conotruncal anomalies.

METHODS

Medical records of 61 fetuses, in which a fetal diagnosis of a conotruncal anomaly was made, were reviewed. Disease entities included were tetralogy of Fallot (TOF), double outlet right ventricle (DORV), transposition of the great arteries (TGA), and truncus arteriosus (TA).

RESULTS

Fetal diagnosis was established at a median of 24.5 weeks' gestation. Termination of pregnancy was chosen in 31% (19/61) of cases. Postnatal assessment of the diagnosis was not obtained in 12 cases. Excluding two sets of conjoined twins, accurate prenatal diagnosis including definition of the great artery orientation was achieved in 36 of 47 cases (77%). Seven of 17 fetuses with DORV anatomy, of which 6 were thought to have a subpulmonary ventricular septal defect (VSD), had incorrect prenatal assessment of the great artery relationships. One fetus thought to show features of TA had aortic atresia with VSD and normal-sized left ventricle. Of the 42 pregnancies that continued, 15 had major extracardiac malformations and/or chromosomal abnormalities of which one died in utero with trisomy-13 and TA. A further nine died within the neonatal period. Among the 27 fetuses without a documented chromosomal or major extracardiac anomaly, 13 (48%) died. Overall, the survival rate beyond 28 days of life was 52% (22/42). In contrast, 75% (6/8) of fetuses with TOF, excluding the absent pulmonary valve syndrome, survived.

CONCLUSIONS

Conotruncal anomalies can be diagnosed by prenatal echocardiography with a high degree of accuracy. Defining the exact spatial relationship of the great arteries is problematic in some fetuses. The overall prognosis for fetuses with a conotruncal anomaly is poor, with the exception of uncomplicated TOF.

Resection of subaortic stenosis; can a more aggressive approach be justified?

OBJECTIVES

Discrete subaortic stenosis causes left ventricular outflow tract (LVOT) obstruction and often produces aortic regurgitation (AR) which alone may precipitate surgical intervention. Conventional resection relieves the obstruction, but the recurrence rate is high, and the AR is little changed as the thick fibrous membrane which extends onto the valve leaflets remains. We studied whether an aggressive surgical approach could reduce both the severity of AR and rate of recurrence of obstruction associated with discrete subaortic stenosis, and whether this aggressive approach could be justified.

METHODS

Between June 1992 and April 1996, 37 patients aged 0.5-35 years (median 7.5) underwent resection of a discrete subaortic membrane. Ten underwent re-operation for recurrent obstruction and eight followed previous ventricular septal defect closure. LVOT gradient was measured using the modified Bernoulli equation and AR was graded on a scale of 0-4 (0 = none, 4 = severe). Postoperative assessment was performed early (<7 days) and at mid-term (27.0 months; range 2-59 months).

RESULTS

There was significant improvement in AR from mild/moderate to none/trivial (P = 0.019) immediately postoperatively and LVOT gradient from 66.9+/-30.4 to 15.1+/-12.2 mmHg (P < 0.0001). By stepwise logistic regression preoperative gradient correlated significantly with postoperative mild/moderate AR (P = 0.015) and LVOT gradient (P = 0.0036). Preoperative mild/moderate AR also correlated with postoperative mild/moderate AR (P = 0.034). Five patients developed complete heart block, four undergoing reoperation for recurrent obstruction, and one preoperatively had right bundle branch block from previous ventricular septal defect repair. At mid-term follow-up there was no increase in AR or LVOT gradient (14.8+/-12.8 mmHg). Early post-operative AR was the strongest predictor of late mild/moderate AR (P = 0.02). Early post-operative gradient was a weaker predictor (P = 0.04). Pre-operative and early post-operative gradient were significant predictors of late gradient (P = 0.0038; <0.0001, respectively). No patient required reoperation for recurrent obstruction; one underwent late aortic valve replacement for severe AR.

CONCLUSIONS

An aggressive surgical approach to discrete subaortic stenosis produces excellent relief of obstruction and frees the valve leaflets, significantly reducing associated AR at early and mid-term follow-up with low morbidity for primary operation. Long-term follow-up is required to confirm whether this early benefit is maintained.

Echocardiographic hemodynamic and morphometric predictors of survival after two-ventricle repair in infants with critical aortic stenosis

OBJECTIVES

The purpose of this study was to identify echocardiographic hemodynamic and morphometric factors that would predict which infants with critical aortic stenosis could undergo relief of left ventricular outflow obstruction as opposed to the Norwood procedure.

BACKGROUND

Echocardiographic predictors of survival in infants with critical aortic stenosis after two-ventricle repair have been mainly limited to morphometric factors, which have limitations. Echocardiographic hemodynamic predictors of survival in these patients have not previously been studied.

METHODS

Doppler color flow mapping and pulsed Doppler techniques were used to obtain hemodynamic measurements of flow in the ascending, transverse and descending aorta, the ductus arteriosus, and across the aortic and mitral valves in infants with critical aortic stenosis. Morphometric measurements of the left heart structures were obtained, and comparisons were made between survivors and nonsurvivors for the hemodynamic and morphometric factors.

RESULTS

Twenty-eight infants (mean age 1 +/- .6 days, mean weight 3.6 +/- .6 kg) with critical aortic stenosis were evaluated. Nineteen had a two-ventricle repair initially attempted, and nine had a Norwood operation. Among the patients with a two-ventricle repair, the hemodynamic factors associated with survival after two-ventricle repair included predominant or total antegrade flow in the ascending (p < 0.01) and transverse aorta (p < 0.05). Aortic valve gradient, mitral valve inflow and direction of flow in the ductus arteriosus and descending aorta were unrelated to outcome. The morphometric factors associated with survival after two-ventricle repair included the indexed aortic annulus (p < 0.0002), aortic root (p < 0.003), ascending aorta (p < 0.008) and left ventricular long-axis length (p < 0.01). Left ventricular volume, mass, ejection fraction and mitral valve area were not related to outcome after two-ventricle repair.

CONCLUSIONS

In infants with critical aortic stenosis, predominant or total antegrade flow in the ascending and transverse aorta was associated with survival after two-ventricle repair. Determination of a one- versus two-ventricle repair remains a complex issue in infants with critical aortic stenosis. In addition to established morphometric predictors, hemodynamic information on the direction of flow in the aorta may help to define candidates for the Norwood operation.

Balloon pulmonary valvuloplasty and stent implantation. For peripheral pulmonary artery stenosis in Alagille syndrome

We report the case of a patient with Alagille syndrome and severe pulmonary valve and bilateral pulmonary artery branch stenosis. In this patient, transcatheter balloon pulmonary valvuloplasty combined with bilateral pulmonary artery angioplasty and stent placement provided excellent immediate results and long-term improvement.

Echocardiographic predictors of poor outcome in infants with hypertrophic cardiomyopathy

Although hypertrophic cardiomyopathy (HC) is readily diagnosed by echocardiography in infants with isolated ventricular hypertrophy, echocardiographic predictors of outcome have not been described in this age group. To identify echocardiographic predictors of poor outcome of infants with HC, we reviewed medical records and echocardiograms of all 19 patients with HC aged <1 year seen at the University of California, San Francisco, from January 1981 through December 1995. Thickness of the ventricular septum and the left ventricular (LV) posterior wall, ventricular septum/LV posterior wall ratio, LV mass, LV volume, LV mass/volume ratio, LV ejection fraction, and right ventricular anterior wall thickness were measured. The median age at diagnosis was 1 day; 11 were boys and 8 were girls. Within 1 year after birth, 10 patients died: the other 9 patients have survived to > 12 months of age. At the initial postnatal examination, the Z value for LV posterior wall was larger (median, 5.2 vs 1.3, p <0.04) and, consequently, the ventricular septum/LV posterior wall ratio was lower (1.6 vs 2.3, p <0.04) in nonsurvivors than in survivors. In serial studies, the Z value for both the ventricular septum and the LV posterior wall thickness increased in nonsurvivors, but decreased in survivors. Nonsurvivors had intrinsic metabolic disease or Noonan syndrome. Survivors had classic HC or maternal diabetes. We conclude that, in infants with HC, early or progressive hypertrophy of the LV posterior wall is a predictor of poor outcome, regardless of associated disease.

Echocardiographic determinants of clinical course in infants with critical and severe pulmonary valve stenosis

OBJECTIVES

The purposes of this study were to determine the growth pattern of the pulmonary valve (PV) annulus and right heart structures in patients with critical and severe pulmonary stenosis (PS) after balloon dilation, and to determine any morphometric or hemodynamic differences between cyanotic infants with critical PS and asymptomatic infants with severe PS that may account for their varied clinical presentations.

BACKGROUND

Growth of the PV annulus and right heart structures in patients with critical PS after balloon valvuloplasty has not clearly been defined. In addition, the anatomic and hemodynamic factors that determine whether an infant with severe PS will present with cyanosis or without symptoms are not well understood.

METHODS

Measurements of the PV annulus, tricuspid valve (TV) annulus and main, right and left pulmonary arteries were obtained from initial and follow-up echocardiograms, and Z values were calculated. Hemodynamic data and balloon pulmonary valvuloplasty techniques were reviewed. Right ventricular (RV) volumes were measured from angiograms.

RESULTS

Fourteen patients with critical PS (mean [+/- SD] age 0.21 +/- 0.37 months) and 20 patients with severe PS (mean age 2.6 +/- 2.9 months) were evaluated at presentation and at 32 +/- 33 and 42 +/- 32 months of follow-up, respectively. Balloon pulmonary valvuloplasty was successful in 64% of patients with critical PS and in 90% of patients with severe PS. The PV, TV and pulmonary arteries increased in size after balloon pulmonary valvuloplasty in both groups at a rate that paralleled or exceeded the rate of somatic growth. The initial TV diameter and RV volume were smaller in patients with critical PS than in those with severe PS (p < 0.05 and p < 0.0008, respectively).

CONCLUSIONS

After balloon pulmonary valvuloplasty in infants with critical and severe PS, right heart structures increase in size at a rate that parallels or exceeds the rate of somatic growth. The primary morphometric differences between these groups are a smaller TV diameter and RV volume in infants with critical PS. This may contribute to increased right to left atrial shunting and account for the variations in clinical presentation.

Nitric oxide for the evaluation and treatment of pulmonary hypertension in congenital heart disease

The use of inhaled nitric oxide as a selective pulmonary vasodilator has expanded to include patients with congenital heart disease and pulmonary hypertension. The therapeutic and diagnostic roles of inhaled nitric oxide offer additional alternatives and benefits to these patients with pulmonary hypertension, particularly in the postoperative setting. This article reviews the background, mechanism of action, toxicities, and current clinical applications of inhaled nitric oxide in the child with congenital heart disease and pulmonary hypertension.

Pulmonary valve eccentricity in d-transposition of the great arteries and implications for the arterial switch operation

Neoaortic valve regurgitation is a known complication of the arterial switch operation for d-transposition. Its etiology and long-term effects are undetermined. Observations of pathologic specimens from 67 patients with d-transposition of the great arteries with or without ventricular septal defects demonstrated that the pulmonary valve leaflets had unequal cusp sizes leading to eccentric closure. The posterior cusp was usually the largest and was anatomically related to the membranous ventricular septum and the anterior leaflet of the mitral valve. The right cusp was usually the smallest. Differences in cusp sizes were unrelated to age at death, sex or presence of a ventricular septal defect. To determine if eccentricity could be clinically detected, the pulmonary valves in 24 sequential patients with d-transposition were studied echocardiographically and angiographically. Aortic valves were studied for comparison. All pulmonary valves demonstrated eccentric closure in the long-axis echo plane, posterior in 15 patients and anterior in 9. Only 1 aortic valve showed eccentricity. Angiographic findings correlated with echo findings. Sixteen patients underwent arterial switch operations; 3 died. Twelve had angiography at 1 year. Eleven had neoaortic valve regurgitation: 5 grade I, 4 grade II and 2 grade III.