Neonates with congenital heart disease, Part II: Congenital cardiac defects with increased pulmonary blood flow

Generally, cardiac lesions with increased pulmonary blood flow demonstrate cardiomegaly, increased pulmonary vascular markings, and pulmonary congestion on the chest x-ray. These findings occur as a result of the following: 1. A left-to-right shunt or mixing lesion in which excess volume of blood flow causes dilation of cardiac chambers, resulting in the appearance of cardiomegaly, and in which increased pulmonary artery blood flow causes increased pulmonary vascular markings 2. Obstruction of blood flow that produces pulmonary venous hypertension and resultant pulmonary edema The next article in this series will address cardiac lesions with decreased pulmonary blood flow.     

Inoperable pulmonary vascular disease in infants with congenital heart disease

BACKGROUND: Among 120 infants less than 12 months of age who had lung biopsy and autopsy, 20 were inoperable because of severe irreversible pulmonary vascular disease. METHODS: The infants were classified into three groups. Group 1 comprised 6 patients who showed complete obstruction of the small pulmonary arterial lumen and atrophy of the peripheral arterial media and who were considered to have absolute operative contraindications. Group 2 comprised 6 patients who had no pathologic findings of absolute operative contraindication and had an index of pulmonary vascular disease of more than 2.2. They were isolated as having advanced plexogenic pulmonary arteriopathy. Group 3 comprised 8 patients who had extremely thickened media of small pulmonary arteries, with abnormally thickened media extending into the small peripheral arteries characterized by extremely narrow lumina and medial thickness exceeding luminal diameter. RESULTS: Six of the 9 patients in whom operative repair was abandoned on the basis of preoperative or intraoperative lung biopsy are still alive. Of the 11 patients who underwent operation without biopsy, none survived. CONCLUSIONS: Preoperative or intraoperative lung biopsy and assessment of arteriopathy based on the above criteria are recommended in all patients in whom fatal pulmonary vascular disease is suspected.     

Reversed end-diastolic umbilical flow in a first-trimester fetus with congenital heart disease

Reversed end-diastolic umbilical artery velocities and a reduced chorionic sac were first seen at 10 weeks in a pregnancy subsequently showing a normal male karyotype on chorionic villi. Four weeks later Doppler studies demonstrated normal umbilical artery waveforms. At 20 weeks, ultrasound examination of the fetus revealed a mild pericardic effusion, hypoplastic righ heart with hypertrophic myocardium and a single umbilical artery, suggesting pulmonary atresia. After neonatal death, pathological studies confirmed pulmonary atresia. This case suggests that reversed end-diastolic umbilical flow in the first trimester may identify a subgroup of fetuses with a lethal abnormality (heart defect, severe intra-uterine retardation, aneuploidy or others).     

Recognition, understanding, and current management of cardiac lesions with decreased pulmonary blood flow

Congenital heart lesions can be classified according to hemodynamic characteristics related to pulmonary blood flow patterns: increased, normal, or decreased, lesions with decreased pulmonary blood flow characteristically present with cyanosis. This article briefly reviews differential diagnoses for the presenting sign of cyanosis. Additionally, this article provides a comprehensive overview of cardiac physiology of lesions with decreased pulmonary blood flow. This information provides a foundation of knowledge for the recognition of acute symptoms in the newborn period and an understanding of immediate stabilization and medical and surgical interventions related to each diagnosis.     

Endothelin receptor blockade prevents the rise in pulmonary vascular resistance after cardiopulmonary bypass in lambs with increased pulmonary blood flow

BACKGROUND: Children with increased pulmonary blood flow may experience morbidity as the result of increased pulmonary vascular resistance after operations in which cardiopulmonary bypass is used. Plasma levels of endothelin-1, a potent vasoactive substance implicated in pulmonary hypertension, are increased after cardiopulmonary bypass. OBJECTIVES: In a lamb model of increased pulmonary blood flow after in utero placement of an aortopulmonary shunt, we characterized the changes in pulmonary vascular resistance induced by hypothermic cardiopulmonary bypass and investigated the role of endothelin-1 and endothelin-A receptor activation in postbypass pulmonary hypertension. METHODS: In eleven 1-month-old lambs, the shunt was closed, and vascular pressures and blood flows were monitored. An infusion of a selective endothelin-A receptor blocker (PD 156707; 1.0 mg/kg/h) or drug vehicle (saline solution) was then begun 30 minutes before cardiopulmonary bypass and continued for 4 hours after bypass. The hemodynamic variables were monitored, and plasma endothelin-1 concentrations were determined before, during, and for 6 hours after cardiopulmonary bypass. RESULTS: After 90 minutes of hypothermic cardiopulmonary bypass, both pulmonary arterial pressure and pulmonary vascular resistance increased significantly in saline-treated lambs during the 6-hour study period (P <.05). In lambs pretreated with PD 156707, pulmonary arterial pressure and pulmonary vascular resistance decreased (P <. 05). After bypass, plasma endothelin-1 concentrations increased in all lambs; there was a positive correlation between postbypass pulmonary vascular resistance and plasma endothelin-1 concentrations (P <.05). CONCLUSIONS: This study suggests that endothelin-A receptor-induced pulmonary vasoconstriction mediates, in part, the rise in pulmonary vascular resistance after cardiopulmonary bypass. Endothelin-A receptor antagonists may decrease morbidity in children at risk for postbypass pulmonary hypertension. This potential therapy warrants further investigation.     

Neonates with congenital heart disease, Part IV: Total anomalous pulmonary venous return

Significant radiographic findings of TAPVR with unobstructed blood flow include the following: 1. Increased pulmonary vascular markings with dilated pulmonary arteries 2. Cardiomegaly 3. A "snowman" configuration of the heart, seen after pulmonary vascular resistance falls and blood flow through the lungs increases In TAPVR with obstructed blood flow, findings include the following: 1. A hazy, reticular, ground-glass appearance of the lung fields 2. Normal to small cardiac size.     

Growth and congenital heart disease

PURPOSE: To assess the efficacy of heparin in preventing the abrupt closure after coronary angioplasty in low risk patients for this phenomenon. METHODS: In the last 4 years, 525 patients successfully dilated were randomized to receive intravenous heparin (n = 264) or not (n = 261) after the angioplasty. The excluding criteria were contraindications for heparin and risk for abrupt closure (refractory unstable angina, primary coronary angioplasty in acute myocardial infarction, evidence of intracoronary thrombus, intimal tear after the procedure and cases of chronic total occlusions). Both heparin and non heparin groups were similar in respect to female sex (15% x 17%; p = NS), age over 70 years old (7% x 9%; p = NS), previous myocardial infarction (26% x 24%; p = NS), multi-vessel procedures (4% x 7%; p = NS, stable angina (40% x 46%; p = NS), unstable angina (52% x 48%; p = NS) and angioplasty after thrombolytic therapy (8% x 6%; p = NS). RESULTS: The overall incidence of abrupt closure was 2/525 (0.4%), with one case (0.4%) in each group. The in-hospital mortality was 1/525 (0.2%), which occurred in a non-heparin patient, due to a anterior myocardial infarction. Major complications occurred similarly in heparin and non-heparin groups (0.4%). Bleeding complications were observed more frequently in the heparin group (7% x 2%; p = 0.002). All of them were in the catheterization site and none required blood transfusion. Severe systemic bleeding were not observed. CONCLUSION: In patients regarded as low risk for abrupt closure, the incidence of this complication was really low (0.4%) and heparin probably do not prevent it.     

Subendocardial blood flow in children with congenital aortic stenosis

Subendocardial blood flow may be estimated from the ratio of flow to the subendocardium to myocardial oxygen consumption. The first may be estimated from the diastolic pressure time index (area between aortic and left ventricular (LV) pressure during diastole) and the latter by the tension time index (integral of LV pressure during systolic ejection). Subendocardial flow index (SEFI) averaged 1.27 (0.96-1.78) in 13 children with normal aortic valves. SEFI averaged 0.88 (0.43-1.65) in asymptomatic children with congenital aortic stenosis and was never greater than 0.9 in symptomatic children. Aortic valve area and systolic pressure difference did not correlate well with symptoms. SEFI and aortic valve area increased in 26 of 28 patients after surgery. However, 23 of 28 had varying degrees of aortic regurgitation following valvotomy. Since calculation of SEFI is not affected by aortic regurgitation, it would appear to be a more useful measure of surgical success than aortic valve area.     

Palmoplantar keratoderma associated with congenital heart disease

We report the case of a 14-month-old boy suffering from total anomalous pulmonary venous connection (TAPVC) associated with congenital diffuse palmoplantar keratoderma (PPK). An association between TAPVC and PPK has not been described previously, but PPK has been reported in association with a variety of cardiac abnormalities. Given the low frequency of both conditions, a genetic link seems likely. It is therefore advisable for dermatologists to check for heart abnormalities in children with congenital PPK.     

Surfactant decreases pulmonary vascular resistance and increases pulmonary blood flow in the fetal lamb model of congenital diaphragmatic hernia

INTRODUCTION: Experiments using animal models of neonatal respiratory distress syndrome have shown a decrease in pulmonary vascular resistance (PVR) with surfactant replacement, whereas studies with the lamb model of congenital diaphragmatic hernia (CDH) have demonstrated improvement in oxygenation and lung mechanics with this therapy. The aim of the present study was to measure the effects of surfactant replacement therapy on the pulmonary hemodynamics of the lamb model of CDH. METHODS: Ten lambs with surgically created CDH and five control lambs were instrumented at term, with the placental circulation intact. Ultrasonic flow probes were positioned around the main pulmonary artery and the common origin of the left and right pulmonary arteries to record total lung and main pulmonary artery blood flow. Catheters were inserted to record systemic, pulmonary, and left atrial pressure. Five CDH animals received 50 mg/kg of surfactant by tracheal instillation just before delivery. All 15 animals were then ventilated for 4 hours. RESULTS: Correcting the surfactant deficiency in the CDH lamb resulted in a significant increase in pulmonary blood flow, a decrease in PVR, and a reduction in right-to-left shunting. These improvements in hemodynamics were associated with a significant improvement in gas exchange over 4 hours. CONCLUSION: The fetal lamb model of CDH has elevated PVR in comparison to controls. Prophylactic surfactant therapy reduces this resistance and dramatically increases pulmonary blood flow while reducing extrapulmonary shunt. A surfactant deficiency may be partially responsible for the persistent pulmonary hypertension in neonates with CDH.     

Abnormal left ventricular filling after neonatal repair of congenital heart disease: association with increased mortality and morbidity

BACKGROUND: The presence of mid-diastolic flow reversal on the mitral valve Doppler inflow indicates abnormal left ventricular filling. To determine whether mid-diastolic flow reversal predicts outcome in patients undergoing repair or palliation of neonatal congenital heart disease, we reviewed the echocardiograms and medical records of 40 patients with either left ventricular outflow obstruction or transposition of the great arteries. METHODS: All patients underwent surgical repair; transposition of the great arteries (TGA) = 17, coarctation of the aorta (CoA) = 14, interrupted aortic arch (IAA) = 8, and aortic stenosis (AS) = 1. The presence of mid-diastolic flow reversal was determined by pulsed Doppler interrogation of the mitral valve on preoperative and postoperative echocardiograms. RESULTS: Preoperative echocardiograms showed diastolic flow reversal in only 5 patients; 1 of 1 with AS and 4 of 14 with CoA. Twenty-one of 40 patients showed postoperative diastolic flow reversal; 1 of 1 with AS, 8 of 8 with IAA, 1 of 14 with CoA, and 11 of 17 with TGA. Postoperative mid-diastolic flow reversal 1 to 3 days after surgery was associated with higher mortality rate: 7 of 21 patients with diastolic flow reversal and 0 of 19 without diastolic flow reversal died. Patients with diastolic flow reversal who survived had longer intensive care unit (26.2 +/- 13.5 days vs 7.1 +/- 4.1 days, P <.001) and hospital (57.4 +/- 38.8 days vs 14.8 +/- 5.2 days, P <.05) stays. CONCLUSION: Mid-diastolic flow reversal is an indicator of prolonged hospital stay and mortality in patients with left ventricular outflow tract obstruction or TGA.     

Absent mesosternum in congenital heart disease

The association of developmental abnormalities of the sternum with congenital heart disease is well known. These abnormalities include hypoplasia, multiple centers, and premature fusion. The absence of the sternal bodies in patients with congenital heart disease unrelated to a specific syndrome complex has not been previously described. Possible association with congenital pulmonary vascular disease was noted.     

Endovascular stents in congenital heart disease

Acquired or de novo vascular obstructions can adversely affect the outcomes of management algorithms for children with congenital heart lesions. Although surgical repair is frequently feasible, some acquired or congenital obstructions are difficult to address in the operating theater. Presented is the recent experience with endovascular stents to relieve such stenoses, and their impact on patient care.