Coronary Blood Flow Assessed by Transthoracic Echocardiography in Neonates

Coronary flow measurement has provided useful clinical and physiologic information. However, there is little information about values for coronary flow in normal neonates, much less neonates with congenital heart disease. The aim of this study was to assess coronary blood flow in normal neonates and to compare the results with those in infants with ventricular septal defect. The study groups consisted of 12 normal neonates and 9 infants with simple ventricular septal defect associated with pulmonary hypertension. Left ventricular dimension, left ventricular mass, and the diameter of the coronary vessel were measured by standard M-mode and two-dimensional echocardiography. Peak flow velocities, flow velocity integrals, and flow volumes in the left anterior descending and circumflex coronary arteries were measured. The flow signals from the left anterior descending and circumflex coronary arteries were recorded in 84% (10/12) and 17% (2/12), respectively, in the normal neonates and 78% (7/9) and 11% (1/9), respectively, in the patients. The left ventricular end diastolic diameter and mass were significantly lower in normal infants than in the infants with ventricular septal defect (1.56 ± 0.11 vs 1.84 ± 0.09 cm and 5.4 ± 1.6 vs 8.8 ± 0.8 g, respectively, p < 0.01). The mean peak diastolic velocity and the flow velocity time integral in the left anterior descending coronary artery were significantly lower in the normal neonates than in the patients (15 ± 4 vs 28 ± 6 cm/sec and 2.3 ± 0.6 vs 5.9 ± 1.5 cm, respectively, p < 0.01). The coronary flow volume was significantly lower in the normal neonates than in the patients (3.1 ± 1.4 vs 7.9 ± 4.7 ml/min, p < 0.05). However, the flow volume of the left anterior descending coronary artery/left ventricular mass did not show any significant difference between the two groups. Our study demonstrated in neonates that it is feasible to detect noninvasively and to evaluate the flow of the left anterior descending coronary artery under physiologic conditions and abnormal hemodynamic situations. Increased flow volume in the left anterior descending coronary artery in patients with ventricular septal defect may be a compensated mechanism for the increase in oxygen demand of hypertrophic myocardium of the left ventricle.     

Coarctation of the Left Pulmonary Artery: Effects on the Pulmonary Vasculature of Infants

At autopsy, two infants had unsuspected coarctation of the left pulmonary artery (CoLPA), which was produced by an extension of ductal tissue into the wall of the left pulmonary artery. The first case, a 4-month-old girl, also had a ventricular septal defect and an anomalous branching pattern of the innominate arterial trunk. Pulmonary arterial hypertensive changes were noted in the right lung. In contrast, the left lung showed thin-walled pulmonary arteries. The second case, a term female newborn, had exhibited severe unexplained respiratory distress since birth. Histologic sections of the right lung showed dilated pulmonary arteries with thinned media, whereas the left lung showed a persistent fetal arterial pattern. It is believed that the peripheral pulmonary arterial changes are age-dependent and associated with asymmetric blood flow between the right and left pulmonary arteries. CoLPA is a rare pulmonary artery defect, and early diagnosis of this abnormality is important.     

Interparametric Correlation Between Echocardiographic Markers in Preterm Infants With Patent Ductus Arteriosus

Various echocardiographic parameters are determined in the assessment and evaluation of a patent ductus arteriosus. In isolation, many of these parameters have a low sensitivity and specificity for ductal hemodynamic significance compared with ductal size. This study aimed to correlate various echocardiographic parameters with ductal size (transductal diameter) in infants with a symptomatic patent ductus arteriosus and to ascertain the accuracy of various parameters in predicting a duct 3 mm in size or larger. In this retrospective study, preterm infants younger than 32 weeks gestation who were evaluated for the presence of a patent ductus arteriosus during the period June 2010–2012 were assessed. The following echocardiographic parameters were measured: transductal diameter (TDD), ductal velocity, end-diastolic left pulmonary artery flow, ductal diameter-to-left pulmonary artery ratio (TDD:LPA), left atrial-to-aortic root ratio (LA:Ao), left ventricular output-to-superior vena cava flow ratio (LVO:SVC), transmitral E:A ratio, and isovolumic relaxation time (IVRT). The study enrolled 52 infants with a mean gestation age of 26 ± 2 weeks and a mean birth weight of 837 ± 240 g. The mean transductal diameter was 2.8 ± 0.5 mm. Transductal diameter correlated significantly with ductal velocity, end-diastolic LPA flow, TDD:LPA ratio, LA:Ao ratio, and LVO:SVC ratio but not with transmitral indices. The LVO:SVC ratio had the highest specificity (0.83) and sensitivity (0.95) for detecting a duct 3 mm in size or larger, the area under the curve being 0.95 (95 % confidence interval [CI], 0.85–0.99). Significant correlations between ductal size and surrogate markers of pulmonary overcirculation were noted.     

Doppler Echocardiographic Study of the Pulmonary Artery and Its Branches in 114 Normal Neonates

It has been shown that there are pressure gradients between the main pulmonary artery (MPA) and its two branches in infants undergoing catheterization. This study investigated the blood flow velocities and pressure gradients in the right and left pulmonary arteries (RPA and LPA, respectively) in normal neonates. The MPA and its two branches were examined echocardigraphically in 114 term consecutive healthy neonates aged 1–6 days. The pressure gradients between the MPA and RPA or LPA were calculated. Thirty neonates with pressure gradients above 2.5 mmHg were followed by 3–6 months. The peak velocities in the RPA and LPA (1.16 ± 0.19 and 1.01 ± 0.18 m/s) were significantly higher than that in the MPA (0.84 ± 13 m/s) (both p < 0.001), with that in the RPA slightly higher than in the LPA (p < 0.001). There was an estimated pressure gradient of 2.5–8.3 mmHg between the MPA and RPA in 43% and of 2.5–6.6 mmHg between the MPA and LPA in 16.7% of all neonates. The gradients disappeared within 3–6 months in 12 (40%) of the 30 neonates with an initial gradient above 2.5 mmHg. The differences in blood flow velocities or pressure gradients in the RPA or LPA were probably attributable to the variations in pulmonary arterial pressure, cardiac output, age, and birth weight and can be considered physiologically characteristic in neonates.     

Acute loads applied to the right ventricle: Effect on left ventricular filling dynamics in the presence of an open pericardium

To determine whether diastolic ventricular interdependence mechanisms would act in the presence of an open pericardial sac, as during cardiac surgery, moderate acute right ventricle afterload increases were applied to eight dogs with the chest and pericardium open while left ventricular filling dynamics were being assessed by Doppler echocardiography. Dogs were studied under basal conditions and after acute banding of the main pulmonary artery tightened to produce a 100% increase in right ventricular systolic pressure. With banding, the left ventricular filling velocity ratio (E/A), as assessed by Doppler echocardiography of mitral inflow, changed from a baseline value of 1.32 ± 0.05 to 1.16 ± 0.03 (p < 0.02), suggesting a restrictive pattern to early left ventricular filling, which is differed to that during the second half of diastole. Isovolumic relaxation time, measured as the time interval between aortic valve closure and mitral valve opening, assessed by M-mode echocardiography of both valves, was prolonged, though not significantly, from 63.3 ± 2.5 ms to 69.4 ± 2.9 ms, by banding of the pulmonary artery. E wave deceleration time, a filling variable influenced by chamber pressure/volume relations, was shortened by pulmonary artery banding, changing from 75.1 ± 1.7 ms to 68.0 ± 1.8 ms (p < 0.01). It was concluded that pressure loads applied to the right ventricle restricted early left ventricular filling. Prolonged relaxation and altered pressure–volume chamber relations were the diastolic interdependence mechanisms involved that proved to be acting even under open pericardium conditions.     

Surgical Cutdown of the Right Carotid Artery for Aortic Balloon Valvuloplasty in Infancy: Midterm Follow-Up

A vascular approach for balloon aortic dilatation in infants is of major concern due to the high risk of femoral artery injury. To overcome this problem, a surgical right carotid artery (RCA) approach has been advocated. No reports are available on RCA after neonatal cutdown. Since 1990, RCA cutdown has been performed in 29 infants with congenital aortic stenosis. Periprocedural complications included one asymptomatic occlusion and one transient trauma of the stellate ganglion. At a mean follow-up of 4.4 ± 2.2 years from aortic valvuloplasty, ultrasound assessment of morphology and flow of RCA was performed in 17 children. RCA was patent in all patients. The mean ratio of right/left carotid artery diameter was 0.95 ± 0.16 (range 0.65–1.2). The site of surgical incision could be identified in 5 children in the absence of flow disturbance. A 6-year-old asymptomatic girl, who underwent two procedures, had a 35% reduction of RCA diameter at the site of cannulation and turbulent flow at Doppler interrogation, indicating mild obstruction. Our data demonstrate that RCA is well preserved after neonatal surgical cutdown; asymptomatic obstruction can occasionally be present.     

Branch Pulmonary Artery Growth After Blalock–Taussig Shunts in Tetralogy of Fallot and Pulmonary Atresia with Ventricular Septal Defect: A Retrospective, Echocardiographic Study

We performed a retrospective echocardiographic study in tetralogy of Fallot (TOF) or pulmonay atresia with ventricular septal defect (PA&VSD) to evaluate the effects of Blalock–Taussig shunt on branch pulmonary artery growth. There were 35 patients with TOF and 11 with PA&VSD. We measured the right and left pulmonary artery area index and also the combined pulmonary artery area index, both before and after shunt operation. The mean ± SD of these three variables before the shunt operation in the TOF group were 63.5 ± 22.5, 57.8 ± 24.9, and 121.4 ± 42.8 mm²/m²; after shunt operation they were 98.5 ± 33.6, 85.9 ± 31.9, and 184.0 ± 59.8 mm²/m², respectively (p values <0.0001, <0.0002, and <0.0001, respectively). In the PA&VSD group the comparable values before shunt operation were 66.5 ± 16.0, 55.4 ± 10.6, and 120.9 ± 26.9 mm²/m² and after shunt operation were 90.5 ± 22.9, 77.2 ± 24.1, and 166.6 ± 44.4 mm²/m², respectively (p values <0.0006, <0.014, and <0.002, respectively). We also examined the effect of distensibility of pulmonary arteries by comparing the percentage change in size of the combined pulmonary artery area index in the first 4 months after shunt with those after this time (p < 0.023). There were no significant differences between left- and right-sided shunts, origin and distal pulmonary artery growth, and the TOF and PA&VSD groups.     

Noninvasive evaluation of systolic pressures of pulmonary artery and right ventricle using contrast-enhanced doppler echocardiography: Comparative study using sonicated albumin or glucose solution

Evaluation of pulmonary arterial pressure is essential for the diagnosis and management of patients with congenital heart disease; it is usually done by cardiac catheterization. An alternative, noninvasive method may be clinically more useful. The purpose of this study was to assess the usefulness of the noninvasive determination of systolic pressure of the pulmonary artery and right ventricle by contrast-enhanced Doppler echocardiography. We selected 30 pediatric patients (28 with trivial or nonsignificant tricuspid regurgitant Doppler signals and 2 with significant tricuspid regurgitant Doppler signals) aged 2 months to 21 years. The flow velocity of tricuspid regurgitation was measured with continuous-wave Doppler of the right ventricular inflow view or left parasternal or apical four-chamber view before and after injection of two types of contrast medium (hand-agitated 5% glucose or sonicated albumin). The systolic pressure of the pulmonary artery was assessed as the estimated right ventricular systolic pressure (albumin method) minus the peak pressure gradient across the pulmonary valve (nonenhanced Doppler method). After injection of hand-agitated 5% glucose and sonicated albumin, trivial tricuspid regurgitation signals were enhanced in 25 of 28 patients (89%). In two patients, spectral envelopes were well defined enough to obtain the peak systolic velocity of the tricuspid regurgitation jet without contrast medium injection. Peak velocity was not altered by injection of contrast medium in these patients. There was significant correlation between the estimation by contrast-enhanced Doppler using hand-agitated 5% glucose and the cardiac catheterization measurement of the transtricuspid pressure gradient (r= 0.88). The transtricuspid pressure gradients obtained by continuous-wave Doppler during sonicated albumin enhancement corresponded closely to those measured by cardiac catheterization (r = 0.95). Pulmonary arterial and right ventricular systolic pressures measured by Doppler using sonicated albumin and those obtained by cardiac catheterization were highly correlated (right ventricle, r = 0.96; pulmonary artery, r = 0.95). In conclusion, this technique may be a valuable noninvasive method for determining accurate right ventricular and pulmonary arterial systolic pressures.     

The Histology of the Lung in Neonates with Tricuspid Valve Disease and Gross Cardiomegaly Due to Severe Regurgitation

Lung autopsies from four neonates with Ebstein's anomaly or tricuspid valve dysplasia and gross cardiomegaly were examined. The mean cardiothoracic ratio was 92 ± 0.5%. The degrees of pulmonary hypoplasia and pulmonary artery muscularization were assessed and were compared with those in lungs from four controls and four patients with diaphragmatic hernias. Lung and body weight ratios and radial alveolar counts, which reflect pulmonary hypoplasia and immaturity, were significantly decreased only in patients with diaphragmatic hernia. The thickness of the medial muscle layer in small pulmonary arteries was greater in patients with diaphragmatic hernia; however, in patients with tricuspid valve disease, it was relatively small. Abnormal vascular muscle extension was seen only in patients with diaphragmatic hernia. In the cases of tricuspid valve disease, although cardiomegaly and lung compression were severe, lung hypoplasia and immaturity were not, and neither abnormal medial thickening nor extension were found. Our results suggest that, at least in full-term infants with tricuspid valve disease, surgical relief of lung compression may improve respiratory function, even if the cardiomegaly is severe.     

Increase in Pulmonary Arterial Diameter Under Prostaglandin E1 Therapy in Infants with Cyanotic Congenital Heart Disease

We studied the change in pulmonary arterial diameter under prostaglandin E₁ (PGE₁) therapy in infants with ductus-dependent cyanotic heart disease (pulmonary atresia). Ten infants undergoing administration of PGE₁ for more than 2 weeks were selected for this study. A classic Blalock–Taussig (BT) shunt was performed in seven patients and a modified BT shunt in three. The shunt was successful in all patients. The internal diameters of the right and left pulmonary arteries were measured before and after the start of PGE₁ therapy using two-dimensional echocardiography. The pulmonary arterial index (PA index) was calculated to correct the diameters for body surface area. Both pulmonary arteries enlarged during the first week of PGE₁ therapy in all 10 patients. Further increases in the two diameters were observed even after the first week of treatment in nine patients. Both the mean diameters at 2 weeks after the start of PGE₁ were about 50% larger than the initial diameters (right; increased from 3.1 to 4.7 mm; left; increased from 3.0 to 4.4 mm). Of the eight patients given PGE₁ for more than 3 weeks, four showed no changes in pulmonary arterial diameters after the first 2 weeks and the remaining four showed a slight increase. PA indexes also showed a rapid increase during the first 2 weeks and no significant change thereafter. We suggest that, in infants with pulmonary atresia and small pulmonary arteries, the optimal pulmonary artery size for BT shunt insertion is achieved after 2 weeks of PGE₁ infusion, with no further significant increase in size being observed after this time.     

Haemodynamic effects of altering arterial oxygen saturation in preterm infants with respiratory failure.

AIMS: To examine the haemodynamic effects of brief alteration in arterial oxygenation in preterm infants with respiratory failure. METHODS: Eighteen preterm infants with respiratory failure, aged 9-76 hours, underwent detailed Doppler echocardiographic assessment at 86%, 96%, and 100% SaO2, achieved by altering the FIO2. Sixteen were receiving intermittent positive pressure ventilation, median FIO2 0.45 (0.20-0.65), median mean airway pressure 12 cm H2O (0-20). SaO2 was stable for 15 minutes at each stage. Four parameters of pulmonary arterial pressure were measured: peak velocity of tricuspid regurgitation and peak velocity of left to right ductal flow, TPV:RVET ratio and PEP:RVET ratio, measured at the pulmonary valve, along with flow velocity integrals at the aortic and pulmonary valves, and systemic arterial pressure. Ductal size was graded into closed, small, moderate, large with imaging, pulsed and continuous wave Doppler. RESULTS: Between 86% and 96% SaO2, there were no consistent changes, but in three of the 12 with a patent ductus arteriosus (PDA) there was ductal constriction, with complete closure in one. Between 96% and 100% SaO2, peak ductal flow velocity rose significantly in four of eight with a PDA. Ductal constriction occurred in four infants; in three this was associated with a significant fall in aortic flow integral and a rise in aortic pressure (4-6 mm Hg). Overall, 11 infants went from 86% to 100% SaO2 and pulmonary arterial pressure fell significantly in seven. CONCLUSION: A brief rise in SaO2 within the range maintained by most neonatal units can cause significant ductal constriction. The fall in pulmonary arterial pressure with 100% SaO2 seen in most infants was associated with a fall in pulmonary blood flow (or no change), rather than a rise, indicating that the dominant haemodynamic effect was ductal constriction rather than pulmonary vasodilation.     

Abnormal blood flow patterns in renal arteries of small preterm infants with patent ductus arteriosus detected by Doppler ultrasonography

Blood flow velocities and pulsatory indices in both renal arteries (RAs) and in the internal carotid artery (CAI) were measured by pulsed Doppler ultrasonography in ten preterm infants with patent ductus arteriosus (PDA), before and after surgical ligation. The results obtained in the RAs were compared to those found in a reference group of 22 stable preterm infants. In the RAs the diastolic steal volume of the PDA led to a marked decrease in diastolic blood flow velocity (range 3 to-23 cm/s). Seven infants showed retrograde diastolic flow, whereas only three infants had these flow patterns in the CAI. In the RAs, the peak systolic blood flow velocities (range 56 to 135 cm/s) exceeded the values found in the reference group by 85% on average. The pulsatility indices reached values of above 1,00. In spite of the increase in systolic flow velocities before surgery, the time mean of maximum velocities was significantly lower than those measured after surgery and in the reference group. After PDA ligation, blood flow velocities normalized. The present study shows that a large PDA may induce abnormal flow patterns even in the RAs. These flow patterns may predispose to renal hypoperfusion and subsequent impairment of renal function.Abbreviations CAI internal carotid artery - NFC necrotizing enterocolitis - PDA patent ductus arteriosus - PI pulsatility index - RA renal artery - Vd end-diastolic velocity - V_max time mean of maximum velocity - Vs peak systolic velocity     

Origin of the Main Pulmonary Artery from the Left Coronary Artery in Complex Pulmonary Atresia

We describe a 22-year-old woman with a history of unrepaired pulmonary atresia with ventricular septal defect. This woman was interesting in that her main pulmonary artery and right pulmonary artery arose from the left main coronary artery. She developed significant pulmonary hypertension in addition to isolation of the left pulmonary artery following ductal closure, subsequent to which the majority of her pulmonary blood flow was coronary dependent.     

Postnatal Changes in Left Ventricular Volume and Contractility in Healthy Term Infants

To evaluate how the size of the ductus arteriosus affects neonatal left ventricular (LV) volume and contractility, we serially obtained two-dimensional and Doppler echocardiograms at 2, 12, 24, and 120 hours after birth in 20 healthy infants. LV volume was calculated by the biplanar Simpson's rule, and ductus arteriosus size with left-to-right shunting was measured by two-dimensional and Doppler echocardiography. At 2 hours, the ductus arteriosus was at its maximal size, and the LV end-diastolic volume was 1.2-fold higher than at the subsequent hours after birth. Additionally, there was a significant linear correlation between the end-diastolic volume and the ductal diameter. In contrast, the peripheral vascular resistance, derived from blood pressure measurements and Doppler echocardiography, was lowest at 2 hours of age. The mean normalized systolic ejection rate, an index of contractility, remained constant throughout the study period. These results suggest that alterations in the LV end-diastolic volume soon after birth depend on changes in ductal flow, which in turn is affected by ductal diameter, and that the neonatal left ventricle operates at its maximal performance with limited contractility during ductal patency.     

Congenital Pulmonary Steal Phenomenon Associated with Tetralogy of Fallot, Right Aortic Arch, and Isolation of the Left Subclavian Artery

Isolation of the left subclavian artery has been reported in cases of tetralogy of Fallot with a right aortic arch. As the isolated left subclavian artery is supplied by the left vertebral artery (in which the blood flow direction is inverted), this anomaly is usually responsible for a congenital subclavian steal phenomenon. In our case the isolated left subclavian artery was connected by a patent ductus arteriosus to the main pulmonary artery. Therefore the left vertebral artery did not supply the distal left subclavian artery but supplied the main pulmonary artery (congenital pulmonary artery steal).     

Effects of Transdermal Nitroglycerin in Children with Congestive Heart Failure: A Doppler Echocardiographic Study

The aim of this study was to evaluate by Doppler echocardiography whether administration of transdermal nitroglycerin (NTG) to children with congestive heart failure could modify mitral flow velocity profile with redistribution of left ventricular filling to late diastole, suggesting preload reduction of the left ventricle. Twelve children with congestive heart failure, aged from 6 months to 6 years (2.83 ± 2.24 years; mean ± SD), were recruited. Patients were randomly allocated either a NTG patch (study group; n= 6) or a placebo patch (control group; n= 6) in a double-blind procedure. The NTG patch was a 10-cm² patch releasing 5 mg of NTG per day. NTG patches were adjusted to a dose of 1 cm²/kg/day (0.5 mg/kg/day). Peak velocity and time–velocity integral (TVI) of E and A waves of transmitral flow, the ratio of the velocities of the A wave and E wave, and the ratio of the TVI of the A wave to the TVI of the E wave were measured. Doppler measurements were determined before treatment (H0) and 4 hours (H4) and 23 hours (H23) after the patch application. Relative changes of these parameters were not significantly different between these two groups. In the NTG group, mean NTG plasma concentration was 1.08 ± 0.47 μg Liter⁻¹ at H4 (n= 5) and 1.18 ± 0.81 μg Liter⁻¹ at H23 (n= 5). No patient had a NTG plasma concentration greater than 2 μg Liter⁻¹ either at H3 or at H24. These data suggest that 1 cm²/kg transdermal doses of NTG may have a limited bioavailability or a higher clearance and minimal hemodynamic effects in children with congestive heart failure already receiving other medications, implying that higher doses should be used.     

Generation of Reactive O2 Species in the Myocardium of Newborn Lambs Following Intrauterine Increase in Right Ventricular Pressure

Fetuses with pulmonary stenosis and constriction of the ductus arteriosus or the recipient twin in the context of a twin-to-twin transfusion syndrome may present with severe right ventricular myocardial dysfunction. Free O₂ radicals are known to be increased in hypertrophied adult myocardium secondary to an increase in endocavitary pressure. This study investigates whether products of reactive O₂ species generation are abnormally elevated in the myocardium of fetuses with increased right ventricular pressure. Banding of the main pulmonary artery was performed in five fetal lambs at 90 to 100 days of gestation. Three other animals had a sham intervention and were used as controls. Postoperative observation lasted on average 42 days (range 33–49 days). The levels of hydroperoxides were found to be significantly higher in the right ventricle of the stenosed lambs (6.6 ± 3.5 nmol/mg protein) compared to the left ventricle of the same lambs (0.7 ± 0.7 nmol/mg protein), and compared to the right (0.12 ± 0.1 nmol/mg protein) and the left (0.5 ± 0.8 nmol/mg protein) ventricles of the controls. It is concluded that during fetal life, an increase in right ventricular pressure is associated with a marked accumulation of products of reactive O₂ species generation in the right ventricular myocardium.     

Subclavian Steal Syndrome in Anomalous Connection of the Left Subclavian Artery to the Pulmonary Artery in D-Transposition of the Great Arteries

Several reports have documented the occurrence of an isolated left subclavian artery in association with both tetralogy of Fallot and double-outlet right ventricle. In certain cases a congenital subclavian or pulmonary artery steal syndrome exists in which the left subclavian artery is connected to the main pulmonary artery via a ductus arteriosus. We describe a subclavian steal syndrome secondary to anomalous origin of the left subclavian artery from the pulmonary artery in d-transposition of the great arteries in a patient with Spondylocostal dysostosis (SCD). Cardiac anomalies are rare in SCD and this constellation of findings have not previously been described.     

Internal carotid artery blood flow velocities before, during, and after extracorporeal membrane oxygenation.

Blood flow velocities in the internal carotid arteries were studied with pulsed Doppler in 25 neonatal patients (birth weight range, 2600 to 4100 g) who had extracorporeal membrane oxygenation (ECMO). Time averaged mean systolic, mean diastolic, and mean blood flow velocities were calculated. Five infants had right common carotid artery reconstruction. Blood flow velocities measured in 15 healthy full-term infants were used as controls. Findings during ECMO included the following: (1) forward flow in the right internal carotid artery in 50% of the infants; (2) significant increase in the mean diastolic and the mean flow velocities (48% and 128%, respectively) in the left internal carotid artery when compared with pre-ECMO and control infants' values; (3) the elevation in the mean and the mean diastolic velocities was associated with changes in the PaCO2 and with an increase in the diastolic blood pressure; and (4) forward blood velocities in the right internal carotid artery were comparable with blood velocities in the left internal carotid artery and with the blood velocities of control infants. After ECMO, the mean diastolic velocity in the left internal carotid artery decreased significantly, but it remained elevated when compared with pre-ECMO values. Infants with right common carotid reconstruction had blood velocities in the right internal carotid artery comparable with the simultaneous blood velocities in the left internal carotid artery and to the blood velocities of control infants. Twenty-eight percent of the infants had major neuroanatomic lesions. Right or left preponderance was not noted. No association between blood velocity values in the internal carotid arteries or flow direction and the presence or the absence of brain lesions was noted.     

Persistent Left Fifth Aortic Arch Associated with Tetralogy of Fallot

A case of persistent left fifth aortic arch, forming a congenital ``double-lumen' aortic arch, has been diagnosed on angiocardiography during life. It appeared as an unusual vascular structure running inferiorly and parallel to the ``real' aortic arch from the innominate artery to the left subclavian artery superior to the pulmonary artery. This anomaly was found in the setting of tetralogy of Fallot, an association never described before, with patent ductus arteriosus (previously reported in most cases). The left aortic arch in this case was not a source of pulmonary circulation, as described in previous cases with pulmonary atresia and ventricular septal defect, but was a systemic-to-systemic connection without functional relevance.