The morphological spectrum of ventricular noncompaction.
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Animals↗
Biomedical subjects
Shi-Joon Yoo
Publications and source records attributed to Shi-Joon Yoo.
Answer to case of the month #102. Ortner's syndrome (cardiovocal syndrome).
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Adolescent↗
Comparative imaging of differential pulmonary blood flow in patients with congenital heart disease: magnetic resonance imaging versus lung perfusion scintigraphy.
BACKGROUND: Lung perfusion scintigraphy is considered the gold standard to assess differential pulmonary blood flow while magnetic resonance (MR) has been shown to be an accurate alternative in some studies. OBJECTIVE: The purpose of the study was to assess the accuracy of phase contrast magnetic resonance (PC-MR) in measuring pulmonary blood flow ratio compared with lung perfusion scintigraphy in patients with complex pulmonary artery anatomy or pulmonary hypertension and to document reasons for discrepant results. MATERIALS AND METHODS: We identified 25 cases of congenital heart disease between January 2000 and 2003, in whom both techniques of assessing pulmonary blood flow were performed within a 6-month period without an interim surgical or transcatheter intervention. The study group included cases with branch pulmonary artery stenosis, intracardiac shunts, single ventricle circulation, pulmonary venous anomalies and conotruncal defects. The mean age at study was 5.7 years (range 0.33-12) with a mean weight of 20.3 kg (range 6.5-53.6). The two methods were compared using a Bland-Altman analysis, and the Pearson correlation coefficient was calculated using the lung scan as the gold standard. Discrepant results were examined by reviewing the source images to elucidate reasons for error by MR. RESULTS: Bland-Altman analysis comparing right pulmonary artery (RPA) blood flow percentage, as measured by each modality, showed a mean difference of 1.43+/-9.8 (95% limits of agreement: -17.8, 20.6) with a correlation coefficient of r=0.84, P<0.0001. In six (24%) cases a large difference (>10%) was found with a mean difference between techniques of 17.9%. The reasons for discrepant results included MR artifacts, dephasing owing to turbulent flow, site of data acquisition and lobar lung collapse. CONCLUSION: When using PC-MR to assess pulmonary blood flow ratio, important technical errors occur in a significant proportion of patients who have abnormal pulmonary artery anatomy or pulmonary hypertension. If these technical errors are avoided, PC-MR is able to supply both anatomic and quantitative functional information in this patient population.
Child↗
In vivo MRI measurement of blood oxygen saturation in children with congenital heart disease.
OBJECTIVE: The purpose of this prospective study was to measure in vivo blood oxygen saturation (%O2) by MRI in children with congenital heart disease (CHD) using population-based values for T2O (T2 signal decay of fully oxygenated blood) and K (a parameter representing the deoxyhemoglobin effect) and compare the %O2 with direct cardiac catheterization measurements. BACKGROUND: MRI can determine %O2 using in vivo measurement of signal decay (T2) and an in vitro calibration curve relating T2 and %O2, based on the equation: 1/T2 = 1/T2O + K(1-%O2/100)2. Recent studies have correlated the T2/%O2 in children with CHD with the adult calibration statistics. METHODS: A total of ten children (five male, five female) with single ventricle CHD (median age 4.8 months, range 2 months to 4.4 years) undergoing cardiac catheterization were included in the study. The blood T2 measurements for each patient were performed in a 1.5 T GE CV scanner. The %O2 was then calculated based on the equation using values of T2O determined from individual hematocrits, and a population average value of K derived for children. The %O2 values were compared with direct %O2 measurements from cardiac catheterization. RESULTS: The %O2 values by MRI were strongly correlated with direct cardiac catheterization measurements (R = 0.825; P < 0.001). CONCLUSION: The study indicates that the noninvasive measurement of %O2 by MRI can accurately measure oxygen saturation in children with complex CHD.
Aorta↗
The biological "scrabble" of pulmonary arteriovenous malformations: considerations in the setting of cavopulmonary surgery.
Pulmonary arteriovenous fistulas are vascular malformations, which, by virtue of producing abnormal vascular connections proximal to the units of gas exchange, result in intrapulmonary right-to-left shunting. These malformations or fistulas reflect at least in part disordered angiogenesis, and less commonly recruitment and dilation of pre-existing vascular channels. Pulmonary arteriovenous fistulas occur in a number of diverse clinical settings. Such fistulas are a well-established feature of the Weber-Osler-Rendu complex, or hereditary haemorrhagic telangiectasia, an autosomal dominant vascular dysplasia characterized by mucocutaneous telangiectasis, epistaxis, gastrointestinal haemorrhage, and arteriovenous malformations in the lung, brain, liver and elsewhere. They are also seen in the patient with acute or chronic liver disease, disease that is usually but not invariably severe, or those with non-cirrhotic portal hypertension. They may occur as congenital malformations, single or diffuse, large or small in isolation, and when large or extensive enough may result in hypoxaemia, clinical cyanosis, and heart failure. Cerebral vascular accidents are also a well-known complication of this disorder. An extensive literature has accumulated with regard to the pulmonary arteriovenous fistulas seen in the setting of the Weber-Osler-Rendu complex, and there is considerable information on the genetics, basic biology, clinical findings, complications and therapeutic interventions of these malformations in the setting of this syndrome. These issues, however, are not the primary considerations of this review, although some aspects of this fascinating disorder will be discussed later. Rather the focus will be on pulmonary arteriovenous malformations that develop in the setting of cavopulmonary surgery, and their relationship to the pulmonary arteriovenous fistulas occurring in the hepatopulmonary syndrome. The complex tapestry of these overlapping and intersecting clinical observations will be unfolded in the light of their chronology.
Angiography↗
Designing therapeutic strategies for patients with a dominant left ventricle, discordant ventriculo-arterial connections, and unobstructed flow of blood to the lungs.
The palliation of the cyanotic child with a dominant morphologically left ventricle, discordant ventriculo-arterial connections, and obstruction to the pulmonary outflow tract has continued to evolve and mature. The evolution began in the early days of surgical palliation with the Blalock-Taussig shunt, extended to construction of cavopulmonary shunts, if required, and then to the Fontan procedure and its subsequent modifications. This journey took nearly 30 years to complete. There is increasing clinical data to document the beneficial effects of this approach, with ever-improving outcomes. Some aspects of the history of the cavopulmonary shunt have been previously reviewed in this journal and elsewhere, as have analysis of outcomes for some groups of patients considered for surgical completion of the Fontan circulation. While there has been some ongoing interest in ventricular septation since the early success of Sakakibara et al., this approach has largely been abandoned. Considerably more challenges and debate resonate in the surgical algorithms defined for patients whose hearts are characterized by a dominant left ventricle, discordant ventriculo-arterial connections, and unobstructed flow of blood to the lungs. This latter group will be the focus of this review, as will the aetiology of the myocardial hypertrophy that is particularly frequent in this group of patients, its clinical recognition, indeed its anticipation, and the multiple surgical strategies designed to prevent or treat it. All these manoeuvres are considered to optimise suitability for, and outcome from, creation of the Fontan circulation.
Cardiac Surgical Procedures↗
Hemoptysis: a rare cause can be related to a bronchial varix due to pulmonary venous obstruction.
Bronchial varices, which have rarely been described in the radiology literature, can be the result of pulmonary venous obstruction and may present with hemoptysis. This case is an illustration of this rare condition, which correlates CT findings with bronchoscopic findings. We also describe the findings on phase-contrast MR that demonstrated reversed diastolic flow in the branch pulmonary artery supplying the affected lung.
Bronchi↗
Congenital extrahepatic portosystemic shunts.
BACKGROUND: A congenital extrahepatic portosystemic shunt (CEPS) is uncommon. A type 1 CEPS exists where there is absence of intrahepatic portal venous supply and a type 2 CEPS where this supply is preserved. The diagnosis of congenital portosystemic shunt is important because it may cause hepatic encephalopathy. OBJECTIVE: To describe the clinical and imaging features of three children with CEPS and to review the cases in the published literature. MATERIALS AND METHODS: The diagnostic imaging and medical records for three children with CEPS were retrieved and evaluated. An extensive literature search was performed. RESULTS: Including our cases, there are 61 reported cases of CEPS, 39 type 1 and 22 type 2. Type 1 occurs predominantly in females, while type 2 shows no significant sexual preponderance. The age at diagnosis ranges from 31 weeks of intrauterine life to 76 years. Both types of CEPS have a number of associations, the most common being nodular lesions of the liver ( n=25), cardiac anomalies ( n=19), portosystemic encephalopathy ( n=10), polysplenia ( n=9), biliary atresia ( n=7), skeletal anomalies ( n=5), and renal tract anomalies ( n=4). CONCLUSION: MRI is recommended as an important means of diagnosing and classifying cases of CEPS and examining the associated cardiovascular and hepatic abnormalities. Screening for CEPS in patients born with polysplenia is suggested.
Child, Preschool↗
Phase-contrast MR assessment of pulmonary venous blood flow in children with surgically repaired pulmonary veins.
BACKGROUND: Pulmonary venous (PV) obstruction may complicate surgical repair of PV abnormalities. By combining phase-contrast cine (PC) imaging and contrast-enhanced angiography, magnetic resonance (MR) imaging can provide physiological information complementing anatomical diagnosis. OBJECTIVES. To compare the PV flow pattern observed after surgical repair of PV abnormalities with normal PV flow pattern and to investigate the changes occurring in the presence of PV stenosis by using PC MR in children. MATERIALS AND METHODS: By using PC MR, PV flow was evaluated in 14 patients (3 months-14 years) who underwent surgical repair for PV abnormalities. Eleven children (8-18 years) were studied as normal controls. Peak flow velocities and patterns were compared among three groups: normal veins ( n=23), surgically repaired veins without ( n=44) and with stenosis ( n=10). RESULTS: Normal and unobstructed pulmonary veins after surgery showed a biphasic or triphasic flow pattern with one or two systolic peaks and a diastolic peak. Unobstructed surgically repaired veins showed decreased peak systolic velocity ( P =0.001) and an increased peak diastolic velocity ( P=0.005) when compared to normal values. Obstructed veins showed decreased systolic and diastolic velocities when measured upstream from the stenosis. CONCLUSION: PC MR shows different flow patterns among normal, surgically repaired pulmonary veins with and without stenosis.
Adolescent↗
Differential regurgitation in branch pulmonary arteries after repair of tetralogy of Fallot: a phase-contrast cine magnetic resonance study.
BACKGROUND: The importance of pulmonary regurgitation (PR) after repair of tetralogy of Fallot (TOF) is increasingly recognized, but little is known regarding its underlying mechanisms. This phase-contrast cine magnetic resonance (PC MR) study was performed to evaluate the relative contribution of each lung to total regurgitant volume. METHODS AND RESULTS: Twenty-two patients with significant PR underwent a PC MR 3 to 16 years after repair of TOF. Regurgitant fraction of the main pulmonary artery was 39+/-10%. Regurgitant fraction of the left pulmonary artery (LPA; 46+/-18%) was greater than that of the right pulmonary artery (34+/-16%; P=0.002). The average contribution of the LPA to the total regurgitant flow volume was 54+/-19%, whereas its average contribution to the total forward flow volume was 44+/-13% (P=0.002). In 4 patients, regurgitant flow in the LPA accounted for 75% to 100% of the total regurgitant flow. There was a linear relationship between regurgitant fraction and fraction of the regurgitant flow duration in the main pulmonary artery (P<0.001) and right pulmonary artery (P=0.001) but not in the LPA (P=0.129). CONCLUSIONS: PR after repair of TOF is commonly associated with differential regurgitation in the branch pulmonary arteries, which is usually greater in the LPA. Although the cause of this disparity requires further investigation, those patients with a significant unilateral contribution to total PR may be amenable to localized techniques to reduce regurgitation.
Adolescent↗
Neuroblastoma with atypical metastases to cardiac and skeletal muscles: MRI features.
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Heart Defects, Congenital↗
Staged rehabilitation of ductal origin of the left pulmonary artery in an infant Fallot's tetralogy.
Isolation of a branch pulmonary artery from ductal closure is an unusual finding in patients with tetralogy of Fallot. A case report of a newborn is presented where the closing arterial duct was balloon-dilated and stented to reestablish blood supply to the affected lung as a strategy of improving systemic saturations and promoting the growth of the hiliar branch pulmonary artery. Five months after the initial palliation, complete surgical repair with stent removal was successfully achieved.
Abnormalities, Multiple↗
Assessment of the thymus at echocardiography in fetuses at risk for 22q11.2 deletion.
OBJECTIVES: An absent or hypoplastic thymus is common in patients with 22q11.2 deletion (del22q11.2). We sought to determine whether fetal echocardiography could identify absence of the thymus as a diagnostic tool in pregnancies at risk for fetal del22q11.2. METHODS: We evaluated the fetal thymus in 16 consecutive pregnancies at risk for fetal del22q11. Fourteen of the fetuses had a conotruncal cardiac lesion, one had a twin with a conotruncal lesion, and in one the mother had a diagnosis of del22q11.2. The fetal thymus assessment was performed by an individual who was not aware of the del22q11.2 status of the fetus. RESULTS: By 2D imaging, the thymus was identified in the anterosuperior mediastinum as a subtle hypoechogenic area. In nine cases, the thymus was demonstrated prenatally and none had del22q11.2. However, in one case the thymus was only seen on follow-up fetal echocardiography. In six cases, the thymus could not be identified and all six had del22q11.2. In one additional case, analyzed retrospectively, the thymus could not be assessed. The status of the thymus was confirmed on postnatal echocardiography or autopsy in 11 of the 15 cases assessed prenatally. CONCLUSIONS: Our study suggests that fetal echocardiography can assess the thymus in most cases at risk for del22q11.2. This information may be useful in counseling women/couples who decline amniocentesis or who are awaiting amniocentesis results.
Adult↗
Effect of increasing depth of propofol anesthesia on upper airway configuration in children.
BACKGROUND: The upper airway tends to be obstructed during anesthesia in spontaneously breathing patients. The purpose of the current study was to determine the effect of increasing depth of propofol anesthesia on airway size and configuration in children. METHODS: Magnetic resonance images of the upper airway were obtained in 15 children, aged 2-6 yr. Cross-sectional area, anteroposterior dimension, and transverse dimension were measured at the level of the soft palate, dorsum of the tongue, and tip of the epiglottis. Images were obtained during infusion of propofol at a rate of 50-80 microg.kg-1.min-1 and after increasing the depth of anesthesia by administering a bolus dose of propofol and increasing the infusion rate to 240 microg.kg-1.min-1. RESULTS: Overall, the cross-sectional area of the entire pharyngeal airway decreased with increasing depth of anesthesia. The reduction in cross-sectional area was greatest at the level of the epiglottis (24.5 mm2, 95% confidence interval = 16.9-32.2 mm2; P < 0.0001), intermediate at the level of the tongue (19.3 mm2, 95% confidence interval = 9.2-29.3 mm2; P < 0.0001), and least at the level of the soft palate (12.6 mm2, 95% confidence interval = 2.7-22.6 mm2; P < 0.005) in expiration and resulted predominantly from a reduction in anteroposterior dimension. The airway cross-sectional area decreased further in inspiration at the level of the epiglottis. The narrowest portion of the airway resided at the level of the soft palate or epiglottis in the majority of children. CONCLUSION: Increasing depth of propofol anesthesia in children is associated with upper airway narrowing that occurs throughout the entire upper airway and is most pronounced in the hypopharynx at the level of the epiglottis.
Anesthesia, Intravenous↗
Characterization and treatment of systemic venous to pulmonary venous collaterals seen after the Fontan operation.
OBJECTIVES: To determine the anatomical characteristics of systemic venous collaterals formed after the Fontan operation, and the efficacy of a transcatheter strategy for management. METHODS: We reviewed retrospectively the data from cardiac catherization of 50 persistently cyanotic patients after the Fontan operation. RESULTS: A total of 54 transcatheter interventions were performed, at a mean age of 6.3 +/- 3.5 years, a mean interval of 2.7 +/- 2.9 years from completion of the Fontan circulation. Of 38 patients who had fenestration of the baffle at the time of surgery, 25 had patency of the fenestration, and 24 had the fenestration occluded with a device at the time of interventional treatment for associated venous collaterals. We identified a total of 68 systemic venous collateral channels, of which 36 (53%) were supracardiac, 12 (18%) cardiac, and 20 (29%) infracardiac in origin. The most common site of origin was the brachiocephalic vein (44%), followed by the left phrenic vein (25%). A longer time from surgery, at 3.3 +/- 3.4 years, was associated with the identification of collaterals having a diameter larger than 4 mm (p < 0.01). The mean pulmonary arterial pressure was higher in those with larger compared to those with smaller collaterals (13.3 +/- 2.8 versus 11.1 +/- 2.0 mmHg, p < 0.01). Coils were used for occlusion of 61 vessels, and a Rashkind occluder for the remaining 7. After exclusion of the patients undergoing simultaneous closure of their fenestration, systemic saturation of oxygen increased from 89 +/- 6% to 95 +/- 3% (p < 0.01). CONCLUSION: Venous collateral channels are common in patients suffering progressive cyanosis in the setting of the Fontan circulation. The collaterals increase in size with time, and are associated with higher pulmonary arterial pressures. Transcatheter treatment is feasible, and results in resolution of cyanosis. Only continuing follow-up will show whether further collateralization occurs in time.
Canada↗
Contrast-enhanced MR angiography of pulmonary venous abnormalities in children.
BACKGROUND: Echocardiography and X-ray angiography have been considered as gold standards for evaluation of pulmonary venous abnormalities. However, each technique has its own limitations, such as limitation in visualization of the pulmonary veins within the lungs by echocardiography, and the invasive nature of and use of ionizing radiation in X-ray angiography. Contrast-enhanced MR angiography (MRA) is a fast noninvasive method of visualization of the vessels including the pulmonary arteries and veins. OBJECTIVES: To evaluate the utility of contrast-enhanced MRA in the evaluation of pulmonary venous abnormalities in pediatric patients and to compare its diagnostic accuracy with that of transthoracic echocardiography. MATERIALS AND METHODS: In 30 pediatric patients 31 contrast-enhanced MRA studies were performed for evaluation of pulmonary venous abnormalities. Each of 124 pulmonary veins was evaluated for site of connection, course within the lung, presence of obstruction, and topographic relationship with the adjacent structures. The findings of MRA were compared with echocardiographic findings for 116 veins in 29 studies in 28 patients. RESULTS: Contrast-enhanced MRA visualized 99% (123 of 124) of the pulmonary veins investigated, while echocardiography visualized 89% (103 of 116). Exact agreement was found between the two methods in 72% of the veins with a weighted kappa of 0.60 (0.47-0.73, 95% CI). Echocardiography failed to diagnose an abnormal connection in 2 of 15 pulmonary veins, a discrete stenosis in 2 of 19 veins, and diffuse hypoplasia in 10 of 14 veins. In 29% of patients, MRA made the uncertain echocardiographic findings clear. In another 29%, MRA provided a new diagnosis. CONCLUSIONS: Contrast-enhanced MRA is a powerful, safe, and accurate fast-imaging technique for the anatomical evaluation of pulmonary venous abnormalities. MRA may obviate the need for conventional X-ray angiography. Cardiac catheterization may be reserved for those patients in whom pulmonary vascular resistance needs to be determined.
Adolescent↗
MRI-based blood oxygen saturation measurements in infants and children with congenital heart disease.
BACKGROUND: Vessel oxygen saturation can be determined with MR oximetry using an in vivo measurement of signal decay (T2) and the calibration curve relating T2 to blood oxygen saturation (%HbO(2)), where: 1/T2=1/T2O+K (1-%HbO(2)/100)(2) and K is a constant parameter which correlates with measured fibrinogen levels. The ability to noninvasively measure %HbO(2) in cardiac chambers and vessels has enormous potential in children with congenital heart disease (CHD). OBJECTIVE: The purpose of the study was to prospectively characterize the T2-%HbO(2) relationship in infants where T2-%HbO(2) is the relationship between T2 and %HbO(2) (blood oxygen saturation) expressed by the equation given above, and to determine whether adult values for K and T2O (where T2O is the T2 of fully oxygenated blood) can be extrapolated to pediatric patients with CHD. A second objective was to apply this method to calculate the %HbO(2) in vivo using MR imaging in infants with CHD. MATERIALS AND METHODS: Fifteen patients with CHD undergoing cardiac catheterization (9 male; 6 female), median age 8 months, were recruited for the calibration study. T2O and K were measured directly from blood samples, compared with the values estimated from adult population statistics, and plotted against hematocrit and fibrinogen, respectively. In four studies of infants with CHD, T2 measurements were converted to %HbO(2) using the calibration curve. RESULTS: The T2-%HbO(2) relationship in infants correlated with the adult calibration statistics (1/T2O vs. hematocrit, r=0.77; K vs. fibrinogen, r=0.61). Our initial in vivo studies demonstrated that the MR oximetry reflected the expected oxygen saturations. CONCLUSION: Adult values for T2-%HbO(2) calibration can be used to measure blood oxygen saturation in vivo in children with CHD.
Blood Gas Analysis↗
Bronchial compression by posteriorly displaced ascending aorta in patients with congenital heart disease.
BACKGROUND: We encountered several patients with posteriorly displaced ascending aorta and bronchial compression associated with congenital heart disease. We describe the helical computed tomography (CT) findings and explore the mechanism of airway compression. METHODS: We retrospectively reviewed the clinical data and CT findings of 8 patients with posterior displacement of the ascending aorta. The bronchial stenosis was quantified on reformatted images perpendicular to the main-stem bronchi. On an axial image at the level of main bronchi, we measured depth of retrosternal space, interaortic distance, and aorto-spinal distance. To compare with control, we measured the same variables in 10 control patients. RESULTS: In 7 patients, the main bronchus on the side of the aortic arch was squeezed between the ascending and descending aorta and showed slit-like stenosis. The right pulmonary artery was elongated around the ascending aorta in 5 patients and showed slit-like stenosis in 3. Patients with posterior displacement had significantly larger retrosternal space, smaller interaortic distance, and smaller aorto-spinal distance than did the control group. Aortopexy was undertaken in 3 patients. Follow-up computed tomograms of 2 patients showed improvement. CONCLUSIONS: The posteriorly displaced ascending aorta may compress the main bronchus on the side of the aortic arch and right pulmonary artery against the descending aorta or spine. Even if the bronchial compression is mild with tolerable airway symptoms, these patients must be closely observed. When airway symptoms are severe, aortopexy should be considered.
Adolescent↗