Biomedical subjects
Publications and source records attributed to Shi-Joon Yoo.
We report the first case of double-barrelled aorta associated with tetralogy of Fallot and pulmonary atresia, and we discuss the difficulties in the terminology of this fascinating anomaly.
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OBJECTIVES: We described morphologic characteristics, particularly pulmonary anatomy, and determined the prevalence of definitive end states and their determinants in children with pulmonary atresia associated with ventricular septal defect (PAVSD). BACKGROUND: Pulmonary atresia associated with ventricular septal defect represents a broad morphologic spectrum that greatly influences management and outcomes. METHODS: From 1975 to 2004, 220 children with PAVSD presented to our institution. Blinded angiographic review (n = 171) characterized bronchopulmonary segment arterial supply. RESULTS: A total of 185 patients underwent surgery, and repair was definitive in 75%. Initial operations included systemic-pulmonary artery shunt in 57%, complete primary repair in 31%, or right ventricular outflow tract reconstruction in 12%. Based on angiographic review, 118 patients had simple PAVSD and 53 patients had PAVSD with major aortopulmonary collateral arteries (MAPCAs). Overall survival from initial operation was 71% at 10 years. Risk factors for death after initial operation included younger age at repair, earlier birth cohort, fewer bronchopulmonary segments supplied by native pulmonary arteries, and initial placement of a systemic-pulmonary artery shunt. Competing-risks analysis for initially palliated patients predicted that after 10 years, 68% achieved complete repair (with associated factors including later birth cohort and more bronchopulmonary segments supplied by native pulmonary arteries), 22% died without repair, and 10% remained alive without repair. Reoperations after complete repair occurred in 38 children (27%), with risk factors including older age at palliation, MAPCAs, and more segments supplied by collaterals. CONCLUSIONS: Outcomes in children with PAVSD have improved over time, and are better in completely repaired cases. Bronchopulmonary arterial supply is an important determinant of mortality, achievement of definitive repair, and post-repair reoperation.
Because there is a paucity of information regarding the diagnosis and outcomes of fetal heterotaxy syndrome (HS), this study sought to determine the spectrum of cardiac pathology, accuracy of diagnosis, and outcome of fetal HS. All cases of fetal HS encountered in the investigators' institution over a 10-year period through 2002 were identified. Prenatal and postnatal echocardiograms and medical records were reviewed. Seventy-one fetuses were diagnosed with HS, including 48 with left atrial isomerism (LAI) and 23 with right atrial isomerism (RAI). For LAI and RAI, most intracardiac lesions, the pulmonary venous connections, and superior vena caval anatomy were correctly diagnosed in utero (93%, 86%, and 77% accuracy, respectively), whereas hepatic venous connections and inferior vena caval-atrial connections in RAI were difficult to define (65% and 56% accuracy, respectively). Of 32 continued and followed pregnancies with LAI, 22 are currently alive at 48 +/- 30 months. Heart block and associated major extracardiac pathology were significantly more common in nonsurvivors with fetal LAI (p = 0.007 and 0.024, respectively). Outcomes were even worse for prenatally diagnosed RAI: of 14 continued pregnancies, only 3 are currently alive. In conclusion, fetal HS is associated with a broad spectrum of cardiac pathology, which can be diagnosed accurately in utero. Fetal LAI is associated with a mortality of 31%, with heart block and extracardiac pathology as primary risk factors for perinatal mortality. The outcome of prenatally diagnosed RAI is poor.
BACKGROUND: There are no large series describing the morphologic spectrum and the clinical outcomes of children with ductal origin of the distal pulmonary artery (PA). METHODS: Medical records were reviewed for all children presenting between 1970 and 2001. Angiograms were reviewed at presentation and at last available follow-up. RESULTS: Forty-five patients were identified with median presenting age of 14 days (range, birth to 6.5 years). Ductal origin of the distal PA occurred as an isolated finding in 16 patients (36%), with tetralogy of Fallot in 12 (27%), with pulmonary atresia-ventricular septal defect in 13 (29%), and with heterotaxy in 4 (9%). Diagnostic pulmonary venous wedge angiography was performed in 21 patients (47%). Surgical procedures were undertaken in 31 patients, and were initial systemic-ductal PA shunt in 13 patients, interposition graft in 6, direct anastomosis to the main PA in 2, ductal PA banding in 2, unifocalization of the ductal PA with complete or staged pulmonary atresia-ventricular septal defect repair in 7, and heart transplantation in 1 patient. Surgical revision was required in 3 patients and catheter interventions in 12 patients. Overall 20-year survival was 70% and was improved among patients without congestive heart failure at presentation (p = 0.08, hazard ratio: 2.81). Reconstruction of the ductal PA decreased the prevalence of pulmonary parenchymal hypoplasia (p < 0.001) and scoliosis at last available follow-up. CONCLUSIONS: Ductal origin of the distal PA is associated with important multisystem morbidity and mortality. Early diagnosis and repair of the ductal PA, especially in children presenting with pulmonary overcirculation, may improve outcomes.
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We report a case in which a meandering right pulmonary vein connecting to the left atrium is associated with hypoplasia of the right lung, horseshoe lung, abnormal pulmonary lobation, and abnormal branching of the pulmonary arteries. We discuss its relationship to the so-called scimitar variant, and to the scimitar syndrome itself.
We report an unusual case in which the peripheral part of the otherwise normal left lung was supplied by major systemic arteries arising from the left subclavian, internal mammary and coeliac arteries. Unlike most cases with systemic arterial supply to a normal or sequestered lung, where the systemic arterial branches get access to the lung through the pulmonary hilum or inferior pulmonary ligament, in our patient the systemic arterial branches entered the lung through the transpleural routes.
BACKGROUND: Infants are prone to obstruction of the upper airway during general anesthesia. Continuous positive airway pressure (CPAP) is often used to prevent or treat anesthesia-induced airway obstruction. The authors studied the interaction of propofol anesthesia and CPAP on airway caliber in infants using magnetic resonance imaging. METHODS: Nine infants undergoing elective magnetic resonance imaging of the brain were studied. Head position was standardized. Spin echo magnetic resonance images of the airway were acquired at the level of the soft palate, base of the tongue, and tip of the epiglottis. Four sets of images were acquired in sequence: (1) during light propofol anesthesia at an infusion rate of 80 microg . kg(-1) . min(-1), (2) after increasing the depth of propofol anesthesia by administering a bolus dose (2.0 mg/kg) and increasing the infusion rate to 240 microg . kg(-1) . min(-1), (3) during continued infusion of 240 microg . kg(-1). min propofol and application of 10 cm H2O CPAP, and (4) after removal of CPAP and continued infusion of 240 microg . kg(-1). min propofol. RESULTS: Increasing depth of propofol anesthesia decreased airway caliber at each anatomical level, predominantly due to anteroposterior narrowing. Application of CPAP completely reversed the propofol-induced decrease in airway caliber, primarily by increasing the transverse dimension. CONCLUSIONS: Airway narrowing with increasing depth of propofol anesthesia results predominantly from a reduction in anteroposterior dimension, whereas CPAP acts primarily to increase the transverse dimension. Although airway caliber during deep propofol anesthesia and application of CPAP was similar to that during light propofol anesthesia, there were significant configurational differences.
BACKGROUND: Previous studies in humans suggest that inhibition of upper airway muscle activity is independent of the dose of inhalational anesthesia. Whether a dose-independent relation applies to changes in airway caliber is unknown. The authors sought to evaluate the configurational changes that lead to upper airway narrowing during inhalational anesthesia with sevoflurane and to determine whether these changes are dose dependent within a clinically relevant dose range. METHODS: Fifteen children undergoing elective magnetic resonance imaging of the brain were studied. Magnetic resonance images of the upper airway were acquired at sevoflurane concentrations of 0.5, 1.0, and 1.5 minimum alveolar concentration (MAC), administered in random sequence. At least 15 min was allowed for equilibration of inspired and alveolar partial pressures of sevoflurane. Images were acquired in early expiration at the level of the soft palate, base of the tongue, and tip of the epiglottis. Airway cross-sectional area (CSA), anteroposterior, and transverse dimension were determined using image-analysis software. RESULTS: At each anatomical level, pharyngeal CSA decreased progressively with increasing depth of sevoflurane anesthesia (P < 0.001). Increasing the sevoflurane concentration from 0.5 to 1.0 MAC reduced airway CSA by 13-18%, and a further increase to 1.5 MAC resulted in an overall 28-34% reduction in CSA. The reduction in CSA was predominantly due to a decrease in anteroposterior dimension. CONCLUSIONS: Increasing the depth of sevoflurane anesthesia resulted in a relatively uniform reduction in pharyngeal caliber at each anatomical level studied. The effect of sevoflurane on upper airway caliber is dose dependent.
We present unusual imaging findings of petrified ears in a 9-year-old girl with Keutel syndrome. The patient presented for a temporal bone study for hearing loss. CT scan showed middle and inner ear abnormalities along with extensive and unsuspected calcification of the external ears and ossicular ligaments. On further investigation, the patient was found to have diffuse cartilage calcification in the larynx and tracheobronchial tree, brachytelephalangism and peripheral pulmonary stenosis suggestive of Keutel syndrome. Confirmation was obtained by mutation analysis.
Right aortic arch with isolation of the left subclavian artery is a rare disorder. In this entity, the left subclavian artery has its origin from the pulmonary artery via the ductus arteriosus. We report an infant with an unbalanced atrioventricular septal defect, right aortic arch, bilateral ductus arteriosi and an isolated left subclavian artery. This infant also had chromosome 22q11 deletion. The origin and course of the isolated subclavian artery were well-demonstrated using contrast-enhanced 3-D magnetic resonance angiography. This non-invasive diagnostic modality can accurately reveal detailed mediastinal vascular anatomy in a young infant and allows diagnosis of aberrant vascular connections.
BACKGROUND: Non-compaction of the left ventricular myocardium is an important cause of cardiomyopathy. There is no clear consensus about its diagnostic criteria or the diagnostic test of choice. MRI is increasingly used in the pediatric cardiac field because of its superior and objective image quality. OBJECTIVE: To compare the echocardiographic and MRI findings in four patients with recently diagnosed ventricular non-compaction. MATERIALS AND METHODS: We compared the extent of myocardial involvement shown at MRI and echocardiography in four individuals, two patients with echocardiographic diagnosis of left ventricular non-compaction, and two family members of one of the patients. RESULTS: In all patients, MRI showed wider area of involvement than echocardiography. A definite diagnosis was entertained in only two patients by echocardiography but in all by MRI. Cine imaging was diagnostic of the disease in all patients. Black-blood pool imaging with double-inversion recovery sequence also helped to visualize the abnormal areas by showing slow flow artifacts in the four- and two-chamber images. CONCLUSION: MRI provided better delineation of the extent of the abnormal trabeculation in patients with non-compaction of the left ventricular myocardium. It was particularly useful when the myocardial involvement was subtle, as in the asymptomatic family members.
BACKGROUND: Hemodynamic changes within a stenosed pulmonary vein might not reflect the severity of the obstruction if redistribution of pulmonary artery flow occurs. OBJECTIVE: The purpose was to investigate flow changes in branch pulmonary arteries in the presence of pulmonary vein stenosis. MATERIALS AND METHODS: Twelve children (age range 3-180 months) who had undergone MRI for pulmonary vein stenosis were identified. The severity of vein stenosis was assessed from percentage diameter reduction. Pulmonary artery flow distribution was correlated with the severity of pulmonary vein stenosis. Nine of the patients had unilateral stenosis; three had bilateral involvement. RESULTS: Unilateral vein stenosis was associated with diastolic reversal in the ipsilateral branch pulmonary artery (mean flow reversal 12.3%, range 2.4-42%) and continuous diastolic forward flow in the contralateral pulmonary artery in seven of nine patients. Severe stenosis was associated with decreased systolic flow to the ipsilateral lung. The ratio of net forward flow through pulmonary arteries correlated well with the cross-sectional area ratio of pulmonary arteries (r=0.75, P=0.006). CONCLUSIONS: Severe pulmonary vein obstruction results in redistribution of pulmonary arterial flow. When investigating pulmonary vein stenosis by MR, an evaluation of the pulmonary arterial system should be included to assess the functional importance of an obstruction.
PURPOSE: To compare in vivo real-time Fourier velocity encoding (FVE), spectral-Doppler ultrasound, and phase-contrast (PC) magnetic-resonance (MR) imaging. MATERIALS AND METHODS: In vivo velocity spectra were measured in the suprarenal and infrarenal aorta and the hepatic segment of the inferior vena cava of eight normal volunteers using FVE, and compared to similar measurements using Doppler ultrasound and gated PC MR imaging. In vivo waveforms were compared qualitatively according to flow pattern appearance (number, shape, and position of velocity peaks) and quantitatively according to peak velocity. RESULTS: Good agreement was obtained between peak velocities measured in vitro using FVE and PC MR imaging (R(2) = 0.99, P = 2.10(-6), slope = 0.97 +/- 0.05). Qualitatively, the FVE and ultrasound measurements agreed closely in the majority of in vivo cases (excellent or good in 21/24 cases) while the PC MR method resolved fewer velocity peaks due to the inherent temporal averaging of cardiac-gated studies (excellent or good agreement with FVE in 13/24 cases). Quantitatively, the FVE measurement of peak velocity correlated strongly with both ultrasound (R(2) = 0.71, P = 2.10(-7), slope = 0.81 +/- 0.08) and PC MR (R(2) = 0.85, P = 2.10(-10), slope = 1.04 +/- 0.08). CONCLUSION: Real-time MR assessment of blood-flow velocity correlated well with spectral Doppler ultrasound. Such new methods may allow hemodynamic information to be acquired in vessels inaccessible to ultrasound or in patients for whom respiratory compensation is not possible.
PURPOSE: To describe the normal flow patterns in peripheral pulmonary vessels with phase-contrast (PC) magnetic resonance imaging (MRI). MATERIALS AND METHODS: Twelve healthy adults (age = 33 +/- 7 years) underwent cine PC MRI of the segmental and central pulmonary arteries and veins by means of a breath-held segmented k-space technique. Flow patterns were analyzed on time-velocity curves and compared between the peripheral and central vessels. RESULTS: The pulsatile flow patterns in the segmental arteries and veins were similar among individuals. When compared with the central pulmonary arteries, the segmental arteries had a delay in the systolic and diastolic flow velocity waves, and an increased magnitude of the diastolic peaks, in relation to the systolic peaks. A prominent notch was present during the deceleration phase of the systolic flow velocity wave in 79% of the segmental arteries investigated. The segmental veins showed a typical pulmonary venous flow pattern, as seen in the central veins, with similar systolic-to-diastolic peak velocity ratios. CONCLUSION: Noninvasive evaluation of blood flow in intraparenchymal pulmonary vessels is feasible with PC MRI. This first description of normal flow patterns in segmental pulmonary arteries and veins can serve as basis for further investigation in the setting of altered pulmonary blood flows.
Contrast kinetics were studied in the main pulmonary artery (MPA) and ascending aorta (AAo) of 12 children with congenital heart disease. This information was used to optimize the timing of data acquisition for contrast-enhanced MR angiography in these vessels. To reduce contrast-agent dosage in these fragile patients, contrast enhancement was measured during routine diagnostic 3D magnetic resonance (MR) angiography instead of using test-bolus methods. This was possible by acquiring 2D cross-sectional images of the MPA and AAo during the 3D scan. Time-to-peak in the MPA and AAo was 4.9 +/- 2.2 and 6.1 +/- 2.2 s, respectively, while the transit time between the two vessels was 4.5 +/- 0.6 s. A point-spread-function analysis showed that intravascular signal strength was maximized if data acquisition began 4.7 +/- 2.3 s after the first arrival of contrast in the MPA and 5.6 +/- 2.3 s in the AAo. Little signal loss and artifact resulted when longer acquisition delays were used because contrast-agent clearance was slow. Based on these results, MR angiography of both the MPA and the AAo in children with congenital heart disease can be performed using elliptic-centric k-space sampling and a trigger delay of 7.9 s after contrast arrival in the AAo (i.e., time-to-peak signal strength in the AAo plus one SD to account for intersubject variability).
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