[Show abstract][Hide abstract] ABSTRACT: Patients with single ventricle can develop aortic-to-pulmonary collaterals (APCs). Along with systemic-to-pulmonary artery shunts, these structures represent a direct pathway from systemic to pulmonary circulations, and may limit cerebral blood flow (CBF). This study investigated the relationship between CBF and APC flow on room air and in hypercarbia, which increases CBF in patients with single ventricle.
106 consecutive patients with single ventricle underwent 118 cardiac magnetic resonance (CMR) scans in this cross-sectional study; 34 prior to bidirectional Glenn (BDG) (0.50±0.30 years old), 50 prior to Fontan (3.19±1.03 years old) and 34 3-9 months after Fontan (3.98±1.39 years old). Velocity mapping measured flows in the aorta, cavae and jugular veins. Analysis of variance (ANOVA) and multiple linear regression were used. Significance was p<0.05.
A strong inverse correlation was noted between CBF and APC/shunt both on room air and with hypercarbia whether CBF was indexed to aortic flow or body surface area, independent of age, cardiopulmonary bypass time, Po2 and Pco2 (R=-0.67--0.70 for all patients on room air, p<0.01 and R=-0.49--0.90 in hypercarbia, p<0.01). Correlations were not different between surgical stages. CBF was lower, and APCs/shunt flow was higher prior to BDG than in other stages.
There is a strong inverse relationship between CBF and APC/shunt flow in patients with single ventricle throughout surgical reconstruction on room air and in hypercarbia independent of other factors. We speculate that APC/shunt flow may have a negative impact on cerebral development and neurodevelopmental outcome. Interventions on APC may modify CBF, holding out the prospect for improving neurodevelopmental trajectory.
Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
[Show abstract][Hide abstract] ABSTRACT: There is an established association between tetralogy of Fallot and partial anomalous pulmonary venous connections. This association is important because surgically repaired tetralogy patients have increased risk of right heart failure. We hypothesize that partial anomalous venous connections increase right ventricular volumes and worsen right ventricular failure.
We reviewed cardiac MRI exams performed at a tertiary pediatric hospital from January 2005 to January 2014. We identified patients with repaired tetralogy and unrepaired partial anomalous pulmonary venous connection. We used age- and gender-matched repaired tetralogy patients without partial anomalous pulmonary venous connection as controls. We analyzed the MRI results and surgical course and performed comparative statistics to identify group differences.
There were eight patients with repaired tetralogy and unrepaired partial anomalous pulmonary venous connection and 16 controls. In all cases, the partial anomalous pulmonary venous connection was not detected on preoperative echocardiography. There were no significant differences in surgical course and body surface area between the two groups. Repaired tetralogy patients with unrepaired partial anomalous pulmonary venous connection showed significantly higher indexed right ventricular end diastolic volume (149 ± 33 mL/m(2) vs. 118 ± 30 mL/m(2)), right ventricle to left ventricle size ratios (3.1 ± 1.3 vs. 1.9 ± 0.5) and a higher incidence of reduced right ventricular ejection fraction compared to controls (3/8 vs. 0/16).
Repaired tetralogy of Fallot with unrepaired partial anomalous pulmonary venous connection is associated with reduced right ventricular ejection fraction and more significant right ventricular dilation.
[Show abstract][Hide abstract] ABSTRACT: In Bi-directional Glenn (BDG) physiology, the superior systemic circulation and pulmonary circulation are in series. Consequently, only blood from the superior vena cava is oxygenated in the lungs. Oxygenated blood then travels to the ventricle where it is mixed with blood returning from the lower body. Therefore, incremental changes in oxygen extraction ratio (OER) could compromise exercise tolerance. In this study, the effect of exercise on the hemodynamic and ventricular performance of BDG physiology was investigated using clinical patient data as inputs for a lumped parameter model coupled with oxygenation equations. Changes in cardiac index, Qp/Qs, systemic pressure, oxygen extraction ratio and ventricular/vascular coupling ratio were calculated for three different exercise levels. The patient cohort (n=29) was sub-grouped by age and pulmonary vascular resistance (PVR) at rest. It was observed that the changes in exercise tolerance are significant in both comparisons, but most significant when sub-grouped by PVR at rest. Results showed that patients over 2 years old with high PVR are above or close to the upper tolerable limit of OER (0.32) at baseline. Patients with high PVR at rest had very poor exercise tolerance while patients with low PVR at rest could tolerate low exercise conditions. In general, ventricular function of SV patients is too poor to increase CI and fulfill exercise requirements. The presented mathematical model provides a framework to estimate the hemodynamic performance of BDG patients at different exercise levels according to patient specific data.
Published by Elsevier Ltd.
Journal of Biomechanics 04/2015; 48(10). DOI:10.1016/j.jbiomech.2015.03.034 · 2.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The authors’ reply We read with interest the response1 to our study.2 The authors speculate: “What if indexed power loss (iPL) is dependent on body surface area (BSA)?” We wish to make the following points in response: The data extracted from our paper2 that includes 30 patients shows no statistically significant correlation (p=0.167) between iPL and BSA (see online supplementary figure). This clarifies the speculation and supports our conclusion: ‘iPL correlates with exercise capacity’. We believe this is not surprising given …
[Show abstract][Hide abstract] ABSTRACT: -Patients with repaired tetralogy of Fallot (TOF) experience variable outcomes for reasons that are incompletely understood. We hypothesize that genetic variants contribute to this variability. We sought to investigate the association of 22q11.2 deletion status with clinical outcome in patients with repaired TOF.
-We performed a cross sectional study of TOF subjects who were tested for 22q11.2 deletion, and underwent cardiac magnetic resonance (CMR), exercise stress test (EST) and review of medical history. We studied 165 subjects (12.3 ± 3.1 years), of which 30 (18%) had 22q11.2 deletion syndrome (22q11.2DS). Overall, by CMR the right ventricular (RV) ejection fraction was 60±8%, pulmonary regurgitant fraction 34±17%, and RV end-diastolic volume 114±39 cc/m(2). On EST, maximum oxygen consumption (mVO2) was 76±16% predicted. Despite comparable RV function and pulmonary regurgitant fraction, on EST the 22q11.2DS had significantly lower percent predicted: forced vital capacity (61.5 ± 16 vs. 80.5 ± 14, p< 0.0001); mVO2 (61±17 vs. 80±12, p<0.0001); and work (64±18 vs. 86±22, p=0.0002). Similarly, the 22q11.2DS experienced more hospitalizations (6.5 [5; 10] vs. 3 [2; 5], p<0.0001), saw more specialists (3.5 [2; 9] vs. 0 [0; 12], p<0.0001) and used one or more medications (67 vs. 34%, p <0.001).
-22q11.2DS is associated with restrictive lung disease, worse aerobic capacity, and increased morbidity, and may explain some of the clinical variability seen in TOF. These findings may provide avenues for intervention to improve outcomes, and should be re-evaluated longitudinally as these associations may become more pronounced with time.
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVE. Anomalous left coronary artery from the inappropriate aortic sinus with intraseptal course is generally benign but can be confused on imaging studies with the potentially lethal interarterial, intramural anomalous left coronary artery. The purpose of this study was to assess normal ostial morphologic features and intraseptal course using cardiac MRI and CT in pediatric patients with intraseptal anomalous left coronary artery. MATERIALS AND METHODS. A retrospective review was conducted of the medical records of 14 children with the diagnosis of intraseptal anomalous left coronary artery between November 2009 and March 2013. Coronary artery origin and course were evaluated with cardiac MRI or CT, and 3D assessment of coronary ostial morphologic features was performed with virtual angioscopy. RESULTS. The patient ages ranged from 5 to 18 years at diagnosis; 10 (71.4%) were boys. The right and left coronary origins were the right sinus of Valsalva as a common origin (n = 9) or a single coronary artery (n = 5). Anomalous intraseptal left main coronary was found in 13 patients, and one patient had anomalous left anterior descending with retroaortic circumflex coronary artery. Anomalous coronary ostia were round and without stenosis in all studies. The anomalous vessel was identified with echocardiography, but the anomalous left coronary artery was not delineated, and a normal ostium was not adequately portrayed in any instance. CONCLUSION. By use of cardiac MRI and CT, the anomalous course of round coronary ostia was confirmed and visualized in a pediatric cohort with intraseptal anomalous left coronary artery. The data provide the basis for understanding the benign clinical course and showing that surgery is unnecessary for this coronary anomaly.
American Journal of Roentgenology 01/2015; 204(1):W104-9. DOI:10.2214/AJR.14.12953 · 2.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Utilization of cardiovascular magnetic resonance (CMR) is limited in young children because of the need for sedation or general anesthesia (GA). It has been previously shown that CMR can be performed without sedation or GA in young infants who are prone to fall asleep after being fed and swaddled. The purpose of this study was to prospectively prove the feasibility of the feed-and-sleep CMR technique in larger cohorts in the two institutions where the technique was initially developed. This was a prospective dual-center cohort study over a two-year period. All infants younger than 6 months old with complex congenital cardiovascular anomaly who required CMR were recruited for this study. The exclusion criteria included mechanical ventilation, oxygen dependence, feeding difficulties, and any contraindication to CMR. The feed-and-sleep study was performed by fasting the infant for a period of 4 h prior to the scan, placing the infant in a vacuum immobilizer, and feeding the infant just prior to the CMR. The CMR sequences were prioritized to target the area of most importance first. A study was considered complete and diagnostic if the clinical question was answered. A total of 60 infants (39 from center A and 21 from center B) were recruited for this study, 32 male and 28 female, ages ranging from 1 to 177 days (50 ± 54). The CMR studies were diagnostic and answered the clinical questions in all patients. All infants tolerated the procedure well, and no complications were noted in any of the patients. The CMR duration ranged between 4-132 minutes (45 ± 21). The feed-and-sleep approach in selected patients obviates the need of sedation or GA for CMR in infants younger than 6 months old. Therefore, CMR can be utilized whenever echocardiography fails to provide the complete information required for the patients' management.
[Show abstract][Hide abstract] ABSTRACT: Pulmonary insufficiency (PI) is associated with right ventricular (RV) dilation, dysfunction, and exercise intolerance in patients with tetralogy of fallot (TOF). We sought to compare RV function and exercise performance in patients with valvar pulmonary stenosis (VPS) following pulmonary balloon valvuloplasty to those with repaired TOF with similar degrees of PI. We performed a cross-sectional study of patients with VPS and TOF. Cardiac magnetic resonance (CMR) and exercise stress test were performed. Subjects were matched by time from initial procedure and severity of PI using propensity scores. After matching, there were 16 patients with VPS and 16 with TOF for comparison, with similar demographics. Time from initial procedure was 14 years (12-16), p = 0.92, and pulmonary regurgitant fraction was 19 % (6-31), p = 0.94, Patients with TOF had lower ejection fraction [58 % (53-66) vs. 65 % (60-69), p = 0.04] and more RV hypertrophy [69 g/m(2) (52-86) vs. 44 g/m(2) (32-66), p = 0.04] compared to those with VPS. Aerobic capacity was worse in patients with TOF [68 ± 19 % mVO2 (56-84) vs. 82 ± 9.2 % (74-89) in VPS, p = 0.01], with a trend for less habitual physical activity [0.9 (0-12) vs. 8 h/week (4-12), p = 0.056], respectively. With similar degrees of PI, patients with TOF demonstrate worse RV function and aerobic capacity as compared to patients with just VPS. Habitual exercise may in part explain differences in exercise performance and should be further explored.
[Show abstract][Hide abstract] ABSTRACT: The American College of Cardiology (ACC) participated in a joint project with the American Society of Echocardiography, the Society of Pediatric Echocardiography, and several other subspecialty societies and organizations to establish and evaluate Appropriate Use Criteria (AUC) for the initial use of outpatient pediatric echocardiography. Assumptions for the AUC were identified, including the fact that all indications assumed a first-time transthoracic echocardiographic study in an outpatient setting for patients without previously known heart disease. The definitions for frequently used terminology in outpatient pediatric cardiology were established using published guidelines and standards and expert opinion. These AUC serve as a guide to help clinicians in the care of children with possible heart disease, specifically in terms of when a transthoracic echocardiogram is warranted as an initial diagnostic modality in the outpatient setting. They are also a useful tool for education and provide the infrastructure for future quality improvement initiatives as well as research in healthcare delivery, outcomes, and resource utilization. To complete the AUC process, the writing group identified 113 indications based on common clinical scenarios and/or published clinical practice guidelines, and each indication was classified into 1 of 9 categories of common clinical presentations, including palpitations, syncope, chest pain, and murmur. A separate, independent rating panel evaluated each indication using a scoring scale of 1 to 9, thereby designating each indication as "Appropriate" (median score 7 to 9), "May Be Appropriate" (median score 4 to 6), or "Rarely Appropriate" (median score 1 to 3). Fifty-three indications were identified as Appropriate, 28 as May Be Appropriate, and 32 as Rarely Appropriate.
Journal of the American College of Cardiology 11/2014; 64(19):2039-2060. DOI:10.1016/j.jacc.2014.08.003 · 15.34 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background
Radiation exposure in the pediatric population may increase the risk of future malignancy. Children with congenital heart disease who often undergo repeated catheterizations are at risk. One possible strategy to reduce radiation is to use X-ray Magnetic Resonance Fusion (XMRF) to facilitate cardiac catheterization. Methods
Catheterization data of patients who underwent diagnostic XMRF procedures between January 1, 2009 and February 1, 2012 were reviewed. Cases were matched 1:1 to contemporary controls who did not undergo XMRF based on weight and diagnosis and were compared in radiation exposure, contrast dose, and procedural and anesthesia times. ResultsForty-four matched pairs were included. Baseline demographics were similar in both groups. Patients in the XMRF group had lower indices of radiation exposure measured by fluoroscopy time (14 vs. 16.4 vs. P=0.047), dose-area product from fluoroscopy (513.2 vs. 589.1 mu Gym(2), P=0.042), total dose-area product (625.8 vs. 995.2 mu Gym(2), P=0.027), and total air kerma dose (94.5 vs. 153.8 mGy, P=0.017). There was also a significant reduction in contrast dose (2 vs. 3.3 cc/kg, P <0.001). Procedural time tended to be shorter in the XMRF group but anesthesia time was significantly longer. Conclusion
Select diagnostic cardiac catheterization cases that utilized XMRF used less radiation and contrast than similar cases where XMRF was not used. Future work is needed to determine whether similar benefits can be extended to other types of diagnostic and complex interventional procedures. (c) 2014 Wiley Periodicals, Inc.
[Show abstract][Hide abstract] ABSTRACT: Objective Elevated energy loss in the total cavopulmonary connection (TCPC) is hypothesised to have a detrimental effect on clinical outcomes in single-ventricle physiology, which may be magnified with exercise. This study investigates the relationship between TCPC haemodynamic energy dissipation and exercise performance in single-ventricle patients.
Methods Thirty consecutive Fontan patients with TCPC and standard metabolic exercise testing were included. Specific anatomies and flow rates at rest and exercise were obtained from cardiac MR (CMR) and phase-encoded velocity mapping. Exercise CMR images were acquired immediately following supine lower limb exercise using a CMR-compatible cycle ergometer. Computational fluid dynamics simulations were performed to determine power loss of the TCPC anatomies using in vivo anatomies and measured flows.
Results A significant negative linear correlation was observed between indexed power loss at exercise and (a) minute oxygen consumption (r=−0.60, p<0.0005) and (b) work (r=−0.62, p<0.0005) at anaerobic threshold. As cardiac output increased during exercise, indexed power loss increased in an exponential fashion (y=0.9671x3.0263, p<0.0001).
Conclusions This is the first study to demonstrate the relationship between power loss and exercise performance with the TCPC being one of the few modifiable factors to allow for improved quality of life. These results suggest that aerobic exercise tolerance in Fontan patients may, in part, be a consequence of TCPC power loss.
[Show abstract][Hide abstract] ABSTRACT: Background. Single-ventricle patients undergoing surgical reconstruction experience a high rate of brain injury. Incidental findings on preoperative brain scans may result in safety considerations involving hemorrhage extension during cardiopulmonary bypass that result in surgical postponement. Methods. Single-ventricle patients were studied with brain scans immediately preoperatively, as part of a National Institutes of Health study, and were reviewed by neuroradiology immediately before cardiopulmonary bypass. Results. Of 144 consecutive patients recruited into the project, 33 were studied before stage I (3.7 +/- 1.8 days), 34 before bidirectional Glenn (5.8 +/- 0.5 months), and 67 before Fontan (3.3 +/- 1.1 years) operations. Six operations (4.5%), 2 before stage I, 3 before bidirectional Glenn, and 1 before Fontan, were postponed because of concerning findings on brain magnetic resonance imaging. Five were due to unexpected incidental findings of acute intracranial hemorrhage, and 1 was due to diffuse cerebellar cytotoxic edema; none who proceeded to operation had these lesions. Prematurity and genetic syndromes were not present in any patients with a postponed operation. Four of 4 before bidirectional Glenn/Fontan with surgical delays had hypoplastic left heart syndrome compared with 44 of 97 who did not (p = 0.048). After observation and follow-up, all eventually had successful operations with bypass. Conclusions. Preoperative brain magnetic resonance imaging performed in children with single ventricles disclosed injuries in 4.5% leading to surgical delay; hemorrhagic lesions were most common and raised concerns for extension during the operation. The true risk of progression and need for delay of the operation due to heparinization associated with these lesions remains uncertain. (C) 2014 by The Society of Thoracic Surgeons
The Annals of Thoracic Surgery 08/2014; 98(5). DOI:10.1016/j.athoracsur.2014.05.079 · 3.63 Impact Factor