Margaret M. Samyn

Guidelines and protocols for cardiovascular magnetic resonance in children and adults with congenital heart disease: SCMR expert consensus group on congenital heart disease.

Cardiovascular magnetic resonance (CMR) has taken on an increasingly important role in the diagnostic evaluation and pre-procedural planning for patients with congenital heart disease. This article provides guidelines for the performance of CMR in children and adults with congenital heart disease. The first portion addresses preparation for the examination and safety issues, the second describes the primary techniques used in an examination, and the third provides disease-specific protocols. Variations in practice are highlighted and expert consensus recommendations are provided. Indications and appropriate use criteria for CMR examination are not specifically addressed.

A review of the complementary information available with cardiac magnetic resonance imaging and multi-slice computed tomography (CT) during the study of congenital heart disease.

AbstractThe incidence of congenital heart disease is approximately 4–6 per 1000 new births; however, the number of people living with congenital heart disease (CHD) is increasing, because of improved diagnosis, medical, and surgical management. While echocardiography continues to be the mainstay of non-invasive imaging, cardiac MRI (cMRI) and computed tomography (CT) have taken on increasing roles in the diagnosis of congenital heart disease in infants, children, and importantly, adults who may have limited echocardiographic windows, especially if post-operative. Cardiac MRI and multi-slice CT can complement the diagnostic information obtained by echocardiography and invasive cardiac catheterization. Post-operative imaging of CHD is especially enhanced by the spin echo MRI techniques, while gradient cine echo MRI imaging allows functional information that is not encumbered by geometric assumptions. Phase contrast (velocity encoding) cardiac MRI data can provide information about flow, allowing accurate determination of regurgitation and shunt volume. Gadolinium enhanced cMRI or three-dimensional reconstructed images from multi-slice CT angiography allow excellent delineation of vascular structures in complex heart disease. Coronary imaging, while possible with both modalities, appears more facile with fast CT imaging. This article reviews the literature to provide an assessment of the special techniques and considerations needed during the conduct of cardiac MRI/MRA and multi-slice CT examinations during the diagnosis of congenital heart disease in pediatric and adult patients.

Range of ventricular dimensions and function by steady‐state free precession cine MRI in repaired tetralogy of Fallot: Right ventricular outflow tract patch vs. conduit repair

To characterize the range of biventricular size and function evaluated by steady‐state free precession (SSFP) cine magnetic resonance (MR) in a large cohort of patients with repaired tetralogy of Fallot (TOF), and to compare these measurements in those with a right ventricular outflow tract (RVOT) patch vs. a right ventricle‐to‐pulmonary artery (RV‐PA) conduit.

COMPUTATIONAL SIMULATIONS DEMONSTRATE ALTERED WALL SHEAR STRESS IN AORTIC COARCTATION PATIENTS TREATED BY RESECTION WITH END-TO-END ANASTOMOSIS

BACKGROUND Atherosclerotic plaque in the descending thoracic aorta (dAo) is related to altered wall shear stress (WSS) for normal patients. Resection with end-to-end anastomosis (RWEA) is the gold standard for coarctation of the aorta (CoA) repair, but may lead to altered WSS indices that contribute to morbidity. METHODS Computational fluid dynamics (CFD) models were created from imaging and blood pressure data for control subjects and age- and gender-matched CoA patients treated by RWEA (four males, two females, 15 ± 8 years). CFD analysis incorporated downstream vascular resistance and compliance to generate blood flow velocity, time-averaged WSS (TAWSS), and oscillatory shear index (OSI) results. These indices were quantified longitudinally and circumferentially in the dAo, and several visualization methods were used to highlight regions of potential hemodynamic susceptibility. RESULTS The total dAo area exposed to subnormal TAWSS and OSI was similar between groups, but several statistically significant local differences were revealed. Control subjects experienced left-handed rotating patterns of TAWSS and OSI down the dAo. TAWSS was elevated in CoA patients near the site of residual narrowings and OSI was elevated distally, particularly along the left dAo wall. Differences in WSS indices between groups were negligible more than 5 dAo diameters distal to the aortic arch. CONCLUSIONS Localized differences in WSS indices within the dAo of CoA patients treated by RWEA suggest that plaque may form in unique locations influenced by the surgical repair. These regions can be visualized in familiar and intuitive ways allowing clinicians to track their contribution to morbidity in longitudinal studies.

Pediatric Atorvastatin in Diabetes Trial (PADIT): A Pilot Study to Determine the Effect of Atorvastatin on Arterial Stiffness and Endothelial Function in Children with Type 1 Diabetes Mellitus

Fifty-one children with type 1 diabetes mellitus (DM1) participated in a double blinded, randomized, cross-over pilot study to determine whether 12 weeks of daily atorvastatin (20 mg daily) would reduce arterial stiffness and improve endothelial function. Secondary analysis demonstrated potential reduction of arterial stiffness following atorvastatin therapy (p = 0.06). Additional long-term prospective studies with larger numbers of patients are needed.

INCLUDING AORTIC VALVE MORPHOLOGY IN COMPUTATIONAL FLUID DYNAMICS SIMULATIONS: INITIAL FINDINGS AND APPLICATION TO AORTIC COARCTATION

Computational fluid dynamics (CFD) simulations quantifying thoracic aortic flow patterns have not included disturbances from the aortic valve (AoV). 80% of patients with aortic coarctation (CoA) have a bicuspid aortic valve (BAV) which may cause adverse flow patterns contributing to morbidity. Our objectives were to develop a method to account for the AoV in CFD simulations, and quantify its impact on local hemodynamics. The method developed facilitates segmentation of the AoV, spatiotemporal interpolation of segments, and anatomic positioning of segments at the CFD model inlet. The AoV was included in CFD model examples of a normal (tricuspid AoV) and a post-surgical CoA patient (BAV). Velocity, turbulent kinetic energy (TKE), time-averaged wall shear stress (TAWSS), and oscillatory shear index (OSI) results were compared to equivalent simulations using a plug inlet profile. The plug inlet greatly underestimated TKE for both examples. TAWSS differences extended throughout the thoracic aorta for the CoA BAV, but were limited to the arch for the normal example. OSI differences existed mainly in the ascending aorta for both cases. The impact of AoV can now be included with CFD simulations to identify regions of deleterious hemodynamics thereby advancing simulations of the thoracic aorta one step closer to reality.

Should a bicuspid aortic valve be replaced in the presence of subvalvar or supravalvar aortic stenosis

BACKGROUND A bicuspid aortic valve is commonly associated with other levels of left ventricular outflow tract obstruction. Providing the bicuspid aortic valve is competent and nonobstructive, repair of subvalvar or supravalvar stenosis usually focuses on the obstructive lesions, leaving the valve in situ. The aim of this report was to examine the impact of a bicuspid aortic valve on the risk of reoperation for patients undergoing operation for subvalvar or supravalvar aortic stenosis. METHODS Since 1976, 47 patients with supravalvar or subvalvar aortic stenosis have undergone repair. The median follow-up is 5.1 years (range, 2 months to 20.1 years). Sixteen patients (34%) had a bicuspid aortic valve that was competent and nonobstructive, and 31 (66%) had a tricuspid aortic valve. RESULTS Reoperation was required in 9 patients (56%) with a bicuspid aortic valve, in each involving aortic valve replacement with an autograft (3), homograft (2), or prosthesis (4). Six patients (19%) with a tricuspid aortic valve required reoperation, yet only 1 required aortic valve replacement. The freedom from valve replacement was 43% (70% confidence interval, 31% to 55%) in the bicuspid aortic valve group versus 100% (70% confidence interval, 94% to 99.5%) in the tricuspid group at 5 years (p = 0.0001). The freedom from any reoperation at 5 years was 43% (70% confidence interval, 31% to 55%) in patients with a bicuspid aortic valve versus 86% (70% confidence interval, 80% to 93%) in the tricuspid group (p = 0.02). CONCLUSIONS The data suggest that patients with subvalvar or supravalvar aortic stenosis and a bicuspid valve may be better palliated with a more definitive operation such as the Ross or Ross-Konno procedure.

An institutional review of the value of computed tomographic angiography in the diagnosis of congenital cardiac malformations.

The ultra-fast, thin-cut computerised tomographic angiogram is an efficient method to diagnose extracardiac lesions associated with congenital cardiac disease. For the purposes of this review, we evaluated various facets of the technique as used in 30 patients who were referred for diagnosis of congenital cardiac disease. The technique had high diagnostic accuracy, with a sensitivity of 93 percent in 15 of these patients referred for either interventional catheterisation or surgery. There were no immediate side-effects associated with the scanning procedure. The scan was also found to be more cost-effective as compared to an alternative noninvasive modality for imaging modality, namely magnetic resonance imaging. The angiographic technique, however, does expose the child to between 2 and 2.5 rems of radiation, despite the short period of scanning, of 10 plus or minus 2 seconds.

Olfactory bulbectomy prevents short photoperiod-induced anestrus in female golden hamsters

When female golden hamsters are maintained on a photoperiod of less than 12.5 h of light per day, they go into a pineal gland-induced anestrus in 6-10 weeks. This acyclicity is similar in certain respects to the testicular regression which occurs in male golden hamsters maintained on a short photoperiod. A recent study has indicated that pre-pubertal olfactory bulbectomy (BX) will prevent the testicular regression in adult male hamsters exposed to a short photoperiod. The present study tested the effect of pre-pubertal or adult BX on the anestrus associated with maintenance of adult female golden hamsters on short photoperiod. In Expt. 1, hamsters were pre-pubertally sham BX (SH) or BX (23-25 days of age) and then maintained on LD 14:10 or LD 6:18 for 15 weeks. In Expt. 2, hamsters were SH or BX as adults (63-65 days of age) and maintained on LD 6:18 for 13 weeks. The estrous cycles of all animals were monitored on a daily basis. In Expt. 1, all animals on LD 14:10 had regular estrous cycles for the duration of the study. Sixty percent of the SH group on LD 6:18 became anestrous, whereas 87.5% of the BX group on LD 6:18 continued having regular cycles. In Expt. 2, 80% of the SH group became anestrous while 90% of the BX group continued having regular estrous cycles. The possible mechanisms whereby BX affects the cyclicity of female hamsters is discussed. The fact that BX resulted in increased morning gonadotropin levels and ovarian weight in animals on LD 14:10, as well as in the hamsters on short photoperiod, suggests that there is a relationship between the olfactory bulb and the reproductive system that is independent of the photoperiod, in addition to more dramatic effects of olfaction on reproduction in animals on a short photoperiod.

The Pediatric Barriers to a Healthy Diet Scale

The Pediatric Barriers to a Healthy Diet Scale (PBHDS) is a 17-item measure developed to assess barriers to healthy dietary habits as perceived by overweight and obese children and adolescents. This study presents preliminary descriptive, psychometric, and factor analytic data for the PBHDS based on a sample of 171 overweight and obese children. The measure provides a Total Barriers score, as well as subscale scores for Access and Desire factors. The Total Barriers score and subscale scores demonstrate adequate internal consistency and convergent validity. Use of the PBHDS can have significant implications for clinicians and researchers involved in program development and the treatment of children struggling with adherence to dietary treatment recommendations.