Vascular rings and their effect on tracheal geometry.

The major clinical impact of vascular rings in children is tracheal compression, which presents with recurrent symptoms of stridor, noisy breathing, and wheezing. This study tests the hypothesis that symptomatic patients have altered tracheal geometry compared to nonsymptomatic individuals. We retrospectively reviewed the tracheal dimensions (area and longest and shortest diameters) as visualized by magnetic resonance imaging from the cupola of the lung to the carina of 49 patients referred for evaluation of a vascular ring. The smallest dimension relative to the largest dimension (% of maximum) and the coefficient of variation (CoVar; standard deviation/mean) were assessed for each parameter. In all parameters measured (area and longest and shortest diameters), patients with symptoms due to vascular rings had significantly different values than patients without symptoms. The % of maximum was significantly smaller (area, 48.6 vs 62.1%; longest diameter, 41.0 vs 54.0%; shortest diameter, 45.0 vs 56.5%) and the CoVar was significantly greater (area, 0.26 vs 0.18; longest diameter, 0.31 vs 0.22; shortest diameter, 0.28 vs 0.19) in symptomatic individuals than in nonsymptomatic individuals. Patients with vascular rings who are symptomatic have significantly altered tracheal geometry compared to nonsymptomatic individuals. Magnetic resonance imaging is a useful tool for visualizing both the cardiovascular and the tracheal anatomy in patients with vascular rings and provides useful information for the management and care of these patients.

Noninvasive imaging of isolated persistent fifth aortic arch.

Persistent fifth aortic arch was suspected by echocardiography and confirmed by magnetic resonance imaging (MRI) in an infant with a heart murmur. Selected images including three dimensional reconstruction from MRI demonstrating this very rare congenital anomaly are presented.

A simplified approach for assessment of intracardiac baffles and extracardiac conduits in congenital heart surgery with two- and three-dimensional magnetic resonance imaging.

BACKGROUND: Intracardiac baffles and extracardiac conduits have been used in the reconstructive surgery of a broad spectrum of congenital cardiac malformations. Periodic evaluation of these structures may not lend itself readily to echocardiographic and angiographic imaging. The purpose of the study was to describe the experience of our institution with the use of magnetic resonance imaging (MRI) in evaluating conduits and baffles and to describe the simplified approach we developed to image these structures, which allows for grouping individual lesions into broad categories. METHODS AND RESULTS: We retrospectively reviewed our MRI experience in visualizing these structures from 1989-1996. One hundred thirty-nine patients underwent MRI to visualize 144 structures (116 baffles, 28 conduits). The 116 baffles included 86 Fontan, 16 Mustard, 6 Senning, 6 left ventricle to aorta, 1 right ventricle to aorta, and 1 pulmonary vein to left atrium baffle. The 28 conduits included 15 right ventricle to pulmonary artery, 4 left ventricular apical to aorta, 2 left ventricle to pulmonary artery, 3 aorta to aorta, 2 inferior vena cava to left atrium conduits, and 2 aortic root replacements. Of the 3 aortic-aortic conduits, 1 was in conjoined twins. Both inferior vena cava-left atrial conduits were in a Baffes procedure. An infectious mass missed by echocardiography in a right ventricle to pulmonary artery conduit was visualized by MRI. With multiplanar reconstruction, contiguous images were stacked atop each other and resliced to define the salient points of the anatomy. Three-dimensional reconstruction further added to this delineation. All structures were visualized successfully, and an assessment of obstruction was made. Multiple examples of conduit and baffle narrowing were diagnosed by spin echo and cine MRI and were subsequently confirmed by catheterization and surgical inspection. CONCLUSION: MRI, with multiplanar and 3-dimensional reconstruction, is useful in examining the variety of baffles and conduits used in congenital heart surgery. MRI can add to the care of patients whose echocardiographic windows or whose angiographically overlapping structures do not allow adequate delineation of conduits and baffles.

Patterns of right aortic arch and mirror-image branching of the brachiocephalic vessels without associated anomalies.

It is unusual to have a right aortic arch with mirror-image branching of the brachiocephalic vessels and no associated congenital cardiac anomalies. Pathogenetic factors of this anomaly, and associated development of the derivatives of the pharyngeal arches, have not been explored extensively. Eleven patients with a mirror-image right aortic arch and no intracardiac anomalies have undergone evaluation at our institution since 1987. Of these, 4 had stenosis (n = 2) or atresia (n = 2) of the proximal left pulmonary artery. These included 2 with bilateral ductus arteriosus. Six patients had a vascular ring formed by a ductus arteriosus or ligamentum arteriosum from the descending aorta to the left pulmonary artery. Six patients were evaluated for deletion within the DiGeorge critical region of chromosome 22q11. All 6 of the patients with a vascular ring underwent division of the ductus arteriosus or ligamentum through a left lateral thoracotomy. None of the patients with stenosis or atresia of the LPA have undergone intervention. Two of the 6 patients who underwent evaluation for chromosome 22q11 deletion were found to have the deletion. At a median follow-up of 7 years (15 months to 12 years), the patients who underwent division of the ring are all alive and asymptomatic. Two of these patients have undergone repeat magnetic resonance imaging, 1 of whom had mild residual tracheal compression. A right aortic arch with mirror-image branching of the brachiocephalic vessels and no associated intracardiac anomalies is extremely uncommon. We have observed two basic patterns of this lesion: (1) with associated abnormalities of the proximal left pulmonary artery, (2) with a vascular ring formed by a ductus arteriosus or ligamentum from the descending aorta to the left pulmonary artery. Pathogenetic considerations are explored, with a focus on flow-related vascular development and the role of deletions within chromosome 22q11.

Association of chromosome 22q11 deletion with isolated anomalies of aortic arch laterality and branching.

OBJECTIVES: The purpose of this study was to determine the frequency of chromosome 22q11 deletions in patients with isolated anomalies of the aortic arch and its branches. BACKGROUND: Chromosome 22q11 deletions are often present in patients with certain forms of congenital cardiovascular disease, including tetralogy of Fallot, truncus arteriosus and interruption of the aortic arch. Among patients with these anomalies, chromosome 22q11 deletion is more common in those with abnormal aortic arch laterality or branching. METHODS: We studied 66 patients with isolated anomalies of the aortic arch and no associated intracardiac defects for deletions within chromosome 22q11, using fluorescence in situ hybridization with the cosmid probe N25 (D22S75). Arch anomalies included: double aortic arch (n = 22); right aortic arch with aberrant left subclavian artery (n = 28); right aortic arch with mirror-image branching and a vascular ring formed by a left-sided ductus from the descending aorta (n = 5); right aortic arch with mirror-image branching and no vascular ring (n = 4); and left aortic arch with aberrant right subclavian artery (n = 7). In addition, four patients had a cervical aortic arch, four had aortic coarctation and six had hypoplasia/atresia of the proximal pulmonary arteries. RESULTS: Chromosome 22q11 deletions were found in 16 patients (24%) across the full spectrum of anomalies studied. Among the morphologic variables analyzed, only hypoplasia/atresia of the proximal pulmonary arteries correlated with the deletion (p = 0.03). Among patients with a double arch, the frequency of chromosome 22q11 deletion was higher in those with an atretic minor arch than it was in those with a patent minor arch (p = 0.02). CONCLUSIONS: Chromosome 22q11 deletion is associated with isolated anomalies of laterality or branching of the aortic arch in 24% of cases in our series. These findings should alert the clinician to consider deletion screening in patients with isolated anomalies of the aortic arch.

Evaluation and follow-up of patients with left ventricular apical to aortic conduits with 2D and 3D magnetic resonance imaging and Doppler echocardiography: A new look at an old operation.

BACKGROUND: Although the interposition of left ventricular apical to descending aorta conduits has diminished with the advent of the Ross-Konno operation, it remains a useful option. We reviewed our institutional experience imaging these conduits and tested the hypothesis that the gradient across the native left ventricular outflow tract (LVOT) by echocardiography correlated with the conduit gradient by cardiac catheterization. In a patient with an unobstructed conduit, no gradient should exist across the native LVOT. METHODS: This was a retrospective review of the echocardiography, cardiac catheterization, magnetic resonance imaging (MRI) data, and history of 9 patients with these conduits over an 8-year period. In 7 of 9 patients, 8 conduit obstruction events were assessed by Doppler interrogation of the native LVOT and by cardiac catheterization. Five patients underwent 6 MRI scans. RESULTS: In all cases of obstruction diagnosed by catheterization (56.3 +/- 21.9 mm Hg), Doppler echocardiography demonstrated gradients across the native LVOT (69.3 +/- 21.2 mm Hg, r = 0.67). Because 2D echocardiography could not visualize the entire conduit in any patient, 2- and 3-dimensional MRI was used successfully to evaluate anatomy and identify the site of obstruction. All patients manifested conduit obstruction. Four (44%) of 9 patients died, 3 underwent the Ross operation, 1 continues to live with his original conduit, and 1 was lost to follow-up. CONCLUSIONS: A gradient by Doppler interrogation of the native LVOT is an indirect means of assessing conduit obstruction. MRI is a useful tool to complement anatomic diagnosis by echocardiography. Conduit obstruction is common, and late mortality rates appear to be high.

Diastolic biomechanics in normal infants utilizing MRI tissue tagging.

BACKGROUND: Most of what is known about diastolic function in normal infants is derived from flow and pressure measurements. Little is known about regional diastolic strain and wall motion. METHODS AND RESULTS: Magnetic resonance tissue tagging was performed in 11 normal infants to determine regional diastolic strain and wall motion. Tracking diastolic motion of the intersection points and finite strain analysis yielded regional rotation, radial displacement, and E(1) and E(2) strains at 3 short-axis levels (significance was defined as P<0.05). E(2) "circumferential lengthening" strains were significantly greater at the lateral wall, regardless of short-axis level, whereas E(1) "radial thinning" strains were similar in all wall regions at all short-axis levels. In general, no differences were noted in strain dispersion within a wall region or in endocardial/epicardial strain at all short-axis levels. At all short-axis levels, septal radial motion was significantly less than in other wall regions. No significant differences in radial wall motion between short-axis levels were noted. Rotation was significantly greater at the apical short-axis level in all wall regions than in other short-axis levels, and it was clockwise. At the atrioventricular valve, septal and anterior walls rotated slightly clockwise, whereas the lateral and inferior walls rotated counterclockwise. CONCLUSIONS: Diastolic biomechanics in infants are not homogeneous. The lateral walls are affected most by strain, and the septal walls undergo the least radial wall motion. Apical walls undergo the most rotation. These normal data may help in the understanding of diastolic dysfunction in infants with congenital heart disease.

Congenital Heart Surgery Nomenclature and Database Project: systemic venous anomalies.

The extant nomenclature for systemic venous anomalies is reviewed for the purpose of establishing a unified reporting system. The subject was debated and reviewed by members of the STS-Congenital Heart Surgery Database Committee and representatives from the European Association for Cardiothoracic Surgery. All efforts were made to include all relevant nomenclature categories using synonyms where appropriate. This nomenclature system classifies systemic venous anomalies into two primary groups by venous segment: (1) systemic venous anomalies, superior vena cava; and (2) systemic venous anomalies, inferior vena cava. Subsets are clearly defined and categorized. A comprehensive database set is presented that is based on a hierarchical scheme. Data are entered at various levels of complexity and detail that can be determined by the clinician. These data can lay the foundation for comprehensive risk stratification analyses. A minimum database set is also presented that will allow for data sharing and would lend itself to basic interpretation of trends. Outcome tables relating diagnoses, procedures, and various risk factors are presented.

Surgical approach to complicated cervical aortic arch: anatomic, developmental, and surgical considerations.

BACKGROUND: Abnormalities of brachiocephalic arterial branching and arch laterality are common in patients with a cervical aortic arch. In addition, structural anomalies of the arch such as obstruction, aneurysms, and tortuosity are found in a significant number of cases. METHODS: Between 1990 and 1998, 6 patients underwent surgery for an obstructed right cervical arch. A significant obstruction was present at the transverse or distal arch in all patients, and was recurrent after previous repair in 2. In 1 patient, there was also a multi-lobed aneurysm of the aortic segment contiguous to the obstruction, and in 2 there was marked tortuosity of the arch. In all cases, the order of origin of the head and neck vessels was abnormal, and obstruction of 1 or more brachiocephalic vessels was found in 3. A vascular ring was present in all patients, with a right aortic arch and aberrant left subclavian artery in 4 patients and a double aortic arch with a dominant right cervical arch in 2. The descending aorta was circumflex (left-sided) in 3 patients. Three patients were repaired through a standard right posterolateral thoracotomy, and 3 through a median sternotomy. Patch augmentation aortoplasty was used in 2 patients, a tube graft from the ascending to descending aorta in 2, end to side anastomosis of the descending aorta to the proximal arch in 1, and direct anastomosis to reconstruct an atretic left-sided component of a double arch in 1. RESULTS: Repair was successful in all cases, with no perioperative complications. At follow-up ranging from 1 to 9 years, all patients were alive and well, with no recurrence of arch obstruction or other significant complications. Fluorescent in situ hybridization revealed microdeletion of chromosome 22q11 in 1 patient (not performed in the others). CONCLUSIONS: Structural anomalies of the arch are relatively common in patients with a cervical aortic arch. Such abnormalities may be the result of hemodynamic conditions and/or abnormal vascular tissue related either to the cervical position of the arch or its embryologic precursors. Given the highly variable anatomy of patients with a complicated cervical aortic arch, surgical considerations will vary in kind.

Membranous subpulmonic stenosis associated with ventricular septal defect and aortic insufficiency.

We present a case report of a patient with conal septal hypoplasia (supracristal) ventricular septal defect (VSD) complicated by aortic insufficiency (AI) and subpulmonic stenosis from a fibrous membrane. The development of AI with VSD is a well-recognized problem. However, the association of VSD, AI, and significant right ventricular outflow tract obstruction (RVOTO) is less common. Mechanisms of RVOTO include prolapse of an aortic valve cusp across the VSD, as well as infundibular hypertrophy or muscle bundles. Technical echocardiographic issues can make the diagnosis of VSD, AI, and RVOTO challenging. The presence of a discrete fibrous subpulmonary membrane is uncommon in this setting.

Regional wall motion and strain of transplanted hearts in pediatric patients using magnetic resonance tagging.

Abnormal ventricular systolic torsion is present during histological rejection in adult cardiac transplant patients. Because biomechanical properties of transplanted hearts in the baseline state have not been studied in children, pediatric patients were evaluated to quantify ventricular wall motion and strain. Eight transplant studies and eight normal controls were evaluated. Magnetic resonance tagging was performed to determine radial shortening, twist, and strain in four ventricular anatomic areas at two short-axis levels. Controls had counterclockwise twist. Six transplant studies had clockwise twist, six had akinetic regions, and all had regions of no twist. One demonstrated paradoxical motion of the septum. A comparison between transplant patients and controls revealed strain to be similar in all regions except one (superior wall at the atrioventricular valve level) and strain distribution to be different only in two of eight regions. Pediatric transplant patients demonstrate regional wall motion abnormalities in the absence of rejection. Compared with normal controls, the transplanted left ventricle maintains normal strain in the presence of abnormal twist. This may be a compensatory mechanism and have clinical implications.

Caval contribution to flow in the branch pulmonary arteries of Fontan patients with a novel application of magnetic resonance presaturation pulse.

BACKGROUND: A complete understanding of fluid mechanics in Fontan physiology includes knowledge of the caval contributions to right (RPA) and left (LPA) pulmonary arterial blood flow, total systemic venous return, and relative blood flow to each lung. METHODS AND RESULTS: Ten Fontan patients underwent cine MRI. Three cine scans of the pulmonary arteries were performed: (1) no presaturation pulse, (2) a presaturation pulse labeling inferior vena cava (IVC) blood (signal void), and (3) a presaturation pulse labeling superior vena cava (SVC) blood. The relative signal decrease is proportional to the amount of blood originating from the labeled vena cava. This method was validated in a phantom. Whereas 60+/-6% of SVC blood flowed into the RPA, 67+/-12% of IVC blood flowed toward the LPA. Of the blood in the LPA and RPA, 48+/-14% and 31+/-17%, respectively, came from the IVC. IVC blood contributed 40+/-16% to total systemic venous return. The distributions of blood to each lung were nearly equal (RPA/LPA blood=0.94+/-11). CONCLUSIONS: In Fontan patients with total cavopulmonary connection, SVC blood is directed toward the RPA and IVC blood is directed toward the LPA. Although the right lung volume is larger than the left, an equal amount of blood flow went to both lungs. LPA blood is composed of equal amounts of IVC and SVC blood because IVC contribution to total systemic venous return is smaller than that of the SVC. This technique and these findings can help to evaluate design changes of the systemic venous pathway to improve Fontan hemodynamics.

Growth characteristics of the aortic arch after the Norwood operation.

OBJECTIVES: We sought to characterize the growth of the reconstructed aortic arch after the Norwood operation (NO). BACKGROUND: The first stage of surgical palliation of hypoplastic left heart syndrome (HLHS), the NO, includes augmentation of the aortic arch with homograft. Growth characteristics of the reconstructed aortic arch, which is comprised of both native aortic tissue and homograft, have not been characterized. METHODS: Retrospectively, we examined the serial echocardiograms of 50 patients with HLHS who underwent NO to determine the diameter of the reconstructed transverse arch. Measurements were taken immediately after NO and at two other points (1 to 11 years of age). In addition, the autopsy specimens of 10 other patients with HLHS who underwent NO were examined to determine the contribution of native aortic tissue to the overall size of the reconstructed arch at the time of death (12 to 34 months). RESULTS: The diameter of the transverse aorta increased after NO in all subjects. Its rate of growth paralleled that seen in the normal population, though the reconstructed arch had a significantly larger diameter throughout childhood. Examination of autopsy specimens demonstrated a mean increase in circumference of the native aortic tissue of 0.67 cm (p value <0.01), whereas there was no significant change in homograft circumference. CONCLUSIONS: After reconstruction of the aortic arch in HLHS, the diameter of the arch continues to increase throughout childhood, and this increase is due to growth of the native aortic tissue.

Mechanics of the single left ventricle: a study in ventricular-ventricular interaction II.

BACKGROUND: Left ventricular (LV) effects on right ventricular (RV) function are well known. Less is understood about the effect of the RV on systemic LV mechanics. To determine this interaction, we compared systemic LVs with and without an RV mechanically coupled to them. METHODS AND RESULTS: MR myocardial tagging was used to examine 18 subjects with systemic LVs: 10 with functional single LVs (SLV) and 8 normal subjects (NL). Tracking the systolic motion of the intersecting stripes were used to determine regional twist and radial motion. Finite strain analysis was applied to derive principal strains at the atrioventricular valve (AVV) and apical short-axis levels and in 4 anatomic wall regions. Similar E1 (circumferential shortening) strain and heterogeneity of strain were noted between SLV and NL except in the septal wall. At the septal wall, NL displayed greater absolute strain (AVV=-0.16+/-0.02, apex=-0.17+/-0.02) and less heterogeneity of strain than SLV (AVV= -0.12+/-0.02, apex=-0.13+/-0.02). Similar E2 (wall thickening) strain and heterogeneity of strain were also noted between SLV and NL except again at the septal wall. At the septal wall, SLV displayed greater absolute E2 strain (AVV=0.17+/-0.08, apex=0.19+/-0.09) and less heterogeneity of strain than NL (AVV=0.07+/-0.07, apex=0.05+/-0.05). SLV twisted significantly less counterclockwise than NL in 6 of 8 wall regions and actually twisted clockwise at the AVV lateral wall. Although there was no significant difference between groups in radial wall motion, the septal and inferior walls of SLV demonstrated significantly less radial motion compared with other SLV walls. CONCLUSIONS: A major influence of the RV on systemic LV strain and radial motion occurs in the septal wall, whereas absence of the RV causes marked differences in LV twist. These findings may yield clues to the long-term functioning of the SLV and be useful in determining strategies for RV augmentation of LV function.

Surgical management of tricuspid atresia and anomalous left brachiocephalic vein.

An anomalous left brachiocephalic vein is an uncommon systemic venous anomaly, which usually has no clinical significance. We describe a case of tricuspid atresia with such an anomalous left brachiocephalic vein. The presence of this unusual venous anomaly had a number of implications in the surgical management of the tricuspid atresia.