Effects of pulmonary regurgitation on distensibility and flow of the branch pulmonary arteries in tetralogy of Fallot.

Significant pulmonary regurgitation (PR) after repair of tetralogy of Fallot (TOF) may affect flow in the pulmonary artery (PA) side branches. We sought to assess flow changes and distensibility of the PA side branches in vivo and test correlation with the degree of PR and right-ventricular (RV) dilatation. Thirty patients after TOF repair and 16 controls underwent cardiovascular magnetic resonance for quantification of RV volumes and measurement of flow in the PA side branches. RV volumes and function, blood flow volumes, and cross-sectional area of the main, left (LPA), and right (RPA) PA were measured and regurgitant volumes and distensibility calculated. Results were compared between the LPA and the RPA and between patients and controls. Median regurgitation fraction of PR was 41 % (range 22-60 %). Regurgitant fraction was greater in the LPA (40 %) than in the RPA (29 %), resulting in lower net flow into the LPA (p < 0.001). LPA area was significantly greater than that of the RPA (303.9 vs. 232.7 mm(2)/m(2)) (p < 0.0001). The LPA showed lower distensibility than the RPA (39 vs. 44 %). PA side branch distensibility correlated with MPA regurgitant volume (p = 0.001), MPA regurgitant fraction (p = 0.001), and RV end-diastolic volume (p = 0.03). PA side branches have greater distensibility in patients with PR than in normal subjects. Significant PR leads to changes in flow profile and distensibility of the PA side branches. The LPA shows greater regurgitant volume and greater area but lower distensibility than the RPA.

Characterization of cardiac tumors in children by cardiovascular magnetic resonance imaging: a multicenter experience.

OBJECTIVES: The aim of this study was to report the results of an international multicenter experience of cardiac magnetic resonance imaging (MRI) evaluation of cardiac tumors in children, each with histology correlation or a diagnosis of tuberous sclerosis, and to determine which characteristics are predictive of tumor type. BACKGROUND: Individual centers have relatively little experience with diagnostic imaging of cardiac tumors in children, because of their low prevalence. The accuracy of cardiac MRI diagnosis on the basis of a pre-defined set of criteria has not been tested. METHODS: An international group of pediatric cardiac imaging centers was solicited for case contribution. Inclusion criteria comprised: 1) age at diagnosis ≤18 years; 2) cardiac MRI evaluation of cardiac tumor; and 3) histologic diagnosis or diagnosis of tuberous sclerosis. Data from the cardiac MRI images were analyzed for mass characteristics. On the basis of pre-defined cardiac MRI criteria derived from published data, 3 blinded investigators determined tumor type, and their consensus diagnoses were compared with histologic diagnoses. RESULTS: Cases (n = 78) submitted from 15 centers in 4 countries had the following diagnoses: fibroma (n = 30), rhabdomyoma (n = 14), malignant tumor (n = 12), hemangioma (n = 9), thrombus (n = 4), myxoma (n = 3), teratoma (n = 2), and paraganglioma, pericardial cyst, Purkinje cell tumor, and papillary fibroelastoma (n = 1, each). Reviewers who were blinded to the histologic diagnoses correctly diagnosed 97% of the cases but included a differential diagnosis in 42%. Better image quality grade and more complete examination were associated with higher diagnostic accuracy. CONCLUSIONS: Cardiac MRI can predict the likely tumor type in the majority of children with a cardiac mass. A comprehensive imaging protocol is essential for accurate diagnosis. However, histologic diagnosis remains the gold standard, and in some cases malignancy cannot be definitively excluded on the basis of cardiac MRI images alone.

Geometry and dimensions of the pulmonary artery bifurcation in children and adolescents: assessment in vivo by contrast-enhanced MR-angiography.

We sought to establish normal values for the diameters of the main (MPA), right (RPA), and left (LPA) pulmonary arteries and for the angles describing the geometry of the pulmonary artery bifurcation in children by using contrast-enhanced magnetic resonance angiography (CE-MRA). CE-MRA was performed in 69 children without cardiovascular disease. The median age was 10 ± 4.9 years (range 2-20), weight 37.4 ± 18.5 kg (10-82), body surface area (BSA) 1.18 ± 0.4 m(2) (0.48-2.07). The pulmonary artery diameters and angles were measured at standardized sites and projections. Regression analysis of diameters and angles in relation to BSA demonstrated linear relationship between the cross-sectional diameters of the pulmonary arteries and the square root of BSA (BSA(0.5)). Normalized mean diameters were for the MPA 17.6 ± 5.1 mm/m(2), origin of RPA 13.1 ± 2.9 mm/m(2), origin of LPA 14.2 ± 2.9 mm/m(2). The MPA showed a mean antero-posterior inclination of 33° ± 8° and a lateral leftward angulation of 18° ± 5°. The mean angle of the bifurcation was 99.5° ± 10.3°. Both side branches showed a supero-inferior course of the proximal segments, steeper for the RPA (7.7° ± 6.5°) than for the LPA (2.1° ± 7.8°). Normative curves in relation to BSA are presented for all measurements. This study provides normative values by CE-MRA for the main pulmonary artery and its side branches in children during somatic growth. These data can be used for identifying pulmonary arteries anomalies in children, and evaluate the need and the modality for treatment.

Feasibility of perfusion cardiovascular magnetic resonance in paediatric patients.

AIMS: As coronary artery disease may also occur during childhood in some specific conditions, we sought to assess the feasibility and accuracy of perfusion cardiovascular magnetic resonance (CMR) in paediatric patients. METHODS AND RESULTS: First-pass perfusion CMR studies were performed under pharmacological stress with adenosine and by using a hybrid echo-planar pulse sequence with slice-selective saturation recovery preparation. Fifty-six perfusion CMR examinations were performed in 47 patients. The median age was 12 years (1 month-18 years), and weight 42.8 kg (2.6-82 kg). General anaesthesia was required in 18 patients. Mean examination time was 67 +/- 19 min. Diagnostic image quality was obtained in 54/56 examinations. In 23 cases the acquisition parameters were adapted to patient's size. Perfusion CMR was abnormal in 16 examinations. The perfusion defects affected the territory of the left anterior descending coronary artery in 11, of the right coronary artery in 3, and of the circumflex coronary artery in 2 cases. Compared to coronary angiography, perfusion CMR showed a sensitivity of 87% (CI 52-97%) and a specificity of 95% (CI 79-99%). CONCLUSION: In children, perfusion CMR is feasible and accurate. In very young children (less than 1 year old), diagnostic image quality may be limited.

Muscle-sparing extrapleural approach for the repair of aortic coarctation.

BACKGROUND: This paper describes a muscle-sparing, extrapleural approach to repair aortic coarctation, and evaluates the results with established standards. METHODS: Forty consecutive patients with aortic coarctation (median age, 8 days; weight, 3.3 kg) were approached with a less invasive technique consisting of a short posterior thoracotomy, with only minimal (24 patients) or no (16 patients) division of thoracic wall muscles and a subperiosteal-extrapleural approach. Extended resection of the coarctation with enlargement of the distal aortic arch was performed in all patients. The median cross-clamp and operative times were 22 and 90 minutes, respectively. RESULTS: The repair was possible in all patients without needing conversion. There was no intraoperative or postoperative related complication. Two patients died early of low cardiac output as a result of ventricular fibroelastosis and respiratory failure. One patient died late of unrelated cause. The perioperative mean gradients across the neoarch were less than 5 mm Hg in all but 3 patients with proximal (2 patients) or mid arch (1) stenosis. The median ventilation time, intensive care unit stay, and hospital stay in isolated coarctation repairs was 2, 4.5, and 11 days, respectively. One patient had a recurrent stenosis at the site of surgical repair. Two patients underwent successful balloon dilatation, and 2 had surgical enlargement plasty of the proximal aortic arch at the time of intracardiac repair. None of the patients required chronic antihypertensive medication. At 29 months, freedom from reintervention on the isthmus and arch plus isthmus was 97.1% and 89.7%, respectively. CONCLUSIONS: A muscle-sparing, extrapleural approach for the repair of aortic coarctation is possible and provides results similar to conventional techniques. The approach reduces postoperative morbidity related to division of thoracic wall muscles and handling of the lung, restores a normal intercostal space, and produces superior cosmetic results, while at the same time leading to early and permanent relief of proximal hypertension.

Remodelling of the right ventricle after early pulmonary valve replacement in children with repaired tetralogy of Fallot: assessment by cardiovascular magnetic resonance.

AIMS: Correct timing of pulmonary valve replacement (PVR) is crucial for preventing complications of pulmonary regurgitation and right ventricular (RV) dilatation after repair of tetralogy of Fallot. We sought to assess the remodelling of the RV after early PVR in children, using cardiovascular magnetic resonance (CMR). METHODS AND RESULTS: Twenty children with severe pulmonary regurgitation and RV dilatation and mean age 13.9 +/- 3 years underwent CMR evaluation 5.6 +/- 1.8 months before and 5.9 +/- 0.6 months after PVR. PVR was performed when the RV end-diastolic volume exceeded 150 mL/m(2), as measured by CMR. The time interval between primary repair and PVR was 12 +/- 3 years. Post-operative CMR demonstrated a significant reduction of the RV end-diastolic volume from 189.8 +/- 33.4 to 108.7 +/- 25.8 mL/m(2) (P < 0.0001), of the RV end-systolic volume from 102.4 +/- 27.3 to 58.2 +/- 16.3 mL/m(2) (P < 0.0001), and of the RV mass from 48.7 +/- 12.3 to 35.8 +/- 7.7 g/m(2) (P < 0.0001). The RV ejection fraction did not change significantly. CONCLUSION: Prompt RV remodelling, with reduction of RV volume and mass, is observed after performing PVR if the RV end-diastolic volume exceeds 150 mL/m(2). Early PVR may prevent the detrimental complications of severe pulmonary regurgitation.

Early insertion of a pulmonary valve for chronic regurgitation helps restoration of ventricular dimensions.

BACKGROUND: This study assesses the results of early insertion of a pulmonary valve for chronic pulmonary regurgitation based on right ventricular volume measurements. METHODS: Valved conduits were prospectively inserted in 39 patients (aged 14 to 39 years) when the right ventricular (RV) end-diastolic volume index on magnetic resonance imaging (MRI) exceeded 150 mL/m2. Changes in morphology and function of the RV were prospectively analyzed by an MRI at 6 months postoperatively (available in 21 patients). RESULTS: There were no early or late deaths. All conduits showed good function at a median 15 month follow-up. Postoperative RV end-systolic and end-diastolic volumes showed a significant positive correlation (p = 0.005 and p < 0.0001), while postoperative left ventricular (LV) ejection fraction showed a significant negative correlation (p = 0.03) with preoperative RV end-diastolic volume index. Seven patients who achieved normal RV end-diastolic volume index (< or = 100 mL/m2) (group 1) when compared with 14 remaining patients (group 2) showed that they differed significantly with respect to their preoperative RV end-diastolic volume index (170.3 +/- 21.1 vs 203.6 +/- 35.6; p = 0.02) and postoperative LV ejection fraction (59.9 +/- 4.2 vs 54 +/- 7%, p = 0.03). CONCLUSIONS: Our results show that the improvement in ventricular dimensions and functions directly correlates with the timing of pulmonary valve insertion. Early insertion leads to normalization and late insertion leads only to improvement. These observations, along with a low morbidity for these reoperations, justify earlier reintervention in cases of chronic pulmonary regurgitation. A RV end-diastolic volume index of 150 mL/m2 seems to be a practical cutoff value to prescribe pulmonary valve insertion.