Inga Voges

Normal values of aortic dimensions, distensibility, and pulse wave velocity in children and young adults: a cross-sectional study

BackgroundAortic enlargement and impaired bioelasticity are of interest in several cardiac and non-cardiac diseases as they can lead to cardiovascular complications. Cardiovascular magnetic resonance (CMR) is increasingly accepted as a noninvasive tool in cardiovascular evaluation. Assessment of aortic anatomy and bioelasticity, namely aortic distensibility and pulse wave velocity (PWV), by CMR is accurate and reproducible and could help to identify anatomical and bioelastic abnormalities of the aorta. However, normal CMR values for healthy children and young adults are lacking.MethodsSeventy-one heart-healthy subjects (age 16.4 ± 7.6 years, range 2.3 - 28.3 years) were examined using a 3.0 Tesla CMR scanner. Aortic cross-sectional areas and aortic distensibility were measured at four positions of the ascending and descending thoracic aorta. PWV was assessed from aortic blood flow velocity measurements in a aortic segment between the ascending aorta and the proximal descending aorta. The Lambda-Mu-Sigma (LMS) method was used to obtain percentile curves for aortic cross-sectional areas, aortic distensibility and PWV according to age.ResultsAortic areas, PWV and aortic distensibility (aortic cross-sectional areas: r = 0.8 to 0.9, p < 0.001; PWV: r = 0.25 to 0.32, p = 0.047 to 0.009; aortic distensibility r = -0.43 to -0.62, p < 0.001) correlated with height, weight, body surface area, and age. There were no significant sex differences.ConclusionsThis study provides percentile curves for cross-sectional areas, distensibility and pulse wave velocity of the thoracic aorta in children and young adolescents between their 3rd and 29th year of life. These data may serve as a reference for the detection of pathological changes of the aorta in cardiovascular disease.

Maladaptive Aortic Properties in Children After Palliation of Hypoplastic Left Heart Syndrome Assessed by Cardiovascular Magnetic Resonance Imaging

Background— The status of the reconstructed aorta in hypoplastic left heart syndrome is considered an important determinant of long-term prognosis. Therefore, we assessed the anatomy, elastic properties, and viability of the aorta and right ventricular function in patients with hypoplastic left heart syndrome by cardiovascular magnetic resonance imaging. Methods and Results— Cardiovascular magnetic resonance imaging was performed in 40 patients with hypoplastic left heart syndrome (age, 6.0±2.2 years) and 13 control subjects (age, 6.6±2.2 years). Aortic dimensions and distensibility were calculated at different locations of the aorta using gradient-echo cine imaging at 3.0 T. Additionally, pulse-wave velocity, right ventricular ejection fraction, and aortic late gadolinium enhancement for viability assessment were measured. Compared with control subjects, patients with hypoplastic left heart syndrome had increased axial diameters of the aortic root (36.0±5.5 versus 24.1±2.7 mm/m2; P<0.01), ascending aorta (32.0±5.0 versus 21.3±1.5 mm/m2; P<0.01), and transverse aortic arch (22.7±5.2 versus 18.7±2.5 mm/m2; P<0.01). Wall distensibility was reduced in the ascending aorta (4.1±2.4 versus 13.5±7.2 10−3 mm Hg−1; P<0.01) and transverse aortic arch (5.4±3.6 versus 10.3±3.5 10−3 mm Hg−1; P<0.01). Pulse-wave velocity trended higher in patients (P=0.06). Reduced distensibility in the ascending aorta correlated with the amount of late gadolinium enhancement in a volume that included the aortic root and the ascending aorta (r=−0.72, P<0.01), and both parameters correlated with decreased right ventricular ejection fraction. Conclusions— Adverse aortic properties post palliation of hypoplastic left heart syndrome manifest themselves by aortic dilatation, decreased distensibility, and increased volume of nonviable aortic wall tissue. The negative association between aortic late gadolinium enhancement and right ventricular ejection fraction suggests unfavorable aortic-ventricular coupling. The potential impact of these findings on long-term right ventricular function should be evaluated in future studies.

Adverse results of a decellularized tissue-engineered pulmonary valve in humans assessed with magnetic resonance imaging.

OBJECTIVES Matrix P® and Matrix P plus® tissue-engineered pulmonary valves (TEPV) were offered as an improvement for pulmonary valve replacement (PVR) because of recellularization by host cells. The high frequency of graft failure gave reason to evaluate the underlying morphological substrate using magnetic resonance imaging (MRI) and histology. METHODS Between June 2006 and August 2008, 17 Matrix P® and 10 Matrix P plus® TEPVs were implanted in 26 patients with a median age of 12.4 (range: 0.8-38.7, interquartile range: 6.1-18.1) years. The grafts were studied by MRI, and underwent histological examination when explantation was required. RESULTS Surgical (n = 13) or transcatheter (n = 1) TEPV replacement because of graft failure was needed in 14 cases (52%) 19 (0.5-53) months after implantation. MRI detected significant TEPV stenosis with mild insufficiency (V(max) = 3.7 ± (standard deviation) 0.5 m/s, regurgitant fraction (RGF) = 10 ± 3%) and stenosis with moderate-to-severe insufficiency (V(max) = 3.5 ± 0.8 m/s, RGF = 38 ± 10%) in 6 patients, respectively, and severe insufficiency (RGF = 40%) in 1 patient. In patients with graft failure, MRI showed hyperenhancement and TEPV wall thickening. Histology revealed severe inflammation, increased fibrous tissue and foreign-body reaction against valve leaflets and fascial tissue, while TEPV endothelialization was not detected in any case. CONCLUSIONS The high frequency of Matrix P® and Matrix P plus® graft failure can be related to inflammation and fibrosis revealed by MRI and histology. Our results do not support the use of these valves for PVR and suggest careful follow-up examinations, including MRI for early detection of graft inflammation and fibrosis.

Use of surveillance criteria reduces interstage mortality after the Norwood operation for hypoplastic left heart syndrome

OBJECTIVES While hospital mortality after the Norwood operation for hypoplastic left heart syndrome (HLHS) has decreased steadily, interstage mortality until the superior cavopulmonary anastomosis (SCPA) remains a major concern. Our aim was to institute a home surveillance programme to decrease interstage mortality. METHODS We enrolled 45 HLHS patients surviving the Norwood operation into our home surveillance programme and compared them with 97 patients treated before the initiation of the programme and with a third group of 20 patients not discharged between the first- and the second-stage operation. While still in hospital, parents were taught to record weight and fluid intake as well as oxygen saturations with the help of a vital sign monitor. During the last week of the hospital stay, the following criteria had to be met: oxygen saturation >75%, weight gain of at least 20-30 g in 3 days and a maximum weight loss of 30 g in a day. After discharge, these criteria had to be maintained at all times or the parents were supposed to call our hospital. Additionally, an experienced paediatric cardiologist from our centre called the parents at home once a week. RESULTS Interstage mortality was reduced significantly from 12.4% (12/97) to 2.2% (1/45) (P = 0.042). The number of patients, who were not discharged before the SCPA, was significantly higher after the start of the home surveillance programme (12/57 vs. 8/105, P = 0.022). After discharge, 14 (31%) infants breached the surveillance criteria. Of these, one patient died and eight patients were operated earlier (SCPA, n = 6; shunt replacement, n = 2). The remaining five patients could be discharged home after observation. Children in the home surveillance programme were younger [102 (67-299) vs. 152 (77-1372) days, P = 0.001] and weighed less (5.09 ± 0.79 vs. 5.75 ± 1.22 kg, P = 0.001) at the SCPA compared with the remainder. Early survival after SCPA was not different. CONCLUSIONS The home surveillance programme led to an important decrease in interstage mortality. The adherence to the surveillance criteria before discharge resulted in a larger number of patients receiving inpatient treatment until SCPA. Earlier SCPA in the surveillance group had no negative impact on early survival after SCPA.

Implications of early aortic stiffening in patients with transposition of the great arteries after arterial switch operation.

Background— The elastic function of the aorta in patients with transposition of the great arteries after arterial switch operation (ASO) is suspected to be important for long-term prognosis. Methods and Results— Fifty-one patients and 34 controls were studied at 3.0 Tesla with MRI. Forty-three patients (12.8±6.9 years) underwent 1-stage ASO, 8 patients (23.8±6.9 years) had prior pulmonary artery banding (2-stage ASO). Aortic dimensions, distensibility, pulse wave velocity, aortic arch angle, left ventricular (LV) mass, LV systolic function and left atrial (LA) volumes, and LA passive emptying function as marker of LV diastolic function were assessed. Compared with controls, patients had increased aortic root areas (602.6±240.5 versus 356.8±113.4 mm2/m; P<0.01) and reduced distensibility of the thoracic aorta most pronounced at the aortic root (3.2±2.0 versus 9.1±4.7×10−3 mm Hg−1; P<0.01). Aortic distensibility correlated negatively with the aortic areas (P<0.01). Pulse wave velocity was higher in adults after ASO (5.0±1.0 versus 3.8±1.3 m/s; P<0.01). In contrast to controls pulse wave velocity and distensibility correlated with age in patients (P=0.04 to <0.01), LV mass was higher in patients (P=0.02). LA volumes correlated negatively with aortic root and ascending aortic distensibility and positively with pulse wave velocity (P<0.05). In patients, LA passive emptying function was lower (27.3±8.9 versus 41.1±6.0; P<0.01) and correlated with aortic root distensibility (P=0.004). Conclusions— Reduced aortic bioelasticity and aortic root dilatation are present in transposition of the great artery patients post ASO and are likely to contribute to LV diastolic dysfunction. Impaired aortic bioelasticity was strongly associated with age, suggesting the usefulness of follow-up studies for early onset of degenerative cardiovascular disease.

Restrictive enlargement of the pulmonary annulus at surgical repair of tetralogy of Fallot: 10-year experience with a uniform surgical strategy

OBJECTIVES Retrospective data suggest that a wide pulmonary annulus after Fallot repair aggravates pulmonary regurgitation. Therefore, since 1997, in our institution transannular patch enlargement was only intended for patients with a native pulmonary annulus z-score less than -4. If transannular patching was needed, enlargement was aimed to diameters within the range of a z-score of -2. We sought to determine whether this strategy of restrictive enlargement of the pulmonary annulus was adequate to reduce transannular patch rate and to limit pulmonary annulus width without increased right ventricular pressure load. METHODS Two-hundred-and-sixteen Fallot patients were retrospectively analysed. Ninety-eight patients underwent repair between 1997 and 2006 adhering to our uniform strategy (Group 1). One hundred and eighteen patients were operated between 1977 and 1996 without a uniform strategy (Group 2). Transannular patch rate, native and postoperative pulmonary annulus z-score, postoperative right ventricular outflow tract velocity on echocardiography and early reoperation rate for right ventricular outflow tract obstruction were analysed in both groups. RESULTS Compared to Group 2, patients in Group 1 were younger at repair, transannular patch rate was significantly reduced (32 vs 68%, p<0.0001) and postoperative pulmonary annulus diameters were smaller (z-score -2.1+/-1.5 vs 0.0+/-3.1, p<0.0001). However, no difference in right ventricular outflow tract velocity (2.4+/-0.8 vs 2.2+/-0.8m/s; p=NS) or the incidence of early reoperation for right ventricular outflow tract obstruction was found between the groups (3/98 vs 1/118; p=NS). CONCLUSION Restrictive enlargement of the pulmonary annulus at Fallot repair lowers transannular patch rate, limits the postoperative width of the pulmonary annulus but does not result in increased right ventricular pressure load or reoperation rate for residual right ventricular outflow tract obstruction. A limitation of postoperative pulmonary regurgitation can be expected when the extent of pulmonary annulus enlargement at repair is limited.

Comparison of right ventricular deformation and dyssynchrony in patients with different subtypes of hypoplastic left heart syndrome after Fontan surgery using two-dimensional speckle tracking

BACKGROUND The left ventricle in patients with hypoplastic left heart syndrome may influence right ventricular function and outcome. We aimed to investigate differences in right ventricular deformation and intraventricular dyssynchrony between hypoplastic left heart syndrome patients with different anatomical subtypes and left ventricle sizes after Fontan surgery using two-dimensional speckle tracking. PATIENTS AND METHODS We examined 29 hypoplastic left heart syndrome patients aged 5.4 plus or minus 2.8 years after Fontan surgery and compared 15 patients with mitral and aortic atresia with the remaining 14 patients with other anatomic subtypes. We used two-dimensional speckle tracking to measure the global and regional systolic longitudinal strain and strain rate as well as intraventricular dyssynchrony. RESULTS Global strain (-19.5, 2.8% versus -17.4, 3.9%) and global strain rate (-1.0, 0.2 per second versus -0.9, 0.3 per second) were not different between groups. The mitral and aortic atresia group had higher strain in the basal septal (-13.0, 5.0% versus -3.9, 9.3%, p = 0.003) and mid-septal (-19.4, 4.7% versus -13.2, 6.5%, p = 0.009) segments, and higher strain rates in the mid-septal segment (-1.14, 0.3 per second versus -0.95, 0.4 per second, p = 0.047), smaller left ventricle area (0.18, 0.41 square centimetre versus 2.83, 2.07 square centimetre, p = 0.0001), and shorter wall-to-wall delay (38, 29 milliseconds versus 81, 57 milliseconds, p = 0.02). CONCLUSION Significant differences in regional deformation and intraventricular dyssynchrony exist between the mitral and aortic atresia subtype with small left ventricles and the other anatomic subtypes with larger left ventricles after Fontan surgery.

Arterial elastance and its impact on intrinsic right ventricular function in palliated hypoplastic left heart syndrome

BACKGROUND Systemic right ventricular (RV) function is a major determinant of long-term outcome in patients with palliated hypoplastic left heart syndrome (HLHS). Abnormal elastic properties of the reconstructed aorta may negatively impact on ventricular function. We therefore aimed to assess arterial elastance and its relationship to systemic RV function in these patients. METHODS Fifty-six HLHS patients (median age 5.4 years; range 2.9-14.2 years) were studied at a median of 2.6 years (range 0.8-12.7 years) after completion of the Fontan circulation with the pressure-volume conductance system. RESULTS Arterial elastance (Ea) was abnormally high and correlated inversely with RV ejection fraction (r=-0.42, P=0.001). However, end systolic elastance (Ees) - a load independent measure of intrinsic systolic ventricular function - and more so end diastolic stiffness (Eed) were positively correlated with Ea (Ees vs. Ea: r=0.44, P=0.001: Eed vs. Ea: r=0.62, P<0.0001). Patients who were treated for significant aortic arch obstruction after surgical palliation showed higher Ea and Eed even four years after successful treatment compared to the remainder of the group (Ea: 3.4 ± 1.2 vs. 2.8 ± 1.0 mmHg/ml, P=0.04 and Eed: 0.67 ± 0.44 vs. 0.45 ± 0.3 mmHg/ml, P=0.04). CONCLUSIONS Arterial elastance is abnormally high in palliated HLHS patients and negatively impacts on ejection fraction but not on intrinsic systolic RV function early after completion of the Fontan circulation. Increased arterial elastance, however, is associated with increased RV diastolic stiffness with potential adverse effects on long-term outcome. Furthermore, arterial elastance and diastolic stiffness are particularly high in patients who needed treatment for aortic arch obstruction.

Fifteen-year single-center experience with the Norwood operation for complex lesions with single-ventricle physiology compared with hypoplastic left heart syndrome

OBJECTIVE The Norwood procedure, the first surgical step of staged palliation for hypoplastic left heart syndrome, is also applied for other complex single-ventricle lesions with systemic outflow tract obstruction or aortic arch hypoplasia. We reviewed our 15-year institutional experience with the Norwood procedure for patients with and without hypoplastic left heart syndrome. METHODS A total of 41 patients without hypoplastic left heart syndrome and 212 patients with hypoplastic left heart syndrome who underwent a Norwood procedure between January 1996 and December 2010 were enrolled. Full medical records were reviewed to assess the determinants of outcome. RESULTS Early failure (death or cardiac transplantation) was 7% in patients without hypoplastic left heart syndrome and 13% in patients with hypoplastic left heart syndrome (P = .29). Frequency of postoperative complications, duration of postoperative ventilation, and length of vasoactive drug treatment were not different between groups. Transplant-free survival until the second operative step trended to be higher for patients without hypoplastic left heart syndrome (92% vs 80%, P = .067). Recurrent aortic arch obstruction was more common in patients without hypoplastic left heart syndrome (15/39 vs 32/171, P = .008), but there were 4 patients with stenosis of the proximal aortic arch. In subsequent procedures, 31 patients without hypoplastic left heart syndrome underwent superior cavopulmonary anastomosis and 5 biventricular repair. Overall transplant-free survival was not different between groups (P = .119) but trended to be higher in patients with a systemic or substantial left ventricle remnant contributing to cardiac output (P = .082). CONCLUSIONS Early and long-term survivals and postoperative complications were similar between patients with and without hypoplastic left heart syndrome undergoing a Norwood operation. Recurrent aortic arch obstruction was common in both groups but more prevalent in patients without hypoplastic left heart syndrome.

New insights in the Fontan circulation: 4-dimensional respiratory- and ECG-triggered phase contrast magnetic resonance imaging

Background Evaluation of blood flow characteristics in total cavo-pulmonary connection (TCPC) with CMR remains difficult due to its strong modulation by respiration, and is not yet entirely understood. New approaches using 4D phase contrast magnetic resonance imaging (4D PC MRI) are promising and can contribute to the understanding of hemodynamics in the Fontan Circulation. Our objective was to compare flow, velocities, wall shear stress (WSS) and circulation in the TCPC using respiratory- and ECG triggered 4D PC MRI. Methods 10 children with hypoplastic left heart syndrome were evaluated after surgical completion of the Fontan circulation (TCPC with lateral intra-atrial tunnel) in a single center. In all patients one respiratory- (80 -100 phases) and one ECG-triggered (30 phases) 4D PC MRI covering the whole thorax, voxel size ranging from isotropic 1.5 to 2.0 mm were acquired during a single CMR examination with a custom-made electronic respiratory triggering compatible with our scanner. Dedicated commercial and custom software was used for further analysis of flow, velocity, WSS and circulation. Results