Uniqueness and bubbling of the 2-dimensional Landau-Lifshitz flow

Abstract.: We consider the Landau-Lifshitz flow on a bounded planar domain. An $\epsilon$ -regularity type a-priori estimate provides the analytic tool for the subsequent geometric description of the flow at isolated singularities. At forward isolated singularities where the energy is not left continuous the flow concentrates energy and develops bubbles. As in J.Qing's bubbling-energy-equality for the harmonic map flow, the energy loss at such a singularity can be recovered as a finite sum of energies of tangent bubbles. We then clarify a known uniqueness result for the Landau-Lifshitz flow and show how non-uniqueness of extensions of the flow after point singularities is related to backward bubbling. Finally the $\epsilon$ -regularity estimate also yields a partial compactness result for sequences of smooth solutions to the Landau-Lifshitz flow with uniformly bounded energy, defined on a planar domai

Effectiveness of Angiotensin-Converting Enzyme Inhibitors in Pediatric Patients with Mid to Severe Aortic Valve Regurgitation

The long-term benefit of angiotensin-converting enzyme inhibitors in pediatric patients with aortic valve regurgitation is under consideration. Eighteen patients with mid to severe aortic valve regurgitation were retrospectively evaluated. Echocardiographic parameters (left ventricular end-diastolic diameter, shortening fraction, left ventricular posterior wall thickness, and grade of aortic valve regurgitation) were analyzed before and during therapy with angiotensin-converting enzyme inhibitors. Data are given as standard deviation scores (Z-scores) derived from body surface-adjusted normal values. Median (interquartile range) age at start of therapy was 8.4 (5.4 to 10.0) years, and total follow-up 2.3 (0.9 to 5.4) years. Left ventricular end-diastolic diameter increased from 3.6 (2.3 to 4.5) to 3.7 (2.4 to 4.8), and left ventricular posterior wall diameter decreased from 1.9 (1.1 to 3.0) to 1.1 (0.5 to 2.3). Grade of aortic valve regurgitation increased from 3.5 (2.3 to 4.0) to 4.0 (2.0 to 4.0), and shortening fraction decreased from 39% (34% to 43%) to 37% (34% to 42%). No significant effect of angiotensin-converting enzyme inhibitors on left ventricular dimensions or function was found in our population of patients with mid to severe aortic valve regurgitation. Angiotensin-converting enzyme inhibitors may not alter left ventricular overload in pediatric patients with aortic valve regurgitatio

Balloon valvuloplasty of aortic valve stenosis in childhood: early and medium term results

Background: Isolated aortic valve stenosis in childhood is treated by balloon valvuloplasty. The role of independent risk factors for the outcome remains unclear. Material and methods: We analysed the early and medium term outcome of balloon valvuloplasty in isolated aortic valve stenosis in 44 pediatric patients with isolated, severe aortic valve stenosis at an age younger than 18 years, who received a primary balloon valvuloplasty during the last 5 years in our institution. We evaluated the type of aortic valve morphology, age, clinical status, and myocardial function at the time of the intervention as independent risk factor. Results: A significant early relief of the pressure gradient across the aortic valve (P < 0.001) after balloon valvuloplasty was found. This was independent of the aortic valve morphology. Two neonates with a highly stenotic tricuspid aortic valve and severely compromised haemodynamics died within the first 30 days after the intervention. During medium term follow up (mean 22.5 months) we observed a functional deterioration for the stenosis as well as for the insufficiency of the aortic valve. "Symptoms before intervention” is an independent risk factors (P < 0.001) for valvuloplasty failure. Patients at an "age at intervention ≤ 28 days” (P = 0.02) and patients with "reduced myocardial systolic function” (P = 0.01) had a shorter time to reintervention. Conclusions: The type of aortic valve morphology only has a weak predictive value for the outcome of balloon valvuloplasty during medium term follow up. Critical ill neonates with an impaired myocardial function are at a higher risk for valvuloplasty failur

Evolution of paced QRS and QTc intervals in children with epicardial pacing leads

Aims : Permanent ventricular pacing in children is associated with ventricular dysfunction due to asynchronous activation. It is unclear whether paced QRS intervals increase disproportionately over time, which could potentially cause ventricular dysfunction. Methods : A total of 52 children, with bipolar steroideluting epicardial leads implanted at a median age of 5.6 years (0.0-17.4), was analyzed and followed up to 12.2 years (median 3.7). Patients were subdivided in two groups: right (RV, n = 21) and left (LV, n = 31) ventricular pacing. To correct for age, standard deviation scores (Z-scores) for paced QRS and QTc intervals were calculated from published standard-ECG norm-values. As a measure for individual paced QRS and QTc interval changes, a regression slope coefficient (inclinei) was calculated for each patient's course. Results : Mean Z-scores for paced QRS intervals at first and last follow-up were 4.7 ± 1.2 and 4.9 ± 0.9 for group RV, 4.4 ± 1.1 and 4.8 ± 1.1 for group LV. Inclinei of paced QRS (group RV: 0.038 [-0.27-0.12], group LV: 0.147 [-0.05-0.30]; p = 0.07) and QTc intervals (group RV: 0.026 [-0.08-0.06], group LV: 0.023 [-0.04-0.09]; p = 0.63) did not differ between both groups and indicated limited interval changes over time. Conclusion : Neither epicardial pacing of the right nor left ventricle caused disproportionate paced QRS or QTc interval increases over time. An age-related prolongation of the electrical activation unlikely causes ventricular dysfunctio

Stent implantation and balloon angioplasty for treatment of branch pulmonary artery stenosis in children

Objectives: Comparison of the results of branch pulmonary artery stenosis treated with balloon angioplasty (BA) or stent implantation (SI) in children. Background: Branch pulmonary artery stenosis may be treated with BA or SI. Methods: We compared the results of 147 interventions of branch pulmonary artery stenosis in 87 children (median age 3.6 years). Patients were treated during 1989-2000 with BA and during 2001-2004 with SI. Primary endpoints were acute complications and reintervention during follow up. Secondary variables were age, vessel diameter increase, acute success rate, balloon/vessel diameter ratio, pulmonary artery hypoplasia indices, and procedure related factors. Results: The acute vessel diameter increase with BA (4.31 ± 1.98 vs. 7.15 ± 2.31 mm) and SI (3.71 ± 1.58 vs. 6.97 ± 2.68 mm) was significant within both groups (P < 0.001), but not between both groups. The reintervention rate was comparable between both groups, but median time to reintervention was shorter after SI in infants compared to BA. The balloon/vessel diameter ratio was on average higher in BA than the stent/vessel diameter ratio in SI (3.49 ± 2.16 vs. 2.42 ± 0.56; P < 0.05) and was a significant risk factor (P < 0.01) for the higher complication rate after BA (BA: 14.1% vs. SI: 4.8%). No mortality occurred in both groups. Conclusion: BA and SI are safe interventional catheter therapies of branch pulmonary artery stenosis. The immediate results of BA and SI are comparable. The higher complication rate after BA, especially in infants, was associated with a higher balloon/vessel diameter ratio. SI seems to be a safe permanent alternative with foreign material, but requires more reinterventions in infants due to its therapeutic strateg

Long-term follow-up of acute changes in coronary artery diameter caused by Kawasaki disease: risk factors for development of stenotic lesions

Objective: To investigate the long-term outcome of initially dilated/aneurysmatic coronary arteries in Kawasaki disease (KD) and to define risk factors for significant myocardial ischemia during follow-up, we retrospectively followed all pediatric patients with proven acute coronary changes due to KD in our institution. Methods and results: Since 1981, 38 children have been identified with coronary changes due to KD. The median age was 1.2years (0.1-12.8). In 37 patients therapy with intravenous immunoglobulin was initiated within 9days (1-30) after the beginning of KD. All received aspirin and three additionally received steroids. Median follow-up was 8.5years (0.5-24.8). We defined two groups: A aneurysm/ectasia of the coronary artery ≤5.0mm (n=23) and B aneurysm size >5.0mm (n=15). During follow-up, all coronary aneurysms of group A regressed to normal size, whereas in 14 patients of group B (93%) the aneurysms persisted or even increased in size. Four patients of group B developed severe coronary stenosis at the proximal and/or distal end of the aneurysm and needed an intervention (endovascular balloon dilation and stent implantation (n=2) or bypass surgery (n=2)) after a median time interval of 9.8years (1.0-15.6) after KD. They all had ECG changes preceding the intervention about 1year in advance. Maximum aneurysm size >5mm was a statistical significant predictive risk factor for myocardial ischemia. Conclusions: After KD, patients with a coronary aneurysm size >5.0mm need close follow-up assessments because of an elevated risk for the development of coronary stenotic lesions. In case of new and even unspecific ECG changes, coronary imaging modalities (angiography, MRI) have to be considered. Therapy options vary from percutaneous catheter interventions to bypass surgery and have to be selected individually for each patien

Assessment of Myocardial Function in Pediatric Patients with Operated Tetralogy of Fallot: Preliminary Results with 2D Strain Echocardiography

The global myocardial function in patients after repair of tetralogy of Fallot (TOF) can be assessed by cardiovascular magnetic resonance (CMR) and measurement of B-type natriuretic peptides. Two-dimensional echocardiography-derived strain and strain rate (2D strain) facilitate the assessment of regional myocardial function. We evaluated myocardial function in 16 children with residual severe pulmonary valve regurgitation and right ventricular (RV) volume overload after TOF repair before, 1month after, and 6months after pulmonary valve replacement (PVR). In 2D strain echocardiography preoperatively, the longitudinal systolic RV strain was reduced (p<0.05). One month after PVR, longitudinal systolic RV strain decreased further (p<0.05), while systolic and early diastolic radial left ventricular strain and strain rate increased (each p<0.05), followed by a return toward preoperative values after 6months. Six months after PVR, preoperatively elevated RV end-diastolic volume (p<0.01) assessed by CMR and N-terminal pro-B-type natriuretic peptide (p<0.05) decreased. In conclusion, the impairment of the regional myocardial after TOF repair and transient changes after PVR can be subtly analyzed by 2D strain echocardiography in addition to the established assessment of myocardial function with CMR and measurement of B-type natriuretic peptide

Uniqueness and bubbling of the 2 dimensional Landau-Lifshitz flow

ISSN:0944-2669ISSN:1432-083

Balloon valvuloplasty of aortic valve stenosis in childhood: early and medium term results

Background: Isolated aortic valve stenosis in childhood is treated by balloon valvuloplasty. The role of independent risk factors for the outcome remains unclear. Material and methods: We analysed the early and medium term outcome of balloon valvuloplasty in isolated aortic valve stenosis in 44 pediatric patients with isolated, severe aortic valve stenosis at an age younger than 18 years, who received a primary balloon valvuloplasty during the last 5 years in our institution. We evaluated the type of aortic valve morphology, age, clinical status, and myocardial function at the time of the intervention as independent risk factor. Results: A significant early relief of the pressure gradient across the aortic valve (P < 0.001) after balloon valvuloplasty was found. This was independent of the aortic valve morphology. Two neonates with a highly stenotic tricuspid aortic valve and severely compromised haemodynamics died within the first 30 days after the intervention. During medium term follow up (mean 22.5 months) we observed a functional deterioration for the stenosis as well as for the insufficiency of the aortic valve. "Symptoms before intervention” is an independent risk factors (P < 0.001) for valvuloplasty failure. Patients at an "age at intervention ≤ 28 days” (P = 0.02) and patients with "reduced myocardial systolic function” (P = 0.01) had a shorter time to reintervention. Conclusions: The type of aortic valve morphology only has a weak predictive value for the outcome of balloon valvuloplasty during medium term follow up. Critical ill neonates with an impaired myocardial function are at a higher risk for valvuloplasty failur

Evolution of paced QRS and QTc intervals in children with epicardial pacing leads

Aims : Permanent ventricular pacing in children is associated with ventricular dysfunction due to asynchronous activation. It is unclear whether paced QRS intervals increase disproportionately over time, which could potentially cause ventricular dysfunction. Methods : A total of 52 children, with bipolar steroideluting epicardial leads implanted at a median age of 5.6 years (0.0-17.4), was analyzed and followed up to 12.2 years (median 3.7). Patients were subdivided in two groups: right (RV, n = 21) and left (LV, n = 31) ventricular pacing. To correct for age, standard deviation scores (Z-scores) for paced QRS and QTc intervals were calculated from published standard-ECG norm-values. As a measure for individual paced QRS and QTc interval changes, a regression slope coefficient (inclinei) was calculated for each patient's course. Results : Mean Z-scores for paced QRS intervals at first and last follow-up were 4.7 ± 1.2 and 4.9 ± 0.9 for group RV, 4.4 ± 1.1 and 4.8 ± 1.1 for group LV. Inclinei of paced QRS (group RV: 0.038 [-0.27-0.12], group LV: 0.147 [-0.05-0.30]; p = 0.07) and QTc intervals (group RV: 0.026 [-0.08-0.06], group LV: 0.023 [-0.04-0.09]; p = 0.63) did not differ between both groups and indicated limited interval changes over time. Conclusion : Neither epicardial pacing of the right nor left ventricle caused disproportionate paced QRS or QTc interval increases over time. An age-related prolongation of the electrical activation unlikely causes ventricular dysfunctio