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The aim of this study was to evaluate the association of bicuspid aortic valve on contemporary outcomes, including reoperation rates, after one-stage correction for interrupted aortic arch with ventricular septal defect or for aortic coarctation with hypoplastic aortic arch and ventricular septal defect.
Seventy-four consecutive patients (35 boys, 47% and 39 girls, 53%) with interrupted aortic arch (n = 41, 55%) or aortic coarctation with hypoplastic aortic arch (n = 33, 45%) with ventricular septal defect underwent early one-stage correction. Twenty (27%) patients had bicuspid aortic valve, and the remaining 54 (73%) had a tricuspid aortic valve. The median aortic valve annulus diameter was 6.0 mm (IQR: 2.0). Patients’ median age was 7 ± 29 days (range, 2–150); median weight was 3.3 ± 0.7 kg (range, 1.5–6.0), with 21 (28%) patients <3.0 kg. Selective brain perfusion through the innominate artery and selective coronary perfusion through the aortic root during aortic arch reconstruction were used in all patients. Statistical analysis was performed using SPSS version 20.0 software (SPSS Inc., Chicago, IL, USA).
The early mortality was 1.3%. One premature neonate died in the hospital with extracorporeal membrane oxygenation after aortic coarctation plus ventricular septal defect repair. There was no further mortality. Median follow-up was 5.7 years (IQR: 10.48). Reinterventions occurred in 36 (49%) patients: balloon angioplasty in 18 (24%) patients, reoperations in 4 (5%) patients, and both in 14 (19%) patients. A total of 86 follow-up procedures were required in these 36 (49%) patients: aortic valve valvulopasty (n = 6, 8%), stent implantation (n = 8, 11%), balloon dilatation (n = 39, 53%), and reoperation (n = 33, 45%). The median time to reinterventions was 9.094 years (SE 0.890). A potential risk factor for reintervention after interrupted aortic arch and aortic coarctation with ventricular septal defect repair was bicuspid aortic valve (p = 0.019, Chi2 (1) = 5.457). In addition, a multivariate Cox analysis with backward selection and significance level <0.015 was applied to all variables that showed significant effects in univariable analyzes. This regression confirmed that bicuspid aortic valve (HR = 0.381, p = .016), and interrupted aortic arch (HR = 0.412, p = 0.043) were predictors of late reintervention. All patients had no obvious neurologic impairment in routine examinations at last follow-up.
Bicuspid aortic valve was a significant risk factor for valve-related reintervention after one-stage repair for aortic arch obstruction with ventricular septal defect due to later development of stenosis associated with higher late morbidity and mortality. Particularly neonates with bicuspid aortic valve will possibly require reintervention in the future. Regular lifelong cardiac follow-up is recommended.
Myocardial bridging is a congenital coronary artery anomaly in which the coronary artery has a partly “tunnelled” intramyocardial course. This tunnelling leads to compression of the affected vessel segment during ventricular systole. It is considered to be a benign variation of the norm in about 25% of the population caused by an aberrancy of embryologic coronary development. The bridging is also thought to cause severe cardiac conditions in a few of those affected. The series of six young patients presented here is the largest series so far to report on symptomatic myocardial bridging in children with different underlying heart diseases. All patients recently presented to our centre with signs of myocardial ischaemia. They subsequently underwent coronary angiography, which revealed myocardial bridging of the ramus interventricularis anterior. In all patients, therapy with β blockers was started to reduce heart rate and myocardial contractility. β Blocker treatment was also given in order to prolong diastole and improve coronary artery blood flow. Two patients underwent surgical exposure of the involved coronary segment: a 2-year-old boy because of recurrent, severe myocardial ischaemia in combination with a reduction of general health, changes in ST-segments, and the presence of a dilative cardiomyopathy; and a 13-year-old girl because of evidence of myocardial ischaemia during exercise testing after surviving sudden cardiac death. Surgery was successful and recovery was complete and uneventful. The presented series shows that myocardial bridging can be symptomatic and may require urgent treatment and even surgical intervention in early childhood in rare cases.
This paper presents a scheme of terahertz (THz) radiation generation based on beating of two flat-topped laser beams by different frequencies and the same electric field amplitudes in actual plasma with spatially periodic density that electron–neutral collisions have been taken into account. Flat-topped laser beams have the exclusive features such as steep gradient in distribution of laser intensities, wider cross-section in comparison with other profiles, which make stronger ponderomotive force and lead to stronger nonlinear current and hence, THz radiation of higher field. The effects of laser and plasma parameters on THz radiation generation are investigated analytically. It is shown that by increasing the order of flatness of incident laser beams, because of their steep gradient, good enhancement in emitted THz radiation take place. It can be deduced that by increasing beating frequency, efficiency of THz generation decreases which can be compensated by manipulating in density ripple magnitudes. The intensity of the emitted radiations is found to be highly sensitive to the order of flatness. Based on the results of this paper, optimization of laser and plasma parameters can increase the efficiency of THz radiation generation strongly.
This paper presents a scheme of terahertz radiation generation based on beating of two dark hollow laser beams with different frequencies, the same electric field amplitudes, in actual plasma with spatially periodic density that electron–neutral collisions have taken into account. The main feature of considered hollow laser beams is, having the same power at different beam orders. Because of special distribution in beam intensity gradient in dark hollow laser beam, the produced terahertz radiation has special field profile. The effects of laser and plasma parameters on terahertz radiation generation are investigated analytically. It can be deduced that by increasing beating frequency, efficiency of terahertz generation decreases which can be compensated by manipulating density ripple magnitudes and dark-size adjusting parameter. The intensity of the emitted radiations is found to be highly sensitive to the beam order. Based on the results of this paper, optimization of laser and plasma parameters can increase the efficiency of terahertz radiation generation strongly.
A case of left main coronary artery stenosis is presented in a boy late after an arterial switch operation, with significant ischaemia during exercise with good collateralisation through the right coronary artery. The problem was successfully managed with minimally invasive off-pump coronary artery bypass through median re-sternotomy.
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