Quantum collision current in electronic circuits.
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Journal Article↗
Biomedical subjects
R Gebauer
Publications and source records attributed to R Gebauer.
Resynchronization pacing is a useful adjunct to the management of acute heart failure after surgery for congenital heart defects.
The acute hemodynamic effect of atrioventricular (AV) and inter/intraventricular (IV) resynchronization accomplished by temporary pacing using multiple epicardial pacing wires was evaluated in 20 children (aged 3.4 months to 14.0 years) after surgery for congenital heart defects fulfilling the following criteria: (1) presence of AV and/or IV conduction delay, and (2) need for inotropic support. AV resynchronization (n = 13) was achieved by AV delay optimization during atrial synchronous right ventricular outflow tract pacing. IV resynchronization (n = 14) was accomplished by atrial synchronous pacing from the right ventricular lateral wall in 7 patients with right bundle branch block and normal AV conduction and by atrial synchronous multisite ventricular pacing in another 7 patients with previously performed AV resynchronization. Compared with baseline values, AV resynchronization resulted in an increase in arterial systolic, mean, and pulse pressures by 7.2 +/- 8.3% (p <0.01), 8.6 +/- 8.1% (p <0.005), and 6.9 +/- 13.5% (p = NS), respectively. IV resynchronization used either alone or added to previously performed AV resynchronization led to a pressure increase of 7.0 +/- 4.7%, 5.9 +/- 4.7%, and 9.4 +/- 7.8%, respectively (p <0.001 for all). The combined effect of AV and IV resynchronization resulted in a systolic, mean, and pulse pressure increase of 10.2 +/- 5.0% (range 4.0 to 19.1), 8.6 +/- 5.4% (range 0.8 to 14.8), and 15.2 +/- 8.5% (range 6.1 to 33.3), respectively (p <0.001 for all). The increase in systolic arterial pressure after IV resynchronization was positively correlated with the initial QRS duration (r = 0.62, p <0.05) and extent of QRS shortening (r = 0.66, p <0.05). In conclusion, resynchronization pacing led to a significant increase in arterial blood pressure and was a useful adjunct to the treatment of acute postoperative heart failure in patients with AV and/or IV conduction delay.
Adolescent↗
[Aortic reconstruction in neonates with hypoplastic left heart syndrome] .
The surgical technique and tactics of the Norwood operation in neonates with hypoplastic left heart syndrome represent a surgical challenge. The Norwood operation was performed from the midline sternotomy approach, in extracorporeal circulation and deep hypothermic circulatory arrest was used for reconstruction of the hypoplastic aorta. Operation consisted of reconstruction of the "neoaorta" and the aortic arch from the original hypoplastic ascendent aorta, pulmonary trunk and a patch cut from a pulmonary homograft or pericardium, excision of the atrial septum and an arterial shunt from a Goretex vascular graft 3.5 or 4 mm in diameter. In patients with well developed aortic arch it was possible to reconstruct the aorta using Damus-Kaye-Stansel operation without circulatory arrest. Out of 12 operated patients with this defect, two (16.7%) died during the early postoperative period, one patient died late. The postoperative course was often complicated. In 6 (50.0%) patients the second step of Norwood operation, the bidirectional cavopulmonary anastomosis, was performed without mortality. According to our experience, it was necessary to prepare patients adequately before the first surgery. Perfect reconstruction of the aorta and a well functioning shunt had the crucial significance.
Aorta↗
[Initial experience with surgical treatment of tracheal stenosis in small children using extracorporeal circulation].
Severe tracheal stenosis represents a life threatening malformation which necessitates early surgery. Two patients aged one and two years, respectively, were followed-up for signs of congenital stridor. Following respiratory infection both children became critically ill with severe dyspnoea necessitating intubation and artificial ventilation. In the first patient, echocardiography, tracheobronchoscopy and other investigations revealed a pulmonary artery sling with tracheal compression and hypoplasia of the whole trachea. In the second child, presence of a short local tracheal stenosis was found, the cause of which could not be clarified. In the patient with the pulmonary sling, resection and reimplantation of the anomalous left pulmonary artery was performed first. In both children, however, surgical reconstruction of the lower airways was necessary. Surgery was performed from a midline sternotomy approach in extracorporeal circulation. The hypoplastic trachea with circular rings in the first child was enlarged with a pericardial patch. In the second child, the local tracheal stenosis was resected and a direct anastomosis of the trachea was performed. In both patients, transient formation of granulations was observed. Both children, however, survived and their clinical condition remains good 18 and 9 months, respectively, after surgery. Tracheobronchoscopic controls show very good result. Our experience confirms the possibility of successful surgical reconstruction of lower airways in young children using extracorporeal circulation. Good interdisciplinary cooperation between the surgeon and other specialists is an important prerequisite of good surgical results.
Child, Preschool↗
[Primary repair of interrupted aortic arch in neonates].
In the Kardiocentrum, University Hospital Motol, Prague, protocol of the primary repair of interrupted aortic arch was introduced, and between 1993-1997, 15 neonates aged 1-26 days (median 5 days) were operated on. Treatment with prostaglandins E for maintenance of the ductal patency, correction of metabolic acidosis, and treatment of all complications were necessary before surgery. The correction was performed from the midline sternotomy approach, in extracorporeal circulation and deep hypothermia with circulatory arrest. Direct anastomosis between the ascending and the descending aorta was possible in all the patients. At the same time, associated heart lesions were corrected (ventricular septal defect in 13, persistent truncus arteriosus in 3, subaortic stenosis in 2, transposition of the great arteries, double-outlet right ventricle and aortico-pulmonary window in 1 patient, each). Four (26.7%) patients died after surgery. Out of the first 6 neonates 3 (50.0%) died, but out of the subsequent 9 patients only 1 (11.1%) died. Reoperation was necessary in 2 patients. All 11 early survivors are alive and doing well 8-54 months after the repair. In one of them restenosis at the site of aortic anastomosis and hemodynamically significant subaortic stenosis occurred. All the remaining patients have a nonrestrictive aortic anastomosis. Primary repair of interrupted aortic arch and associated heart lesions can be performed in a neonate with reasonable mortality. Treatment of complications is necessary before surgery. Results depend especially on the patient's clinical condition and experience of the center.
Aorta, Thoracic↗
[Treatment of postoperative mediastinitis with sucrose].
The authors describe the treatment of postoperative mediastinitis in cardiosurgery by the open method with local sucrose administration and subsequent delay of closure of the thorax. Universal antibacterial properties of sucrose are made use of. Sucrose dissolves in the wound in its crystalline form and creates a medium with low aqueous activity (high osmolarity), which inhibits bacterial growth. The wound is rapidly cleansed, the secretion from the wound is within 10 days bacteriologically negative and the chest can be closed secondarily. Simple resuture of the wound was performed four times, a plastic operation using the pectoral muscles twice and in one instance it was closed by a plastic operation of the transposed rectus abdominis muscle. The method was used successfully in seven patients.
Administration, Topical↗
Distribution of effective field in the ising spin glass of the +/- J model at T = O. Solutions as superpositions of delta-functions.
The integral equation for the distribution function of effective field of the +/- J random Ising model in the pair (Bethe) approximation is investigated. Its exact solutions at H (magnetic field) = O, T (temperature) = O and for z (coordination number) = 3 expressed as superpositions of 2N + 1 (more than 3), delta functions are considered. Then the integral equation is reduced to a system of algebraic equations of z - 1th degree with N + 1 unknowns. The system of the equations is solved by the Gröbner basis method with N = 1,2,3,4. The number of physically acceptable solutions for a given N is omega(N) + 1, where omega(N) is the number of divisors of N. The ground-state energy and entropy for these are calculated. They are very close in value (entropies are positive), and it is suggested that a number of physically acceptable solutions correspond to local stationary spin-glass states, as discussed in the literatures.
Chemical Phenomena↗