Delayed retrieval of embolized ductal stent: A surgical challenge.

Retrieval of embolized ductal stents from the pulmonary or systemic circulation can be challenging. Most children benefit from surgical shunts in such scenarios. Although early retrieval is advised, stents lodged in the peripheral pulmonary tree can be inaccessible, making the removal complicated. In such patients, stents can be "parked" in the segmental pulmonary arterial branches for retrieval later. In the low-pressure single ventricle pulmonary circulation, partially expanded embolized stents, if left in situ, can precipitate pulmonary arterial thrombosis. This subset of patients may benefit from meticulous anticoagulation and antiplatelet agents. In our case report, we describe the successful extraction of an embolized ductal stent without damage to the right lower lobe pulmonary artery (PA). In the follow-up evaluation, the growth of the right PA is good.

Combined mitral and aortic valve replacement for rheumatic heart disease: fifteen-year follow up and long-term results.

BACKGROUND AND AIM OF THE STUDY: Rheumatic heart disease is the most common cause of multivalvular disease in developing countries. Unless aggressive and timely intervention in the form of valve replacement is pursued, the condition progresses rapidly to disability and death. Combined mitral-aortic valve replacement represents a major technical challenge, and carries high early and late mortality rates. METHODS: The course of 382 consecutive hospital survivors of combined mitral-aortic valve replacement, operated on between January 1992 and December 2006, was reviewed. The valve of choice for the mitral position was the Starr-Edwards (98%), while Medtronic-Hall and St. Jude Medical valves were favored for the aortic position (81%). RESULTS: The mean postoperative follow up was 64.8 +/- 53.9 months, with a total cumulative follow up of 1,792 patient-years (pt-yr); the follow up was 87% complete (n=332). Late death occurred in 29 patients (8.7%). Long-term survival at five, 10 and 15 years was 92%, 78% and 45%, respectively, with a mean survival of 153 months. The linearized rates of thromboembolism, anticoagulation-related hemorrhage and prosthetic valve endocarditis were 1.06, 2.41 and 0.334% per pt-yr, respectively. CONCLUSION: Among the rheumatic population, double valve replacement offers excellent symptomatic improvement and favorable late survival. Hemodynamic superiority and thromboresistance are the normal selection criteria for these prostheses, although the surgeon's experience, and the ease of insertion, availability and cost of the valve also play important roles. A strict adherence to optimal anticoagulation levels optimizes protection against thromboembolism and anticoagulation-related hemorrhage, and helps to provide the patient with a good quality life.

Synthesis of au nanoparticles at "all" pH by H2O2 reduction of HAuCl4.

In this article we report the synthesis of Au nanoparticles (NPs), from HAuCl4, in the pH range of 2.9 to 11.2 using H2O2 as the reducing agent. Ultraviolet-visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction techniques have been used to characterize the Au NPs. UV-Vis spectral observation showed that the Au NPs synthesized in acidic conditions tend to generate particles with absorption maximum around 540 nm. On the other hand the NPs generated at a pH higher than 8.0 generally have broad absorption with maxima occurring beyond 600 nm. Interestingly, TEM analysis showed that the NPs generated at pH lower than 7.0 tend to be smaller and spherical in shape, whereas the particles generated at a pH beyond 7.0 tend to be non-spherical and larger in sizes or agglomeration of small particles. Also, we speculate on the mechanisms of reduction of HAuCl4 by H2O2 under different pH conditions.

A water-soluble polythiophene-Au nanoparticle composite for pH sensing.

In this paper, we report the development of a reversible pH sensor in aqueous medium based on the fluorescence properties of a polythiophene-gold nanoparticle (Au NP) composite. The composite was synthesized in water by simultaneous reduction of HAuCl(4) to Au NPs and polymerization of thiophene in the presence of no additional reagents. It was stable for weeks and had characteristic emissions, which changed in the pH range of 3.0 to 6.0, thus providing a mean for probing the pH of an aqueous solution. Measurement of the pH could be performed over several cycles of titrations, pointing to the robustness of the materials for such sensing applications. The mass spectra of the composite at two extreme pH values were identical, indicating that the primary structure of the polymer was not affected due to changes in pH of the medium. Transmission electron microscopic (TEM) measurements indicated the presence of small sized Au NPs with the polymer in the milieu. The composite could be titrated by acid (or base) and considering the acid-base equilibria at different pHs, we have been able to calculate the pK(eq) of the composite, which was further used in calculating the pH of an aqueous solution from the emission spectrum of the composite. Our approach took advantage of redox chemistry in synthesizing the water-soluble composite and the optical behavior of a conjugated polymer in developing an important pH sensor, which may form the basis of further development of versatile pH or other sensors by suitably modifying the backbone of the monomer.

Electrochemical actuation of growing copper dendrimers in water.

We report the observation of electrochemical actuation in growing dendritic fibers made of self-assembled copper nanostructures (of 100 nm or less in diameter), on the metallic cathode of an ordinary aqueous electrochemical cell. This could be achieved when a copper anode and another metal cathode is placed in aqueous solution of either dilute HCl or CuSO(4), or CuCl(2), or H(2)O, and upon application of a DC voltage in the range of 1.5-12.0 V. The actuation could be observed with an on-off cycle of the applied voltage in the above range. The phenomenon was also observed with the growth of bimetallic structures using a number of electrolytes such as Ag(NO(3)), Pb(NO(3))(2), CoCl(2), NiCl(2), CdCl(2), ZnCl(2), and HAuCl(4). The fibrous structures remained stretched as they grew longer with time in the presence of an applied voltage. The extent of actuation was dependent on the applied voltage, the concentration of Cu(2+) ions in the solution, and also on ions such as Na(+), which did not get deposited at the cathode. The observed phenomena under different conditions have been explained on the basis of electrocapillarity.

Use of extracorporeal life support for emergency coronary artery bypass grafting.

A 14-year old boy was admitted with an anomalous origin of the right coronary artery (RCA) from the left sinus of Valsalva, with an interarterial course of the narrow proximal segment. He underwent coronary ostial augmentation and main pulmonary artery translocation to the left pulmonary artery. In the post-cardiopulmonary bypass (CPB) period, he developed thrombotic occlusion of the RCA resulting in arrhythmia and ventricular dysfunction, requiring extracorporeal life support (ECLS) in the form of extracorporeal membrane oxygenation rather than CPB. After confirming this complication by cardiac catheterization, the right coronary artery territory was revascularized with a pedicled right internal thoracic artery graft. The entire procedure was performed on a beating heart using a stabilizer during ECLS. This strategy may be useful in situations with unstable haemodynamics and a low risk of blood loss.

Secondary repair of Ebstein's anomaly with atrioventricular septal defect using the cone technique.

A nine-year-old boy with incomplete atrioventricular septal defect (AVSD) and Ebstein's anomaly had undergone a closure of primum atrial septal defect and repair of right and left AV valves at four years of age. He presented with severe regurgitation of the right AV valve. He underwent further surgery, and a cone reconstruction of the right AV valve was performed. The association of Ebstein's anomaly with AVSD has been reported only rarely. We present a case of this association treated with the previously unreported application of the cone reconstruction (da Silva repair) as a secondary strategy.

Membrane-directed high bactericidal activity of (gold nanoparticle)-polythiophene composite for niche applications against pathogenic bacteria.

The use of nanoscale materials as bactericidal agents represents a novel paradigm in the development of therapeutics against drug-resistant pathogenic bacteria. In this paper the antimicrobial activity of a water soluble (gold nanoparticle)-polythiophene (AuNP-PTh) composite against common bacterial pathogens is reported. The nanocomposite is broad-spectrum in its bactericidal activity and exhibits a membrane-directed mode of action on target pathogens. The therapeutic potency of AuNP-PTh is demonstrated by experiments which reveal that the nanocomposite can breach the outer membrane defense barrier of Gram-negative pathogens for subsequent killing by a hydrophobic antibiotic, inhibit the growth of model gastrointestinal pathogens in simulated gastric fluid, and significantly eradicate bacterial biofilms. The high bacterial selectivity and lack of cytotoxicity on human cells augers well for future therapeutic application of the nanocomposite against clinically relevant pathogenic bacteria.

Ventricular septal defect closure in a child with osteogenesis imperfecta: risk factors and management.

Cardiac surgery in patients with osteogenesis imperfecta is challenging as the friability of the tissues can be hazardous before, during, and after the operation. A multidisciplinary approach with a planned strategy is essential for the successful management of these patients. We present a 6-year old child with osteogenesis imperfecta, who underwent ventricular septal defect closure without any complication.

Catalytic gold nanoparticle driven pH specific chemical locomotion.

Gold nanoparticle (Au NP) catalyzed decomposition of alkaline hydrogen peroxide has been utilized in driving chemical locomotives in a liquid. Au NPs deposited on spherical micron sized polymer resin beads catalyzed the decomposition of H(2)O(2) in the pH range 9.1-10.8. The O(2) gas bubbles produced in the decomposition moved the beads upward with average velocities that depended on the pH of the solution. The measured average velocity of the bead increased with the increase in pH in the range 9.1-10.8. Above this pH, the self-decomposition of H(2)O(2) produced sufficient bubbles in the medium that made the motion haphazard and thus prevented a clear measurement of the velocity. The observed accelerated motion of the locomotive has been explained by considering the time-dependent growth of O(2) gas bubbles on the polymer, while taking into consideration desorption and other factors.

Intrapericardial diaphragmatic hernia after arterial switch operation.

Intrapericardial diaphragmatic hernia after median sternotomy for cardiothoracic procedures is a rare complication. We describe an interesting case of diaphragmatic hernia in a 6-month-old girl presenting as cardiac tamponade, 4 months after an arterial switch operation. The diaphragmatic defect was iatrogenic and emphasizes the danger of inadvertent diaphragmatic injury during cardiac operations.

Rapid estimation of bacteria by a fluorescent gold nanoparticle-polythiophene composite.

Herein we present a facile method for rapid quantitation of bacterial cells over several logarithmic dilutions. The quantitation is based on loss of the fluorescence intensity of a positively charged Au nanoparticle-polythiophene composite in the presence of bacterial cells. The present method allowed estimation of both Gram-positive and Gram-negative bacteria with cells as low as 1000. Transmission electron microscopic investigations revealed attachment of the composite with bacteria with no discernible change in the morphology of the cells. Further, dynamic light scattering experiments indicated preferential attachment of smaller composite particles over larger ones, which were also attached at higher bacterial concentrations. The ease of operation with minimal sample manipulation steps, high sensitivity, quantitative detection, and its generality offer specific advantages over conventional methods.