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Pulmonary venous return is directed to the aorta via the left ventricle ( red arrow) and systemic venous return is directed to the pulmonary artery via the right ventricle ( blue arrow) leading to an anatomic correction at the arterial level buy augmentin no prescription antimicrobial resistance definition. This leaves the morphologic left ventricle as the systemic ventricle and the mitral valve as the systemic atrioventricular valve discount augmentin 375mg with amex virus respiratorio. Overall survival for the arterial switch operation in the current era can be accomplished P 375 mg augmentin fast delivery virus 3 game online. Thus, anatomic details of the coronary arteries prior to the operation is an important finding for many centers. However, in experienced surgical hands, complex coronary anatomy does not adversely affect the short- or long-term outcomes of the arterial switch operation (56,57,58,59,60). First described by Rastelli in 1969 (62,63), operative mortality in the current era (64) for transposition of the great arteries with ventricular septal defect and left ventricular outflow tract obstruction now approaches 0% with the Rastelli procedure (Fig. A: The operation is performed utilizing hypothermic cardiopulmonary bypass with ascending aortic and bicaval cannulation. The aorta is cross- clamped and the myocardium is protected with intermittent doses of cold cardioplegic solution. B: A right ventriculotomy is used to expose the ventricular septal defect (shaded grey) and create the intracardiac baffle. The pulmonary artery is divided and the pulmonary valve and proximal main pulmonary artery stump are closed. Right ventricle-to-pulmonary artery continuity is established with placement of a valved conduit. Pulmonary venous return is directed from the left ventricle across the ventricular septal defect to the aorta via the intracardiac baffle (Insert: red arrow). Systemic venous return is directed from the right ventricle to the pulmonary arteries via the right ventricle-to-pulmonary artery conduit (blue arrow). This redirects the ventricular outflows and bypasses the left ventricular outflow tract obstruction leaving the morphologic left ventricle as the systemic ventricle and the mitral valve as the systemic atrioventricular valve. Administration of 100% oxygen and performing the hyperoxia test can readily distinguish pulmonary from cardiac pathology due to mixing. Little or no increase in the partial pressure of oxygen on 100% oxygen is seen in patients with transposition of the great arteries and other significant congenital cyanotic heart lesions. Supplemental oxygen should be administered and correction of metabolic derangements and acidosis should be performed. Prostaglandin E1 infusion is critical for adequate mixing in these patients, particularly prior to a balloon atrial septostomy. This allows adequate patency of the duct while at the same time enabling a natural airway to be maintained without apnea and resultant intubation, in most patients. Higher doses of prostaglandin may be needed in some patients if adequate mixing does not occur. Ultimately, most patients will require a balloon atrial septostomy soon after diagnosis for adequate mixing to occur. In many centers, this is performed judiciously on a case-by-case basis, depending on amount of mixing present and timing of surgery. In other centers, most patients undergo a balloon atrial septostomy, which is our preferred approach as well. Performing a balloon atrial septostomy has the advantage of enabling the prostaglandin E1 infusion to be discontinued and allowing the baby to feed prior to the eventual operation. Despite a technically successful balloon atrial septostomy, some newborns may still require prostaglandin E1 infusion for adequate mixing to occur. It is also important to realize that in some patients with transposition of the great arteries with ventricular septal defect, or transposition of the great arteries with ventricular septal defect and left ventricular outflow tract obstruction, adequate mixing may not occur at the ventricular level. In some of these newborns, a balloon atrial septostomy may need to be performed to promote adequate mixing at the atrial level. An arterial switch operation should be delayed for at least a few days to allow the pulmonary vascular resistance to drop prior to exposure to cardiopulmonary bypass. We and other centers advocate for a slightly delayed arterial switch operation before 1 to 2 weeks of age with excellent outcomes (58,59,60). A slightly delayed operation allows many children to feed and allows the pulmonary vascular resistance to drop even further prior to placement on cardiopulmonary bypass. Others have found early arterial switch operations advantageous, and delay beyond 3 days of age to be associated with higher hospital costs and more morbidity (57). Patients presenting late can undergo an arterial switch operation prior to 60 days of age (59), although this may be not be possible in all infants. After this time frame, left ventricular reconditioning by placing of a pulmonary artery band (with or without a systemic to pulmonary artery shunt) before an eventual arterial switch operation, or the use of a left ventricular assist device after the arterial switch operation may be needed (70). Children presenting extremely late (still seen in developing countries), may not be able to have their left ventricle reconditioned (beyond the age of 12 years) (71). In such patients, the only surgical option may be an atrial redirection procedure. Patients with transposition of the great arteries and ventricular septal defect should be operated before the first 6 weeks (58) to 3 months of life (59), prior to the development of pulmonary vascular obstructive disease, or sooner, should signs of congestive heart failure not be controlled medically. Timing of operative repair for patients with transposition of the great arteries, ventricular septal defect and left ventricular outflow tract obstruction, depends on the physiology and anatomic details of each individual patient. Operations for many patients can be delayed for months, depending on the degree of left ventricular outflow tract obstruction. If a Rastelli operation is to be performed, this provides the advantage of placing a larger right ventricle to pulmonary artery conduit with a longer freedom from reintervention or reoperation for right ventricle to pulmonary artery conduit dysfunction. Some patients may need interval placement of a systemic to pulmonary artery shunt (e. In some cases, with favorable anatomy, an arterial switch procedure with ventricular septal defect closure and removal of the substrate for left ventricular outflow tract obstruction can be performed early on. Operative and Interventional Catheterization Approaches Balloon Atrial Septostomy The report of the balloon atrial septostomy by Rashkind and Miller in 1966 was a landmark event in the field of interventional cardiology (2). In addition to anatomic details of the atrial septum, it is important to rule out juxtaposition of the atrial appendages, particularly left juxtaposition of the right atrial appendage. In this anomaly, the right atrial appendage is positioned leftward and posterior, and the operator can be mistaken (particularly if using fluoroscopy only) that the balloon is in the left atrium, when in fact it is in the right atrial appendage (37). If not recognized, this will result in an ineffective septostomy or potentially serious/catastrophic damage to the juxtaposed right atrial appendage. The procedure can be performed with or without intubation, depending on the clinical status of the baby. Nowadays, the procedure is most often performed at the bedside with transthoracic echocardiographic guidance. Rarely fluoroscopy may be needed if the defect is difficult to cross (late presentation with thick atrial septum) and one anticipates using static balloon dilations or other complex specialized maneuvers. Biplane fluoroscopy should be used if fluoroscopy is to be used, and transthoracic echocardiography can be used as an adjunctive imaging technique. Access can be obtained via the femoral vein or umbilical vein, each having its own advantages and preference for each route of access being operator dependent.
Plain flms may demonstrate graphically as a multiloculate fuid collection in the central the calculus responsible for the obstruction order augmentin 375mg with mastercard antibiotics for sinus infection contagious. However purchase augmentin 375 mg with visa bacteria in the stomach, as echo complex discount augmentin 625mg bacteria unicellular or multicellular, caused by pooling of urine within the dis parts of the ureter overlie the transverse processes of the tended pelvis and calices (Fig. As the distension vertebrae and the wings of the sacrum, the calculus may be becomes more severe, the dilated calices can resemble mul impossible to see on plain flm. Following injection of intra tiple renal cysts, but dilated calices, unlike cysts, show con venous contrast medium, a flm of the renal tract is taken tinuity with the renal pelvis (Fig. If the urogram is normal, obstruction, thinning of the cortex due to atrophy will be with contrast seen in normal, undistended ureters bilater seen. If one of the ureters is obstructed, then a but overlying bowel often obscures dilatation of the mid dense nephrogram will be seen and opacifcation of the and distal ureter. If the obstruction is at the level of the pelvicaliceal system and ureter on the obstructed side takes vesicoureteric junction, the distal ureter can usually be much longer. In time, the collecting system and the level or a stone at the vesicoureteric junction), it is often not pos of obstruction can usually be demonstrated (Fig. The left kidney shows a very dense nephrogram which is characteristic of acute ureteric obstruction. Computed tomography is now widely used to evaluate urinary tract obstruction (Fig. Chronic obstruction Calculi are by far the commonest cause of obstruction of by tumour, either within the renal collecting system or by the urinary tract. The imaging techniques are described an external tumour causing compression, may be visual above. A sloughed papilla in papillary necrosis is a rare 244 Chapter 8 P P P P (b) (a) U Fig. There is obstruction of the right kidney with dilatation of the pelvicaliceal system, reduced cortical enhancement and some loss of cortical thickness, suggesting that the obstruction may be longstanding. Intravenous contrast is seen in the left renal pelvis but not in the obstructed right renal pelvis. In the case of tuber Urinary Tract 245 retic can be given during a renogram (Fig. If there is obstruction, the radionuclide accumulates within the kidney and renal pelvis, whereas with a baggy pelvis there is rapid washout of the radionuclide from the suspect kidney. Carcinoma of the cervix, ovary and rectosigmoid colon and malignant lymph node enlargement are frequent * causes of ureteric obstruction. The ureters may be visibly deviated by the tumour but, frequently, the ureteric course is normal. Because some of these tumours originate in the midline or are bilateral, both ureters may be obstructed. In most cases, no cause can be found for this benign fbrotic condition, which encases the ureters and causes obstruction. When frst seen, only one side may be obstructed but, eventually, the condition becomes bilateral. There is an abrupt change in calibre at kidneys and inferiorly to involve the pelvic side walls. Most solitary masses arising within the renal parenchyma are either malignant tumours or simple cysts. Other causes of a renal mass include: renal abscess, any age but it is usually discovered in children or young benign tumour (notably oncocytoma or angiomyolipoma), adults. Often, the ureter cannot be the central part of the kidney (sometimes called a ‘renal identifed at all; if it is seen, it will be either narrow or pseudotumour’ or column of Bertin) may produce the normal in size. This dis • multiple simple cysts tinction can be made by giving a diuretic intravenously. Frusemide was given at 10 minutes and in the case of the ‘baggy’ pelvis resulted in rapid washout of radioactivity from the kidney. Some cysts contain low level echoes in their depend Renal masses are usually frst detected at ultrasound exam ent portions, presumably due to previous haemorrhage. Ultrasound can establish whether a mass When the ultrasonographer is sure that the diagnosis is a is a simple cyst and can, therefore, be ignored, or whether simple cyst, no further investigation is needed. Indeterminate the lesion is solid and, therefore, is likely to be a renal car lesions with both cystic and solid components need further cinoma. They are flled with clear fuid and thus demon Solid renal masses have numerous internal echoes of strate no echoes from within the cyst. Because sound is attenuated during its echoes from the front and back walls of the cyst and a passage through a solid lesion, the back wall is not as sharp column of increased echoes behind the cyst, because of as that seen with a cyst, and there is often little or no acous increased through transmission of the sound, known as tic enhancement deep to the mass. Both kidneys are surrounded by dense fbrosis, infltrating the perinephric fat (arrows). When all of these criteria are met, the diagnosis of simple cyst is certain and there is no need to proceed further. They are benign tumours, which rarely cause problems, although, on occasion, they cause signifcant retroperitoneal haemor rhage. The attenuation value of renal tumours on scans without intravenous contrast enhance ment is often fairly close to that of normal renal paren chyma, but focal necrotic areas may result in areas of low density, and stippled calcifcation may be present in the interior of the mass as well as around the periphery. The degree and appearance of any solid compo noted that any solitary mass in a young child, or any mass nent within the cyst infuences the risk of the lesion being that contains visible calcifcation, particularly if the calcif malignant. Depending on the clinical circumstances and on cation is more than just a thin line at the periphery, is likely the imaging appearances, the clinician may opt to follow to be a malignant tumour. The mass in the right kidney (long arrow) shows substantial enhancement and is invading the anterior wall of the right renal vein (short arrow). These additional scan planes help to demonstrate I the anatomical relations of the mass to the renal hilar vessels and may help in planning partial resections of the kidney. Urothelial tumours (b) Almost all tumours that arise within the collecting systems of the kidneys are transitional cell carcinomas. Most urinary stones contain visible calcifcation, and Threedimensional reformatting of the collecting system virtually all calcifed flling defects are stones. If clot is a possibility, then followup to check for resorption of the clot may be helpful. Ultrasound may help to differentiate between from organisms that enter the urinary system via the a radiolucent stone and tumour, as the calculus demon urethra. In adults, only selected patients require ultrasound and plain flms may diagnose underlying imaging. In acute pyelone Most patients with acute urinary tract infection do not phritis the ultrasound is either normal or demonstrates require urgent imaging investigations. In patients present diffuse or focal swelling of the kidney, with diminished ing with signs of infection associated with pain, particu echoes due to cortical oedema. Following resolution of the acute episode, imaging of the renal tract is undertaken in women with recurrent infec tions or after a single confrmed urinary tract infection in (b) men. Investigation of the renal tract is indicated in all children with a confrmed urinary tract infection.
