By K. Delazar. Emory & Henry College.
Histologic features tract of taste buds Nervus Facial intermedius nerve Petrosal ganglion Glossopharyngeal nerve Nodose ganglion B generic vytorin 30 mg visa. Gustatory Pathways Vagus nerve Figure 15-1 Schematic diagram of gustatory pathways order 30mg vytorin amex. Projections The axons of these ganglia cells enter the from the gustatory cortex to the lateral posterior brainstem purchase discount vytorin on line, pass into the solitary tract, and syn- orbital gyri, where they overlap with the olfactory apse in the solitary nucleus, which enlarges in the system, are associated with favor. From this parvicellular part, Humans are microsmatic, that is, their sense fbers travel in the gustatory radiation through of smell is poorly developed; hence, the sense the posterior limb of the internal capsule to the of smell and its pathways are considerably less Chapter 15 The Gustatory and Olfactory Systems: Ageusia and Anosmia 199 Gustatory radiation Ventral posteromedial nucleus Secondary gustatory tract Nervus intermedius Geniculate ganglion Facial nerve Solitary nucleus (gustatory) Glossopharyngeal nerve Inferior (petrosal) ganglion Vagus nerve Solitary tract Inferior (nodose) ganglion Figure 15-2 Three-dimensional dorsal view of gustatory pathways. The olfactory neurons are bipolar and tral nervous system structures associated with number several million on each side. Each neu- olfaction form the rhinencephalon “nose-brain,” ron possesses a dendrite that extends to the sur- which chiefy includes the olfactory structures on face where it expands to form a bulbous olfactory the base of the brain and the ventromedial parts vesicle. Each of these vesicles, in turn, gives rise of the temporal lobe in the vicinity of the uncus. These cilia spread over the surface of the olfactory mucosa and are bathed in mucus secreted mainly Olfactory Receptors by specialized glands and by cells in the olfactory The primary olfactory neurons are located in epithelium and the neighboring nasal mucosa. Posterior limb, internal capsule medulla 1 Figure 15-3 Transverse sections showing the relations of gustatory central pathways. There may be as many as 1,000 receptors span of these neurons is only 4 to 8 weeks, and, responsive to different odorant stimuli. Odorant on degenerating, new neurons are formed from receptor binding is transduced to a depolariza- undifferentiated basal stem cells in the deeper tion of the primary olfactory neuron by activa- part of the olfactory epithelium. These nonmyelinated fbers are Chapter 15 The Gustatory and Olfactory Systems: Ageusia and Anosmia 201 Mitral cell Rectus gyrus Olfactory bulb Olfactory tract Olfactory glomerulus Cribriform plate Olfactory nerve of ethmoid Olfactory axon Basal stem cell Olfactory neuron Supporting cell Bulbous olfactory vesicle Olfactory cilia Figure 15-4 Histologic features of olfactory receptors, nerves, and bulb. The synaptic contacts the foramina in the cribriform plate of the eth- between the olfactory nerve fbers and the moid bone. Collectively, these bundles form the mitral cells are made via dense arborizations olfactory nerve, and they terminate in the olfac- that form the olfactory glomeruli. In these tory bulb located on the foor of the anterior structures, thousands of olfactory nerve fbers cranial fossa above the cribriform plate. It is mainly com- posed of the efferent fbers of the bulb, although Clinical it does contain clumps of neurons that form the Connection anterior olfactory nucleus as well as centrifugal fbers from the contralateral anterior olfactory The sudden loss of smell (anosmia) nucleus and from neurons in the basal fore- is not uncommon after sudden brain whose axons modulate the olfactory bulb blows to the head. However, the of the tract diverge to form two bundles, the gradual loss of smell may be related to the lateral and medial olfactory striae, which bor- growth of a tumor at the base of the anterior der the anterior perforated substance. The fbers cranial fossa; hence, this type of loss should be of the medial olfactory stria arise chiefy in the investigated. The The olfactory bulb is the fattened oval medial olfactory stria becomes buried in the ante- structure on the orbital surface of the frontal rior perforated substance shortly after emerging lobe near the anterior end of the olfactory sul- from the olfactory trigone. The lateral olfactory stria from the uncus to the hypothalamus for the carries the olfactory impulses from the olfactory mediation of the behavioral and autonomic bulb toward the insula where they bend medi- responses to odors. On entering the temporal lobe, the fbers of the lateral olfactory Clinical stria terminate in the primary olfactory cor- Connections tex, which includes the piriform cortex (the area medial to the rhinal sulcus), the uncus, Lesions in the olfactory area of the and the adjacent entorhinal cortex. The uncus orbitofrontal cortex result in the is the enlargement in the anterior part of loss of ability to discriminate different odors. These olfactory hallucinations com- the amygdaloid nucleus, which sends axons to monly occur in temporal lobe epilepsy and fre- the medial dorsal nucleus of the thalamus. The quently constitute the aura that precedes the medial dorsal nucleus, in turn, sends axons to phenomenon referred to as “uncinate fts. In addition to the olfactory tical areas converge in the orbitofrontal cortex connections destined for the orbitofrontal where there appears to be a center that integrates cortex, olfactory sensations are transmitted smell and taste thereby producing favor. Chapter 15 The Gustatory and Olfactory Systems: Ageusia and Anosmia 203 Radiographic imaging reveals fractures Chapter Review of the basilar skull. Several days later, the Questions patient reports there is no “taste” to his food and cannot detect any odors in his 15-1. The most likely structure damaged and what are their peripheral distributions that could cause these defcits would be: and central connections? The two main neuronal cell types are the language abilities, and all other higher mental pyramidal and granule cells (Fig. The axon proceeds from the base of the cell and in most cases leaves the cortex to reach There are three types of cortex in the human brain: other cortical areas or subcortical nuclei. The neo- pyramidal cells are the chief cortical efferent or cortex appeared last in evolution and constitutes output neurons. The paleo- cortex is restricted to the base of the cerebral hemi- spheres and is associated with the olfactory system, Clinical whereas the archicortex, the phylogenetically old- Connection est cortex, makes up the hippocampus. Both the paleocortex and archicortex are parts of the limbic The surfaces of the dendrites of system, which is described in Chapter 17. It contributes about half During postnatal maturation of the cortex, the the total brain weight and consists of a sheet of pyramidal cell dendritic trees expand and the neurons 2. The fnding that with only about one-third of the neocortex found the faulty development of these dendritic trees on the surface and the remainder buried in the and their spines is seen in cases of mental retar- grooves between the convolutions. A fold or con- dation such as Down syndrome suggests that volution is called a gyrus (pl. The long association bundles give fbers to and receive fbers from the overlying gyri along their routes. The four types: intracortical, association, commissural, superior longitudinal fasciculus is located above and subcortical (Fig. Sweeping around the insula is the arcuate fasciculus, which connects the frontal Intracortical Fibers and temporal lobes. Chapter 16 The Cerebral Cortex: Aphasia, Agnosia, and Apraxia 209 Arcuate loop Parietal lobe Occipital lobe Superior longitudinal fasciculus Frontal lobe Insula Uncinate fasciculus Inferior occipito- frontal Temporal lobe Arcuate fasciculus Figure 16-3 Three-dimensional drawing of the major association bundles dissected from the lateral aspect. Those fbers (inferior) part of the frontal lobe with the ante- of the splenium located in the lateral wall of the rior part of the temporal lobe both of which have atrium and posterior horn of the lateral ventricle limbic system functions. Cortical connections of the beneath the cingulate and parahippocampal gyri, anterior commissure include the inferior and mid- components of the limbic lobe. Commissural Fibers Clinical Commissural connections occur between homo- Connection logous areas of the two hemispheres. Two major bundles exist: the corpus callosum and the ante- Surgical transection of the corpus rior commissure (Fig. The corpus cal- callosum is sometimes performed losum is divided, from anterior to posterior, into for the relief of epilepsy. The ros- patients have served to elucidate the impor- trum and genu interconnect the anterior part of tance of the corpus callosum, especially for the frontal lobe (Fig. Median brainstem showing locations of hemispheric commissural fbers: the corpus callosum and anterior commissure. Plane of horizontal section through genu and splenium of corpus callosum (line 1-1). Chapter 16 The Cerebral Cortex: Aphasia, Agnosia, and Apraxia 211 C Trunk of corpus callosum Frontal or parietal gyri Lateral fissure Middle temporal gyrus Inferior temporal gyrus Frontal section Anterior commissure Amygdaloid nucleus Figure 16-4 (Continued) C. Plane of coronal section through corpus callosum and anterior commissure (line 2-2). The major corti- adjacent part of the posterior limb contain cofugal projections are described with the motor corticopetal projection fbers from the motor system (Chapters 6 to 9).
Some experts recommend that most or all patients with staphylococcal infection or prosthetic valve infection early after implantation should undergo valve replacement order genuine vytorin. Indications for operative intervention include significant valvular obstruction order vytorin without a prescription, progressive heart failure secondary to valvular insufficiency or dehiscence order vytorin overnight delivery, fungal endocarditis, persistently positive blood cultures after appropriate antibiotics for 10 to 14 days, bacteriologic relapse after an appropriate course of therapy, and recurrent major emboli. Less definite indications for surgery include a single major embolus, echocardiographic demonstration of a large vegetation, and extension of infection to an annular abscess or a myocardial abscess. This sentiment was confirmed as a preferred approach in a large survey of cardiologists and infectious disease specialists published in 2005 (35). Endocarditis can often be prevented by repairing the underlying cardiac defect or reducing the likelihood of bacteremia. For the above patient groups, prophylaxis is limited to dental procedures that involve manipulation of gingival tissue or the periapical region of teeth or perforation of the oral mucosa. There are situations for which prophylaxis is not appropriate, such as routine anesthetic injections through noninfected tissue, taking dental radiographs, placement of removable prosthodontic or orthodontic appliances, adjustment of orthodontic appliances, placement of orthodontic brackets, or shedding of deciduous teeth and bleeding from trauma to the lips or oral mucosa. While these procedures should be discouraged, and if undertaken they should be performed under sterile conditions, antibiotic prophylaxis for the prevention of endocarditis is not recommended. The antibiotic should be administered as a single dose 30 to 60 minutes before the procedure. Amoxicillin is the drug of choice for children who can take oral medications and who are not allergic to penicillins. The risk of acquiring endocarditis may change after surgical or other reparative procedures. The guidelines emphasize the importance of maintenance of good oral health as an important factor in preventing endocarditis in susceptible individuals. Clinicians are urged to educate their patients/parents in this regard and to frequently remind them of this need. New criteria for diagnosis of infective endocarditis: utilization of specific echocardiographic findings. Proposed modifications to the Duke criteria for the diagnosis of infective endocarditis. Infective endocarditis in infants and children during the past 10 years: a decade of change. A cost-effectiveness analysis of bacterial endocarditis prophylaxis for febrile children who have cardiac lesions and undergo urinary catheterization in the emergency department. Risk factors for in-patient mortality during infective endocarditis in patients with congenital heart disease. Infective endocarditis: diagnosis, antimicrobial therapy, and management of complications. Frequency of infective endocarditis among infants and children with Staphylococcus aureus bacteremia. Comprehensive diagnostic strategy for bold cultures-negative endocarditis: a prospective study of 819 new cases. Two-dimensional echocardiographic assessment of infective endocarditis in children. Role of echocardiography in evaluation of patients with Staphylococcus aureus bacteremia: experience in 103 patients. Penetration of the atrioventricular septum by spread of infection from aortic valve endocarditis: early diagnosis by transesophageal echocardiography and implications for surgical management. Infective endocarditis in children: clinical analysis and evaluation of two diagnostic criteria. Are the Duke criteria superior to the Beth Israel Criteria for the diagnosis of infective endocarditis in children? Value and limitations of the von Reyn, Duke, and modified Duke criteria for the diagnosis of infective endocarditis in children. Clinical Practice Guidelines by the Infectious Diseases Society of America for the treatment of methicillin resistant Staphylococcus aureus infections in adults and children. Guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group. Temporal trend in infective endocarditis in the context of prophylaxis guideline modifications: three successive population-based surveys. Incidence of infective endocarditis in England, 2000–13: a secular trend, interrupted time-series analysis. Although chest pain is common in patients presenting to pediatric cardiology clinics, myocardial ischemia is rarely ever the etiology. The list of etiologies leading to myocardial ischemia is potentially long and each diagnosis for the most part is uncommon. Unfortunately, many patients who suffer an ischemic episode do not present until after myocardial injury or infarction has already happened. The patient who presents with symptoms of chest pain before an event or in the middle of an event will be the focus of this particular chapter. A detailed history, clinical examination, and appropriate diagnostic testing should lead to the correct diagnosis and offer the ability to include or exclude myocardial ischemia from the differential diagnosis. For the purposes of this chapter we will not review atherosclerotic coronary artery disease, it is covered in Chapter 71. Definition Myocardial ischemia is an imbalance between myocardial oxygen supply and demand. Left untreated, it results in angina pectoris, myocardial stunning, myocardial hibernation, or under the most severe instances, acute coronary syndromes like myocardial infarctions. Myocardial ischemia can be caused by several mechanisms, including increased myocardial oxygen demand in the presence of a severe fixed stenosis, coronary spasm due to local release of vasoactive mediators, and transient thrombus formation. The determinants of myocardial ischemia are likely to differ in patients with unstable coronary syndromes as the underlying pathologic substrate usually consists of plaque rupture with a varying degree of intracoronary thrombus formation (1,3,4). In normal conditions, an uninterrupted flow of large quantities of oxygenated blood to the myocardium is critical to its normal function. During systole, this flow can be abolished or even reversed toward the epicardial vessels. The blood must flow from low-to-high intramyocardial pressure in order to meet the metabolic demands of each layer. Flow must be regulated in such a way that areas of high demand can immediately increase their blood supply. The myocardium extracts about 60% to 75% of oxygen from the blood that passes through it. Because of this high level of extraction, coronary sinus blood has low oxygen tension, generally around 25 to 35 mm Hg. This low level of oxygen tension requires that any increase in oxygen demand be met by an increase in blood flow rather than an increase in extraction (5,6). There are two main mechanisms by which myocardial ischemia can occur: (a) a reduction in myocardial supply of oxygen, and (b) an increase in myocardial oxygen demand.
Adequate reversal of heparin with protamine is dependent on knowing the correct heparin concentration buy cheap vytorin 30 mg on-line. Too little protamine means heparin is still circulating or excessive unbound protamine has anticoagulant properties (102 order vytorin 20 mg,103) order vytorin 30mg with mastercard. Management of Postoperative Bleeding Although some bleeding from indwelling mediastinal drains is expected after cardiac surgery, the rate of bleeding should decrease as each postoperative hour goes by. Excessive bleeding is a clinical concern that warrants immediate attention and constant vigilance. In the immediate postoperative period, bleeding of <5 mL/kg/h is often associated with minor abnormalities in coagulation status. Red cell transfusion may be necessary to correct a postoperative anemia but blood component administration is rarely necessary. Bleeding 5 to 10 mL/kg/h should prompt notification of the cardiothoracic surgeon and continued evaluation of the patient at the bedside. The patient must be closely monitored for persistence or an increase in the rate of bleeding that may signal the presence of a surgical bleeding site or may be the result of loss of coagulation factors secondary to the ongoing hemorrhage. Bleeding of >10 mL/kg/h that persists or increases will likely result in hemodynamic compromise if not abated. The cardiothoracic surgeon should decide whether reexploration is needed to exclude a bleeding site or to remove thrombus that may be perpetuating further bleeding. The primary end point, time to chest closure, was actually prolonged in the treatment group. No difference was noted in the secondary end points of surgical blood loss or use of blood products (113). Much work has focused on the diagnosis, treatment, and prevention of thrombosis in Kawasaki disease (115,116,117,118,119,120,121,122,123,124,125) and to a lesser extent on the thrombotic complications associated with cardiac catheterization (126,127,128,129,130,131,132,133,134,135,136) and cardiomyopathies (137,138,139,140,141). The prevention and management of thromboses related to prosthetic valves (142), arrhythmias (143,144), and pulmonary hypertension (145,146,147,148,149,150) in children has largely been extrapolated from the adult literature. For the past decade, the single-ventricle population has been identified as a particularly high-risk population for thrombosis and their potentially devastating sequelae (151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167). Two recent endeavors have highlighted that much work is still needed in the area of diagnosis, treatment, and most importantly in further defining risk factors so that potentially life-threatening thrombotic complications can be prevented in children and adolescents with heart disease. The American Heart Association commissioned a writing group to critically review and summarize the available data on thrombosis in this patient population, and to make recommendations when appropriate. In 2012, the National Heart Lung and Blood Institute convened a Working Group to explore issues relevant to thrombosis in children with heart disease. They emphasized the need for a more fluid approach to grading evidence that recognizes that sources of high-quality evidence may differ in this population, and that extrapolation of evidence from cohort, population, and mechanistic studies may be useful despite the lack of classic randomized controlled trials. The Propensity for Thrombosis in Children and Adolescents with Congenital and Acquired Heart Disease Congenital and acquired heart disease put children and adolescents at risk for thrombosis mainly because the triad of risk factors for thrombosis initially described by Virchow (170) in 1856 is often at play. These factors are (a) stasis of blood flow, (b) hypercoagulability, and (c) endothelial injury. Altered blood flow In addition to the potential of static flow, children with heart disease may have turbulent blood flow and/or flow across prosthetic surfaces, both of which may predispose to thrombus formation making “altered blood flow” a more applicable category than “stasis of blood flow” alone in this patient population: a. Stasis: may occur in dilated heart chambers as well as in dilated native or prosthetic outflow tracts. Turbulent flow: may occur across stenotic native or prosthetic heart valves, stents, intracardiac devices, and/or obstructed native or prosthetic outflow tracts activating platelets either directly (172) or by increasing sheer stress that can result in platelet activation independent of endothelial damage (173). Thrombin generation is increased via the extrinsic system in response to cytokines, ischemia, sheer stress, and activated platelets and via the contact system in response to the contact of blood with the circuit. The procoagulant state may persist well into the postoperative period (175,176,177,178). Coagulation abnormalities have been identified to include altered coagulation protein levels, increased thrombin generation potential, decreased endogenous inhibitors of coagulation, and decreased fibrinolytic proteins among others. Such coagulopathies were first identified in children and adolescents with a Fontan circulation but more recently have been found in children through all stages of single-ventricle palliation and also in children with acyanotic and acquired heart disease (151,153,155,160,161,164,179,180,181,182,183,184). Although of great interest, there is a paucity of data on the predictability of hypercoagulability panel testing in prospectively identifying children at risk for postoperative thrombosis (161,163). This may be exacerbated by iron deficiency anemia which makes red cells more ridged and less deformable as well as by dehydration (153,168,185). Endothelial injury and dysfunction: occurs from turbulent flow on endothelial surfaces as well as from vessel wall endothelial damage from insertion and persistence of central lines and catheters. Endothelial injury exposes tissue factor and subendothelial collagen stimulating platelet aggregation and coagulation at the site of injury. Inflammation and bloodstream infection Inflammation and the potential of blood stream infection are further risk factors for thrombosis in many children with heart disease. In addition, tissue factor has been documented to become accessible via activated monocytes or endothelial cells through cytokine production during inflammation or when stimulated by sepsis (174,186). In recent clinical studies, sepsis was associated with increased thrombus formation especially in the presence of an indwelling central venous catheter (188,189,190). Children with heart disease especially infants with single-ventricle disease appear to be particularly vulnerable, often carrying these derangements well beyond the perioperative period. Consequence of Significant Thrombi in Children and Adolescents with Cyanotic Heart Disease Children and Adolescents with cyanotic heart disease are at particular risk of devastating complications from both venous as well as arterial thrombi. Occlusion of systemic-to-pulmonary shunts or Fontan circuits are both lethal without immediate intervention. Post-catheterization arterial or venous thrombotic occlusions may make performance of further essential diagnostic and/or therapeutic cardiac catheterizations difficult or impossible. Occlusion of large veins of the upper body may make it impossible for a single-ventricle patient to go on to a bidirectional cavopulmonary anastomosis or to a Fontan palliation, rendering transplant the only long-term option. Common Thrombotic Complications in Congenital Heart Disease: Prevention, Diagnosis, and Treatment Table 75. Recently there has been much interest in the novel oral anticoagulants dabigatran, a direct thrombin inhibitor, and the factor Xa inhibitors rivaroxaban, apixaban, and edoxaban. The advantage of the novel anticoagulants is that routine laboratory monitory is not required. The disadvantage is that there currently are no specific antidotes for major bleeding complications in children. Neonates and infants are at particular risk (164,191), because of an immature coagulation system that has a low capacity to inhibit clot formation and a high resistance to anticoagulation. In addition, the vessel to catheter diameter ratio is lower in neonates and infants compared to older children and adolescents making clotting more likely. Overall, there is a paucity of information on the true scope of thrombotic complications in children and adolescents after cardiac surgery. Two retrospective studies and two prospective studies have reviewed thrombotic incidence and risk factors in cardiovascular surgical populations. Deep venous thrombosis associated with indwelling central lines was the most common type and site of thrombus.
An iodine impregnated is likely to compromise development of the left pulmonary adhesive plastic drape is applied to seal the closure vytorin 20mg generic. Because of the complexity of the neonatal surgery it is age discount vytorin 20 mg, although there may be a higher incidence of pleural effu- particularly important to have a high index of suspicion for the sions order discount vytorin, which are very rarely seen with this procedure in older various problems which are not infrequently seen in patients infants and children. It is also important to recognize that the a possible long-term risk after the frst-stage procedure is the infant is likely to outgrow a Sano shunt earlier than a Blalock development of regurgitation of the neoaortic valve (i. This fnding, per se, eterized by 4–5 months of age; this recommendation stands is not a current indication to proceed to a bidirectional cavo- irrespective of clinical progress. The repair involves application of prin- pulmonary artery dilation in the Sano shunt group. The neoaorta is reconstructed utilizing a period of deep hypothermic circulatory arrest in exactly the same fashion as nomic status, obstructed pulmonary venous return, smaller described above. However, the distal divided main pulmonary ascending aorta, genetic syndrome, and lower gestational artery is not closed. Although some have suggested that the subgroup with aortic Bypass is recommenced when the neoaorta has been cannu- atresia and mitral stenosis does worse, for example Vida et al. Interrupted pledgetted horizontal mattress 5/0 in the short term with the Sano shunt. When a era, early and 2-year mortality rates were 23% (14/62) and femoral vein homograft is used it is not necessary to supple- 52% (32/62); in the Sano era, early and 2-year mortality rates ment the proximal anastomosis with a hood of glutaralde- were 6% (2/32) and 19% (6/32). The Pediatric Heart Network, an affliation of several major centers in North America, conducted a prospective randomized trial to the hyBrid Procedure address this issue. Although the hybrid procedure has been enthusiastically adopted by a small number of centers, Wernovsky et al. In 2010, with other forms of single ventricle with systemic outfow Honjo and Caldarone reported that hybrid palliation yields obstruction. Neonates undergoing the Norwood procedure equivalent but not superior stage 1 palliation survival and were randomly assigned to the Blalock shunt (275 infants) or comparable 1-year survival to conventional Norwood pallia- the Sano shunt (274 infants) at 15 North American centers. The repair involves a combination of principles of the Norwood procedure and Rastelli procedure and is known by some as the Yasui procedure. The ductus will be ligated and divided and the proximal descending aorta, aortic arch and ascending aorta are opened as for the Norwood procedure. They did however describe need for reintervention for left pulmonary artery stenosis secondary to compression by the neoaorta. By 18 months from the time of the Norwood procedure 58% of patients had outcomes for 253 patients who underwent the Norwood pro- undergone a bidirectional Glenn shunt (Fig. Mortality was strongly infu- fully achieved a third-stage Fontan circulation within 6 years enced by the presence of associated noncardiac congenital of the bidirectional Glenn shunt. Mortality for the third stage conditions as well as severe preoperative obstruction to pul- was 9% and 3% of patients underwent cardiac transplanta- monary venous return (p = 0. Risk factors for death after the bidirectional Glenn ond-stage hemi-Fontan procedure or bidirectional Glenn was shunt included younger age at the time of the shunt and the 97% and survival following the Fontan procedure was 88%. Hospital mortality was 47% between improved dramatically since the Norwood operation was ini- 1992 and 1996 but between 1996 and 2001 hospital survival tially introduced in 1983. The authors emphasize the value of continuous described 25 neonates who had undergone various modifca- monitoring of systemic venous oxygen saturation as a factor tions of the frst-stage reconstructive procedure at Children’s which improved their stage 1 Norwood survival. Of those who deVeloPmentAl outcome died, one was a preterm neonate weighing less than 2 kg and two were neonates who could not be adequately resuscitated Wernovsky et al. Report of the rence of perioperative seizures were predictive of subopti- New England Regional Infant Cardiac Program. The pre- Bayley scale was 91 and the Mental Developmental Index sentation of symptomatic heart disease in infancy based on 10 was 88. Both of these scores should be greater than 100 in years’ experience (1973–1982): implications for the provision a normal population. Prostaglandin E1 fnd a direct association between these suboptimal scores in infants with ductus arteriosus-dependent congenital heart and technical aspects of the procedure it is important to rec- disease. J Thorac Cardiovasc Surg involved an asanguineous prime resulting in a hematocrit of 1980;79:462–3. Mean duration of circulatory arrest was syndrome: natural history in a geographically defned popula- tion. Disturbed myocardial connexin 43 and N-cadherin expres- sions in hypoplastic left heart syndrome and borderline left Norwood procedure discharge and age 12 months (p < 0. J Thorac prospective study of neurodevelopmental outcome and perfu- Cardiovasc Surg 1984;88:620–6. There were no statistical differences in mental artery connections with the hypoplastic left heart: a 4-year development or psychomotor development scores between prospective study: incidence, echocardiographic and clinical the groups at pre-second-stage operation or 1-year follow-up, features. Similar results have been nary artery arising from the pulmonary artery in hypoplas- 77 tic left hearts: case series and review of literature. Semin Thorac Cardiovasc Surg Pediatr Card brain anomalies associated with the hypoplastic left heart syn- Surg Annu 2011;14:35–7. Am J operative brain injuries do not worsen with surgery in neo- Cardiol 1972;30:450. Mitral atresia associated with pulmo- syndrome: experience with palliative surgery. J Am Coll the arterial duct and banding of the pulmonary arteries: basis Cardiol 1986;7:361–5. Mechanical in a fetus with normal nuchal translucency and abnormal duc- durability of pulmonary allograft conduits at systemic pres- tus venosus blood fow at 13 weeks of gestation. Semin Thorac Cardiovasc Surg Pediatr Card tic stenosis in the neonate: a multi-institutional study of man- Surg Annu 2002;5:104–15. Semin Thorac Cardiovasc Surg Ped Card planning for fetuses with complex congenital heart disease. Lessons learned from the devel- of minimal cerebral capillary fow during retrograde cerebral opment of a new hybrid strategy for the management of hypo- perfusion: an intravital fuorescence microscopy study in pigs. World J Ped Congen Heart Surg surveillance program prevents interstage mortality after 2010;1:161–2. Survival after mortality and cardiac transplantation in infants with single reconstructive surgery for hypoplastic left heart syndrome: ventricle lesions: risk factors and their interaction with shunt a 15-year experience from a single institution. Current status of staged reconstruction for hypo- for patients with the mitral stenosis-aortic atresia variant of plastic left heart syndrome. Two-year survival and men- left heart syndrome: lessons learned from 115 consecutive tal and psychomotor outcomes after the Norwood procedure: patients. In hypoplas- Neurodevelopmental outcome of patients after the Fontan tic left heart patients is Sano shunt compared with modifed operation: a comparison between children with hypoplas- Blalock-Taussig shunt associated with deleterious effects on tic left heart syndrome and other functional single ventricle ventricular performance? Hypoplastic left of deep hypothermic circulatory arrest in cardiac transplant heart syndrome: consensus and controversies in 2007. Hybrid palliation for neonates with patients with hypoplastic left heart syndrome treated with hypoplastic left heart syndrome: current strategies and out- heart transplantation. Infuence of sur- opmental outcome in children with hypoplastic left heart gical strategies on outcome after the Norwood procedure.
Assuming that the transgene integrated before the ﬁrst cell division order cheap vytorin on-line, the pups should be heterozygous for the transgene buy vytorin with mastercard. Inbreeding of the heterozygotes will generate homozygous individuals rat growth hormone was microinjected into the pronuclei of fertilized mouse eggs (Palmiter et al order vytorin. Of 21 mice that developed from the injected eggs, seven carried the fusion gene and six of these grew signiﬁcantly larger than their littermates. At 74 days of age, the transgenic mice weighed up to 44 g, while their non-transgenic littermates weighed approximately 29 g. The technique has also been used to attempt to produce therapeutic proteins within transgenic animals. It cannot be used to delete genes (knock-out), or to alter existing genes within the genome. That is, the offspring of highly expressing parent animals may show considerably different levels of expression. In some cases, this may be due to altered genomic methylation patterns at the site of the transgene (Palmiter, Chen and Brinster, 1982). This happens when integration of the transgene is delayed until after the ﬁrst cell division. They can be cultured in vitro by growing them in a dish coated with mouse embryonic skin cells that have been treated so they will not divide. Unlike most other animal cells, they can be maintained in culture, through successive cell divisions, for long periods. The blastocyst is then implanted into the uterus of a pseudo- pregnant female and pups produced. The chimeric pups are then crossed with wild-type animals to generate true heterozygotes, which can then subsequently be inbred to create a homozygote. This means that targeted transgenes can be produced in which speciﬁc genes of the genome are either deleted or altered (Thomas and Capecchi, 1987). Cells containing the tk gene may be killed by treatment with ganciclovir, which is phosphorylated by thymidine kinase, and then undergoes further phosphorylation by cellular kinases. If, however, homologous integration has occurred, then the tk gene will be lost and cells will survive ganciclovir treatment (Mansour, Thomas and Capecchi, 1988). In addition to supplying a mechanism to delete genes (knock-out), speciﬁc genes may also be replaced with mutated versions of themselves. The ability to speciﬁcally knock out genes can provide an immensely powerful approach to assigning gene function in whole animals, especially the mouse (Osada and Maeda, 1998). Perhaps more importantly, knockouts can provide excellent model systems for the analysis of human disease. We have previously discussed the potential difﬁculties with this type of analysis in other organisms (Chapter 10), and many of the same problems can also be encountered with animal knock-outs. The deletion of the molecular chaperone hsp47 is lethal to mouse embryos, predominately as a function of defective collagen biosynthesis (Nagai et al. The deletion of the tumour suppressor gene p53 results in the formation of mice that develop normally, but are exquisitely sensitive to spontaneous tumours early in their lives (Donehower et al. The deletion of Matrilin 1, an extracellular matrix protein that is expressed in cartilage, yields transgenic mice with no apparent phenotype in comparison to their wild-type counterparts (Aszodi et al. A lethal phenotype generally reﬂects the earliest non-redundant role of the gene, and precludes an analysis of an analysis of gene function later in devel- opment. The diploid nature of higher organisms means that mutants that fall into this class may be analysed in their heterozygous (+/−) state. Knock-outs that fall into the last category (no observable phenotype) may arise as a result of genes acting in parallel pathways compensating for each others’ functions. It is also possible that the techniques are simply too crude to detect any subtle differ- ences between the wild-type and the knock-out animals. The complexity of animal genomes also means that a knock-out may have a profound effect in one strain of mouse, but quite a different effect in another. Ideally, knockout experiments should be performed in a variety of strain backgrounds, but the length of time required to do that, and the costs involved, often preclude this analysis. One problem with this type of approach for producing transgenic ani- mals, which we have seem previously when looking at engineering in plants (Chapter 11), is that the selectable maker gene is transferred to the transgenic animal. The high-level expression of an antibiotic-resistance gene within a transgenic animal is generally undesirable. The expression of the marker may induce the abnormal expression of other neighbouring genes, and the potential for transfer of the marker gene to non-transgenic animals should be avoided. There are many instances where the expression of an inserted transgene is required only in a speciﬁc tissue or set of cells. This can readily be achieved by constructing the foreign gene such that it is under the control of a tissue- speciﬁc promoter. Such an approach works well, provided that a suitable tissue-speciﬁc promoter is available (Table 13. Conditional knock-outs can also be produced, again using the loxP-Cre site-speciﬁc recombination system (Gossen and Bujard, 2002). If, for example, the knock-out of a gene results in an embryonic-lethal phenotype, then it may be necessary to delete the gene from the genome after the animal has been born. Adapted from Lewandoski (2001) Promoter Gene normally Tissue or cells Reference controlled of expression Alb Albumin Liver (Postic et al. In addition, the transgenic animal is also modiﬁed to carry a copy of the gene encoding the Cre recombinase under the control of an inducible promoter, e. Mx1 is part of the mouse viral defence system and is transcriptionally inert in healthy mice (Hug et al. Rather than constructing a transgenic mouse containing both the tissue- speciﬁc promoter expressing the Cre recombinase and the target gene sur- rounded by loxP sites, a series of transgenic mice have been constructed that each contain a different tissue-speciﬁc promoter controlling the expressing of Cre. These can then be used as a ‘bank’ of mice strains to which transgenic mice containing a particular ﬂoxed gene can be crossed. Mating these strains will result in the formation of progeny in which the gene in inactivated only in those tissues that express Cre (Gu et al. This means that a single transgenic ﬂoxed gene can be deleted in a variety of tissues without having to resort to further in vitro manipulation. The tetracycline-inducible expression system (see Chapter 8) may be used to drive Cre expression to regulate knock-out function. In the absence of tetracycline, the Cre gene is expressed and will induce site-speciﬁc recombination between two loxP sites. In the presence of tetracycline, the Cre gene will not be expressed and recombination will not occur (St-Onge, Furth and Gruss, 1996). If the nucleus of a differentiated cell is introduced into an enucleated egg then, under appropriate conditions, the nucleus can become ‘reprogrammed’ such that development of the animal reoccurs.
Check on both the coronal and para- sagittal scans that the cell that you have identifed has the expected amount of opacifcation order online vytorin. This cell is followed in each sequen- tial coronal scan and is again identifed on the parasagit- tal by again using all the information available (Fig purchase vytorin 30 mg fast delivery. There are no other cells associated with the second cell in this ex- ample but buy discount vytorin 20mg online, if there were, they would be identifed in the same manner and a building block would be placed for each additional cell. In this example we have a large agger tion between it and the frontal drainage pathway is not nasi cell (broken black arrow) and a type 3 frontal ethmoidal cell (broken white arrow). It is often con- fused with the frontal sinus drainage pathway especially can be safely and competently cleared. This sequential identifcation of each cell frst turbinate is, in most cases, the agger nasi cell10,18 (Fig. Place a building block for this cell in your three-dimensional marked with a white arrow. This cell (type 1) is identifed on the parasagittal scan and a building block placed for it directly above the agger nasi cell. A building block is also placed for the small bulla ethmoidalis cell below the suprabullar cell. If instruments are passed along pathways, and this can be done very gently without However, it is not just the cellular construction and their re- undue force or pressure, cell walls can be fractured safely lationship with one another that is important but also the clearing the drainage pathway of the frontal sinus without drainage pathway of the frontal sinus around these cells. Frontal Recess and Frontal Sinus Sequential axial scans are viewed starting in the frontal sinus and progressively following the frontal sinus drainage path- The Type 1 Cellular Confguration way into the frontal recess. As the axial scans are followed inferiorly, the A type 1 (T1) confguration is one frontal ethmoidal cell T1 cell in the frontal recess comes into view (axial scan I in above the agger nasi cell (Fig. Note the change in shape of the frontal sinus dur- single cell associated with the agger nasi cell is common but ing the transition from the frontal sinus to the frontal recess also may induce signifcant variability into the frontal recess. The lower During this transition the anterior wall (beak) also becomes building block is the agger nasi cell and the upper block rep- more bowed in the region of the nasion (Fig. In this ex- ample the drainage pathway is pushed posteriorly between the suprabullar cell and the T1 cell. During the dissection of The Type 2 Cellular Confguration the frontal recess instruments (probes or curettes) are passed along this pathway and the identifed cells fractured to clear A type 2 (T2) confguration consists of two or more fron- the pathway. However, when the pathway is anterior, care above the agger nasi cell and push the implantation of the needs to be taken when fracturing the cell wall posteriorly uncinate higher on the lamina papyracea (Fig. For removing residual bony fragments a through-cutting confrm the position and placement of these cells. Instruments should not be passed the T2 frontal ethmoidal cells do not reach above the frontal through the roof of a cell because, occasionally, the surgeon beak and therefore do not migrate into the foor of the fron- may be confdent that he or she is in a cell with space between tal sinus and removal of these cells does not involve the fron- the roof of the cell and the skull base; but, if mistaken, and tal ostium. Most cells that appear as isolated frontal sinus cells sifed as type 3 (T3) cells (Fig. If the section where are frontal bulla cells that have pneumatized along the skull the frontal sinus becomes the frontal recess is reviewed base into the frontal sinus and protrude from the posterior (Figs. A T4 cell is a frontal to the frontal recess occurs when the continuous bony line ethmoidal cell that pneumatizes through the frontal ostium that forms the foor of the frontal sinus disappears. For the and extends more than 50% of the vertical height of the fron- cell to be pushing into the foor of the frontal sinus, the cell tal sinus (Fig. T3 cells are usually found in the lateral aspect of the frontal sinus ostium and push the Clinical Diference between T3 and T4 Cells drainage pathway medially and narrow (obstruct) the drain- age pathway of the frontal sinus (white arrow, Fig. The If we assume that with very few exceptions all apparent bony beak can be visualized forming the foor of the frontal isolated frontal sinus cells originate in the frontal recess sinus on the left side of Fig. In addition, on the parasagittal scan, a cell can be a recent article17 we suggested that it is worthwhile to seen above the bulla (suprabullar cell) that almost touches discriminate between very extensive pneumatization of the K3 cell as it pneumatizes forward. This creates a narrow- a frontal ethmoidal or bulla frontalis cell and a cell which ing of the frontal outfow track. The frontal beak (foor of the frontal sinus) is the the right side pushing into the foor of the frontal sinus. The three- bony continuity marked by the white broken arrow in the coronal scan dimensional (3D) reconstruction illustrates the T3 cell pushing into (A) and by the “beak” in the 3D reconstruction. If the cell tize extensively into the frontal sinus may require additional extends further than 50% of the height of the frontal sinus on access (combined approach, endoscopic modifed Lothrop/ the coronal scans then the cell is a T4 cell (by our defnition) frontal drillout, or osteoplastic fap)14,17 for removal to be rather than a T3 cell (Fig. On review of the patients included in that study17 not be able to be removed from below unless the frontal os- we suggested it would be clinically relevant to create an tium was particularly large in its anteroposterior dimension. Further discussion on the selection and techniques used to normal handheld instruments may not be possible. In these remove T3 and T4 cells (and frontal bulla cells) is to be found patients we do not advocate drilling this septum as the drill in Chapter 7. They become frontal bulla cells when they migrate through the In the preceding pages the various cellular confgurations frontal ostium into the frontal sinus. Although it is vital to determine the number forms the roof of these cells and they are seen on the para- of cells in the frontal recess and their relationship to the sagittal to hug the skull base as they migrate into the frontal frontal ostium, it is equally important to understand how sinus (Fig. In the following examples the cellular confgura- clinical importance of these cells is that they push the drain- tion is frst established and then for each confguration the age pathway of the frontal sinus anteriorly and, to be re- drainage pathway is determined. Once the drainage pathway moved, the curette or probe needs to be passed anterior to has been identifed, the surgeon can work out where to slide their wall and the cell wall carefully fractured in a posterior the frontal sinus probe or curette so that the cells can each direction. Intersinus Septal Cells (Video 17) T1/T2 Variations These are cells associated with the intersinus septum of the frontal sinus. This cell pneumatizes from the frontal T1/T2 Confguration with a Posterior Drainage Pathway recess through the frontal ostium and its medial wall is (Video 19) the intersinus septum of the frontal sinus. The next cell seen in the may not be possible to fracture this wall and removal with coronal scans sits directly above this agger nasi cell and the 6 Anatomy of the Frontal Recess and Frontal Sinus 63 A B C D Fig. The bulla ethmoidalis cell is seen on the parasagittal and a block placed for this cell. The frontal sinus drainage pathway on into the frontal recess around the cells in the frontal recess. Building blocks are placed for both these cells frontal sinus into the frontal recess are presented in conjunc- (Fig. The next step is to work out how the frontal sinus drains The frst two steps were to construct a 3D picture and to around these cells. This is a crucial step as it will determine place the drainage pathway in this 3D picture. The combined where the surgeon places instruments during the surgical 3D reconstruction is presented in Fig. Typically the surgeon will be faced with several If the surgeon had created a 3D mental picture of the anat- potential drainage pathways once the agger nasi cell has been omy before the surgery, he or she would have visualized that removed. When looking into the frontal recess, he or she needs after the agger nasi cell had been removed, that the T1 cell to know if the pathway is posterior/medial/lateral or anterior as would be visible in the medial region of the frontal recess, this will determine where the probe or curette is placed. Once and that the frontal sinus drainage pathway would be visible this instrument is slid up the pathway the obstructing cells can posterior to this cell. In this example the T1/2 cell occupies the entire anterior region of the frontal recess and pushes the drainage pathway This is one of the more common confgurations where the T1/ posteriorly.
In these settings vytorin 20mg amex, many vytorin 30mg mastercard, if not most purchase vytorin 20 mg mastercard, of the affected individuals are unaware of their disease and therefore do not receive secondary prophylaxis (4,27). With the exception that chorea is more common in girls, there is no definite gender predisposition (47,48,49,50). Third, studies indicate a familial predilection (54,55) and a higher concordance rate between identical twins than in fraternal twins (44% vs. Streptococcal pharyngitis occurs most commonly in children aged 5 to 15 years, and is uncommon before the age of 2 years. Other investigators subsequently found that some strains were associated with pharyngitis while other strains were associated with skin infections (72). The M protein is thought to be a major virulence factor because it affects the ability of host cells to undergo phagocytosis. Further evidence of the importance of the M protein came from the discovery that epitopes of the M protein molecule cross-react antigenically with human heart and brain tissue. A few studies have failed to confirm this association, possibly related to population differences. Only 30% to 40% of patients with acute mitral regurgitation have a persistent murmur at follow-up, with most of the clinical improvement occurring in the first 6 months after the acute illness. The pathologic changes in rheumatic carditis are primarily perivascular and interstitial, without evidence of myocyte necrosis. The “exudative” phase occurs in the first 2 to 3 weeks after disease onset and is characterized by interstitial edema, cellular infiltration (T cells, B cells, macrophages), fragmentation of collagen, and scattered deposition of fibrinoid (eosinophilic granular material). The Aschoff nodule is a perivascular aggregation characterized by a central area of fibrinoid change (altered collagen) surrounded by or infiltrated by large multinucleated (“owl eye”) cells. Pericarditis Grossly, the pericardial surface may have a white, fibrinous, stringy to shaggy exudate; all cases show lymphocytic and mononuclear infiltration of the pericardium. Pericarditis heals with no significant adhesions, and constrictive carditis rarely occurs. Histologically, the myocardium may be edematous and show nonspecific inflammation. However, different from other forms of myocarditis, there is usually no evidence of cell damage. A variable degree of interstitial fibrinoid degeneration with inflammatory foci consisting of lymphocytes, macrophages, and other inflammatory cells has been reported as a common finding (141). Endocarditis Endocardial inflammatory changes are responsible for valvulitis and are therefore the most clinically significant. Small, 1 to 2 mm, friable, fibrinous, verrucous vegetations may occur on the atrial surface of the mitral valve or on the ventricular side of the aortic valve at sites of valve closure (144). With time, granulation tissue may occur, with thickening and eventually fibrosis of the valve. Similarly, chordal inflammation may be followed by granulation tissue, fibrosis, and eventually chordal fusion. Macroscopically, acute rheumatic mitral valvulitis results in elongation (or even rupture) of the chordae to the anterior mitral valve leaflet and annular dilation, resulting in altered leaflet coaptation, the potential for prolapse of the anterior leaflet, and mitral regurgitation (145,146). Vasculitis Generalized vasculitis, in particular involving the coronary arteries and the aorta, has been described (148). It resembles changes of hypersensitivity angiitis, but rarely results in tissue damage or clinical manifestations. Duckett Jones in 1944 (149), these criteria have undergone four revisions or modifications, the last in 1992 (150,151,152,153,154). Revisions and modifications have increased the specificity but decreased the sensitivity of the criteria to avoid overdiagnosis. The latest Updated Jones Criteria were published in 1992 and are intended to be used to establish the initial attack of P. The major criteria are polyarthritis, carditis, chorea, a characteristic rash called erythema marginatum, and subcutaneous nodules. Special Writing Group of the Committee on Rheumatic Fever, Endocarditis, and Kawasaki Disease of the Council on Cardiovascular Disease in the Young of the American Heart Association. Rheumatic fever diagnosis, management, and secondary prevention: a New Zealand guideline. Australian Guideline for Prevention, Diagnosis, and Management of Acute Rheumatic Fever and Rheumatic Heart Disease. In Australia, the guidelines define different criteria for diagnosis in high-risk groups (see Table 59. On the other hand, steroids are of no therapeutic value in patients with chronic rheumatic valvular disease, and might delay more appropriate treatment. The Australia criteria for diagnosing a recurrence are 2 Major, or 1 Major + 1 Minor, or 3 Minor criteria + evidence of a preceding strep infection (171). In New Zealand, the criteria for diagnosing a recurrence are 2 Major, or 1 Major + 2 Minor, or several Minor + evidence of a preceding strep infection (169) (see Table 59. Of the major Jones criteria, migratory polyarthritis is most common, affecting 40% to 70% of cases (Table 59. Importantly, the presentation and evolution of the joint manifestations may be affected by administration of anti-inflammatory medications (aspirin or other nonsteroidal anti-inflammatory agents). It is noteworthy that in some parts of the world, monoarticular arthritis is a common mode of presentation (155,173). In some cases, the joints may be involved sequentially and simultaneously rather than in a migratory pattern, with a new joint becoming involved while a different joint is at a different phase of inflammation and resolution. Although carditis and arthritis commonly occur together, the severity of the joint and heart involvement tend to be inversely related (129). The reasons for this inverse relationship are unclear; some have speculated that joint involvement leads to earlier medical attention and initiation of anti- inflammatory treatment, thus preventing more severe cardiac involvement. Because of the different latency periods between the preceding streptococcal pharyngitis and the onset of symptoms, polyarthritis and chorea uncommonly occur simultaneously (174). In fact, lack of clinical response and improvement within 2 to 3 days should prompt consideration of alternative diagnoses (154,175). It is worth noting that a small subset of patients relapses once or twice after a 6-week course of antirheumatic therapy (176,177). The Jones criteria often fail to exclude other causes of febrile polyarthritis (48), and an alternative diagnosis may be made only as more chronic findings develop (i. Of particular importance is the fact that some patients thought to have poststreptococcal reactive arthritis have shown evidence of cardiac involvement (179,180,182,183). Conversely, a recent study showed no increased risk of valvular heart disease in a series of adults with poststreptococcal reactive arthritis (184). Given the uncertainty with respect to the risk of valvular heart disease for children with poststreptococcal reactive arthritis, some experts recommend that such patients undergo echocardiographic evaluation, receive secondary prophylaxis for up to a year after onset, and possibly undergo a follow-up echocardiogram after a year (185), but this is clearly an area of debate requiring further study. Chorea First described in the late 17th century, the association of chorea and rheumatism was not recognized until the 19th century. It is now known that the clinical manifestations of Sydenham chorea occur due to neuropathologic changes and inflammation in the basal ganglia, cerebral cortex, and the cerebellum (48,189).