Left Heart Disease Pulmonary venous hypertension may be caused by increased pressure distal to the pulmonary capillaries to the left ventricle purchase levitra plus with amex erectile dysfunction drug therapy. Left heart disease in adults is common order levitra plus 400mg with amex erectile dysfunction medication cheap, particularly in the later part of life and is mainly due to left ventricular diastolic dysfunction order generic levitra plus line impotence at 30 years old. However, in children, structural heart disease, such as in Shone complex or borderline left ventricular physiology, is the most common. Firstly, there is a passive increase in pulmonary artery pressure as downstream pressure increases to maintain left-sided preload and cardiac output. Secondly, there is reflex vasoconstriction of the pulmonary arteries or veins or both. Despite surgical-, medical-, and catheter-based attempts, often these therapies are ineffective with recurrence of disease and no cure (57,337,338,339,340,341,342,343,344,345). Using a multimodality approach to the treatment of patients with pulmonary vein stenosis, incorporating sutureless surgical repair, catheter interventions, and adjunctive chemotherapy, early survival may be improved. Complications include hypoxic pulmonary vasoconstriction causing increased pulmonary artery pressures and can lead to right ventricular hypertrophy and failure. However, the development of cor pulmonale carries a poorer prognosis for reversibility. Treatment of cor pulmonale depends on the precise etiology of lung disease, as well as disease severity. Nocturnal oxygen administration may alleviate hypoxia, typically without causing hypercapnia. The introduction of prenatal steroid use, surfactant therapy, new ventilator strategies, and aggressive management of the patent ductus arteriosus, changed the clinical course and outcomes of premature newborns. Survival rates were 64% ± 8% at 6 months and 53% ± 11% at 2 years after diagnosis of pulmonary artery hypertension. Pulmonary artery hypertension and small birth weight for gestational age were associated with worse survival rates. Pulmonary venous hypertension or pulmonary hypertension due to left heart disease. This includes an extensive evaluation for chronic reflux and aspiration, structural airway abnormalities (such as tonsillar and adenoidal hypertrophy, vocal cord paralysis, subglottic stenosis, and tracheomalacia), and assessments of bronchoreactivity (352). Management of children with pulmonary vein stenosis is difficult as catheter-based interventions or surgery have shown poor long-term results and overall survival is poor with the 2-year survival rate from diagnosis of 43% (338). Treatment with afterload reduction and diuretics may show benefit in this select group (359). However, the condition can occur rarely, and an accurate diagnosis is essential for treatment (26,363,364). Predisposing factors include an indwelling central line, collagen vascular diseases, thrombophilia, bacterial endocarditis, and ventriculoatrial shunt for the treatment of hydrocephalus. Likewise, the use of oral contraceptive agents may cause hypercoagulability, leading to pulmonary thromboembolic phenomena. A similar approach should be considered for children who develop this condition despite the relative paucity of data on this procedure in the pediatric age group. Therapy in adults is evidence based whereas in children it is frequently based on experience. Numbers above the bars indicate the percentage of patients with pulmonary hypertension. Pulmonary vascular disease in bronchopulmonary dysplasia: pulmonary hypertension and beyond. Prospective analysis of pulmonary hypertension in extremely low birth weight infants. The three major pathways (endothelin-1, nitric oxide, and prostacyclin) involved in the regulation of pulmonary vasomotor tone are shown. Endothelial dysfunction results in decreased production of endogenous vasodilatory mediators (nitric oxide and prostacyclin) and the upregulation of endothelin-1, which promotes vasoconstriction and smooth muscle cell proliferation. Advances in therapeutic interventions for patients with pulmonary arterial hypertension. Repeat cardiac catheterization is recommended within 3–12 mo after initiation of therapy to evaluate response or with clinical worsening (Class I; Level of Evidence B). Genetic testing is indicated for risk stratification (Class I; Level of Evidence B). Antibiotic prophylaxis for the prevention of subacute bacterial endocarditis in cyanotic patients and those with indwelling central lines (Class I; Level of Evidence C). Pediatric pulmonary hypertension: Guidelines from the American Heart Association and American Thoracic Society. The number in each group (brackets) and the predicted survival out of a possible 5 years is depicted. A positive response is defined by assessing the change hemodynamic parameters to vasodilators. The younger the child at the time of testing, the greater the likelihood of acute pulmonary vasodilation in response to vasoreactivity testing (155,367,368). Many oral and inhaled vasodilators have been used for testing vasodilator responsiveness (202,216,367,368,369,370,371,372,373,374,375). Digoxin is used in the presence of right ventricular failure, although there are no clear-cut data regarding its effectiveness in children (376). Diuretics are used to treat peripheral edema or ascites in the presence of right heart failure, however, excessive diuresis should be avoided. Careful attention to respiratory tract infections is required as they may worsen alveolar hypoxia, and routine influenza vaccination is recommended. In children who require the use of oral contraceptive agents either for prevention of pregnancy or for regulation of menses, we recommend agents that have no estrogen content. Pulse oximetry and polysomnography are indicated and chronic hypoxemia or nighttime desaturation is aggressively treated. However, oxygen therapy is not used as a mainstay of therapy in children with normal daytime saturations. Although the use of chronic anticoagulation has not been studied widely in children, it is usually recommended. The use of anticoagulation in patients with Eisenmenger syndrome is controversial and the potential risks and benefits of anticoagulation in this setting must be carefully weighed (246). Vasoreactivity Testing As in adults, cardiac catheterization with acute vasodilator testing is essential prior to selecting targeted therapy in children. Cardiac catheterization carries a greater risk in those children with baseline suprasystemic pulmonary arterial pressure (odds ratio = 8. Because adults treated with calcium channel blockers began to fail this therapy, Sitbon established more stringent criteria for defining acute vasoreactivity in adults. Although the more strict criteria are used in children, this has not been adequately studied in this population. In both children and adults without post-tricuspid valve shunts, acute vasoreactivity is associated with improved survival independent of the used criteria (32,156,384). Calcium Channel Blockers The use of calcium channel antagonists to evaluate vasoreactivity is dangerous, as these drugs can cause a decrease in cardiac output or a marked drop in systemic blood pressure (363). Such deleterious effects may be prolonged due to the relatively long half-life of calcium channel blockers.
Recently there has been increased use of the Melody transcatheter pulmonary valve to address conduit obstruction/incompetence in the right ventricular outflow tract position order 400mg levitra plus amex homeopathic remedy for erectile dysfunction causes. Although endocarditis and Melody stent fracture with re-stenosis are known complications buy discount levitra plus on-line erectile dysfunction causes uk, thrombosis in the absence of endocarditis has not been reported to date either in vivo or from explanted Melody pulmonary valves (233 buy levitra plus 400mg cheap erectile dysfunction drugs cost comparison,234). As discussed above, tricuspid valve replacement is rare, with Ebstein anomaly being the most common indication. Thrombosis has been reported in a Melody valve placed in a stenotic bioprosthetic tricuspid valve (238). Since there is a paucity of data on the efficacy and safety of anticoagulation strategies for prosthetic valves in children and adolescents, most centers and experts in the field follow the guidelines established for adults by the American College of Cardiology and the American Heart Association revised in 2014 (142) and those of the American College of Chest Physicians published in 2008 (239). Warfarin is currently the mainstay of prophylactic therapy for mechanical valves, although stable, long-term anticoagulation is difficult especially in infants and young children because of developmental hemostasis as well as concomitant medications and certain foods and formulas which may enhance or diminish the anticoagulant effect. Infants are generally at higher risk of prosthetic valve thrombosis because of the smaller size of the prosthesis and difficulties in achieving stable anticoagulation with warfarin therapy. Partial valve occlusion should be suspected in children with signs of low cardiac output, respiratory distress, hepatomegaly, pleural effusions, and/or pulmonary edema. Transthoracic echocardiography may reveal an increased inflow gradient across the valve and decreased leaflet mobility. Fluoroscopy is often used to evaluate valve motion and is felt to be the gold standard by some. Therapy depends on the extent of the thrombus (clot burden) and the compromise to the patient. Small, nonobstructive thrombi are often managed with an increase in anticoagulation, close monitoring, and reevaluation. Thrombolytic therapy and/or operative exploration (thrombectomy or valve replacement) are required for larger thrombi resulting in hemodynamic compromise. Results of thrombolytic therapy in children mirror those in adults with an approximate 75% success rate and 25% incidence of complications including bleeding, thromboembolism, reoperation, and death (244,245,246,247,248,249,250,251,252). Until recently management guidelines for valve thrombosis in children have been taken from the adult experience and the reader is referred to the American College of Cardiology/American Heart Association Guidelines for Management of Patients with Valvular Heart Disease (142) and the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th edition) (239). Reviews and case reports in children and adolescents have been recently published (244,247,253). Arrhythmias Concerns for thrombosis in children with arrhythmias focus on three areas: atrial arrhythmias especially intra-atrial reentrant tachycardia/atrial flutter, pacemakers/internal cardiac defibrillators, and electrophysiologic studies/catheter ablation procedures. In addition, the novel anticoagulants, dabigatran (direct thrombin inhibitor), rivaroxaban (factor Xa inhibitor) and apixaban (factor Xa inhibitor) have recently been approved for use in nonvalvular atrial fibrillation in adults only. The advantage of the novel anticoagulants is that routine laboratory monitoring is not required. The disadvantage is that there currently are not specific antidotes for major bleeding complications in children. An extensive literature exists regarding arrhythmia and pacemaker-related thrombosis in both adults and children and is beyond the scope of this chapter. Acquired Heart Disease The two acquired heart diseases with known increased thrombotic risk are coronary involvement associated with Kawasaki disease and cardiomyopathy/myocarditis. Kawasaki Disease During the inflammatory phase of Kawasaki disease, two processes increase the risk of thrombus formation: vasculitis-induced endothelial injury to the coronary arteries and an increase in platelet quantity and activation. Later in the course, if coronary aneurysms form, especially giant coronary aneurysms of 8 mm or greater, there is an increased risk of thrombus formation within the aneurysms secondary to low coronary blood flow velocities and relative stasis in addition to the endothelial injury and activated platelets. An extensive literature exists on the pathogenesis and natural history of Kawasaki disease and the diagnosis and management of thrombotic complications and is beyond the scope of this chapter (115,116,117,118,119,120,121,122,123,124,125) (see Chapter 58, Kawasaki disease). Recommendations for thrombosis prevention are outlined in the American Heart Association 2004 scientific statement, “Diagnosis, Treatment, and Long-term Management of Kawasaki disease: a Statement for Health Professionals from the Committee on Rheumatic Fever, Endocarditis and Kawasaki Disease, Council on Cardiovascular Disease in the Young, American Heart Association” (115). The reader is also directed to the 2012 American College of Chest Physicians Evidence-Based Clinical Practice Guidelines, Antithrombotic Therapy in Infants and Children (194) and recent reviews and guidelines from England, Canada, and Japan (117,118,119,120,122,123,125). Cardiomyopathy/Myocarditis Children and adolescents with cardiomyopathy including myocarditis are at risk for intracavitary thrombus formation secondary to stasis, regional wall motion abnormalities, endothelial dysfunction, and/or arrhythmias. Prevalence has been reported from 14% to 16% in moderate-sized pediatric series and thrombi have been identified in patients despite systemic prophylactic anticoagulation (137,138,139,140,141,257,258,259,260,261,262). Data are limited from which to generate management guidelines regarding thrombosis prophylaxis, diagnosis, and treatment in the pediatric population. Limited guidelines are outlined in the 2012 American College of Chest Physicians Evidence-Based Clinical Practice Guidelines, Antithrombotic Therapy in Infants and Children (194) and in the 2013 American Heart Association Scientific Statement Prevention and Treatment of Thrombosis in Pediatric and Congenital Heart Disease (168). Cardiac Catheterization The risk for thrombotic complications associated with cardiac catheterization is a known concern in pediatric cardiology that has generated a substantial literature and is beyond the scope of this chapter (126,127,128,129,130,131,133,134,135,136,137) (see Chapters 16 and 17). The areas of major interest are thromboprophylaxis during diagnostic and interventional cardiac catheterization, postprocedure prophylaxis for intravascularly placed stents and occlusion devices, and management of catheterization-related vascular thrombosis. Guidelines for primary prevention and treatment of thrombi related to diagnostic and interventional cardiac catheterization are outlined in the 2013 American Heart Association Scientific Statement Prevention and Treatment of Thrombosis in Pediatric and Congenital Heart Disease (168) and to a lesser extent in the 2012 American College of Chest Physicians Evidence-Based Clinical Practice Guidelines, Antithrombotic Therapy in Infants and Children (194). Bridging Therapy The question frequently arises concerning the discontinuation of anticoagulation in the event of an upcoming invasive procedure (operation, dental work, catheterization). Two factors should be considered: (a) the risk of thrombosis during cessation of anticoagulation and (b) the potential of bleeding during the procedure (i. Guidelines for the management of warfarin during invasive procedures in adults with prosthetic valves are well established (142,263,264). Guidelines for the management of anticoagulation during invasive procedures in children with prosthetic valves as well as those anticoagulated for other reasons and with other agents (i. The options are as follows: Perform the procedure without interruption in anticoagulation. Restart heparin after the operation as soon as the risk of bleeding is determined to be low. Thrombolytic Therapy in Children and Adolescents with Heart Disease Local and systemic thrombolytic therapy has been used extensively in adults (252,266,267), as well as in children and adolescents with heart disease and thrombotic complications and in addition in children with catheter-related intracardiac thrombi and intracardiac masses secondary to infective endocarditis. The strongest indication for thrombolytic therapy includes either a life- or limb-threatening thrombotic event. Significant bleeding (including intracranial hemorrhage) and thromboembolism are known complications of thrombolysis. The highest risk of bleeding from thrombolytic therapy is seen in preterm infants. When possible, the expertise of a pediatric hematologist (hematology consultation) should be sought. Contraindications to thrombolytic therapy generally include active bleeding, an inability to maintain the platelet count >75,000/ μL or fibrinogen >100 mg/dL, a major operation or site of hemorrhage within 7 to 10 days, seizures within 48 hours, central nervous system surgery/ischemia/trauma/hemorrhage within 30 days, preterm infant <32 weeks, or uncontrolled hypertension. These contraindications are not absolute and the relative risks of thrombolytic therapy should be weighed against the potential benefits in each clinical situation. An increase in the D-dimer and a drop in the fibrinogen level are indicative of a “lytic” state. To minimize the risk of bleeding, if the fibrinogen level drops below 100 mg/dL, consider either holding thrombolytic therapy or infusing cryoprecipitate as an external source of fibrinogen.
It is through this fssure that tumors can extend from the infratemporal fossa and pterygopalatine fossa up toward the orbital apex generic levitra plus 400mg fast delivery erectile dysfunction juicing. Additionally buy levitra plus 400mg otc erectile dysfunction 38 years old, tumors may follow the infraorbital nerve and maxillary nerve to enter Endoscopic Anatomy the pterygopalatine fossa and move posteriorly toward the cavernous sinus and carotid artery buy levitra plus 400mg cheap erectile dysfunction cancer. Endoscopic Anatomy of the Greater Palatine Canal As the orbital apex and sphenoid is approached, the inferior and the Pterygopalatine Fossa portion of the lamina papyracea thickens. The lateral wall of the fssure is formed by the medial wall of the middle cranial The greater palatine canal and the pterygopalatine fossa fossa. The pterygopala- infraorbital fssure and it is around this structure that tumor tine fossa is similar to an inverted cone and the bottom can insinuate to reach the orbital apex and then expand into 208 Endoscopic Sinus Surgery D Fig. The vidian canal can be seen entering the white line and the sphenopalatine foramina are indicated with the white ar- posterior wall of the pterygopalatine fossa (black arrow). The posterior wall of the maxillary sinus has the infraorbital fissure are continuous with each other. Signifcant expansion can occur so that the tumor may reach the cavernous sinus and even the carotid artery. To understand how the medial aspect of the infra- orbital fssure can be surgically accessed, Figs. Note how the medial part of the fssure communicates with the pterygopalatine fossa whereas the lateral part of the fssure communicates with the orbit. Note the landmarks of the lateral wall including the optic nerve, the anterior genu of the intracavernous carotid artery, the maxillary impression for the maxillary division of the trigeminal nerve, and the vidian nerve in the foor of the sphenoid sinus. The blue silicone shows the anterior genu of the intracavernous carotid is completely within the cavernous sinus. The anterior limit of this marks the beginning of the orbital apex, the supraorbital fssure. The occulomotor, trochlea, and ophthalmic division of the tri- geminal nerve can be seen in Fig. In this image the periorbita of the orbital apex has been retracted with a Freer dissector. Analysis of the maxillary nerve can clearly show the path which tumors in this region may take. Head- ing posteriorly they may enter the cavernous sinus and in- vade the intracavernous structures such as the intracavern- ous carotid artery. This depression corresponds to pneumatization of To access the region of the middle cranial fossa and fora- the optic strut (the bony bridge that separates the optic canal from men ovale, further removal of the lateral wall of the sphe- the superior orbital fssure). To achieve this both the vidian may result in a pneumatized anterior clinoid process which will place nerve in the foor of the sphenoid sinus and the maxillary the optic nerve on a mesentery. The bone has been removed and the anterior genu of following removal of the lateral sphenoid wall. This allows anteriorly to the pterygopalatine fossa inferiorly and the orbital apex su- clear visualization of the nerves within the dural layers of the lateral periorly. Note the periorbita the foramen rotundum from the superior orbital fssure/orbital apex. This relationship is important as it helps one to un- the right maxillary nerve and the infraorbital fssure and the pterygopala- derstand how tumors spread from one fossa to another and on occasions tine fossa as viewed from an anterosuperior aspect. Although dura covers the cavernous sinus as it is approached from the sphenoid sinus, this covering is very thin and tenuous with multiple small veins joining or leaving the cavernous sinus so that such a dissection can be quite bloody and the bleeding difcult to control. Endoscopic Anatomy of the Infratemporal Fossa Once the bone overlying the posterior wall of the maxil- lary sinus has been removed, the pterygopalatine fossa and infratemporal fossa are seen (Fig. These fossae are covered by periosteum and the contents are exposed by removing the periosteum. Once the fat has been removed the underlying Bone has been removed at the lateral recess (between the vidian nerve and maxillary artery and muscles of the infratemporal fossa can the maxillary division of the trigeminal nerve). The vidian canal leads directly to the second genu of the internal carotid artery as it turns vertically and runs up the lateral wall of the sphenoid toward the pituitary fossa. This bone removal exposes the space between the middle cranial fossa plate and the lat- eral wall of the sphenoid both below and above the maxil- lary nerve. As the bone removal continues posteriorly the foramen ovale and the mandibular branch of the trigeminal nerve are seen which are lateral and anterior to the carotid artery (Fig. The vidian nerve is medial and marks the position of the carotid at the junction of the foor and poste- rior wall of the sphenoid. The space above the maxillary nerve is just below the orbital apex, and tumors expanding into this region will cause compression of the or- bital apex. The relationship of the orbital apex, lateral wall of sphenoid, and medial wall of the middle cranial fossa is demonstrated in Figs. If the remaining bone of the lateral wall of the sphe- heads of the lateral pterygoid muscle can be seen, where they attach and cover the superfcial surface of the lateral pterygoid plates. The endoscope can be placed into the max- illary antrostomy while the dissecting instrument is placed through the canine fossa puncture. This can be reversed with the endoscope being placed through the canine fossa puncture and instrument through the maxillary antrostomy. The only area where access may not be adequate is the anterior face of the maxillary sinus. The maxillary artery enters the in- fratemporal fossa between the superior and inferior head of the lateral pterygoid muscles. Sinus Tumors (Videos 44 and 45) If a tumor cannot be accessed with the canine fossa trephi- nation or it originates from a large area or from the anterior wall of the maxillary sinus, endoscopic medial maxillec- the greater palatine canal with the maxillary artery enter- tomy should be performed. If additional access is required, ing the infratemporal fossa between the two heads of the the frontal process of the maxilla can be drilled away. Removing angulation to the anterior wall as described previously the temporalis muscle reveals the ramus of the mandible in this chapter. With the use of an angled endoscope look- able to be accessed and the tumor and underlying mucosa ing inferiorly the superfcial head of the medial pterygoid should be removed. Resection of the medial maxilla removed a large Tumors Involving the Maxillary part of the tumor origin. In addition the tumor took origin Sinus, Pterygopalatine, and from the adjacent foor and posterior wall of the maxil- Infratemporal Fossae lary sinus. The bone in the region of origin of Antrochoanal Polyp the tumor was able to be drilled with a diamond burr to en- sure no tumor had infltrated into bony crevices seen in the Antrochoanal polyps commonly form from the posterior region of new bone formation classically associated with wall of the maxillary sinus. The frst step The following patient presented with an inverting papilloma is to perform a large middle meatal antrostomy and to ex- that took origin around a region of new bone formation on the pose the site of origin of the tumor. This anterior and easily accessed through the middle meatal antrostomy then lateral area was able to be accessed (after an endoscopic medial the tumor and the site of origin are resected with a margin maxillectomy) with a 70-degree diamond burr and the origin of normal mucosa around the attachment. If the site of origin of the tumor completely cleared with drilling of the underlying 214 Endoscopic Sinus Surgery Fig. It is common for inverting papilloma to removal of inverting papillomas are better than those achieved originate from a region of new bone formation and therefore in the past using an open approach. The fgures of recurrence it is important to drill away this new bone as mucosa may in- rates of inverting papilloma with open procedures average vaginate into the bony crevices associated with new bone and 18% whereas those performed endoscopically average 12%.
Anatomic relationship between the internal jugular vein and the carotid artery in preschool children—an ultrasonographic study levitra plus 400mg on line erectile dysfunction pump walgreens. Transhepatic therapeutic cardiac catheterization: a new option for the pediatric interventionalist order levitra plus 400 mg online erectile dysfunction treatment nasal spray. Transhepatic vascular access for diagnostic and interventional procedures: techniques purchase generic levitra plus on line erectile dysfunction treatment natural food, outcome, and complications. Feasibility of pulmonary artery pressure measurements in infants through aorto-pulmonary shunts using a micromanometer pressure wire. Assessment of pulmonary hypertension in the pediatric catheterization laboratory: current insights from the Magic registry. Hydraulic formula for calculation of the area of the stenotic mitral valve, other cardiac valves, and central circulatory shunts. Diagnostic reference levels and effective dose in paediatric cardiac catheterization. Visualization of the pulmonary arteries in pseudotruncus by pulmonary vein wedge angiography. Enlarged bronchial arteries after early repair of transposition of the great arteries. Adverse event rates in congenital cardiac catheterization - a multi-center experience. Hazards of cardiac catheterization in children with primary pulmonary vascular obstruction. The use of heparinization to prevent arterial thrombosis after percutaneous cardiac catheterization in children. Fibrinolytic therapy for femoral arterial thrombosis after cardiac catheterization in infants and children. Cheatham Introduction Catheter-based techniques, whether palliative or corrective, are the accepted therapy for many congenital cardiac defects. Interventional, or, better termed, therapeutic catheterizations, were initiated by Dotter and Judkins, who first reported the treatment of peripheral vascular lesions during a catheterization in 1964 (1), when they dilated a stenotic peripheral vessel through a cutdown on the vessel. The next major innovative accomplishment and the first intracardiac therapeutic catheterization procedure for pediatric congenital heart disease were the balloon atrial septostomy done by Rashkind and Miller in 1966 (2). That procedure really “set the stage” for all therapeutic catheterization procedures used today. In 1967, Porstmann and colleagues reported the first nonsurgical corrective procedure in the catheterization laboratory with their description of a technique for closure of a patent ductus (3). Even though their device has not found widespread use, it set the stage for future development of transcatheter devices. One of the largest contributions to interventional cardiology has probably been made by Gruentzig, a Swiss-native who in 1976 reported on dilation of peripheral vessels with noncompliant balloons. This initiated a rapid innovative spurt within the congenital cardiac community during which narrowed lesions at various locations were treated with balloon angioplasty, frequently initially in a noncontrolled fashion. Jean Kan reported the first successful transcatheter static balloon pulmonary valvuloplasty (6) and Dr. Charles Mullins introduced endovascular stents into the management of patients with congenital cardiac lesions (8), and the long list of innovations reached another milestone when Dr. Phillip Bonhoeffer, a German cardiologist working in France in 2000, performed the first transcatheter pulmonary valve replacement in a human (9). Transcatheter valve therapies and other interventional therapies to treat patients with structural heart disease have rapidly increased over the last few years. These therapies are not limited anymore to patients with congenital heart disease. In this section, the most important therapeutic catheterization procedures performed as of this writing are discussed. This chapter is not intended as a complete and exhaustive textbook of interventional techniques, but instead should give the reader a general overview of therapeutic catheterization. Acknowledgment We have used and expanded upon this chapter published in other editions of this textbook and therefore acknowledge the previous contributions made by Drs. It should be emphasized that not every pediatric cardiologist, or, for that matter, every center, should offer every therapeutic catheterization procedure. For any procedures to be performed at any particular institution, minimal specific skills are required, special techniques must be mastered and maintained, and a large inventory of specialized and expensive catheters and devices must be stocked to offer the patient an optimal procedure. Absence of appropriate qualifications and equipment can result in unnecessary risk to the patient without a reasonable chance of the therapeutic catheterization procedure being successfully accomplished. In fact, even if the patient is not acutely harmed by the attempt, it is important to be aware of the fact that the next procedure in a more appropriate setting might be compromised by a previously unsuccessful attempt. Adverse Events and Quality Improvement For many years, reporting of procedure-related adverse events was limited mostly to single-center retrospective experiences, often without any clearly and consistently applied criteria of what would be considered an adverse event, and how its severity should be defined (11,12,13). The data derived from these registries often provided the only prospective multicenter outcome data for many procedure types. This registry documented not insignificant rates of adverse events, 10% for diagnostic cases, and 20% for interventional procedures. Higher severity (level 3 to 5) adverse events occurred in 9% of interventional cases, and 5% of diagnostic cases. The incidence of life-threatening adverse events has been reported to be as high as 2. However, to accurately compare adverse event rates and outcome between institutions and operators, an adjustment for case mix and hemodynamic vulnerability is required. Following the definition of procedure-type risk groups, Bergersen and colleagues reported on hemodynamic variables associated P. The Interventional Armamentarium General Considerations The spectrum of transcatheter procedures available for the treatment of children and adults with congenital heart disease has rapidly increased over the last three decades. With rapid progress that is being made in the development of new and more refined equipment, the operator has an inherent responsibility to keep up-to-date with these development efforts and to avoid procedural failures in situations where the use of a different type of equipment may lead to a very different outcome. Even though many interventional meetings have a focus on new device developments, the choice of appropriate balloons, catheters, sheaths and wires is in many situations even more important for a successful outcome. It is beyond the scope of this discussion to describe all available balloon catheters, but the operator has to make a well- informed decision on which balloon to use, based on profile, rated maximum pressure, available lengths, and degree of compliance and adjust his/her choice to suit specifically the therapeutic intervention that is intended. Even though transcatheter devices have long been available for the management of congenital cardiac lesions, the greatest progress has been made through introduction of a large variety of newer devices that were specifically developed for individual congenital cardiac lesions over the last 10 years. This progress has enabled many procedures to be safely performed in a much wider range of clinical centers. In this chapter, a variety of device-specific sections have been taken with permission from an article on this topic that was published in “Expert Review of Medical Devices” (29). The spectrum of devices that are discussed below is not intended to be complete, but rather represents subjective choices of the authors. Devices for the treatment of structural cardiac lesions or the treatment of acquired heart disease are not included in this chapter.
Specific associations can provide clues to pathogenesis and strengthen the case for causality levitra plus 400 mg cheap erectile dysfunction caused by neuropathy. The relatively specific association of retinoic acid exposure to complex conotruncal defects not only helped identify it as a cardiac teratogen but pointed toward a developmental effect on neural crest cells discount levitra plus generic erectile dysfunction treatment jaipur. However levitra plus 400mg low price erectile dysfunction kits, specificity is not and need not be always present: established teratogens such as maternal diabetes can cause a variety of heart defects. Identifying specific associations requires careful study design in order to collect an unbiased sample of specific phenotypes, and the input of expert clinicians in case of review and classification. Finally, information on specificity is useful when assessing the potential benefits for prevention—a risk factor for hypoplastic left heart syndrome would be viewed differently from one causing a small atrial septal defect. Magnitude of risk can be estimated in case-control and cohort studies, in the form of relative risk of disease, that is, the ratio of disease risk in the exposed divided by the risk in the unexposed. Ideally, one would also estimate the absolute risk for congenital heart defects, that is, the absolute rate of disease in those exposed (the numerator of relative risk). In reviews, publication bias needs to be considered Specificity: Establishing specificity requires typically large samples of well-characterized cases of What type(s) specific types of heart defects: This requires large collaborative studies (for sample of heart size) and clinician involvement (for accurate case classification) defects does the factor cause? Risks may combine on different scales (additive, multiplicative, or exposed to other). Characterizing interactions typically requires larger, very well-designed more than one studies. Population Population attributable risk depends on both the magnitude of risk (relative risk) and attributable the fraction of population that is exposed (exposure frequency). The latter can be fraction: What inferred from population-based surveys targeting the at-risk population (e. Computing an attributable fraction is easy, but its value in a population depends on how the quality of the inputs and how well the assumptions are met is attributable (causality) to the factor? Interactions can be important for prevention and risk assessment, but are typically difficult to identify conclusively and characterize precisely. An interaction occurs when the concurrent presence of two factors (genetic or environmental) changes the association between each factor alone and disease. For example, a scenario may occur (not as implausibly as may appear) in which a diabetic woman takes lithium and a folic acid supplement. The question then becomes whether and to what extent these individual risks cumulate, and if they do, on which scale (additive, multiplicative, or other). The question is not academic: Finding that a vitamin supplement mitigates the risk associated with diabetes or lithium can translate into an additional tool for prevention. Interactions can provide clues to shared pathogenesis and help discover new causes and mechanisms of congenital heart defects. However, studying interactions requires stringent precision in assigning exposure and usually much larger sample sizes compared to studies looking at the main effects of risk factors. Attributable fraction depends not only on the relative risk but also on the fraction of population that is exposed. It is intuitive that the more women exposed to a teratogen in a population and the higher the teratogenic risk, the higher the number of affected pregnancies. It is defined as the proportion of cases in a population that can be attributed to a given exposure and is computed as a nonlinear function of disease risk and exposure prevalence, using one of several formulas (122,123). First, the attributable fraction increases as a nonlinear function of the relative risk—the higher the relative risk, the steeper the increase. Second, the higher the frequency of exposure to a risk factor, the higher the fraction of cases in the population that is attributable to that factor. Because of this joint effect of relative risk and exposure frequency, even weak risk factors, with odds ratios of 1. High exposure frequencies are not unrealistic: Lack of folic acid supplementation in different countries easily exceeds 50% and is probably close to 100% in some, and smoking rates of 15% or more in women are not uncommon in some countries or groups in the population. Crude estimates of attributable fraction can be computed easily, but in many practical settings is has subtleties that must be appreciated lest the estimates be biased (122). Such settings include using relative risk estimates derived from multivariable (adjusted) analyses, a common situation in modern epidemiologic studies, or when the exposure has more than two levels rather than being categorized simply as present or absent (124,125). With rare exceptions (126), a systematic assessment of population attributable risk for heart defects has been uncommon. Because of its potential implications for prevention, new rigorous evaluations would be very helpful. Candidates for Prevention: Review of Selected Risk Factors Because of the focus on primary prevention, this review will center on selected modifiable risk factors (Table 2. The list and the summary of data are necessarily selective, and focus on the elements just discussed that are relevant to primary prevention, such as the strength of the evidence, the specific outcomes related to the factor, the preventability of the risk factor, and its frequency in the population. Additional data can be found in several reviews (1,3,4,120) as well as in the cited primary sources. Scientific knowledge is in a continuous state of flux, so these summaries are inherently provisional. Generally is associated with conotruncal For influenza, associated with high fever. Exposure is a probably not concern because many users are young women Lithium Ebstein Relative risk Use probably Risk lower than anomaly, likely <10, infrequent but originally thought, but others between 1. Diabetes Maternal pregestational diabetes is an established, serious risk factor for congenital heart defects, and a clear priority target for prevention efforts (131). It increases the risk for many types of heart defects, not uncommonly as part of multiple congenital anomaly patterns, (15,30,131,132,133,134,135,136,137,138,139). Cardiac phenotypes consistently associated with maternal diabetes include laterality defects (heterotaxy) and several conotruncal defects, and to a lesser extent also left ventricular outflow obstructive defects, atrioventricular septal defects, total anomalous pulmonary venous return, and septal defects (15,30,131,132,133,134,135,136,139,140). Estimated relative risks for heart defects in the aggregate range approximately from 3 to 6, though they can be higher for some types of heart defects, especially when associated with extra-cardiac anomalies (15,131,132,133,135,136,138,139). Separate risk estimates associated with type 1 and type 2 diabetes are rarely available. Some studies have suggested an excess risk also with gestational diabetes, but the literature is inconsistent (134,141,142,143). The frequency of diabetes among women of childbearing age varies by country, age, and other factors. Rates of diabetes are also rising in many countries, including developing countries (144,145). Data suggest many women could have unrecognized diabetes—one study estimates that in the United States, for every two women of childbearing age diagnosed with diabetes, there is another one with undiagnosed diabetes (146). Careful metabolic control before conception can reduce considerably the teratogenic risk associated with maternal diabetes (111,147,148). Preconceptional diabetes management could decrease the risk for pregnancy loss and congenital malformation for approximately 113,000 births per year (111). Estimates of the population attributable fraction specifically for congenital heart defects have been attempted for the United States (131). In practice, however, many affected pregnancies continue to occur (111,138,149), highlighting the challenges of implementing optimal preconceptional control (150). Some findings suggest that birth defect risk may be lower among diabetic women who also took a folic acid–containing multivitamin supplement from before conception (133). If confirmed, taking such a supplement could represent an adjunct prevention strategy for diabetes- associated birth defects.
All Coronary Arteries from Pulmonary Artery Rarely both right and left coronary arteries 400 mg levitra plus for sale impotence viriesiem, or a single coronary artery generic levitra plus 400 mg free shipping erectile dysfunction pills names, come from the pulmonary trunk purchase levitra plus overnight delivery erectile dysfunction at 18. Unless there is a cardiac lesion causing pulmonary hypertension, these children do not survive infancy without surgical intervention. More recently, these rare patients who have had dual coronary surgical reimplantation have survived (51). While one occurred in an infant who succumbed to a myocardial infarction, the others were in adults who presented predominantly with angina. Precordial murmurs were common, most had electrocardiographic evidence of ischemia. Angiography was diagnostic, and surgical treatment by ligation of the anomalous artery or connecting it to the aorta has been recommended (18). Left Circumflex Coronary Artery from the Pulmonary Artery or Branches A few of these anomalies have been reported (18), and in many patients the circumflex coronary artery was attached to a branch pulmonary artery rather than to the main pulmonary trunk. Right Coronary Artery from the Pulmonary Artery This anomaly is rare, only about one-tenth as common as the left main coronary artery coming from the pulmonary artery (17,31,33). The anomaly was initially known only as an incidental finding at autopsy (18), but recently it has been associated with ischemia, syncope, cardiomyopathy, and sudden death (52,53). Echocardiography with Doppler examination or cineangiography demonstrates the abnormal attachment of the right coronary artery to the pulmonary trunk and the retrograde flow from the right coronary artery to pulmonary artery. If echocardiography is nondiagnostic, definitive imaging of the anomalous right coronary artery origin can be obtained by computed tomography scan (28), or from angiography using the left coronary artery to fill the right by collaterals. Treatment Because most patients are asymptomatic and remain so, there is no way to determine which patients are at risk of dying without surgical correction of this defect. Nevertheless, because sudden death is a risk, many cardiologists recommend surgical correction, which has been done by reimplanting the right coronary artery into the aortic root (52). Miscellaneous Anomalies: Myocardial Bridges The large epicardial coronary arteries run on the surface of the heart, with only their terminal branches penetrating the muscle, but it is very common for part of the epicardial artery to dip beneath the epicardial muscle for several millimeters so that there is a muscle bridge over the large artery (54). Most of these bridges are not functionally important, particularly if they are superficial. There are, however, documented examples of myocardial ischemia (55) or infarction associated with these bridges, including relief of ischemia after myotomy. During coronary angiography, a portion of the coronary artery appears to be narrowed in systole but widely patent in diastole, distinguishing it from a partially occlusive lesion of the artery (54). Because myocardial bridges are so common and do not necessarily indicate present or future coronary arterial disease, the decision about myotomy to relieve anginal symptoms must be made carefully. Not only should there be a well-defined muscle bridge, but there should be ischemia, based on electrocardiography or documented on nuclear scan or stress echocardiography, in the region supplied by the artery with the bridge. Ischemia may be due to long, thick bridges that compress the artery and relax unusually slowly so that diastolic filling of the coronary artery beyond the bridge is impaired. Under these circumstances, disappearance of symptoms and of signs of ischemia may follow myotomy (55). Although myocardial bridges causing ischemia are rare in children with normal hearts, they may represent a significant cause of morbidity and mortality in children with hypertrophic cardiomyopathy (56), although this is also debated. Myocardial bridges with hypertrophic cardiomyopathy have been associated with chest pain, exercise intolerance, ventricular arrhythmias, and cardiac arrest in some, but debated in other studies (5,57). Unroofing the myocardial bridge has been reported to reduce the incidence of sudden death and arrhythmias in these patients (56). Children with hypertrophic cardiomyopathy and the above symptoms should be evaluated for bridges by stress perfusion imaging and selective coronary arteriography, and consideration should be given for unroofing the bridges if detected and felt to be causative. Coronary Artery Patterns with Congenital Heart Defects Complete Transposition of the Great Arteries Anomalies of the coronary arteries in transposition of the great arteries are important to identify because some patterns have been more difficult to transfer with the arterial switch operation. Anomalies occur in both the origin and distribution, with further anomalies secondary to intramural coursing of some vessels. The terminology of the anomalies has been controversial because the aorta and main pulmonary artery are abnormally related in complete transposition of the great arteries, and the aortic sinuses do not have their normal positions. The nomenclature of the facing sinuses depends on the relationship of the great vessels. If the vessels are side by side, then the sinuses are termed anterior or posterior. If the great vessels are oblique, the sinuses are left anterior or right posterior. The presence of a ventricular septal defect or of side-by-side great vessels should alert the cardiologist to an increased likelihood of coronary anomalies. In almost all patients, the coronary arteries arise from the facing sinuses (58,59). In 60%, the coronary arteries come from their appropriate sinuses and branch normally, a pattern seen most often with the aorta anterior and to the right of the pulmonary artery. The coronary arteries usually take the shortest course to reach their distribution, and because the aorta is anterior, the left main and circumflex coronary arteries pass anterior and leftward to the right ventricular outflow tract (Fig. The next most common variation is the left circumflex arising from the right coronary artery and coursing posterior to the pulmonary artery, which is seen in about 20% of patients, usually with side-by-side great vessels (Fig. The coronary arteries also may be completely inverted, with the right coronary artery arising from a left anterior sinus and the left coronary artery arising from the right posterior sinus (Fig 32. The coronary vessels also may be partially inverted, with the left circumflex arising from the right posterior sinus and the left anterior P. Variants with single (8%) and intramural (5%) coronary arteries are not illustrated. Finally, various single coronary anomalies may occur, and intramural coursing of any of the variants may occur, usually with branches passing between the great vessels. These variations affect the planning and conduct of the arterial switch operation because they may make it difficult to move the coronary arterial origins to the neoaortic root without excessive tension. Tetralogy of Fallot About 40% of patients have an abnormally long, large conus artery that supplies a significant mass of myocardium. In 4% to 5%, the left anterior descending coronary artery arises from the right coronary artery and passes across the right ventricular outflow tract (see Fig. Occasionally, a single coronary artery comes from either the right or left sinus, and the major branch that crosses the heart may pass across the right ventricular outflow tract (see Fig. If major arteries cross the right ventricular outflow tract, it makes surgery with the traditional transannular incision more difficult. To avoid cutting the artery and infarcting part of the myocardium supplied by it (61), the surgeon may make incisions parallel to the artery, make incisions above and below the artery, tunnel underneath the artery, or bypass the stenotic region with a conduit (60). All these approaches interfere with the effectiveness of the surgery and in the small infant may lead to the decision to palliate rather than perform a total repair. These anomalies may be detected by echocardiography, and if the anatomy is uncertain, then aortic root angiography or selective coronary angiography is needed (60). Although the surgeon can usually see the anomalies, there are advantages in knowing about them in advance to plan the procedure more effectively. Furthermore, the anomalous arteries may not be visible if they are obscured by epicardial adhesions from previous surgery or if they run deep in the myocardium.
Libraries purchase levitra plus 400mg free shipping erectile dysfunction ring, such as those described in this chapter trusted 400mg levitra plus erectile dysfunction questionnaire uk, will continue to play an important role in gene identiﬁcation and functional assignment order levitra plus with american express erectile dysfunction drugs muse. Several commercial and non-proﬁt organizations provide access to all, or most, of the genes present within some fully sequenced genomes (Table 5. In Chapter 3 we looked at ways in which recombinant clones themselves could be selected for, e. However, identifying the individual sequence or function of the recombinant portion of the clone is more difﬁcult altogether. What is required is some sort of selection process by which one molecule can be distinguished from another. Nevertheless, hybridization screening provided the backbone of gene identiﬁcation for many years. A sheet of nitrocellulose (or nylon) membrane is placed on top of an agar plate to generate a replica of the bacterial colonies. The binding of these sequences to the membrane can be analysed by exposure of the washed membrane to X-ray ﬁlm 6. The colonies to be screened are grown on agar plates that contain the appropriate antibiotics etc. When the bacterial colonies have grown, a sheet of nylon is placed on top of them and then lifted off to produce a replica version of the plate. A portion of each bacterial colony will adhere to the ﬁlter sheet and will be removed from the agar plate along with the nitrocellulose. Typically, the following steps are carried out: • thenylonsheetistreatedwithalkali(e. The probe can be any single-stranded nucleic acid sequence and does not need to match the target sequence precisely. Plasmin is a potent serine proteinase that has important functions in diverse physiological processes in mammals, such as degradation of extracellular matrix proteins, blood clot dis- solution, cellular migration and cancer metastasis (Vassalli and Saurat, 1996). In mammalian plasma, plasmin degrades blood clot networks to produce sol- uble products. Plasmin is produced from a precursor, plasminogen, through limited proteolysis by plasminogen activators. Some of the resulting protein fragments were subjected to amino acid sequencing and one of the peptides produced in this way is shown in Figure 6. Of the 15 bases within the ﬁve codons, only four of them con- tained potential alternate sequences. Probe design for the isolation of the human tissue-type plasminogen acti- vator (Pennica et al. This sequence (representing amino acids 253–257 of the 527-amino-acid protein), was generated following digestion of the isolated full-length protein with trypsin. The probe sequence outlined in yellow represents that which is precisely complementary to the isolated gene 6. For example, some of the histone genes encoded by the sea urchin have been used to isolate the homologous histone genes from a frog library (Old et al. A larger number of degeneracies in a probe sequence will result in the binding of the probe to sequences that do not encode the intended target gene, whereas a highly speciﬁc probe will bind to relatively few gene sequences. Consequently, peptide sequences containing the amino acids methionine and tryptophan, which are each encoded by a single triplet, are particularly impor- tant for designing such probes. As we have previously seen with Southern blotting (Chapter 2), the stringency of washing the probe from the membrane can be used to adjust the number of positive interactions that occur. Hybridization probes are usually radioactively labelled to aid their easy detec- tion when bound to the membrane. Colony screening, as described above, can be used to screen plasmid or cosmid based libraries. However, with only slight modiﬁcations it can also be used to screen λ phage libraries (Benton and Davis, 1977). This results in a ‘cleaner’ background (less background probe hybridization) for λ plaque screening. Screening in this way, however, means it is unlikely that a single pure recombinant clone will be isolated from one round of screening. In this case, an area of agar corresponding to the site of the spot on the original agar plate was removed and the multiple plaques contained within it were re-plated at a lower density. The screen was then repeated to generate a secondary hybridization pattern that was enriched for the plaque showing as positive in the screen. Two or three rounds of screening are often required before a pure plaque can be isolated. In a hybridization screen of a λ phage library, positives from the ﬁrst round of, high-density, screening are re-plated and re-screened at lower density. Degenerate primers can be used to amplify portions of homologous genes from the library (Takumi, 1997). Even if the protein is not fully functional, the sequence of the expressed peptide is likely to be unique within the host cell. Therefore, mechanisms to identify these unique polypeptide sequences can be used to screen the library in order to identify particular clones. Antibodies are relatively straightforward to produce if a puriﬁed, or even partially puriﬁed, protein is available. The gene encoding this protein can then be identiﬁed using the antibody in screening procedures outlined below. Screening of this type does not rely upon any particular function of the expressed foreign protein, but does require a speciﬁc antibody to that protein to be available. Antibodies are raised when a foreign protein or peptide is injected into an animal. Often, the animal used to raise antibodies for use in the laboratory is the rabbit or mouse, but sheep, goats, pigs and horses have all been used to generate larger amount of antibody (Harlow and Lane, 1999). The presence of the foreign protein (antigen) is detected in the animal by surface receptors on B and T lymphocyte cells. Each B cell has many thousands of different receptors on its surface that are able to bind to particular antigens. The binding of the antigen to an individual receptor results, via a complex pathway, in the descendants of that B cell secreting vast numbers of the soluble form of that particular receptor. Antibodies are glycoproteins composed of subunits containing two identical light chains (L chains), each containing about 200 amino acids, and two iden- tical heavy chains (H chains), containing about 400 amino acids each (Davies, Padlan and Sheriff, 1990). The amino-terminal 100 or so amino acids of both the H and L chains vary greatly from antibody to antibody – these are termed the variable (V) regions. The amino acid sequence variability in the V regions is especially pronounced at three hypervariable sites (Figure 6. The ﬁve classes of antibodies (Harlow and Lane, 1999) Class H chain L chain Subunit structure IgA or λ (H2L2)2 IgD or λ H2L2 IgE or λ H2L2 IgG or λ H2L2 IgM or λ (H2L2)5 L and the H chains together to form an antigen binding site. Only a few different amino acid sequences are found at the carboxy-terminal end of H and L chains – the constant (C) regions.