Richard Porter MA MSc FRCOG

Attacks o porphyria can be precipitated by certain drugs (usually those metabolized by the P450 system) erectile dysfunction treatment vacuum device intagra 75 mg on-line, hormonal changes erectile dysfunction doctor philippines buy cheap intagra 100 mg line. Weakness can involve the arms or the legs and can be asymmetric impotence existing at the time of the marriage 50 mg intagra order mastercard, proximal erectile dysfunction medicine online intagra 100 mg purchase free shipping, or distal in distribution treatment erectile dysfunction faqs discount intagra 25 mg free shipping, as well as a ecting the ace and bulbar musculature. Some patients are hyponatremic due to inappropriate secretion o antidiuretic hormone. The urine may appear brownish in color secondary to the high concentration o porphyrin metabolites. I there is no improvement within 24 h, intravenous hematin 2­5 mg/kg per day or 3­14 days should be given. However, the trunk can be involved, and some patients mani est with a mononeuropathy multiplex pattern. The neuropathy is slowly progressive, and eventually weakness develops along with largeber sensory loss. Most patients develop autonomic involvement with postural hypertension, syncope, bowel and bladder incontinence, constipation, impotence, and impaired sweating. Patients generally die rom their systemic illness (renal ailure, cardiac disease). Nerve biopsies reveal axonal degeneration and amyloid deposition in either a globular or di use pattern in ltrating the perineurial, epineurial, and endoneurial connected tissue and in blood vessel walls. The median survival o patients with primary amyloidosis is less than 2 years, with death usually rom progressive congestive heart ailure or renal ailure. Chemotherapy with melphalan, prednisone, and colchicine, to reduce the concentration o monoclonal proteins, and autologous stem cell transplantation may prolong survival, but whether the neuropathy improves is controversial. Nerve biopsy reveals axonal degeneration, endothelial hyperplasia, and, occasionally, perivascular in ammation. Atrophy and weakness o proximal and distal muscles in the a ected leg become apparent within a ew days or weeks. Weakness usually progresses over several weeks or months, but can continue to progress or 18 months or more. Subsequently, there is slow recovery but many are lef with residual weakness, sensory loss, and pain. In contrast to the more typical lumbosacral radiculoplexus neuropathy, some patients develop thoracic radiculopathy or, even less commonly, a cervical polyradiculoneuropathy. Nerve biopsies may demonstrate axonal degeneration along with perivascular in ammation. Patients with severe pain are sometimes treated in the acute period with glucocorticoids, although a randomized controlled trial has yet to be per ormed, and the natural history o this neuropathy is gradual improvement. When severe, a patient may develop sensory loss in the trunk (chest and abdomen), initially in the midline anteriorly and later extending laterally. In regard to cranial mononeuropathies, seventh nerve palsies are relatively common but may have other, nondiabetic etiologies. In diabetics, a third nerve palsy is most common, ollowed by sixth nerve, and, less requently, ourth nerve palsies. Most common is a length-dependent axonal sensorimotor neuropathy characterized mainly by sensory loss in the distal extremities. A pure small- ber neuropathy or a cranial neuropathy, particularly involving the trigeminal nerve, can also be seen. Patients with sensory ganglionopathies develop progressive numbness and tingling o the limbs, trunk, and ace in a non-length-dependent manner such that symptoms can involve the ace or arms more than the legs. Sensory examination demonstrates severe vibratory and proprioceptive loss leading to sensory ataxia. Rarely, a generalized sensory polyneuropathy characterized by pain ul paresthesias and numbness in both the legs and hands can occur. Nonspeci c perivascular in ammation may be present, but only rarely is there necrotizing vasculitis. The most common cranial nerve involved is the seventh nerve, which can be a ected bilaterally. Patients can also present with multiple mononeuropathies or a generalized, slowly progressive, sensory greater than motor polyneuropathy. Nerve biopsy can reveal noncaseating granulomas in ltrating the endoneurium, perineurium, and epineurium along with lymphocytic necrotizing angiitis. Neurosarcoidosis may respond to treatment with glucocorticoids or other immunosuppressive agents. Vasculitic neuropathy can present with a mononeuropathy multiplex, a generalized symmetric pattern o involvement, or a combination o these patterns. Nerve biopsy of en reveals thickening o the epineurial and endoneurial blood vessels as well as perivascular in ammation or vasculitis, with transmural in ammatory cell in ltration and brinoid necrosis o vessel walls. A ected patients typically present with a slowly progressive sensory loss beginning in the eet. Less common are multiple mononeuropathies presumably secondary to necrotizing vasculitis. Immunosuppressive agents are less likely to be e ective in patients with a generalized sensory or sensorimotor polyneuropathy without evidence o vasculitis. A generalized peripheral neuropathy or a mononeuropathy multiplex occurs in 6­14% o patients. A generalized sensorimotor polyneuropathy, pure motor neuropathy, multiple mononeuropathies, autonomic neuropathy, small- ber neuropathy, and neuromyotonia have all been reported in association with celiac disease or antigliadin/antiendomysial antibodies. The pathogenic basis or the neuropathy in these patients is unclear but may be autoimmune in etiology. In patients with vitamin B12 or vitamin E de ciency, replacement therapy may improve or stabilize the neuropathy. Cranial mononeuropathies can also develop, most commonly o the trigeminal nerve, producing numbness and dysesthesias in the ace. Ischemic monomelic neuropathy (see below) can complicate arteriovenous shunts created in the arm or dialysis. Sural nerve biopsies demonstrate a loss o nerve bers (particularly large myelinated nerve bers), active axonal degeneration, and segmental and paranodal demyelination. The sensorimotor polyneuropathy can be stabilized by hemodialysis and improved with success ul renal transplantation. A coexisting encephalopathy may limit the neurologic exam, in particular the sensory examination. Perhaps circulating toxins and metabolic abnormalities associated with sepsis and multiorgan ailure impair axonal transport or mitochondrial unction, leading to axonal degeneration. Clinical mani estations range rom tuberculoid leprosy at one end to lepromatous leprosy at the other end o the spectrum, with borderline leprosy in between. Mononeuropathies, multiple mononeuropathies, or a slowly progressive symmetric sensorimotor polyneuropathy may develop. Nerve biopsy can also be diagnostic, particularly when there are no apparent skin lesions. In contrast, with lepromatous leprosy, large numbers o in ltrating bacilli, H 2 lymphocytes, and organismladen, oamy macrophages with minimal granulomatous in ltration are evident. It is not known i hepatic ailure in isolation can cause peripheral neuropathy, as the majority o patients have liver disease secondary to other disorders, such as alcoholism or viral hepatitis, which can also cause neuropathy. Patients are generally treated with multiple drugs: dapsone, ri ampin, and clo azimine. Other medications that are used include thalidomide, pe oxacin, o oxacin, spar oxacin, minocycline, and clarithromycin. The cellular response is upregulated as evidenced by an increased release o tumor necrosis actor, inter eron, and interleukin 2, with new granuloma ormation. This can result in an exacerbation o the rash and the neuropathy as well as in appearance o new lesions. High-dose glucocorticoids blunt this adverse reaction and may be used prophylactically at treatment onset in high-risk patients. Although early treatment reduces the incidence and severity o some complications. It is characterized by numbness and pain ul paresthesias involving the distal extremities. The neuropathy may be immune mediated, perhaps caused by the release o cytokines rom surrounding in ammatory cells. Neurologic complications may develop during the second and third stages o in ection. In ected individuals present with ulike symptoms o generalized myalgias, headache, atigue, low-grade ever, and irritability within a week to 10 days o the exposure. About 20­70% o patients develop a peripheral neuropathy caused by a toxin released by the bacteria. T ree to 4 weeks af er in ection, patients may note decreased sensation in their throat and begin to develop dysphagia, dysarthria, hoarseness, and blurred vision due to impaired accommodation. A generalized polyneuropathy may mani est 2 or 3 months ollowing the initial in ection, characterized by numbness, paresthesias, and weakness o the arms and legs and occasionally ventilatory ailure. Patients present with severe radicular pain, numbness, and weakness in the legs, which is usually asymmetric. Nerve biopsies can reveal axonal degeneration with necrotizing vasculitis or perivascular in ammation. The most common associated malignancy is lung cancer, but neuropathies also complicate carcinoma o the breast, ovaries, stomach, colon, rectum, and other organs, including the lymphoproli erative system. Patients develop sensory ataxia similar to idiopathic sensory neuronopathy/ganglionopathy. Weakness in muscles innervated by roots corresponding to the dermatomal distribution o skin lesions occurs in 5­30% o patients. Patients usually present with numbness and paresthesias in the distal extremities that are of en asymmetric. Many patients also develop con usion, memory loss, depression, hallucinations or seizures, or cerebellar ataxia. Un ortunately, plasmapheresis, intravenous immunoglobulin, and immunosuppressive agents have not shown bene t. Nerve biopsy may demonstrate endoneurial in ammatory cells in both the in ltrative and the paraneoplastic etiologies. The neuropathy may respond to treatment o the underlying lymphoma or immunomodulating therapies. The neuropathy may improve with treatment o the underlying leukemia or lymphoma or with glucocorticoids. A monoclonal protein, usually composed o or µ heavy chains or light chains, may be identi ed in the serum or urine. Abdominal at pad, rectal, or sural nerve biopsy can be per ormed to look or amyloid deposition. The mechanisms by which these agents cause toxic neuropathies vary, as does the speci c type o neuropathy produced. The risk o developing a toxic neuropathy or more severe neuropathy appears to be greater in patients with a preexisting neuropathy. Chemotherapeutic agents usually cause a sensory greater than motor length-dependent axonal neuropathy or neuronopathy/ganglionopathy. The pattern o involvement may be symmetric, asymmetric, or multi ocal, and the course may be acute, gradually progressive, or relapsing and remitting. In addition, neuropathy can also develop with or without the myopathy leading to sensory loss and distal weakness. These agents contain both hydrophobic and hydrophilic regions that allow them to interact with the anionic phospholipids o cell membranes and organelles. The drug-lipid complexes may be resistant to digestion by lysosomal enzymes, leading to the ormation o autophagic vacuoles lled with myeloid debris that may in turn cause degeneration o nerves and muscle bers. The signs and symptoms o the neuropathy and myopathy are usually reversible ollowing discontinuation o medication. The disruption o the microtubules probably leads to de ective intracellular movement o important proteins, nutrients, and waste products in muscle and nerves. T alidomide is associated with severe teratogenic e ects as well as peripheral neuropathy that can be dose-limiting. Patients develop numbness, pain ul tingling, and burning discom ort in the eet and hands and less commonly muscle weakness and atrophy. Even af er stopping the drug or 4­6 years, as many as 50% patients continue to have signi cant symptoms. Nerve biopsy reveals a loss o large-diameter myelinated bers and axonal degeneration. The neuromyopathy typically appears af er patients have taken the medication or 2­3 years. Nerve biopsy demonstrates a combination o segmental demyelination and axonal loss. Electron microscopy reveals lamellar or dense inclusions in Schwann cells, pericytes, and endothelial cells. The inclusions in muscle and nerve biopsies have persisted as long as 2 years ollowing discontinuation o the medication. Patients usually present with proximal weakness and numbness and tingling in the distal extremities. Loss o dorsal root ganglion cells with subsequent degeneration o both the peripheral and central sensory tracts have been reported in animal models. Nerve biopsy reveals a loss o myelinated bers and giant axons that are lled with 10-nm neuro laments. Hexacarbon exposure leads to covalent cross-linking between axonal neuro laments that result in their aggregation, impaired axonal transport, swelling o the axons, and eventual axonal degeneration.

This is thought to diminish the production of defensins and other antimicrobial peptides erectile dysfunction pills not working buy cheap intagra 100 mg on line, thereby weakening the natural barrier function of the intestinal epithelium and leading to the inflammation characteristic of this disease erectile dysfunction caused by hemorrhoids buy discount intagra 25 mg online. This aggregation of procaspase 1 induces proteolytic cleavage of itself to form the active caspase 1 erectile dysfunction and diabetes type 1 intagra 75 mg sale, which cleaves the immature forms of pro-inflammatory cytokines erectile dysfunction keeping it up intagra 25 mg order on-line, releasing the mature cytokines that are then secreted erectile dysfunction medication otc buy cheap intagra 100 mg on line. The loss of intracellular potassium through efflux can occur during infection with, for example, intracellular bacteria such as Staphylococcus aureus that produce pore-forming toxins. This aggregation seems to trigger the autocleavage of pro-caspase 1, which releases the active caspase 1 fragment from its autoinhibitory domains. For example, Bacillus anthracis expresses an endopeptidase, called anthrax lethal factor, which allows the pathogen to evade the immune system by killing macrophages. The discovery of this pathway was initially confused as being dependent on caspase 1 because of a specific genetic difference between experimental mouse strains. Caspase 11 is encoded by the murine Casp4 gene and is homologous to human caspases 4 and 5. But researchers later discovered that this mouse strain also carried a natural mutation that inactivated the related Casp4 gene. Because the Casp1 and Casp4 genes reside within 2 kilobases of each other on mouse chromosome 9, they failed to segregate independently during subsequent experimental genetic backcrosses to other mouse strains. Thus, mice initially thought to lack only caspase 1 protein in fact lacked both caspase 1 and caspase 11. Gout has been known for many years to cause inflammation in the cartilaginous tissues by the deposition of monosodium urate crystals, but how urate crystals caused inflammation was a mystery. We will also discuss how pathogens can interfere with formation of the inflammasome in Chapter 13. These molecules are bacterial second messengers and are produced by enzymes present in most bacterial genomes. Besides activating effector functions and cytokine production, another outcome of the activation of innate sensing pathways is the induction of co-stimulatory molecules on tissue dendritic cells and macrophages (see Section 1-15). We will describe these in more detail later in the book, but mention them now because they provide an important link between innate Pattern recognition by cells of the innate immune system. These substances are known as adjuvants (see Appendix I, Section A-1), and it was found empirically that the best adjuvants contain microbial components that induce macrophages and tissue dendritic cells to express co-stimulatory molecules and cytokines. As we shall see in Chapters 9 and 11, the cytokines produced in response to infections influence the functional character of the adaptive immune response that develops. In this way the ability of the innate immune system to discriminate among different types of pathogens is used by the organism to ensure an appropriate module of adaptive immune response. They interact with a serine protease called Grass, which initiates a proteolytic cascade that terminates in the cleavage of the protein Spätzle. One of the cleaved fragments forms a homodimer that binds to Toll and induces its dimerization, which in turn stimulates the antimicrobial response. When the Spätzle dimer binds to Toll, hemocytes synthesize and secrete antimicrobial peptides. Relish induces expression of the antimicrobial peptides diptericin, attacin, and cecropin, which are distinct from the peptides induced by Toll signaling. Thus, the Toll and Imd pathways activate effector mechanisms to eliminate infection by different kinds of pathogens. The others are present in neutrophil granules and exert a bacteriostatic action through interactions with bacterial cell-wall peptidoglycan. Top panel: immature dendritic cells in the skin are highly phagocytic and macropinocytic, but lack the ability to activate T lymphocytes. Dendritic cells residing in the skin ingest microbes and their products and degrade them. During a bacterial infection, the dendritic cells are activated by various innate sensors and the activation induces two types of changes. Second panel: the dendritic cells migrate out of the tissues and enter the lymphatic system and begin to mature. They lose the ability to ingest antigen but gain the ability to stimulate T cells. Cleavage alters the conformation of Spätzle, enabling it to bind Toll and induce Toll dimerization (second panel). Fungal recognition also leads to cleavage of Spätzle and the production of antimicrobial peptides by this pathway, although the recognition proteins for fungi are as yet unidentified. The sea urchin also has an increased number of proteins that are likely to be involved in signaling from these receptors, there being, for example, four genes that are similar to the single mammalian MyD88 gene. A similar expansion of innate receptors has occurred in some chordates, the phylum to which vertebrates belong. Amphioxus (the lancelet) is a nonvertebrate chordate lacking an adaptive immune system. Innate immune cells express several receptor systems that recognize microbes and induce rapid defenses as well as delayed cellular responses. Several scavenger and lectin-like receptors on neutrophils, macrophages, and dendritic cells help rapidly eliminate microbes through phagocytosis. The signaling pathways activated by all of these primary sensors of pathogens induce a variety of genes, including those for cytokines, chemokines, and co-stimulatory molecules that have essential roles in immediate defense and in directing the course of the adaptive immune response later in infection. We will now examine the responses of innate immunity induced as an immediate consequence of pathogen recognition by the sensors described in the last section. We will focus on the major phagocytes-neutrophils, macrophages, and dendritic cells-and the cytokines they produce that induce and maintain inflammation. First, we will introduce the families of cytokines and chemokines that coordinate many cellular responses, such as the recruitment of neutrophils and other immune cells to sites of infection. We will discuss the various adhesion molecules that are induced on immune cells circulating in the blood and on endothelial cells of blood vessels to coordinate movement of cells out of the blood and into infected tissues. We will consider in some detail how macrophage-derived chemokines and cytokines promote the continued destruction of infecting microbes. This is achieved both by stimulating the production and recruitment of fresh phagocytes and by inducing another phase of the innate immune response-the acute-phase response-in which the liver produces proteins that act as opsonizing molecules, helping to augment the actions of complement. They respond to early cytokine signals provided by innate sensor cells, and amplify the response by producing various types of effector cytokines. If an infection is not cleared by the induced innate response, an adaptive response will ensue that uses many of the same effector mechanisms used by the innate immune system but targets them with much greater precision. The effector mechanisms described here therefore serve as a primer for the focus on adaptive immunity in the later parts of this book. Cytokines are small proteins (about 25 kDa) that are released by various cells in the body, usually in response to an activating stimulus, and that induce responses through binding to specific receptors. Cytokines can act in an autocrine manner, affecting the behavior of the cell that releases the cytokine, or in a paracrine manner, affecting adjacent cells. Some cytokines are even stable enough to act in an endocrine manner, affecting distant cells, although this 108 Chapter 3: the Induced Responses of Innate Immunity depends on their ability to enter the circulation and on their half-life in the blood. However, not all cytokines are included in this system; thus students of immunology are still faced with a somewhat confusing and difficult task. Most members of this family are produced as inactive proproteins that are cleaved (removing an amino-terminal peptide) to produce the mature cytokine. The hematopoietin superfamily of cytokines is quite large and includes non-immune-system growth and differentiation factors such as erythropoietin (which stimulates red blood cell development) and growth hormone, as well as interleukins with roles in innate and adaptive immunity. Many of the soluble cytokines made by activated T cells are members of the hematopoietin family. The receptors for the hematopoietin cytokines are tyrosine kinase-associated receptors that form dimers when their cytokine ligand binds. Many cytokines signal through receptors of the hematopoietin receptor superfamily, named after its first member, the erythropoietin receptor. The hematopoietin receptor superfamily includes homodimeric and heterodimeric receptors, which are subdivided into families on the basis of protein sequence and structure. Heterodimeric class I cytokine receptors have an chain that often defines the ligand specificity of the receptor; they may share with other receptors a common or chain that confers the intracellular signaling function. Some types of cytokine receptors are composed of two identical subunits, but others have two different subunits. An important feature of cytokine signaling is the large variety of different receptor subunit combinations that occur. These cytokines and their receptors can also be further divided into subfamilies characterized by functional similarities and genetic linkage. In addition, they bind to closely related receptors, which belong to the family of class I cytokine receptors. They are usually found as homotrimers of a membrane-bound subunit, although some heterotrimers consisting of different subunits also occur. These receptors have a 7-transmembrane structure and signal by interacting with G-proteins as described in Section 3-2. For example, Jak3 is used by c for signaling by several of the cytokines described above. They then translocate to the nucleus, where they bind to and activate the transcription of a variety of genes important for adaptive immunity. Since signaling by these receptors depends on tyrosine phosphorylation, dephosphorylation of the receptor complex by tyrosine phosphatases is one way that cells can terminate signaling. Cytokine signaling can also be terminated by negative feedback involving specific inhibitors that are induced by cytokine activation. This is one way in which appropriate immune responses can be selectively activated, as the released cytokines orchestrate the next phase of host defense. It also has systemic effects, many of which are harmful (discussed in Section 3-20). The two groups of chemokines act on different sets of receptors, all of which are G-proteincoupled receptors. Different receptors are expressed on different cell types, and so a particular chemokine can be used to attract a particular cell type. Fractalkine is unusual in several respects: it has three amino acid residues between the two cysteines, and it exists in two forms, one that is tethered to the membrane of the endothelial and epithelial cells that express it, where it serves as an adhesion protein, and a soluble form that is released from the cell surface and acts as a chemoattractant for a wide range of cell types. Among the cytokines released by tissues in the earliest phases of infection are members of a family of chemoattractant cytokines known as chemokines. These small proteins induce directed chemotaxis in nearby responsive cells, resulting in the movement of the cells toward the source of the chemokine. All the chemokines are related in amino acid sequence, and their receptors are G-protein-coupled receptors (see Section 3-2). Chemokines can be produced and released by many different types of cells, not only those of the immune system. In the immune system they function mainly as chemoattractants for leukocytes, recruiting monocytes, neutrophils, and other effector cells of innate immunity from the blood into sites of infection. They also guide lymphocytes in adaptive immunity, as we will learn in Chapters 9­11. Some chemokines also function in lymphocyte development and migration and in angiogenesis (the growth of new blood vessels). There are more than 50 known chemokines, and this striking multiplicity may reflect their importance in delivering cells to their correct locations, which seems to be their main function in the case of lymphocytes. First, they act on the leukocyte as it rolls along endothelial cells at sites of inflammation, converting this rolling into stable binding by triggering a change of conformation in the adhesion molecules known as leukocyte integrins. These conformational changes enable integrins to bind strongly to their ligands on the endothelial cells, which allows the leukocyte to cross the blood vessel walls by squeezing between the endothelial cells. Second, the chemokine directs the migration of the leukocyte along a gradient of chemokine molecules bound to the extracellular matrix and the surfaces of endothelial cells. Chemokines are produced by a wide variety of cell types in response to bacterial products, viruses, and agents that cause physical damage, such as silica, alum, or the urate crystals that occur in gout. Thus, infection or physical damage to tissues induces the production of chemokine gradients that can direct phagocytes to the sites where they are needed. The recruitment of monocytes occurs simultaneously, but they accumulate more slowly at the site of infection, perhaps because they are less abundant in the circulation. We will return to the chemokines in later chapters, where they are discussed in the context of the adaptive immune response. Now, however, we turn to the molecules that enable leukocytes to adhere to the endothelium, and we shall then describe step by step the extravasation process by which monocytes and neutrophils enter infected sites. Recruitment occurs as part of the inflammatory response and is mediated by cell-adhesion molecules that are induced on the surface of the endothelial cells of local blood vessels. Here we 114 Chapter 3: the Induced Responses of Innate Immunity consider those functions that participate in the recruitment of inflammatory cells in the hours to days after the establishment of an infection. As with the complement components, a significant barrier to understanding the functions of cell-adhesion molecules is their nomenclature. Most adhesion molecules, especially those on leukocytes, which are relatively easy to analyze functionally, were originally named after the effects of specific monoclonal antibodies directed against them. Three structural families of adhesion molecules are important for leukocyte recruitment. The selectins are membrane glycoproteins with a distal lectin-like domain that binds specific carbohydrate groups. Several structural families of adhesion molecules have a role in leukocyte migration, homing, and cell­cell interactions: the selectins, the integrins, and proteins of the immunoglobulin superfamily. The figure shows schematic representations of an example from each family, a list of other family members that participate in leukocyte interactions, their cellular distribution, and their ligand in adhesive interactions. The family members shown here are limited to those that participate in inflammation and other innate immune mechanisms. The same molecules and others participate in adaptive immunity and will be considered in Chapters 9 and 11. The nomenclature of the different molecules in these families is confusing because it often reflects the way in which the molecules were first identified rather than their related structural characteristics.

The timing of selected local potentials is shown to illustrate that these sites are localized to deceleration zones propagating into the latest regions of activation erectile dysfunction injection test 100 mg intagra otc. The timing of selected local potentials are shown to illustrate that these sites are localized to deceleration zones propagating into the latest regions of activation erectile dysfunction drugs available over the counter order 100 mg intagra with amex. The endocardial scar harbors a region of slower and later activation than the corresponding epicardial scar varicocele causes erectile dysfunction order intagra online now. We propose targeting deceleration zones that propagate into the latest activation region as the first step to substrate ablation erectile dysfunction herbal medications 100 mg intagra for sale. Only ripple mapping has the potential to represent continuous or multiple component activation at a single recording site erectile dysfunction what doctor to see buy intagra 75 mg without a prescription. However, as a total display of activation, the pattern of conduction within regions that are obscured by far-field components can usually be ascertained by using the information from neighboring electrograms when mapping density is sufficiently high. This data is consistent with early surgical observations limited to epicardial mapping. The advantage of using an isochronal display is the ease of visualizing areas of isochronal crowding, which represents a deceleration zone with the slowest conduction velocity. Mechanistically, this data suggests that reentry occurs in arrhythmogenic regions of scar with a degree of preexisting fixed conduction slowing or electrical discontinuity during sinus rhythm, although the barriers appear to be functionally determined. Validation and independent confirmation is necessary to advance these concepts further. A prospective trial comparing functional mapping during sinus with scar-based strategies is currently being planned. This approach may have greater specificity for sites critical for reentry than a voltage-based display. Elimination of local abnormal ventricular activities: A new end point for substrate modification in patients with scar-related ventricular tachycardia. Late potentials abolition as an additional technique for reduction of arrhythmia recurrence in scar related ventricular tachycardia ablation. Core isolation of critical arrhythmia elements for treatment of multiple scarbased ventricular tachycardias. Directional influences of ventricular activation on myocardial scar characterization: Voltage mapping with multiple wavefronts during ventricular tachycardia ablation. Electroanatomic left ventricular mapping in the porcine model of healed anterior myocardial infarction. Impact of substratebased ablation of ventricular tachycardia on cardiac mortality in patients with implantable cardioverter-defibrillators. Accuracy of combined endocardial and epicardial electroanatomic mapping of a reperfused porcine infarct model: A comparison of electrofield and magnetic systems with histopathologic correlation. Impact of local ablation on interconnected channels within ventricular scar: Mechanistic implications for substrate modification. Relationship between sinus rhythm late activation zones and critical sites for scarrelated ventricular tachycardia: Systematic analysis of isochronal late activation mapping. Localization of the isthmus in reentrant circuits by analysis of electrograms derived from clinical noncontact mapping during sinus rhythm and ventricular tachycardia. Reentrant ventricular arrhythmias in the late myocardial infarction period: Correlation of activation patterns of sinus and reentrant ventricular tachycardia. This is an effective strategy in patients with ischemic cardiomyopathy where complex fractionated electrograms, late potentials, and local abnormal ventricular activities can be targeted in sinus rhythm. Vasopressors or inotropes may be used, but the extent of hemodynamic support provided is usually inadequate. Prolonged use of these agents may also be cardiotoxic, with increased risk for multi-organ dysfunction, morbidity, and mortality. While hemodynamic support may be beneficial in both ischemic and nonischemic cardiomyopathy, the benefit may be greater in patients with nonischemic cardiomyopathy where substrate-based ablation is less effective. The voltage map shows numerous areas of late potentials (black points), fractionated electrograms (white points) in close proximity to the coronary arteries and phrenic nerve (blue points). Furthermore, Impella requires smaller arterial sheaths and obviates the need for additional venous access and transeptal puncture, which may potentially reduce complications and shorten implantation times. The balloon is positioned in the descending aorta, with the distal end of the balloon lying a few centimeters distal to the origin of left subclavian artery and the proximal end above the renal arteries. Inflation of the balloon in diastole augments the diastolic pressure and improves coronary and peripheral blood flow. Contrast is administered to ensure the level of access and to rule out significant peripheral arterial disease. After confirming the appropriate positioning of the device with fluoroscopy and intracardiac echocardiography, the device is turned on and titrated up to its full support capability. Proper device positioning should then be reconfirmed using the positioning waveform on the console. Panel A: Left common femoral artery access is confirmed by performing an angiogram followed by placement of an 8-Fr sheath. Panel B: "Preclosure" is performed by placing 2 orthogonally placed Perclose devices, which are secured to the field using clamps (arrows). The guidewire is advanced into the chamber and left in place while the pigtail catheter is removed. If epicardial mapping and ablation is planned as the primary strategy, pericardial access may be obtained at the start of the procedure and the Impella placement is withheld until the lack of pericardial bleeding confirmed. If there is evidence of pericardial bleeding that can be easily drained and controlled, epicardial mapping may be performed to allow tissue healing prior to initiating anticoagulation and placement of Impella. In this latter scenario, the device should either be completely removed or temporarily withdrawn into the descending aorta with the purge solution and a low performance level maintained to avoid clot formation. At the highest performance levels and when the mapping catheter was intentionally positioned near the Impella motor, the magnetic interference resulted in high-frequency noise on the mapping catheter channel (arrow), the ablation catheter was temporarily no longer visible on the C arto 3D map (Biosense Webster), and new location points could not be acquired. Panel B: As the ablation catheter is advanced to a location adjacent to the motor of the Impella, the C arto system now shows that force reading is high and the screen flashes red. Additionally, the location of the catheter on the system is no longer accurate as the catheter is now seen at remote location (arrow). TandemHeart the TandemHeart device is a percutaneous left atrial to femoral artery bypass system, which uses an external centrifugal pump that provides up to 3. Femoral venous access is obtained followed by transseptal puncture and dilation to accommodate the 21-Fr inflow cannula in the left atrium. The position of transseptal cannula is then confirmed fluoroscopically by injecting dye into the cannula to make sure that all its side ports are across the interatrial septum. Alternatively, intracardiac echocardiogram can also be used to confirm the position of the cannula. Femoral artery angiogram is obtained to ensure that the puncture is above the level of common femoral artery bifurcation and to rule out significant peripheral arterial disease. The transseptal and the arterial cannulae are then connected to the respective ports in the external pump. The device is typically programmed to 3000 to 7500 rpm and titrated to achieve desired hemodynamic support. A major limitation of TandemHeart is the need for large venous and arterial accesses thereby increasing the risk of vascular complications. Arterial blood pressure and pulse oximetry alone are suboptimal for hemodynamic monitoring, especially in Table 57. Hemodynamic support described as adequate (mean arterial pressure > 60 mm Hg) to permit sufficient activation mapping in all except for 2 patients with Impella. While cerebral autoregulation is preserved until mean arterial pressures of 50 to 60 mm Hg, the actual blood pressure levels required to maintain adequate cerebral perfusion in any given individual are highly variable. This is further compounded by lower systolic blood pressures and higher diastolic blood pressures resulting from continuous flow pumps. Continuous bispectral monitoring reflects the depth of anesthesia, but not sensitive enough to detect early hypoperfusion. Transcranial Doppler ultrasonography can detect early cerebral hypoperfusion, but is cumbersome and operator dependent. In contrast to pulse oximetry, SctO2 does not require pulsatile flow for accurate measurement, which is an especially attractive feature when nonpulsatile flow devices are used for hemodynamic support. Since SctO2 is an indirect measure of cerebral perfusion pressure (the mean arterial pressure minus central venous pressure), this may provide additional clinically relevant information to guide our decisions regarding volume status, inotrope use, as well as the timing of extubation. Panel B: Real-time data showing the trend in cerebral oximetry on the left and right sides. In addition to cerebral oximetry, we also routinely monitor body temperature, arterial blood glasses, electrolytes, urine output, serum lactate, and pressor requirement at least every 30 minutes during the procedure to ensure that overall patient condition is not trending in a negative direction. In patients with severe heart failure or cardiogenic shock, the greater degree of hemodynamic support provided by the Impella 5. Potential complications of the TandemHeart system include cardiac tamponade, bleeding, critical limb ischemia, sepsis, arrhythmias, and residual atrial septal defects. The potential benefits of hemodynamic support devices need to be weighed against the risk of complications, longer procedural time, and incremental cost associated with their use. Scar homogenization versus limited-substrate ablation in patients with nonischemic cardiomyopathy and ventricular tachycardia. How to perform ventricular tachycardia ablation with a percutaneous left ventricular assist device. Activation and entrainment mapping of hemodynamically unstable ventricular tachycardia using a percutaneous left ventricular assist device. Percutaneous cardiopulmonary support for catheter ablation of unstable ventricular arrhythmias in high-risk patients. Efficacy and safety of ventricular tachycardia ablation with mechanical circulatory support compared with substrate-based ablation techniques. Catheter ablation of hemodynamically unstable ventricular tachycardia with mechanical circulatory support. Percutaneous left ventricular assist devices in ventricular tachycardia ablation: Multicenter experience. Procedural and clinical outcomes after catheter ablation of unstable ventricular tachycardia supported by a percutaneous left ventricular assist device. Outcomes of ventricular tachycardia ablation using percutaneous left ventricular assist devices. The proximal face of the device is covered with a 160-micron membrane to block emboli and promote endothelialization of the device. As a general principle, the screening study confirms the presence of suitable anatomy and the absence of contraindications, while selection of device size is based on intraprocedural measurements, which can change between the time of the screening study and the procedure. There is a small body of experience using intracardiac echocardiography to guide implantation, but caution should be used until more data is available. Patient Preparation Our preference is to perform the procedure under uninterrupted anticoagulation. Due to the inherent risk of perforation, centers new to the experience may prefer to perform the procedure with brief interruption of anticoagulation or bridging therapy. On arrival to the preoperative suite, patients receive antibiotic prophylaxis per hospital protocol. In the United States, the implant procedure is performed with general anesthesia using endotracheal intubation. Venous Access and Transseptal Puncture Femoral venipuncture is performed via the modified Seldinger technique using a long guidewire (typically 180 cm) advanced to the superior vena cava. A skin nick and dilation of the cutaneous tract are recommended to accommodate the 14-Fr outer diameter/12-Fr inner diameter Watchman access sheath. Transseptal puncture is performed with a standard technique per operator discretion. The transseptal sheath is advanced to the superior vena cava, the wire is removed, and the transseptal needle is inserted into the sheath after flushing. We confirm a mid posterior puncture site (mid fossa in the bicaval view and posterior in the short axis view). Sheath Exchange the needle/dilator assembly is replaced with an exchangelength stiff guidewire. The guidewire is advanced into a left pulmonary vein to enable non-traumatic sheath exchange. The single-curve can be considered in the rare case of an unusually posterior target, while the anterior curve can be used in cases of a very anterior appendage take-off. Panel B: Short-axis view demonstrating target site in the posterior septum (green arrow). The most superior/anterior lobe of the appendage is the preferred target and is typically engaged using counterclockwise torque (keeping the pigtail outside the sheath) to allow optimal coaxial placement of the face of the device. Placement in a posterior lobe typically leaves a large shoulder, and should be avoided if possible (Video 58. In clinical trials, air embolism was an early complication that improved significantly with operator experience and attention to fastidious flushing of the delivery system. Once the device is fully prepared and free of any air, the patient is prepared for apnea. The typical duration of apnea is 1­3 minutes and with appropriate preparation and paralytics, the anesthesiologist is able to provide this without incident. Once the pigtail has been removed, there should be no forward motion of the sheath. In this instance, the sheath should be pulled back slowly until there is brisk backflow. To minimize any potential introduction of air when inserting the delivery catheter into the sheath, there are two techniques that can be employed. A fluid-to-fluid interface can be used by merging a forward saline flush from the delivery catheter to the brisk backflow of the delivery sheath.

The black arrow points to the circular mapping catheter that is continuously dragged erectile dysfunction exam video 75 mg intagra mastercard. Alternatively erectile dysfunction treatment shots 25 mg intagra purchase otc, the SmartTouch catheter can be used with the same parameters but a higher flow rate at 30 cm3/min erectile dysfunction doctors in tallahassee purchase 75 mg intagra fast delivery. At the posterior site close to the esophagus erectile dysfunction shake cure discount 75 mg intagra mastercard, energy delivery is discontinued when the esophageal temperature probe has a rapid increase and reaches 39°C erectile dysfunction symptoms best purchase intagra, while the power is reduced if the temperature slowly increases. Continuous impedance monitoring and catheter tip temperature are also employed to minimize the risk of steam pops. To avoid hypotension, phenylephrine is used at dosages tailored to individual patients in accordance with baseline blood pressure. The initiating beat activation sequence is identified and compared with the sinus beat activation sequence. Once the area of interest was identified, additional mapping is performed either with the ablation catheter or with the circular mapping catheter to determine the earliest activation. The timing of the local electrograms in relation to the P wave is always used to identify the site of earliest activation. It is not easy to create a single continuous, transmural lesion, and even a single gap in the ablation line results in reconnection of the whole posterior wall. In electrogram-based ablation, all potentials identified moving the multielectrode catheter along the posterior wall are sequentially targeted. The endpoint is to achieve electrical isolation, as documented by the absence of any electrical activity in the posterior wall. In brief, the circular mapping catheter is positioned at the posterior wall and ablation is delivered to abolish potentials recorded by the mapping catheter. Ablation is started distally and continued along the vein to reach the vessel ostium. Oral anticoagulation was continued for a minimum of 6 months after the blanking period, whereas antiarrhythmic drugs were administered only during the blanking period. Each patient is advised to check body weight and to call in if this does not drop to the preprocedure value. All patients are strictly monitored for outcome and complications during overnight hospital stay, and on the following day prior to discharge using symptom assessment, serial neurological examinations, and puncture site checks. A 48-hour or 7-day Holter monitor recording is obtained at 3, 6, 9, 12, and 15 months postablation. Additionally, all patients were given an event recorder for 5 months and were asked to transmit recordings 4 times a week even when asymptomatic and anytime they experienced symptoms. In case of symptoms or suspected complications, patients are asked to seek medical attention at either a local emergency department or our emergency department, or to follow up with their primary physician. We follow a standard, uniform, and validated protocol of long-term postprocedural anticoagulation management. Feasibility and safety of dabigatran versus warfarin for periprocedural anticoagulation in patients undergoing radiofrequency ablation for atrial fibrillation: Results from a multicenter prospective registry. Periprocedural stroke and management of major bleeding complications in patients undergoing catheter ablation of atrial fibrillation: the impact of periprocedural therapeutic international normalized ratio. Safety and efficacy of novel oral anticoagulants in the setting of atrial fibrillation ablation: Is it time to celebrate the "funeral" of warfarin Feasibility and safety of uninterrupted rivaroxaban for periprocedural anticoagulation in patients undergoing radiofrequency ablation for atrial fibrillation: Results from a multicenter prospective registry. Feasibility and safety of uninterrupted periprocedural apixaban administration in patients undergoing radiofrequency catheter ablation for atrial fibrillation: Results from a multicenter study. Does periprocedural anticoagulation management of atrial fibrillation affect the prevalence of silent thromboembolic lesion detected by diffusion cerebral magnetic resonance imaging in patients undergoing radiofrequency atrial fibrillation ablation with open irrigated catheters Pulmonary vein antrum isolation for atrial fibrillation on therapeutic coumadin: Special considerations. How to identify and treat patient with pulmonary vein stenosis post atrial fibrillation ablation. Clinical impact of heparin kinetics during catheter ablation of atrial fibrillation: Meta-analysis and meta-regression. Heparin kinetics: the "Holy Grail" of periprocedural anticoagulation for ablation of atrial fibrillation. Impact of systematic isolation of superior vena cava in addition to pulmonary vein antrum isolation on the outcome of paroxysmal, persistent, and permanent atrial fibrillation ablation: Results from a randomized study. Left atrial posterior wall isolation reduces the recurrence of atrial fibrillation: A meta-analysis. Atrial fibrillation termination as a procedural endpoint during ablation in long-standing persistent atrial fibrillation. Ablation for longstanding permanent atrial fibrillation: Results from a randomized study comparing three different strategies. Post-procedural anticoagulation regimen determines stroke risk following left atrial appendage electrical isolation in atrial fibrillation patients undergoing catheter ablation. The overall incidence of atrial esophageal fistula with cryoablation appears to be considerably less than compared to the rate observed with radiofrequency ablation. Simply, the flowing blood pool increases the available heat sink area, and consequently, it reduces the cryoballoon cooling potential and ultimately limits the final lesion size. Also, there are a number of anticoagulation strategies that may be used, and the ablation can be either performed on or off therapeutic anticoagulation. In addition, the choice of anticoagulation may include warfarin or a non-vitamin K­dependent anticoagulant. All patients will receive a transthoracic echocardiogram as part of the outpatient cardiovascular assessment. Anesthesia care is variable, with some operators using general anesthesia and others using conscious sedation. Prior to insertion of the Flexcath Advance into the right femoral vein, a 10- or 11-Fr dilator may be used. A gentle but firm twisting motion may facilitate the insertion of the Flexcath Advance. The Flexcath Advance is advanced across the interatrial septum with steady pressure and the dilator is given a counter clockwise quarter turn to disengage the dilator from the sheath prior to advancement of the sheath itself across the septum. After the dilator is removed, the sheath should be carefully flushed by tapping the handle to release trapped air and connect it to a low-flow drip saline bag at 1­3 cc/min. Other sheaths may be used for a coronary sinus catheter and/or the pacing catheter used for diaphragmatic pacing (see below). The initial 8-Fr right femoral vein access should have a shallow angle of entry to ease the eventual exchange for the Flexcath Advance Sheath. Transseptal puncture through the thicker portion of the septum at the inferior limbus may also provide a reduction of iatragenic atrial septal defect from the large sheath access. To reduce complication and improve outcome, several maneuvers and rules can be utilized. The inflation pressure of the cryoballoon is low pressure and is unlikely to cause mechanical trauma. Ablation then should be initiated, and allow 2 to 3 seconds prior to the advancement of the cryoballoon back into the best occlusion/contact position. If a leak is detected during the venogram, small adjustments with additional pressure toward the side of the leak will often secure occlusion at an optimal location. A second application of ablation should then be performed with the cryoballoon deflected toward the inferior aspect of the vein so that the lesions have overlapped. Dosing with cryoballoon has not been as well defined, but it is recommended that the total ablation time at any setting should not exceed 180 seconds. Maneuvering of the cryoballoon after initiation of ablation should be avoided to prevent tissue injury. The operator should not move the balloon catheter until the catheter temperature reading reaches 35°C to avoid tissue trauma with residually frozen tissue. Ablation should then be initiated for 2­3 seconds to increase the cryoballoon pressure prior to reengaging the balloon at the antrum at the ostium. Although the initial recommended ablation time for the second-generation cryoballoon was 4 minutes, subsequently the ablation time has been reduced to 3 minutes to avoid collateral tissue injury. The time and balloon­tissue contact are controlled by the operator, and time directly impacts the lesion depth-longer ablation time correlates to a deeper lesion. The displayed temperature on the CryoConsole is the return gas temperature, not the actual tissue temperature. When the displayed temperature is below ­55°C to ­60°C, ablation should be terminated early, and repositioning of the cryoballoon at a more antral position may be needed. Right phrenic nerve palsy is the most common complication associated with cryoballoon ablation, and the risk for persistent phrenic nerve impairment can be minimized by ensuring the cryoballoon position is as antral as possible. Vigilant monitoring of the phrenic nerve during ablation, and terminating ablation immediately at the first sign of phrenic nerve impairment, will make this complication much less frequent. Follow-Up Follow-up is performed by clinic visits with repeated 24-hour Holter or 7-day monitoring and event recorders. For the second procedure, cryoballoon therapy may be repeated, particularly if the first ablation was performed with the first-generation system or if previously anatomical obstacles can be overcome with additional experience or maneuvers to overcome the previous limitations. If femoral access has been obtained, the femoral arterial puncture may be closed with an Angioseal closure device (St. All patients are usually observed overnight for observation and discharged the following day. The complication rates described below are aggregated from interventions on 611 patients reported in the three large series of patients who underwent balloon cryoablation at five different European hospitals. This should be considered in the event of any unexpected deterioration in hemodynamic status, and we would strongly advise that any laboratory performing transseptal procedures should have echocardiography machines available at all times in the room. Atrioesophageal fistulas have been described in patients undergoing cryoablation but the incidence appears to be lower than that in patients with radiofrequency ablation. In the Fire and Ice Trial 2, patients had stroke or transient ischemic events in both the cryoablation arm and the radiofrequency ablation arm out of 374 and 376 patients, respectively. In this trial, while 10 patients had phrenic nerve injury at discharge, only two and one patients had phrenic nerve injury at 3 and 12 months, respectively. Injury to the right phrenic nerve can be minimized by our protocol of only using the 28-mm cryoballoon, limiting cryoballoon applications to two per vein, and pacing the right phrenic nerve. All cases of right phrenic nerve palsies in the three European series resolved within 14 months. There were no statistical differences between groups in the quality-of-life surveys. Impact of type of atrial fibrillation and repeat catheter ablation on longterm freedom from atrial fibrillation: Results from a multicenter study. Long-term followup of persistent atrial fibrillation ablation using termination as a procedural endpoint. Variations in pulmonary venous drainage to the left atrium: Implications for radiofrequency ablation. Catheter ablation for paroxysmal atrial fibrillation: Segmental pulmonary vein ostial ablation versus left atrial ablation. Longterm follow-up after cryothermic ostial pulmonary vein isolation in paroxysmal atrial fibrillation. Pulmonary vein isolation using transvenous catheter cryoablation for treatment of atrial fibrillation without risk of pulmonary vein stenosis. The Fire and Ice Trial as a randomized study involving centers experienced in both cryoablation and radiofrequency is the most relevant comparison of the two technologies. Balloon catheter ablation to treat paroxysmal atrial fibrillation: What is the level of pulmonary venous isolation Pulmonary venous isolation by antral ablation with a large cryo-balloon for treatment of paroxysmal and persistent atrial fibrillation: Medium-term outcomes and nonrandomised comparison with pulmonary venous isolation by radiofrequency ablation. Pulmonary vein isolation using an occluding cryoballoon for circumferential ablation: Feasibility, complications, and short-term outcome. One year followup after cryoballoon isolation of the pulmonary veins in patients with paroxysmal atrial fibrillation. Best practice guide for cryoballoon ablation in atrial fibrillation: the compilation experience of more than 3000 procedures. Reduction of iatrogenic atrial septal defects with an anterior and inferior transseptal puncture site when operating the cryoballoon ablation catheter. Recordings of diaphragmatic electromyograms during cryoballoon ablation for atrial fibrillation accurately predict phrenic nerve injury. Time-to-Effect Based Cryoballoon Dosing to Achieve Permanent Pulmonary Vein Isolation-The First Chronic Study in Canine Model. Balloons typically use alternative energy sources that may be more suited to circumferential ablation compared to radiofrequency energy. Thus far, balloon energy sources have included ultrasound,5-8 cryoablation,9,10 and now laser ablation. The second-generation balloon was a fixed-diameter balloon that came in 20-, 25-, and 30-mm diameter sizes. It was felt that compared to the 360° laser, a 90° arc would allow a more directed delivery of energy in a pattern that could be "stitched" together to create complete isolation. While such an approach was successful in preclinical animal and initial human studies, the noncompliant balloon and 90° arc made the ablation procedures challenging. The lesion generator produces a 30° arc of light energy and is powered by a 980-nm diode laser. One must be careful not to ablate with the laser in areas of stagnant blood, or coagulum (thrombus) can occur. The catheter and lesion generator are disposable; the endoscope can be resterilized and reused during subsequent procedures. The laser ablation system is deployed using a custom 12-Fr-inner-diameter, 16-Fr-outer-diameter 180° deflectable sheath. The sheath should be flushed with heparinized saline under pressure throughout the procedure.

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