Extra Super Levitra
In a direct strike or a side-ﬂash strike where the individual is relatively close to the object from which the bolt jumps buy discount extra super levitra on-line erectile dysfunction age, the current can either spread over the surface of the body or enter it cheap 100 mg extra super levitra with amex erectile dysfunction cure video, or it can follow both routes buy extra super levitra 100mg visa erectile dysfunction drugs walgreens. In most cases seen by the forensic pathologist, the current has both ﬂowed over the surface of the body and entered. In such cases, it is quite common to ﬁnd the clothing torn, shoes burst, hair seared, burns on the skin caused by zippers and other metal objects heated by the lightning, and burns caused by the entrance and exit of current. The torn clothing and burst shoes sometimes have led to misinterpretation of the nature of the injuries. People struck by lightning and found next to a road have been thought to be hit-and-run victims. If one is inside a metal vehicle, such as a car or train, when it is struck by lightning, the probability of injury is extremely small. On rare occasions, death or injury has been reported when an individual was using a telephone and the line was hit by lightning. With a direct hit by lightning, death is probably inevitable, because of burns and injury to the respiratory center of the brain. If the electrocution is secondary to a close point of impac- tion, survival may be possible. One of the lesions considered pathognomonic for lightning injury is the “arborescent” or fern-like injury of the skin called Lichtenberg ﬁgures (Figure 16. This lesion is a patterned area of transient erythema that appears within 1 h of the accident and then gradually fades within 24 h. Another pos- sibility is that it represents an entrance point in an individual struck by a positively charged lightning bolt. Both explanations, neither of which are exclusive of the other, would explain the relative rarity of the arborescent lesion in individuals struck by lightning. Hyperthermia and Hypothermia: the 17 Effects of Heat and Cold Normal body temperature is generally considered to be 98. Body temperature, however, can vary from individual to individual, by age, time of day, physical exertion, etc. Maintenance of normal body temperature is a delicate balance between heat load and heat loss. Heat load is the sum of heat generated by oxidation of metabolic products and heat acquired from the environment. For example, if an indi- vidual sits in a chair, heat conducted from the body will raise the temperature of the chair to that of the body. In contrast to limited heat loss by direct conduction, sizable quantities of heat can be lost by conduction to air. The molecules composing the skin transfer heat to contiguous air molecules, producing a thin zone of heated air adjacent to the skin. Once 419 420 Forensic Pathology this layer of air absorbs heat until it is equal to the temperature of the body, heat loss ceases. If, however, this layer of heated air is continually removed and new air introduced (by a fan or wind), the loss of heat by conduction will continue. This movement of air around the body, with resultant contin- ued loss of heat, is known as convection. Winds will blow away the layer of air immediately adjacent to the skin, thus accounting for the feeling of cold and increased heat loss when the wind blows. Once the wind has cooled the skin to a certain temperature, the rate at which heat ﬂows from the core of the body to the skin is the limiting factor in heat loss, rather than the rate of conduction and convection. If the environment becomes hotter than the body, radiant heat given up by the surroundings will exceed the loss of heat from the body by radiation. It occurs at a rate of about 600 mL per day, that is, a continual heat loss of 12-16 cal/h. The more important of the two methods of evaporation that produce cooling of the body is sweating. In hot weather, the maximum rate of sweat production varies from 700 mL/h in the unacclimatized person to 1. Dehydration, in turn, predisposes an individual to the development of hyperthermia and heat stroke. To prevent this, individuals exposed to high temperatures are urged to increase their ﬂuid intake. This is especially necessary in those engaging in strenuous activities such as man- ual labor or jogging. Symptoms occur when serum sodium levels decrease to <130 mmol/L, becoming severe at levels <125 mmol/L. When serum sodium drops below 120 mmol/L, more than 50% of individuals have seizures. When people are exposed to hot weather for several weeks, they begin to progressively sweat more and more. This Hyperthermia and Hypothermia: the Effects of Heat and Cold 421 doubles within 10 days, increasing up to three times as much within 6 weeks. When the rate of sweat secretion is very low, the sodium chloride concentration of the sweat is also very low because sodium and chloride are reabsorbed before they reach the surface of the body. As the rate of secretion becomes progressively greater, the rate of sodium chloride re-absorption does not increase equally, so that the concentration of sodium in the sweat can rise almost to the level of the plasma. Extreme sweating can deplete the extracellular ﬂuids of electrolytes, particularly sodium and chloride. Thus, extra sodium and chloride must usually be added to the diet in tropical climates. Persons who sweat pro- fusely can lose as much as 15–30 g of sodium chloride each day until they become acclimatized. A person who has lived in the tropics since childhood actually has more active sweat glands in the body than an indi- vidual from a cold climate. When they live in a temperate zone, many of these become permanently inactive during childhood. Fat is especially important because it conducts heat only one third as readily as other tissues. When no blood is ﬂowing from internal organs to the skin, the insulating properties of the male body are approximately equal to three fourths the insulating properties of the usual suit of clothes. Increased loss of heat from the body can be caused by increased ﬂow of blood to the skin. Immediately beneath the skin is a venous plexus that is supplied by an inﬂow of blood. Full dilatation of these vessels can increase the rate of heat transfer to the skin eightfold. Such a high rate of blood ﬂow causes heat to be conducted from the internal portions of the body to the skin with great efﬁciency. Reduction in the rate of blood ﬂow decreases the efﬁciency in heat conduction, Thus, the skin is used as a radiator system, with the ﬂow of blood to the skin the mechanism of heat transfer from the body core to the skin. As long as the body temperature is greater than that of the surroundings, heat is lost principally by radiation and conduction.
Inhibitors of the corresponding gene products are thus predicted to exert a beneficial effect and lack 4 serious on-target adverse effects 100 mg extra super levitra amex erectile dysfunction doctors in lafayette la. Time Course of Drug Effects With repeated doses buy cheap extra super levitra on line erectile dysfunction drugs muse, drug levels accumulate to a steady state purchase extra super levitra with a mastercard erectile dysfunction clinic, the condition under which the rate of drug administration is equal to the rate of drug elimination in any given period. Drug accumulation to steady state is near-complete in four to five elimination half-lives (Fig. For many drugs, the target molecule is in plasma or readily accessible from plasma, so this time course also describes the development of pharmacologic effects. In other cases, however, although steady-state plasma concentrations are achieved in four to five elimination half-lives, steady-state drug effects take longer to achieve; there are several possible explanations for this. Second, time may be required for translation of the drug effect at the molecular site to a physiologic endpoint. Third, penetration of a drug into intracellular or other tissue sites of action may be required before development of a drug effect. One mechanism underlying such penetration is the variable function of specific drug uptake and efflux transport proteins that control intracellular drug concentrations. Left, The hash lines on the abscissa each indicate one elimination half-life (t1/2). When a loading bolus is administered with the maintenance infusion (blue), plasma concentrations are transiently higher but may dip, as shown here, before achieving the same steady state. When the same drug is administered by the oral route, the time course of drug accumulation is identical (magenta); in this case the drug was administered at intervals of 50% of a t1/2. Steady-state plasma concentrations during oral therapy fluctuate around the mean determined by intravenous therapy. Right, This plot shows that when dosages are doubled, or halved, or the drug is stopped during steady-state administration, the time required to achieve the new steady state is four or five half-lives and is independent of the route of administration. One of the great success stories of modern cardiovascular genetics has been the use of linkage analysis in large families to identify disease-causing rare variants (mutations) in familial syndromes with highly unusual clinical phenotypes, such as familial hypercholesterolemia (see Chapter 48), hypertrophic cardiomyopathy (see Chapter 78), and the ion channelopathies (see Chapter 33). Linkage analysis has not been widely applied to study pharmacogenomics because large kindreds with multiple individuals having clearly defined drug-response phenotypes generally are not available. Methods are available to establish the extent to which that variability includes a heritable component, often by examining twins, large families, or groups of families; evidence for heritability provides strong justification for pursuing studies to identify contributing genetic variation. The extent that rare and common variants contribute to this variability is only now being addressed. It has been speculated that common variants with large effects on drug response can persist in a population because there is no evolutionary pressure against such variants since drug exposure is a recent event in human history. Of note, rarer variants in these (or other) genes are only now being described, so their role in mediating drug response is much less well understood. In addition, virtually all studies to date have focused primarily on populations of European ancestry, and data are only now being generated on specific polymorphisms mediating variable drug actions in other ancestries. The association between polymorphisms in these candidate genes and the phenotype under study is then examined in persons with well-characterized phenotypes. The candidate gene approach is intuitively appealing because it takes advantage of what is known about underlying physiology. Despite this appeal, however, the method is now recognized to carry with it the great potential for false-positive associations, especially when small numbers of participants are studied. An important exception has been in pharmacogenomics, where the candidate gene approach has yielded important and clinically reproducible associations between single common polymorphisms and drug response. The great advantage of the method is that it is unbiased, in that it makes no assumptions about underlying physiology, and one of its major accomplishments has been to identify 8 entirely new pathways underlying variability in human traits. New technologies being developed to generate other types of high-dimensional data similarly hold the promise of elucidating new biologic pathways in disease and drug response. Advances in mass spectrometry are similarly enabling development of catalogs (proteomic and metabolomic profiling) of all proteins or of small-molecule metabolites of cellular processes, including drug metabolites, by cell and disease. Integrating these diverse data types into a comprehensive picture of the perturbations that result in disease or variable drug responses is the goal of the evolving discipline of systems biology and pharmacology. It has been proposed that future drug development would be better served by a focus on 13 pathways identified by systems approaches rather than single targets. High-Risk Pharmacokinetics When a drug is metabolized and excreted by multiple pathways, absence of one of these pathways, because of genetic variants, drug interactions, or dysfunction of excretory organs, generally does not affect drug concentrations or actions. By contrast, if a single pathway plays a critical role, the drug is more likely to exhibit marked variability in plasma concentration and associated effects, a situation that has been termed high-risk pharmacokinetics (Fig. In this case, genetic variants or co-administration of a drug that inhibits the pathway will lead to failure of bioactivation and loss of drug effect. In this case, genetic variants, co-administration of a drug that inhibits the pathway, or the presence of liver or kidney disease can inhibit drug elimination and thus lead to exaggerated drug action. This occurs because clinically important alternate pathways for drug elimination are absent, and increases in plasma parent drug concentrations can translate into serious drug toxicity. Note also that genetic variants or co- administered drugs that increase the rate of elimination will lead to decreased drug action. In this case, absence of activity of that pathway will lead to marked accumulation of drug in plasma, and for many drugs, such accumulation results in a high risk of drug toxicity. Similarly, administration of a wide range of P- glycoprotein inhibitors will predictably elevate plasma concentration of digoxin, which is eliminated primarily by P-glycoprotein–mediated efflux into bile and urine (see Table 8. This variant is rare in patients of African ancestry, 17 who therefore often require higher doses to avoid transplant rejection. The heart rate slowing and blood pressure effects of beta blockers and beta agonists have been associated with polymorphisms in the drug targets, the beta-1 and beta-2 receptors. Furthermore, allele frequencies vary strikingly by ancestry, probably accounting for warfarin dose 20 requirements being low in Asian patients and high in African patients compared with white patients. Lower rosuvastatin doses are also suggested in patients of Asian ancestry, and variants in multiple genes have been implicated. Similarly, sodium channel– blocking drugs also can bring out latent Brugada syndrome. The anticancer drug trastuzumab is effective only in patients with cancers that do not express the Her2/neu receptor. Because the drug also potentiates anthracycline-related cardiotoxicity, toxic therapy can be avoided in patients who are receptor negative (see Chapter 95). Indeed, the development of new “targeted” anticancer drugs has seen an increase in multiple types of cardiovascular adverse effects, including arterial and venous thrombosis, cardiomyopathy, myocarditis, and arrhythmias. Understanding the pathways leading to these effects could inform new approaches to prevent treat cardiovascular 22 disease more broadly. Optimizing Drug Doses The goals of drug therapy should be defined before the initiation of drug treatment. These may include acute correction of serious pathophysiology, acute or chronic symptom relief, or changes in surrogate endpoints (e. When the goal of drug therapy is to correct acutely a disturbance in physiology, the drug should be administered intravenously in doses designed to achieve a therapeutic effect rapidly.
With large hard stools purchase extra super levitra overnight online doctor erectile dysfunction, tion discount extra super levitra online erectile dysfunction recreational drugs, and anorexia nervosa can frst be recognized by a the child will not want to defecate because of the pain report of constipation cheap extra super levitra 100mg with visa erectile dysfunction treatment nyc. Fecal Soiling of Underpants Abdominal distention is frequently not marked in pa- Repeated fecal soiling, from involuntary passage of tients with functional constipation but can be present small amounts of feces into the underpants of children with other causes. This is or abnormal bowel sounds can indicate an organic generally caused by functional megacolon secondary cause such as obstruction. Palpable abdominal masses Refexes and Spinal Level or organomegaly point to an organic cause. Biceps C5, C6 Brachioradial C5, C6 Perform Digital Rectal Examination Triceps C6, C7, C8 Patellar L2, L3, L4 On perianal inspection, look for skin excoriation, Achilles S1, S2 skin tags, fssures, strictures, tears, or hemorrhoids, any of which can cause painful defecation. More advanced lesions are linear or elliptical breaks Perform a Focused Neurological Examination in the skin. Long-standing fssures are deep and Test relevant deep tendon and superfcial refexes. Internal fssures are seen when the anal terruption of T12-S3 nerves causes loss of voluntary sphincter relaxes as the examining fnger is with- control of defecation (Table 10-1). A normal anal indicates blood in the stool, which can be the result of sphincter with an empty rectal ampulla can indicate ulcerative or malignant lesions. In functional constipation, ex- test in detecting colorectal cancers and adenomas ranges pect to fnd a large dilated rectum full of stool. It is an inexpensive and noninvasive sphincter tone, both at resting and with a squeezing method to screen for bleeding lesions. Sphincter tone is increased in functional prob- rial testing can be done using stool cards at home that lems and strictures but is decreased in neurological are returned by mail for analysis. The presence of a mass in the rectum indi- ning at age 50 years, is one of the recommended screen- cates an impaction or obstructive lesion. Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology, Gastroenterology 134: 1570, 2008. A light source is peroxidase, so food restrictions before the test are not necessary; a head lamp is preferable. The barium en- ema in children is reserved to rule out Hirschsprung Complete Blood Count disease. Hematocrit and hemoglobin levels will be below the expected reference range with a bleeding Colon Transit Studies lesion. Colon transit studies are useful for patients with severe chronic constipation that responds poorly to Serum Electrolytes treatment. Severely ill patients can develop hypokalemia and hy- percalcemia, which are causes of constipation. Patients Anorectal Manometry on thiazide diuretics can develop hypokalemia and This test measures the pressure of the anal sphincter subsequent constipation. Alternatively, the pressure roidism such as sparse, coarse, dry hair; hirsutism; dry can be measured with a balloon manometry system, skin; or hoarse speech. A Urinalysis balloon at the tip of the probe is infated to determine A urinalysis and culture should be done if a child whether the patient feels a sensation of rectal fullness has an associated rectosigmoid impaction because of and an urge to defecate. On abdominal dividuals, frst consider functional causes, particularly examination, feces-flled bowel may be palpable. Idiopathic Slow Transit This condition is most common in older people, especially Simple Constipation those who are less active and have inadequate dietary fber Typically individuals with simple constipation report a and fuid intake. These patients experience decreased diet low in fber and bulk and/or inadequate fuid in- stool frequency; stools are typically dry and hard. They also often report pain before and with bowel movements because Hirschsprung Disease (Congenital Aganglionic of the hard, dry nature of the stools. The physical examination of the Hirschsprung disease is present from birth and is usu- abdomen and rectum is normal. No diagnos- meconium stool can indicate Hirschsprung disease in tic workup is needed unless the patient does not re- infants. Evidence of Functional causes of constipation include poor bowel stiffening, squeezing, and crying indicates stool is be- habits; inadequate intake of dietary fber, bulk, and ing propelled to the rectum. The abdomen may or may not be dis- Because defecation is painful with an anorectal lesion, tended. With the eventual passage of Functional constipation is seen in children who hard stools, the patient can report blood on the surface have large, hard stools that become diffcult or painful of the stool, on the toilet paper, or in the toilet. The resulting fecal retention sets up a cycle in digital rectal examination, look for hemorrhoids (rare which the sensitivity of the defecation refex and the in children), fssures, tears, or abrasions. The external of chronic laxative use or taking medications that can sphincter is intact. Stool may test positive for occult Fecal impaction is common in older adults and in those blood. The passage of hard stools at adult patients who present with constipation, anemia, 3- to 5-day intervals can occur. Some people with im- anorexia, and weight loss are at high suspicion for paction have continuous diarrhea-like passage of stools colorectal cancer. Stools can be of third of people with colon cancer; diarrhea is more small caliber, sometimes described as toothpaste-like. Onset is recent, and there can be progressive On rectal examination, large quantities of hard feces narrowing of stool caliber. The exter- unprepped barium hard or lumpy stools, a sensation of nal sphincter is intact. Retrieved from tion in adults: A systematic review,Am J Gastroenterol100:1605, 2005. Walia R: Recent advances in chronic constipation, Current Opinion Coughlin E: Assessment and management of pediatric constipation Pediatr 21:645, 2009. Cough occurs as foreign body aspiration with occlusion of airway, when inspiration is followed by an explosive expira- severe asthma, escalating heart failure, or pneumonia. Cough can be characterized by the following three The refex stimulation follows the vagus nerve to categories of duration: (1) acute, less than 3 weeks; the “cough center,” which is located in the medulla (2) subacute, lasting 3 to 8 weeks; and (3) chronic, last- oblongata of the brainstem. A cough of recent onset is most locations can be stimulated and initiate the cough often the result of viral or bacterial infection in the re- refex, including the pleura, pericardium, ear canals, spiratory system. Keep ered as a possible cause of cough in both adults and in mind, however, that a cough in a patient in acute children. There is a mismatch between patient expectations and reality, that antibiotics helped is reinforced. Comparing patients’ expectations with data from a systematic review of the literature, Ann Fam Med 11: 5-13, 2011. First, the offending organism invades the epi- caused by a foreign body or the effects of acute asthma. Stimulation sputum, possible weight gain with swollen feet and of cholinergic nerves in the nose and upper respiratory ankles, and often a history of heart disease. Cardiac tract leads to increased mucus production (rhinorrhea) failure of any kind results in decreased lung compli- and occasionally to bronchoconstriction, which causes ance and cough. It is hypothesized that cellular damage to the nasopharynx is probably the cause of a sore and History of Asthma scratchy throat. Acute exacerbation of asthma is characterized by Runny nose with cough and mild fever, followed by a an irritating nonproductive cough that can progress persistent cough, clear to off-white mucus that is greater to tachypnea, dyspnea, wheezing, grunting, cyanosis, in the morning and lasts more than 1 week, suggests fatigue, and fnally respiratory and cardiac failure.
First generic extra super levitra 100 mg erectile dysfunction caused by herpes, retrograde atrial activation is normal (concentric) because it occurs retrogradely up the septum order extra super levitra discount erectile dysfunction numbness. In general cheap 100mg extra super levitra mastercard erectile dysfunction at 21, termination occurs in the anterograde direction, so the last retrograde P wave fails to conduct to the ventricle. Diagnosis of Accessory Pathways Diagnosis can be made by demonstrating that during ventricular pacing, premature ventricular stimulation activates the atria before retrograde depolarization of the His bundle, thus indicating that the impulse reached the atria before it depolarized the His bundle and therefore must have traveled a different pathway. Also, if the ventricles can be stimulated prematurely during tachycardia at a time when the His bundle is refractory, and the impulse still conducts to the atrium, the retrograde propagation traveled to the atrium over a pathway other than the bundle of His (see Fig. Most of these accessory pathways are located between the left ventricle and left atrium or in the posteroseptal area, less often between the right ventricle and right atrium. Syncope can occur because the rapid ventricular rate fails to provide adequate cerebral circulation or because the tachyarrhythmia depresses the sinus pacemaker and causes a period of asystole when the tachyarrhythmia terminates. Physical examination reveals an unvarying, regular ventricular rhythm, with constant intensity of the first heart sound and blood pressure. Jugular venous pressure can be elevated (large A wave), but the waveform generally remains constant. It is necessary to achieve block of a single impulse from the atrium to the ventricle or from the ventricle to the atrium. However, in some circumstances, such as catecholamine stimulation, anterograde conduction can occur in the apparently concealed accessory pathway. Termed accessory atrioventricular pathways or connections, they are responsible for the most common variety of preexcitation. The term syndrome is attached to this disorder when tachyarrhythmias occur as a result of the accessory pathway. The negative delta wave in V with sharp transition to an upright delta wave in V pinpoints it to the right1 2 posteroseptal area. The predominantly negative delta wave in V and the axis more leftward than in 1 A indicate the presence of a right free wall accessory pathway. Various other anatomic substrates exist and provide the basis for different electrocardiographic manifestations of several variations of preexcitation syndrome (Table 37. D, Fasciculoventricular connections, which are not thought to play an important role in the genesis of tachycardias. Maximum preexcitation results in ventricular activation over the accessory pathway, and the His bundle is activated retrogradely. During reciprocating tachycardia, anterograde conduction occurs over the accessory pathway and retrograde conduction over the normal pathway. Nodoventricular accessory connection: a misnomer or a structural/functional spectrum? This pattern of preexcitation can also result from atriofascicular accessory pathways. After a long course, the distal portion of these fibers, which conducts rapidly, inserts into the distal right bundle branch or the apical region of the right ventricle. No preexcitation is generally apparent during sinus rhythm, but it can be exposed by premature or rapid right atrial stimulation. The delta wave represents ventricular activation from input over the accessory pathway. The extent of the contribution to ventricular depolarization by the wavefronts over each route depends on their relative activation times. Such a transformation occurred repeatedly in this patient and was associated with quickening of the ventricular rate. Pacing the atrium at rapid rates, at premature intervals, or from a site close to the atrial insertion of the accessory pathway accentuates the anomalous activation of the ventricles and shortens the H-V interval even more (His activation may become buried in the ventricular electrogram, as shown in Fig. T wave abnormalities can occur after the disappearance of preexcitation, with orientation of the T wave according to the site of preexcitation (T wave memory). D, Orthodromic tachycardia with a slowly conducting accessory pathway (arrowhead). In both tachycardias the accessory pathway is an obligatory part of the reentrant circuit. Usually, a posteroseptal accessory pathway (most often right ventricle but other locations as well) that conducts very slowly, possibly because of a long and tortuous route, appears to be responsible. Although anterograde conduction over this pathway has been demonstrated, the long anterograde conduction time over the accessory pathway usually prevents the electrocardiographic manifestations of accessory pathway conduction during sinus rhythm. Premature ventricular stimulation (arrowhead) occurs at a time when the His bundle is refractory from depolarization during the tachycardia (second labeled H). The rhythm strips below (lead I) indicate that whenever a nonconducted P wave occurs, the tachycardia always terminates, only to begin again after several sinus beats. Recognition of Accessory Pathways When retrograde atrial activation during tachycardia occurs over an accessory pathway that connects the left atrium to the left ventricle, the earliest retrograde activity is recorded from a left atrial electrode usually positioned in the coronary sinus (see Fig. When retrograde atrial activation during tachycardia occurs over an accessory pathway that connects the right ventricle to the right atrium, the earliest retrograde atrial activity is generally recorded from a lateral right atrial electrode. Participation of a septal accessory pathway creates the earliest retrograde atrial activation in the low right portion of the atrium situated near the septum, anterior or posterior, depending on the insertion site. Recording electrical activity directly from the accessory pathway obviously provides precise localization. Some accessory pathways can conduct anterogradely only; more often, pathways conduct retrogradely only. If the pathway conducts only anterogradely, it cannot participate in the usual form of reciprocating tachycardia (see Fig. Some data suggest that the accessory pathway demonstrates automatic activity, which could conceivably be responsible for some cases of tachycardia. Clinical Features The reported incidence of preexcitation syndrome depends in large measure on the population studied and varies from 0. Left free wall accessory pathways were most common, followed in frequency by posteroseptal, right free wall, and anteroseptal locations. The prevalence is higher in men and decreases with age, apparently because of loss of preexcitation. Most adults with preexcitation syndrome have normal hearts, although various acquired and congenital cardiac defects have been reported, including Ebstein anomaly, mitral valve prolapse, and cardiomyopathies. Patients with Ebstein anomaly often have multiple right- sided accessory pathways, either in the posterior septum or in the posterolateral wall, with preexcitation localized to the atrialized ventricle (see Chapter 75). For most patients with recurrent tachycardia, the prognosis is good, but sudden death does occur rarely, with an estimated frequency of 14 0. Before invasive testing, patients and parents/guardians should undergo counseling to discuss the risks and benefits of proceeding with invasive ‡ studies, the risks associated with observation only, and risks related to the medication strategy. Relatives of patients with preexcitation, particularly those with multiple pathways, have an increased prevalence of preexcitation, thus suggesting a hereditary mode of acquisition. Some children and adults can lose their tendency for the development of tachyarrhythmias as they grow older, possibly as a result of fibrotic or other changes at the site of insertion of the accessory pathway. Tachycardia still present after 5 years of age persists in 75% of patients, regardless of the location of the accessory pathway. These approaches are relatively specific but not very sensitive, with low positive predictive accuracy. Patients with asymptomatic intermittent ventricular preexcitation do not require further 14 evaluation or therapy and should simply be observed.
G. Yokian. California State University, Dominguez Hills.