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Updated: 2017-07-07T22:19:35.634+03:00

 



Early Treatment of Ocular Hypertension May Reduce Risk for Glaucoma

2011-02-12T06:14:29.756+02:00

March 16, 2010 — Early treatment of ocular hypertension appears to reduce the risk for the development of glaucoma, especially in individuals at the highest risk, according to the results of a randomized controlled trial reported in the March issue of Archives of Ophthalmology."Elevated intraocular pressure (IOP) (ocular hypertension [OHT]) is a leading risk factor for the development of primary open angle glaucoma (POAG) and the only modifiable risk factor at present," write Michael A. Kass, MD, from Washington University School of Medicine in St. Louis, Missouri, and colleagues for the Ocular Hypertension Treatment Study (OHTS) Group. "It is estimated that 4% to 7% of the US population older than 40 years has OHT. There is substantial controversy on how to manage this large group of individuals who are at higher risk of developing glaucoma than the general population."The goal of the study was to compare the safety and efficacy of earlier vs later treatment in reducing the risk for POAG in 1636 individuals with ocular hypertension, with baseline IOP ranging from 24 to 32 mm Hg in 1 eye and 21 to 32 mm Hg in the other eye. Participants were randomly assigned to observation or to receive topical ocular hypotensive medication. In the medication group, median duration of treatment was 13.0 years, whereas the observation group had a median duration of 7.5 years without treatment and then received medication for a median of 5.5 years.To evaluate whether delaying treatment was associated with any harms, the investigators compared the cumulative proportion of participants who went on to have POAG in the original observation group and in the original medication group at a median follow-up of 13 years.Overall, this proportion was 0.22 in the original observation group (95% confidence interval [CI], 0.19 - 0.25) vs 0.16 (95% CI, 0.13 - 0.19) in the original medication group (P =. 009), or a 27% reduction in glaucoma risk associated with early treatment. For participants at the highest tertile of baseline risk for the development of POAG, based on age, corneal thickness, and baseline IOP, the cumulative proportion of participants who went on to have POAG was 0.40 (95% CI, 0.33 - 0.46) and 0.28 (95% CI, 0.22 - 0.34), respectively."There was little evidence of increased adverse events associated with medication," the study authors write. "Absolute reduction was greatest among participants at the highest baseline risk of developing POAG. Individuals at high risk of developing POAG may benefit from more frequent examinations and early preventive treatment."Limitations of the OHTS study include choice of a target IOP reduction of 20% from baseline, design not that of an epidemiologic study, use of very high thresholds for diagnosing POAG, and use of a convenience sample vs a population-based sample."We believe individualized assessment of the risk of developing POAG will be useful to patients and clinicians for deciding on the frequency of examinations and tests as well as the possible administration of preventive treatment," the study authors write. "Clinicians need to consider the patient's age, health status, life expectancy, and personal preferences when making such decisions. Ultimately, the full extent of the penalty for delaying treatment will require longer follow-up to ascertain the incidence and degree of visual impairment by randomization group."In an accompanying editorial, Alfred Sommer, MD, MHS, from Bloomberg School of Public Health at Johns Hopkins University in Baltimore, Maryland, notes that clinicians should consider whether treating patients with IOP might do more harm than good."In the end, the physician is stuck with the persistent problem of whom to treat and whom to watch," Dr. Sommer writes. "The fascinating article by Kass et al provides interesting insights as to many of the issues at stake, but offers little definitive information to guide us. It probably still makes sense that young patients with lots of high risk factors should receive prophylaxis, while elderly patients with few risk factors should not.[...]



Unintentional Therapeutic Errors Involving Insulin in the Ambulatory Setting Reported to Poison Centers

2011-02-10T18:56:52.267+02:00

Background: Adverse drug events in the ambulatory care setting are not uncommon and can cause significant morbidity. Little research has been published on the management of adverse drug events involving insulin in the outpatient setting.Objective: To analyze data on patients with unintentional therapeutic errors involving insulin managed by 9 regional poison control centers.Methods: A retrospective search was performed for all records involving insulin at 9 poison centers, covering the population of 4 states for the years 2000–2009. A subgroup of the study population was selected with a reason for exposure of "unintentional—therapeutic error."Results: There were 3819 insulin exposures reported, with an increase in the annual incidence of insulin exposures of 279% (from 170 to 645 patients/year) and a mean annual increase of 18%. Of the insulin exposures, 2584 were unintentional therapeutic errors (68%). The percentage of all insulin exposures that were unintentional therapeutic errors increased progressively, from 41% to 78%. There was a 495% increase in annual incidence of unintentional therapeutic errors involving insulin, with a mean annual increase of 28%. Unintentional therapeutic errors involving insulin occurred primarily in adults >40 years (73%), with 63% occurring in women. There was a pronounced increase in unintentional therapeutic errors involving insulin in the later evening hours, with 71% occurring between 1800 and 2400 and reaching a peak at 2200. The majority (n = 1803; 70%) of patients were managed in a non–health-care facility location, primarily their own residence.Conclusions: This is the first report of an increasing trend of insulin-related unintentional therapeutic errors in the ambulatory setting. Our study highlights a number of striking features, including: (1) a consistent and dramatic increase of unintentional therapeutic errors involving insulin over the 10-year period, (2) a high incidence of unintentional therapeutic errors involving insulin in the late evening hours, and (3) a high incidence of unintentional therapeutic errors involving insulin involving adults >40 years and females. With their 24/7 availability, poison centers appear to be an increasingly important resource for patients experiencing unintentional therapeutic errors involving insulin.IntroductionAdverse drug events in the ambulatory care setting are not uncommon and can cause significant morbidity.[1–4]Insulin is one of the leading medications involved in adverse drug events leading to an emergency department visit, especially in older adults.[2] However, the published data on insulin adverse drug events have focused primarily on the hospital setting.[1–4] There is a lack of information on the epidemiology of insulin-associated adverse drug events in the ambulatory care or non–hospital-based setting. One study of a poisons unit in Germany found that 5% of insulin overdoses were accidental, and 90% of the cases were intentional suicidal insulin overdose, with all inquiries coming from the physician caring for the patient, suggesting these cases were not being managed in the ambulatory setting.[5]In the US, poison control centers are able to manage the majority of their patients in the ambulatory care setting, often reducing the need for an unnecessary emergency department visit. Poison control centers manage more than 200,000 adverse drug events annually, with 88% of these patients managed outside of the hospital setting.[3,7] The real-time database of these centers would be a rich source of information on insulin adverse drug events in the ambulatory care setting. To date, no information has been published evaluating insulin adverse drug events in this setting. The objective of this study was to delineate characteristics and outcomes of unintentional therapeutic errors involving insulin, with a focus on cases in the ambulatory care setting.[...]



I am back!

2011-02-10T18:47:21.789+02:00

Gone for few years. I am back to continue blogging :D



Foreign Body Removal, Rectum

2008-10-19T23:45:39.972+03:00

Anorectal foreign bodies are usually inserted transanally for sexual or medicinal purposes. Rectal foreign bodies may also be observed with body packing or stuffing or after prior oral ingestion of the object. Anorectal foreign bodies are more common in men than in women.

Rectal foreign bodies may include such objects as bottles, vibrators, fruit, vegetables, and balls. Cylindrical objects are common. In addition, thermometers may accidentally break while a rectal temperature is being obtained.

Be aware that patients have usually made multiple attempts to remove the object prior to presentation in the emergency department. Patients may create unusual stories to explain how the object became lodged in the rectum.

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2008-10-19T12:02:10.922+03:00

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Astrocytoma

2008-10-05T22:04:45.150+03:00

BackgroundAstrocytomas are CNS neoplasms in which the predominant cell type is derived from an immortalized astrocyte. Two classes of astrocytic tumors are recognized—those with narrow zones of infiltration (eg, pilocytic astrocytoma, subependymal giant cell astrocytoma, pleomorphic xanthoastrocytoma) and those with diffuse zones of infiltration (eg, low-grade astrocytoma, anaplastic astrocytoma, glioblastoma). Members of the latter group share various features, including the ability to arise at any site in the CNS, with a preference for the cerebral hemispheres; clinical presentation usually in adults; heterogeneous histopathological properties and biological behavior; diffuse infiltration of contiguous and distant CNS structures, regardless of histological stage; and an intrinsic tendency to progress to more advanced grades.Numerous grading schemes based on histopathologic characteristics have been devised, including the Bailey and Cushing grading system, Kernohan grades I-IV, World Health Organization (WHO) grades I-IV, and St. Anne/Mayo grades 1-4. Regions of a tumor demonstrating the greatest degree of anaplasia are used to determine the histologic grade of the tumor. This practice is based on the assumption that the areas of greatest anaplasia determine disease progression.This chapter focuses on the widely accepted WHO grading scheme that relies on assessments of nuclear atypia, mitotic activity, cellularity, vascular proliferation, and necrosis. WHO grade I corresponds to pilocytic astrocytoma, WHO grade II corresponds to low-grade (diffuse) astrocytoma, WHO grade III corresponds to anaplastic astrocytoma, and WHO grade IV corresponds to glioblastoma multiforme (GBM). This article is confined to low-grade and anaplastic astrocytomas. GBM and pilocytic astrocytoma are not discussed in this chapter (for more information, see Glioblastoma Multiforme).PathophysiologyRegional effects of astrocytomas include compression, invasion, and destruction of brain parenchyma. Arterial and venous hypoxia, competition for nutrients, release of metabolic end products (eg, free radicals, altered electrolytes, neurotransmitters), and release and recruitment of cellular mediators (eg, cytokines) disrupt normal parenchymal function. Elevated intracranial pressure (ICP) attributable to direct mass effect, increased blood volume, or increased cerebrospinal fluid (CSF) volume may mediate secondary clinical sequelae. Neurological signs and symptoms attributable to astrocytomas result from perturbation of CNS function. Focal neurological deficits (eg, weakness, paralysis, sensory deficits, cranial nerve palsies) and seizures of various characteristics may permit localization of lesions.Infiltrating low-grade astrocytomas grow slowly compared to their malignant counterparts. Doubling time for low-grade astrocytomas is estimated at 4 times that of anaplastic astrocytomas. Several years often intervene between the initial symptoms and the establishment of a diagnosis of low-grade astrocytoma. One recent series estimated the interval to be approximately 3.5 years. The clinical course is marked by a gradual deterioration in one half of cases, a stepwise decline in one third of cases, and a sudden deterioration in 15% of cases. Seizures, often generalized, are the initial presenting symptom in about one half of patients with low-grade astrocytoma.For patients with anaplastic astrocytomas, the growth rate and interval between onset of symptoms and diagnosis is intermediate between low-grade astrocytomas and glioblastomas. Although highly variable, a mean interval of approximately 1.5-2 years between onset of symptoms and diagnosis frequently is reported. Compared to low-grade lesions, seizures are less common among patients with anaplastic astrocytomas. Initial presenting symptoms most commonly are headache, depressed mental status, and focal neurological deficits.Mortality/MorbidityMorbidity and mortality, as[...]



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2008-09-08T16:43:12.983+03:00

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2008-09-03T19:57:48.658+03:00

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2008-09-01T15:30:32.616+03:00

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2008-08-09T15:44:28.128+03:00

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Sexual and Gender Identity Disorders

2008-10-05T22:05:26.540+03:00

History The study of sexual deviancy began just before the turn of the 20th century as the taboo of discussing sexuality was beginning to lift. Early pioneers included Richard von Kraff-Ebing, Albert Moll, August Forel, Iwan Bloch, Magnus Hirschfield, Havelock Ellis, and Sigmund Freud. Their work was not well accepted, and they were regarded with disdain.Several psychiatric concepts were prominent at this time. One of them was a constitutional predisposition of unknown origin called degeneration, which refers to an innate neurologic weakness that is transmitted with increased severity to future generations and produces deviations from the norm. Masturbation was blamed for a list of diseases including insanity, suicide, self-mutilation, and tuberculosis. The law of association of ideas suggests that when sex and another experience occur, one stimulus sets off the other.Ellis worked against the prudish view of sex that existed at the time, and he advocated the decriminalization of homosexuality. Freud wrote on fetishism, masochism, and the theory of perversions. These early investigators of sexual deviation provide an important principal: "Not only must the act be studied, but also the person. The personal roots of deviance spring from an interaction of the individual's biological nature and his early life experiences."Disorders of human behavior remain difficult to understand, identify, and treat. Few data are available, too much of our knowledge is based on speculation and unsupported theory, and societal stereotypes influence our perceptions. Good science-based research remains difficult, and monetary, ethical, and legal concerns complicate such research.PARAPSexual deviation is a term applicable to a subclass of sexual disorders termed paraphilias. Paraphilias are associated with arousal in response to sexual objects or stimuli not associated with normal behavior patterns and that may interfere with the establishment of sexual relationships. In modern classification systems, the term paraphilia is preferable to sexual deviation because it clarifies the essential nature of this group of behaviors (ie, arousal in response to an inappropriate stimulus). The American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR), the prevailing resource for diagnostic criteria of paraphilias, describes the essential feature of paraphilias as recurrent, intense, sexual urges and sexually arousing fantasies generally involving nonhuman objects, the suffering or humiliation of oneself or partner, or children or other nonconsenting persons. The DSM-IV-TR describes 8 of the more commonly observed paraphilias and makes reference to several other examples. People who experience one paraphilia may also experience other paraphilias, although the paraphilia may occur as an isolated event. Commonly, people who manifest paraphilias also exhibit personality disorders, substance abuse problems, or affective disorders.PrevalenceParaphilias are rarely diagnosed in clinical settings. Large commercial markets in paraphiliac pornography and paraphernalia are testaments that prevalence is high. Pedophilia, voyeurism, and exhibitionism are the most commonly observed behaviors in clinics that specialize in paraphilia treatment. Sexual masochism and sexual sadism are much less commonly observed. Approximately half of patients observed in clinics for treatment of paraphilias are married.DifferentialsNonparaphiliacs may describe nonpathological use of sexual fantasies, behaviors, or objects as stimuli for sexual excitement.In patients with mental retardation, paraphilia should be distinguished from dementia, personality change due to general medical condition, substance intoxication, manic episode, or schizophrenia in w[...]



Botulism

2008-08-01T18:04:47.571+03:00

Botulism is an acute neurologic disorder with potentially life-threatening neuroparalysis that is caused by a neurotoxin produced by Clostridium botulinum (CB). The toxin binds irreversibly to the presynaptic membranes of peripheral neuromuscular and autonomic nerve junctions. Toxin binding blocks acetylcholine release, resulting in weakness, flaccid paralysis, and (often) respiratory arrest. Cure occurs following sprouting of new nerve terminals.The 3 main clinical presentations of botulism include infant, food-borne, and wound. Additionally, because of the potency of the toxin, the possibility of botulism as a bioterrorism agent or biological weapon is a great concern.Infant botulism (IB) arises from ingested botulism spores that germinate in the intestine and produce toxin. These spores typically come from bee honey or the environment. Most infants fully recover with supportive treatment; the infant mortality rate is less than 1%. Improperly canned or home-prepared foods are common sources of the toxin that can result in food-borne botulism (FBB). Wound botulism (WB) results from contamination of the wound with toxin-producing CB. FBB and WB occur predominantly in adults and are the focus of this article.CB is an anaerobic gram-positive rod that survives in soil and marine sediment by forming spores. Under anaerobic conditions that permit germination, it synthesizes and releases a potent exotoxin. Microbiologically, the organism stains gram-positive in cultures less than 18 hours old. The organism may stain gram-negative after 18 hours of incubation, potentially complicating attempts at diagnosis. On a molecular weight basis, botulinum toxins are the most potent toxins known.Eight antigenically distinct CB toxins are known, including A, B, C (alpha), C (beta), D, E, F, and G. Each strain of CB is limited to producing a single toxin type. Types A, B, E, and (rarely) F cause human disease. Toxins A and B are the most potent, and the consumption of small amounts of food contaminated with them has resulted in full-blown disease. During the last 20 years, toxin A has been the most frequent cause of food-borne outbreaks; toxins B and E follow in frequency. In 15% of CB outbreaks, the toxin type is not determined. Toxins C and D cause disease in a variety of animals. Type G toxin has been associated with sudden death but not with neuroparalytic illness. It was isolated from autopsy material from 5 patients in Switzerland in 1977.PathophysiologyThe mechanism of action involves toxin-mediated blockade of neuromuscular transmission in cholinergic nerve fibers. This is accomplished by either inhibiting acetylcholine release at the presynaptic clefts of the myoneural junctions or by binding acetylcholine itself. Toxins are absorbed from the stomach and small intestine where they are not denatured by digestive enzymes. Subsequently, they are hematogenously disseminated and block neuromuscular transmission in cholinergic nerve fibers. The nervous, gastrointestinal, endocrine, and metabolic systems are predominantly affected. Because the motor end plate responds to acetylcholine, botulinum toxin ingestion results in hypotonia that manifests as descending symmetric flaccid paralysis and is usually associated with gastrointestinal symptoms of nausea, vomiting, and diarrhea. Cranial nerves are affected early in the course of disease. Later complications include paralytic ileus, severe constipation, and urinary retention.WB results when wounds are contaminated with CB spores. It has occurred (1) after traumatic injury that involved soil contamination, (2) among injection drug users, particularly those who use black-tar heroin, and (3) after cesarean delivery. The wound may appear deceptively benign. Traumatized and devitalized tissue provide[...]



Diabetes Mellitus, Type 1

2008-08-01T18:04:24.445+03:00

Diabetes mellitus (DM) is a multisystem disease with both biochemical and anatomical consequences. It is a chronic disease of carbohydrate, fat, and protein metabolism caused by the lack of insulin. In type 1 diabetes, insulin is functionally absent because of the destruction of the beta cells of the pancreas. Type 1 DM occurs most commonly in juveniles but can occur in adults, especially in those in their late 30s and early 40s. Unlike people with type 2 DM, those with type 1 DM generally are not obese and may present initially with diabetic ketoacidosis (DKA).PathophysiologyType 1 DM is a catabolic disorder in which circulating insulin is very low or absent, plasma glucagon is elevated, and the pancreatic beta cells fail to respond to all insulin-secretory stimuli. Patients need exogenous insulin to reverse this catabolic condition, prevent ketosis, decrease hyperglucagonemia, and normalize lipid and protein metabolism. Type 1 DM is an autoimmune disease. The pancreas shows lymphocytic infiltration and destruction of insulin-secreting cells of the islets of Langerhans, causing insulin deficiency. Approximately 85% of patients have circulating islet cell antibodies, and the majority also have detectable anti-insulin antibodies before receiving insulin therapy. Most islet cell antibodies are directed against glutamic acid decarboxylase (GAD) within pancreatic B cells.One theory regarding the etiology of type 1 DM is that it results from damage to pancreatic beta cells from an infectious or environmental agent. It triggers the immune system in a genetically susceptible individual to develop an autoimmune response against altered pancreatic beta cell antigens or molecules in beta cells that resemble a viral protein. Currently, autoimmunity is considered the major factor in the pathophysiology of type 1 DM. Prevalence is increased in patients with other autoimmune diseases, such as Graves disease, Hashimoto thyroiditis, and Addison disease. Approximately 95% of patients with type 1 DM have either human leukocyte antigen (HLA)-DR3 or HLA-DR4. HLA-DQs are considered specific markers of type 1 DM susceptibility.Environmental agents that have been hypothesized to induce an attack on beta cell function include viruses (eg, mumps, rubella, Coxsackie B4), toxic chemicals, exposure to cow's milk in infancy, and cytotoxins.Recent evidence suggests a role for vitamin D in the pathogenesis and prevention of diabetes mellitus.FrequencyUnited StatesRoughly 5-15% of all cases of diabetes are type 1 DM. It is the most common metabolic disease of childhood, with a yearly incidence of 15 cases per 100,000 people younger than 18 years. Approximately 1 million Americans have type 1 DM, and physicians diagnose 10,000 new cases every year. According to the American Diabetes Association, there are 20.8 million children and adults in the United States, or 7% of the population, who have diabetes. While an estimated 14.6 million have been diagnosed, unfortunately, 6.2 million people (or nearly one-third) are undiagnosed. Fifty-four million people are prediabetes status. In people younger than 20 years, 176,500 cases, or 0.22% of all people in this age group, have diabetes. About one in every 400-600 children and adolescents has type 1 DM. Two million adolescents (or 1 in 6 overweight adolescents) aged 12-19 years have prediabetes status. In people aged 20 years or older, 1.5 million new cases of diabetes were diagnosed in 2005.InternationalScandinavia has the highest prevalence rates for type 1 DM (ie, approximately 20% of the total number of people with DM), while China and Japan have the lowest prevalence rates, with less than 1% of all people with diabetes. Some of these differences may relate to definitional issues and th[...]



Diabetes Mellitus, Type 1 (pedia)

2008-07-31T17:46:39.686+03:00

Diabetes mellitus (DM) is a chronic metabolic disorder caused by an absolute or relative deficiency of insulin, an anabolic hormone. Insulin is produced by the beta cells of the islets of Langerhans located in the pancreas, and the absence, destruction, or other loss of these cells results in type 1 diabetes (insulin-dependent diabetes mellitus [IDDM]). Most children with diabetes have IDDM and a lifetime dependence on exogenous insulin.Type 2 diabetes (non–insulin-dependent diabetes mellitus [NIDDM]) is a heterogeneous disorder. Most patients with NIDDM have insulin resistance, and their beta cells lack the ability to overcome this resistance. Although this form of diabetes was previously uncommon in children, in some, countries 20% or more of new patients with diabetes in childhood and adolescence have NIDDM, a change associated with increased rates of obesity. Other patients may have inherited disorders of insulin release leading to maturity onset diabetes of the young (MODY).This chapter addresses only IDDM.PathophysiologyInsulin is essential to process carbohydrates, fat, and protein. Insulin reduces blood glucose levels by allowing glucose to enter muscle cells and by stimulating the conversion of glucose to glycogen (glycogenesis) as a carbohydrate store. Insulin also inhibits the release of stored glucose from liver glycogen (glycogenolysis) and slows the breakdown of fat to triglycerides, free fatty acids, and ketones. It also stimulates fat storage. Additionally, insulin inhibits the breakdown of protein and fat for glucose production (gluconeogenesis) in both liver and kidneys. Hyperglycemia (ie, random blood glucose concentration more than 200 mg/dL or 11 mmol/L) results when insulin deficiency leads to uninhibited gluconeogenesis and prevents the use and storage of circulating glucose. The kidneys cannot reabsorb the excess glucose load, causing glycosuria, osmotic diuresis, thirst, and dehydration. Increased fat and protein breakdown leads to ketone production and weight loss. Without insulin, a child with IDDM wastes away and eventually dies from diabetic ketoacidosis (DKA).An excess of insulin prevents the release of glucose into the circulation and results in hypoglycemia (blood glucose concentrations of [...]



Mesenteric Ischemia

2008-07-30T15:00:01.599+03:00

Mesenteric ischemia is a relatively rare disorder seen in the emergency department (ED); however, it is an important diagnosis to make because of its high mortality rate. Vague and nonspecific clinical findings and limitations of diagnostic studies make the diagnosis a significant challenge. Moreover, delays in diagnosis lead to increased mortality rates. Despite recent advances in diagnosis and treatment, mortality rates continue to remain high.PathophysiologyMesenteric ischemia is caused by decreased intestinal blood flow that can be caused by a number of mechanisms. Decreased intestinal blood flow results in ischemia and subsequent reperfusion damage at the cellular level that may progress to the development of mucosal injury, tissue necrosis, and metabolic acidosis.The blood supply to the intestine is derived predominantly from 3 major gastrointestinal arteries that arise from the abdominal aorta: the celiac axis, the superior mesenteric artery (SMA), and the inferior mesenteric artery (IMA). The intestine has significant collateral circulation at all levels that allows for some protection from ischemia and is able to compensate for approximately a 75% acute reduction in mesenteric blood flow for up to 12 hours, without substantial injury.The pathophysiology of intestinal ischemia can be divided into arterial and venous etiologies and acute and chronic ischemia. The vast majority of cases are secondary to arterial causes. All diseases and conditions that affect arteries, including atherosclerosis, arteritis, aneurysms, arterial infections, dissections, arterial emboli, and thrombosis, are reported to occur in the intestinal arteries.Acute mesenteric ischemia (AMI) can be further divided into embolic, thrombotic, or nonocclusive causes.Arterial embolism Arterial embolism accounts for approximately one third of acute cases of AMI. Emboli to the mesenteric arteries are usually from a dislodged cardiac thrombus. The SMA is most commonly affected with the IMA rarely affected due to its small caliber.Arterial thrombosis Arterial thrombosis accounts for approximately one third of acute cases of AMI. It is usually due to acute worsening of ischemia in patients who have preexisting atherosclerosis of the mesenteric arteries. Thrombosis often involves at least 2 of the major splanchnic vessels.Nonocclusive etiology Nonocclusive etiology accounts for approximately one third of acute cases of AMI. The primary mechanism is severe and prolonged intestinal vasoconstriction. The most common setting is severe systemic illness with systemic shock usually secondary to reduced cardiac output. Intestinal vasospasm has also been seen to occur in cocaine ingestion, ergot poisoning, digoxin use, and with alpha-adrenergic agonists. A small proportion of cases are from venous thrombosis, seen mostly in patients with hypercoagulable states. Venous thrombosis of the visceral vessels may precipitate an acute ischemic event as compromised venous return leads to interstitial swelling of the bowel wall, with subsequent impedance of arterial flow and eventual tissue necrosis.Chronic mesenteric ischemia (CMI) usually results from long-standing atherosclerotic disease of 2 or more mesenteric vessels. Other nonatheromatous causes of CMI include the vasculitides such as Takayasu arteritis. Symptoms are caused by the gradual reduction in blood flow to the intestine that occurs during eating since total blood flow to the intestine can increase by 15% during meals.FrequencyUnited StatesAMI is involved in up to 0.1% of all hospital admissions, although this number is likely to rise as the population ages.Mortality/MorbidityMortality rates are high and range from 60-100% depending o[...]



Aortic Stenosis

2008-07-30T12:00:01.250+03:00

Aortic stenosis (AS) is the obstruction of blood flow across the aortic valve. AS has several etiologies: congenital unicuspid or bicuspid valve, rheumatic fever, and degenerative calcific changes of the valve.

Pathophysiology
When the aortic valve becomes stenotic, resistance to systolic ejection occurs and a systolic pressure gradient develops between the left ventricle and the aorta. Stenotic aortic valves have a decreased aperture that leads to a progressive increase in left ventricular systolic pressure. This leads to pressure overload in the left ventricle, which, over time, causes an increase in ventricular wall thickness (ie, concentric hypertrophy). At this stage, the chamber is not dilated and ventricular function is preserved, although diastolic compliance may be affected.

Eventually, however, the left ventricle dilates. This, coupled with a decrease in compliance, is associated with an increase in left ventricular end-diastolic pressure, which is increased further by a rise in atrial systolic pressure. A sustained pressure overload eventually leads to myocardial decompensation. The contractility of the myocardium diminishes, which leads to a decrease in cardiac output. The elevated left ventricular end-diastolic pressure causes a corresponding increase in pulmonary capillary arterial pressures and a decrease in ejection fraction and cardiac output. Ultimately, congestive heart failure (CHF) develops.

Frequency
United States
Aortic stenosis is a relatively common congenital cardiac defect. Incidence is 4 in 1000 live births.


Mortality/Morbidity
Sudden cardiac death occurs in 3-5% of patients with AS. Adults with AS have a 9% mortality rate per year. Once symptoms develop, the incidence of sudden death increases to 15-20%, with average survival duration of less than 5 years. Patients with exertional angina or syncope survive an average of 3 years. After the development of left ventricular failure, life expectancy is slightly greater than 1 year.

Sex
Among children, 75% of cases of AS are in males.

Age
AS usually is not detected until individuals are school aged. AS exists in up to 2% of those who are younger than 70 years. The etiology of AS in those aged 30-70 years can be rheumatic disease or calcification of a congenital bicuspid valve. In those older than 70 years, degenerative calcification is the primary cause of AS. Among people older than 75 years, 3% have critical AS.


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ART

2008-07-30T07:12:45.737+03:00

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Angina Pectoris

2008-07-30T07:17:23.922+03:00

Angina pectoris (AP) represents the clinical syndrome occurring when myocardial oxygen demand exceeds supply. The term is derived from Latin; the literal meaning is "the choking of the chest;" angere, meaning "to choke" and pectus, meaning "chest." The first English-written account of recurrent angina pectoris was by English nobleman Edward Hyde, Earl of Clarendon. He described his father as having, with exertion, "a pain in the left arm…so much that the torment made him pale".1 The first description of angina as a medical disorder came from William Heberden. Heberden, a prodigious physician, made many noteworthy contributions to medicine during his career. He presented his observations on "dolor pectoris" to the Royal College of Physicians in 1768. Much of his classic description retains its validity today.2 Angina pectoris has a wide range of clinical expressions. The symptoms most often associated to angina pectoris are substernal chest pressure or tightening, frequently with radiating pain to the arms, shoulders, or jaw. The symptoms may also be associated with shortness of breath, nausea, or diaphoresis. Symptoms stem from inadequate oxygen delivery to myocardial tissue. No definitive diagnostic tools that capture all patients with angina pectoris exist. This, combined with its varied clinical expression, makes angina pectoris a distinct clinical challenge to the emergency physician. The disease state can manifest itself in a variety of forms:Stable angina pectoris is classified as a reproducible pattern of anginal symptoms that occur during states of increased exertion.Unstable angina pectoris (UA) manifests either as an increasing frequency of symptoms or as symptoms occurring at rest.Prinzmetal angina or variant angina occurs as a result of transient coronary artery spasms. These spasms can occur either at rest or with exertion. Unlike stable or unstable angina, no pathological plaque or deposition is present within the coronary arteries that elicits the presentation. On angiography, the coronary arteries are normal in appearance.Cardiac syndrome X occurs when a patient has all of the symptoms of angina pectoris without coronary artery disease or spasm.PathophysiologyThe past 2 decades has greatly expanded our overall understanding of the pathophysiology of myocardial ischemic syndromes. The primary dysfunction in angina pectoris is decreased oxygen delivery to myocardial muscle cells. The 2 predominant mechanisms by which delivery is impaired appear to be coronary artery narrowing and endothelial dysfunction. Any other mechanism that affects oxygen delivery can also precipitate symptoms. Extracardiac causes of angina include, but are by no means limited to, anemia, hypoxia, hypotension, bradycardia, carbon monoxide exposure, and inflammatory disorders.3 The end result is a shift to anaerobic metabolism in the myocardial cells. This is followed by a stimulation of pain receptors that innervate the heart. These pain receptors ultimately are referred to afferent pathways, which are carried in multiple nerve roots from C7 through T4. The referred/radiating pain of angina pectoris is believed to occur because these afferent pathways also carry pain fibers from other regions (eg, the arm, neck, and shoulders).Coronary artery narrowingCoronary artery narrowing appears to be the etiology of cardiac ischemia in the preponderance of cases. This has clinical significance when atherosclerotic disease diminishes or halts blood flow through the coronary arterial circulation, interfering with normal laminar blood flow. The significance of even a small change in the dia[...]



Allergic Rhinitis

2008-07-29T16:18:38.293+03:00

Rhinitis is defined as inflammation of the nasal membranes1 and is characterized by a symptom complex that consists of any combination of the following: sneezing, nasal congestion, nasal itching, and rhinorrhea. The eyes, ears, sinuses, and throat can also be involved. Allergic rhinitis is the most common cause of rhinitis. It is an extremely common condition, affecting approximately 20% of the population. While allergic rhinitis is not a life-threatening condition, complications can occur and the condition can significantly impair quality of life, which leads to a number of indirect costs. The total direct and indirect cost of allergic rhinitis was recently estimated to be $5.3 billion per year.PathophysiologyAllergic rhinitis involves inflammation of the mucous membranes of the nose, eyes, eustachian tubes, middle ear, sinuses, and pharynx. The nose invariably is involved, and the other organs are affected in certain individuals. Inflammation of the mucous membranes is characterized by a complex interaction of inflammatory mediators but ultimately is triggered by an immunoglobulin E (IgE)–mediated response to an extrinsic protein.The tendency to develop allergic, or IgE-mediated, reactions to extrinsic allergens (proteins capable of causing an allergic reaction) has a genetic component. In susceptible individuals, exposure to certain foreign proteins leads to allergic sensitization, which is characterized by the production of specific IgE directed against these proteins. This specific IgE coats the surface of mast cells, which are present in the nasal mucosa. When the specific protein (eg, a specific pollen grain) is inhaled into the nose, it can bind to the IgE on the mast cells, leading to immediate and delayed release of a number of mediators.The mediators that are immediately released include histamine, tryptase, chymase, kinins, and heparin. The mast cells quickly synthesize other mediators, including leukotrienes and prostaglandin D2. These mediators, via various interactions, ultimately lead to the symptoms of rhinorrhea (ie, nasal congestion, sneezing, itching, redness, tearing, swelling, ear pressure, postnasal drip). Mucous glands are stimulated, leading to increased secretions. Vascular permeability is increased, leading to plasma exudation. Vasodilation occurs, leading to congestion and pressure. Sensory nerves are stimulated, leading to sneezing and itching. All of these events can occur in minutes; hence, this reaction is called the early, or immediate, phase of the reaction.Over 4-8 hours, these mediators, through a complex interplay of events, lead to the recruitment of other inflammatory cells to the mucosa, such as neutrophils, eosinophils, lymphocytes, and macrophages. This results in continued inflammation, termed the late-phase response. The symptoms of the late-phase response are similar to those of the early phase, but less sneezing and itching and more congestion and mucus production tend to occur. The late phase may persist for hours or days.Systemic effects, including fatigue, sleepiness, and malaise, can occur from the inflammatory response. These symptoms often contribute to impaired quality of life.FrequencyUnited StatesAllergic rhinitis affects approximately 40 million people in the United States. Recent US figures suggest a 20% cumulative prevalence rate.InternationalScandinavian studies have demonstrated a cumulative prevalence rate of 15% in men and 14% in women. The prevalence of allergic rhinitis may vary within and among countries. This may be due to geographic differences in the types and potency o[...]



Cholera

2008-07-29T15:37:21.515+03:00

The word cholera is derived from a Greek term that means "flow of bile." Cholera is caused by Vibrio cholerae, the most feared epidemic diarrheal disease because of its severity. Dehydration and death can occur within hours of infection.Robert Koch discovered V cholerae in 1883 during an outbreak in Egypt. The organism is a comma-shaped, gram-negative aerobic bacillus whose size varies from 1-3 µm in length by 0.5-0.8 µm in diameter. Its antigenic structure consists of a flagellar H antigen and a somatic O antigen. The differentiation of the latter allows for separation into pathogenic and nonpathogenic strains. V cholerae O1 and V cholerae O139 are associated with epidemic cholera. V cholerae O1 is classified into 2 major biotypes: classic and El Tor. Currently, El Tor is the predominant cholera pathogen. Organisms in both biotypes are subdivided into serotypes according to the structure of the O antigen, as follows:Serotype Inaba - O antigens A and C Serotype Ogawa - O antigens A and B Serotype Hikojima - O antigens A, B, and CPathophysiologyThe infectious dose of bacteria required to cause clinical disease varies by the mode of administration. If ingested with water, the infectious dose is 103-106 organisms. When ingested with food, fewer organisms (102-104 organisms) are required to produce disease. The use of antacids, histamine receptor blockers, and proton pump inhibitors increases the risk of cholera infection and predisposes patients to more severe disease as a result of reduced gastric acidity. The same applies to patients with chronic gastritis secondary to Helicobacter pylori infection or those who have undergone a gastrectomy.V cholerae O1 and V cholerae O139 cause clinical disease by producing an enterotoxin that promotes the secretion of fluid and electrolytes into the lumen of the small intestine. The enterotoxin is a protein molecule composed of 5 B subunits and 2 A subunits. The B subunits are responsible for binding to a ganglioside (monosialosyl ganglioside, GM1) receptor located on the surface of the cells that line the intestinal mucosa.The activation of the A1 subunit by adenylate cyclase is responsible for the net increase in cyclic adenosine monophosphate (cAMP). cAMP blocks the absorption of sodium and chloride by the microvilli and promotes the secretion of chloride and water by the crypt cells. The result is watery diarrhea with electrolyte concentrations isotonic to those of plasma.Fluid loss originates in the duodenum and upper jejunum; the ileum is less affected. The colon is usually in a state of absorption because it is relatively insensitive to the toxin. However, the large volume of fluid produced in the upper intestine overwhelms the absorptive capacity of the lower bowel, resulting in severe diarrhea.The enterotoxin acts locally and does not invade the intestinal wall. As a result, few neutrophils are found in the stool.FrequencyUnited StatesAmong the millions of Americans who travel to endemic areas in foreign countries, only 42 imported cases of cholera were reported from 1965-1991. However, in August 1986, 4 cases of cholera were acquired in Louisiana and 1 case was acquired in Florida. These patients were hospitalized with severe diarrhea and had stool cultures that yielded toxigenic V cholerae O1 Inaba. Although the vehicle of transmission was not specifically identified, the patients had consumed seafood within 5 days prior to symptom onset. Toxigenic V cholerae O1 El Tor Inaba appears to have an environmental reservoir on the US Gulf Coast. Sixty-one cases of cholera[...]



Cardiac Cirrhosis

2008-07-16T12:05:00.492+03:00

Background
Cardiac cirrhosis (congestive hepatopathy) includes a spectrum of hepatic derangements that occur in the setting of right-sided heart failure. Clinically, the signs and symptoms of congestive heart failure (CHF) dominate the disorder. Unlike cirrhosis caused by chronic alcohol use or viral hepatitis, the effect of cardiac cirrhosis on overall prognosis is unknown. Because of this, treatment is aimed at managing the patient's underlying heart failure.

Distinguish cardiac cirrhosis from ischemic hepatitis. The latter condition may involve massive hepatocellular necrosis caused by sudden cardiogenic shock or other hemodynamic collapse. Typically, sudden and dramatic serum hepatic transaminase elevations lead to its discovery. Although cardiac cirrhosis and ischemic hepatitis arise from distinct underlying cardiac lesions (right-sided heart failure in the former and left-sided failure in the latter), in clinical practice they may present together.

Despite its name, cardiac cirrhosis rarely satisfies strict pathologic criteria for cirrhosis. The terms congestive hepatopathy and chronic passive liver congestion are more accurate, but the name cardiac cirrhosis has become convention.

Pathophysiology
Decompensated right ventricular or biventricular heart failure causes transmission of elevated central venous pressures directly to the liver via the inferior vena cava and hepatic veins. At a cellular level, venous congestion impedes efficient drainage of sinusoidal blood flow into terminal hepatic venules. Sinusoidal stasis results in accumulation of deoxygenated blood, parenchymal atrophy, necrosis, collagen deposition, and, ultimately, fibrosis.

A separate theory proposes that cardiac cirrhosis is not simply a response to chronically increased pressure and sinusoidal stasis. That intrahepatic vascular lesions are confined to areas of the liver with higher fibrotic burden suggests that cardiac cirrhosis requires a higher grade of vascular obstruction, such as intrahepatic thrombosis, for its development. The theory proposes that thrombosis of sinusoids and terminal hepatic venules propagates to medium-sized hepatic veins and to portal vein branches, resulting in parenchymal extinction and fibrosis.

Frequency
United States
Cardiac cirrhosis rarely occurs in the United States. Its true prevalence is difficult to estimate, since the disease typically remains subclinical and undiagnosed. The incidence of cardiac cirrhosis at autopsy has decreased significantly over the past several decades. This may be due to lower rates of uncorrected rheumatic heart disease and constrictive pericardial disease.

Mortality/Morbidity
The effect of cardiac cirrhosis on mortality and morbidity rates is unknown. The severity of the patient's underlying cardiac disease, which is typically advanced and chronic, is the major determinant of overall outcome.

Sex
Comparative sex data for cardiac cirrhosis do not exist. However, because CHF is more common in men than women in the United States, the same is likely for cardiac cirrhosis.

Age
No published data exist. However, the prevalence of cardiac cirrhosis in the United States, like that of CHF, almost certainly increases with age.

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Adrenal Carcinoma

2008-07-16T12:05:27.828+03:00

Adrenocortical cancers (ACs) are uncommon malignancies that can have protean clinical manifestations. Adrenocortical masses are common; autopsy studies show that approximately 5-15% of the general adult population may have adrenal incidentalomas. Adrenal incidentalomas are biochemically and clinically asymptomatic adrenal masses found incidentally as a result of unrelated imaging investigations such as abdominal CT or MRI scans. Findings from abdominal CT scans suggest that the prevalence rate is 1-5%. Only a small number of adrenal tumors are functional and an even smaller number (approximately 1%) are malignant.
Regardless of size, approximately 1 per 1500 adrenal tumors is malignant. The evaluation of these incidentalomas, therefore, focuses on (1) identifying functional masses and treating them appropriately (including surgical removal); (2) identifying adrenal carcinomas early, with the intent of attempting complete surgical extirpation; and (3) reassuring the patients who do not fit either of these classes and arranging for their subsequent follow-up.
Although the means of identifying ACs from this subpopulation still are controversial, virtually all authorities agree about removing all nonfunctional adrenal tumors larger than or equal to 6 cm because of the significant potential cancer risk. Authorities also generally agree that nonfunctional adrenal tumors (£3 cm) have a very low probability of being adrenal cancer; therefore, they can be removed safely.
The management strategy for adrenal masses larger than 3 cm and less than 6 cm is disputed. Some authorities suggest lowering the threshold for surgical removal of nonfunctional masses from 6 cm to 4-5 cm. Others individualize the follow-up of these patients depending on their clinical status, CT scan characteristics, and age. Particularly important is the fact that these criteria do not apply to children, who generally have smaller ACs. A review of the available data suggests that the incidence rate of malignancy is small Frequency
International
AC tumors are uncommon. The incidence is approximately 0.6-1.67 cases per million persons per year. Some reports suggest an inordinately high frequency (up to 10-fold higher) of cases among children in southern Brazil, for unknown reasons. Overall, AC accounts for 0.02-0.2% of all cancer-related deaths; therefore, it is relatively rare.
Race
AC has no specific racial predilection.
Sex
The female-to-male ratio is approximately 2.5-3:1. Male patients tend to be older and have a worse overall prognosis than female patients. Female patients are more likely than male patients to have an associated endocrine syndrome. Nonfunctional ACs are distributed equally between the sexes.
Age
AC occurs in 2 major peaks: in the first decade of life and again in the fourth to fifth decades. Approximately 75% of the children with AC are younger than 5 years. Functional tumors also are more common in children, while nonfunctional tumors are more common in adults.

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Hydrocephalus

2008-07-16T12:07:10.266+03:00

Hydrocephalus can be defined broadly as a disturbance of formation, flow, or absorption of cerebrospinal fluid (CSF) that leads to an increase in volume occupied by this fluid in the central nervous system (CNS). This condition also could be termed a hydrodynamic disorder of CSF. Acute hydrocephalus occurs over days, subacute over weeks, and chronic over months or years. Conditions such as cerebral atrophy and focal destructive lesions also lead to an abnormal increase of CSF in CNS. In these situations, loss of cerebral tissue leaves a vacant space that is filled passively with CSF. Such conditions are not the result of a hydrodynamic disorder and therefore are not classified as hydrocephalus. An older misnomer used to describe these conditions was hydrocephalus ex vacuo.Normal pressure hydrocephalus (NPH) describes a condition that rarely occurs in patients younger than 60 years. Enlarged ventricles and normal CSF pressure at lumbar puncture (LP) in the absence of papilledema led to the term NPH. However, intermittent intracranial hypertension has been noted during monitoring of patients in whom NPH is suspected, usually at night. The classic Hakim triad of symptoms includes gait apraxia, incontinence, and dementia. Headache is not a typical symptom in NPH.Benign external hydrocephalus is a self-limiting absorption deficiency of infancy and early childhood with raised intracranial pressure (ICP) and enlarged subarachnoid spaces. The ventricles usually are not enlarged significantly, and resolution within 1 year is the rule.Communicating hydrocephalus occurs when full communication exists between the ventricles and subarachnoid space. It is caused by overproduction of CSF (rarely), defective absorption of CSF (most often), or venous drainage insufficiency (occasionally).Noncommunicating hydrocephalus occurs when CSF flow is obstructed within the ventricular system or in its outlets to the arachnoid space, resulting in ventricular/subarachnoid space noncommunication.Obstructive hydrocephalus results from obstruction of the flow of CSF (intraventricular or extraventricular). Most hydrocephalus is obstructive, and the term is used to contrast the hydrocephalus caused by overproduction of CSF.Arrested hydrocephalus is defined as stabilization of known ventricular enlargement, probably secondary to compensatory mechanisms. These patients may decompensate, especially following minor head injuries.PathophysiologyNormal CSF production is 0.20-0.35 mL/min; a majority is produced by the choroid plexus, which is located within the ventricular system, mainly the lateral and fourth ventricles. The capacity of the lateral and third ventricles in a healthy person is 20 mL. Total volume of CSF in an adult is 120 mL.Normal route of CSF from production to clearance is the following: From the choroid plexus, the CSF flows to the lateral ventricle, then to the interventricular foramen of Monro, the third ventricle, the cerebral aqueduct of Sylvius, the fourth ventricle, the 2 lateral foramina of Luschka and 1 medial foramen of Magendie, the subarachnoid space, the arachnoid granulations, the dural sinus, and finally into the venous drainage.ICP rises if production of CSF exceeds absorption. This occurs if CSF is overproduced, resistance to CSF flow is increased, or venous sinus pressure is increased. CSF production falls as ICP rises. Compensation may occur through transventricular absorption of CSF and also by absorption along nerve root sleeves. Te[...]



Treadmill and Pharmacologic Stress Testing

2008-06-27T08:39:01.588+03:00

Cardiovascular exercise stress testing in conjunction with an ECG has been established as one of the focal points in the diagnosis and prognosis of cardiovascular disease, specifically coronary artery disease (CAD).Feil and Seigel first noticed the significance of cardiovascular exercise stress testing in 1928; they reported ST and T changes following exercise in 3 patients with chronic stable angina.1 The following year, Master and Oppenheimer introduced a standardized exercise protocol to assess functional capacity and hemodynamic response.Continued research into causal mechanisms of ST displacement, refinement of exercise protocols, and determination of diagnostic and prognostic exercise variables in clinical patient subsets have continued to evolve since 1929.After the establishment of coronary angiography as a diagnostic tool, the limitation of exercise-induced ST-segment depression as a diagnostic marker for obstructive CAD in patient populations with a low disease prevalence became apparent.IntroductionExercise testing is a cardiovascular stress test using treadmill bicycle exercise with ECG and blood pressure monitoring. Pharmacologic stress testing, established after exercise testing, is a diagnostic procedure in which cardiovascular stress induced by pharmacologic agents is demonstrated in patients with decreased functional capacity or in patients who cannot exercise. Pharmacologic stress testing is used in combination with imaging modalities such as radionuclide imaging and echocardiography.Exercise stress testing, which is now widely available at a relatively low cost, is currently used most frequently to estimate prognosis and determine functional capacity, to assess the probability and extent of coronary disease, and to assess the effects of therapy. Ancillary techniques, such as metabolic gas analysis, radionuclide imaging, and echocardiography, can provide further information that may be needed in selected patients, such as those with moderate or prior risk.Exercise physiologyThe initiation of dynamic exercise results in increases in the ventricular heart rate, stroke volume, and cardiac output due to vagal withdrawal and sympathetic stimulation. Also, alveolar ventilation and venous return increase as a result of sympathetic vasoconstriction. The overall hemodynamic response depends on the amount of muscle mass involved, exercise efficiency, conditioning, and exercise intensity.In the initial phases of exercise in the upright position, cardiac output is increased by an augmentation in stroke volume mediated through the use of the Frank-Starling mechanism and heart rate. The increase in cardiac output in the later phases of exercise is due primarily to an increase in ventricular rate.During strenuous exertion, sympathetic discharge is maximal and parasympathetic stimulation is withdrawn, resulting in autoregulation with generalized vasoconstriction, except in the vital organs (cerebral and coronary circulations).Venous and arterial norepinephrine release from sympathetic postganglionic nerve endings is increased, and epinephrine levels are increased at peak exertion, resulting in an increase in ventricular contractility. As exercise progresses, skeletal muscle blood flow increases; oxygen extraction increases as much as 3-fold; peripheral resistance decreases; and systolic blood pressure (SBP), mean arterial pressure, and pulse pressure usually increase. Diastolic blood pressure (DBP) rem[...]



Cor pulmonale

2008-06-26T08:36:01.097+03:00

Cor pulmonale is defined as an alteration in the structure and function of the right ventricle caused by a primary disorder of the respiratory system. Pulmonary hypertension is the common link between lung dysfunction and the heart in cor pulmonale. Right-sided ventricular disease caused by a primary abnormality of the left side of the heart or congenital heart disease is not considered cor pulmonale, but cor pulmonale can develop secondary to a wide variety of cardiopulmonary disease processes. Although cor pulmonale commonly has a chronic and slowly progressive course, acute onset or worsening cor pulmonale with life-threatening complications can occur.Pathophysiology: Several different pathophysiologic mechanisms can lead to pulmonary hypertension and, subsequently, to cor pulmonale. These pathogenetic mechanisms include (1) pulmonary vasoconstriction due to alveolar hypoxia or blood acidemia; (2) anatomic compromise of the pulmonary vascular bed secondary to lung disorders, eg, emphysema, pulmonary thromboembolism, interstitial lung disease; (3) increased blood viscosity secondary to blood disorders, eg, polycythemia vera, sickle cell disease, macroglobulinemia; and (4) idiopathic primary pulmonary hypertension. The result is increased pulmonary arterial pressure.The right ventricle (RV) is a thin-walled chamber that is more a volume pump than a pressure pump. It adapts better to changing preloads than afterloads. With an increase in afterload, the RV increases systolic pressure to keep the gradient. At a point, further increase in the degree of pulmonary arterial pressure brings significant RV dilation, an increase in RV end-diastolic pressure, and circulatory collapse. A decrease in RV output with a decrease in diastolic left ventricle (LV) volume results in decreased LV output. Since the right coronary artery, which supplies the RV free wall, originates from the aorta, decreased LV output diminishes blood pressure in the aorta and decreases right coronary blood flow. This is a vicious cycle between decreases in LV and RV output.Right ventricular overload is associated with septal displacement toward the left ventricle. Septal displacement, which is seen in echocardiography, can be another factor that decreases LV volume and output in the setting of cor pulmonale and right ventricular enlargement. Several pulmonary diseases cause cor pulmonale, which may involve interstitial and alveolar tissues with a secondary effect on pulmonary vasculature or may primarily involve pulmonary vasculature. Chronic obstructive pulmonary disease (COPD) is the most common cause of cor pulmonale in the United States.Cor pulmonale usually presents chronically, but 2 main conditions can cause acute cor pulmonale: massive pulmonary embolism (more common) and acute respiratory distress syndrome (ARDS). The underlying pathophysiology in massive pulmonary embolism causing cor pulmonale is the sudden increase in pulmonary resistance. In ARDS, 2 factors cause RV overload: the pathologic features of the syndrome itself and mechanical ventilation. Mechanical ventilation, especially higher tidal volume, requires a higher transpulmonary pressure. In chronic cor pulmonale, right ventricular hypertrophy (RVH) generally predominates. In acute cor pulmonale, right ventricular dilatation mainly occurs.Frequency:In the US: Cor pulmonale is estimated to account for 6-7% of all types of adult heart disease in t[...]