Myopathies

Practice Essentials

Myopathy is a muscle disease unrelated to any disorder of innervation or neuromuscular junction. This condition has widely varying etiologies, including congenital or inherited, idiopathic, infectious, metabolic, inflammatory, endocrine, and drug-induced or toxic.

Essential update: Glycine amidinotransferase expression in statin-induced myopathy

Differences in susceptibility to statin-induced myopathy may be associated with genetically determined variation in expression of the glycine amidinotransferase (GATM) gene.[1, 2] In a study of lymphoblastoid cell lines from 480 participants in a clinical trial of simvastatin, Mangravite et al identified 6 expression quantitative trait loci (QTL) that interacted with simvastatin exposure. One of these was rs9806699, a cis-expression quantitative trait locus (eQTL) for the GATM gene; GATM encodes the rate-limiting enzyme in creatine synthesis.[1, 2]

Not only was the GATM locus significantly associated with a reduction in risk for statin-induced myopathy in 2 independent populations (patients carrying the rs9806699 locus vs those who do not carry it), but the investigators also indicated that GATM may act as a functional link between statin-mediated lowering of cholesterol and susceptibility to statin-induced myopathy.[1, 2] These findings led Mangravite et al to suggest that “using a novel cell-based screen for gene-by-treatment effects on transcriptional expression”[2] for selective screening of genetic variations in patients on statins may have the potential to lower the risk of statin-induced myopathy or other adverse effects of these agents.[1, 2]

History

Important information to obtain during the patient’s history includes the following:

Family history: Any periodic paralysis or muscular dystrophy?Personal history: Presence of autoimmune disease, endocrinopathy, renal insufficiency, and/or alcoholism? Previous episodes of severe weakness (eg, postexercise, after exposure to cold [possibly one of periodic paralyses]; post high-carbohydrate meals [familial hypokalemic periodic paralysis]) Medications (eg, steroids, lipid lowering agents, retroviral agents, alcohol, colchicine, pentachlorophenol [PCP], heroin)Occupational and travel history (potential ingestion of barium chloride or carbonate [acute hypokalemic paralysis])Signs and symptoms

The common symptoms of myopathy are muscle weakness, impaired function in activities of daily life, and, rarely, muscle pain and tenderness. Significant muscle pain and tenderness without weakness should prompt consideration of other causes.

General signs and symptoms of myopathy include the following:

Symmetric proximal muscle weaknessMalaise, fatigueDark colored urine (suggests myoglobinuria) and/or feverAbsence of sensory complaints or paresthesias; however, deep tendon reflexes (DTRs) may be diminished/absent in hypokalemic paralysis Very late findings: Atrophy and hyporeflexia (early presence usually implicates neuropathies)Normal level of consciousnessGottron papules in dermatomyositis: Pink-to-violaceous scaly areas over knuckles, elbows, and knees

The acuity of symptom onset may aid in the diagnosis, as follows:

Weakness progressing over hours: Possible toxic etiology or one of episodic paralysesWeakness developing over days: May be an acute dermatomyositis or rhabdomyolysisSymptom development over a period of weeks: May be polymyositis, steroid myopathy, or myopathy resulting from endocrine causes (eg, hyperthyroidism, hypothyroidism)

Indications of which muscle groups are involved include the following symptoms:

Proximal muscle weakness: Difficulty rising from chairs, getting out of the bathtub, climbing stairs, and/or shaving or combing the hair Weakness of distal muscles: Weak grasp, handwriting problems, and walking difficulties, (eg, flapping gait)

See Clinical Presentation for more detail.

Diagnosis

Laboratory testing

The following laboratory tests may be used to evaluate patients with myopathies:

Creatine kinase (CK) levels with isoenzymeslevels of electrolytes, calcium, and magnesiumSerum myoglobin levelsSerum creatinine and blood urea nitrogen levelsUrinalysis: Myoglobinuria indicated by positive urinalysis with few red blood cells on microscopic evaluationComplete blood countErythrocyte sedimentation rateThyroid function testsAspartate aminotransferase levels

Other studies may include the following:

ElectrocardiographyAntinuclear antibody levelsGenetic testingElectromyographyMagnetic resonance imaging (to assess complications or rule out neurologic disease)Muscle biopsy

See Workup for more detail.

Management

The treatment of a myopathy is dependent on its etiology and can range from supportive and symptomatic management to therapy for specific conditions. Such treatments may include the following:

Supportive: Management of airway, breathing, circulation; hydration; intensive care management may be needed in some casesDrug therapyPhysical therapyBracingSurgery

See Treatment for more detail.

NextBackground

Myopathy is a muscle disease unrelated to any disorder of innervation or neuromuscular junction. Etiologies vary widely. The common symptoms are muscle weakness, impaired function in activities of daily life, and, rarely, muscle pain and tenderness. Presence of discolored or dark urine suggests myoglobinuria.

For the emergency physician, it is important to distinguish neurologic from muscular dysfunction. However, in the face of profound weakness, establishing ABCs with attention to airway and aspiration precautions and providing supportive care are indicated while inpatient consultation and detailed studies are performed.

PreviousNextPathophysiology

Most congenital myopathies or inherited myopathies are chronic slowly progressive diseases. The emergency physician rarely attends to a patient specifically to treat congenital myopathy unless acute deterioration occurs. Emergency physicians attend to patients with metabolic, inflammatory, endocrine, and toxic causes of myopathy more often than those with congenital causes because of the acute or subacute onset of symptoms associated with noncongenital forms.[3]

Periodic paralyses are a group of diseases that cause patients to present with acute weakness due to potassium shifts, leading to muscle dysfunction. A genetic defect of the sodium ion channel in muscle cell membranes is responsible for the paralysis, which may last from hours to days.

PreviousNextMortality/MorbidityMorbidity and mortality of myopathies is related to the etiology of the condition, severity of disease, and the presence of comorbid conditions. Severe weakness may lead to respiratory failure and death.Race

Thyrotoxic hypokalemic periodic paralysis is known to occur in Asian men, and one study suggests that Polynesians are also at risk for this condition.[4]

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Pericardial Effusion

Practice Essentials

Pericardial effusion is the presence of an abnormal amount of fluid and/or an abnormal character to fluid in the pericardial space. It can be caused by a variety of local and systemic disorders, or it may be idiopathic.

Essential update: Percutaneous balloon pericardiotomy for malignant pericardial effusion

According to a new study, percutaneous balloon pericardiotomy is safe and effective in the prevention of recurrence of severe malignant pericardial effusion.[1] In this retrospective study, 16 patients underwent percutaneous balloon pericardiotomy procedures, and investigators reported that the procedures were successful and that there were no acute or infectious complications during a mean follow-up of 44 days. Pleural effusion that did not require treatment developed in 1 patient; 3 patients required a new pericardial procedure; 2 had elective pericardial window surgeries; and 1 underwent a second percutaneous balloon pericardiotomy.[1]

Signs and symptoms

Signs and symptoms of pericardial effusion include the following:

Chest pain, pressure, discomfortLight-headedness, syncopePalpitationsCoughDyspneaHoarsenessAnxiety and confusionHiccoughs

See Clinical Presentation for more detail.

Diagnosis

Examination findings in patients with pericardial effusion include the following:

Classic Beck triad of pericardial tamponade: Hypotension, muffled heart sounds, jugular venous distentionPulsus paradoxusPericardial friction rubTachycardiaHepatojugular refluxTachypneaDecreased breath soundsEwart sign: Dullness to percussion beneath the angle of left scapulaHepatosplenomegalyWeakened peripheral pulses, edema, and cyanosis

Lab tests

The following laboratory studies may be performed in patients with suspected pericardial effusion:

Electrolyte levelsCBC count with differentialCardiac biomarker levels (eg, troponin, CK-MB, LDH)Tests for other markers of inflammation (eg, ESR, CRP)TSH levelBlood culturesRF levelsImmunoglobulin complex testsANA testsComplement levelsPericardial fluid analysis

Early in the course of acute pericarditis, the ECG typically displays diffuse ST elevation in association with PR depression; the ST elevation is usually present in all leads except for aVR, although in postmyocardial infarction pericarditis, the changes may be more localized.

Specific tests for infectious diseases or other conditions may also be warranted, based upon clinical suspicion, such as the following:

Viral culturesTuberculin skin testing or QuantiFERON-TB assayRickettsial antibodiesHIV serologyAdenosine deaminase levelsCEA levelsPCR

Imaging studies

Echocardiography is the imaging modality of choice for the diagnosis of pericardial effusion and includes the following techniques:

2-D echocardiographyM-mode echocardiography: Adjunct to 2-D echocardiographyDoppler echocardiographyTransesophageal echocardiographyIntracardiac echocardiography

Other radiologic studies used in the evaluation of pericardial effusion include the following:

Chest radiographyChest CT Scanning and MRI: May be superior to echocardiography in detecting loculated pericardial effusions

Procedures

Procedures that may be used in patients with pericardial effusion include the following:

Diagnostic and/or therapeutic pericardiocentesisDiagnostic pericardioscopyPlacement of a pulmonary artery catheter

See Workup for more detail.

Management

Most acute idiopathic or viral pericarditis occurrences are self-limited and respond to treatment with an NSAID. Prednisone may be administered for severe inflammatory pericardial effusions or when NSAID treatment has failed.

Autoimmune pericardial effusions may respond to treatment with anti-inflammatory medications. In general, selection of an agent depends on the severity of the patient's symptoms and the tolerability and adverse-effect profiles of the medications.

Pharmacotherapy for pericardial effusion includes use of the following agents, depending on the etiology:

NSAIDs (eg, indomethacin, ibuprofen, naproxen, diclofenac, ketoprofen, aspirin)Corticosteroids (eg, prednisone, methylprednisolone, prednisolone)Anti-inflammatory agents (eg, colchicine)Antibiotics (eg, vancomycin, ceftriaxone, ciprofloxacin, isoniazid, rifampin, pyrazinamide, ethambutol)Antineoplastic therapy (eg, systemic chemotherapy, radiation)Sclerosing agents (eg, tetracycline, doxycycline, cisplatin, 5-fluorouracil)

Hemodynamic support for pericardial effusion includes the following:

Hemodynamic monitoring with a balloon flotation pulmonary artery catheterIV fluid resuscitation

Surgical treatments for pericardial effusion include the following:

PericardiostomyPericardotomyThoracotomySternotomyPericardiocentesis

See Treatment and Medication for more detail.

Image libraryThis image is from a patient with malignant pericardial effusion. Note the "water-bottle" appearance of the cardiac silhouette in the anteroposterior (AP) chest film. NextBackground

Pericardial effusion is the presence of an abnormal amount of and/or an abnormal character to fluid in the pericardial space. It can be caused by a variety of local and systemic disorders, or it may be idiopathic. (See Etiology.)

Pericardial effusions can be acute or chronic, and the time course of development has a great impact on the patient's symptoms. Treatment varies, and is directed at removal of the pericardial fluid and alleviation of the underlying cause, which usually is determined by a combination of fluid analysis and correlation with comorbid illnesses (see the image below). (See Presentation, Workup, Treatment, and Medication.)

This image is from a patient with malignant pericardial effusion. Note the "water-bottle" appearance of the cardiac silhouette in the anteroposterior (AP) chest film. Embryology

In the human embryo, the pericardial cavity develops from the intraembryonic celom during the fourth week. The pericardial cavity initially communicates with the pleural and peritoneal cavities, but during normal development these are separated by the eighth week.

The visceral and parietal pericardium are derived from the mesoderm, albeit from different parts of the embryo. The visceral pericardium develops from splanchnic mesoderm, as cells originating from the sinus venous spread out over the myocardium. The parietal pericardium derives from lateral mesoderm that covers and accompanies the developing pleuropericardial membrane, which will eventually separate the pleural and pericardial cavities. In healthy subjects, the pericardium covers the heart and great vessels, with the exception of only partially covering the left atrium.

Congenital absence of the pericardium can occur and can be either partial or complete. This condition is often clinically silent, but it can potentially lead to excessive cardiac motion (in the case of complete absence), causing vague chest pain or dyspnea, or, in the case of partial absence with significant defects, strangulation of heart muscle and possible death.[2]

Physiology

The pericardial space normally contains 15-50 mL of fluid, which serves as lubrication for the visceral and parietal layers of the pericardium. This fluid is thought to originate from the visceral pericardium and is essentially an ultrafiltrate of plasma. Total protein levels are generally low; however, the concentration of albumin is increased in pericardial fluid owing to its low molecular weight.

The pericardium and pericardial fluid provide important contributions to cardiac function, including the following:

The parietal pericardium contributes to resting diastolic pressure, and is responsible for most of this pressure in the right atrium and ventricle Through their ability to evenly distribute force across the heart, the pericardial structures assist in ensuring uniform contraction of the myocardium

The normal pericardium can stretch to accommodate a small amount of fluid without a significant change in intrapericardial pressure, although once this pericardial reserve volume is surpassed, the pressure-volume curve becomes steep. With slow increases in volume, however, pericardial compliance can increase to lessen the increase in intrapericardial pressure.

PreviousNextPathophysiology

Clinical manifestations of pericardial effusion are highly dependent on the rate of accumulation of fluid in the pericardial sac. Rapid accumulation of pericardial fluid may cause elevated intrapericardial pressures with as little as 80 mL of fluid, while slowly progressing effusions can grow to 2 L without symptoms.

Understanding the properties of the pericardium can help to predict changes within the heart under physiologic stress.

By distributing forces across the heart, the pericardium plays a significant role in the physiologic concept of ventricular interdependence, whereby changes in pressure, volume, and function in one ventricle influence the function of the other.

The pericardium plays a pivotal role in cardiac changes during inspiration. Normally, as the right atrium and ventricle fill during inspiration, the pericardium limits the ability of the left-sided chambers to dilate. This contributes to the bowing of the atrial and ventricular septums to the left, which reduces left ventricular (LV) filling volumes and leads to a drop in cardiac output. As intrapericardial pressures rise, as occurs in the development of a pericardial effusion, this effect becomes pronounced, which can lead to a clinically significant fall in stroke volume and eventually progress to the development of pericardial tamponade.

The pericardium plays a beneficial role during hypervolemic states by limiting acute cardiac cavitary dilatation.

PreviousNextEtiology

The cause of abnormal fluid production depends on the underlying etiology, but it is usually secondary to injury or insult to the pericardium (ie, pericarditis). Transudative fluids result from obstruction of fluid drainage, which occurs through lymphatic channels. Exudative fluids occur secondary to inflammatory, infectious, malignant, or autoimmune processes within the pericardium.

In up to 60% of cases, pericardial effusion is related to a known or suspected underlying process. Therefore, the diagnostic approach should give strong consideration to coexisting medical conditions.

Idiopathic

In many cases, the underlying cause is not identified. However, this often relates to the lack of extensive diagnostic evaluation.

Infectious

Human immunodeficiency virus (HIV) infection can lead to pericardial effusion through several mechanisms, including the following:

Secondary bacterial infectionOpportunistic infectionMalignancy (Kaposi sarcoma, lymphoma)"Capillary leak" syndrome, which is associated with effusions in other body cavities

The most common cause of infectious pericarditis and myocarditis is viral. Common etiologic organisms include coxsackievirus A and B, and hepatitis viruses. Other forms of infectious pericarditis include the following:

Pyogenic - Pneumococci, streptococci, staphylococci, Neisseria, Legionella speciesTuberculousFungal - Histoplasmosis, coccidioidomycosis, CandidaSyphiliticProtozoalParasiticNeoplastic

Neoplastic disease can involve the pericardium through the following mechanisms:

Direct extension from mediastinal structures or the cardiac chamberRetrograde extension from the lymphatic systemHematologic seeding

Malignancies with the highest prevalence of pericardial effusion include lung (37% of malignant effusions) and breast (22%) malignancies, as well as leukemia/lymphoma (17%). However, patients with malignant melanoma or mesothelioma also have a high prevalence of associated pericardial effusions.

Postoperative/postprocedural

Pericardial effusions are common after cardiac surgery. In 122 consecutive patients studied serially before and after cardiac surgery, effusions were present in 103 patients; most appeared by postoperative day 2, reached their maximum size by postoperative day 10, and usually resolved without sequelae within the first postoperative month.

In a retrospective survey of more than 4,500 postoperative patients, only 48 were found to have moderate or large effusions by echocardiography; of those, 36 met diagnostic criteria for tamponade. The use of preoperative anticoagulants, valve surgery, and female sex were associated with a higher prevalence of tamponade.[3]

Symptoms and physical findings of significant postoperative pericardial effusions are frequently nonspecific, and echocardiographic detection and echo-guided pericardiocentesis, when necessary, are safe and effective; prolonged catheter drainage reduces the recurrence rate.[4]

Pericardial effusions in cardiac transplant patients are associated with an increased prevalence of acute rejection.[5]

Other

Less common causes of pericardial effusion include the following:

UremiaMyxedemaSevere pulmonary hypertensionRadiation therapyAcute myocardial infarction - Including the complication of free wall ruptureAortic dissection - Leading to hemorrhagic effusion from leakage into the pericardial sacTraumaHyperlipidemiaChylopericardiumFamilial Mediterranean feverWhipple diseaseHypersensitivity or autoimmune related -Systemic lupus erythematosus,[6] rheumatoid arthritis, ankylosing spondylitis, rheumatic fever, scleroderma, Wegener granulomatosis Drug associated - Eg, procainamide, hydralazine, isoniazid, minoxidil, phenytoin, anticoagulants, methysergidePreviousNextEpidemiologyOccurrence in the United States

Few large studies have characterized the epidemiology of pericardial effusion; however, the available data consistently show that pericardial effusion is more prevalent than is clinically evident. A higher incidence of it is associated with certain diseases.

Small pericardial effusions are often asymptomatic, and pericardial effusion has been found in 3.4% of subjects in general autopsy studies.

A wide variety of malignant neoplasms and hematologic malignancies can lead to pericardial effusion. Data on the prevalence varies, with some studies showing the presence of pericardial effusion as high as 21% in such patients. A large study by Bussani et al showed cardiac metastases (9.1%) and pericardial metastases (6.3%) in cases of death from all causes in individuals with an underlying carcinoma at autopsy.[7] As previously mentioned, malignancies with the highest prevalence of pericardial effusion include lung (37% of malignant effusions) and breast (22%) malignancies, as well as leukemia/lymphoma (17%).

Patients with HIV, with or without acquired immunodeficiency syndrome (AIDS), are also found to have an increased prevalence of pericardial effusion.[8] Studies have shown the prevalence of pericardial effusion in these patients to range from 5-43%, depending on the inclusion criteria, with 13% having moderate to severe effusion. The incidence of pericardial effusion in patients infected with HIV has been estimated at 11%; however, it appears that highly active antiretroviral therapy (HAART) may have reduced the incidence of HIV-associated effusions.[9]

Race- and age-related demographics

No consistent difference among races is reported in the literature. AIDS patients with pericardial effusion are more likely to be white.

Pericardial effusion is observed in all age groups. The mean occurrence is in the fourth or fifth decades, although it is earlier than this in patients with HIV.[8]

PreviousNextPrognosis

Most patients with acute pericarditis recover without sequelae. Predictors of a worse outcome include the following:

Fever greater than 38°CSymptoms developing over several weeks in association with immunosuppressed stateTraumatic pericarditisPericarditis in a patient receiving oral anticoagulantsA large pericardial effusion (>20 mm echo-free space or evidence of tamponade)Failure to respond to nonsteroidal anti-inflammatory drugs (NSAIDs)

In a series of 300 patients with acute pericarditis, 254 (85%) did not have any of the high-risk characteristics and had no serious complications. Of these low-risk patients, 221 (87%) were managed as outpatients and the other 13% were hospitalized when they did not respond to aspirin.

Patients with symptomatic pericardial effusions from HIV/AIDS or cancer have high short-term mortality rates.

Morbidity and mortality

The morbidity and mortality of pericardial effusion is dependent on etiology and comorbid conditions. Idiopathic effusions are well tolerated in most patients. As many as 50% of patients with large, chronic effusions (effusions lasting longer than 6 months) have been found to be asymptomatic during long-term follow-up.

Pericardial effusion is the primary or contributory cause of death in 86% of cancer patients with symptomatic effusions. The survival rate for patients with HIV and symptomatic pericardial effusion is 36% at 6 months and 19% at 1 year.

Pericardial tamponade

Pericardial tamponade, which is heralded by the equalization of diastolic filling pressures, can lead to severe hemodynamic compromise and death. It is treated with expansion of intravascular volume (small amounts of crystalloids or colloids may lead to improvement, especially in hypovolemic patients) and urgent pericardial drainage. Positive-pressure ventilation should be avoided, if possible, as this decreases venous return and cardiac output. Vasopressor agents are of little clinical benefit.

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Cardiac Tamponade

Background

Cardiac tamponade is a clinical syndrome caused by the accumulation of fluid in the pericardial space, resulting in reduced ventricular filling and subsequent hemodynamic compromise. The condition is a medical emergency, the complications of which include pulmonary edema, shock, and death. (See Pathophysiology, Etiology, and Prognosis.)

The overall mortality risk depends on the speed of diagnosis, the treatment provided, and the underlying cause of the tamponade. Untreated, the condition is rapidly and universally fatal (see the image below). (See Presentation, Workup, Treatment, and Medication.)

This anteroposterior-view chest radiograph shows a massive, bottle-shaped heart and conspicuous absence of pulmonary vascular congestion. Reproduced with permission from Chest, 1996: 109:825. NextPathophysiology

The pericardium, which is the membrane surrounding the heart, is composed of 2 layers. The thicker parietal pericardium is the outer fibrous layer; the thinner visceral pericardium is the inner serous layer. The pericardial space normally contains 20-50mL of fluid.

Reddy et al describe 3 phases of hemodynamic changes in tamponade.[1]

Phase I - The accumulation of pericardial fluid causes increased stiffness of the ventricle, requiring a higher filling pressure; during this phase, the left and right ventricular filling pressures are higher than the intrapericardial pressure Phase II - With further fluid accumulation, the pericardial pressure increases above the ventricular filling pressure, resulting in reduced cardiac output (see the Cardiac Output calculator) Phase III - A further decrease in cardiac output occurs, which is due to the equilibration of pericardial and left ventricular (LV) filling pressures

Pericardial effusions, which cause cardiac tamponade, can be serous, serosanguineous, hemorrhagic, or chylous.

The underlying process for the development of tamponade is a marked reduction in diastolic filling, which results when transmural distending pressures become insufficient to overcome increased intrapericardial pressures. Tachycardia is the initial cardiac response to these changes to maintain the cardiac output.

Systemic venous return is also altered during tamponade. Because the heart is compressed throughout the cardiac cycle due to the increased intrapericardial pressure, systemic venous return is impaired and right atrial and right ventricular collapse occurs. Because the pulmonary vascular bed is a vast and compliant circuit, blood preferentially accumulates in the venous circulation, at the expense of LV filling. This results in reduced cardiac output and venous return.

The amount of pericardial fluid needed to impair diastolic filling of the heart depends on the rate of fluid accumulation and the compliance of the pericardium. Rapid accumulation of as little as 150mL of fluid can result in a marked increase in pericardial pressure and can severely impede cardiac output,[2] whereas 1000 mL of fluid may accumulate over a longer period without any significant effect on diastolic filling of the heart. This is due to adaptive stretching of the pericardium over time. A more compliant pericardium can allow considerable fluid accumulation over a longer period without hemodynamic insult.

PreviousNextEtiology

For all patients, malignant diseases are the most common cause of pericardial tamponade. Among etiologies for tamponade, Merce et al reported the following incidence rates:

Malignant diseases - 30-60% of casesUremia - 10-15% of casesIdiopathic pericarditis - 5-15%Infectious diseases - 5-10%Anticoagulation - 5-10%Connective tissue diseases - 2-6%Dressler or postpericardiotomy syndrome - 1-2%

Tamponade can occur as a result of any type of pericarditis. Pericarditis can result from the following[3] :

Human immunodeficiency virus (HIV) infectionInfection - Viral, bacterial (tuberculosis), fungalDrugs - Hydralazine, procainamide, isoniazid, minoxidilPostcoronary intervention - Ie, coronary dissection and perforationAcupuncture[4] Postcardiac percutaneous procedures - Including mitral valvuloplasty, atrial septal defect (ASD) closure, left atrial appendage occlusion Trauma to the chestCardiovascular surgery - Postoperative pericarditis[5] Postmyocardial infarction - Free wall ventricular rupture, Dressler syndromeConnective tissue diseases - Systemic lupus erythematosus, rheumatoid arthritis, dermatomyositisRadiation therapy to the chestIatrogenic[6] - After sternal biopsy, transvenous pacemaker lead implantation, pericardiocentesis, or central line insertion UremiaAnticoagulation treatmentIdiopathic pericarditisComplication of surgery at the esophagogastric junction - Eg, antireflux surgeryPneumopericardium - Due to mechanical ventilation or gastropericardial fistulaHypothyroidismStill diseaseDuchenne muscular dystrophyType A aortic dissectionPreviousNextEpidemiologyOccurrence in the United States

The incidence of cardiac tamponade is 2 cases per 10,000 population in the United States. Approximately 2% of penetrating injuries are reported to result in cardiac tamponade.

Sex- and age-related demographics

In children, cardiac tamponade is more common in boys than in girls, with a male-to-female ratio of 7:3. In adults, cardiac tamponade appears to be slightly more common in men than in women. A male-to-female ratio of 1.25:1 was observed at the author's referral center, based on the International Classification of Diseases (ICD) code 423.9. However, a male-to-female ratio of 1.7:1 was observed at another level 1 trauma center.

Cardiac tamponade related to trauma or HIV is more common in young adults, whereas tamponade due to malignancy and/or renal failure occurs more frequently in elderly individuals.

PreviousNextPrognosis

Cardiac tamponade is a medical emergency. The prognosis depends on prompt recognition and management of the condition and the underlying cause of the tamponade. Untreated, cardiac tamponade is rapidly and universally fatal.

In addition to treatment for the tamponade, all patients should also receive treatment for the condition’s underlying cause in order to prevent recurrence.

In a study of patients with cardiac tamponade, Cornily et al reported a 1-year mortality rate of 76.5% in patients whose tamponade was caused by malignant disease, compared with 13.3% in patients with no malignant disease. The investigators also noted a median survival of 150 days in patients with malignant disease.[7]

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Restrictive Cardiomyopathy

Background

Restrictive cardiomyopathy (RCM) is a rare disease of the myocardium and is the least common of the 3 clinically recognized and described cardiomyopathies.[1] Its principal abnormality is diastolic dysfunction—specifically, restricted ventricular filling. RCM accounts for approximately 5% of all cases of primary heart muscle disease.

The World Health Organization (WHO) defines RCM as a myocardial disease characterized by restrictive filling and reduced diastolic volume of either or both ventricles with normal or near-normal systolic function and wall thickness. Increased interstitial fibrosis may be present. This disease may be idiopathic or associated with other diseases (eg, amyloidosis and endomyocardial disease with or without hypereosinophilia). The course of RCM varies, depending on the pathology and treatment, but is often unsatisfactory.

The importance of an accurate diagnosis of RCM is to distinguish this condition from constrictive pericarditis, a clinically and hemodynamically similar entity that also presents with restrictive physiology but is frequently curable by surgical intervention. This distinction is difficult to make but crucial because the treatment options and prognoses for the 2 conditions differ drastically.[2]

In the past, the correct diagnosis of RCM was frequently not made until surgical inspection demonstrated the pericardium of normal thickness and appearing normal. A subsequent myocardial biopsy would prove the diagnosis of RCM. With the improvement in diagnostic imaging, the necessity of progressing to surgical intervention to confirm the diagnosis of RCM (or constrictive pericarditis) should decrease.

NextPathophysiology

RCM can be idiopathic or secondary to a heart muscle disease that manifests as restrictive physiology.[1, 3] The disease creates increased stiffness of the myocardium, which causes pressure within the ventricles to rise precipitously with small increases in volume. Thus, accentuated filling occurs in early diastole, which terminates abruptly at the end of the rapid filling phase. When pressure tracings are taken at this point, they show a characteristic diastolic “dip-and-plateau” or “square-root” pattern, both similar to constrictive pericarditis.[4]

Patients typically have diastolic heart failure, meaning that systolic function is normal but the left ventricle has increased diastolic stiffness (reduced compliance) and cannot fill adequately at normal diastolic pressures, leading to reduced cardiac output as a result of reduced left ventricular filling volume. Systolic function usually remains normal, at least early in the disease; wall thickness is typically increased secondary to myocardial infiltration with amyloidosis, but the increase is usually not as pronounced as that observed in hypertrophic cardiomyopathy.

A variable reduction in systolic function may be present as the disease progresses. Reduced left ventricular filling volume leads to reduced stroke volume and low cardiac output symptoms (eg, fatigue, lethargy), whereas increased filling pressures cause pulmonary and systemic congestion. Thus, RCM causes symptoms and signs of left-side failure, right-side failure, or both because it affects both ventricles, but amyloidosis typically presents with dominant right-side fluid retention.

Some patients may have complete heart block as a consequence of fibrosis encasing the sinoatrial or the atrioventricular nodes. Interestingly, amyloid deposition in the bundle branches is rare.

On the basis of pathology, RCM can be classified as obliterative (ie, thrombus-filled ventricles) or nonobliterative/idiopathic.

Obliterative RCM is very rare. It may result from the end stage of the eosinophilic syndromes, in which an intracavitary thrombus fills the left ventricular apex and hampers the filling of the ventricles. The fibrosis of the endocardium may extend to involve the atrioventricular valves and cause regurgitation. Two forms of endomyocardial fibrosis (EMF) exist—an active inflammatory eosinophilia and chronic EMF.

In idiopathic (primary) RCM, progressive fibrosis of the myocardium occurs, but no thrombus forms. This entity also is said to lack specific histopathologic changes.

PreviousNextEtiology

RCM may be caused by various local and systemic disorders; many of them are rare and unlikely to be observed in the United States. These causes may be grouped into 4 broad categories as follows:

IdiopathicInfiltrativeTreatment-inducedMalignancy

According to WHO guidelines, the term “cardiomyopathy” refers to diseases of the myocardium that are idiopathic (ie, primary cardiomyopathies). However, secondary infiltrative myocardial diseases, which are actually cardiac manifestations of systemic diseases, often are grouped together with cardiomyopathies.[5]

Idiopathic RCM may be caused by EMF or by Loeffler eosinophilic endomyocardial disease. Secondary restrictive cardiomyopathy may be caused by the following:

HemochromatosisAmyloidosis[6] (the most common cause of RCM in the United States) SarcoidosisProgressive systemic sclerosis (scleroderma)Carcinoid heart diseaseGlycogen storage disease of the heartRadiationMetastatic malignancyAnthracycline toxicityIdiopathic/primary RCM

A subset of patients have heart muscle disease of unknown cause that is manifested by heart failure and restrictive hemodynamics but is not characterized by significant ventricular hypertrophy, endocardial thickening or fibrosis, associated eosinophilia, or other diagnostically distinct histopathologic changes.

Males and females have been affected equally, but the prognosis appears to be worse in children than in adults. Children require relatively high filling pressures for maintenance of systolic output, and the therapeutic margin between volume depletion (leading to low output) and volume overload (leading to congestive heart failure) is narrow. A familial pattern has been noted in some cases.

In addition to the presenting symptoms of right- and left-side heart failure, as many as one third of patients with idiopathic RCM may present with thromboembolic complications. Pathologically, these patients have strikingly dilated atria, which may account for the increased cardiothoracic ratio on chest radiography. Echocardiography shows bilateral atrial enlargement with normal ventricular size but significant diffuse left ventricular hypertrophy, especially with amyloidosis. Histologic features include interstitial fibrosis, which is minimal in some and extensive in others.

Amyloidosis

Amyloidosis is characterized by intercellular accumulation of amyloid material in amounts sufficient to impair the function of the involved organs. On the basis of the amyloid protein composition, amyloidosis is classified into 4 different varieties as follows:

Primary or myeloma-related amyloidosisSecondary amyloidosis (ie, secondary to chronic diseases)Senile amyloidosisFamilial amyloidosis

The cardiac involvement in primary amyloidosis most commonly is associated with restrictive physiology. Amyloid infiltration of the heart is common in the elderly population (systemic senile amyloidosis) and may exhibit impaired diastolic filling properties but has other features that are more typical of a dilated cardiomyopathy.

The myeloma protein fibrils composed of immunoglobulin light chains are deposited diffusely throughout the myocardium and create a firm and rubbery consistency. Typically, the heart does not collapse when removed from the chest during autopsy.

On histologic examination, interstitial deposition of insoluble amyloid fibrils in all 4 cardiac chambers is observed. This can result in increased wall thickness without cavity dilatation.

Involvement of the valves may create regurgitant lesions, but hemodynamically and clinically significant degree of regurgitation is unusual.

The granular sparkling (ie, scintillating) appearance on 2-dimensional echocardiography may be present and is typical, but not diagnostic, of cardiac amyloidosis. Echocardiography more typically shows biventricular thickening out of proportion to current or prior hypertension, biatrial enlargement, a restrictive filling pattern by Doppler echocardiography, and normal systolic function and ejection fraction until late in the disease.

In the early stages of the disease, typical restrictive hemodynamics may not be evident; however, in more advanced cases, typical restrictive hemodynamics are more likely. A corollary of these observations is that restrictive diastolic dynamics strongly predict cardiac death in patients with amyloidosis. Cardiac biopsy is needed to confirm the diagnosis if doubt remains after noninvasive tests.

Eosinophilic cardiomyopathy and EMF

Severe prolonged eosinophilia from any cause (eg, allergic, autoimmune, parasitic, leukemic, or idiopathic) can lead to eosinophilic infiltration of the myocardium. The intracytoplasmic granular content of activated eosinophils is believed to be responsible for the toxic damage to the heart. This eosinophilic cardiomyopathy, also known as Loeffler endocarditis, is associated with dense EMF, intraventricular thrombus formation, and obliteration of the ventricular cavity in its late stages; accordingly, it is included in the category of obliterative RCM.

EMF, which is observed exclusively in equatorial Africa and less frequently in Asia and South America, was believed to be the end stage of eosinophilic endomyocarditis. However, it now is considered a separate entity because it does not exhibit eosinophilia. EMF demonstrates pathology that is similar to that described above (Loeffler endocarditis) and therefore is grouped under obliterative RCM.

The prognosis is poor for patients with diffuse involvement of the heart in EMF, but localized lesions involving the valves are amenable to surgical repair or removal and replacement.

Postirradiation fibrosis

Radiation-induced myocardial and endocardial fibrosis also can cause RCM. However, this complication of radiotherapy, like pericardial constriction, is evident several years after treatment. Differentiating between constriction and restriction may be particularly difficult in these patients because the 2 conditions may coexist.

PreviousNextEpidemiology

Idiopathic restrictive cardiomyopathy is observed mainly in the United States. Loeffler endocarditis is common in the temperate zone, and chronic EMF is observed in the tropics. EMF occurs most commonly in children and young adults in tropical and subtropical Africa, primarily in Uganda and Nigeria.[7] EMF may account for up to one fourth of deaths due to cardiac disease in those areas

PreviousNextPrognosis

The course of RCM varies depending on the pathology, and treatment is often unsatisfactory. Prognosis generally is poor in the adult population, with progressive deterioration. The natural history of RCM is especially poor in children with heart failure. Adults experience a prolonged course of heart failure and may have complications of cardiac cirrhosis and thromboembolism. Patients who are refractory to supportive therapy usually die of low-output cardiac failure unless cardiac transplantation is an option.

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Emergent Management of Acute Aortic Dissection

Overview

Aortic dissection is the most common catastrophe of the aorta, 2-3 times more common than rupture of the abdominal aorta. When left untreated, about 33% of patients die within the first 24 hours, and 50% die within 48 hours. The 2-week mortality rate approaches 75% in patients with undiagnosed ascending aortic dissection.

The establishment of the International Registry of Acute Aortic Dissection in 1996, which gathers information from 24 centers in 11 countries, has helped in the development of an understanding of the complexity of aortic dissection.

Dissections of the thoracic aorta have been classified anatomically by 2 different methods. The more commonly used system is the Stanford classification, which is based on involvement of the ascending aorta and simplifies the DeBakey classification.

Go to Aortic Dissection for complete information on this topic.

Stanford classification

The Stanford classification divides dissections into 2 types, type A and type B. Type A involves the ascending aorta (DeBakey types I and II); type B does not (DeBakey type III).

This system helps to delineate treatment. Usually, type A dissections require surgery, while type B dissections may be managed medically under most conditions.

DeBakey classification

The DeBakey classification divides dissections into 3 types, as follows:

Type I involves the ascending aorta, aortic arch, and descending aortaType II is confined to the ascending aortaType III is confined to the descending aorta distal to the left subclavian artery

Type III dissections are further divided into IIIa and IIIb. Type IIIa refers to dissections that originate distal to the left subclavian artery but extend proximally and distally, mostly above the diaphragm.

Type IIIb refers to dissections that originate distal to the left subclavian artery, extend only distally, and may extend below the diaphragm.

Thoracic aortic dissections should be distinguished from aneurysms (ie, localized abnormal dilation of the aorta) and transections, which are caused most commonly by high-energy trauma.

NextPrehospital Care

Assure adequate breathing, maintain oxygenation, treat shock, and obtain useful historical information.

Establishing the diagnosis in the field is usually difficult or impossible, but certain salient features of aortic dissection may be observed. It is life threatening if not quickly recognized and treated.

Radio communication with the receiving hospital permits the medical control physician to direct care and select a capable destination hospital, while permitting the emergency department (ED) to mobilize appropriate resources.

In the rare event that the diagnosis can be made based on prehospital information, the physician directing prehospital care should request transport to a facility capable of operative treatment of an aortic dissection.

PreviousNextEmergency Department Care

The mortality rate of patients with aortic dissection is 1-2% per hour for the first 24-48 hours. Initial therapy should begin when the diagnosis is suspected. This includes 2 large-bore intravenous lines (IVs), oxygen, respiratory monitoring, and monitoring of cardiac rhythm, blood pressure, and urine output.

Clinically, the patient must be assessed frequently for hemodynamic compromise, mental status changes, neurologic or peripheral vascular changes, and development or progression of carotid, brachial, and femoral bruits.

Aggressive management of heart rate and blood pressure should be initiated.

Beta blockers should be given initially to reduce the rate of change of blood pressure (dP/dt) and the shear forces on the aortic wall.

The target heart rate should be 60-80 beats per minute.

The target systolic blood pressure should be 100-120 mm Hg.

End organ perfusion should be evaluated. Balancing the risks of dP/dt on the aortic wall versus the benefits of acceptable end organ perfusion may be a difficult clinical decision.

Retrograde cerebral perfusion may increase the protection of the central nervous system during the arrest period.

The mortality rate from aortic arch dissections is about 10-15%, with significant neurologic complications occurring in another 10% of patients. The mortality rate is influenced by the patient's clinical condition.

The American College of Radiology has established ACR Appropriateness Criteria for the diagnosis and treatment of suspected aortic dissection.[1]

Type A dissections

Urgent surgical intervention is required in type A dissections.

The area of the aorta with the intimal tear usually is resected and replaced with a Dacron graft.

The operative mortality rate is usually less than 10%, and serious complications are rare with ascending aortic dissections.

The development of more impermeable grafts, such as woven Dacron, collagen-impregnated Hemashield (Meadox Medicals, Oakland, NJ), aortic grafts, and gel-coated Carbo-Seal Ascending Aortic Prothesis (Sulzer CarboMedics, Austin, Tex), has greatly enhanced the surgical repair of thoracic aortic dissections.

With the introduction of profound hypothermic circulatory arrest and retrograde cerebral perfusion, the morbidity and mortality rates associated with this highly invasive surgery have decreased.

Dissections involving the arch are more complicated that those involving only the ascending aorta, because the innominate, carotid, and subclavian vessels branch from the arch. Deep hypothermic arrest usually is required. If the arrest time is less than 45 minutes, the incidence of central nervous system complications is less than 10%.

Aortic stent grafting is a challenging technique. It may prove feasible and has offered good results in a small series of patients. It may be a reasonable alternative in high-risk patients in the near future.

Type B dissections

The definitive treatment for type B dissections is less clear.

Uncomplicated distal dissections may be treated medically to control blood pressure. Distal dissections treated medically have a mortality rate that is the same as or lower than the mortality rate in patients who are treated surgically.

Surgery is reserved for distal dissections that are leaking, ruptured, or compromising blood flow to a vital organ.

Acute distal dissections in patients with Marfan syndrome usually are treated surgically.

Inability to control hypertension with medication is also an indication for surgery in patients with a distal thoracic aortic dissection.

Patients with a distal dissection are usually hypertensive, emphysematous, or older.

Long-term medical therapy involves a beta-adrenergic blocker combined with other antihypertensive medications. Avoid antihypertensives (eg, hydralazine, minoxidil) that produce a hyperdynamic response that would increase dP/dt (ie, alter the duration of P or T waves).

Survivors of surgical therapy also should receive beta-adrenergic blockers.

A series of patients with type B dissections demonstrated that aggressive use of distal perfusion, CSF drainage, and hypothermia with circulatory arrest improves early mortality and long-term survival rates.

Endovascular stenting remains an option for treatment of some type B dissections. Some studies recommend that patients with complicated acute type B dissections undergo endovascular stenting with the goal of covering the primary intimal tear.[2]

Definitive treatment

Definitive treatment involves segmental resection of the dissection, with interposition of a synthetic graft.

When thoracic dissections are associated with aortic valvular disease, replace the defective valve.

With combined reconstruction–valve replacement, the operative mortality rate is approximately 5%, with a late mortality rate of less than 10%.

Operative repair of the transverse aortic arch is technically difficult, with an operative mortality rate of 10% despite induction of hypothermic cardiocirculatory arrest.

Repair of the descending aorta is associated with a higher incidence of paraplegia than repair of other types of dissections because of interruption of segmental blood supply to the spinal cord.

The operative mortality rate is approximately 5%.

In a study by Mimoun et al of patients with Marfan syndrome who had acute aortic dissection, the patients were found to have a better event-free survival when there were no dissected portions of the aorta remaining after surgery.[3]

PreviousNextConsultations

Once a thoracic dissection is suspected, consult a thoracic surgeon. Because many patients with this disorder have concomitant medical illness, consult the patient's primary care provider to expedite preoperative preparation. Early consultation is encouraged when ordering further imaging studies if the patient requires rapid operative intervention.

Consult a radiologist prior to obtaining aortography.

PreviousNextInpatient Care

Patients with symptomatic dissection should undergo immediate repair, especially if it is leaking or expanding.

Symptomatic patients require admission to a center experienced in cardiopulmonary bypass and operative care.

Completely asymptomatic patients may have their repair performed electively but may require admission to expedite their evaluation or for preoperative stabilization of their condition.

Patients with chest pain should undergo serial echocardiograms (ECGs) and creatine kinase (CK) determinations if acute myocardial infarction (AMI) is indicated.

PreviousNextOutpatient Care

Follow-up examinations with radiologic studies are recommended at 3-month intervals for the first year and every 6 months for the next 2 years.

After this, follow up annually.

PreviousNextTransfer

Symptomatic patients require care at a facility equipped to perform cardiopulmonary bypass with aortic and/or valvular repair.

Contact the receiving physician as soon as possible to transfer patients before their condition deteriorates.

Early airway management is indicated in the presence of hemoptysis or stridor.

If coronary insufficiency is suspected, nitrates may be used, but therapy with thrombolytic agents and aspirin should be avoided.

Patients should be monitored and accompanied by personnel capable of resuscitation.

If a prolonged ground transport time is anticipated, consider air transport.

Previous, Emergent Management of Acute Aortic Dissection

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Subclavian Vein Thrombosis

Background

Sir James Paget first described thrombosis of the subclavian veins in 1875.[1] He coined the name gouty phlebitis to describe the spontaneous thrombosis of the veins draining the upper extremity. He observed that the syndrome was accompanied by pain and swelling of the affected extremity. However, he incorrectly attributed the syndrome to vasospasm. In 1884, von Schrötter postulated that this syndrome resulted from occlusive thrombosis of the subclavian and axillary veins.[2] In recognition of the work of these pioneers, in 1949, Hughes coined the term Paget-von Schrötter syndrome.[3] A related condition is thrombosis of the subclavian vein that is induced by the presence of indwelling catheters. The incidence of this condition has increased remarkably over the past two decades because of the extensive use of catheters in patients with cancer and other chronic medical conditions.

See the images below.

This figure shows the area where the subclavian vein is obstructed in the neck area. The vein is usually compressed by the first rib, clavicle, and serratus anterior muscle. A venogram in a patient with subclavian vein obstruction. Long-standing obstruction causes development of collaterals. Recanalization after thrombolytic therapy and stent placement. Patient underwent first rib resection and scalenectomy later. NextHistory of the Procedure

Patients may describe a history of trauma or, more frequently, strenuous use of the arm (>50% of cases). Common precipitating activities involve repeated hyperabduction and external rotation of the arm or backward and downward rotation of the shoulder. Causative activities may include participating in cricket, tennis, wrestling, lifting weights, water polo, gymnastics, baseball, or chopping wood. Because the symptoms of subclavian stenosis are fairly dramatic, most patients present promptly to the emergency department, usually within 24 hours. They may report dull ache in the shoulder or axilla, and the pain often is worsened by activity. Conversely, rest and elevation often relieve the pain. Patients with catheter-associated axillary subclavian deep vein thrombosis (ASDVT) report similar symptoms of the ipsilateral arm or shoulder with the indwelling catheter.

PreviousNextEpidemiologyFrequency

Prior to 1967, thrombosis of the axillary or subclavian vein accounted for 1-2% of all cases of deep vein thrombosis. Since then, the incidence has risen due to the more frequent use of central venous access for multiple clinical conditions. Among patients with effort-induced thrombosis with subclavian vein stenosis, the thrombosis occurs in the dominant arm in 80% of cases.

PreviousNextEtiology

The primary etiology is referred to as effort-induced thrombosis or Paget-von Schrötter syndrome. It usually results from the excessive use of the involved arm by predisposed individuals.

The secondary etiology is subclavian vein catheterization, especially in patients with cancer. (For detailed descriptions of catheterization techniques, see Central Venous Access, Subclavian Vein, Subclavian Approach and Central Venous Access, Subclavian Vein, Supraclavicular Approach.) Other causes include transvenous pacemakers, factor V Leiden mutation, protein C deficiency, protein S deficiency, antithrombin III deficiency, and prothrombin 20210A mutation. Long-term parenteral nutrition and use of hemodialysis catheters account for some cases of subclavian vein thrombosis.[4] Trauma is only rarely associated with this syndrome.

In a few cases, the diagnosis remains unknown. However, routine follow-up with these patients has revealed the development of lung cancer within 1 year of follow-up. The most common lung malignancy associated with subclavian thrombosis has been the Pancoast tumor.

PreviousNextPathophysiology

During long term venous catheterization of the subclavian and internal jugular vein in cancer patients, the risk of complications appear to be similar. However, for short term catheterization, subclavian vein catheterization is recommended because of the decreased risks of thrombotic complications and catheter colonization by skin flora. For patients requiring hemodialysis, both the femoral and internal jugular veins appear to have similar thrombotic complications. However, the risk of mechanical complications via the internal jugular vein appear to be higher. The subclavian vein should be avoided for both long and short term hemodialysis as the risk of thrombosis is very high.[5]

Differentiating catheter-associated subclavian vein thrombosis and Paget-von Schrötter syndrome is important because they appear to have different natural histories.

Paget-von Schrötter syndrome

It sometimes is referred to as spontaneous axilla-subclavian vein thrombosis to express the usually dramatic unexpected presentation of the disorder in otherwise healthy, generally young individuals. Over the past 2 decades, recognition has grown that the disorder can occur equally in both sexes and can affect all age groups. In the 1960s, the term effort-induced thrombosis was used to describe this disease to acknowledge that it often follows unusually strenuous use of the arm or shoulder on the affected side.

The pathophysiology of effort-induced thrombosis is multifactorial. It involves compressive changes in the vessel wall, stasis of blood, and hypercoagulability. External compression of the axillary-subclavian vein has been suggested to contribute to the stasis of blood that engenders thrombosis.

The factors that cause external compression include (1) anomalous subclavius or anterior scalene muscle, long transverse process of cervical spine, cervical rib, abnormal insertion of the first rib, congenital fibromuscular bands, or narrowing of the costoclavicular space from depression of the shoulder; (2) stress from exercise temporarily causing hypercoagulability; and (3) repetitive shoulder-arm motion causing microscopic intimal tears in the vessel wall. These factors, taken together, satisfy the classic Virchow triad for thrombosis. Furthermore, coexistent hematologic abnormalities that can contribute to thrombosis include protein C deficiency, antithrombin III deficiency, factor V Leiden mutation, and prothrombin 20210A mutation.

Catheter-induced subclavian vein thrombosis

Introducing catheters and transvenous pacemakers in to the subclavian vein alters the venous flow and increases turbulence. This results in platelet aggregation, release of procoagulants, and, ultimately, fibrin deposition. This causes a further reduction in the lumen of the vessel due to thrombus formation, which eventually culminates in total vessel occlusion. Intravenous medications and even parenteral nutrition have been known to cause thrombophlebitis. In patients with cancer, an additional contributing factor is that the tumor may generate procoagulant factors, predisposing to thrombosis at sites remote from the tumor.

PreviousNextPresentation

Not all patients with subclavian vein thrombosis are symptomatic. Those with symptoms may present with mild-to-moderate nonpitting edema and mild cyanosis of the hands and fingers on the affected side. Dilatation of subcutaneous collateral veins may be present over the upper arm and chest. This later sign may be the only clue to ASDVT in otherwise asymptomatic patients with catheter-related venous thrombosis. In a few cases, in which the diagnosis was missed or delayed or the patient presented late, the thrombus may have extended to the superior vena cava. These patients show most features of the superior vena cava syndrome, including face and neck swelling, periorbital edema, blurred vision, and some degree of facial cyanosis.[6]

PreviousNextIndications

In patients with effort-induced vein thrombosis of less than 2 weeks duration, thrombolytic therapy is recommended. Chronic ASDVT does not respond to thrombolytics and is better treated either conservatively with warfarin, or by surgical bypass, if symptoms are severe.

PreviousNextRelevant Anatomy

The subclavian vein courses over the first rib and posterior to the clavicle. The artery lies superior and posterior to the vein.

PreviousNextContraindications

Surgery is rarely indicated in ASDVT associated with central lines. Thrombolytic drug therapy is rarely recommended for patients who present with chronic subclavian vein thrombosis.

PreviousProceed to Workup , Subclavian Vein Thrombosis

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Subclavian Artery Thrombosis

Background

Subclavian artery thrombosis is a condition in which the blood flow through the vessel is obstructed. The condition usually occurs secondary to some form of antecedent injury to the vessel, hypercoagulable state, or atherosclerotic changes. The condition is common in young athletic individuals who exert a significant amount of upper body activity.[1] Sudden occlusion from emboli followed by thrombosis of the artery is common in the population with signs of significant atherosclerotic disease.

The patient presenting with acute subclavian artery occlusion usually has a history of repetitive use and/or stress injury to the upper extremity on the affected side. A history of upper extremity claudication is common.

In situations in which the occlusion is secondary to atherosclerosis, acute thromboses of the artery are generally asymptomatic. In fact, in 9% of autopsy series, the left subclavian artery was either stenotic or occluded. If symptoms are present, upper extremity claudication on the affected side is most common. The patient may also present with dizziness, vertigo, imbalance, visual disturbances, or hemisensory dysfunction indicative of a subclavian steal syndrome. However, note that subclavian steal is observed on 2% of cerebral angiograms and causes no symptoms.

NextProblem

The occlusion arises secondary to damage to the intima of the artery. This damage can occur as a result of external muscular compression and repetitive stress to the artery or because of atherosclerotic changes to the vessel. Embolic phenomena and hypercoagulable states are also contributing factors.

Symptoms occur secondary to lack of blood flow to the affected extremity. To maintain blood supply to the extremity, blood is naturally rerouted from the vertebral, carotid, and internal mammary arteries, producing the various steal syndromes.

PreviousNextEpidemiologyFrequency

Symptomatic lesions occur in less than 1% of the population. In autopsy series, 9% of the population demonstrate stenosis or occlusion of one subclavian artery, usually on the left. Two percent of cerebral angiograms demonstrate asymptomatic subclavian steal.

PreviousNextEtiology

The occlusion arises secondary to damage to the intima of the artery. This damage can occur as a result of external muscular compression and repetitive stress to the artery, atherosclerotic changes to the vessel, or inflammatory processes.

Embolic or thrombotic occlusion of the artery occurs, particularly in the presence of atherosclerotic stenoses. Hypercoagulable states contribute to this scenario.

PreviousNextPathophysiology

The affected artery demonstrates detectable intimal damage, which is usually secondary to compressive forces exerted by the muscles of the shoulder girdle that compress the artery. Bony abnormalities in this area can also contribute to the process.[2] As these muscles enlarge secondary to physical activity, they exert pressure on the artery. This pressure, coupled with exertional activity of the upper extremity, can stretch and compress the intima, thus disrupting its natural integrity. This disruption precipitates platelet deposition in the area, with resulting thrombosis.

Atherosclerotic changes in the vessel occur secondary to the flow characteristics in the area. These depositions are accelerated by all of the dietary and sociological influences that affect the progression of atherosclerotic disease, including smoking, hypercholesterolemia, and hypertension. Occlusion secondary to atherosclerosis is more insidious and often causes no symptoms. At times, the symptom complex of claudication precedes the actual loss of blood flow.

Patients with hypercoagulable states, either intrinsic or secondary to dehydration complicated by concomitant cardiac arrhythmias and systemic inflammatory processes, comprise a small subset of individuals who may exhibit this pathology.

PreviousNextPresentation

A patient with an acute occlusion presents with a cold, painful, pulseless upper extremity. Axillary, brachial, and radial pulses are generally absent. When the occlusion is secondary to atherosclerotic changes, various prodromes and manifestations may be observed.

The patient may present with no symptoms or upper extremity claudication secondary to exertion. If the condition has precipitated a steal syndrome, no symptoms are typically present. The examining physician should be aware of the rare presentation of various neurological symptoms and findings that may be associated with the steal syndromes, including syncope, vertigo, ataxia, sensory loss, visual changes, and stroke, depending on the vessels involved in the steal. The affected upper extremity may or may not demonstrate diminished pulses. Blood pressure differences between the affected and unaffected sides may be noted.

PreviousNextIndications

Therapeutic intervention is indicated in any symptomatic patient once the etiology of the symptoms has been defined. For instances of upper extremity claudication or acute thrombosis in which the problem has been attributed to the subclavian artery, intervention should be planned and executed. For patients in whom cerebrovascular symptoms predominate, a careful neurological evaluation must be undertaken in order to isolate the problem. Once the anatomical aberration has been defined, intervention is indicated if the subclavian artery is involved.

PreviousNextRelevant Anatomy

In patients with subclavian artery occlusion secondary to variations in the thoracic outlet, 2 areas can undergo vascular compression during hyperabduction of the extremity. One site is where the axillary artery passes posterior to the pectoralis minor muscle and beneath the coracoid process. The other point is where the artery courses between the clavicle and the first rib. Fibrous tissue proliferation in this area can impose extrinsic compression on the vessel. The image below illustrates the relevant anatomy.

The anatomy of the subclavian artery in the thoracic outlet.

Aberrant origins of the subclavian artery off the aortic arch can be a cause of subclavian artery occlusion.[3]

In atherosclerotic disease, the carotid-subclavian junction or carotid-vertebral junctions are areas that appear to be predisposed to atheromata formation and calcification. Subsequently, this region is most likely to be involved in the occlusive process.[4]

Areas of the subclavian artery that are exposed to repeated forms of injury resulting in intimal damage are predisposed to occlusion.

PreviousNextContraindications

Contraindications to surgical intervention include inadequate distal runoff, inadequate vessel size, and marked collateralization of the occluded area. Concomitant medical problems that would endanger the patient during a surgical intervention are also contraindications to surgery. With the advent of stenting, patients with greater medical challenges can be treated successfully; however, the presence of appropriate arterial runoff and adequate artery size are imperative in order to ensure success of the procedure.

PreviousProceed to Workup , Subclavian Artery Thrombosis

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