Browse the corpus
Walk the Even Hospital Database by book and chapter — the raw source passages that ground Ask, DDx, and the rest.
21 passages
380 SECTION 7: Cardiovascular Disease Cardiomyopathies and Pericardial Disease Manpreet Singh James T. Niemann INTRODUCTION The term cardiomyopathy describes a heterogeneous group of diseases that directly alter cardiac structure, impair myocardial function, or alter myocardial electrical properties. Discoveries in molecular genetics and the description of (ion) channelopathies as diseases have prompted periodic revisions of definitions and classifications of cardiomyopathies. The MOGE(S) classification is the most recently proposed and describes the morphofunctional phenotype (M), organ(s) involvement (O), genetic inheritance pattern (G), etiology (E; which includes genetic defect or underlying disease), and functional status (S). 1,2 In simple terms, primary cardiomyopathies are diseases that solely or predominantly involve the myocardium and are usually familial in origin; the most common disorders are listed in Table 55-1. Secondary cardiomyopathies include heart muscle diseases associated with specific systemic disor ders. Secondary cardiomyopathies often present with morphofunctional phenotypes and hemodynamic findings similar to those of the dilated or restrictive forms of cardiomyopathy. The most common causes of sec ondary cardiomyopathies are listed in Table 55-2. As a group, cardiomyopathies are the third most common form of cardiac disease encountered in the United States, following coronary (ischemic) heart disease and hypertensive heart disease. Hypertrophic cardiomyopathy is the sec ond most common cause of sudden cardiac death in the adolescent population and the leading cause of sudden death in competitive athletes. An in-depth discussion of each of the primary familial and secondary cardiomyopathies is beyond the scope of this chapter, and emergency providers are unlikely to make a specific diagnosis in the ED. This chapter discusses selected cardiomyopathies ( Table 55-3). Arrhythmogenic ventricular cardiomyopathy is discussed in Chapter 130, “Syncope, Dysrhythmias, and ECG Interpretation in Children. ” The cardiomyopathies usually present with signs of systolic and diastolic ventricular dysfunc tion. The ED evaluation will generally guide the need for urgent treat ment, admission, or referral for further diagnostic evaluation.
is discussed in Chapter 130, “Syncope, Dysrhythmias, and ECG Interpretation in Children. ” The cardiomyopathies usually present with signs of systolic and diastolic ventricular dysfunc tion. The ED evaluation will generally guide the need for urgent treat ment, admission, or referral for further diagnostic evaluation. CHAPTER TABLE 55-1 The Primary Cardiomyopathies Genetic • Hypertrophic cardiomyopathy • Arrhythmogenic right ventricular cardiomyopathy/dysplasia • Left ventricular noncompaction • Conduction system disease • Long QT syndrome • Brugada syndrome • Short QT syndrome • Idiopathic ventricular fibrillation Mixed (genetic and nongenetic) • Dilated cardiomyopathy • Primary restrictive nonhypertrophied cardiomyopathy Acquired • Myocarditis (inflammatory cardiomyopathy) • Stress (takotsubo) cardiomyopathy • Peripartum cardiomyopathy TABLE 55-2 Common Causes of Secondary Cardiomyopathies Toxins • Ethanol • Chemotherapeutic agents (doxorubicin) • Antiretroviral agents (zidovudine, didanosine) • Phenothiazines • Cocaine • Methamphetamine Infiltrative diseases • Amyloidosis Storage diseases • Hemochromatosis Autoimmune disorders • Scleroderma • Systemic lupus erythematosus • Rheumatoid arthritis • Dermatomyositis Metabolic • Nutritional deficiency (thiamine, selenium) • Endocrine (diabetes mellitus, hypothyroidism, hyperthyroidism) • Electrolytic disturbance (hypophosphatemia, hypocalcemia) Neuromuscular disorders • Muscular dystrophy • Friedreich’s ataxia TABLE 55-3 Features of Selected Cardiomyopathies Type Cardiomyopathy Type Clinical Features ECG Systolic and diastolic dysfunction Dilated cardiomyopathy Congestive heart failure Chest pain Regurgitant murmurs LVH Poor R-wave progression Myocarditis Fever Tachycardia Myalgias Chest pain Nonspecific ST- T–wave changes Diastolic dysfunction Hypertrophic cardiomyopathy Dyspnea on exertion Chest pain Palpitations Syncope Pulsus bisferiens Systolic ejection murmur, increases with Valsalva and decreases with squatting LVH Large septal Q waves Restrictive cardiomyopathies Presentation as heart failure with preserved EF; may be confused with constrictive pericarditis In some, low voltage of QRS; conduction disturbances; atrial fibrillation Abbreviations: EF = ejection fraction; LVH = left ventricular hypertrophy. added step is low-dose oral vitamin K reversal, 1.0 to 2.5 milligrams. Patients with severe bleeding complications are best treated with fresh frozen plasma or prothrombin complex concentrate. 3 Avoid parenteral, high-dose vitamin K due to risk of overcorrection .9 REFERENCES The complete reference list is available online at www.TintinalliEM.com. Tintinalli_Sec07_p0329-0424.indd 380 8/2/19 6:42 PM
ith severe bleeding complications are best treated with fresh frozen plasma or prothrombin complex concentrate. 3 Avoid parenteral, high-dose vitamin K due to risk of overcorrection .9 REFERENCES The complete reference list is available online at www.TintinalliEM.com. Tintinalli_Sec07_p0329-0424.indd 380 8/2/19 6:42 PM CHAPTER 55: Cardiomyopathies and Pericardial Disease 381 CARDIOMYOPATHIES WITH SYSTOLIC AND DIASTOLIC DYSFUNCTION DILATED CARDIOMYOPATHY EPIDEMIOLOGY AND PATHOPHYSIOLOGY Dilated cardiomyopathy is not a single disease but should be viewed as a nonspecific phenotype. It may be familial or occur with specific cardiac or systemic disorders ( Tables 55-1 and 55-2). Peripartum cardiomyopathy most commonly manifests as dilated cardiomyopathy and is discussed in Chapter 99, “Comorbid Disorders in Pregnancy. ” The dilated cardiomyopathies are a major cause of heart failure and are a major indication for cardiac transplantation in the United States. Most patients with a familial form of dilated cardiomyopathy are diagnosed between the ages of 20 and 50 years, and the majority have advanced symptoms at the time of initial presentation. Dilated cardiomyopathy is characterized by systolic and diastolic dysfunction and diminished left ventricular (LV) and, often, right ven tricular contractile force, resulting in a low cardiac output and increased end-systolic and end-diastolic ventricular volumes. A decrease in ven tricular compliance leads to an increase in intracavitary pressures. LV and, often, right ventricular dilatation accompanied by normal LV wall thickness are the hallmarks of dilated cardiomyopathy. CLINICAL FEATURES As a result of systolic pump failure, the patient presents with signs and symptoms of heart failure: dyspnea on exertion, orthopnea, par oxysmal nocturnal dyspnea, bibasilar rales, and dependent edema. Depressed ventricular contractile function and dilatation may result in the formation of mural thrombi, and the patient may develop signs of peripheral embolization (e.g., an acute neurologic deficit, flank pain, and hematuria or a pulseless, cyanotic extremity). Chest pain, if present, is felt to be due to limited coronary vascular reserve rather than atherosclerotic coronary artery disease, but the cause cannot be distinguished clinically. Murmurs may be heard during auscultation but do not necessarily indicate primary valvular disease. Annular dilatation and displace ment of the papillary muscles of the atrioventricular valves inhibit complete valve closure. Holosystolic mitral or tricuspid regurgitant murmurs are frequently heard at the apex or lower left sternal border. An apical diastolic rumble may be heard and is due either to accen tuated, early diastolic atrial-to-ventricular flow (the result of mitral regurgitation and left atrial overload) or to a loud summation gallop. The liver will be enlarged and pulsatile if tricuspid insufficiency is significant. DIAGNOSIS The diagnosis may be suspected in patients with typical clinical history, physical exam, and radiographic and ECG findings, but the diagnosis is typically made at follow-up with echocardiography and additional testing as indicated by individual characteristics. 4,5 The chest radiograph invariably shows an enlarged cardiac silhouette and increased cardiothoracic ratio. Biventricular enlargement is common. Evidence of pulmonary venous hypertension (“cephalization” of flow and enlarged hila) is also frequent and may serve to differentiate cardiac enlargement due to myocardial failure from that due to a large pericardial effusion. The ECG is almost always abnormal. LV hypertrophy and left atrial enlargement are the most common findings. Q or QS waves and poor R-wave progression across the anterior precordium may produce a pseudoinfarction pattern.
ntiate cardiac enlargement due to myocardial failure from that due to a large pericardial effusion. The ECG is almost always abnormal. LV hypertrophy and left atrial enlargement are the most common findings. Q or QS waves and poor R-wave progression across the anterior precordium may produce a pseudoinfarction pattern. Atrial fibrillation and ventricular ectopy are common rhythm disturbances. Echocardiographic studies in a symptomatic patient demonstrate a decreased ejection fraction, increased systolic and diastolic volumes, and ventricular and atrial enlargement. Echocardiography is indicated when the cause of heart failure is uncertain, to exclude known causes of heart failure that may be correctable (e.g., pericardial effusion or valvular disease), to estimate ejection fraction, and to rule out other potential complications (e.g., mural thrombi) that may be amenable to therapy. The acuity of the patient’s presentation determines the urgency of echocardiography. TREATMENT AND DISPOSITION For the treatment of acute decompensated heart failure, see Chapter 53, “ Acute Heart Failure. ” Chronic therapy may include diuretics and digoxin, but these drugs do not appear to improve survival rates. 6 Guidelines from the American College of Cardiology for the management of heart failure (and other cardiovascular disorders) are available online at https://www.acc.org/guidelines. The use of angiotensin-converting enzyme inhibitors and b-blockers, specifically carvedilol and metoprolol, improves survival in patients with dilated cardiomyopathy and heart failure. 6 Selected patients may benefit from cardiac resynchronization therapy.5 Patients with complex ventricular ectopy who are found to be at risk for sudden cardiac death may benefit from amiodarone therapy or an implantable cardioverter-defibrillator. 5 Implantable cardioverterdefibrillator placement for primary prevention of sudden cardiac death is not decided solely on ejection fraction, but also by consideration of family history of dilated cardiomyopathy, sudden cardiac death, and cardiac MRI. Patients with a known dilated cardiomyopathy and chronic heart failure may present to the ED with a mild to moderate worsening of symptoms. 7 If the cause is noncompliance with medical therapy or diet, ED treatment with nitrates, IV diuretics, reinstitution of pre scribed medications, patient counseling, and timely referral to the primary care physician are appropriate. However, life-threatening causes of acute exacerbations, such as cardiac ischemia, should be considered before assuming benign causes. 7 Acutely symptomatic patients require hospitalization for definitive diagnosis and manage ment. Important subsets of patients with dilated cardiomyopathy are treated with LV assist devices while awaiting heart transplantation or as destination therapy. 8,9 Principles of patient assessment and manage ment and device complications are described in the Left Ventricular Assist Devices box. MYOCARDITIS (INFLAMMATORY CARDIOMYOPATHY) PATHOPHYSIOLOGY Myocarditis is a common cause of dilated cardiomyopathy but is dis cussed separately to highlight its acute presentation and individual therapy. Myocarditis is inflammation of the heart muscle and is most frequently characterized pathologically by focal infiltration of the myo cardium by lymphocytes, plasma cells, and histiocytes. Varying amounts of myocytolysis and destruction of the interstitial reticulin network are also seen. 10 Because many episodes are mild, they do not always come to medical attention. Table 55-4 lists some common infectious causes of myocarditis. Myocarditis may be accompanied by pericarditis.
sma cells, and histiocytes. Varying amounts of myocytolysis and destruction of the interstitial reticulin network are also seen. 10 Because many episodes are mild, they do not always come to medical attention. Table 55-4 lists some common infectious causes of myocarditis. Myocarditis may be accompanied by pericarditis. TABLE 55-4 Common Infectious Causes of Myocarditis Viral Agents Bacteria Coxsackie B virus Echovirus Influenza virus Parainfluenza virus Epstein-Barr virus Hepatitis B virus Human immunodeficiency virus Corynebacterium diphtheriae Neisseria meningitidis Mycoplasma pneumoniae β-Hemolytic streptococci (rheumatic fever) Lyme disease Tintinalli_Sec07_p0329-0424.indd 381 8/2/19 6:42 PM
Bacteria Coxsackie B virus Echovirus Influenza virus Parainfluenza virus Epstein-Barr virus Hepatitis B virus Human immunodeficiency virus Corynebacterium diphtheriae Neisseria meningitidis Mycoplasma pneumoniae β-Hemolytic streptococci (rheumatic fever) Lyme disease Tintinalli_Sec07_p0329-0424.indd 381 8/2/19 6:42 PM 382 SECTION 7: Cardiovascular Disease LEFT VENTRICULAR ASSIST DEVICES (See Video: Left Ventricular Assist Device) Left ventricular assist devices (LVADs) were originally designed as a bridge to transplant in end-stage heart failure patients but offer long-term quality of life improvement for patients who are not candidates for transplant (destination therapy). LVADs augment left ventricular output in patients with severe cardiomyopathy. There are several models of LVADs in current use that share many similar features. In all LVADs, the implanted pump transfers blood from the apex of the left ventricle to the proximal aorta ( Figure 1). The pump is powered by an external power source (battery or bedside unit), which is connected to a controller. Both the battery and controller reside outside of the body and can be carried or worn by the patient. The controller drives the pump through a driveline, which connects the implanted pump to the external controller through a surgical incision in the abdominal wall. Most contemporary LVADs use pumps that drive blood through a continuous-flow mechanism (e.g., axial or centrifugal flow), maintaining a normal mean arterial blood pres sure in the absence of a palpable pulse. However, many patients may still retain some cardiac contractility; in these individuals, the LVAD serves to assist (and not replace) normal physi ologic cardiac output, and a pulse may be present. Because the LVAD can (in some patients) maintain systemic perfusion even with minimal cardiac function, an LVAD patient can sometimes be clinically stable even in the setting of ventricular fibrillation. LVAD patients still rely upon reasonable right ventricular function to pump blood to the lungs. Patients and families are thoroughly trained on the management of the LVAD and its complications, and they should be involved during patient assessment and management. 8 It is important to call the patient’s LVAD coordinator as soon as possible to assist with management decisions; this information should be present in the patient’s travel bag, along with a spare controller and batteries. CLINICAL FEATURES LVAD patients should have a normal mean arterial pressure of approximately 65 to 90 mm Hg. Blood pressure can be assessed by a mechanical cuff or by Doppler US. If using a Doppler, remember that blood flow has to be continuous and not pulsatile. When auscultating the heart, the continuous whirr of the pump is heard. The ECG should have discernible QRS complexes (Figure 2). The LVAD is visible on a chest radiograph ( Figure 3). Bedside US can be used to assess right ventricular function and to evaluate for pericardial effusion/tamponade. Plain imaging and CT scans are safe, but MRIs are contraindicated. THE HEMODYNAMICALLY UNSTABLE LVAD PATIENT 9 CAN ONE PERFORM CHEST COMPRESSIONS ON AN LVAD PATIENT? Chest compressions can potentially dislodge the LVAD from the heart and aorta, causing left ventricular rupture and intractable hemorrhage. Evaluate for causes of pump failure or lack of perfusion first. Avoid chest compressions if at all possible unless absolutely necessary; use your clinical judgment. Immediately auscultate the precordium to hear an audible “whirr, ” which indicates that the pump is functioning. If nothing is heard, search for a cause of mechanical LVAD failure. With the help of family if needed, check and/or change the batteries and/or controller. Do not disconnect anything.
your clinical judgment. Immediately auscultate the precordium to hear an audible “whirr, ” which indicates that the pump is functioning. If nothing is heard, search for a cause of mechanical LVAD failure. With the help of family if needed, check and/or change the batteries and/or controller. Do not disconnect anything. If unable to restart the LVAD, start CPR with special attention to proper positioning. Avoid excessively deep compressions. If the pump is audible and functioning, obtain a blood pressure (by automatic cuff or manual Doppler) and place the patient on a cardiac monitor and continuous pulse oximetry. If the LVAD model does not provide pulsatile flow, it is difficult to obtain a reading by pulse oximetry. For hypotension or low-perfusion states (mental status, skin temperature/color, capil lary refill, etc.), give a small bolus of normal saline because LVADs are preload dependent. Assess for bleeding (most common reason for ED visit), especially from GI hemorrhage, due to either an acquired von Willebrand disease, supratherapeutic anticoagulation, or a GI arteriovenous malformation. If hypotension persists despite adequate fluid resuscitation or in the presence of right ventricular failure or LVAD malfunction, initiate IV inotropes. Dopamine and dobutamine are reasonable first-line inotropes. Obtain an ECG to rule out right ventricular myocardial infarction or strain. Obtain standard laboratory studies as clinically indicated. Bedside US can assess for right ventricular dilatation or failure. If there is right ventricular strain, consider pulmonary hypertension or pulmonary embolism. Give heparin if pulmonary embolism or device thrombosis is suspected and bleeding has been excluded. Consider tissue plasminogen activator for pump thrombosis, especially if the patient is decompensating and peri-code. Ventricular fibrillation or ventricular tachycardia in an unstable patient requires defibrillation/cardioversion using standard advanced cardiac life support energy recommendations. Do not place defibrillator pads over the driveline. If the patient is clinically stable, give amiodarone according to advanced cardiac life support protocols. MEDICAL COMPLICATIONS Medical complications include anemia, bleeding, thromboembolism, or infection. Anemia can be caused by hemolysis (erythrocyte destruction from the pump) or bleeding. LVAD patients are typically anticoagulated with warfarin to an INR target of 2 to 3. Bleeding and coagulopathy are investigated and treated with standard measures. LVAD patients are also at risk for thromboembolism, such as pulmonary embolism, stroke, and mesenteric ischemia, especially in the setting of suboptimal anticoagulation. Heparin is safe and indicated for such events once bleeding has been ruled out. Infection is a common complication, especially at the driveline exit site. Treat sepsis with volume resuscitation, blood cultures, and antibiotics. FIGURE 2. ECG of a patient with a left ventricular assist device. QRS is evident, and baseline shows some electrical interference from the pump. [ECG used with permission of Daniel Renner, MD.] FIGURE 3. Posteroanterior chest radiograph of a patient with a left ventricular assist device and an implantable defibrillator. The outflow conduit to the proximal aorta is not radiographically visible. [Image used with permission of Daniel Renner, MD.] Battery Controller unit Driveline Pump FIGURE 1. A left ventricular assist device carries blood from the left ventricle to the aorta. Tintinalli_Sec07_p0329-0424.indd 382 8/2/19 6:42 PM
illator. The outflow conduit to the proximal aorta is not radiographically visible. [Image used with permission of Daniel Renner, MD.] Battery Controller unit Driveline Pump FIGURE 1. A left ventricular assist device carries blood from the left ventricle to the aorta. Tintinalli_Sec07_p0329-0424.indd 382 8/2/19 6:42 PM CHAPTER 55: Cardiomyopathies and Pericardial Disease 383 CLINICAL FEATURES Fever, myalgias, headache, and sinus tachycardia, often out of propor tion with fever, are common signs and symptoms. Heart failure develops in severe cases. With less extensive myocardial involvement, the clinical manifestations of systemic illness (fever, myalgias, headache, and rigors) may overshadow clinical signs of myocardial dysfunction, leaving the diagnosis unsuspected. Retrosternal or precordial angina-type chest pain may occur and is usually due to pericardial inflammation (myopericarditis). A pericardial friction rub may be heard. DIAGNOSIS The gold standard for diagnosis of myocarditis is endocardial biopsy, but this invasive modality is uncommonly used. 12 The diagnosis is more commonly made clinically based on symptoms with supportive testing. The chest radiograph is usually normal or nondiagnostic. Cardiomegaly and pulmonary venous hypertension or pulmonary edema are pres ent with severe disease. ECG changes include nonspecific ST-T–wave changes, ST-segment elevation or PR depression from associated peri carditis, atrioventricular block, and QRS interval prolongation. Troponin or B-type natriuretic peptide may be elevated. 13 Echocardiographic studies are also nonspecific, with myocardial depression and wall motion abnormalities in severe cases. Newer imaging modalities include nuclear imaging with positron emission tomography and cardiac MRI. TREATMENT AND DISPOSITION Admission is usually indicated in all cases to monitor progression of disease. Treatment for idiopathic or viral myocarditis is supportive. Antibiotics are needed for myocarditis complicating rheumatic fever, diphtheria, or meningococcemia. Immunosuppressive therapy (e.g., prednisone, azathioprine, and others) may be of value in selected patients, but large trials have not consistently demonstrated benefit. Immunosuppressive therapy is usually reserved for more severe cases and is rarely begun in the ED. Although most patients have a good longterm prognosis, those with fulminant myocarditis have a worse outcome and worse LV function at follow-up. CARDIOMYOPATHIES WITH DIASTOLIC DYSFUNCTION HYPERTROPHIC CARDIOMYOPATHY EPIDEMIOLOGY AND PATHOPHYSIOLOGY Hypertrophic cardiomyopathy is now generally defined as “a disease state characterized by unexplained LV hypertrophy associated with nondilated ventricular chambers is the absence of another cardiac or systemic disease that itself would be capable of producing the magnitude of hypertrophy evident in a given patient. ” 16 The echocardiographic hallmark of the disease is LV wall thickening, usually >15 mm. Cardiovascular magnetic resonance is also useful for diagnosis. 17 Additional echocardiographic findings that might be observed include asymmetric septal hypertrophy and systolic anterior motion. The disorder is usually familial, with autosomal dominant inheri tance, or it can occur sporadically. There is no apparent sex or ethnic predilection. Hypertrophic cardiomyopathy is a clinically and geneti cally heterogeneous disease associated with more than 1500 mutations in more than 11 major genes. 18 Particular genotypes have more rapidly progressive courses. More benign genotypes may be associated with substantial risk of stroke and mortality in the setting of atrial fibrillation. The prevalence in the general population is approximately 1 in 500.
iated with more than 1500 mutations in more than 11 major genes. 18 Particular genotypes have more rapidly progressive courses. More benign genotypes may be associated with substantial risk of stroke and mortality in the setting of atrial fibrillation. The prevalence in the general population is approximately 1 in 500. The annual mortality rate in the overall hypertrophic cardiomyopathy population is <1% per annum. Hemodynamically, hypertrophic cardiomyopathy is characterized by abnormal LV diastolic function due to reduced compliance of the hypertrophied left ventricle. Decreased compliance is reflected by an increase in LV filling pressure. Cardiac output, ejection fraction, and end-systolic volumes are usually normal. Most clinical symptoms are the result of impaired diastolic relaxation and restricted LV filling. CLINICAL FEATURES Dyspnea on exertion is the most frequent initial complaint and is due to exercise-induced sinus tachycardia, which results in an abrupt elevation of LV diastolic pressure and pulmonary venous hypertension due to decreased LV filling time. Additional symptoms include chest pain, palpitations, and syncope. A family history of death due to cardiac disease is not uncommon. Chest pain in hypertrophic cardiomyopathy patients is due to an imbalance between the oxygen demand of the hypertrophied left ventricle and the available myocardial blood flow. 16 In older patients, associated atherosclerotic coronary artery disease may further limit myocardial perfusion. Precordial or retrosternal chest discomfort in hypertrophic cardiomyopathy may mimic angina pectoris or may be “atypical. ” Response to nitroglycerin is poor and highly variable. The hypertrophic cardiomyopathy patient may be aware of forceful ventricular contraction and complain of an abnormal heartbeat or “palpitations. ” Atrial fibrillation is poorly tolerated because of the increased importance of the atrial contribution to LV filling. Jugular venous pressure is usually not elevated. However, a prominent a (atrial) wave may be noted on close inspection of the neck veins. The upstroke of the carotid arterial pulse is rapid and frequently biphasic or bifid (pulsus bisferiens). The apical impulse is sustained and hyperdy namic, and a presystolic lift is common. The first and second heart sounds are usually normal, with an S 4 heard in most patients. A systolic ejection murmur may occur and is heard best at the lower left sternal border or at the apex, and rarely radiates to the carotid arteries. Easily performed bedside maneuvers can be used to increase the intensity and duration of the murmur ( Table 55-5). Interventions that decrease LV filling and the distending pressure in the LV outflow tract or that increase the force of myocardial contraction accentuate the murmur of hypertrophic cardiomyopathy. Such interventions include standing and the strain phase of the Valsalva maneuver. Maneuvers that increase LV filling (squatting, passive leg elevation, and hand grip) decrease the murmur. The murmurs of hypertrophic cardiomyopathy and mitral valve prolapse, when associated with mur mur, are similar and are compared in Table 55-5. DIAGNOSIS The diagnosis may be suspected in the ED based on symptoms, family history, and physical exam findings and confirmed with cardiac MRI or echocardiography. The chest radiograph is usually normal or nonspecific. The resting ECG is nonspecific in most, often demonstrating LV hypertrophy and left atrial enlargement. Q waves >0.3 mV , termed septal Q waves, may be seen in anterior, lateral, or inferior leads. Q waves may mimic those seen after myocardial infarction (pseudoinfarction pattern). The polarity of the T wave can differentiate between hyper trophic cardiomyopathy septal Q waves and Q waves due to myocardial infarction.
t. Q waves >0.3 mV , termed septal Q waves, may be seen in anterior, lateral, or inferior leads. Q waves may mimic those seen after myocardial infarction (pseudoinfarction pattern). The polarity of the T wave can differentiate between hyper trophic cardiomyopathy septal Q waves and Q waves due to myocardial infarction. Upright T waves in those leads with QS or QR complexes are usually found in hypertrophic cardiomyopathy (Figure 55-1), whereas TABLE 55-5 Effect of Bedside Interventions on the Murmur of Hypertrophic Cardiomyopathy Compared to Mitral Valve Prolapse Intervention Hypertrophic Cardiomyopathy Mitral Valve Prolapse Valsalva maneuver (strain phase) Murmur increased Click closer to S 1, murmur increased Standing after squatting Murmur increased Click closer to S1, murmur increased Passive leg elevation in supine patient Murmur decreased Click closer to S 2, murmur decreased Hand grip Murmur decreased Click closer to S1, murmur increased Squatting Murmur decreased Click closer to S2, murmur decreased Tintinalli_Sec07_p0329-0424.indd 383 8/2/19 6:42 PM
ncreased Click closer to S1, murmur increased Passive leg elevation in supine patient Murmur decreased Click closer to S 2, murmur decreased Hand grip Murmur decreased Click closer to S1, murmur increased Squatting Murmur decreased Click closer to S2, murmur decreased Tintinalli_Sec07_p0329-0424.indd 383 8/2/19 6:42 PM 384 SECTION 7: Cardiovascular Disease T-wave inversion in such leads is highly suggestive of ischemic heart disease. Echocardiography plays a substantial role in the diagnosis of hyper trophic cardiomyopathy, in the correlation of the auscultatory and hemodynamic events with LV anatomic changes, and in defining inheritance patterns. Cardiac MRI is recommended when echocardiography is inconclusive in patients clinically suspected of having the disease and is also helpful in risk stratification. TREATMENT AND DISPOSITION The majority of patients with hypertrophic cardiomyopathy who seek medical care typically do so because of declining exercise tolerance, chest pain, or syncope. The patient who presents complaining of exercise intolerance or chest pain in whom the typical murmur of hypertrophic cardiomyopathy is heard should be referred for echocardiographic evaluation after other causes have been considered. Syncope in patients with hypertrophic cardiomyopathy typically occurs during or imme diately after exercise. If hypertrophic cardiomyopathy is suspected in a patient with syncope, hospitalization is indicated. 16,19 Syncope in patients with hypertrophic cardiomyopathy may presage sudden cardiac death. The diagnostic evaluation is extensive and includes echocardiographic studies as well as extended cardiac monitoring, exercise stress testing to assess blood pressure response, and tilt testing. Beta-blockers are the mainstay of therapy for symptomatic patients. 16,20 RESTRICTIVE CARDIOMYOPATHY EPIDEMIOLOGY AND PATHOPHYSIOLOGY Restrictive cardiomyopathy is most commonly idiopathic, but may be of genetic origin with autosomal transmission and due to mutations in cardiac sarcomere protein genes. 21 A restrictive cardiomyopathy may also result from systemic disorders that cause infiltration of the myocardium, resulting in replacement or displacement of normal myocardium. Sys temic diseases that may be associated with a restrictive cardiomyopathy include amyloidosis, sarcoidosis, hemochromatosis, progressive systemic sclerosis (scleroderma), carcinoid heart disease, endomyocardial fibrosis, and hypereosinophilic syndrome. Restrictive cardiomyopathy is characterized by “restricted” ven tricular filling, with normal or decreased diastolic volume of one or both ventricles. Systolic function is usually normal, and ventricular wall thickness may be normal or increased, depending on the under lying cause. The restrictive cardiomyopathies may account for up to 15% of cases of heart failure with preserved ejection fraction. The hemodynamic hallmarks include (1) elevated LV and right ventricu lar end-diastolic pressure, (2) normal LV systolic function (ejection fraction >50%), and (3) a marked decrease followed by a rapid rise and plateau in early diastolic ventricular pressure observed during invasive hemodynamic assessment. The rapid rise and abrupt plateau in the early diastolic ventricular pressure trace produce a characteristic “square root sign” or “dip-and-plateau” filling pattern due to increased myocardial stiffness. This pattern is not diagnostic, however, and may be seen in constrictive pericarditis, with which restrictive cardiomyop athy is commonly confused. Differentiation between the two is critical because constrictive pericarditis can be cured surgically. The diagnosis of restrictive cardiomyopathy should be considered in a patient presenting with congestive heart failure but no evidence of cardiomegaly or systolic dysfunction.
ive cardiomyop athy is commonly confused. Differentiation between the two is critical because constrictive pericarditis can be cured surgically. The diagnosis of restrictive cardiomyopathy should be considered in a patient presenting with congestive heart failure but no evidence of cardiomegaly or systolic dysfunction. CLINICAL FEATURES AND DIAGNOSIS Symptoms are typical of heart failure and include dyspnea, orthopnea, and pedal edema. Right-sided heart failure may predominate and results in hepatomegaly, right upper quadrant pain, and ascites. Chest pain is uncommon, except in amyloidosis. Findings on physical examination depend on the stage or severity of myocardial involvement. An S 3 and an S 4 are often heard. Pulmonary rales, jugular venous distention, Kussmaul sign (jugular venous pulse rises during inspiration rather than falling), hepatomegaly, pedal edema, and ascites are also typical findings. On chest radiograph, there may be signs of heart failure but a normal heart size. Chamber enlargement due to wall thickening, but not dilatation, and nonspecific ST-T–wave changes are usually noted on the ECG. Cardiac conduction disturbances are common in amyloidosis and sarcoidosis. Atrial fibrillation may occur in the setting of atrial enlargement. Low-voltage QRS complexes (QRS amplitude <0.7 mV) are frequently described in patients with restrictive cardiomyopathy secondary to amyloidosis and hemochro matosis. The differential diagnosis includes constrictive pericarditis or diastolic LV dysfunction (most commonly due to ischemic heart disease, hypertension, or age-related changes in ventricular diastolic compli ance). Doppler echocardiographic studies, cardiac MRI, and cardiac catheterization with hemodynamic assessment are often required for specific diagnosis. TREATMENT AND DISPOSITION CT and MRI of the heart can differentiate constrictive pericarditis from restrictive cardiomyopathy. 22 Correct diagnosis is important because constrictive pericarditis can be surgically corrected, and diastolic LV dysfunction usually responds well to beta-blockers or calcium channel blockers. The medical management of restrictive cardiomyopathy is less effective and symptom directed (diuretics and angiotensin-converting enzyme inhibitors) unless due to sarcoidosis (corticosteroid therapy) or hemochromatosis (chelation therapy). The need for admission is usually determined by the severity of symptoms and the availability of diagnostics. Genetic testing is often recommended. PERICARDIAL DISEASE ANATOMY AND PATHOPHYSIOLOGY The pericardium consists of a serous or loose fibrous membrane (visceral pericardium) overlying the epicardium and a dense collagenous sac (parietal pericardium) surrounding the heart. The space between the visceral and parietal pericardium may normally contain up to 50 mL of fluid. 23 Because its layers are serosal surfaces and because of its proximity and attachments to other structures, the pericardium may be involved in a number of disease processes (Table 55-6). In this section, the clinical manifestations and evaluation of acute and constrictive pericarditis and nontraumatic cardiac tamponade are discussed. ACUTE PERICARDITIS CLINICAL FEATURES The most common symptom of acute pericarditis is sharp or stabbing precordial or retrosternal chest pain. Pain may be of sudden or gradual onset; radiate to the back, neck, left shoulder, or arm; and aggravated by inspiration or movement. Referral of pain to the left trapezial ridge FIGURE 55-1. Hypertrophic cardiomyopathy ECG findings. Deep S-wave voltage (28 mm S in V 2, large arrow) signifies left ventricular hypertrophy, and narrow septal Q waves in V5 and V6 (arrowheads) are noted.
, left shoulder, or arm; and aggravated by inspiration or movement. Referral of pain to the left trapezial ridge FIGURE 55-1. Hypertrophic cardiomyopathy ECG findings. Deep S-wave voltage (28 mm S in V 2, large arrow) signifies left ventricular hypertrophy, and narrow septal Q waves in V5 and V6 (arrowheads) are noted. T waves are upright in the leads with the septal Q waves, with upright T waves in leads V 5 and V6, typical of hypertrophic cardiomyopathy. This patient also has atrial flutter with 2:1 block. The additional P waves appear in the ST segments ( small arrows). [Reproduced with permission from Knoop KJ, Stack LB, Storrow AB, Thurman RJ (eds): The Atlas of Emergency Medicine, 3rd ed. New York: McGraw-Hill; 2010; Fig 23.40B.] Tintinalli_Sec07_p0329-0424.indd 384 8/2/19 6:42 PM
o has atrial flutter with 2:1 block. The additional P waves appear in the ST segments ( small arrows). [Reproduced with permission from Knoop KJ, Stack LB, Storrow AB, Thurman RJ (eds): The Atlas of Emergency Medicine, 3rd ed. New York: McGraw-Hill; 2010; Fig 23.40B.] Tintinalli_Sec07_p0329-0424.indd 384 8/2/19 6:42 PM CHAPTER 55: Cardiomyopathies and Pericardial Disease 385 (due to inflammation of the joining diaphragmatic pleura) is a particu lar distinguishing feature. Chest pain due to acute pericarditis may be aggravated by inspiration or movement. Typically, chest pain is most severe when the patient is supine and is relieved when the patient sits up and leans forward. Associated symptoms may include fever, dyspnea due to accentuated pain with inspiration, and dysphagia from irritation of the esophagus by the posterior pericardium. 24,25 A pericardial friction rub is the most common and important physical finding in pericarditis, but may be difficult to appreciate in a noisy ED. It is best heard with the diaphragm of the stethoscope at the lower left sternal border or apex when the patient is sitting and leaning for ward. It may be audible only during a certain phase of respiration and characteristically is intermittent. A pericardial friction rub is most often triphasic, with a systolic component due to ventricular contraction, an early diastolic component during the early phase of ventricular filling, and a presystolic component synchronous with atrial systole. It is less commonly biphasic, with a systolic component with either an early diastolic or presystolic component. A monophasic rub is less common but is most often systolic. DIAGNOSIS The ECG is the most important tool for initial diagnosis. Serial ECG changes during acute pericarditis and its convalescence are characterized by four stages (Table 55-7 and Figure 55-2A and B). If a large pericardial effusion develops during the course of acute pericarditis, low-voltage QRS complexes and electrical alternans may be evident. Pericardial fluid attenuates myocardial electrical signals, and the pendular motion of the heart within the fluid-filled pericardial space results in electrical alternans (see Figure 55-5 in the “Nontraumatic Cardiac Tamponade” section of this chapter). Although serial ECG tracings are of diagnostic value in acute peri carditis, sequential ECG assessment is not a diagnostic luxury afforded the emergency physician. The classic ECG findings in acute pericarditis include diffuse ST-segment elevation (most pronounced in the lateral precordial leads), PR-segment depression, and ST-segment depres sion in lead aVR. ST-segment elevation is due to the inflammation of the epimyocardium. Classic ECG changes are not observed in uremic pericarditis because the epicardium is not involved in the inflammatory process. The ST-segment/T-wave amplitude ratio in leads V 6, or I can differentiate pericarditis from early repolarization.26 Using the end of the PR segment as a baseline, or 0 mV , the amplitude or height of the ST segment at its onset (the J point) is measured in V 6 or lead I and recorded in millivolts. The height of the T wave in the same lead is measured from the baseline to the T-wave peak. If the ratio of ST amplitude (in millivolts) to T-wave amplitude (in millivolts) is >0.25, acute pericardi tis is likely (Figure 55-2), and if the ratio is <0.25, acute pericarditis is unlikely. Sensitivity at an ST/T ratio of >0.25 for acute pericarditis is over 85%, and the specificity is over 80% (positive likelihood ratio of about 4 and negative likelihood ratio of about 0.2). Pericarditis alone does not cause significant cardiac rhythm disturbances. Chest radiographs are of limited value.
tis is unlikely. Sensitivity at an ST/T ratio of >0.25 for acute pericarditis is over 85%, and the specificity is over 80% (positive likelihood ratio of about 4 and negative likelihood ratio of about 0.2). Pericarditis alone does not cause significant cardiac rhythm disturbances. Chest radiographs are of limited value. The cardiac silhouette may be of normal size and contour in acute pericarditis and, in some instances, the setting of cardiac tamponade. If previous chest radiographs are available for comparison, a recent increase in the size of the cardiac silhouette or an increase in the cardiothoracic ratio without radiographic evidence of pulmonary venous hypertension can distinguish an expanding pericardial effusion from left heart failure. The “epicardial fat pad sign” is rarely seen on the lateral chest radiograph and has been reported in only 15% of cases of acute pericarditis during fluoroscopy with image intensification. If acute pericarditis is suspected on the basis of history, physical examination, or ECG, a chest radiograph may help establish an underlying cause, such as neoplasm or infection. Echocardiography is the procedure of choice for the detection and confirmation. Normally, the pericardial sac is only a “potential” space, and the myocardium is echocardiographically in direct contact with surrounding thoracic structures. The anterior right ventricular wall is in contact with the chest wall, and the posterior LV wall is in contact with the posterior pericardium and adjacent pleura. When a pericardial effusion is present, the pericardial space fills with echofree fluid ( Figure 55-3). For serial follow-up of patients with acute pericarditis and a pericardial effusion, CT and cardiac MRI may be complementary. Echocardiographically, a separation is seen between the right ven tricle and the chest wall and between the left ventricle and the poste rior pericardium. Quantitation of the size of the effusion is arbitrary and is determined by where the hypoechoic space is seen (anterior or posterior) and when in the cardiac cycle it occurs. For example, when a hypoechoic space is seen only posteriorly and only during systole, a small effusion is said to be present. The sensitivity of CT for detecting pericardial effusion is similar to that of echocardiography (Figure 55-4). Suggested laboratory studies are listed in Table 55-8. Serum tro ponins may be elevated in acute pericarditis due to associated myocarditis. TREATMENT AND DISPOSITION Treatment of pericarditis depends on the cause. 24,25 Most patients with idiopathic or presumed viral pericarditis have a benign course lasting 1 to 2 weeks. Symptoms respond well to NSAIDs administered for 7 days to 3 weeks. However, this class of drugs should be used with caution due to known risks of acute coronary syndromes. 28 Corticosteroid treatment can alternatively be used for patients with poor NSAID tolerance, contraindication, or failure of NSAIDs. Colchicine, 0.5 milligram orally twice a day, may be a beneficial adjuvant and may prevent recurrent episodes and symptoms persistent at 72 hours. 24 Hospitalization is not necessary in most cases. Indicators of a poor prognosis include tem perature >38°C (100.4°F), subacute onset over weeks, immunosuppression, history of oral anticoagulant use, associated myocarditis (elevated cardiac biomarkers, symptoms of heart failure), failure to respond to therapy with NSAIDs after 1 week of therapy, a large pericardial effu sion (an echo-free space >20 mm), or cardiac tamponade.
(100.4°F), subacute onset over weeks, immunosuppression, history of oral anticoagulant use, associated myocarditis (elevated cardiac biomarkers, symptoms of heart failure), failure to respond to therapy with NSAIDs after 1 week of therapy, a large pericardial effu sion (an echo-free space >20 mm), or cardiac tamponade. 25 In general, patients with these risk factors or with an enlarged cardiac silhouette TABLE 55-7 Serial ECG Changes of Acute Pericarditis Stage PR Segment ST Segment T Wave 1 (acute) Depression, especially in II, aVF, and V 4–V 6 Elevation, especially in I, 5, and V6; ST amplitude: T-wave amplitude >0.25 — 2 Isoelectric or depressed Returns to isoelectric line Amplitude decreases, inversion rare 3 Isoelectric or depressed Isoelectric T-wave inversion, especially in I, V 5, and V6 4 Isoelectric Isoelectric Normal TABLE 55-6 Common Causes of Acute Pericarditis • Idiopathic • Infectious • Viral (coxsackie virus, echovirus, human immunodeficiency virus) • Bacterial (especially Staphylococcus, Streptococcus pneumoniae, β-hemolytic strepto cocci [acute rheumatic fever], Mycobacterium tuberculosis) • Fungal (especially Histoplasma capsulatum) • Malignancy (leukemia, lymphoma, metastatic breast and lung carcinoma, melanoma) • Drug induced (procainamide, hydralazine) • Systemic rheumatic diseases (systemic lupus erythematosus, rheumatoid arthritis, scleroderma, polyarteritis nodosa, dermatomyositis) • Radiation induced • Postmyocardial infarction (Dressler’s syndrome) • Uremia • Myxedema Tintinalli_Sec07_p0329-0424.indd 385 8/2/19 6:42 PM
duced (procainamide, hydralazine) • Systemic rheumatic diseases (systemic lupus erythematosus, rheumatoid arthritis, scleroderma, polyarteritis nodosa, dermatomyositis) • Radiation induced • Postmyocardial infarction (Dressler’s syndrome) • Uremia • Myxedema Tintinalli_Sec07_p0329-0424.indd 385 8/2/19 6:42 PM 386 SECTION 7: Cardiovascular Disease FIGURE 55-2. This series of three ECGs shows the typical progression of changes associated with acute pericarditis. A. In stage I pericarditis, the ECG shows diffuse ST-segment elevation and PR depression in leads I, II, III, and aVF. The ST-segment to T-wave amplitude ratio measured in V 6 is 2 mm/4 mm, or 0.50, thus meeting criteria for pericarditis rather than early repolarization (see the text under “Diagnosis”). B. In stage II pericarditis, ST segments are returning toward the isoelectric point in most leads in which they had been elevated. C. In stage III pericarditis, we see resolution of ST changes and the appearance of diffuse T-wave inversion. These evolutionary changes are typical of and diagnostic for pericarditis and usually occur over several weeks. Tintinalli_Sec07_p0329-0424.indd 386 8/2/19 6:42 PM
in most leads in which they had been elevated. C. In stage III pericarditis, we see resolution of ST changes and the appearance of diffuse T-wave inversion. These evolutionary changes are typical of and diagnostic for pericarditis and usually occur over several weeks. Tintinalli_Sec07_p0329-0424.indd 386 8/2/19 6:42 PM CHAPTER 55: Cardiomyopathies and Pericardial Disease 387 on chest radiograph should be admitted for serial echocardiography to assess changes in effusion size, degree of hemodynamic compromise, and cardiac dysfunction. NONTRAUMATIC CARDIAC TAMPONADE PATHOPHYSIOLOGY An increase in the amount of fluid within the pericardial sac results in an increase in intrapericardial pressure. The normal fibrocollagenous parietal pericardium has elastic properties and stretches to accommo date increases in intrapericardial fluid. The initial portion of the pericardial volume-pressure curve is flat: Relatively large increases in volume result in comparatively small changes in intrapericardial pressure. The curve becomes steeper as the parietal pericardium reaches the limits of its distensibility. 29 If fluid continues to accumulate, intrapericardial pressure rises to a level greater than that of the normal filling pressures of the right heart chambers. When this occurs, ventricular filling is restricted and results in cardiac tamponade. The point at which this occurs is determined by the rate of fluid accumulation, pericardial compliance (a thickened parietal pericardium is less distensible), and intravascular volume (hypovolemia lowers ventricular filling pressure). Common causes of cardiac tamponade in nontrauma patients are listed in Table 55-9. CLINICAL FEATURES Symptoms are nonspecific, and patients most commonly complain of dyspnea at rest and with exertion. Additional symptoms may be due to the underlying disease (e.g., uremia or tuberculous pericarditis). Physical examination may reveal tachycardia and low systolic arterial blood pressure with a narrow pulse pressure. Pulsus paradoxus may also be present. 29 A paradoxical arterial pulse is said to be present when the cardiac rhythm is regular and there are apparent dropped beats in the peripheral pulse during inspiration. There is usually a <10 mm Hg decrease in systolic blood pressure during inspiration in the supine position. A value >10 mm Hg usually separates true tamponade from lesser FIGURE 55-4. This CT scan of the chest shows a large pericardial effusion (pe) predomi nantly posteriorly located in a patient with scleroderma and pericarditis. No pericardial thick ening or calcification was detected. Esophageal (e) dilatation is noted. Cardiac function cannot be evaluated. H = heart; L = liver. [Reprinted with permission from Roldan CA: Connective tissue diseases & the heart, in Crawford MH (ed): Current Diagnosis & Treatment in Cardiology , 3rd ed. Copyright © 2009, The McGraw-Hill Companies, Inc., all rights reserved, Figure 33-5.] A B FIGURE 55-3. A. Pericardial effusion on parasternal long-axis view. Ant Eff = anterior effusion; AV = aortic valve; LA = left atrium; LV = left ventricle; Post Eff = posterior effusion; RV = right ventricle. B. Pericardial effusion (arrows) on parasternal short-axis view. [Reprinted with permission from Reardon RF, Joing SA: Cardiac, in Ma OJ, Mateer JR, Blaivas M (eds): Emergency Ultrasound, 2nd ed.
ior effusion; AV = aortic valve; LA = left atrium; LV = left ventricle; Post Eff = posterior effusion; RV = right ventricle. B. Pericardial effusion (arrows) on parasternal short-axis view. [Reprinted with permission from Reardon RF, Joing SA: Cardiac, in Ma OJ, Mateer JR, Blaivas M (eds): Emergency Ultrasound, 2nd ed. Copyright © 2008, The McGraw-Hill Companies, Inc., all rights reserved, Figure 6-24.] TABLE 55-8 Ancillary Diagnostic Studies in Acute Pericarditis Diagnostic Study Considerations Cardiac markers Indicate myocardial involvement (epimyocarditis) CBC and differential WBC count May suggest infection or leukemia BUN/creatinine May suggest a diagnosis of uremic pericarditis Chest radiograph Infiltrate or mass suggests infection or malignancy as etiology Blood cultures If bacterial infection suspected Serologic studies Antinuclear antibodies, anti-DNA titers, or rheumatoid factor in patients with systemic symptoms Erythrocyte sedimentation rate, C-reactive protein Will not determine specific diagnosis, but can confirm clinical suspicion of pericarditis and can be followed serially to assess response to therapy Acute and convalescent viral antibody titers May suggest viral origin; titers would not be expected to change the course of treatment Thyroid function studies Thyrotoxicosis is a rare cause of pericarditis; hypothyroidism can cause pericardial effusion without the typical ECG changes and symptoms of pericarditis Tintinalli_Sec07_p0329-0424.indd 387 8/2/19 6:42 PM
May suggest viral origin; titers would not be expected to change the course of treatment Thyroid function studies Thyrotoxicosis is a rare cause of pericarditis; hypothyroidism can cause pericardial effusion without the typical ECG changes and symptoms of pericarditis Tintinalli_Sec07_p0329-0424.indd 387 8/2/19 6:42 PM 388 SECTION 7: Cardiovascular Disease degrees of restricted cardiac filling. Pulsus paradoxus is not diagnostic of cardiac tamponade and may be noted in other cardiopulmonary processes. In cardiac tamponade, the neck veins may be distended with an absent “y” descent. The apical impulse is indistinct or tapping in quality. Cardiac auscultation may reveal “distant” or soft heart sounds. Pulmo nary rales are usually absent, and there may be right upper quadrant tenderness from hepatic venous congestion. DIAGNOSIS The chest radiograph may or may not reveal an enlarged cardiac silhouette because this finding depends on the amount of intrapericardial fluid accumulation. The pulmonary vasculature typically appears normal. An epicardial fat pad sign may occasionally be seen within the cardiac silhouette. The ECG usually shows low-voltage QRS complexes (<0.7 mV) and ST-segment elevation (due to the inflammation of the epicardium) with PR-segment depression, as in pericarditis. Electrical alternans (beat-tobeat variation in the amplitude of the P and R waves unrelated to the respiratory cycles; Figure 55-5) is a classic but uncommon finding. Suspect the diagnosis based on the clinical examination and chest radiographs. Echocardiography is the diagnostic test of choice. In addition to a large pericardial fluid volume, typical echocardiographic findings described in cardiac tamponade are right atrial compression, right ventricular diastolic collapse, abnormal respiratory variation in tricuspid and mitral flow velocities, and dilated inferior vena cava with lack of inspiratory collapse. TREATMENT AND DISPOSITION Volume expansion with a bolus of normal saline solution (500 to 1000 mL) will increase intravascular volume, facilitate right heart filling, and increase cardiac output and arterial pressure. However, it is a temporary measure. Pericardiocentesis is necessary for definitive therapy and for specific diagnosis. If there is hemodynamic instability, emergency pericardiocentesis is indicated in the ED. The technique is described in Section 4, “Resus citative Procedures, ” Chapter 34, “Pericardiocentesis. ” (See Video: Pericardiocentesis.) However, pericardiocentesis is optimally performed in the cardiac catheterization laboratory using echocardiographic guidance to avoid cardiac perforation and coronary artery laceration. In addition, fluid samples for culture, cytology, and so on can be obtained in a more controlled setting, and following needle aspiration, a pigtail catheter can be inserted to allow continuous fluid drainage and prevention of reaccumulation. CONSTRICTIVE PERICARDITIS PATHOPHYSIOLOGY Constrictive pericarditis results from pericardial injury and inflamma tion, resulting in fibrous thickening of the layers of the pericardium, which prevents passive diastolic filling of the cardiac chambers. 31 Some causes include postcardiac trauma with intrapericardial hemorrhage, after pericardiotomy (open heart surgery, including coronary revascu larization), in fungal or tuberculous pericarditis, and in chronic renal failure (uremic pericarditis), but in most cases, a specific cause is not determined. CLINICAL FEATURES The symptoms of constrictive pericarditis usually develop gradually and may mimic those of congestive heart failure and restrictive cardiomyopathy. However, clinical signs may occur early if fluid also accumulates within the thickened, noncompliant pericardial sac (effusive constrictive pericarditis).
CLINICAL FEATURES The symptoms of constrictive pericarditis usually develop gradually and may mimic those of congestive heart failure and restrictive cardiomyopathy. However, clinical signs may occur early if fluid also accumulates within the thickened, noncompliant pericardial sac (effusive constrictive pericarditis). Common signs and symptoms include exertional dyspnea, pedal edema, hepatomegaly, and ascites. Examination of the neck veins with the patient at a 45-degree angle from horizontal will reveal jugular venous distention and a rapid “y” descent of the cervical venous pulse. Elevated venous pressure is also seen in congestive heart failure, but a rapid “y” descent is infrequently encountered. The Kussmaul sign (inspiratory neck vein distention) is frequent in constrictive pericarditis but rare in congestive heart failure. A paradoxical pulse is uncommon, and its absence does not exclude constrictive pericarditis. On cardiac auscultation, an early diastolic sound, a pericardial “knock, ” may be heard at the apex 60 to 120 milliseconds after the second heart sound. The pericardial knock sounds like a ventricular gallop, but occurs earlier than the S 3 of congestive heart failure, which it may mimic. The knock is due to accelerated right ventricular inflow in early diastole and early myocardial distention, followed by an abrupt slowing of further ventricular expansion. DIAGNOSIS AND DISPOSITION On the ECG, low-voltage QRS complexes and inverted T waves are common, but there are no specific diagnostic ECG signs. Chest radiographs most commonly demonstrate a normal or slightly enlarged cardiac sil houette, clear lung fields, and little or no evidence of pulmonary venous congestion. Pericardial calcification may be seen. Thoracic CT and MRI may also demonstrate a thickened pericardium. On occasion, two-dimensional echocardiography may demonstrate pericardial thickening and abnormal ventricular septal motion in a patient with suspected constrictive pericarditis. However, its diagnostic utility is much less than that in a patient with acute pericarditis. Doppler echocardiography, cardiac CT, and MRI are preferred. In many instances cardiac catheterization with measurement of intraventricular pressures will be required to confirm the diagnosis. A char acteristic dip and plateau (the “square root sign”) of the right ventricular pressure trace is characteristic of the disease. In cases of significant constriction and impaired ventricular filling, admission for pericardiectomy is the treatment of choice. REFERENCES The complete reference list is available online at www.TintinalliEM.com. FIGURE 55-5. This rhythm strip (lead II, top tracing) and plethysmograph (bottom tracing) were recorded in a patient who presented with dyspnea, hypotension, and clinical and echocardiographic evidence of cardiac tamponade. A paradoxical pulse was noted on palpation of the radial artery. The amplitude of the R waves varies from beat to beat (electri cal alternans). TABLE 55-9 Common Causes of Cardiac Tamponade in Medical (Nontrauma) Patients Cause Approximate Frequency (%) Metastatic malignancy 40 Acute idiopathic pericarditis 15 Uremia 10 Bacterial or tubercular pericarditis 10 Chronic idiopathic pericarditis 10 Hemorrhage (anticoagulant) 5 Other (systemic lupus erythematosus, postradiation, myxedema, etc.) Tintinalli_Sec07_p0329-0424.indd 388 8/2/19 6:42 PM