ECG: Sinus tachycardia, generalized low-voltage QRS complexes with non-speci \201 c ST seg ment and T-wave changes. Electrical alternans, involving the QRS complex, suggests the pres ence of a massive pericardial effusion. Total electrical alternans (P-QRS-T), which is unco mmon, is pathognomonic of cardiac tamponade. Echocardiography: Is diagnostic, showing an ECHO-free zone surrounding the heart. The \202 uid may not be evenly distributed. Diastolic collapse of the right ventricle and right atrium indicate cardiac tamponade. The following features are more common in patients with tuberculous or malignant causes of pericardial effusion: soft tissue density masses, thick ening of the visceral pericardium, and presence of \201 brinous strands. The hallmark of benign, idiopathic effusion is a clear ECHO-free space, whereas malignancy, bacterial infec tion, and haemorrhagic effusions are more likely to have solid components or stranding. PERICARDIAL EFFUSION WITH OR WITHOUT TAMPONADE 463 CXR: Shows a large globular heart, usually with clear lung \201 elds. Cardiac catheterization: Establishes the diagnosis and severity of tamponade. The important \201 ndings are: \200 equilibration of mean right atrial, right ventricular end-diasto lic, and mean capillary wedge pressure rapid \200\230x \200\231 descent on the right atrial pressure waveform \200 pulsus parad oxus. Differential diagnosis: Myocardial infarction and pulmonary embolism. Management \200 When an effusion does not cause haemodynamic impairment and the cause is known (e.g. uraemia, myxoedema), then no further investigations are necessary and the treat ment consists of treating the underlying cause. If the cause is not known, then pericardiocentesis must be considered. Aspiration of the \202 uid helps to establish the nature of the effusion (see b Pericardial \202 uid analys is, p. 476). Cardiac tamponade is a life-threatening condition: urgent pericardial aspiration is necessary (see b pp. 814 \200\2236). Surgical drainage is indicated for haemo pericardium or purulent pericarditis. 464 CHAPTER 9 Pericardial diseases Constrictive pericarditis Etiology: Constrictive pericarditis is usually due to TB. Other c auses are mediastinal irradiation, purulent pericarditis, previous trauma (surgical or non- surgical) with infection of the pericardial space, and, very rarely, viral pericarditis. Pathology: The pericardium becomes a dense mass of \201 brous tissue and this may be calc i \201 ed. This results in encasement of the heart within a non-expansile pericardium. Symptoms: Dyspnoea, oedema and abdominal swelling due to ascites and hepatomegaly. Signs: Small volume pulse and pulsus paradoxus. JVP is always elevated, usually very high w ith prominent \200\230x \200\231 and \200\230y \200\231 descents. A diastolic knock is us ually felt at the left sternal border due to the sudden halting of the ventricles during di astolic \201 lling. The apex beat may be impalpable. Heart sounds are usually soft, and a n early third sound coincident with the diastolic knock is usually heard. In the pulmonary area there is sudden instantaneous widened splitting of the second sound that occurs follow ing the \201 rst heartbeat of inspiration (Vogelpoel \200\223Beck sign). The liver is com monly grossly enlarged, ascites is marked, and peripheral oedema is present. ECG: Is abnormal in virtually every case, but changes are non-speci \201 c. (i.e. generali zed low-voltage QRS complexes, and widespread \202 attening and inversion of T waves). AF is common in the chronic form. CXR: A normal or near-normal cardiac size in the presence of marked venous distension or he art failure is suggestive of constrictive pericarditis or restrictive cardiomyopathy. Peric ardial calci \201 cation is diagnostic but its incidence varies from 5 % to 70 % of cases in different series. Echocardiography: Pericardial thickening may be present. There is a restrictive mitral \201 lling pattern on Doppler, with respiratory variation of > 25 % over the AV valves. Computed tomography (CT) and magnetic resonance imaging (MRI) scan: These techniques demons trate pericardial thickening ( > 5 mm). Cardiac catheterization: This demonstrates elevation and equalization of \201 lling press ures. In the typical case, the difference in \201 lling pressures between the right ventr icle and left ventricle does not exceed 6 mmHg. The right atrial waveform shows rapid \200 \230x \200\231 and \200\230y \200\231 descents, and the mean pressure does not decrease no rmally with inspiration, or may show Kussmaul \200\231s sign. Management: Constrictive pericarditis is treated by surgical removal of the \201 brous co nstrictive tissue (pericardiectomy). CALCIFIC PERICARDITIS WITHOUT CONSTRICTION 465 Effusive-constrictive pericarditis Etiology: This is characteristically encountered in active TB pericarditis, where there are signs of both pericardial effusion or tamponade and constriction. It may also occur in neo plastic, radiation, and septic pericarditis. Clinical presentation: Symptoms are usually those of constriction. Examination reveals puls us paradoxus, raised JVP with prominent \200\230x \200\231 and \200\230y \200\231 descent s. The CXR shows an enlarged cardiac silhouette like that of pericardial effusion. Diagnosis: The clue to diagnosis is persistent signs of constriction following adequate per icardial drainage. Management: Treatment of the underlying cause and pericardial drainage is indicated. Perica rdiectomy is indicated should haemodynamics not improve. Calci \201 c pericarditis without constriction This condition is usually discovered during routine radiological examina- tion, which demonstrates pericardial calci \201 cation. The re are no symptoms and signs of constriction, and the cause is usually unknown. 466 CHAPTER 9 Pericardial diseases Viral pericarditis Clinical presentation: Most patients present with a history of upper res piratory tract infection within the preceding three weeks. The viruses most frequently resp onsible include Coxsackie B, ECHO, mumps, in \202 uenza, and varicella. Pericardial pain, fever, and malaise are typical. The physical examination reveals a pericardial friction rub and/or characteristic changes of acute pericarditis on ECG. Course: In the majority of patients, the illness resolves spontaneously in one to two weeks . In some patients, the illness recurs on at least one occasion in the next few weeks or mo nths, and in 20 % of patients there are multiple recurrences in the ensuing months or years (benign relapsing pericarditis). Diagnosis: It is important to search for an underlying disease (see the box on b Etiology, p. 460) that may require speci \201 c therapy. In most cases of suspected viral pericardit is, special studies for aetiologic agents are not necessary because of the low diagnostic y ield of viral studies and lack of speci \201 c therapy for viral disease. Treatment: NSAIDs are effective in most patients with viral pericarditis. There are no data from randomized controlled trials to guide treatment for relapsing patients who do not res pond to NSAIDs. Corticosteroids (prednisone 1 \200\2231.5 mg/kg for at least 1 month) provi de symptomatic relief in most patients; symptoms recur in many patients when the prednisone dose is reduced. Colchicine (2 mg/day for 1 \200\2232 days, followed by 1 mg/ day) may be effective when NSAIDs and corticosteroids fail to prevent relapses. If patients do not resp ond adequately, azathioprine (75 \200\223100 mg/ day) or cyclophosphamide may be added. Per icardiectomy is indicated only in frequent and highly symptomatic recurrences that are resi stant to medical therapy. However, postpericardiectomy recurrences may occur, possibly due to incomplete resection of the pericardium. This page intentionally left blank 468 CHAPTER 9 Pericardial diseases Tuberculous pericarditis Tuberculous pericarditis is uncommon in the \201 rst world, but is very common in developing countries, and the incidence appears to be increasing in sub-S aharan Africa in parallel with the HIV/AIDS (acquired immune de \201 - ciency syndrome) ep idemic. The disease presents in three forms: pericardial effusion, constrictive pericarditi s, and effusive-constrictive pericarditis. Tuberculous pericardial effusion Pathology: Pericardial effusion is the commonest mode of p resentation, with or without tamponade. The effusion is bloodstained in over 95 % of cases, and may even resemble venous blood. The absence of parenchymal lung disease and the presen ce of hilar lymphadenopathy in many of these patients suggest a direct spread from a TB hil ar node to the pericardium. Clinical presentation: Systemic symptoms are variable. Typical pericardial pain is uncommon and the classic ECG features of pericarditis are uncommon. CXR shows an enlarged globular heart, small pleural effusions on one or both sides, and evidence of pulmonary TB in about 30 % of cases. The echocardiogram shows features of pericardial effusion, typically associa ted with soft tissue density masses, thickening of the visceral pericardium, and \201 bri nous strands. Diagnosis: A de \201 nite diagnosis of TB pericarditis is based on the demonstration of tu bercle bacilli in the pericardial \202 uid or on histologic section of the pericardium. P ericardial effusion should be investigated by pericardiocentesis. Fluid should be sent for microscopy (to identify acid- fast bacilli (AFB)) and culture of Mycobacterium tuberculosis . The chances of a positive culture are improved by bedside inoculation of the \202 uid into double-strength Kirschner culture medium. Pericardial biopsy and drainage offer the ad vantage of a histological diagnosis and early complete drainage of the pericardium. This ca n be performed via the sub-xiphisternal approach under local anesthesia. A probable diagnosis is made when there is proof of TB elsewhere in a patient with unexplai ned pericarditis. Palpation in the supraclavicular fossa will frequently reveal enlarged ly mph nodes, which should be biopsied. AFB-positive sputum will only be found in about 10 % o f cases. Tuberculin skin testing is of little value in endemic and non-endemic areas. It is not known whether the enzyme-linked immunospot (ELISPOT) test that detects T cells speci \201 c for M. tuberculosis antigen will perform better in TB pericarditis than the tubercul in skin test. Several tests have been developed for the rapid diagnosis of TB in the pericardial \202 u id. Polymerase chain reaction (PCR) can identify DNA of M. tuberculosis rapidly from only 1 L of pericardial \202 uid (sensitivity 75 % , speci \201 city 100 % ). An adenosine d eaminase (ADA) level > 40 U/L has a sensitivity of 83 % and a speci \201 city of 78 % . A high interferon G level is also a highly sensitive (92 % ) and speci \201 c (100 % ) marke r of pericardial TB. Treatment: Is by means of standard four-drug anti-TB chemotherapy for 6 months. Overall mor tality ranges from 17 % to 40 % , with HIV-infected individuals having a worse outcome than HIV-negative patients. Repeat pericardiocentesis is required in about 15 % of patients, an d during a two- year follow-up period, about 10 % of patients will require pericardiectomy. URAEMIC PERICARDITIS 469 While some favor the addition of steroids to conventional therapy, their role in improving survival is not clearly established, particularly in HIV infection. Tuberculous pericardial constriction Clinical presentation: Most cases have an active in \202 ammatory \201 brocaseous tissue surrounding the heart, and involving visceral and pa rietal pericardium. The clinical presentation is highly variable. Patients range from being asymptomatic to severe signs and symptoms of constriction. The diagnosis is often missed o n cursory clinical and echocardiographic examination. It is uncommon to \201 nd concomita nt pulmonary TB, and pericardial calci \201 cation is found in <5 % of cases. Treatment: The initial management of patients with non-calci \201 c TB constrictive perica rditis is with anti-TB therapy, and since the process is an active \201 brocaseous condit ion, resolution of constriction occurs in 15 \200\22320 % of patients with medical manageme nt over 3 \200\2234 months. Pericardiectomy is recommended if no improvement has occurred a fter 6 weeks of anti- TB treatment, or improvement is unsatisfactory after several months o f treatment. By contrast, calci \201 c TB pericarditis is treated by early pericardiectomy and anti-TB chemotherapy. Effusive-constrictive tuberculous pericarditis Features: This mixed form is a common presen tation of TB pericarditis. There is increased pericardial pressure due to effusion in the p resence of visceral constriction. The echocardiogram shows porridge-like exudation, with lo culation of the \202 uid. Treatment: Is by standard four-drug therapy. The role of adjuvant steroids is not known. Th e mortality is about 10 % , and about 30 % of cases will come to pericardiectomy over two y ears of follow-up. Uraemic pericarditis Pathology: Uraemia produces a \201 brinous, often haemorrhagic in \202 ammation that may lead to tamponade, and constriction in some cases. Management: Symptomatic pericarditis that occurs before the initiation of dialysis will res pond to repeated peritoneal dialysis or haemodialysis. Heparin-free haemodialysis should be used to avoid haemopericardium. Many patients who develop pericardial effusion while on di alysis (dialysis- associated pericarditis) will respond to intensi \201 cation of the dial ysis regime. Those who do not respond will require drainage by either subxyphoid pericardio tomy or pericardial window. Pericardiocentesis is associated with a high risk of intraperic ardial hemorrhage. 470 CHAPTER 9 Pericardial diseases Neoplastic pericardial disease Etiology: Usually secondary to malignancy of the bronchus, b reast, or kidney. Primary tumors of the pericardium are rare and usually a result of mesoth elioma following asbestos exposure. Diagnosis: Metastases may produce a large haemorrhagic effusion or severe constriction when tumor encases the heart. Malignant cells may be found in 85 % of cases of aspirated perica rdial \202 uid. Tumor markers such as carcinoembryonic antigen (CEA), alpha-feto protein (AFP), and carbohydrate antigens (e.g., CA125) have been used in the diagnosis of malignant effusion. The differentiation of TB and neoplastic effusion is virtually absolute, with lo w adenosine deminase (ADA) and high CEA levels in the latter. Management: Depends on the type and stage of malignancy, condition of the patient, and pres ence of cardiac compression. Pericardiocentesis is effective in relieving neoplastic cardia c tamponade in the vast majority of cases. Commonly, neoplastic pericardial disease is a pr eterminal event. Palliation for recurrent tamponade can be obtained by subxyphoid surgical pericardiotomy (which can be performed under local anesthesia), or by percutaneous balloon pericardiotomy to create a pleuro-pericardial window to allow \202 uid drainage into the pleural space in large malignant pericardial effusions in patients with a limited life expe ctancy. Partial pericardiectomy (pericardial window) through a left thoracotomy should be r eserved for patients who have a better prognosis and are likely to respond to chemotherapy or radiation. Intrapericardial instillation of cytostatic/sclerosing agents has also been used to prevent recurrences of large pericardial effusion. Intrapericardial treatment related to the type of tumor indicates that cisplatin may be effective in secondary lung cancer, and thiotepa m ay be effective in metastatic breast cancer. Tetracycline as a sclerosing agent controls ma lignant pericardial effusion in up to 85 % of cases, but side-effects such as fever, chest pain, atrial arrhythmias, and constriction in long-term survivors are common. Myxoedematous effusion Clinical presentation: Effusion with high protein content is common in untreated myxoedema. Myxoedema must always be excluded in a patient with chronic, asympt omatic, pericardial effusion, associated with bradycardia, low voltage of the QRS complexes , and a history of radiation- induced thyroid dysfunction. Cardiac tamponade does not occur . The diagnosis: Of hypothyroidism is based on serum levels of thyroxine and thyroid-stimulat ing hormone. Treatment: With thyroid hormone causes resolution of the pericardial effusion. RADIATION PERICARDITIS 471 Non-tuberculous bacterial (purulent) pericarditis Predisposing conditions: Immunosuppressio n (e.g. immunosuppressive drugs, lymphoma, or HIV/AIDS); pre-existing pericardial effusion; cardiac surgery; and chest trauma. Children \200\224 pharyngitis, pneumonia, otitis media , endocarditis, and arthritis. Precipitating factors: Cardiac surgery, pericardial aspiration, extension of aortic root en docarditis into the pericardial sac, or haematogenous spread from a septic focus such as os teomyelitis or pneumonia. Causative organisms: Streptococcus pneumoniae, Gram-negative bacilli, and anaerobes. Childr en \200\224 Haemophilus , Staphylococcus aureus , and Neisseria meningitides . Adults \200\224 Staphylococcus aureus , Clinical presentation: Rare in adults without HIV infection. Presents as an acute, fulminat ing infectious illness and is fatal if not treated. The most important reason for this poor outlook is failure to suspect the condition in debilitated patients with overwhelming syst emic infection. Diagnosis: Pericardiocentesis shows purulent \202 uid, with high white cell count, low gl ucose, positive Gram stain for organism, and positive pericardial \202 uid and blood cult ure. Treatment: through a Complete pericardial drainage, preferably subxyphoid pericardiotomy, a nd systemic antibiotic therapy. The mortality rate is 40 % even with appropriate management . Radiation pericarditis This usually follows treatment for lymphoma and breast cancer. The i nci- dence of pericarditis depends on how much the heart is included in the \201 eld of r adiation, the dose, the duration of treatment, and the age of the patient. Radiation is a c ommon cause of effusive-constrictive pericarditis and may also result in myocarditis and pr emature coronary atherosclerosis. Clinical evidence of pericarditis may occur during, or shortly after treatment, but is more usually delayed for approximately 1 year. The presentation is one of pericarditis with som e effusion. In about 50 % of cases there is evidence of tamponade, which requires drainage. Up to 20 % of patients will require pericardiectomy because of severe constriction. The op erative mortality is high (21 % ) and the postoperative 5-year survival is very low (1 % ), mostly due to underlying myocardial \201 brosis and severe thickening of the visceral pe ricardium. 472 CHAPTER 9 Pericardial diseases Drugs and toxins Etiology: Pericardial reactions to drugs and toxins are rare. Pericarditis may develop as part of the lupus erythematosus-like syndrome (hydralazine, isoniazid, proc ainamide, methyldopa, reserpine), hypersensitivity reaction (sodium cromoglicate, penicilli ns, streptomycin), serum sickness, or envenomation (scorpion \201 sh sting). Management: Consists of removal of the causative agent and symptomatic treatment. Postcardiotomy syndrome Clinical presentation: The syndrome occurs in approximately 30 % of patients undergoing any form of cardiac surgery. It is more common in patients receiving a minocaproic acid during the operation. After a latent period of 2 \200\2233 weeks, there is fever, pericarditis, pleuritis, and pneumonitis, with a marked tendency to relapse. Dry pe ricarditis or pericarditis with effusion may occur. The illness is self-limited and varies in intensity and duration, but usually lasts only 2 \200\2234 weeks. Treatment: NSAIDs, analgesics such as aspirin or colchicine. Steroids (oral or intrapericar dial) induce prompt relief of symptoms, but should be reserved for severely affected patien ts, since relapse may occur when they are discontinued and dependency may result. Anticoagu lants should be avoided because of the risk of haemopericardium. Post-infarction pericarditis Clinical presentation: Two forms of post-infarction pericardit is may be distinguished: (1) the usual early form of pericarditis occurs within a week in a t least 20 % of patients with transmural MI. It is a result of pericardial irritation by ad jacent infracted myocardium; (2) less commonly, a delayed autoimmune reaction may produce p ericarditis 2 weeks to a few months after the infarct (Dressler syndrome). The delayed form behaves very similarly to the postcardiotomy syndrome. Treatment: Ibuprofen is said to increase coronary \202 ow, and is the NSAID of choice. As pirin, up to 650 mg every 4 hours for 2 \200\2235 days, has also been used successfully. Oc casionally, steroids may be required for relapse, but should be avoided as they may delay m yocardial healing. Anticoagulants should be avoided because of the risk of haemopericardium . TRAUMATIC PERICARDITIS 473 Rheumatic fever This is an important cause of pericarditis, almost invariably associated wi th severe pancarditis and valvular involvement. Rheumatic pericardial effu- sion is usually clear, straw-colored, and sterile. Cardiac tamponade is rare and the \202 uid usually re sorbs rapidly in response to salicylates or steroid therapy. Chronic constrictive pericardi tis is never rheumatic in origin, but adherent pericardium with \202 ecks of calci \201 cation is not uncommon. Autoimmune pericarditis Pericarditis may be the presenting feature of systemic lupus erythe ma- tosus, or complicate scleroderma and polyarteritis nodosa. Dry or effusive pericarditis may occur, and it is important to exclude these disorders in patients presenting with idio pathic benign pericarditis. Generally, other signs and symptoms of these collagen vascular diseases will be present. Granulomatous pericarditis is a complication of rheumatoid arthritis and ankylosing spondyl itis, leading to effusion and, occasionally, constriction. Aortitis and aortic insuf \201 ciency may be associated, and occasionally there is invasion of the interventricular septum , producing heart block. Traumatic pericarditis This produces two forms of pericarditis. One is a direct result of t rauma with hemorrhage into the pericardial cavity and formation of haemoperi- cardium. If a ssociated myocardial or valvular injury is absent, complete recovery is the rule, although chronic constriction may develop. The second type is a form of recurrent pericarditis allied to the postcardiotomy and post-M I syndromes, which may also result in chronic constriction. 474 CHAPTER 9 Pericardial diseases Fungal pericarditis Clinical presentation: Fungal pericarditis occurs as a rare opportunist ic infection in immunocompromised patients (e.g. immunosuppressive therapy, HIV/AIDS). It i s caused by endemic fungi ( Histoplasma , Coccidioides ), non-endemic opportunistic fungi ( Candida , Aspergillus , Blastomyces ) and semifungi ( Norcadia , Actinomyces ). Diagnosis: Fungal pericarditis may resemble TB pericarditis. Fungal staining and culture of aspirated pericardial \202 uid and pericardial biopsy are necessary to make the distinct ion. Treatment: treatment with \202 uconazole, ketoconazole, itraconazole, amphotericin B or a mphotericin B lipid complex is indicated. NSAIDs are used for symptomatic relief. Sulphonam ides are the drug of choice for norcardiosis, and a combination of three antibiotics includ ing penicillin should be given for actinomycosis. Antifungal Amoebic pericarditis Pathology: Amoebiasis (caused by Entamoeba histolytica ) occurs mainly in endemic areas and in travelers from these areas (in whom the syndrome may appear years later). Pericardial complications are rare but when they occur, they carry a high mortality , especially with delayed or missed diagnosis. The usual cause of amoebic pericarditis is e xtension from an amoebic abscess in the left lobe of the liver. Rarely, spread may also occ ur from the right lobe, or disease may reach the pericardium from an amoebic lung abscess. Clinical presentation: There are two modes of presentation: (1) hepatic presentation \200 \224 an abscess in the proximity of the pericardium, which has not yet ruptured, can cause a pericardial friction rub, a non-purulent pericardial effusion, and ECG and CXR signs of p ericarditis; (2) cardiac presentation \200\224 perforation of the liver abscess into the p ericardium results in a purulent pericarditis. The onset can be acute, with shock and death within a short time, or the onset may be gradual with signs of tamponade as a result of th e pericardial \202 uid. Diagnosis: Is dif \201 cult but should be suspected if, in a patient with a purulent peric arditis and signs of cardiac failure, tenderness of the liver in the epigastrium is much mo re marked than in the rest of the palpable liver. A high and immobile left hemidiaphragm de tected by \202 uoroscopy or CT scan is also suggestive. De \201 nite diagnosis is by per icardiocentesis (which typically shows brownish \202 uid; the pus may simulate anchovy sa uce) and serological testing for antibodies resulting from invasive amoebiasis ( \202 uore scent antibody test, amoebic enzyme immunoassay, or amoebic gel diffusion test). Treatment: Hepatic presentation \200\224 the pericardial disease resolves with successful treatment of the liver abscess. Cardiac presentation \200\224 pericardial drainage and met ronidazole. Constrictive pericarditis is an occasional complication. PERICARDITIS VS. RESTRICTIVE MYOCARDIAL DISEASE 475 Constrictive pericarditis vs. restrictive myocardial disease It is dif \201 cult to separa te congestive pericarditis from restrictive myocardial disease. The distinction is vital be cause pericardiectomy is one of the most satisfying operations in terms of cure. Points of differentiation are listed next. \200 Clinical: murmurs of mitral and tricuspid regurgita tion are strong pointers against constrictive pericarditis. ECG: left axis deviation favors myocardial damage. \200 CXR: pericardial calci \201 cati on favors constrictive pericarditis. \200 ECHO: concentric left ventricular hypertrophy w ith a \200\230sparkling granular \200\231 appearance in amyloid. Left ventricular hypertrophy may be present in hae mochromatosis. Endomyocardial \201 brosis is characterized by obliteration of the left ve ntricular wall. The ejection fraction is normal in constrictive pericarditis, whereas in he art muscle disease, left ventricular function is frequently depressed. On tissue Doppler im aging, a peak early velocity of longitudinal expansion (peak E a ) of (cid:116) 8.0 cm/s di fferentiates patients with constriction from those with restriction, with 89 % sensitivity and 100 % speci \201 city. CT and MRI scan: these are diagnostic when they show thickened pericardium (cid:116) 5 mm. Cardiac catheterization: when the right ventricular and left ventricular end-diastolic pres sures differ by more than 6 mmHg, restrictive cardiomyopathy is probably present. A pulmona ry artery pressure of more than 50 mmHg strongly favors restrictive cardiomyopathy. \200 Endomyocardial biopsy: is diagnostic of in \201 ltration in amyloid disease and haemochrom atosis. Extensive \201 brosis is indicative of restrictive cardiomyopathy. An exploratory thoracotomy is justi \201 ed if all these tests fail to make a distinction between the two entities. 476 CHAPTER 9 Pericardial diseases Pericardial \202 uid analysis Analyzes of pericardial effusion can establish the diagnosi s of viral, bacterial, tuberculous, fungal, amoebic, and malignant pericarditis. The appear ance of the pericardial \202 uid should be noted. The tests should be ordered according t o the clinical presentation of the patient. However, the following routine samples are usef ul: (1) biochemistry sample for protein and lactate dehy- drogenase (LDH) estimation to dis tinguish between an exudate and a tran- sudate; (2) microbiology specimen for microscopy, c ulture, and sensitivity testing; (3) cytology specimen. The following tests are requested f or diag- nosis of the speci \201 c forms of pericarditis: \200 viral pericarditis \200 \224 PCR for cardiotropic viruses \200 purulent pericarditis \200\224 Gram stain, at lea st 3 cultures of pericardial \202 uid for aerobes and anaerobes and blood cultures TB pericarditis \200\224 staining for AFB; bedside inoculation of pericardial \202 uid into double-strength Kirschner transportation medium and culture; ADA level fungal pericarditis \200\224 microscopy and culture \200 amoebic pericarditis \200\224 brownish pericardial \202 uid with anchovy sauce appearance of pus malignant effusion \200\224 cytology and tumor markers (e.g. CEA). Further reading Chesler E ( 1992 ). Clinical cardiology . 5th ed. New York : Springer-Verla g . Commerford PJ , Strang JIG . Tuberculous pericarditis . In: Coovadia HM , Benatar SR (e ds) ( 1991 ). A Century of Tuberculosis: South African perspectives . Cape Town : Oxford Un iversity Press , pp 123 \200\223 36 . Maisch B, Seferovic PM, Ristic AD, et al . ( 2004 ). Guidelines on the diagnosis and ma nagement of pericardial diseases executive summary; The Task force on the diagnosis and man agement of pericardial diseases of the European society of cardiology. Eur Heart J 25 : 587 \200\223 610. Syed FF , Mayosi BM . Pericardial disease: an evidence based approach to diagnosis and trea tment . In: Yusuf S , Cairns JA , Camm AJ , et al . (eds) ( 2009 ). Evidence based cardiolo gy , 3rd edition. London : BMJ Books . 477 Chapter 10 Arrhythmias The cardiac conduction system 478 Bradycardia: general approach 480 Sinus bradycardia 482 S inus pause 482 Sick sinus syndrome 482 Atrioventricular block 483 Bundle branch block 484 T achycardia: general approach 486 Tachycardia: emergency management 488 Tachyarrhythmias: cl assi \201 cation 490 ECG diagnosis of tachyarrhythmias 492 Supraventricular tachycardia 49 4 Sinus tachycardia 494 Sinus nodal re-entrant tachycardia 495 Atrial tachycardia 496 Atrio ventricular nodal re-entrant tachycardia (AVNRT) 498 Atrioventricular re-entrant tachycardi a (AVRT) 498 Junctional tachycardia 498 Atrial \201 brillation 500 Atrial \201 brillati on: investigations 502 Atrial \201 brillation: management 504 Ventricular tachycardia 508 Normal heart VT (benign VT) 508 VT with impaired LV function 510 Palpitations: general app roach 512 Syncope: general approach 514 Syncope: management 517 Inherited arrhythmia syndro mes 518 Long QT syndrome 518 Long QT syndrome, continued 520 Long QT syndrome: management 5 22 Arrhythmogenic right ventricular cardiomyopathy (ARVC) 524 Brugada syndrome 526 Catechol aminergic polymorphic VT 526 Arrhythmia in special situations 528 Permanent pacemakers 530 Which pacing modality? 533 Complications of pacing 534 Pacemaker follow-up 536 Cardiac resy nchronization therapy 538 478 CHAPTER 10 Arrhythmias The cardiac conduction system Cardiac action potential The resting cardiac myocyte is elect rically negative, with a transmembrane voltage of between \210\222 50 mV and \210\222 95 mV. This is due to the distribution of K + , Na + , Cl \200\223 , and Ca 2 + ions across t he cell membrane. The negativity is maintained by the energy-consuming Na + /K + pump, whic h transports three Na + ions out of the cell for two K + ions inward. During phase 4 of the action potential, the voltage slowly increases until a threshold of \210\222 60 mV is rea ched, which opens voltage-gated Na + channels and triggers depolarization. The voltage chan ges in one cell are spread to adjacent cells via gap junctions between them, such that a wa vefront of electrical activa- tion is propagated. At least ten distinct ion channels modula te the voltage changes that occur in the action potential (Figs. 10.1 and 10.2). Automatici ty This is the ability of all cardiac cells to spontaneously depolarize. It is caused by th e inward \202 ow of positive ions during diastole. At potentials more negative than \210 \222 60 mV, ion channels open allowing a slow in \202 ux of cations. The slow in \202 ux of Ca 2 + in the sinoatrial node (SAN) allows it to depolarize more rapidly and therefore s uppress other potential pacemaker sites. Sinoatrial node The SAN sits high in the lateral right atrium (RA) just below the superior vena cava (SVC). It is 1 \200\2232 cm in length, 2 \200\2233 mm wide, and less than 1 mm fr om the epicardial surface. It is the dominant site of impulse generation; impulses are cond ucted out of the sinus node to depolarize the surrounding RA. The SAN is richly innervated with both adrenergic and cholinergic receptors, which alter the rate of depolarization henc e controlling the heart rate. Activation spreads out from the SAN to the rest of the RA and left atrium (LA) via specialized interatrial connections including Bachmann \200\231s bund le. Atrioventricular node The atrioventricular node (AVN) is found in the RA anterior to the mo uth of the coronary sinus and directly above the insertion of the septal lea \202 et of th e tricuspid valve. It is the only electrical connection to the ventricle, via the bundle of His, which, like the SAN it is also densely innervated with sympathetic and parasympatheti c \201 bres. His \200\223Purkinje system The electrical impulse conducts rapidly through the bundle of H is into the upper part of the interventricular septum, where it splits into two branches: t he right bundle branch, which continues down the right side of the septum to the apex of th e right ventricle and the base of the anterior papillary muscle, and the left bundle branch , which further splits into two fascicles, anterior and posterior. The terminal Purkinje \201 bres connect with the ends of the bundle branches, forming an interweaving network on the endocardial surface so that a cardiac impulse is transmitted almost simultaneously to t he entire right and left ventricles. THE CARDIAC CONDUCTION SYSTEM 479 1 2 0 3 \200\22360 mV 4 \200\22380 mV Fig. 10.1 The cardiac action potential . The action potential has \201 ve parts: 0 rapid in \202 ux of Na + causing fast depolarization 1 rapid early repolarization due to ef \202 ux of Na + 2 plateau phase where repolarization is slowed by an in \202 ux of Ca 2 + 3 repolarization due to the the ef \202 ux of K + 4 diastole with a steady-state resting t ransmembrane voltage. The plateau phase distinguishes the cardiac from neuronal action pote ntial. The release of Ca 2 + during phase 2 triggers mechanical contraction of the cell. SAN AVN MV His bundle TV Left bundle branch Right bundle branch Left anterior and posterior hemi fasicles Fig. 10.2 Anatomy of the normal conduction system. AVN = atrioventricular node; MV = mitral valve;. SAN = sinoatrial node; TV = tricuspid valve. 480 CHAPTER 10 Arrhythmias Bradycardia: general approach \200 Ask speci \201 cally about previous cardiac disease, palpitations, blackouts, dizziness, chest pain, symptoms of heart failure, current medicati on. Examine carefully, noting the blood pressure (BP), jugular venous pressure (JVP) waveform (?cannon waves), heart sounds and murmurs, and signs of heart failu re. Investigations 12-lead electrocardiogram (ECG) and rhythm strip Look speci \201 cally for the relationship between P waves and QRS complex. A long rhythm strip is sometimes necessary to detect complete heart block if atrial and ventricular rates are similar Blood tests Full blood count (FBC), biochemistry, glucose (urgently) Ca 2 + , Mg2 + (especially if on d iuretics) Biochemical markers of cardiac injury Where appropriate Blood cultures, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) Thyroid func tion tests (TFTs) Drug levels. Arterial blood gasses Chest x-ray Heart size ?Signs of pulmonary oedema Emergency nanagement Haemodynamically unstable patients \200 Severe haemodynamic compromi se (cardiac arrest, asystole, systolic blood pressure (SBP)<90 mmHg, severe pulmonary oedema, evidence of cerebral hypoperfusion) needs immediate treatment. \200 Give oxygen via face mask if the patient is hypoxic on ai r. \200 Keep nil by mouth (NBM) until de \201 nitive therapy has been started, to reduce the risk of aspiration in case of cardiac arrest or when the patient lies supine for temporary wire insertion. Secure peripheral venous access. \200 Give atropine 1 mg IV (MiniJet ) bolus; repeat i f necessary up to a maximum 3 mg. Give isoprenaline 0.2 mg IV (MiniJet ) if there is a delay in pacing and the patient rem ains unstable. Set up an infusion (1 mg in 100 mL 1 M saline starting at 1 mL/min titrating to heart rate (HR)). Insert temporary pacing wire (technique described in b Temporary ventricular pacing, p. 808 ). If this is not possible immediately, set up an external pacing system and transfer to a screening room for trans- venous pacing. Look for and treat reversible causes ; drug overdose ( B -blockers, verapamil, diltiazem, digoxin), hypothyroidism, hypothermia, myocardial infarction (MI), in fective endocarditis). BRADYCARDIA: GENERAL APPROACH 481 Haemodynamically stable patients \200 Admit to the coronary care unit (CCU) with continuo us ECG monitoring. Keep atropine drawn up and ready in case of acute deterioration. \200 Avoid temporary pac ing wire unless there is haemodynamic deterioration. Long-term management \200 Ensure all possible underlying causes have been identi \201 ed and removed. \200 Regardless of etiology if symptomatic bradycardia remains refer for permanent pacing (see b p. 530). Complete heart block should always be referred for a permanent pacemaker, whether symptomatic or not. External cardiac pacing \200 In emergencies, external cardiac pacing (via an external de \201 brillator that can pace) may be used \201 rst, but this is only a temporary measure until a more \200\230de \201 nitive \200\231 transvenous pacing wire can be inserted. The de \201 brillator ECG electrodes need to be attached. \200 Attach the de \201 brill ation patches to the anterior and posterior chest wall. Turn the output up (in volts or amp eres) until ventricular capture with QRS complexes is seen. This will also cause extremely unpleasant thoracic muscular capture, so the patient must be sedated with benzodiazepam External cardiac pacing is useful as a standby in patients, e.g. post-MI, when the risks of prophylactic transvenous pacing after thrombolysis are high. Haemodynamically stable patients with anterior MI and bifasicular block may be managed simp ly by application of the external pacing electrodes and having the pulse generator ready if necessary. Familiarize yourself with the machine in your hospital when you have some time \200\224 a cardiac arrest is not the time to read the manual for the apparatus! 482 CHAPTER 10 Arrhythmias Sinus bradycardia In sinus bradycardia, the SAN discharges <60/min. P waves are normal but slow. It may be normal (e.g. in sleep, healthy resting hearts). Causes \200 Young athletic individual \200 Healthy resting heart, e.g. sleep \200 Chr onic degeneration of sinus or AV nodes or atria \200 Drugs \200\224 B -blockers, morphin e, amiodarone, calcium-channel blockers, lithium, propafenone, clonidine Increased vagal tone \200 vasovagal attack \200 nausea or vomiting \200 carotid sinus hypersensitivity Hypothyroidism \200 Hypothermia \200 MI or ischaemia of the sinus node \200 Cholestat ic jaundice \200 Raised intracranial pressure