Inflammatory Heart Diseases
Objectives - Differentiate endocarditis, myocarditis, and pericarditis.
Three Inflammatory Heart Diseases
| Disease | Source definition |
|---|---|
| Endocarditis | Inflammation of the inner lining of the heart chambers, or endocardium. |
| Myocarditis | Inflammation of the heart muscle, or myocardium. |
| Pericarditis | Inflammation of the outer lining of the heart, or pericardium. |
Infective Endocarditis
Infective endocarditis is a heterogeneous disease process that includes several disease processes leading to heart dysfunction.
Patients often develop several bacterial infections, described as polybacterial, which can lead to progressive heart dysfunction. Bacterial species produce biofilm that allows attachment to the wall. This can create vegetation and large growths within the heart.
Vegetation may lead to tissue breakdown, valve obstruction, turbulent flow, and higher incidence of thrombosis.
Endocarditis Risk History and Symptoms
Patients with infective endocarditis typically have a history of:
- Previous infective endocarditis
- Chronic intravenous access
- Intravenous drug abuse
- Indwelling endocavitary devices
- Diabetes mellitus type 2
- Underlying malignancy
- Renal failure requiring hemodialysis
- Chronic immunosuppressive therapy
Symptoms are varied, and some patients have no symptoms. Non-specific symptoms such as chills, sweats, cough, and headache can make identification difficult. Chest angina, arm pain, back pain, and abdominal pain may occur. Some patients present with a murmur, especially patients with left-sided infective endocarditis.
Endocarditis Diagnostics and Treatment
Echocardiography is first-line detection for endocarditis. TTE can detect most cases. TEE may provide a better view of the valves and improve detection of specific lesions and vegetation.
Patients may receive TEE or TTE when they have:
- Suspected endocarditis with or without blood cultures to detect valvular vegetations
- Valve lesions
- High-risk features such as virulent organisms, clinical deterioration, or new murmur
- Prosthetic valves
Lab values may be ineffective in detecting infective endocarditis. White blood cell levels often stay the same, though serum creatinine may be elevated. EKG findings are likely nonspecific. The source states most infective endocarditis is identified by cardiac abscesses and blood culturing.
Other criteria include vegetation of a valve or implanted material, abscess, and new or partial dehiscence of a prosthetic valve.
Treatment includes antibiotics based on the specific infection and surgery on the affected implanted device to remove the device or vegetation.
Myocarditis
Myocarditis is any inflammation of the myocardium. It is caused primarily by injury or external antigens such as bacteria, viruses, drugs, or toxins. Autoimmune disease can also lead to myocarditis.
Clinical presentation varies widely, which makes diagnosis and classification difficult. Findings may range from asymptomatic ECG or echocardiographic abnormalities to chest pain, cardiac dysfunction, arrhythmias, heart failure, and hemodynamic collapse.
Myocarditis Types
| Type | Source points |
|---|---|
| Acute myocarditis | Fatigue, dyspnea on exertion, arrhythmias, palpitations, and chest pain. Usually idiopathic but can be viral or traumatic. |
| Fulminant myocarditis | Abrupt onset within days of viral illness, hemodynamic compromise, hypotension, and need for pressors or mechanical support. Echo shows hypofunction and ventricular thickening. |
| Giant cell myocarditis | Giant cells with active inflammation and scar tissue. Early immunosuppressive therapy may prolong life, but transplant or mechanical support remain treatments. |
| Chronic active myocarditis | Borderline myocarditis category with few inflammatory infiltrates and no demonstrated myocyte injury. Usually older populations with ventricular dysfunction, fatigue, and dyspnea. |
| Eosinophilic myocarditis | Usually results from a foreign antigen, typically a drug. Treatment focuses on the underlying condition and removing or treating the offending agent. |
| Peripartum myocarditis | Left ventricular dysfunction in the last month of pregnancy or within 5 months of delivery without preexisting cardiac dysfunction or other cardiomyopathy cause. |
Myocarditis Diagnostics
Diagnosis is difficult because symptoms are broad and non-specific. Histological examination of the heart is often the only definitive method of identifying myocarditis.
Three findings may help:
- Otherwise unexplained rise in troponin concentrations
- ECG changes suggestive of acute myocardial injury
- Heart dysfunction on echocardiogram, TEE, or CMR
Laboratory testing usually shows cardiac injury biomarkers in patients with acute viral illnesses. Elevated troponin is generally noted in most myocarditis types.
Assessment of left ventricular function is essential in suspected myocarditis and is done by cardiac imaging. Echocardiography is an excellent imaging choice, though there are no specific echocardiographic features of myocarditis. Some ventricular dilation with reduced systolic function may be seen.
Acute Pericarditis
Acute pericarditis is symptoms or signs from pericardial inflammation lasting no more than 1 to 2 weeks. It can occur from several diseases but is often idiopathic. The source states most idiopathic cases are presumed viral.
Acute pericarditis accounts for some emergency room patients with nonischemic chest pain. It generally presents with acute chest pain relieved by sitting forward.
Uncomplicated cases may have a rub heard through auscultation during ventricular systole and early diastolic filling. The source recommends having the patient lean forward and listening at the lower left sternal border for a sound like crunchy snow.
EKG may show ST segment elevation, which must be differentiated from myocardial infarction. Treatment includes NSAIDs and corticosteroids.
Pericardial Effusion and Tamponade
Pericardial effusions and tamponade can be caused by:
- Idiopathic pericarditis
- Infection
- Neoplasm
- Autoimmune or inflammatory processes that can cause pericarditis
- Penetrating or blunt trauma
- Cardiac surgery or percutaneous cardiac procedures
Tamponade occurs when pressure within the pericardial sac increases enough to affect the heart's ability to work.
Clinical features include Beck's triad: hypotension, muffled heart sounds, and elevated jugular venous pressure. Patients with effusions are often more comfortable sitting forward. Reduced cardiac output, reduced blood pressure, pericardial pain or nonspecific discomfort, and paradoxical pulse may also occur.
Identification includes echocardiography, ECG, and chest x-ray.
Management depends on whether tamponade is present or may occur in the future. Treatment may include pericardiocentesis with corticosteroids. The most common closed pericardiocentesis approach is subxiphoid needle insertion under echocardiographic guidance.
Constrictive Pericarditis
Constrictive pericarditis is the end stage of an inflammatory process involving the pericardium. In the developed world, causes are most commonly idiopathic, postsurgical, or radiation injury. Tuberculosis was the most common cause before effective drug therapy and remains important in developing countries.
Over time, pericardial disease can produce scarring that impedes the heart's ability to fill its chambers. Some patients may be relieved with anti-inflammatory drugs.
The pathology is marked restriction of heart chamber filling. This causes elevated and equal filling pressures in all chambers and in the systemic and pulmonary veins. It can lead to impaired filling, fatigue, muscle wasting, and weight loss.
Diagnosis may show an enlarged heart on chest x-ray, but ECG may not detect it. M-mode, two-dimensional transthoracic, and Doppler echocardiographic techniques are key imaging modalities.
Effusive-constrictive pericarditis combines elements of effusion or tamponade and constriction. Causes include idiopathic disease, malignancy, radiation, tuberculosis, pericardiotomy, and connective tissue diseases.