Overview.
Radiation pericarditis is caused by radiation injury to the myocardium and pericardium, and is often a complication of radiation therapy for thoracic and mediastinal malignancies. A few present with acute pericarditis symptoms, fever, precordial pain, anorexia, and general malaise. Delayed pericarditis often presents with acute nonspecific pericarditis or asymptomatic pericardial effusion and pleural effusion from 4 months to 20 years after radiation therapy, most commonly within 12 months. Pericardiocentesis or pericardiectomy is required if necessary.
Etiology
Radiation pericarditis is a serious complication of radiation therapy for breast cancer, Hodgkin’s disease, and non-Hodgkin’s lymphoma. Damage to the myocardium and pericardium from radiation therapy depends on (i) the dose of radiation therapy; (ii) the number of treatments and the duration of the treatments; (iii) the volume of the heart included in the area irradiated by radiation therapy; and (iv) the uneven distribution of the 60 cobalt (60Co) irradiation compared with that of linear gas pedals.
Symptoms
A few manifest acute pericarditis symptoms, fever, precordial pain, anorexia, general malaise, pericardial friction sounds and ECG abnormalities. Delayed pericarditis often occurs 4 months to 20 years after radiation therapy, most commonly within 12 months, with acute nonspecific pericarditis or asymptomatic pericardial effusion and pleural effusion, which gradually subside over months or years. About 50% of patients present with chronic massive pericardial effusion with varying degrees of cardiac tamponade, and the clinical manifestations of pericardial constriction may be seen in patients with a long course of the disease.
Examination
1. Electrocardiography
Most patients have low voltage. About 70% of patients have P-wave abnormality, P-wave widening or P-wave tangential, or both, and T-wave flattening or inversion. 1/3 to 2/3 of patients have atrial arrhythmia, and most of the atrial arrhythmia is atrial fibrillation.
2. Echocardiography
The pericardium is obviously thickened or adherent, with enhanced echogenicity; the left ventricular free wall is flat and straight in mid-late diastolic motion; the mitral valve closes quickly in the early stage; the pulmonary valve opens prematurely; the ventricular septum is abnormal and the ventricular end-diastolic diameter is narrowed. The inferior vena cava is abnormally dilated.
3. X-ray examination
The heart shadow is normal or slightly large or small. The cardiac silhouette is irregular and rigid. Widening of the superior mediastinum is caused by enlargement of the superior vena cava, and the surrounding lung field is clear. 50% to 90% of patients can see pleural effusion, and unilateral pleural effusion without mediastinal displacement is an important sign of constrictive pericarditis. Calcification of the pericardium is also the main evidence of X-ray changes, and it is characterized by extensive calcification sites, which coexist with clinical features to make the diagnosis clear. About 70% of patients have signs of calcification.
4. CT and MRI
CT and MRI can clearly show the degree of pericardial thickening, with a positive rate of about 80%. High-speed CT (UFCT) is more accurate. Magnetic resonance is the best non-invasive test for the diagnosis of constrictive pericarditis. It can accurately measure the pericardial thickness as well as the degree of right atrial dilatation and right ventricular narrowing.
5. Cardiac catheterization
Equal end-diastolic pressures in the right atrium, pulmonary artery and left atrium are the hallmarks of the disease. Right ventricular pressure decreases rapidly in early diastole, then rises rapidly, followed by a flat line in mid- and late diastole, called the “square root sign”, which also supports the diagnosis of the disease.
6. Laboratory tests
Some patients may present with severe hypoproteinemia and anemia. Individuals may have abnormal liver function and jaundice.
Diagnosis
Clinical diagnosis can be established when pericarditis or pericardial effusion occurs in the presence of a malignant tumor and radiation therapy.
Treatment
Asymptomatic pericardial effusion after radiation therapy with regular follow-up does not require special treatment. Large pericardial effusions, cardiac tamponade, or histologic examination for definitive diagnosis require pericardiocentesis. Severe intractable pain and life-threatening pericardial effusion can be treated with hormonal therapy. Repeated large pericardial effusions and severe exudative-constrictive pericarditis are treated with pericardiectomy.