Heart disease following radiation

Constrictive pericarditis in childhood due to mediastinal irradiation

Between 1955 and 1972, eight children receiving mediastinal irradiation for intrathoracic malignancy developed constrictive pericarditis. Six of these followed irradiation for Hodgkin's disease and represent 7% of 86 children receiving irradiation for that disease. In patients with Hodgkin's disease, the development of constrictive pericarditis was related to the dose of radiation and the use of orthovoltage technique. Constrictive pericarditis has not yet developed among the 44 children radiated by supravoltage technique. Symptoms of constrictive pericarditis occurred an average of 15 months (4/12 to 3 2/12 years) after irradiation and were preceded in five of the eight patients by acute pericarditis. Prominent clinical findings included dyspnea, Kussmaul sign, pulsus paradoxicus, hepatomegaly, cardiomegaly and electrocardiographic evidence of low QRS voltages with ST-T wave changes. Pericardiectomy was performed in six patients and resulted in immediate but only transient symptomatic relief. There was no operative mortality. Death occurred in six of the eight patients (1 5/12 to 6 6/12 years following irradiation) due to cardiac disease in three, progression of the malignancy in two and infection in one. In addition to constrictive pericarditis, extensive myocardial fibrosis and involvement of the antero-lateral papillary muscle and chordae tendineae of the mitral valve were demonstrated at postmortem examination. These factors may explain the progression of cardiac disease despite an initial symptomatic improvement following pericardiectomy.

Myocardial fibrosis in constrictive pericarditis. Electrocardiographic and pathologic observations

It has been suggested that a tentative preoperative decision favoring a pericardial lesion, on the one hand, or a myocardial lesion, on the other, may be made from certain noninvasive procedures, including the electrocardiogram. An attempt was therefore made to detect associated myocardial fibrosis by electrocardiogram in 67 patients with constrictive pericarditis as proven at catheterization (63 patients), surgery (64 patients) or postmortem examination (12 patients). Seven of the 67 had electrocardiograms characteristic of, and 16 compatible with, old myocardial infarct. The electrocardiographic experience was otherwise typical of the literature with non-specific changes in the T waves or RS-T segments and/or low voltage in the remaining 44. All three autopsied patients whose electrocardiograms were interpreted as diagnostic of an old myocardial infarct and both autopsied patients with electrocardiograms compatible with that diagnosis showed myocardial fibrosis. In seven autopsied cases with non-specific T waves or low voltage, the myocardium was normal in three while four showed myocardial fibrosis. It appears that in a few cases right ventricular hypertrophy might have simulated infarct by inducing tall R waves over the right precordium, or R waves which decreased in amplitude as the electrode was passed from the right to the left precordium.

Pathologic evidence related myocardial fibrosis to: (1) direct subepicardial penetration by the inflammatory process or deposit of fat in the subepicardial myocardium; (2) compromise of coronary blood flow, as by (a) direct throttling of coronary arteries by scar tissue or (b) deficient irrigation of subendocardial layers due to rigidity of the pericardium; or (3) a concomitant myocardial and pericardial process (lupus, radiation fibrosis, rheumatoid). Independent pericarditis and coronary disease was surprisingly rare. This limited experience (1) suggests that, though myocardial fibrosis may be predicted in constrictive pericarditis if the electrocardiogram shows characteristic changes of myocardial infarction, non-specific T wave changes or low voltage may likewise be associated with myocardial fibrosis, and (2) emphasizes that the difficulty in determining the site of a constrictive process may be compounded by the co-existence in the same heart of both a pericardial and a myocardial process.

Subacute effusive-constrictive pericarditis

Clinical and hemodynamic observations are reported in 13 patients who demonstrated a distinct pathophysiologic form of compressive pericardial disease characterized by effusion into a free pericardial space associated with constriction of the heart by the visceral pericardium. The pericardial disease was idiopathic (nine patients) or subsequent to radiotherapy (four patients), with a maximal duration of symptoms of 16 months. Enlarged heart shadow, prominent paradoxical pulse, predominant systolic dip in the venous pressure pulse, and absence of atrial fibrillation were features that tended to distinguish the effusive-constrictive cases from those with noneffusive chronic constrictive pericarditis. The value of pressure measurements during combined cardiac catheterization and pericardiocentesis is emphasized in the differentiation of effusive-constrictive pericarditis from cardiac tamponade without constriction. Four patients were observed to progress through an effusive-constrictive phase to noneffusive constrictive pericarditis. Corticosteroids, pericardiocentesis, and other medical therapy produced some benefit but did not relieve constriction. The results of surgery were generally satisfactory.

Irradiation-induced constrictive pericarditis in intestinal lymphangiectasis

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