Fatality Immediately Following Rapid Infusion of Macroaggregates of99mTc Albumin (MAA) for Lung Scan

LUNG SCANNING has recently gained increasing acceptance as a diagnostic aid in pulmonary disease since it supplies information which is in some ways similar to that obtained by pulmonary angiography (1–4) and is performed with less technical difficulty and risk (5, 6). To date only one adverse reaction has been reported (7, 8). The purpose of this report is to record an immediate and fatal reaction following infusion of 99mTc-MAA (technetium-labeled MAA). The possible relationship between our patient's advanced pulmonary vascular disease and the fatal reaction will be discussed. Case Report In this 7-year-old Caucasian male, a thoracolumbar meningomyelocele had been diagnosed at birth and a ventriculojugular shunt procedure performed to alleviate noncommunicatirig hydrocephalus. The shunt functioned well until the child was six and a half years of age when it required revision. At that time a chest film demonstrated normal cardiac size and contour. Fifteen months later, persistent dependent edema developed, together with cough and dyspnea on exercise. Physical examination disclosed a blood pressure of 110/60 mm Hg, a pulse of 110, and a respiratory rate of 32. Neck veins were not distended. Pulmonary valve closure was palpable and markedly accentuated on auscultation at the second left interspace. A very prominent fourth heart sound was heard along the left sternal border. Pitting edema extended to the midthighs. An electrocardiogram showed right atrial ventricular hypertrophy. Chest roentgenograms demonstrated marked interval increase in cardiac size and prominence of the main pulmonary artery (Fig 1). Pulmonary vascularity was normal, and there was no pulmonary fibrosis or infiltrate. Right ventricular pressure at this time was 120 mm Hg. The intravascular portion of the shunt was removed and directed into the peritoneal cavity. During the next five months, the patient had increased symptoms with no benefit from therapy. A second cardiac catheterization showed a right ventricular pressure of 136/20–30 mm Hg. Angiocardiography was performed from the right atrium, using 2/3 cc/kg of 76 per cent methylglucamine diatrizoate. No adverse reaction was observed and right atrial pressure did not change following the injection. Two weeks later, a lung scan was attempted by intravenous injection of a suspension which contained 3.8 mg (0.16 mg/kg) of albumin and 800 microcuries of 99mTc in 3.8 cc volume. Within one minute, the intravenous injection was followed by labored respiration and audible wheezing, and the patient attempted to sit up but became unconscious and apneic. The peripheral pulse was weakly palpable, but the blood pressure was unobtainable. He was immediately intubated, ventilated with oxygen, and given closed chest cardiac massage. Epinephrine and sodium bicarbonate were injected into the heart without benefit.