A 6-year-old boy with cyanosis shortly after birth was initially suspected of congenital heart disease based on local echocardiography findings, but the precise diagnosis remained elusive. Recently, his cyanosis progressively became worse, and his activity level was severely limited, prompting him to seek medical attention. Cardiac ultrasound examination showed multiple complex abnormalities, including the functional single atrium, complete atrioventricular septal defect, total anomalous pulmonary venous connection (supracardiac type), pulmonary artery atresia, and collateral vessel formation. To further clarify the diagnosis and develop an effective treatment plan, diagnostic cardiac catheterization under general anesthesia was needed. The child’s red blood cells were significantly increased with hematocrit level reaching 70% due to long-term hypoxia. To reduce the risks of thrombosis, embolism, and coagulation dysfunction, acute normovolemic hemodilution with plasma was performed before the cardiac catheterization procedure, which was carried out by blood withdrawal of 20 mL from the femoral artery and simultaneous administration of an equivalent volume of homologous frozen plasma through the femoral vein. When the 180 mL volume of blood was replaced, the end-tidal carbon dioxide waveform was significantly altered with a partial pressure drop from 40 mm Hg to about 23 mm Hg, SpO2 decreased markedly, and the heartbeat gradually slowed, leading to cardiac arrest. Prompt cardiopulmonary resuscitation was initiated, the heartbeat resumed shortly after cardiopulmonary resuscitation, and the vital signs were also back to baseline. In the end, this cardiac catheterization procedure was postponed, and the child was transferred to the intensive care unit with mechanical ventilation for further monitoring.