Synthetic ECG-gated cardiac computed tomography for in vivo imaging of the temporary total artificial heart.

To date, there have been >1000 implantations of temporary total artificial hearts (TAH-t). As expected, complications related to the use of the TAH-t can occur. A noninvasive imaging modality that would be capable of diagnosing mechanical failure, surgical complications, and thromboembolic phenomena related to the TAH-t is desirable. Echocardiography is not suitable to evaluate a TAH-t because ultrasound cannot penetrate air and the polyurethane components in the TAH-t assembly. Cardiac magnetic resonance imaging is likewise unsuitable because of the susceptibility to artifacts that the titanium valve components in the TAH-t would create. Conventional computed tomography (CT) is limited by motion artifact. Cardiac CT (CCT) can produce motion-artifact–free images of the heart. If performed with retrospective gating, CCT can also be used to acquire time-resolved images. However, CCT requires simultaneous recording of the patient’s ECG, and patients who have a TAH-t do not generate an ECG. Consequently, a variation in technique is necessary to image patients with TAH-t with this modality. Detailed below is a simple method of CCT for the TAH-t that uses a patient simulator device to generate a synthetic ECG signal. A patient simulator device is a readily available instrument normally used to test and calibrate ECG machines. A 20-year-old male patient presented with severe pain in his left torso 74 days after implantation of a TAH-t (SynCardia TAH-t, SynCardia Systems Inc, Tucson, AZ). At the time of presentation, the patient weighed 90 kg and had a body surface area of 2.13 m. His creatinine and glomerular filtration rate were normal (0.87 mg/dL and >60 mL/min, respectively). The patient’s surgeon requested a CCT of the thorax followed by a helical CT scan of the abdomen to help determine the cause of the pain. A dual-source, 32–detector-row, Z-flying focal spot CT scanner (SOMATOM Definition, Siemens Healthcare, Forchheim, Germany) was used to perform the scan. The