Assessment of Cardiac Device Position on Supine Chest Radiograph in the ICU: Introduction and Applicability of the Aortic Valve Location Ratio.

Abstract

The use of intracardiac assist devices is expanding, and correct position of these devices is required for optimal functioning. The aortic valve is an important landmark for positioning of those devices. It would be of great value if the device position could be easily monitored on plain supine chest radiograph in the ICU. We introduce a ratio-based tool for determination of the aortic valve location on plain supine chest radiograph images, which can be used to evaluate intracardiac device position. Retrospective observational study. Large academic medical center. Patients admitted to the ICU and supported by an intracardiac assist device. We developed a ratio to determine the aortic valve location on supine chest radiograph images. This ratio is used to assess the position of a cardiac assist device and is compared with echocardiographic findings. Supine anterior-posterior chest radiographs of patients with an aortic valve prosthesis (n = 473) were analyzed to determine the location of the aortic valve. We calculated several ratios with the potential to determine the position of the aortic valve. The aortic valve location ratio, defined as the distance between the carina and the aortic valve, divided by the thoracic width, was found to be the best performing ratio. The aortic valve location ratio determines the location of the aortic valve caudal to the carina, at a distance of 0.25 ± 0.05 times the thoracic width for male patients and 0.28 ± 0.05 times the thoracic width for female patients. The aortic valve location ratio was validated using CT images of patients with angina pectoris without known valvular disease (n = 95). There was a good correlation between cardiac device position (Impella) assessed with the aortic valve location ratio and with echocardiography (n = 53). The aortic valve location ratio enables accurate and reproducible localization of the aortic valve on supine chest radiograph. This tool is easily applicable and can be used for assessment of cardiac device position in patients on the ICU.