An apparatus for determining an angulation of a C-arm image acquisition system for a cardiac intervention, comprising: means for receiving a 3D ultrasound image including a cardiac region using an ultrasound probe at the beginning of the cardiac procedure or directly from the ultrasound probe in real time during the cardiac procedure, wherein the 3D ultrasound image comprises a transesophageal echo, TEE, or intracardiac echo, ICE; means for registering the 3D ultrasound image to a 3D coordinate system of the C-arm image acquisition system; means for detecting a cardiac structure of interest in the registered 3D ultrasound image; and means for automatically determining an angulation of the C-arm image acquisition system based on the detected structure of interest in the registered 3D ultrasound image; wherein the means for registering the 3D ultrasound image to a 3D coordinate system of the C-arm image acquisition system comprises: means for detecting a position of an ultrasound probe in a 2D x-ray image acquired by the C-arm image acquisition device ; means for estimating a pose of the ultrasound probe in the 3D coordinate system of the C-arm image acquisition device based on the detected position of the ultrasound probe in the 2D x-ray image using a probabilistic boosting tree; and means for registering the 3D ultrasound image to the 3D coordinate system of the C-arm image acquisition device based on the estimated pose of the ultrasound probe in the 3D coordinate system of the C-arm image acquisition device . means for receiving a 3D ultrasound image including a cardiac region using an ultrasound probe at the beginning of the cardiac procedure or directly from the ultrasound probe in real time during the cardiac procedure, wherein the 3D ultrasound image comprises a transesophageal echo, TEE, or intracardiac echo, ICE; means for registering the 3D ultrasound image to a 3D coordinate system of the C-arm image acquisition system; means for detecting a cardiac structure of interest in the registered 3D ultrasound image; and means for automatically determining an angulation of the C-arm image acquisition system based on the detected structure of interest in the registered 3D ultrasound image; wherein the means for registering the 3D ultrasound image to a 3D coordinate system of the C-arm image acquisition system comprises: means for detecting a position of an ultrasound probe in a 2D x-ray image acquired by the C-arm image acquisition device ; means for estimating a pose of the ultrasound probe in the 3D coordinate system of the C-arm image acquisition device based on the detected position of the ultrasound probe in the 2D x-ray image using a probabilistic boosting tree; and means for registering the 3D ultrasound image to the 3D coordinate system of the C-arm image acquisition device based on the estimated pose of the ultrasound probe in the 3D coordinate system of the C-arm image acquisition device . means for detecting a position of an ultrasound probe in a 2D x-ray image acquired by the C-arm image acquisition device ; means for estimating a pose of the ultrasound probe in the 3D coordinate system of the C-arm image acquisition device based on the detected position of the ultrasound probe in the 2D x-ray image using a probabilistic boosting tree; and means for registering the 3D ultrasound image to the 3D coordinate system of the C-arm image acquisition device based on the estimated pose of the ultrasound probe in the 3D coordinate system of the C-arm image acquisition device . <EOS>