An ultrasound imaging system for determining stroke volume of a heart, comprising: an input for receiving ultrasound data of the heart acquired by an ultrasound transducer unit; and a controller adapted to: perform an initial assessment procedure in which initial ultrasound data is acquired using the transducer unit, and a Doppler processing technique is applied to the initial ultrasound data to determine presence or absence of a regurgitant blood flow from a ventricle to an atrium of a heart captured in the initial ultrasound data; responsive to determining absence of regurgitant flow, implement a first imaging procedure in which: the transducer unit is controlled to acquire 3D ultrasound image data at only an end-systolic time point and end-diastolic time point of a cardiac cycle of the heart, an image segmentation procedure is applied to the 3D ultrasound image data to determine a volume of said ventricle of the heart at each of said time points, and stroke volume is determined by calculating a change in said volume between said time points; responsive to determining presence of a regurgitant flow, implement a second imaging procedure in which stroke volume is determined by: controlling the transducer unit to acquire ultrasound data across a full duration of one or more cardiac cycles, and applying a further Doppler processing technique to said ultrasound data to identify a total blood flow out of said ventricle of the heart during each of the one or more cardiac cycles; and generate output information based on the determined stroke volume. an input for receiving ultrasound data of the heart acquired by an ultrasound transducer unit; and a controller adapted to: perform an initial assessment procedure in which initial ultrasound data is acquired using the transducer unit, and a Doppler processing technique is applied to the initial ultrasound data to determine presence or absence of a regurgitant blood flow from a ventricle to an atrium of a heart captured in the initial ultrasound data; responsive to determining absence of regurgitant flow, implement a first imaging procedure in which: the transducer unit is controlled to acquire 3D ultrasound image data at only an end-systolic time point and end-diastolic time point of a cardiac cycle of the heart, an image segmentation procedure is applied to the 3D ultrasound image data to determine a volume of said ventricle of the heart at each of said time points, and stroke volume is determined by calculating a change in said volume between said time points; responsive to determining presence of a regurgitant flow, implement a second imaging procedure in which stroke volume is determined by: controlling the transducer unit to acquire ultrasound data across a full duration of one or more cardiac cycles, and applying a further Doppler processing technique to said ultrasound data to identify a total blood flow out of said ventricle of the heart during each of the one or more cardiac cycles; and generate output information based on the determined stroke volume. perform an initial assessment procedure in which initial ultrasound data is acquired using the transducer unit, and a Doppler processing technique is applied to the initial ultrasound data to determine presence or absence of a regurgitant blood flow from a ventricle to an atrium of a heart captured in the initial ultrasound data; responsive to determining absence of regurgitant flow, implement a first imaging procedure in which: the transducer unit is controlled to acquire 3D ultrasound image data at only an end-systolic time point and end-diastolic time point of a cardiac cycle of the heart, an image segmentation procedure is applied to the 3D ultrasound image data to determine a volume of said ventricle of the heart at each of said time points, and stroke volume is determined by calculating a change in said volume between said time points; responsive to determining presence of a regurgitant flow, implement a second imaging procedure in which stroke volume is determined by: controlling the transducer unit to acquire ultrasound data across a full duration of one or more cardiac cycles, and applying a further Doppler processing technique to said ultrasound data to identify a total blood flow out of said ventricle of the heart during each of the one or more cardiac cycles; and generate output information based on the determined stroke volume.