A comparison of synthetic aperture imaging using spherical and plane waves with low number of emission events is presented. For both wave types, a 90 degree sector is insonified using 15 emission events giving a frame rate of 200 frames per second. Field II simulations of point targets show similar resolution of approximately one wavelength radially and one degree angularly for both wave types. The use of spherical waves is found to have higher signal strength and better cystic resolution than plane waves. Measurements on wires in water yield similar results to simulations with similar resolution between the two wave types but better cystic resolution for spherical waves. Measurements on tissue mimicking phantoms show that both wave types penetrate down to 11 cm. Intensity measurements show an I_spta.3 of 18.4 mW/cm² for spherical waves and 22.7 mW/cm² for plane waves. The derated MI is 0.43 for spherical and 0.70 for plane waves. All measures are well within FDA limits for cardiac imaging. In-vivo images of the heart of a healthy 28-year old volunteer are shown.