Apparatus for ablating tissue of a subject, the apparatus comprising: a reflection-facilitation element (20; 30; 700) comprising: an inflatable element, configured to be placed at a first side of the tissue of the subject, the inflatable element being flattened and having a thickness that is smaller than a length and smaller than a width of the inflatable element when inflated and not externally constrained; and an introducer, coupled to the inflatable element, and being configured to deliver a fluid to the first side of the tissue of the subject, such that a portion of the fluid is disposed within the inflatable element, and another portion of the fluid is disposed outside of the inflatable element; an ultrasound tool, comprising at least one ultrasound transducer, configured to be placed at a second side of the tissue of the subject, and to apply ultrasound energy such that at least a portion of the applied energy is reflected by the fluid; and a first electrode, disposed on a first side of the inflatable element anda second electrode, electrically coupled to the first electrode, wherein the first and second electrodes (704, 706) are configured to facilitate defibrillation of the heart of the subject, and wherein the second electrode is disposed on a second side of the inflatable element, and wherein the first and second electrodes (704, 706) are configured to conduct electricity from the first side to the second side of the inflatable element. a reflection-facilitation element (20; 30; 700) comprising: an inflatable element, configured to be placed at a first side of the tissue of the subject, the inflatable element being flattened and having a thickness that is smaller than a length and smaller than a width of the inflatable element when inflated and not externally constrained; and an introducer, coupled to the inflatable element, and being configured to deliver a fluid to the first side of the tissue of the subject, such that a portion of the fluid is disposed within the inflatable element, and another portion of the fluid is disposed outside of the inflatable element; an inflatable element, configured to be placed at a first side of the tissue of the subject, the inflatable element being flattened and having a thickness that is smaller than a length and smaller than a width of the inflatable element when inflated and not externally constrained; and an introducer, coupled to the inflatable element, and being configured to deliver a fluid to the first side of the tissue of the subject, such that a portion of the fluid is disposed within the inflatable element, and another portion of the fluid is disposed outside of the inflatable element; an ultrasound tool, comprising at least one ultrasound transducer, configured to be placed at a second side of the tissue of the subject, and to apply ultrasound energy such that at least a portion of the applied energy is reflected by the fluid; and a first electrode, disposed on a first side of the inflatable element anda second electrode, electrically coupled to the first electrode, wherein the first and second electrodes (704, 706) are configured to facilitate defibrillation of the heart of the subject, and wherein the second electrode is disposed on a second side of the inflatable element, and wherein the first and second electrodes (704, 706) are configured to conduct electricity from the first side to the second side of the inflatable element.