A40-year-old man presents with atrial flutter with 2: 1 atrioventricular (av) conduction, giving him a pulse of 150 per minute, which is perfectly regular. his blood pressure is 70/40 mmhg. he takes no medications regularly. you plan to provide him with urgent direct current cardioversion with conscious sedation. what would be an appropriate level of energy for cardioversion in order to restore sinus rhythm in this patient? a 10 joulesb 15 joulesc 50 joulesd 200 joulese 300 joulesf 360 joules