I took the PCCN and failed by 9 points. I studied on & off for a month but I did not dedicated a lot of time like I should have. I dedicated two days to solid studying prior to the test. I used David woodruff PCCN cd's very helpful & a ACCN PCCN book. You might want to know the differences between hyper/hypo kalemia & calemia, ABG's also knowing which leads correspond to the areas of the heart, know st segments changes. Prolonged QT interval & the causes. The ethical is 20% but common sense. Know your DKA. Look over the blue print From PCCN that the ACCN has majority of that is on cardio & pulmo for sure you want to know. Best of luck!