Once prerenal and postrenal causes are ruled out, intrinsic renal failure is likely. Intrinsic ARF, caused by disease of the renal parenchyma, accounted for 69% of cases in the Madrid study. Acute tubular necrosis (ATN), the most common type of intrinsic ARF, accounted for 45% of all cases of ARF. Most of the following discussion is therefore focused on ATN; other types of intrinsic ARF have been reviewed in detail in studies by Glassock and colleagues.
Rhythm is the repetition or alternation of elements, often with defined intervals between them. Rhythm can create a sense of movement, and can establish pattern and texture.
Sinus rhythm. A sinus rhythm is any cardiac rhythm where depolarisation of the cardiac muscle begins at the sinus node. It is characterised by the presence of correctly oriented P waves on the electrocardiogram (ECG). Sinus rhythm is necessary, but not sufficient, for normal electrical activity within the heart.