An arrhythmia is any disorder of your heart rate or rhythm. It means that your heart beats too quickly, too slowly, or with an irregular pattern. Most arrhythmias result from problems in the electrical system of the heart. If your arrhythmia is serious, you may need a cardiac pacemaker or an implantable cardioverter defibrillator (ICD). They are devices that are implanted in your chest or abdomen. A pacemaker helps control abnormal heart rhythms.
Generally speaking, the numbers refer to the parentages of Nitrogen, Phosphorus and Potassium, by weight, listed in this exact order and contained in the fertilizer. These numbers stand for the percentages contained within a specific package.
David Beaulieu. NPK stands for nitrogen, phosphorus, and potassium, the three nutrients that compose complete fertilizers (see below). You will encounter the letters, NPK (sometimes separated by hyphens) when reading the contents (analysis; see picture) printed on bags of fertilizer. The description of the fertilizer may not expressly say NPK (it may simply be implied), but you will at least see a series of three numbers, which correspond, respectively, to the nitrogen content, phosphorus content and potassium content of that fertilizer.