Answer and Explanation 20

20.  The correct answer is B.  This rhythm is torsades which is caused by low magnesium.  It is important not only to obtain a magnesium level but to treat it in a timely manner.  Potassium should also be checked.  Remember hypokalemia cannot be  effectively treated if the magnesium level is low.  Abnormal phosphorus and sodium levels will not produce rhythms such as this.