 9. Have blood levels of ions that might affect ECG WNL magnesium 1.82 mgdL to 2.41 mgdL, calcium 8.5 mgdL to 10.5 mgdL, potassium 3.5 mEqL to 10.5 mEqL, and sodium 135 mEqL to 148 mEqL Have no family history of sudden cardiac death before age 40 