| Popis: |
The curve which expresses the relation between heart cycle length and the duration of the Q-T interval is logarithmic. It may be represented by the general formula Q-T = K log [10(C + k)], in which C is the cycle length (R-R) in seconds. K and k are constants. The formula for women between the ages of 15 and 32 years, inclusive, is obtained by using K = 0.385 and k = 0.07. The formula for younger men, and for children after early infancy, is derived by using K = 0.375 and k = 0.07. In these cases a slight change in both constants may possibly yield somewhat better agreement, but it is convenient and introduces a hardly appreciable error to use k as for women. To patients 45 years of age, or older, the same formula applies, but with a K of 0.380 for men and 0.390 for women. The upper limits of the normal Q-T interval may be expressed by the formulas previously published, 8 with allowance for personal variations in the technique of making the Q-T measurements. |
