Jackman WM, Friday KJ, Anderson JL, Aliot EM, Clark M, Lazzara R.The duration of the electrical systole, Q-T, in acute rheumatic carditis in children. An analysis of the time-relations of electrocardiograms. American journal of physiology, 1919: 139-140 Effect of pulse rate on the length of systoles and diastoles in the normal human heart in the standing position. A demonstration on man of electromotive changes accompanying the heart’s beat. In doing so, they updated Bazett’s original formula: Bazet, 1920ġ947 – Taran and Szilagyi related QT prolongation to acute rheumatic carditis in children. The normal value for k is 0.37 for men and 0.40 for women. The duration of the ventricular complex in an electrocardiogram is in the normal heart a function of the pulse rate, and may be determined by the formula: Systole = k √ cycle. The (Lombard, Cope 1919) results are confirmed by the figures here reported, in spite of the difference in the method employed, and I had independently arrived at the same relationship of systole to the square root of the cycle before the publication of their results. Waller gives values for the duration of mechanical systole with different heart rates, and it will be seen that almost exactly similar figures are obtained by calculation from the formula Systole = k √ cycle, where K has a value of 0.343. He then reviewed electrical and mechanical data from Weitz, Wiggars, Lewis, Buchanan, Kraus and Nicholai to confirm his calculations. He demonstrated that the period of mechanical contraction (systole) was shortened at faster heart ratesġ919 – Lombard WP and Cope OM recorded measurements of the carotid pulse in patients standing, lying and sitting and following exercise to derive an equation for measuring the duration of systole.ġ920 – Bazett used Waller’s 1891 data to create a formula which could estimate/calculate the duration of systole with varying pulse rates.
1891 – Augustus Desiré Waller provided a series of values for the duration of mechanical systole with different heart rates.
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