Significance of shortening of the mean QRS duration of the standard electrocardiogram in patients developing peripheral edema

Abstract

An electrocardiographic syndrome was reported recently linking a gradual decrease in the QRS potentials of the standard electrocardiogram (ECG) with a parallel development of peripheral edema in patients with a critical illness of varying etiology. 1 In that study, a decrease in the sums of QRS amplitude of 12-lead ECGs (QRS) correlated well with weight gain (r 0.61, p 0.0005). Perusal of the daily ECGs from that study revealed gradual shortening of the mean QRS duration. To investigate this matter further, a documentation of the decrease in the mean QRS duration and an analysis of its relation with weight and QRS was carried out. The objectives of this study were: (1) to define whether mean QRS duration correlates with weight gain; (2) to determine whether it has any advantages when compared with QRS in predicting weight gain; and (3) to determine whether it provides a better indicator of weight gain when combined with QRS in a form of a product. Speculation as to the mechanism of decrease in the mean QRS duration consequent to weight gain is also included in this study. ••• The study population and the methods employed have been previously described. 1 For the purposes of this study, data from the consecutive series of 28 patients with peripheral edema admitted to our Coronary Care Unit in 1999 with a critical illness were reevaluated. The patients had daily weights and electrocardiographic tracings recorded. Information on percent change of weight from admission to the point of peak weight value, and half-weight gain were used as study parameters. The QRS and mean QRS duration and the percent change of QRS and mean QRS duration from admission to the peak weight and half-weight points were also considered. In addition, a composite variable consisting of the product of QRS and mean QRS duration of the corresponding ECG was included. QRS was calculated as the sum of the QRS complex amplitudes (highest positive lowest negative deflection) of all electrocardiographic leads, measured to the nearest 0.5 mm, using a magnifying glass and calipers (Figure 1). The average of measurements of 3 consecutive beats was used for ECGs of patients with atrial fibrillation. The Hewlett-Packard (now acquired by Royal