The Mechanical Consequences of Anomalous Atrioventricular Excitation (WPW Syndrome)

Abstract

The mechanical consequences of anomalous atrioventricular excitation were studied in 12 patients by means of phonocardiograms, carotid pulse tracings, and in one instance, by data from cardiac catheterization. Three of these patients were also observed during normal conditions so that they supplied their own control data.In five instances mechanical anomalies were detectable as a consequence of the electrocardiographic abnormality. These anomalies were complex and consisted in one case of early onset and completion of ejection on both sides, and in another case of early completion on the left side. In three instances there was late activation on the contralateral side and possibly on the homolateral side as well.The remaining cases exhibited no such abnormalities by the methods studied, and in one subject this is illustrated with records made during both anomalous and normal conduction.The literature pertaining to this problem is critically reviewed, and an attempt is made to interpret both the previous and the present observations. The divergent nature of the observations suggests that the effect of anomalous excitation on the mechanics of the heart is the resultant of a number of variables, including the transmission time through the atrioventricular node and the site of entry of the anomalous focus.It is possible that the atrioventricular node does not function in some cases in which Wolff-Parkinson-White conduction is always present and it is not possible to induce normal beats with drugs, exercise, or respiratory maneuvers.