| Abstract: | The QT/QS2 ratio in seven 21-year-old men with a history of vasomotor lability was measured when they were resting supine and during orthostatic, Valsalva and diving reflex tests. The vasolability was characterized by an abnormal sympathicotonic heart rate (HR) response to the orthostatic test and vacillating inferoapical T waves in the ECG. The results of the vasolabile subjects were compared to those of seven fit control subjects of the same age. In spite of equal HR's in both groups the vasolabile subjects' QT/Q2 ratio constantly exceeded 1.00 during the whole test protocol and it was higher than of the controls (P = 0.04). The reversed QT/QS2 relationship in the test subjects seemed to be due both to a prolongation of the QT time and a shortening of the QS2 time. This difference prevailed throughout although the reaction pattern to autonomic stimulations was equal in both groups. We considered an inadequate neural control of the heart, possibly with metabolic and haemodynamic interactions, responsible for the prolongation of the electrical systole in relation to the electromechanical systole in the heart of the vasomotorically labile subjects. |
