Rate corrected systolic time intervals and Valsalva manoeuvre.

Measurements of left ventricular systolic time intervals during the Valsalva manoeuvre have been made in IO normal subjects, 5 patients with ischaemic heart disease before and after treatment with a beta adrenergic blocking drug, and 5 patients with cardiomyopathy. The individual relation between the heart rate and the left ventricular ejection time was established in the normal subjects during the intravenous infusion of atropine sulphate. The regression equations obtained were used to eliminate the effects of the changing heart rate on the ejection time during the Valsalva manoeuvre. Following this correction a consistent pattern emerged related to the changes in stroke volume known to occur during the Valsalva manoeuvre. In the presence of impaired myocardialfunction there was no significant fall in the left ventricular ejection time during the strain period. The overshoot, seen in normal subjects, in the corrected ejection time ratio after release of the strain is also lost. After beta adrenergic receptor blockade the post-release overshoot was blocked, and in addition there was an increase in the resting levels of the uncorrected ventricular ejection time which cannot be explained solely on the basis of the fall in heart rate observed after beta adrenergic blockade. It is suggested that this noninvasive technique may provide a useful alternative to direct arterial pressure recording in the assessment of the cardiovascular and autonomic responses to the Valsalva manoeuvre.