Cardiodynamic changes during passive tilt and acute nitrate therapy.

In six patients with normal left ventricles and seven post-myocardial infarction patients cardiodynamic changes during tilt and acute nitrate medication were investigated. The conductance catheter was used for on-line registration of left ventricular volumes and a microtip manometer for high-fidelity pressure recordings. We analysed left ventricular end-diastolic volume index (EDVI) ejection fraction (EF), cardiac index (CI), heart rate (HR), end-systolic pressure (ESP) and end-diastolic pressure (EDP) in the supine position and 30 s after passive upright tilt. Supine and standing measurements were performed without medication and 2 min after acute nitrate medication (0.8 mg sublingual nitroglycerin). After unloading by upright tilt there was a similar reduction of average EDVI in the control group (-18 +/- 7 ml.m2) and in the post-infarction group (-21 +/- 18 ml.m2). The effect of nitroglycerin on EDVI (-12 +/- 4 ml.m2 control, -7 +/- 6 ml.m2 post-infarction) was less than the effect of upright tilt. EF in the control group improved by +8 +/- 5% (in absolute values) during passive tilt; the combined effect of tilt and nitrate was +12 +/- 6% EF (p < 0.05). In the post-infarction group EF did not change significantly during tilt and/or nitrate therapy. In the patients with normal regional ventricular function, CI during tilt was maintained at a constant level. In the post-infarction group the reduction in CI was not significant. Although the reduction in EDVI was similar in the control and infarction groups, the infarction group did not respond to the cardiodynamic change by increasing EF.(ABSTRACT TRUNCATED AT 250 WORDS)