HEAD-UP TILT TEST COMBINED WITH ISOPROTERENOL INFUSION PROVOKES CORONARY VASOSPASTIC ANGINA

The association of the autonomic nervous system with coronary vasospas m has been controversial. The aim of the present study was to examine the involvement of the autonomic nervous system in coronary vasospasm by applying the head-up tilt (HUT) test to patients with coronary vaso spastic angina. Fifteen consecutive patients with coronary vasospastic angina and without significant organic coronary stenoses underwent th e HUT test. Prior to the test, coronary spasm was documented angiograp hically by using an intracoronary injection of acetylcholine or ergono vine. The HUT test was performed in the early morning and repeated in the afternoon if the test was positive in provoking angina pectoris an d syncope or presyncope. If the test was negative, it was repeated und er intravenous infusion of isoproterenol at a rate of 1-2 mu g/min. Th e HUT test under isoproterenol infusion in the morning provoked vasosp astic angina with syncope or presyncope in 9 of the 15 patients. In th e test-positive group, heart rate was significantly reduced (104+/-17 beats/min to 84+/-25 beats/min, p<0.05), which preceded a reduction in systolic blood pressure (158+/-25 mmHg to 125+/-17 mmHg, p<0.01), ang ina attack and syncope. The HUT test without isoproterenol infusion in the morning and the HUT test in the afternoon with or without isoprot erenol infusion failed to provoke angina. The heart rate reduction pre ceding reduced systemic blood pressure and anginal attack suggested th at parasympathetic nerve excitation plays an important role in coronar y vasospasm. The results also implied that the HUT test combined with isoproterenol infusion is useful for the provocation of coronary spasm .