Role of Autonomic Nervous System in the Pathogenesis of Prinzmetal's Variant Form of Angina

Abstract

In ten patients with Prinzmetal's variant form of angina the effects of various drugs were assessed: subcutaneous injection of methacholine (10 mg), atropine (0.7 mg), and epinephrine (0.7 mg); intravenous infusion of isoproterenol (20-25 µg/min); and in the three of the above patients who were having recurrent spontaneous attacks at the time of the examination, oral administration of atropine (0.6-1.2 mg), propranolol (30-90 mg), and phenoxybenzamine (10 mg in one patient). Master's triple two-step test and selective coronary arteriography were done on all the patients. In the three patients who were having spontaneous attacks at the time of the examination, the administration of methacholine induced the attacks and that of atropine suppressed the attacks. Epinephrine induced the attacks in two patients and propranolol was without effect in suppressing the attacks. Phenoxybenzamine (in one patient) suppressed the attacks. Neither Master's triple two-step test nor isoproterenol infusion precipitated the attacks, though heart rate increased to more than 110 beats/min and 160 beats/min respectively in all the patients. Coronary arteriograms were normal in seven of the ten patients. It is concluded that enhanced activity of the parasympathetic nervous system, which occurs at rest, is involved in the initiation of the attack by stimulating the sympathetic nerve which in turn probably induces coronary arterial spasm by way of activating alpha (vasoconstrictor) receptors present in the large coronary arteries.

Coronary artery spasm during exercise in patients with variant angina.

“…Over a recent 40-month period, 33 patients with variant angina were evaluated at the Montreal Heart Institute. At coronary arteriography, 20 of these patients had one or more fixed coronary stenoses >70% and 13 had normal coronary arteries or stenoses <70% of the arterial luminal diameter. These 13 patients all underwent treadmill exercise testing using 15 electrocardiographic leads according to the protocol outlined below.…”

Acute Myocardial Infarction Following Hormone Replacement in Hypothyroidism

“…[15][16][17] In addition, other than plaque rupture, vasospasm or an increase in myocardial oxygen demand may be possible mechanisms. 18,19) In this case, we used the usual protocol for hormone replacement, although more gradual replacement might be adequate for such an elderly patient. Conclusion : We experienced a case of acute myocardial infarction following hormone replacement in hypothyroidism.…”

Poor responsiveness of heart rate to treadmill exercise in vasospastic angina

“…In some patients with Prinzmetal's variant angina, the role of the autonomic nervous system in the pathophysiology of coronary spasm has been well established (Ricci et al, 1979;Yasue et al, 1974). Nevertheless, the predictive value of heart rate response to exercise in detecting the presence of vasospastic angina was unknown.…”

“…On the other hand, the role of the autonomic nervous system in the pathophysiology of coronary spasm has been well established in some patients with vasospastic angina (Ricci et al, 1979;Yasue et al, 1974). Autonomic nervous disturbance may contribute to a condition participating in provocation of coronary spasm.…”