Role of Adenosine in Pathogenesis of Syndrome X: Assessment With Coronary Hemodynamic Measurements and Thallium-201 Myocardial Single-Photon Emission Computed Tomography

Abstract

Patients with syndrome X with abnormal exercise scintigrams have high susceptibility to myocardial ischemia during exercise or pharmacologic stress tests, probably owing to reduced coronary flow reserve. A heterogeneous response to endogenous adenosine may contribute to scintigraphic perfusion abnormalities and myocardial ischemia during exercise in this subset of patients with syndrome X.

Digital Assessment of Endothelial Function and Ischemic Heart Disease in Women

“…Then, 50 g of acetylcholine was injected into the right coronary artery, followed by angiography. At baseline and acetylcholine-induced coronary spasm or 1 min after the maximum dose of acetylcholine was injected into the left coronary artery, paired samples of 2 ml of blood were collected simultaneously from the main trunk of the left coronary artery and coronary sinus to measure the myocardial lactate extraction rate, as reported previously (20).…”

Relation between transcardiac gradient of VEGF and coronary flow response in humans

“…Furthermore, the present study showed that the transcardiac gradient of plasma VEGF levels was decreased in the patients with cardiac syndrome X compared to the control subjects. Although pathogenic mechanism for cardiac syndrome X remains unclear, endothelium-dependent and/or-independent vasomotor dysfunction in resistance coronary arteries has been reported to play a pathogenetic role in this disease [13][14][15][16]. In fact, the present patients with cardiac syndrome X also had a blunted response of myocardial blood flow to ACh.…”

“…Thus, the decrease in myocardial production of VEGF may represent an underlying mechanism for the functional and structural abnormalities of coronary microcirculation in some patients with cardiac syndrome X, although cardiac syndrome X has extremely heterogeneous mechanisms [14][15][16]. Another feature of cardiac syndrome X is an enhanced cardiac pain perception [13][14][15][16]. Although the cause of the neural abnormality in cardiac syndrome X is also poorly understood, it is worth noting that VEGF has direct neuro-protective effects [26,27].…”

“…However, it remains unclear whether endogenously expressed VEGF in the myocardium modulates microvascular vasomotor function in human coronary artery. Cardiac syndrome X, characterized by angina pectoris, a positive exercise stress test, and a normal coronary angiogram, has been shown to exhibit an impaired coronary flow reserve [13][14][15][16]. Furthermore, there are also structural capillary abnormalities in myocardium in some patients with cardiac syndrome X [17,18].…”

Adenosine-Induced Coronary Artery Spasm: A Case Report

“…This is added to a predisposition of vulnerable vessels (coronary hypersensitivity). However, the exact mechanism of coronary vasospasm is still unclear [7,8]. The role of the autonomic nervous system is controversial.…”