therosclerosis is a series of histopathological changes that includes intimal thickening, degenerative compositional changes of the medial layer (sclerotic change) and atheroma-formation (atherotic change). 1 The recent development of high-resolution Bmode ultrasonography has made it possible to detect and evaluate the atheromatous changes of the arteries, particulary the carotid artery. [2][3][4][5] However, despite these studies, methods that evaluate the sclerotic change of an artery, an early stage of atherosclerosis, have not been established. Vascular sclerotic changes increase vascular stiffness, and may disturb the vascular responses to a vascular relaxant. Although decreased elasticity of the arterial wall in the atherosclerotic carotid artery has been reported, 6-9 the carotid artery response to vascular relaxant has not been reported yet.Nitroglycerin (NTG), a relaxant of vascular smooth muscle, may change arterial elasticity. 10,11 If the change in elasticity of the atherosclerotic artery in response to NTG is different from that of the normal artery, evaluation of this response may be valuable in assessing atherosclerotic changes. The purpose of the present study was to determine whether the early atherosclerotic changes of the common carotid artery (CCA) could be evaluated by the response of vascular elasticity to NTG, where there was no ultrasonic atheromatous plaque. The vascular elasticity was expressed by vascular strain (VS) and pressure-strain elastic modulus (Ep). Moreover, the extent of atherosclerosis of the CCA has been shown to be strongly correlated with the extent of coronary artery disease (CAD). 12-16 Therefore, we also examined whether the decreased elasticity response of the CCA to NTG was associated with CAD.
Methods
Study SubjectsThe study was performed in 52 patients who were admitted for the evaluation of CAD (35 men and 17 women, aged from 45 to 74 years old ), and 9 normal male volunteers (aged from 23 to 27 years old) without risk factors for atherosclerosis such as hyperlipidemia, hypertension, glucose intolerance and smoking. Patients with frequent arrhythmias, congestive heart failure, congenital and acquired heart disease were excluded, because the hemodynamic abnormality of these diseases may affect the diameter change of the CCA. Patients with recent cerebrovascular attacks and a blood pressure difference between the bilateral brachial artery of greater than 10 mmHg were also excluded. Informed consent was obtained from every
Evaluation of the Early Stage of Carotid Atherosclerosis Using the Vascular Response to Nitroglycerin and High-Resolution UltrasonographyJpn Circ J 1998; 62: 494 -498 Cha-Po Lai, MD; Samon Koyanagi, MD**; Cheng-Kuang Shaw, DDS*; Akira Takeshita, MD**The purpose of this study was to determine whether the early stages of arterial atherosclerosis could be evaluated by the vascular response to nitroglycerin (NTG). The vascular elasticity of the common carotid artery (CCA) was evaluated at sites without atheromatous plaque using high-resolution ultr...