Keywords Dobutamine;Metoprolol;Left circumflex artery;Stress;coronary artery disease;Doppler tissue imaging;velocity;strain;strain rate;isovolumetric phase;

• 多巴酚丁胺;美托洛尔;左回旋支;负荷;冠心病;组织多普勒;速度;应变;应变率;等容期;