The purpose of this protocol is to study the reproducibility of strain rate (SR) echocardiography in normal volunteers and patients with cardiovascular disease. Tissue Doppler ultrasound is a technology which has been validated for the analysis of global and regional left ventricular function and strain and SR measurements are derived from tissue Doppler imaging (TDI) data. Over the last few years, several improvements in echo machine hardware and software have facilitated the rapid acquisition and analysis of tissue Doppler data, and therefore, strain and strain rate information has become easily accessible. Recent publications have demonstrated the usefulness of these techniques in the analysis of systolic and diastolic function of the left ventricle, and in the detection of regional wall motion and ischemia. Several protocols recently initiated in the Cardiovascular Branch involve echocardiographic imaging and include applications of TDI as their primary or secondary endpoints. Therefore, the purpose of this protocol is to allow development of standardized acquisition and analysis methods of TDI for our cardiology protocols and to evaluate the reproducibility of TDI, SR, and strain measurements.