The aim of this study was to evaluate the safety and efficacy of QW7437, a new fluorocarbon-based transpulmonary myocardial echocardiographic contrast agent. QW7437 is an anionically charged 2% dodecafluoropentane emulsion molecule, similar to EchoGen, a contrast agent previously shown to be efficacious in providing myocardial opacification by means of venous injection. This new agent has theoretical potential to provide greater safety and efficacy as a result of (1) reduced adherence to the negatively charged vascular endothelium and (2) reduced microbubble coalescence. Myocardial contrast echocardiography was performed in 10 dogs to evaluate the safety and efficacy of this agent. QW7437 (0.05 ml/kg) was injected as an intravenous bolus during intermittent harmonic epicardial imaging. Hemodynamic variables including heart rate, blood pressure, pulmonary artery pressure, pulmonary capillary wedge pressure, cardiac output, and arterial blood gases were determined at baseline and serially after contrast administration. Left ventricular fractional area shortening the regional myocardial blood flow at rest and during hyperemia (adenosine 140 micrograms/kg/min) were measured before and after contrast echocardiography. QW7437 provided dense myocardial opacification which persisted for more than 2 minutes in all subjects. This prolonged contrast effect did not result in significant changes in any hemodynamic variables, left ventricular function, or myocardial blood flow. Future studies should address the potential of this agent for human use.