The investigators hypothesize that performance of fast-Fourier transformation on the raw Doppler signals obtained from ascending aortic blood flow will recreate the pulse wave Doppler trace visualized on modern echocardiography machines, and that this will allow for the measurement and recording of vascular flow waveforms

Currently there is no commercially available mechanism for the measurement of blood flow velocity waveforms non-invasively. Blood flow velocity waveforms require the use of invasive catheters, thus precluding clinical use. Such information would allow the researcher / practitioner the ability to continuously measure blood flow, pulse pressure, and the pulsatility index of any vascular structure accessible by ultrasound with minimal additional risk to the subject / patient. This data, when combined with arterial blood pressure data, could also be used to measure peripheral pressure volume loops as well as aortic vascular impedance, both of which cannot be currently measured in vivo.

The ability to measure blood flow velocity waveforms at high temporal resolution would provide clinicians with new tools for hemodynamic optimization (both a novel means of estimating myocardial oxygen consumption [pressure volume area] as well as afterload [aortic vascular impedance]) and researchers with the ability to conduct hemodynamic experiments that were not previously possible. This work will serve as the foundation for several other related projects which depend on the ability to continuously record blood flow velocity waveforms.

Inclusion Criteria:

• 18-65
• Healthy

Exclusion Criteria:

• Cannot visualize ascending aorta with ultrasound

Healthy subjects 18-65