- waveforms are monophasic with a constant antegrade flow and no flow below the baseline.
- the waveform is typically parvus-tardus with a slow systolic upstroke and rounded systolic peak.
- less commonly there may be non-pulsatile flow with no systolic peak.
- the systolic peak is thought to be due to intrinsic residual myocardial reserve pumping some of the blood, whereas lack of a systolic peak is thought to occur when the left ventricle is simply acting as a passive conduit and all blood is being pumped by the device.
- peak systolic velocity is reduced.
These findings have been demonstrated diffusely in multiple arterial beds, including the carotid, vertebral, subclavian and common femoral arteries.
Spectral Doppler derived indices of intracardiac hemodynamics, measured as part of repeated comprehensive echocardiographic studies, are used to serially assess cardiac structure and function. Echocardiography is typically performed in the following settings 3;
- pre-operative survery
- perioperative monitoring
- conducted using a transesophageal approach
- allows continuous assessment of the positioning and angulation of the cannulae during introduction 4
- color flow Doppler (CFD) is also used to screen for the presence of the following, which may portend a complicated clinical course:
- post-surgical evaluation
- routine surveillance
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