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Is there a relation between the shape of the aortic outflow velocity profile and contractile function in coronary artery disease? A dobutamine stress echo study.

From isolated cells, it was suggested that chronic ischemia decreases, but prolongs contraction. Additionally, severe aortic stenosis shows, besides higher, often prolonged outflow velocities. Outflow velocities represent the pressure gradient between LV and aorta, thus are influenced by either of them. However, a dynamically increasing resistance in the vessel tree would reduce late velocities while high late velocities should be related to prolonged contraction. Thus, we assumed a relationship between the morphology and duration of aortic outflow velocities and myocardial function in coronary artery disease (CAD). We studied 126 pts who underwent a routine dobutamine stress echo (DSE). At baseline and peak stress, CW Doppler traces of aortic flow were acquired. All traces were visually divided into 2 groups: normal and broadened. Fig 1 middle shows a typical normal trace, triangular in shape, with the peak occurring early. Left shows typical broadening with a much more rounded shape and later peak. Traces with a clear dynamic intra-cavity gradient at peak stress were omitted ; peak dose could not be reached in 45/126 pts. 53/126 pts had an angiographically confirmed stenosis in at least one coronary. 25/53 (47%) showed a broad outflow trace. This did not change at peak stress. Of 12/126 patients with unconfirmed CAD and positive DSE, 2 (17%) had a broad spectrum. At peak stress 4/8 (50%) were broad. 61/126 pts had no evidence of CAD and normal DSE. Of these, 7/61 (11%) were broad which increased to 12/26 (46%) at peak stress. The broadening in these apparently normal pts was often induced by a (small) dynamic gradient (fig 1 right). Thus, in the presence of CAD, there seems to be a broadening of the aortic outflow profile. This might be related to a reduction in global myocardial contractility.

Doppler echocardiography; mathematical modeling; aortic outflow profile; coronary artery disease; contractile function

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