High gradients after surgery?

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Well-known member
Jun 14, 2019
Wisconsin, USA
Regarding the mean gradient values of aortic mechanical valves (MPG), there is a fairly recent and suggestive study for brands ATS, BICARBON and ON-X. The measured values for valves between 18 mm and 25 mm at 6 months after surgery were 17.04±8.4 mmHg for ATS, 21.5±12.9 mmHg for BICARBON and 17.3±7.6 mmHg for ON-X.
For example, for ON-X: small valves (18-19 mm), MPG was most in the range 18-27 mmHg, for medium valves (22-23 mm) MPG was most in the range 9-18.5 mmHg and for the larger valves (24-25 mm) MPG was most between 7.5-8.5 mmHg. So, a value considered by some to be high (for example, 18 mmHg for a 19 mm valve) is actually a satisfactory value for that valve. Also, a MPG value of 24 mmHG is found in practice in small and even medium valves, although in the literature a value of 20 mmHG is considered high. More important are the functioning and dimensions of the heart.

Not sure about that article - first sentence: There are scarce data comparing different mechanical valves in the aortic position - gad, they've been publishing data on this stuff for decades. Then if you look at the chart (a .jpg), the 18/19 hovers around a average of 18mmHg or so and all the other sizes come in at 14mmHg or so, all with a large std. dev. so really two groups (small and a little bigger).

As I age I get more skeptical :unsure: .

Chuck C

Well-known member
Dec 5, 2020
@Chuck C not that close an eye on it, on the ascending aorta 2 more years till the next look so that’ll be 4 yrs unchecked, we have a public health system so I might pay for a scan later in the year for piece of mind.

4 years between echos for an aorta with a 4.0cm diameter seems much longer than appropriate.

This publication recommends echo imaging much more often than that:

"Serial Imaging
Patients should be followed up with serial imaging studies for surveillance. When a thoracic aortic aneurysm is first detected, it is typically not possible to determine the rate of growth. It is therefore appropriate to obtain a repeated imaging study 6 months after the initial study. If the aneurysm is unchanged in size, it is then reasonable to obtain an imaging study on an annual basis in most cases."

" However, should there be a significant increase in aortic size from one study to the next, the interval between studies should be decreased to 3 or 6 months (according to the aortic diameter). "

Also, this:

"Moreover, when patients with a bicuspid valve require aortic valve replacement surgery, we recommend prophylactic replacement of the ascending aorta if its diameter is 4 cm or greater, given that we now recognize that such patients would otherwise remain at high risk for subsequent aortic dissection."

This is something that also should be of interest, especially to those of us with bicuspid aortic valves:

"Cystic medial degeneration has been found to be the underlying cause of the aortic dilatation associated with a bicuspid aortic valve. In one study, 75% of those with a bicuspid aortic valve undergoing aortic valve replacement surgery had biopsy-proven cystic medial necrosis of the ascending aorta,"

This publication also recommends imaging with similar frequency:

"an early follow-up scan (6 months after initial TAA diagnosis) is recommended to assess for growth of the aneurysm in patients who have genetic conditions, and annually thereafter if measurements have been stable or more frequently if there is accelerated growth."

Last edited:


Jan 26, 2021
Romania, EU
so really two groups (small and a little bigger).

As I age I get more skeptical :unsure: .

"the objective of this study was to compare the EARLY hemodynamic changes after aortic valve replacement between ATS, Bicarbon, and On-X mechanical valves.
There was no difference in the postoperative aortic prosthetic mean pressure gradient between groups when stratified by valve size. The changes in the aortic prosthetic mean pressure gradient of the intraoperative period, at pre-discharge, and at six months were comparable between the three prostheses (P=0.08).
Multivariable regression analysis revealed that female gender (beta coefficient -0.242, P=0.027), body surface area (beta coefficient 0.334, P<0.001), and aortic prosthetic size (beta coefficient -0.547, P<0.001), but not the prosthesis type, were independent predictors of postoperative aortic prosthetic mean pressure gradient."

And I can add that even the early results of my Carbomedics Standard 23 mm Valve are within the limits of the study and the manufacturer's specifications (4 echocardiograms in 6 months after surgery).