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ASRT CME Not Available
 
Case-of-the-Week Information
The Case-of-the-Month is a presentation of one or more video loops to present an important topic in echocardiography. Please reveiw the image or video loops and then answer the questions below. After you have answered the questions you can view the explanation and obtain CME credit (if available).

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Loop Text Key  
Preop Preop TEE or TTE
Intraop An Intraop TEE
IntraopPreOp Intraop TEE before Operation
IntraopPostOp Intraop TEE after Operation
IntraopEnd Intraop TEE at End of Anesthesia
Post Op Postop TEE or TTE
Case of the Month Information Table
IntraopEnd is usually a TEE after the Operation and after some event occured to show a change in the TEE
High AVG after an Aortic Valve Replacement
Case#: 7
AMA CME Units: 0.25 Units
Estimated Time: 15 minutes
CME Requirements: Active CME Session and must be a paid, active subscriber to iTEE or advanced TEE AND have enough CME credits in your bank. AMA CME ONLY.
 
Presentation: 81 yo male, who weighed 83 kg and had a height of 168 cm, with history of a heart murmur. Preop TTE showed severe aortic stenosis with an AVA of 0.9 cm2. The patient underwent an AVR with a 21 mm Edwards pericardial valve. The IntraopPre AVR, IntraopPost AVR and the Postop TTE are shown below. Please review the IntraopPre AVR and IntraopPost AVR video loops and discuss the possible etiologies of the post AVR abnormality. What would you expect to find after an Edwards Pericardial valve that is 21 mm? What would be your recommendation to the surgeon after the AVR?

 
 
Loops:
 
 
 
Case Discussion/CME Questions
 
The patient presented with an AVA of 0.9 cm2 by preop TTE. The intraop preAVR TEE confirmed severe calcific aortic stenosis with a pAVG of 53 mmHg and a mAVG of 39 mmHg. The AVA was calculated at 0.89 cm2 and measured by 2D to be 0.89 cm2. There was LVH and a high LAP. The LVEF was 50%. The LVOT was 2.3 cm. TEE tends to slightly underestimate the AVG and AVA because of the angles when compared to TTE.

After the AVR with a 21 mm Edwards Pericardial valve the pAVG was 47 mmHg and the mAVG was 21 mmHg. After a 21 mm Edwards Pericardial valve the mAVG should be near 10 mmHg so there was a concern about:

  • SAM
  • Patient-Prosthetic Mismatch
  • Artifact
  • IHSS
  • Subaortic Stenosis
  • Intracavitary Gradient
  • Prosthetic Valve Dysfunction
  • Prosthetic Valve Malorientation
SAM and IHSS was not present on the AVLAX view. The CFD did not show any turbulence below the valve or in the LV cavity. The views of the AV showed proper orientation of the valve and proper seating of the valve. The leaflets, while difficult to visualize, where felt to be moving normally. There was no aortic regurgitation which suggested normal closure of the leaflets. The CWD of the AV was only during the expected ejection period and not pansystolic so a beam misdirection into an MR jet was ruled out.

A high post AVR gradient after an AVR could be due to high flow, since gradients are flow related, or due to a patient-prosthetic mismatch (PPM). The calculated AVA of the prosthetic valve was 1.45 cm2. His BSA was 1.9 m2 which calculated an effective orifice index area (EOIA) to 0.76 cm2/m2.

Patient-Prosthetic Mismatch (PPM) was first defined by Rahimtoola as any valve area that is less than a native valve area. However, PPM has since been  described by the effective orifice index area (EOIA) of a prosthetic valve as:

Patient-Prosthetic Mismatch
Severity Ref 1 Ref 2 Ref 3
 Mild  < 1.0 cm2/m2
> 0.85 cm2/m2  < 0.8 cm2/m2
 Moderate  < 0.9 cm2/m2  < 0.85 cm2/m2  
 Severe  < 0.6 cm2/m2  < 0.65 cm2/m2  

Gradients in prosthetic valves do not increase until the EOIA is < 0.85 cm2/m2-0.9 cm2/m2. Several studies have looked at the short and long term effects of PPM and the debate continues because after a PPM is recognized to place a larger valve into the patient an aortic root enlargement must be performed and the subsequent risks of aortic enlargement must be justified by the short and long term effects of PPM. Some studies have indicated that the mortality increases with increasing PPM although other studies have shown no correlation. There is ample evidence, however, that aortic root enlargement does increase mortality. As patients age, the mortality is most likely due to other factors rather than the PPM. Since mortality occurs, the difference in mortality as a person ages is less evident. Similar effects have been found with obesity. A patient with a high BMI will have less of a decrease in mortality than a patient with a lower BMI if PPM is not present. Age > 70 yrs old and a high BMI do not have increased mortality from PPM. LVH (and the loss of remodeling after an AVR) appears to increase the mortality in patients with PPM.

High gradient after aortic valve replacement, while worrisome, may not be very accurate. After ruling out other causes of a high AVG after an AVR, the AVG could be due to a high flow state. The ratio of the Vmax of the LVOT and athe AV pre and post AVR will indicate whether an obstruction still exists. Also the AVA can be calculated by the continuity equation. Gradients after an AVR can be due to the hyperdynamic state of the myocardium, fluid overload, and can be affected by ongoing ischemia of the heart, differences in heart preservation from cardioplegia, the hematocrit, vascular resistance, and a myriad of other factors - all of which change postoperatively. AVG tend to increase with the swelling, especially if stentless valves are used, and then falls as the edema resolves. One study looked at AVG after an AVR and found that AVG were not much better than flipping a coin in predicting postoperative AVG.  The AVA should be calculated after an AVR to measure the EOIA of the prosthetic valve.

In this patient it is interesting that we elected to not enlarge the aortic root/replace the aortic valve because the AVA was 1.45 cm2 and the EOIA was less than 0.85 cm2/m2 because of the risk involved and the patient was > 70 yrs old. A followup TTE indicated that the mean and peak gradient dropped almost to the levels that one would expect for a pericardial valve.
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