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| Home->COTW AMA Category 1 Credit for Physicians Only. ASRT CME is not available. |
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Case-of-the-Week Information
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The TEE shows MS and atrial fibrillation with SEC in the LAA but a clot or thrombus was not present. Atrial fibrillation has been associated with an increased morbidity and mortality which can almost double the risk for a cardiovascular complication (women more than men). AF is responsible for 15% of all strokes and increases the risk of a stroke by a factor of 5. Thromboembolism is the major etiology for a stroke. Medical therapy (coumadin) has been associated with a 50% and 84% failure rate in one and two years of therapy, respectively. Coumadin therapy also exposes a patient to the risks of hemorrhage. A Cox Maze 3 can be done by the cut and sew, radiofrequency, cryoablation, and microwave therapy. Essentially the atrial tissue is ablated such that the sources of atrial fibrillation are isolated from the atrium (left and right) and a single pathway from the SA node to the AV node is left behind. Most studies show a return to NSR in about 80% of patients long term. Therefore a Cox Maze 3 is indicated in this patient.
The MVA can be measured by planimetry, mean mitral valve gradient, mitral valve area by PHT, and mitral valve area by PISA. Planimetry was not performed in this case. Planimetry can be accurate if the correct view and angle across the mitral valve leaflets can be visualized. Mitral valve gradients are flow dependent. A high cardiac output may falsely increase the mitral valve gradient, whereas a low cardiac output may falsely lower the mitral valve gradient. PHT (Pressure Half-Time) can be falsely decreased by significant aortic regurgitation. MVA by PISA avoids the above complications but can be difficult to visualize and small errors can give false results. In one study the MVA by Gorlin formula correlated better with PISA than PHT, although atrial fibrillation lowered the correlation between Gorlin and PISA. Another study showed that when comparing PISA to PHT, atrial fibrillation had no effect. PISA and PHT were close in correlation, but, tended to under estimate the MVA when compared to planimetry. After baloon valvotomy, PHT is not accurate whereas PISA remained an accurate calculation for mitral valve area. When faced with conflicting results (MVG was 8 mmHg, the MVA by PHT is 0.68 cm2 and the MVA by PISA was 0.8 cm2) the accuracy of MVA by PHT or PISA is more likely a better indication of the severity of the MS than the MVG. A MVR should be considered in this patient. |
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This activity is approved by the American Society of Radiologic Technologists (ASRT) as sonography-related continuing education (CE). Credit(s) issued for successful completion of ASRT-approved CE activities are accepted by the American Registry of Diagnostic Medical Sonography, American Registry of Radiological Technologists, Cardiovascular Credentialing International and Canadian Association of Registered Diagnostic Ultrasound Professionals. Contact the applicable registry for additional information / restrictions on their acceptance of ASRT CE credit.
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