102 ESTIMATION OF SYSTOLIC PRESSURE DIFFERENCE IN AORTIC AND PULMONARY STENOTIC LESIONS BY CONTINUOUS WAVE DOPPLER ECHOCARDIOGRAPHY

Abstract

Continuous wave Doppler (CWD) echo has become progressively useful in estimating the systolic pressure gradient (SPG) in stenotic lesions. To determine the reliability of CWD in estimating SPG, we evaluated 34 patients (pts), 16 with aortic (A) and 19 with pulmonary (P) stenosis (S) by CWD and cardiac catheterization (CC). Pts ages ranged 7-216 months (mean 69). All pts had CC and CWD within 24 hours. CWD gradient was estimated from maximum velocity distal to the obstruction and CC gradient from pull back pressure. CC peak (Pk) SG ranged 5-110 mmHg, (mean 41). SPG estimated by CWD ranged from 5-100 mmHg (mean 38). SPG measured by CWD and CC showed good correlation (R-0.88) in 34 pts. In our last 17 pts r was 0.95 due to improved technique. The difference between SPG by CWD and CC Pk SG varied from -42 to 16, (mean -3.0). CWD overestimated the SPG in 13/34 (3 > 6mmHg). CWD underestimated the SPG in 16/34 (in only 5 was the difference >10 mmHg). Presence of semilunar valve insufficiency or aortopulmonary shunt did not affect CWD reliability.

Conclusion: CWD accurately assesses SPG in AS and PS. Discrepancies occur between the 2 methods, the reasons for which my be: CWD measures simultaneous SPG while CC measures Pk SG. Pk SG in CC decreases slightly with the distance between the site of measurement and the site of obstruction due to Bernoulli effect. Presence of a catheter through a narrow orifice may overestimate Pk SG at CC, in severe stenosis. The equation used for estimating gradient by CWD is less accurate for mild stenosis.

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