[Diagnosis of prosthetic mitral valve regurgitation by Doppler color flow imaging using right parasternal approach: a comparative study with transesophageal method].
Doppler color flow imaging is a useful tool in evaluating mitral regurgitation (MR). However, it is frequently difficult to assess prosthetic valve MR by the conventional transthoracic approach using left parasternal or apical echo-windows, because of the interception of ultrasound by the prosthesis or artifacts produced by its motion. The purpose of this study is to determine the usefulness of the "right" parasternal approach (RPA) in the echo diagnosis of prosthetic MR. Six patients with pathological prosthetic MR determined by transesophageal approach (TEA) were studied. Transthoracic echo was performed using both the RPA and the conventional approach, and the presence or absence and the extent of MR signals by these transthoracic approaches were compared with those by TEA. Prosthetic MR was detected in five of six patients by the RPA and the extent of MR signals by the RPA was very similar to that by TEE in each of the five patients. MR could not be detected by the RPA only in one patient, whose MR was estimated to be very mild by TEE. By the conventional approach, MR could not be detected in three patients and the degree of MR was significantly underestimated in two of the remaining three patients. Thus, the transthoracic RPA is often as useful as TEA in diagnosing prosthetic MR, which is often undetectable or underestimated by the conventional approach. Because the RPA is less invasive than TEA, the RPA should be encouraged in patients with suspected prosthetic mitral valve dysfunction.