Transesophageal color Doppler echocardiography of the normal St. Jude Medical mitral valve prosthesis

Prosthetic heart valves: Types and echocardiographic evaluation

In the last five decades multiple different models of prosthetic valves have been developed. The purpose of this article is to provide a comprehensive source of information for the types and the echocardiographic evaluation of the prosthetic heart valves.

Hemodynamic evaluation of normally functioning Sulzer Carbomedics prosthetic valves

The Sulzer Carbomedics prosthetic heart valve (CP) is a commonly used mechanical valve in clinical practice. In the present study, we used conventional and color Doppler echocardiography to assess the hemodynamics of normally functioning CP in the aortic (n = 73) and mitral (n = 127) positions. Our findings demonstrate no significant correlation of Doppler-measured peak and mean pressure gradients and effective orifice area with implanted valve size and actual orifice areas, measured directly by the manufacturer for CPs in both the mitral and aortic positions. However, it is still useful to measure effective orifice area by Doppler because a value in the normal or nonstenotic range points to an unobstructed prosthesis in the aortic or mitral position, in the absence of poor left ventricular ejection fraction. A value in the stenotic range could mean a normally functioning or obstructed prosthesis and, therefore, may need further investigation, such as assessment of valve leaflet motion by transthoracic or transesophageal echocardiography or fluoroscopy. Valve regurgitation as evaluated by color Doppler flow mapping was mild in practically all CPs in the aortic position, and in the majority of CPs in the mitral position.

Intraoperative echocardiographic detection of regurgitant jets after valve replacement

BACKGROUND

Paravalvular jets, documented by intraoperative transesophageal echocardiography, have prompted immediate valve explantation by others, yet the significance of these jets is unknown.

METHODS

Twenty-seven patients had intraoperative transesophageal two-dimensional color Doppler echocardiography, performed to assess the number and area of regurgitant jets after valve replacement, before and after protamine. Patients were grouped by first time versus redo operation, valve position and type.

RESULTS

Before protamine, 55 jets were identified (2.04+/-1.4 per patient) versus 29 jets after (1.07+/-1.2 per patient, p = 0.0002). Total jet area improved from 2.0+/-2.2 cm2 to 0.86+/-1.7 cm2 with protamine (p<0.0001). In all patients jet area decreased (average decrease, 70.7%+/-27.0%). First time and redo operations had similar improvements in jet number and area (both p>0.6). Furthermore, mitral and mechanical valves each had more jets and overall greater jet area when compared to aortic and tissue valves, respectively.

CONCLUSIONS

Following valve replacement, multiple jets are detected by intraoperative transesophageal echocardiography. They are more common and larger in the mitral position and with mechanical valves. Improvement occurs with reversal of anticoagulation.

Characterization of normal leakage flow of monostrut tilting disk prosthetic mitral valves by multiplane transesophageal echocardiography

To assess normal prosthetic mitral valve function, multiplane transesophageal Doppler echocardiographic studies were performed on 22 patients with Monostrut tilting disk valves. Mean follow-up after implantation was 63 +/- 12 months. Two holosystolic red low-velocity regurgitant jets were detected in all but one case. The length of these jets ranged from 0.8 to 6.9 cm and the area ranged from 0.5 to 10.1 cm2 in various planes. The origin of the jets was inside the rings of the prosthetic valves and started with a mosaic spot of 2 mm maximum diameter. In this mosaic spot, jet velocity by the high pulse-repetition frequency mode measured greater than 4 m/sec. Thin, high-velocity regurgitant jets originating outside the sewing ring were present in three cases. In one case we found a high-velocity turbulent jet originating outside the ring corresponding to a paravalvular regurgitation of moderate degree. The low-velocity jets were obscured in the patient with moderate paravalvular leak but not in patients with trivial paravalvular leaks.

Echocardiography and Doppler assessment of prosthetic heart valves with transesophageal echocardiography

This article examines the use of transesophageal echocardiography (TEE) in the assessment of prosthetic heart valves. A summary of the commonly used artificial valves and their physiologic regurgitant flow patterns, as identified by color Doppler imaging, is presented. The hemodynamic evaluation of prosthetic valve stenosis using Doppler techniques is reviewed, and the diagnostic utility of TEE in identifying the complications of cardiac prostheses is discussed.

Transesophageal echocardiography for the diagnosis and management of nonobstructive thrombosis of mechanical mitral valve prosthesis

BACKGROUND

Diagnosis of a mechanical mitral valve prosthesis thrombosis is currently made with transthoracic Doppler echocardiography and occasionally with fluoroscopy. However, identifying a thrombus on a valve prosthesis may be difficult, especially if the thrombus is nonobstructive. To prospectively define the role of transesophageal echocardiography for identification of nonobstructive thrombi, we studied a series of patients in whom the prosthetic valve was considered to function normally on clinical examination and transthoracic echocardiography.

METHODS AND RESULTS

One hundred fourteen consecutive patients with mechanical mitral valve prosthesis were investigated by both transthoracic echocardiography and transesophageal echocardiography. These examinations were performed for recent systemic emboli (15 patients), fever of unknown etiology (11 patients), routine postoperative evaluation (56 patients), and other reasons (32 patients). Based on transthoracic echo diagnosis, all prostheses were considered normal. Yet, in 20 patients transesophageal echocardiography revealed the presence of a 2- to 15-mm-long mobile thrombus localized on the atrial surface of the prosthesis. When compared with the remaining 94 patients with no visible thrombi, there was no significant difference between the two groups in terms of incidence of atrial fibrillation (65% versus 52%), left atrial size (48 +/- 9 versus 51 +/- 13 mm), left ventricular end-diastolic diameter (49 +/- 10 versus 51 +/- 13 mm) and fractional shortening (28 +/- 9% versus 31 +/- 10%), presence of spontaneous contrast to the left atrium (40% versus 41%), transprosthetic mean pressure gradient (4.0 +/- 1.4 versus 3.9 +/- 1.5 mm Hg), or the type of prosthesis used. After we discovered a nonobstructive thrombosis, patients were treated with heparin (n = 9) or oral anticoagulation (n = 11). The presence of a localized thrombus was confirmed in 3 patients who were operated on. In the present study, evolution appeared to depend on thrombus size: of 14 patients exhibiting a small (< 5 mm) thrombus, 10 had an uneventful course, whereas 5 of 6 patients with a large (> or = 5 mm) thrombus developed complications or died.

CONCLUSIONS

Transesophageal echocardiography appears to be a reliable method to diagnose thrombi on a mechanical mitral valve prosthesis, even when transthoracic Doppler echocardiographic parameters appear to be normal. Transesophageal echo assessment of thrombus size may be helpful in deciding whether a patient with mitral prosthesis should be treated by anticoagulation, thrombolysis, or valve rereplacement.

Long-term follow-up of mitral paraprosthetic regurgitation by transesophageal echocardiography

Paravalvular regurgitation (PVR) is an uncommon complication of mitral valve replacement (MVR). Although severe PVR is almost always repaired immediately when recognized during surgery, there are little data available on the management of patients with mild and moderate PVR. This study includes eight patients with mild (n = 6) and moderate (n = 2) PVR identified by transesophageal echocardiography at the time of MVR who were treated conservatively. Clinical and echocardiographic follow-up was obtained at a mean of 16.3 months. Two of six patients with mild PVR at the time of MVR and two of two patients with moderate PVR at the time of MVR deteriorated clinically and echocardiographically over time. We suggest that moderate PVR should be corrected at the time of valve-replacement surgery, if this can be performed without high operative risk. Mild PVR should probably also be repaired, if this can be performed at low risk, because some will progress. Patients left with mild PVR after surgery, or patients in whom PVR is recognized only after surgery, should be followed up carefully with serial clinical and echocardiographic examinations.

Mobile strands are frequently attached to the St. Jude Medical mitral valve prosthesis as assessed by two-dimensional transesophageal echocardiography

Two-dimensional transesophageal echocardiographic findings are reported in 13 patients with structurally and functionally normal St. Jude Medical bileaflet mitral valve prostheses. Multiple mobile linear echogenic densities attached to the pivot of the prosthesis were present in 9 of 13 patients. These densities may represent fibrin strands. These mobile strands alternatively resolve and reform over a period of 5 to 14 months after mitral valve replacement. No adverse clinical events were attributable to these prosthetic mitral valve strands. We conclude that mobile stands are frequently attached to the structurally and functionally normal St. Jude Medical mitral valve prosthesis. The clinical significance of these prosthetic mitral valve strands requires clarification.