Doppler color flow mapping in the evaluation of prosthetic mitral and aortic valve function

Successful fibrinolytic treatment of prosthetic heart valve thrombosis using streptokinase

OBJECTIVES

This study aims to evaluate the clinical outcome of fibrinolytic treatment of prosthetic valve thrombosis (PVT) with 'streptokinase' as a first line treatment for these cases.

METHODS

The study group was 20 consecutive patients (10 females) diagnosed with PVT. The protocol for streptokinase administration was either accelerated (intravenous infusion of 0.5 million IU over 30 minutes followed by 0.15 million IU/h) or conventional (intravenous infusion of 0.25 million IU over 30 minutes followed by 0.15 million IU/h). Success of fibrinolytic therapy was defined as complete restoration of valve function in the presence or absence of complications.

RESULTS

Eighteen patients (90%) had mitral PVT and two (10%) had aortic PVT. Thrombolytic therapy with streptokinase was successful in all but one case, with a total mortality of four cases (20%). In PVT episodes, before streptokinase therapy, the prosthetic valve areas (in all cases, mitral and aortic positions) were 0.82 ± 0.21, 0.83 ± 0.21, and 0.73 ± 0.18 cm²; and the peak and mean transvalvular gradients were 38.7 ± 16.7 and 25.4 ± 8.7, 34.1 ± 8.8 and 23.2 ± 5.4, and 80.0 ± 14.1 and 45.0 ± 7.1 mmHg, respectively. After streptokinase therapy, the prosthetic valve area and peak and mean transvalvular gradients improved significantly (for all cases, mitral and aortic positions: valve area 2.17 ± 0.58, 2.21 ± 0.61, and 1.85 ± 0.07 cm², peak gradient 18.7 ± 11.0, 16.4 ± 7.7, and 39.0 ± 18.4, and mean gradient 9.6 ± 7.1, 8.2 ± 5.3, and 22.0 ± 11.3 mmHg, respectively; paired t-test, P<0.001 for pre- versus post-streptokinase infusion for all variables).

CONCLUSION

Fibrinolytic therapy using streptokinase was an effective therapeutic strategy for the management of PVT and is a reasonable alternative to surgery.

The role of echocardiography during mitral valve percutaneous interventions

Transesophageal echocardiography is routinely used to guide percutaneous interventions involving the mitral valve. Mitral balloon valvuloplasty for rheumatic mitral valve stenosis (MS) was the first percutaneous intervention to gain wide acceptance. New techniques have been developed to treat degenerative and functional mitral regurgitation (MR) as well as paravalvular mitral leak (PVML). This review describes the use of echocardiography for transcatheter treatment of MS, MR, and PVML.

Multimodality imaging in transcatheter aortic valve implantation and post-procedural aortic regurgitation: comparison among cardiovascular magnetic resonance, cardiac computed tomography, and echocardiography

OBJECTIVES

The purpose of this study was to determine imaging predictors of aortic regurgitation (AR) after transcatheter aortic valve implantation (TAVI) and the agreement and reproducibility of cardiovascular magnetic resonance (CMR), cardiac computed tomography (CCT), and transthoracic echocardiography (TTE) in aortic root assessment.

BACKGROUND

The optimal imaging strategy for planning TAVI is unclear with a paucity of comparative multimodality imaging data. The association between aortic root morphology and outcomes after TAVI also remains incompletely understood.

METHODS

A total of 202 consecutive patients assessed by CMR, CCT, and TTE for TAVI were studied. Agreement and variability among and within imaging modalities was assessed by Bland-Altman analysis. Postoperative AR was assessed by TTE.

RESULTS

Of the 202 patients undergoing TAVI assessment with both CMR and TTE, 133 also underwent CCT. Close agreement was observed between CMR and CCT in dimensions of the aortic annulus (bias, -0.4 mm; 95% limits of agreement: -5.7 to 5.0 mm), and similarly for sinus of Valsalva, sinotubular junction, and ascending aortic measures. Agreement between TTE-derived measures and either CMR or CCT was less precise. Intraobserver and interobserver variability were lowest with CMR. The presence and severity of AR after TAVI were associated with larger aortic valve annulus measurements by both CMR (p = 0.03) and CCT (p = 0.04) but not TTE-derived measures (p = 0.10). Neither CCT nor CMR measures of annulus eccentricity, however, predicted AR after TAVI (p = 0.33 and p = 0.78, respectively).

CONCLUSIONS

In patients undergoing imaging assessment for TAVI, the presence and severity of AR after TAVI were associated with larger aortic annulus measurements by both CMR and CCT, but not TTE. Both CMR and CCT provide highly reproducible information in the assessment of patients undergoing TAVI.

Transapical transcatheter aortic valve implantation: follow-up to 3 years

BACKGROUND

We performed the first human case of successful transapical transcatheter aortic valve implantation on a beating heart in October 2005, and therefore we have the longest follow-up on transapical aortic valve implantation in humans. We now report clinical and echocardiographic outcomes of transapical aortic valve implantation in 71 patients.

METHODS

Between October 2005 and February 2009, 71 patients (44 female) underwent transcatheter transapical aortic valve implantation with either 23- or 26-mm Edwards Lifesciences transcatheter bioprostheses. All patients with symptomatic aortic stenosis were declined for conventional aortic valve replacement owing to unacceptable operative risks and were not candidates for transfemoral aortic valve implantation because of poor arterial access. Clinical and echocardiographic follow-ups were performed before discharge, at 1 and 6 months, and then yearly. The mean follow-up was 12.9 +/- 11.5 months with a total of 917.3 months of follow-up.

RESULTS

Mean age was 80.0 +/- 8.1 years and predicted operative mortality was 34.5% +/- 20.4% by logistic EuroSCORE and 12.1% +/- 7.7% by The Society of Thoracic Surgeons Risk Calculator. Valves were successfully implanted in all patients. Twelve patients died within 30 days (30-day mortality: 16.9% in all patients, 33% in the first 15 patients, and 12.5% in the remainder), and 10 patients died subsequently. Overall survival at 24 and 36 months was 66.3% +/- 6.4% and 58.0% +/- 9.5%, respectively. Among 59 patients who survived at least 30 days, 24- and 36-month survivals were 79.8% +/- 6.4% and 69.8% +/- 10.9%, respectively. Late valve-related complications were rare. New York Heart Association functional class improved significantly from preoperative 3.3 +/- 0.8 to 1.8 +/- 0.8 at 24 months. The aortic valve area and mean gradient remained stable at 24 months (1.6 +/- 0.3 cm(2) and 10.3 +/- 5.9 mm Hg, respectively).

CONCLUSION

Our outcome suggests that transapical transcatheter aortic valve implantation provides sustained clinical and hemodynamic benefits for up to 36 months in selected high-risk patients with symptomatic severe aortic stenosis.

Determinants of significant paravalvular regurgitation after transcatheter aortic valve: implantation impact of device and annulus discongruence

OBJECTIVES

The aim of this study was to assess prosthesis/annulus discongruence and its impact on the occurrence of significant aortic regurgitation (AR) immediately after transcatheter aortic valve implantation (TAVI).

BACKGROUND

Paravalvular AR might occur after TAVI, but its determinants remain unclear.

METHODS

Comprehensive echocardiographic examinations were performed in 74 patients who underwent TAVI with a balloon expandable device. Congruence between annulus and device was appraised with the cover index: 100 x (prosthesis diameter - transesophageal echocardiography annulus diameter)/prosthesis diameter.

RESULTS

At baseline aortic valve area was 0.67 +/- 0.2 cm(2), and mean gradient was 50 +/- 15 mm Hg. The TAVI used transfemoral approach in 46 patients (62%) and transapical access in 28 (38%). Prosthesis size was 23 mm in 24 patients (34%) and 26 mm in 50 patients (66%). After TAVI, paravalvular AR was absent in 5 patients (7%), graded 1/4 in 53 (72%), 2/4 in 12 (16%), and 3/4 in 4 (5%). Occurrence of AR >or=2/4 was related to greater patient height, larger annulus, and smaller cover index (all p < 0.002) but not to ejection fraction, severity of stenosis, or prosthesis size. AR >or=2/4 was never observed in patients with aortic annulus <22 mm or with a cover index >8%. Significant improvements were observed from the first 20 cases (AR >or=2/4, 40%) to the last 54 (AR >or=2/4, 15%) (p = 0.02). In multivariate analysis, independent predictors of AR >/=2/4 were low cover index (odds ratio: 1.22; per confidence interval: 1.03 to 1.51 per 1% decrease, p = 0.02) and first versus last procedures (odds ratio: 2.24; 95% confidence interval: 1.07 to 5.22, p = 0.03).

CONCLUSIONS

Our study shows that the occurrence of AR >or=2/4 is related to prosthesis/annulus discongruence even after adjustment for experience. Hence, to minimize paravalvular AR, appropriate annular measurements and prosthesis sizing are critical.

Role of echocardiography in percutaneous aortic valve implantation

OBJECTIVES

This study was designed to investigate the usefulness and limitations of echocardiography in optimizing the outcome of percutaneous aortic valve implantation.

BACKGROUND

Percutaneous aortic valve implantation is an emerging technique that has the potential to revolutionize the treatment of aortic valve disease. To date, however, the technique has been limited by technical constraints. Precise positioning of the valve is essential to minimize the potential for paravalvular regurgitation or device migration. Initial experience with device placement utilized fluoroscopic guidance only.

METHODS

Candidates for percutaneous aortic valve implantation were evaluated with transthoracic echocardiography (TTE) to assess aortic annular dimension and aortic valve hemodynamics. Fifty consecutive patients were deemed suitable for percutaneous aortic valve implantation. Seventy-four percent (37 of 50) of patients underwent transesophageal echocardiography (TEE) during the procedure.

RESULTS

Eighty-six percent (43 of 50) of patients had successful implantation, of which 77% (33 of 43) had TEE. Transthoracic echocardiography was used to determine annular dimension and was useful in guiding correct device sizing. Transesophageal echocardiography was able to successfully guide device implantation in 97% (33 of 34) of patients in whom the native valve was crossed with the percutaneous heart valve. Transesophageal echocardiography was used for the early detection of paravalvular aortic regurgitation (AR) and complemented fluoroscopy in the detection of complications. Additional balloon dilatation of the percutaneous heart valve was performed in 12 patients because of significant paravalvular AR, with 7 showing improvement in AR grade. After the procedure, early outcomes were evaluated using TTE. All patients in whom the device was successfully placed (43 of 50) had improvement in their aortic stenosis. Paravalvular AR, although present in many patients, is usually mild and has not emerged as a significant problem.

CONCLUSIONS

Echocardiography has an important role in case selection, in guiding device placement, and in detecting complications of percutaneous aortic valve implantation.

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.

In vivo short-term doppler hemodynamic profiles of 189 carpentier-edwards perimount pericardial bioprosthetic valves in the mitral position

We sought to determine the hemodynamic performance of the Carpentier-Edwards Perimount pericardial valve in the mitral position. We reviewed the Doppler echocardiographic data on 189 patients (110 women; 68 +/- 12 years of age) who were implanted with this valve (7.6 days +/- 13 postoperatively) at our institution between September 2000 and May 2002. The average ejection fraction was 47%. For all valves, the peak velocity was 1.9 +/- 0.3 m/s, peak gradient was 15 +/- 4.8 mm Hg, and mean gradient was 5.8 +/- 2 mm Hg. The pressure half-time was 93 +/- 24 milliseconds, with a calculated effective orifice area of 2.5 +/- 0.6 cm2. The average effective orifice area by continuity equation (83 valves) was 1.5 +/- 0.5 cm2. The mitral regurgitation was graded mild or less in 97.5% of all valves. This is the largest series establishing the favorable hemodynamic behavior of the different sizes of a new Perimount mitral valve, and the reported data could serve as a reference.

Prevalence and clinical significance of incidental paraprosthetic valvar regurgitation: a prospective study using transoesophageal echocardiography

OBJECTIVE

To assess the prevalence, mechanisms, and significance of paraprosthetic regurgitation detected incidentally by transoesophageal echocardiography (TOE) in patients after heart valve replacement.

DESIGN

Prospective observational study.

SETTING

Tertiary referral centre.

PATIENTS

360 consecutive patients (mean (SD) age 65.8(9.5) years, 193 women) undergoing elective first ever valve replacement.

METHODS

Postoperative and follow up TOE, and tests for haemolysis and anaemia.

RESULTS

There were 243 aortic, 90 mitral, and 27 double valve replacements, using 316 mechanical and 44 tissue valves, giving 270 aortic and 117 mitral valves. One patient with severe paraprosthetic mitral regurgitation underwent immediate reoperation and was excluded from subsequent analyses. Paraprosthetic jets were detected around 16 (6%) of the aortic and 38 (32%) of the mitral valves (p < 0.05) at the postoperative study. Follow up TOE was available for 151 aortic and 67 mitral valves, 0.9 (0.5) years after operation. Paraprosthetic jets were present in 15 (10%) of the aortic and 10 (15%) of the mitral valves (NS). Two thirds of the aortic and a fifth of the mitral jets were new. Paraprosthetic jets were more common in aortic valves in a supra-annular (12 of 88, 14%) than in an intra-annular position (4 or 182, 2%; p < 0.005) and in mitral valves inserted with continuous (36 of 88, 41%) rather than interrupted sutures (2 of 28, 7%; p < 0.001). Lactate dehydrogenase concentration was higher in patients with paraprosthetic jets than in those without (752 (236) v 654 (208) IU/l, p < 0.001). Haemoglobin and haptoglobin concentrations were not different.

CONCLUSIONS

Small paraprosthetic leaks are common, are related to surgical factors, are not associated with increased subclinical haemolysis, and are benign during the first year after heart valve replacement.

Unsteady effects on the flow across tilting disk valves

The present study simulates numerically the flow across two-dimensional tilting disk models of mechanical heart valves. The time-dependent Navier-Stokes equations are solved to assess the importance of unsteady effects in the fully open position of the valve. Flow cases with steady or physiological inflow conditions and with fixed or moving valves are solved. The simulations lead into mixed conclusions. It is obvious that steady inflow cases that account for vortex shedding only cannot model realistic physiological cases. In cases with imposed physiological inflow, the details of the flow field for fixed and moving valves might differ in the fully open position as well, although the gross features are quite similar. The fixed valve case consistently results in safe estimations of several critical quantities such as the axial force, the maximal shear stress on the valve, or the transvalvular pressure drop. Thus, fixed valve simulations can provide useful information for the design of prosthetic heart valves, as long as the properties in the fully open position only are sought.

Accuracy and cost- and time-effectiveness of digital clip versus videotape interpretation of echocardiograms in patients with valvular disease

BACKGROUND

Although digital and videotaped images are known to be comparable for the evaluation of left ventricular function, their relative accuracy for assessment of more complex anatomy is unclear. We sought to compare reading time, storage costs, and concordance of video and digital interpretations across multiple observers and sites.

METHODS

One hundred one patients with valvular (90 mitral, 48 aortic, 80 tricuspid) disease were selected prospectively, and studies were stored according to video and standardized digital protocols. The same reviewer interpreted video and digital images independently and at different times with the use of a standard report form to evaluate 40 items (e.g., severity of stenosis or regurgitation, leaflet thickening, and calcification) as normal or mildly, moderately, or severely abnormal. Concordance between modalities was expressed at kappa. Major discordance (difference of >1 level of severity) was ascribed to the modality that gave the lesser severity. CD-ROM was used to store digital data (20:1 lossy compression), and super-VHS videotape was used to store video data. The reading time and storage costs for each modality were compared.

RESULTS

Measured parameters were highly concordant (ejection fraction was 52% +/- 13% by both). Major discordance was rare, and lesser values were reported with digital rather than video interpretation in the categories of aortic and mitral valve thickening (1% to 2%) and severity of mitral regurgitation (2%). Digital reading time was 6.8 +/- 2.4 minutes, 38% shorter than with video (11.0 +/- 3.0, range 8 to 22 minutes, P <.001). Compressed digital studies had an average size of 60 +/- 14 megabytes (range 26 to 96 megabytes). Storage cost for video was A$0.62 per patient (18 studies per tape, total cost A$11.20), compared with A$0.31 per patient for digital storage (8 studies per CD-ROM, total cost A$2.50).

CONCLUSION

Digital and video interpretation were highly concordant; in the few cases of major discordance, the digital scores were lower, perhaps reflecting undersampling. Use of additional views and longer clips may be indicated to minimize discordance with video in patients with complex problems. Digital interpretation offers a significant reduction in reading times and the cost of archiving.

Transesophageal echocardiographic (TEE) evaluation of prosthetic valves

TEE overcomes many of the imaging constraints associated with transthoracic echocardiography for the assessment of valvular anatomy and function. Additional imaging artifacts and constraints associated with prosthetic valves are minimized or overcome with TEE. As such, TEE allows assessment of prosthetic valve anatomy and function and paraprosthetic anatomy, and serves as the diagnostic imaging modality of choice for patients with suspected prosthesis dysfunction or endocarditis.

Comparative evaluation of TEE, conventional MRI and contrast-enhanced 3D breath-hold MRA in the post-operative follow-up of dissecting aneurysms

PURPOSE

To verify the diagnostic potentialities of conventional magnetic resonance imaging (MRI), breath-hold 3D contrast enhanced MR angiography (C3D MRA) and transesophageal echocardiography (TEE) in patients surgically treated for type A aortic dissection.

MATERIALS AND METHODS

Twenty-nine patients (21 males and 8 females), surgically treated for type A aortic dissection, were evaluated with MRI using a 1.5 T (GE Horizon Echospeed 8.2) with standard gated SE sequences and breath-hold 3D fast SPGR after intravenous Gd injection (0.2 mmol/kg). 3D MIP reconstruction was obtained. TEE evaluation was performed with a HP 2000 system and a biplane 5 MHz probe. The sizes of aortic root, distal anastomosis, descending aorta and periprosthetic thickening were measured. Regional false lumen and aortic branch involvement were also evaluated.

RESULTS

Concordance among TEE, conventional MRI and C3D MRA was observed in the evaluation of aortic root (MRI vs. C3D MRA r = 0.93; MRI vs. TEE r = 0.84; C3D MRA vs. TEE r = 0.84) and descending aorta (r = 0.94, 0.91 and 0.92, respectively). The interobserver variability was also very low. Inadequate agreement was observed for distal anastomosis. C3D MRA was inadequate in the evaluation of periprosthetic thickening; r = 0.73 was obtained between MRI and TEE. For qualitative data: TEE was inadequate in the evaluation of the abdominal aorta and branches. C3D MRA depicted supra-aortic vessel involvement in more cases than the other techniques.

CONCLUSION

C3D MRA is a fast and accurate technique in the evaluation of the endoluminal alterations and involvement of the aortic branches. Conventional MRI allows a direct evaluation of the aortic wall and periaortic tissue. TEE is less accurate in the evaluation of aortic branches and abdominal aorta.

Incorrect echocardiographic diagnosis in patients with mechanical prosthetic valve dysfunction: correlation with surgical findings

PURPOSE

To identify the rate of occurrence and type of incorrect echocardiographic diagnoses in patients with mechanical valve prostheses.

PATIENTS AND METHODS

We studied 170 consecutive patients (73 women and 97 men) with a total of 208 prostheses who underwent surgery for mitral (n = 136) or aortic (n = 72) valve dysfunction between January 1991 and December 1997. Preoperative echocardiographic data were compared with surgical findings. Any major discrepancy between the echocardiographic reports and surgery was judged to be unconfirmed when the preoperative echocardiographic diagnosis was not confirmed at surgery, but the prosthesis was found to be dysfunctioning; and was judged to be erroneous when the preoperative echocardiographic diagnosis was not confirmed, and surgical inspection failed to reveal any other prosthetic abnormality.

RESULTS

There were 25 (12%) diagnostic errors. Of the 136 mitral prostheses, there were 9 unconfirmed diagnoses of paravalvular regurgitation (6 had a fibrous tissue overgrowth, 1 had a thrombus with fibrous tissue overgrowth, 1 had endocarditis vegetations, and 1 had a ball variance) and 5 erroneous diagnoses. Eleven diagnostic errors were made in the 72 aortic prostheses: there were 9 unconfirmed diagnoses (paravalvular regurgitation was diagnosed as transvalvular in 7, and transvalvular regurgitation as paravalvular in 2 cases), and 2 erroneous diagnoses.

CONCLUSIONS

Although echocardiography has gained great credibility among clinicians, special care should be taken when assessing patients in whom prosthetic valve dysfunction is suspected.

Natural history of early aortic paraprosthetic regurgitation: a five-year follow-up

OBJECTIVES

To assess the incidence and natural course of paravalvular leaks detected early after aortic valve replacement.

BACKGROUND

Although the use of echocardiography has simplified the postoperative assessment of patients with aortic valve replacement, there are no data regarding the natural history of early detected paravalvular aortic leaks.

METHODS

Eighty-four consecutive patients with aortic valve replacement were prospectively followed clinically every 6 months and by echocardiography early (11 +/- 7 days), at midterm (27 +/- 3 months), and late (63 +/- 4 months) after aortic valve replacement. The competence of artificial valves was assessed by Doppler color flow mapping.

RESULTS

Paraprosthetic leaks were detected in 40 (47.6%) aortic prostheses during the early study; the majority (90%) were small. All leaks remained unchanged during the follow-up period. Left ventricular dimensions and function did not differ between patients with or without paravalvular leak during the follow-up. Left ventricular fractional shortening, however, increased during the intermediate study in both subgroups, indicating improved left ventricular function overall. Three patients had severe paravalvular regurgitation suddenly develop from late infective endocarditis, and 1 patient had a degenerative tissue valve failure 4 years after implantation.

CONCLUSIONS

Paraprosthetic aortic leaks detected early after surgery, in the absence of valve infection, are common, are usually small, and have a benign course. However, the development of new, usually severe, regurgitation should raise the suspicion of prosthetic valve endocarditis or bioprosthetic valve failure.

Simultaneous Doppler and catheter transvalvular pressure gradients across St Jude bileaflet mitral valve prosthesis: in vivo study in a chronic animal model with pediatric valve sizes

A mixture of valve types has been used in previous in vivo studies to assess the accuracy of Doppler echocardiography compared with catheter-measured pressure gradients across prosthetic mitral valves. However, limited data exist regarding the most commonly used bileaflet mechanical valve. We studied 14 sheep with St Jude Medical mechanical mitral valves. Continuous wave Doppler data were obtained across each of the 3 valve orifices. Hemodynamic data were obtained simultaneously by direct measurements with catheters. Valve sizes commonly used in the pediatric population in the mitral position (23 mm, 25 mm, and 27 mm) were studied. Linear regression analyses of Doppler-predicted versus catheter-measured gradients provided correlation coefficients ranging from 0.75 to 0.91. Agreement analysis demonstrated a scatter of Doppler data about the regression line. Although a reasonably good correlation of Doppler-predicted peak and mean pressure gradients across bileaflet mechanical valves exists in the mitral position, caution is needed when this method is applied to patients. Doppler overestimation was greatest across the 23-mm valves. Analyses of the specific orifice interrogated demonstrated higher estimated pressure gradients across the central orifice compared with the side orifices.

Differentiating thrombus from pannus formation in obstructed mechanical prosthetic valves: an evaluation of clinical, transthoracic and transesophageal echocardiographic parameters

OBJECTIVES

We sought to determine the clinical and echocardiographic parameters that differentiate thrombus from pannus formation as the etiology of obstructed mechanical prosthetic valves.

BACKGROUND

Distinction of thrombus from pannus on obstructed prosthetic valves is essential because thrombolytic therapy has emerged as an alternative to reoperation.

METHODS

We analyzed clinical, transthoracic and transesophageal echocardiography (TEE) data in 23 patients presenting with 24 obstructed prosthetic valves and compared the findings to pathology at surgery.

RESULTS

Fourteen valves had thrombus and 10 had pannus formation. Patients with thrombus had a shorter duration from time of valve insertion to malfunction, shorter duration of symptoms, but similar New York Heart Association functional class at the time of operation. Patients with thrombus had a lower rate of adequate anticoagulation (21% vs. 89%; p=0.0028). Pannus formation was more common in the aortic position (70% vs. 21%; p=0.035). Abnormal prosthetic valve motion was detected by TEE in all cases with thrombus formation but in 60% with pannus (p=0.0198). Thrombi were larger than pannuses (total length 2.8+/-2.47 cm vs. 1.17+/-0.43 cm; p=0.038). This was mostly due to extension of thrombi into the left atrium in prosthetic mitral valves. Thrombi appeared as a soft mass on the valve in 92% of cases, whereas 29% of pannuses had a soft echo density (p= 0.007). Ultrasound video intensity ratio, derived as the videointensity of the mass to that of the prosthetic valve, was lower in the thrombus group (0.46+/-0.14 vs. 0.71+/-0.17, p=0.006). A videointensity ratio of <0.70 had a positive predictive value of 87% and a negative predictive value of 89% for thrombus. Duration from onset of symptoms to reoperation of <1 month separated thrombus from pannus formation. The best objective clinical parameter for prediction of thrombus was inadequate anticoagulation, whereas the best TEE parameters were qualitative and quantitative ultrasound intensity of the mass. The presence of either inadequate anticoagulation or a soft mass by TEE improved the predictive power of either parameter alone and was similar to that of ultrasound videointensity ratio.

CONCLUSIONS

Duration of symptoms, anticoagulation status and qualitative and quantitative ultrasound intensity of the mass obstructing a mechanical prosthetic valve can help differentiate pannus formation from thrombus and may therefore be of value in refining the selection of patients for thrombolytic therapy of prosthetic valve obstruction.

Hemodynamic Comparison by Doppler Echocardiography of Valves in the Aortic Position: Value of the Continuity Equation to Assess Prosthetic Dysfunction

In 281 patients, we used Doppler echocardiography to compare the hemodynamic performance of different aortic prosthetic valves at three postoperative stages and investigated the value of the continuity equation in diagnosing aortic prosthetic obstruction. A baseline study was performed in 163 patients, a 5 +/- 2-month follow-up study was performed in 103 patients, and a 15 +/- 5-month follow-up study was performed in 65 patients. From baseline to the second study, left ventricular diastolic diameter, heart rate, and maximum (MG) and mean Doppler-derived gradient (MeG) decreased significantly, and left ventricular shortening fraction, systolic blood pressure, stroke volume, and prosthetic valvular area (PVA) increased significantly. No changes were found between the second and third studies. Thus, noninvasive hemodynamic values at the time of follow-up are reported in 171 patients: 86 with Björk-Shiley Monostrut, 27 with Carbomedics, 11 with Medtronic-Hall, 18 with Hancock modified, and 29 with Toronto valve bioprosthesis. Patients implanted with the Toronto had a larger prosthetic size (Monostrut 23 +/- 2 mm, Carbomedics 23 +/- 3 mm, Medtronic-Hall 23 +/- 2 mm, Hancock 23 +/- 2 mm, Toronto 25 +/- 2 mm, P < 0.01) despite a similar body surface area. MeG and MG were lower (MeG [in mmHg] Monostrut 12 +/- 5, Carbomedics 14 +/- 6, Medtronic-Hall 19 +/- 6, Hancock 11 +/- 4, Toronto 7 +/- 5; P < 0.01 between Toronto and all others), and PVA was greater (Monostrut 2.0 +/- 0.7 cm(2), Carbomedics 1.8 +/- 0.8 cm(2), Medtronic-Hall 1.6 +/- 0.7 cm(2), Hancock 1.7 +/- 0.5 cm(2), Toronto 2.2 +/- 0.9 cm(2); P < 0.01 between Toronto and Carbomedics, Medtronic-Hall, and Hancock), even compared with the same sizes in the other valves. A PVA of 0.9 cm(2) or less and MeG of 28 mmHg or more identified prosthetic obstruction with 100% sensitivity and 99% specificity. Hemodynamics change significantly from the early to the late postoperative state. The Toronto valve stentless porcine bioprostheses performs hemodynamically better than other valves. PVA measurement using the continuity equation may accurately identify prosthetic obstruction.

Hemodynamic performance of small aortic valve bioprostheses: is there a difference?

BACKGROUND

There is the potential for left ventricular outflow obstruction when small aortic valve bioprostheses are employed in normal-sized or large adults. It has been hoped that bovine pericardial valves would improve hemodynamic performance in the smaller tissue valve sizes.

METHODS

To determine in vivo hemodynamic performance of heterograft aortic valve prostheses, we analyzed echocardiographic data from patients receiving 21- or 23-mm Carpentier-Edwards pericardial, Medtronic Intact, and Carpentier-Edwards porcine bioprostheses. In addition, data from 19-mm Carpentier-Edwards pericardial valves were included for comparison of hemodynamic performance between valve sizes. Doppler echocardiography was performed in 151 patients within 2 weeks of operation. Left ventricular outflow gradient was derived from continuous Doppler measurements of flow velocity, and effective orifice area was calculated by the continuity equation.

RESULTS

There were statistically significant differences in hemodynamic performance of different sized prostheses for each valve type (effective orifice area, p < 0.01; valvular gradient, p < 0.03). There were, however, no significant differences in effective orifice area or mean gradient for different valve types within each size category.

CONCLUSIONS

The in vivo hemodynamic performance of these three different aortic valve heterograft bioprostheses is similar. Patient-prosthesis mismatch with heterograft prostheses, as demonstrated by the indexed effective orifice area can be avoided by appropriate sizing and use of annular enlarging techniques when necessary.

Doppler echocardiographic assessment of prosthetic aortic valve area: estimation with the continuity equation compared to the Gorlin formula

Effective orifice area of 3 different designs of prosthetic valves implanted in the aortic position was determined by the continuity equation and the Gorlin formula using Doppler hemodynamic data. The orifice area by the two methods correlated well in the case of tilting disc prostheses (r = 0.75, P = 0.0001, n = 37, SEE = 0.17 cm2) but poorly in the case of bileaflet mechanical valves (r = 0.40, P = 0.17, n = 13) and ball-in-cage prostheses (r = 0.58, P = 0.06, n = 11). Estimation of prosthetic aortic valve area by the Gorlin formula is inappropriate in the latter two types of prostheses because of design-related variable empiric constant.

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.

Diagnosis of intermittent obstruction of mechanical mitral valve prostheses by Doppler echocardiography

In summary, this is a report on 5 various malfunctioning mechanical monocuspid mitral prostheses in which Doppler demonstrated intermittent restriction to the prosthetic disc opening, resulting in intermittent obstruction. In all 5 patients, it was mainly this abnormal Doppler signal that alerted us to the presence of prosthetic valve malfunction. In the 3 asymptomatic patients, the variable and intermittent increased delay in prosthetic valve opening was shown to be an early and sensitive echocardiographic sign of prosthesis malfunction in the absence of any significant increase in pressure gradients.

Does multiplane transesophageal echocardiography improve the assessment of prosthetic valve regurgitation?

Assessment of prosthetic valve regurgitation by echocardiography remains difficult. To study the value of the newly introduced multiplane transesophageal technology for this purpose, prosthetic valve regurgitation was examined in 63 consecutive patients with 35 mitral and 33 aortic prostheses (23 bioprostheses and 45 mechanical prostheses). Transvalvular, paravalvular and, in mechanical valves, normal or pathologic transvalvular regurgitation were identified first with 0 degrees (transverse) and 90 degrees (longitudinal) planes combined with flexion of the echoscope tip and then additionally with multiple intermediary planes by transducer rotation. In a subgroup of 20 patients interobserver variability was evaluated. Both methods showed regurgitation in 56 of 68 valves; one additional case of regurgitation was seen by multiplane imaging only. However, 19 cases of regurgitation were not clearly classifiable by biplane transesophageal echocardiography compared with only three with multiplane transesophageal echocardiography. Grading of severity was concordant by both modalities in 66 and discordant in only two cases. Observers disagreed on severity in two of 20 cases based on biplane imaging but in none based on multiplane imaging; classification of regurgitation differed in six of 20 (biplane) and one of 20 (multiplane), respectively. Multiplane transesophageal imaging improves classification of prosthetic regurgitation but has little effect on severity grading.

Echocardiographic assessment of artificial heart valves: British Society of Echocardiography position paper

Images

Doppler hemodynamic profiles of 82 clinically and echocardiographically normal tricuspid valve prostheses

BACKGROUND

Normal Doppler hemodynamics for tricuspid prostheses have not been well characterized in a large group of patients. Therefore, we analyzed comprehensive Doppler echocardiographic examinations of 82 patients with tricuspid prostheses that were normal by clinical and two-dimensional echocardiographic examinations to establish the normal hemodynamics of various types and sizes of tricuspid prostheses.

METHODS AND RESULTS

The earliest complete postoperative echocardiographic study from each patient was chosen for analysis. Doppler examinations were analyzed on an off-line station from tapes or Doppler strip charts. Early velocity, atrial velocity, end-diastolic velocity, pressure half-time, and mean gradient were obtained by digitizing tricuspid velocity curves. The incidence of "physiological" tricuspid prosthetic regurgitation was noted. Ten Doppler cycles were measured for each patient, and maximal, minimal, and average measurements were recorded. The mean values +/- SD of early velocity, atrial velocity, end-diastolic velocity, mean gradient, and pressure half-time and incidence of mild prosthetic regurgitation were reported for each type of prosthesis, as were highest Doppler measurements for each valve type. Average pressure half-time was significantly lower for St Jude than for heterograft prostheses (P = .04). There were no significant differences between the valve types for mean gradient, early velocity, or incidence of prosthetic regurgitation. Increasing prosthesis size was associated with lower average pressure half-time for heterograft prostheses (P = .024). Average differences (respiratory- and cycle-length-dependent) between maximal and minimal values for 10 cardiac cycles were established for each prosthesis.

CONCLUSIONS

This study establishes normal ranges for Doppler hemodynamics of various tricuspid prostheses and emphasizes the importance of measuring multiple cycles for each tricuspid prosthesis, regardless of cardiac rhythm.

Cross-sectional left ventricular outflow tract velocities before and after aortic valve replacement: a comparative study with two-dimensional Doppler ultrasound

To assess whether aortic valve replacement (AVR) results in changes in the flow velocity distribution in the left ventricular outflow tract (LVOT), 10 patients undergoing AVR for aortic stenosis were studied. By extracting velocity information from color flow maps as digital data, instantaneous cross-sectional velocity profiles were constructed. Velocity profiles obtained 1 to 3 days before AVR were compared with recordings made 3 months later. The LVOT velocity profiles were variably skewed both before and after surgery, and no systematic or uniform changes could be detected after AVR. The highest velocities were most often localized in the region from the center of the outflow tract diameter toward the septum both before and after surgery. At the time of peak flow the ratio of the maximum to the cross-sectional mean velocity was 1.38 +/- 0.13 before and 1.39 +/- 0.08 after AVR (NS), and the ratio of the maximum to the mean velocity time integral was 1.47 +/- 0.10 before and 1.56 +/- 0.10 after (NS). We conclude that AVR in patients with aortic stenosis does not result in a change in LVOT velocity profiles that will influence stroke volume estimates with the Doppler technique.

Doppler-derived pressure differences in normally functioning aortic valve prostheses. Studies in Björk-Shiley monostrut and Biocor porcine prostheses

To determine the normal range of maximum and mean Doppler-derived pressure differences for mechanical and bioprosthetic valves in the aortic position, Doppler echocardiography was performed on 239 stable patients with normally functioning Björk-Shiley monostrut (BSM, n = 185) or Biocor porcine (n = 54) prostheses. The interval from aortic valve replacement to echocardiography was 3-9 days. Maximum and mean pressure differences were significantly greater in 21 mm than in 25 or 27 mm BSM prostheses. The pressure differences in 23 mm BSM valves did not diverge significantly from those in 21, 25 or 27 mm valves. The mean pressure difference did not exceed 30 mm Hg in any type or size of studied prosthesis. No significant differences were found in pressure gradients in comparisons between BSM and Biocor prostheses of corresponding sizes. The calculated velocity ratio for BSM prostheses was not significantly influenced by the valve size. We suggest that the normal range of Doppler-derived maximum and mean pressure differences determined in this study be adopted as reference in evaluations of aortic BSM and Biocor valve prostheses.

Assessing prosthetic heart valve function. Value of Doppler echocardiography and patient/prosthetic valve identity and follow-up card

Doppler echocardiography is being used increasingly in the follow-up of patients with valvular heart prostheses because it provides unique hemodynamic information about flow through prosthetic valves. A baseline checkup about 3 months after implantation is now recommended. We therefore now supply each patient with an identity and follow-up card for each particular prosthesis.

Hemodynamic evaluation by Doppler echocardiography of small (less than or equal to 21 mm) prostheses and bioprostheses in the aortic valve position

To assess resting hemodynamics of an unselected group of patients with prostheses or bioprostheses sized less than or equal to 21 mm implanted into the aortic valve position during a 7-year period, 46 of 50 eligible patients were examined by Doppler echocardiography. The valves were Carpentier-Edwards (CE) supraannular 21 mm (n = 8), Medtronic-Hall (MH) 20 mm (n = 8) and 21 mm (n = 21), and the rest (n = 9) were other valves with only 1 to 3 patients in each group. Gradients, valve areas and dimensionless obstruction indexes (ratio of subvalvular/valvular velocities and velocity time integrals) were compared. By analysis of variance, gradients did not differ significantly between the CE supraannular 21 mm, the MH 20 and 21 mm prostheses (peak/mean 25 +/- 8/14 +/- 5, 31 +/- 13/16 +/- 6 and 25 +/- 10/13 +/- 5 mm Hg; p = not significant). Only 2 patients had a mean gradient greater than 25 mm Hg. The valve area was slightly larger for the MH 21 mm group compared with the CE supraannular 21 mm group (1.34 +/- 0.15 vs 1.16 +/- 0.14 cm2, p less than 0.05). The dimensionless obstruction indexes did not differ (CE supraannular 21 mm 0.36 +/- 0.07/0.40 +/- 0.07 (velocities/velocity time integrals), MH 20 mm 0.40 +/- 0.12/0.47 +/- 0.12, MH 21 mm 0.38 +/- 0.05/0.44 +/- 0.06; p = not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Regurgitant flow in cardiac valve prostheses: diagnostic value of gradient echo nuclear magnetic resonance imaging in reference to transesophageal two-dimensional color Doppler echocardiography

Gradient echo nuclear magnetic resonance (NMR) imaging and transesophageal two-dimensional color Doppler echocardiography are flow-sensitive techniques that have been used in the diagnosis and grading of valvular regurgitation. To define the diagnostic value of gradient echo NMR imaging in the detection of regurgitant flow in cardiac valve prostheses and the differentiation of physiologic leakage flow from pathologic transvalvular or paravalvular leakage flow, 47 patients with 55 valve prostheses were examined. Color Doppler transesophageal echocardiography was used for comparison. Surgical confirmation of findings was obtained in 11 patients with 13 valve prostheses. Gradient echo NMR imaging showed regurgitant flow in 37 of 43 valves with a jet seen on transesophageal echocardiography and it detected physiologic leakage flow in 4 additional valves. There was 96% agreement between the two methods in distinguishing between physiologic and pathologic leakage flow. The methods differed on jet origin of pathologic leakage flow in six prostheses. The degree of regurgitation was graded by both NMR imaging and transesophageal echocardiography, according to the area of the regurgitant jet visualized; gradings were identical for 75% of valve prostheses. Quantification of jet length and area showed a good correlation between the two methods (r = 0.85 and r = 0.91, respectively). Gradient echo NMR imaging is a useful noninvasive technique for the detection, localization and estimation of regurgitant flow in cardiac valve prostheses. However, because transesophageal echocardiography is less time-consuming and less expensive, gradient echo NMR imaging is unlikely to displace transesophageal echocardiography and should be used only in the occasional patient who cannot be adequately imaged by echocardiography.

Doppler sonographic evaluation of mechanical and bioprosthetic mitral valve prostheses during exercise with a rate corrected pressure half time

OBJECTIVE

To compare the effect of exercise on pressure half time in patients with mechanical or bioprosthetic mitral valves. A relative pressure half time (pressure half time as a percentage of RR interval) was used in an attempt to correct for the shortening of the diastolic time interval caused by the increase in heart rate during exercise and thus to uncover the effects of valve design on pressure half time during exercise.

PATIENTS

Twenty clinically stable (New York Heart Association grade I-II) patients with mechanical (n = 12) or bioprosthetic (n = 8) mitral valves (median age 51) years. The median time since valve replacement was 42 months.

METHODS

Continuous wave Doppler echocardiography from the apical view at rest and during moderate supine bicycle exercise (50 W).

RESULTS

During exercise the mean (SD) heart rate increased from 79 (12) to 101 (12) beats per minute (95% confidence interval (95% CI) of difference, 15 to 29/min) and the peak pressure gradient from 11 (5) to 18 (6) mm Hg (95% CI of difference 5 to 9 mm Hg). The pressure half time decreased from 114 (30) to 78 (26) ms (95% CI of difference (30-42 ms). There was no difference between the valve types. The relative pressure half time remained unchanged in patients with mechanical valves during exercise (13 (4) rest and 13 (5)% exercise, respectively) and decreased in patients with bioprostheses (17 (3) and 12 (3)%, respectively (95% CI of difference 2 to 8%, p = 0.025).

CONCLUSIONS

In patients with mechanical mitral valves the decrease in the pressure half time during exercise is probably mostly the result of the shortening of the diastolic time interval with increasing heart rate whereas in patients with bioprosthetic valves an increase in functional valve area may contribute to the shortening of pressure half time during exercise.

The Hatle orifice area formula tested in normal bileaflet mechanical mitral prostheses

The Hatle formula was derived empirically in native mitral stenosis and may not be valid for normal prosthetic valves. Bileaflet mechanical prostheses open fully at low flows and have minimal interindividual variation in orifice area. In these valves effective area and measured manufacturer's area should be similar. We studied 60 patients aged 58 +/- 12 yr at a mean of 5 months after implantation with a CarboMedics prosthesis. There was a coexistent aortic prosthesis in 21. All diastolic measurements were averaged over 5 beats and stroke volume was calculated from the integral of the subaortic velocity trace and the cross-sectional area of the left ventricular outflow tract. For the whole group, area by the Hatle formula was 3.1 +/- 0.7 cm2 and measured area was 2.8 +/- 0.4 cm2. There was no significant correlation between these values (p = 0.329). Pressure half-time was more closely correlated with peak transmitral velocity (p = 0.012), RR interval (p = 0.015), diastolic time interval (p = 0.062) and stroke volume (p = 0.074). We conclude that the Hatle formula should not be applied to normal bileaflet mitral prostheses where pressure half-time reflects nonprosthetic factors more closely than orifice area.

Quantitation of mitral regurgitation by transesophageal echocardiography with Doppler color flow mapping: correlation with cardiac catheterization

Eighty consecutive patients who underwent both left ventriculography and single-plane transesophageal echocardiography with Doppler color flow mapping were studied to compare the two techniques in the assessment of mitral regurgitation. Only the mosaic aspect of the regurgitant jet was included in the measurements. Values for inter- and intraobserver variability for the maximal regurgitant area measurements were 10 +/- 9% and 9 +/- 8%, respectively. The best correlation between angiography and Doppler color flow imaging was obtained with the maximal regurgitant area (r = 0.90). A maximal regurgitant area less than 3 cm2 predicted mild mitral regurgitation with a sensitivity of 96%, specificity of 100% and a predictive accuracy of 98%, whereas a maximal regurgitant area greater than 6 cm2 predicted severe mitral regurgitation with a sensitivity of 91%, a specificity of 100% and a predictive accuracy of 98%. A strong, although inferior, correlation was found for the maximal regurgitant area/left atrial area ratio (r = 0.81). A ratio less than 20% predicted mild mitral regurgitation with 94% accuracy, whereas a ratio greater than 35% predicted severe mitral regurgitation with 85% accuracy. Thus, single-plane transesophageal echocardiography with Doppler color flow mapping is an exquisitely sensitive technique for the diagnosis of mitral regurgitation. Minimal degrees of mitral regurgitation can be detected in approximately 62% of patients in whom no mitral regurgitation is detected by angiography. The mosaic maximal regurgitant area is a simple and easily obtainable Doppler echocardiographic index that provides an accurate estimation of mitral regurgitation severity.

Single-plane transesophageal echocardiography for assessing function of mechanical or bioprosthetic valves in the aortic valve position

To assess the value and limitations of single-plane transesophageal echocardiography in the evaluation of prosthetic aortic valve function, 89 patients (69 mechanical and 20 bioprosthetic aortic valves) were studied by combined transthoracic and transesophageal 2-dimensional and color flow Doppler echocardiography. In the assessment of aortic regurgitation, the transthoracic and transesophageal echocardiographic findings were concordant in 71 of 89 patients (80%). In 8 patients, the degree of aortic regurgitation was underestimated by the transthoracic approach; in each case the quality of the transthoracic echocardiogram was poor. In 10 patients, transesophageal echocardiography failed to detect trivial aortic regurgitation due to acoustic shadowing of the left ventricular outflow tract from a mechanical valve in the mitral valve position. Transesophageal echocardiography was superior to transthoracic echocardiography in diagnosing perivalvular abscess, subaortic perforation, valvular dehiscence, torn or thickened bioprosthetic aortic valve cusps, and in clearly distinguishing perivalvular from valvular aortic regurgitation. Transesophageal echocardiography correctly diagnosed bioprosthetic valve obstruction in 1 patient, but failed to diagnose mechanical valve obstruction in another. In conclusion, transesophageal echocardiography offers no advantage over the transthoracic approach in the detection and quantification of prosthetic aortic regurgitation unless the transthoracic image quality is poor. Transesophageal echocardiography is limited in detecting mechanical valve obstruction and in detecting aortic regurgitation in the presence of a mechanical prosthesis in the mitral valve position. However, it is superior to transthoracic echocardiography in identifying perivalvular pathology, differentiating perivalvular from valvular regurgitation and in defining the anatomic abnormality responsible for the prosthetic valve dysfunction. Combined transthoracic and transesophageal examination provides complete anatomic and hemodynamic assessment of prosthetic aortic valve function.

Value of acceleration flow signals proximal to the leaking orifice in assessing the severity of prosthetic mitral valve regurgitation

To test the value of acceleration flow signals proximal to the leaking orifice in assessing the severity of prosthetic mitral valve regurgitation, 39 consecutive patients undergoing left ventriculography were examined by Doppler color flow imaging. Acceleration flow signals proximal to the regurgitant orifice were detected in 27 of the 31 patients who had prosthetic mitral regurgitation by left ventriculography (sensitivity 87%). All four patients without acceleration flow signals had mild prosthetic mitral regurgitation by angiography. No acceleration flow signals were detected in any patient without prosthetic regurgitation by left ventriculography (specificity 100%). Individual values of the maximal area of acceleration flow signals obtained from three orthogonal planes in seven patients with mild prosthetic mitral regurgitation by angiography ranged from 0 to 17 mm2 (mean 4 +/- 6). In 8 patients with moderate prosthetic mitral regurgitation by angiography, the maximal area of acceleration flow signals ranged from 21 to 58 mm2 (mean 33 +/- 15), whereas the maximal area of acceleration flow signals in 16 patients with severe prosthetic regurgitation ranged from 20 to 173 mm2 (mean 102 +/- 41). The maximal area of the acceleration flow signals from three planes correlated well with the angiographic grade of prosthetic mitral regurgitation. There was a significant difference in the maximal area of acceleration flow signals between mild and moderate (p less than 0.001), moderate and severe (p less than 0.001) and mild and severe (p less than 0.001) prosthetic mitral regurgitation. Thus, measurement of acceleration flow signals by Doppler color flow imaging is useful in assessing the severity of prosthetic mitral regurgitation.

Color Doppler regurgitant characteristics of normal mechanical mitral valve prostheses in vitro

BACKGROUND

To evaluate normal regurgitant characteristics of St. Jude (SJ) and Medtronic-Hall (MH) mitral valves, four sizes (25-31 mm) of each were studied in a pulsatile flow model.

METHODS AND RESULTS

Regurgitant flow was measured by flowmeter at left ventricular pressures of 80, 130, and 180 mm Hg. Peak regurgitant flow rates ranged from 6.2 to 12.7 cm3/sec in SJ valves and from 7.9 to 17.5 cm3/sec in MH valves. Regurgitant orifice areas calculated from the Doppler continuity equation ranged from 1.6 to 2.0 mm2 in SJ valves and from 2.2 to 2.9 mm2 in MH valves. Regurgitant volumes across the closed valve at a left ventricular pressure of 130 mm Hg were normalized to an ejection time of 280 msec and ranged from 1.5 to 1.9 cm3 in SJ valves and from 2.1 to 2.8 cm3 in MH valves. Jets were imaged by color Doppler in six rotational planes, and jet size and morphology were compared with those of regurgitant jets from circular orifices with sizes comparable to the calculated prosthetic valve regurgitant orifices (1.1-3.1 mm2). SJ valves showed two converging jets from the pivot points, one central jet, and a variable number of peripheral jets. The mean color jet area derived from the six image planes ranged from 1.6 to 5.3 cm2. Aliasing occurred only close to the valve (maximal distance 0.5-2.0 cm). MH valves showed a large central jet with a maximal length of aliased flow between 2.0 and 5.5 cm. Depending on valve size, driving pressure, and image plane, one or two small peripheral jets were found. These jets did not show aliasing in any case. The mean color jet area ranged from 5.1 to 11.0 cm2. Jets originating from circular orifices of comparable size showed jet areas from 5.5 to 13.9 cm2 and aliasing distances from 3.3 to 7.3 cm. At similar regurgitant orifice areas, driving pressures, and regurgitant flows, the measured color areas and aliasing distances were smallest in SJ valves, larger in MH valves, and largest in simple circular orifices.

CONCLUSIONS

Large, complex regurgitant jets can be found in normal closed SJ and MH valves by color Doppler, although regurgitant flow volume is minimal. Jet size and velocity distribution differs markedly between SJ valves, MH valves, and circular orifices, even with comparable driving pressure, regurgitant orifice area, and regurgitant volume. The characteristic patterns of normal regurgitation must be recognized to avoid incorrect diagnoses of pathological regurgitation in SJ and MH prosthetic valves. MH valves should not be removed solely on the basis of a central regurgitant jet with a long aliasing distance. Peripheral jets in MH valves and all jets in SJ valves should be considered normal as long as no or only minimal aliasing is present. In contrast, peripheral jets with significant aliasing may represent strong evidence of pathological regurgitation.

Patterns of normal transvalvular regurgitation in mechanical valve prostheses

The magnitude and spatial distribution of normal leakage through mechanical prosthetic valves were studied in an in vitro model of mitral regurgitation. The effective regurgitant orifice was calculated from regurgitant rate at different transvalvular pressure differences and flow velocities. This effective orifice area was 0.6 to 2 mm2 for three tilting disc prostheses (Medtronic-Hall sizes 21, 25 and 29) and 0.2 to 1.1 mm2 for three bileaflet valves (St. Jude Medical sizes 21, 25 and 33). In the single disc valves, Doppler color flow examination disclosed a prominent central regurgitant jet around the central hole for the strut, accompanied by minor leakage along the rim of the disc (central to peripheral jet area ratio 3.3 +/- 1.2). The bileaflet prostheses showed a peculiar complex pattern: in planes parallel to the two disc axes, convergent peripherally arising jets were visualized, whereas in orthogonal planes several diverging jets were seen. Mounting the disc and bileaflet valves on a water-filled tube allowed reproduction and interpretation of this pattern: for the bileaflet valve, the jets originated predominantly from valve ring protrusions that contained the axis hinge points and created a converging V pattern in planes parallel to the leaflets and a diverging V pattern in orthogonal planes. Similar patterns were observed during transesophageal echocardiography in 20 patients with a normally functioning St. Jude prosthesis. In 10 patients with a Medtronic-Hall valve, a dominant central jet was observed with one or more smaller peripheral jets. The median central to peripheral jet area ratio was 5 to 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of mitral regurgitation by Doppler echocardiography

The diagnosis and assessment of mitral regurgitation has been one of the main challenges for cardiac ultrasound. Imaging techniques (M-mode and two-dimensional echocardiography) provide direct morphologic and etiologic information of the evaluation of patients with suspected mitral regurgitation. The advent of cardiac Doppler increased tremendously the ability to evaluate mitral regurgitation noninvasively. Continuous-wave and pulsed Doppler have been found to be sensitive and specific in the detection of mitral regurgitation. The introduction of color flow Doppler simplified enormously the assessment of patients with suspected mitral regurgitation. The maximal regurgitant area and maximal regurgitant area corrected for left atrial size have become the most commonly used parameters to evaluate mitral regurgitation by color flow Doppler in the clinical setting. However, the color regurgitant jet area is highly dependent on anatomical, hemodynamic, and equipment factors. A new method, based on the proximal isovelocity surface area, is being evaluated and appears to be relatively independent of equipment factors. Transesophageal echocardiography has been shown to be exquisitely sensitive in the detection of mitral regurgitation. Quantitation of mitral regurgitation by transesophageal echocardiography is currently based on the maximal regurgitant area and this parameter appears to correlate closely with the angiographic degree of mitral regurgitation. Pulmonary venous flow analysis had been used in conjunction with color flow mapping for the evaluation of mitral regurgitation by transesophageal echocardiography. The presence of reversed systolic flow has been shown to be sensitive and specific for the diagnosis of severe mitral regurgitation. Patients with clinically difficult surface studies, flail mitral valve leaflets, and prosthetic mitral valve are best evaluated by the transesophageal approach with interrogation of pulmonary venous flow.