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

Doppler haemodynamics and effective orifice areas of Edwards SAPIEN and CoreValve transcatheter aortic valves

AIMS

Transcatheter aortic valve implantation (TAVI) is a new therapy for severe aortic stenosis in high-risk patients. So far, no reference values for the echocardiographic assessment of this new class of heart valves have been established. The aim of our study was to determine Doppler haemodynamics and the effective orifice area (EOA).

METHODS AND RESULTS

We retrospectively analysed the earliest transthoracic echocardiographic examinations of 146 stable patients after successful TAVI (median 8±20 days). Doppler examinations were analysed for peak instantaneous velocity, peak, and the mean systolic gradient. EOA was determined using the continuity equation. Patients with severe paravalvular aortic or mitral valve regurgitation were excluded. The overall peak instantaneous velocity (n=146) was 2.0±0.4 m/s with a peak systolic gradient of 17.1±7.4 mmHg and a mean gradient of 9.3±4.5 mmHg. The mean EOA was 1.82±0.43 cm2 with an indexed EOA of 1.0±0.27 cm2/m2. In general, all prostheses showed similar values-with the exception of the Edwards Sapien 23 mm which was associated with higher velocities and peak pressure gradients.

CONCLUSION

Our study establishes the normal range for Doppler haemodynamics of four transcatheter aortic valve prostheses. Compared with previously published data of surgically implanted bioprostheses percutaneous valves tend to have similar EOA values but lower mean peak velocities and pressure gradients. In comparison with physiological haemodynamics; however, this new class of heart valves is still associated with a mild obstruction.

Diagnostic evaluation of left-sided prosthetic heart valve dysfunction

Prosthetic heart valve (PHV) dysfunction is a rare, but potentially life-threatening, complication. In clinical practice, PHV dysfunction poses a diagnostic dilemma. Echocardiography and fluoroscopy are the imaging techniques of choice and are routinely used in daily practice. However, these techniques sometimes fail to determine the specific cause of PHV dysfunction, which is crucial to the selection of the appropriate treatment strategy. Multidetector-row CT (MDCT) can be of additional value in diagnosing the specific cause of PHV dysfunction and provides valuable complimentary information for surgical planning in case of reoperation. Cardiac magnetic resonance imaging (CMR) has limited value in the evaluation of biological PHV dysfunction. In this Review, we discuss the use of established imaging modalities for the detection of left-sided mechanical and biological PHV dysfunction and discuss the complementary role of MDCT in this context.

Hemodynamic performance of cryopreserved aortic homograft valves during midterm follow-up

OBJECTIVES

The aim of this prospective study of adult patients operated with a cryopreserved aortic homograft was to use serial echocardiographic data to evaluate the postoperative hemodynamic performance of these valves.

BACKGROUND

Only limited data on hemodynamic performance of aortic homografts at rest and during exercise are available. Controversy also exists regarding incidence and progression of aortic regurgitation (AR).

METHODS

Fifty-nine patients aged 39-86 years who received an aortic homograft (median size 21 mm) implanted with subcoronary technique were studied with serial Doppler-echocardiography (D-E). In 31 of these patients, D-E also was performed during supine exercise.

RESULTS

Overall survival was 100% during a median follow-up of 28 months (range 4-54). During follow-up AR grade II or more was detected in 25% of the patients with an increasing time-related risk of developing AR. Maximum and mean pressure differences at 7 months follow-up calculated with the short form of the Bernoulli equation were 11.4 (4.6) and 5.5 (2.1) mm Hg, respectively. During supine exercise that increased cardiac output 72%, maximum pressure difference increased from 11.9 (5.2) to 18.5 (9.5) mm Hg.

CONCLUSIONS

The aortic homograft valve shows low pressure differences at rest and during exercise, but AR grade I or II is often seen during follow-up. As AR progresses with time we stress the importance of echocardiographic follow-up of patients with aortic homografts.

Long-term Doppler echocardiographic results of aortic or mitral valve replacement with Biocor porcine bioprosthesis

OBJECTIVES

Our objectives were to evaluate the long-term bioprosthetic and cardiac functional outcome after insertion (over a 10-year period) of a new-generation porcine zero pressure-fixed Biocor bioprosthesis, as well as to determine the echocardiographic accuracy for selection of patients requiring reoperation. The long-term systematic Doppler echocardiographic assessment after valve replacement with this bioprosthesis is lacking.

METHODS

Between January 1983 and January 1993, we inserted 756 Biocor prostheses in the aortic (619) or mitral (137) positions. All 51 patients who had a reoperation during the follow-up time were evaluated echocardiographically before reoperation. Additionally, 263 of 446 patients (59%) with aortic bioprostheses and 42 of 74 patients (57%) with mitral bioprostheses who were alive in January 1993 had long-term echocardiographic follow-up.

RESULTS

Group A: Normally functioning bioprostheses were found in the aortic position in 242 of 263 patients and in the mitral position in 33 of 42 patients. Group B: Thirty patients had abnormal bioprosthetic function. Eleven patients had regurgitation, 3 had a combined lesion, and signs of calcification appeared in 16 patients with aortic valves, all with a peak gradient of above 60 mm Hg. Group C: Patients who had a reoperation (41 aortic and 10 mitral) within the follow-up period were followed up echocardiographically from the detection of a possible valve dysfunction until reoperation, and the findings accorded well with those at operation in 49 of 51 patients.

CONCLUSIONS

These findings suggest that, during a long-term follow-up, most bioprostheses function normally, facilitating improved heart function. Abnormalities in a bioprosthesis usually develop gradually, enabling their detection by Doppler echocardiographic evaluations performed regularly or in case of any symptomatic deterioration.

Reference Doppler echocardiographic values for St. Jude Medical, Omnicarbon, and Biocor prosthetic valves in the aortic position

The objectives of the present investigation were (1) to describe Doppler echocardiographic findings for mechanical and biologic aortic valves at an early stage after operation and later in a stable phase and (2) to study the changes occurring between these investigations. Patients (n = 213) who received a mechanical (St. Jude Medical, Omnicarbon) or a biologic (Biocor) valve were studied by Doppler echocardiography within the first week (baseline, n = 203) and after 2 years (late, n = 172). The comparison of baseline with late investigation (mean +/- SD) showed an increase in systolic blood pressure (137 +/- 18.5 to 154 +/- 20.6 mm Hg, p = 0.0001, n = 112), reduction of heart rate (85 +/- 15.3 to 74 +/- 12.0 beats/min, p = 0.0001, n = 141) and increase in stroke volume (59 +/- 20.6 to 77 +/- 19.8 ml, p = 0.0001, n = 132). Prosthetic Doppler echocardiographic findings demonstrated a reduction in blood flow velocity in the left ventricular outflow tract (VLVOT, 1.10 +/- 0.25 to 0.96 +/- 0.23 m/sec, p = 0.0001, n = 146) reduction in peak velocity (Vmax 2.72 +/- 0.53 to 2.59 +/- 0.54 m/sec, p = 0.02, n = 150), reduction in mean pressure gradient (deltaPmean, 18.4 +/- 7.2 to 16.3 +/- 7.3 mm Hg, p = 0.004) and an increase in velocity index (Vmax/VLVOT, 2.56 +/- 0.62 to 2.67 +/- 0.60, p = 0.003, n = 144). The standard deviations of difference between baseline and late investigation expressed as percentage of mean were 25% for VLVOT, 20% for Vmax, 44% for deltaPmean, and 25% for velocity index. In conclusion, this large reference base provides data that should be useful for the clinician evaluating patients with prosthetic valves early after valve replacement as well as at a later stage. When valve dysfunction is suspected a previous investigation for comparison is helpful, and our data describe the changes that normally may be seen between an early baseline and a late investigation.