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

Real time three-dimensional transesophageal echocardiography: a novel approach for the assessment of prosthetic heart valves

OBJECTIVES

To explore our initial experience with real time three-dimensional transesophageal echocardiography (RT3DTEE) for the assessment of prosthetic valves (PV).

METHODS

The study included 40 patients (mean age 35 ± 8.5 years, 68% male) who underwent PV implant. Fifty PV (34 bioprosthetic and 16 mechanical) were evaluated using two-dimensional (2D)TEE and RT3DTEE to rule out PV dysfunction.

RESULTS

In all patients, RT3DTEE allowed good and simultaneous visualization of PV leaflets. Ten patients had normal functioning PV (5 in mitral, 3 in aortic, and 2 in tricuspid positions). Infective endocarditis was evident in 13 patients (20 PV) by repeated 2DTEE. RT3DTEE confirmed the 2DTEE diagnosis of endocarditis in same patients. Clear delineation of vegetations (size, site, and number) was obtained from RT3DTEE full volume while the vegetation attachment, consistency, mobility and its relation to valve structure were obtained using zoom 3D. Paraaortic abscesses size, site, extension, wall thickness of the abscess could be identified by RT3DTEE in 7 PV. Through cropping of the full-volume 3D images, the orifice of communication between the abscess cavity and aorta could be visualized well in en face view. Color full-volume allowed the detection of paravalvular regurgitation (size, location, direction, and extent) in 8 patients. In the 18 PV who underwent redo surgery, the intra-operative findings confirmed the RT3DTEE description of PV lesions.

CONCLUSION

Real time 3DTEE improved the anatomical and functional assessment of PV with better understanding of the underlying causes of PV dysfunction; hence, it could improve the management planning for such patients.

Redo surgery risk in patients with cardiac prosthetic valve dysfunction

INTRODUCTION

The aim of the study was to analyse the risk factors of early and late mortality in patients undergoing the first reoperation for prosthetic valve dysfunction.

MATERIAL AND METHODS

A retrospective observational study was performed in 194 consecutive patients (M = 75, F = 119; mean age 53.2 ±11 years) with a mechanical prosthetic valve (n = 103 cases; 53%) or bioprosthesis (91; 47%). Univariate and multivariate Cox statistical analysis was performed to determine risk factors of early and late mortality.

RESULTS

The overall early mortality was 18.6%: 31.4% in patients with symptoms of NYHA functional class III-IV and 3.4% in pts in NYHA class I-II. Multivariate analysis identified symptoms of NYHA class III-IV and endocarditis as independent predictors of early mortality. The overall late mortality (> 30 days) was 8.2% (0.62% year/patient). Multivariate analysis identified age at the time of reoperation as a strong independent predictor of late mortality.

CONCLUSIONS

Reoperation in patients with prosthetic valves, performed urgently, especially in patients with symptoms of NYHA class III-IV or in the case of endocarditis, bears a high mortality rate. Risk of planned reoperation, mostly in patients with symptoms of NYHA class I-II, does not differ from the risk of the first operation.

Evaluation of 17-mm St. Jude Medical Regent prosthetic aortic heart valves by rest and dobutamine stress echocardiography

BACKGROUND

The prosthesis used for aortic valve replacement in patients with small aortic root can be too small in relation to body size, thus showing high transvalvular gradients at rest and/or under stress conditions. This study was carried out to evaluate rest and Dobutamine stress echocardiography (DSE) hemodynamic response of 17-mm St. Jude Medical Regent (SJMR-17 mm) in relatively aged patients at mean 24 months follow-up.

METHODS AND RESULTS

The study population consisted of 19 patients (2 men, 17 women, mean age 69.2 +/- 7.3 years). All patients underwent rest Doppler echocardiography before and after surgery and basal and DSE at follow up (infused at rate of 5 microg/Kg/min and increased by 5 microg/Kg/min at 5 min intervals up to 40 microg/Kg/min). The following parameters were evaluated at rest and/or under DSE: heart rate (HR), ejection fraction (EF), cardiac output (CO), peak and mean velocity and pressure gradients (MxV, MnV, MxPG, MnPG), effective orifice area (EOA), indexed EOA (EOAi), left ventricular mass (LVM), indexed LVM (LVMi), Velocity Time Integral at left ventricular outflow tract (VTI LVOT) and transvalvular (Aortic VTI), Doppler velocity index (DVI). At rest MxPG and MnPG were 29.2 +/- 7.1 and 16.6 +/- 5.8 mmHg, respectively; EOA and EOAi resulted 1.14 +/- 0.3 cm(2) and 0.76 +/- 0.2 cm(2)/m(2); DVI was normal (0.50 +/- 0.1). At follow-up LVM and LVMi decreased significantly from pre-operative value of 258 +/- 43 g and 157.4 +/- 27.7 g/m(2) to 191 +/- 23.8 g and 114.5 +/- 10.6 g/m(2), respectively. DSE increased significantly HR, CO, EF, MxGP (up to 83.4 +/- 2 1.9 mmHg), MnPG (up to 43.2 +/- 12.7 mmHg). EOA, EOAi, DVI increased insignificantly (from baseline up to 1.2 +/- 0.4 cm(2), 0.75 +/- 0.3 cm(2)/m(2) and 0.48 +/- 0.1 respectively). Two patients developed significant intraventricular gradients.

CONCLUSION

These data show that SJMR 17-mm prostheses can be safely implanted in aortic position in relatively aged patients, offering a satisfactory hemodynamic performance at rest and under DSE, with full utilization of its available orifice, suggesting that a possible mild prosthesis-patient mismatch is not an issue of clinical relevance when this small prosthesis is used. Rest and Dobutamine stress echocardiography is a useful and effective means for evaluating prosthesis hemodynamics and for monitoring the expected LVH regression.

Does the type of prosthesis influence early left ventricular mass regression after aortic valve replacement? Assessment with magnetic resonance imaging

BACKGROUND

Debate exists regarding selection of the prosthesis type most likely to maximize early left ventricular (LV) mass regression after aortic valve replacement (AVR) for stenotic valvular disease. The aim of this study was to compare the degree of LV mass regression measured by MRI 6 months after prospectively randomized valve implantation for two biological prostheses, stented and stentless, and for two mechanical valves, tilting disc and bileaflet.

METHODS

Thirty-nine consecutive patients with predominant aortic stenosis accepted for elective AVR were studied. Twenty patients requiring a tissue prosthesis were randomly assigned to receive either a Freestyle or Mosaic valve. The remaining 19 patients in whom mechanical prosthesis was indicated were randomly assigned to receive either an Ultracor or an ATS valve.

RESULTS

There was no difference in valve size implanted between the compared groups. LV mass measurements were performed with MRI (1.5-T Vision, Siemens, Germany) immediately before and 6 months after surgery. All valve types produced significant postoperative reduction in LV mass compared with preoperative values (P <.01). Percent change in LV mass regression was similar between the two porcine valve types, Mosaic (24.4% +/- 11.1%) and Freestyle (21.1% +/- 16.7%), and between the two mechanical valve designs, Ultracor (19.3% +/- 9.5%) and ATS (26.3% +/- 10.8%), respectively.

CONCLUSIONS

Significant LV remodeling occurs early after AVR for aortic stenosis. The degree of regression in LV mass is independent of prosthesis type implanted.

Intraoperative transesophageal echocardiographic assessment of acute prosthetic aortic valve regurgitation after mitral valve replacement: value of the deep transgastric long-axis view

The transesophageal echocardiographic assessment of prosthetic aortic valve function is made more difficult by the presence of a mechanical mitral valve prosthesis because echocardiographic views conventionally used to assess the aortic valve function are obscured by acoustic shadowing and artifacts. We report the use of intraoperative transesophageal echocardiography in a patient who developed severe prosthetic aortic valve regurgitation after implantation of a mechanical mitral valve, in whom conventional multiplane midesophageal views failed to reveal aortic regurgitation owing to acoustic shadowing and artifacts from the prosthetic mitral valve. We report the value of the deep transgastric long-axis view of the aortic valve that provided an unobstructed view of the left-ventricular outflow tract, and clearly demonstrated severe aortic regurgitation as a result of interference with the prosthetic aortic valve mechanism by the implanted mitral valve prosthesis. This case also emphasizes the importance of a comprehensive intraoperative transesophageal examination, including that of surrounding structures, to detect iatrogenic complications during mitral valve replacement.

Effect of mechanical aortic valve orientation on coronary artery flow: comparison of tilting disc versus bileaflet prostheses in pigs

OBJECTIVE

Orientation for optimal systolic performance of tilting disc and bileaflet aortic valves was defined in previous studies. The present study investigates the influence of valve orientation on coronary artery flow in an animal model.

METHODS

A rotation device holding either a Medtronic Hall tilting disc (n = 4; Medtronic, Inc, Minneapolis, Minn), a St Jude Medical bileaflet (n = 4; St Jude Medical, Inc, St Paul, Minn), or a Medtronic Advantage bileaflet (n = 3) aortic valve was implanted. The device allowed rotation of the valve without reopening the aorta. Flow through the left anterior descending coronary artery was measured preoperatively and at normal versus high cardiac output after weaning from extracorporeal circulation. Measurements were performed at the best and worst hemodynamic position, as defined previously.

RESULTS

Coronary flow rates were similar in all animals preoperatively (26 +/- 4.1 mL/min). After aortic valve replacement, left anterior descending flow increased significantly to 58.2 +/- 10.6 mL/min. Highest flow rates at normal cardiac output were found in the optimum orientation, especially for the Medtronic valves (Medtronic Hall, 64 +/- 8.7 mL/min; Medtronic Advantage, 64.6 +/- 11.6 mL/min; St Jude Medical, 48.3 +/- 10.3 mL/min), whereas the worst position demonstrated significantly lower left anterior descending flow, with no differences among valves (Medtronic Hall, 37.5 +/- 1.3 mL/min; St Jude Medical, 35.7 +/- 10.7 mL/min; Medtronic Advantage, 39.8 +/- 10 mL/min). Left anterior descending artery flow increased significantly with higher cardiac output.

CONCLUSIONS

Coronary blood flow was significantly influenced by mechanical aortic valve implantation and the orientation of prostheses. For both valve designs, the previously defined optimum orientation with respect to pressure gradients and turbulence demonstrated the highest left anterior descending flow rates. Even in its optimum orientation, the St Jude Medical valve showed significantly lower coronary flow than the other valves.

[A comparative study of the follow-up and hemodynamics in vivo of 21 mm Carpentier-Edwards supra-annular and perimount bioprostheses]

INTRODUCTION AND OBJECTIVES

Analysis and comparison of the clinical performance and hemodynamics in vivo of 21 mm Carpentier-Edwards supra-annular (CESA) and Perimount (CEPM) aortic bioprostheses.

METHODS

A follow-up study was made of 40 patients implanted a 21 mm CESA (n = 21) or CEPM (n = 19) prosthesis between October 1992 and September 1997. All eligible survivors (14 CESA, 12 CEPM) were assessed echocardiographically.

RESULTS

There were no significant differences between models in the effective orifice area (1.6 cm2 for CESA, 1.44 cm2 for CEPM), peak flow rate (rest: 2.5 m/s for CESA, 2.3 m/s for CEPM; post-dobutamine: 3.4 m/s for CESA, 3.3 m/s for CEPM), mean flow rate (rest: 1.7 m/s for CESA, 1.6 m/s for CEPM; post-dobutamine: 2.5 m/s for CESA, 2.2 m/s for CEPM), peak gradient (rest: 28.3 mmHg for CESA, 21.6 mmHg for CEPM; post-dobutamine: 48.4 mmHg for CESA, 41.6 mmHg for CEPM), and mean gradient (rest: 15.8 mmHg for CESA, 12.0 mmHg for CEPM; post-dobutamine: 28.5 mmHg for CESA, 22.5 mmHg for CEPM).

CONCLUSION

In our experience, these two prosthetic models have similar hemodynamic characteristics in small aortic annuli.

Long Term Clinical and Echocardiographic Results of Isolated Aortic Valve Replacement in Elderly Patients

Results after isolated aortic valve replacement with bileaflet prostheses in patients over 70 years old were reviewed.

One-hundred-twenty-eight elderly patients were operated on between January 1988 and January 2000. Patients with associated heart disease were excluded from the study. Preoperative data, early and late postoperative mortality, all valve related complications and data concerning anticoagulation status were recorded.

Hospital mortality was 9.3%. Mean follow-up time was 60.98±2.23 months. Twelve-year actuarial survival was 69.6±0.08%. Valve related and anticoagulation related complication rates (0.8% and 1.6% respectively) and actuarial freedom (99±0.009 both) were low, as well as the mean interval between consecutive INR checks (18.39±1.90 days) and the mean INR value (2.17±0.135). Late echocardiographic results showed low postoperative mean transprosthetic gradients (15.48±0.94).

Bileaftlet prostheses in the elderly can achieve excellent results with a low incidence of anticoagulation related complications and low risk of reoperation. Older age can no longer be considered a contraindication to bileaftlet prosthesis implant.

Assessment of effective orifice area of prosthetic aortic valves with Doppler echocardiography: an in vivo and in vitro study

OBJECTIVES

We sought to evaluate the Doppler assessment of effective orifice area in aortic prosthetic valves. The effective orifice area is a less flow-dependent parameter than Doppler gradients that is used to assess prosthetic valve function. However, in vivo reference values show a pronounced spread of effective orifice area and smaller orifices than expected compared with the geometric area.

METHODS

Using Doppler echocardiography, we studied patients who received a bileaflet St Jude Medical valve (n = 75; St Jude Medical, Inc, St Paul, Minn) or a tilting disc Omnicarbon valve (n = 46; MedicalCV, Incorporated, Inver Grove Heights, Minn). The prosthetic valves were also investigated in vitro in a steady-flow model with Doppler and catheter measurements in the different orifices. The effective orifice area was calculated according to the continuity equation.

RESULTS

In vivo, there was a wide distribution with the coefficient of variation (SD/mean x 100%) for different valve sizes ranging from 21% to 39% in the St Jude Medical valve and from 25% to 33% in the Omnicarbon valve. The differences between geometric orifice area and effective orifice area in vitro were 1.26 +/- 0.41 cm(2) for St Jude Medical and 1.17 +/- 0.38 cm(2) for Omnicarbon valves. The overall effective orifice areas and peak catheter gradients were similar: 1.35 +/- 0.37 cm(2) and 25.9 +/- 16.1 mm Hg for St Jude Medical and 1.46 +/- 0.49 cm(2) and 24.6 +/- 17.7 mm Hg for Omnicarbon. However, in St Jude Medical valves, more pressure was recovered downstream, 11.6 +/- 6.3 mm Hg versus 3.4 +/- 1.6 mm Hg in Omnicarbon valves (P =.0001).

CONCLUSIONS

In the patients, we found a pronounced spread of effective orifice areas, which can be explained by measurement errors or true biologic variations. The in vitro effective orifice area was small compared with the geometric orifice area, and we suspect that nonuniformity in the spatial velocity profile causes underestimation. The St Jude Medical and Omnicarbon valves showed similar peak catheter gradients and effective orifice areas in vitro, but more pressure was recovered in the St Jude Medical valve. The effective orifice area can therefore be misleading in the assessment of prosthetic valve performance when bileaflet and tilting disc valves are compared.

Hemodynamic performance of the 21-mm Sorin Bicarbon mechanical aortic prostheses using dobutamine Doppler echocardiography

BACKGROUND

Small-sized mechanical aortic prostheses are commonly associated with generation of high transvalvular gradients, particularly in patients with large body surface area, and can result in patient-prosthesis mismatch. This study evaluates the hemodynamic performance of 21-mm Sorin Bicarbon bileaflet mechanical prostheses using dobutamine stress echocardiography.

METHODS

Fourteen patients (7 women; mean age, 63+/-8 years) who had undergone aortic valve replacement with a 21-mm Sorin Bicarbon bileaflet mechanical prosthesis 32.4+/-5.1 months previously were studied. After a resting Doppler echocardiogram, a dobutamine infusion was started at a rate of 5 microg x kg(-1) x min(-1) and increased to 30 microg x kg(-1) x min(-1) at 15-minute intervals. Pulsed- and continuous-wave Doppler echocardiographic studies were performed at rest and at the end of each increment of dobutamine. Both peak and mean velocity and pressure gradient across the prostheses were measured, and effective orifice area, discharge coefficient, and performance index were calculated.

RESULTS

Dobutamine stress increased heart rate and cardiac output by 83% and 81%, respectively (both p < 0.0001), and mean transvalvular gradient increased from 15.6+/-5.5 mm Hg at rest to 35.4+/-11.9 mm Hg at maximum stress (p < 0.0001). Although the indexed effective orifice area was significantly lower in patients with a larger body surface area, this was not associated with any significant pressure gradient. The performance index of this valve was unchanged throughout the study. Regression analyses demonstrated that the mean transvalvular gradient at maximum stress was independent of all variables except resting gradient (p = 0.05). Body surface area had no association with the changes in cardiac output, transvalvular gradient at maximum stress, and effective orifice area.

CONCLUSIONS

These data show that the 21-mm Sorin Bicarbon bileaflet mechanical prosthesis offers an excellent hemodynamic performance with full utilization of its available orifice when implanted in the aortic position. The lack of significant transvalvular gradient in patients with a larger body surface area suggests that patient-prosthesis mismatch is highly unlikely when this prosthesis is used.

Doppler hemodynamics of 51 clinically and echocardiographically normal pulmonary valve prostheses

OBJECTIVE

To determine the normal Doppler hemodynamics of various pulmonary valve prostheses (PVPs).

PATIENTS AND METHODS

We retrospectively analyzed comprehensive Doppler echocardiographic examinations of 51 patients (mean age, 27.8 years; range, 1-59 years) with PVPs that were normal on clinical and 2-dimensional echocardiographic examinations to establish the normal hemodynamics of various types and sizes of PVPs. The earliest complete postoperative transthoracic echocardiogram was identified for each patient. Doppler examinations were analyzed for peak instantaneous velocity, right ventricular outflow tract velocity, and peak and mean systolic gradient. The frequency of prosthetic regurgitation was also noted.

RESULTS

The average +/- SD peak instantaneous velocity for all PVPs was 2.24+/-0.6 m/s, with an average peak systolic gradient of 20.4+/-10.4 mm Hg and an average mean systolic gradient of 11.0+/-5.1 mm Hg. The mean right ventricular outflow tract velocity was 1.0+/-0.2 m/s. Pulmonary homografts were found to have significantly lower peak velocities (average, 1.8+/-0.6 m/s) than all heterografts combined (average, 2.4+/-0.5 m/s; P=.002). Prosthetic regurgitation was more common in pulmonary homografts (88%) than in heterografts combined (29%; P<.001).

CONCLUSION

This study establishes the normal range for Doppler hemodynamics of various PVPs, specifically homografts and heterografts, in both pediatric and adult patients.

Left ventricular geometry and function in patients with aortic stenosis: gender differences

BACKGROUND

Gender differences in cardiac size have been described in normal and pathological conditions in human and animals. Sex determination of a pattern of hypertrophy as a response to pressure overload has not been extensively evaluated and is still poorly understood in humans.

METHODS AND RESULTS

To investigate the influence of gender in the left ventricle remodelling and preservation of the left ventricle function 195 adults (140 men and 55 women) with isolated aortic stenosis were evaluated. The mean age was 52 +/- 11 years for men and 53 +/- 13 years for women. All the patients had similar degree of aortic stenosis finally treated with valve replacement, similar clinical status and no signs of coronary artery disease in coronary angiograms. On echocardiography the left ventricle of women had a smaller the end systolic (30.5 +/- 7.8 vs. 39.4 +/- 11.2, P<0.001) and the end diastolic (49.4 +/- 9 vs. 57.3 +/- 11, P<0.001) chamber size. The female left ventricle generated a higher relative wall thickness (0.65 +/- 0.21 vs. 0.52 +/- 0.12, P<0.01), a greater fractional shortening (35.3 +/- 8.5 vs. 32.0 +/- 9.0, P<0.01) and a higher ejection fraction (64.4 +/- 12.7 vs. 57.5 +/- 14.6, P<0.001). The left ventricle posterior wall thickness and the septal thickness indexes were similar in both groups. There were also significant differences between the two groups in the left ventricle mass index.

CONCLUSIONS

Gender has an important influence on the left ventricle adaptation pattern to pressure overload due to aortic stenosis. Women developed a greater degree of left ventricle hypertrophy documented as changes in left ventricle geometry (increased relative wall thickness, left ventricular mass) and left ventricle function (fractional shortening and ejection fraction).

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.

Temporal variability of exercise Doppler echocardiography in patients with nonstented aortic bioprostheses

Temporal variability and reproducibility of Doppler-derived variables obtained during supine symptom-limited exercise was investigated in 26 patients who were in clinically and hemodynamically stable condition with normally functioning nonstented aortic bioprostheses (stentless porcine, n = 13; cryopreserved homografts, n = 13). All patients had normal systolic left ventricular function and underwent 2 similar exercise tests within 12 months (mean time interval 7.2 +/- 1.9 months). The coefficient of variation was 8% to 9% for primary Doppler-derived variables (ie, velocities and velocity time integrals) at rest and during exercise. The coefficient of variation for calculated maximal pressure difference was 16% at rest and 15% at peak exercise. Measurement variability assessed from repeated measurements from the same videotaped recording was approximately 2%. High reproducibility was shown for most variables with intraclass correlation coefficients of 0.85 or more. We conclude that Doppler echocardiography can be used in patients with nonstented aortic bioprostheses with the same high reproducibility during exercise as at rest. The results provide clinically useful information regarding temporal variability for Doppler-derived variables.

Effects of exercise on Doppler-derived pressure difference, valve resistance, and effective orifice area in different aortic valve prostheses of similar size

The effects of increased transvalvular volume flow on Doppler-derived measurements were compared in similarly sized, normally functioning, mechanical prostheses, stented and stentless porcine bioprostheses, and homografts. Homograft and stentless valves showed the largest effective orifice area and the lowest pressure differences and valve resistance at rest and during exercise-induced increase in flow rates.

[Hemodynamic evaluations of patients with small aortic annulus with St. Jude Medical prosthetic heart valve]

As the elderly population in Japan increases, senile degenerative aortic valvular disease also tends to increase. These patients often have a small aortic annulus. The problem of "valve-patient-mismatch" occurs when a small prosthesis is inserted into a patient with a small aortic annulus. To avoid annular enlargement after aortic valve replacement (AVR), we tried to use a small-sized St. Jude Medical (SJM) valve. From September 1988 through November 1996, 110 AVR were performed in our institution. In these cases, 30 underwent AVR with a small sized SJM valve (male < or = 21 mm, female < or = 19 mm). Dobutamine stress echocardiography was performed in 19 patients who had undergone AVR with a small-sized SJM valve. Surgical results were also compared between patients with small aortic annulus and those with normal-sized aortic annulus. Using Doppler echocardiography, pressure gradients (PG), cardiac index (CI), effective orifice area (EOA), and performance index (PI) were calculated at rest and during stress. The mean body surface area (BSA) of patient who had undergone AVR with SJM19A, 19HP and 21A was 1.40, 1.42 and 1.56 m2, respectively. With dobutamine stress, heart rates, PG and CI increased significantly. Mean and maximum PG of patients with 19HP (8.0 and 15.4 mmHg at rest, 12.9 and 28.0 mmHg under stress, respectively) and 21A (9.5 and 19.1 mmHg at rest, 16.5 and 35.3 mmHg under stress, respectively) were relatively low. EOA index (EOAI) of patient with 19HP showed the highest values mean 0.93 cm2/m2. PIs tended to be higher with HP models than with standard models. The tests were completed without significant side effects such as frequent ventricular arrhythmias. Among the cases with small aortic annulus, there were no operative deaths or hospital deaths. There were also no late deaths, episodes of hemorrhage or thrombosis. Conclusions. In our institution, AVR was performed safely without any aortic annular enlargement with a small aortic anulus in small BSA patients. Postoperative hemodynamic data obtained by echocardiography were satisfactory for all patients at rest and even during maximum dobutamine stress test.

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.

Dynamic evaluation of the 21-mm Medtronic Intact aortic bioprosthesis by dobutamine echocardiography

BACKGROUND

High residual transvalvular gradients have been reported with the use of small Medtronic Intact aortic valve prostheses. The aim of this study was to evaluate the hemodynamic performance of 21-mm prostheses using dobutamine Doppler echocardiography.

METHODS

Ten patients (7 women; mean age, 79 years) who had undergone aortic valve replacement with 21-mm Medtronic Intact prostheses 19.1 +/- 9.9 (standard deviation) months previously were studied. Dobutamine infusion was started at a rate of 5 microg x kg(-1) x min(-1) and increased to 10 and 20 microg x kg(-1) x min(-1) at 15-minute intervals. Pulsed and continuous-wave Doppler studies were performed at rest and at the end of each stage. Effective orifice area, performance index, and discharge coefficient of each valve were calculated, and peak and mean velocity and pressure drop across the prostheses were measured. Cardiac output was determined by Doppler measurement of flow in the left ventricular outflow tract.

RESULTS

Dobutamine stress increased heart rate and cardiac output by 68% and 65%, respectively (both p < 0.005), and mean transvalvular gradient increased from 19.1 +/- 5.1 mm Hg at rest to 33.2 +/- 7.7 mm Hg at maximum stress (p < 0.0001). Regression analyses demonstrated that maximum-stress gradient was independent of all variables except resting gradients (p < 0.004). Body surface area had no effect on the changes in cardiac output, effective orifice area, or transprosthetic gradient at maximum stress.

CONCLUSIONS

These data show that the 21-mm Medtronic Intact aortic prosthesis exhibits acceptable hemodynamic performance. Transvalvular gradients remained within a clinically acceptable range, both at rest and at maximum stress. Moreover, overall hemodynamic performance suggests that patient-prosthesis mismatch is unlikely to be a problem of clinical importance when this prosthesis is used.

Influence of the size of aortic valve prostheses on hemodynamics and change in left ventricular mass: implications for the surgical management of aortic stenosis

Discussion of aortic valve replacement has primarily concerned the choice between tissue and mechanical prostheses. Less emphasis has been placed on prosthesis size. Despite technical advances increasing prosthesis orifice area, small valves implanted in the unenlarged aortic root may not be significantly less obstructive than the stenotic native valves they replace.

METHODS

In this work we studied 52 patients (31 women, 21 men; mean age 59.2 years) in whom valve prostheses sized 19, 21, 23, or 25 mm (30 bioprostheses and 22 tilting disc valves) had been implanted to replace stenotic aortic valves. Most patients with 19 or 21 mm prostheses were women. Doppler and conventional echocardiographic studies were performed in the 10 days preceding the operation and between 10 and 40 months (mean 18 months) after the operation. The patients receiving larger valve sizes had significantly larger body surface areas than those receiving smaller valve sizes (mainly women).

RESULTS

No significant differences were observed between preoperative and postoperative diameters or left ventricular systolic function parameters, but left ventricular mass and mass index decreased in all four groups (albeit nonsignificantly in the 19 mm group, and with less statistical significance in the 21 mm group than in the 23 and 25 mm groups). Postoperative peak and mean transvalvular pressure drops were significantly greater in the 19 mm group than in the other groups, and the 21 mm group had significantly greater transvalvular pressure drops than the 25 mm group. Postoperative effective valve area was significantly smaller in the 19 mm group than in the 21 mm group, and significantly smaller in the 21 mm group than in the 23 and 25 mm groups.

CONCLUSION

We conclude that despite undeniable recent improvements in the design of artificial heart valves, 19 mm aortic prostheses continue to create significant obstruction of the left ventricular outflow tract and, possibly as a consequence of this, fail to bring about significant reduction in left ventricular hypertrophy.

Stenotic lesions

Images

Comparison of hemodynamic performances of St. Jude Medical and CarboMedics 21 mm aortic prostheses by means of dobutamine stress echocardiography

Dobutamine stress Doppler echocardiography was used to compare the hemodynamic performance of two small aortic bileaflet prostheses. Nineteen patients (14 female, mean age 64 years) who had undergone aortic valve replacement with 21 mm bileaflet valve prostheses (St. Jude Medical valve, n = 9, or CarboMedics valve, n = 10) were studied. Dobutamine infusion was started at a rate of 5 micrograms.kg-1.min-1 and increased to 10 and 20 micrograms.kg-1.min-1 at 15-minute intervals. Under maximum stress, heart rate and cardiac output increased by 70% and 120%, respectively, and mean arterial blood pressure decreased by 9%. Pulsed-wave and continuous-wave Doppler studies were performed at rest and at the end of each stage. Velocity ratio, effective orifice area, performance index, and discharge coefficient of the valve were calculated, and peak and mean velocities and pressure drops across the prostheses were measured. Dobutamine infusion produced similar increases in cardiac output in all patients. Effective orifice areas, discharge coefficients, and performance indexes were comparable for the two valve groups both at rest and maximum stress. Transvalvular velocities and pressure drops were also similar in the two valve groups. Transvalvular pressure drops were also comparable in patients with large body surface area. Dobutamine stress echocardiography is useful in the evaluation of the hemodynamic performance of prosthetic heart valves. St. Jude Medical and CarboMedics 21 mm prostheses have equally favorable hemodynamic performances in most patients under conditions of high cardiac output.

Evaluation of the hemodynamic performance of small CarboMedics aortic prostheses using dobutamine-stress Doppler echocardiography

BACKGROUND

The well-known correlation between prosthetic valve orifice area and transvalvular gradients has raised concerns about the presence of significant residual gradients when the size of the prosthesis that can be implanted is limited by the presence of a small aortic annulus.

METHODS

Dobutamine-stress Doppler echocardiography was used to evaluate the hemodynamic performance of small CarboMedics aortic prostheses (19 mm and 21 mm) in 18 patients (16 women; mean age, 64 years) who had undergone aortic valve replacement 23.5 +/- 19 months (standard deviation) previously. Dobutamine infusion was started at a rate of 5 micrograms.kg-1.min-2 and increased to 10 and 20 micrograms.kg-1.min-2 at 15-minute intervals. Pulsed and continuous wave Doppler studies were performed at rest and at the end of each stage. Effective orifice area, performance index, and discharge coefficient of both valves were calculated, and peak and mean velocity and pressure drop across the prostheses were measured.

RESULTS

Heart rate and cardiac output increased by 74% and 94%, respectively, and mean arterial blood pressure decreased by 9% at maximum stress. Effective orifice area, discharge coefficient, and performance index were comparable in both valve sizes at rest and maximum stress. Also, there was no significant difference in mean transvalvular pressure drop (gradient) for 19-mm and 21-mm prostheses at rest (8.1 +/- 8.4 and 4.8 +/- 3.8 mm Hg) or maximum stress (15.1 +/- 14.2 and 8.8 +/- 5.8 mm Hg, respectively). No significant correlation could be demonstrated between transvalvular pressure drop and patient's body surface area.

CONCLUSIONS

These data show that 19-mm and 21-mm CarboMedics aortic prostheses exhibit equally favorable hemodynamic performance with minimal pressure gradient, both at rest and under stress conditions.

How to quantitate valve regurgitation by echo Doppler techniques. British Society of Echocardiography

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