Rest and exercise Doppler hemodynamics of the Medtronic Intact aortic bioprosthesis.

BACKGROUND AND AIMS OF THE STUDY: Exercise treadmill testing was used to evaluate the functional rest and stress hemodynamic profile of the Medtronic Intact aortic bioprosthesis. METHODS: A group of 93 patients (mean age at operation 72.9 years; range: 61-79 years) was studied. Mean time to follow up was 20.8 months. The preoperative diagnosis was aortic stenosis (AS; n = 66), aortic regurgitation (AR; n = 19) or AS/AR (n = 8). Left ventricular function was assessed as normal (n = 78), moderate (n = 14) or poor (n = 1). Patients received a range of valve sizes: 21 mm (n = 7); 23 mm (n = 41); 25 mm (n = 32); 27 mm (n = 7); and 29 mm (n = 6). RESULTS: For all valve sizes, Doppler-derived hemodynamics at rest and peak exercise, respectively were: mean aortic valve gradient (AVG) 13.2 +/- 5.2 mmHg and 22.2 +/- 8.9 mmHg; peak aortic valve gradient (AVG) 24.3 +/- 9.6 mmHg and 39.1 +/- 13.5 mmHg; effective orifice area (EOA) 1.39 +/- 0.49 cm2 and 1.38 +/- 0.5 cm2; and effective orifice area index (EOAI) 0.76 +/- 0.26 cm2/m2 and 0.75 +/- 0.26 cm2/m2. Mean and peak AVG decreased as valve sizes increased, while both EOA and EOAI increased as valve sizes increased. CONCLUSIONS: The Medtronic Intact aortic bioprosthesis provides good hemodynamics both at rest and exercise, across the range of implanted valve sizes.     

Prosthetic valve hemodynamics assessed by the left ventricular outflow tract area utilization index: a randomized study of the carbomedics reduced versus the Medtronic Hall valve

BACKGROUND AND AIM OF THE STUDY: Continuous changes are made in valve prosthesis design in order to improve hemodynamic performance. In this prospective, randomized study, hemodynamic properties of the bileaflet CarboMedics Reduced (CM-R) valve with a thinner sewing ring was compared to the Medtronic Hall (MH) disc valve. Special emphasis was placed on the ability of the two valve types to make the most effective use of the available left ventricular outflow tract (LVOT) area as defined by preoperative echocardiographic measurements. METHODS: Twenty patients scheduled for a mechanical aortic valve prosthesis were randomized to receive either a CM-R or MH valve. Only patients receiving a prosthesis < or = 25 mm were included. A complete Doppler echocardiographic study was performed preoperatively and at six months postoperatively. Transprosthetic gradients, effective orifice area (EOA), effective orifice area index (EOAI) and LVOT-utilization index (LVOT-UI; defined as EOA/preoperative LVOT area) were compared. RESULTS: The CM-R valve was superior to the MH valve for all hemodynamic parameters studied: EOA 2.03 +/- 0.50 versus 1.56 +/- 0.20 cm2 (p < 0.01); EOAI 1.07 +/- 0.22 versus 0.83 +/- 0.13 cm2/m2 (p = 0.01); and LVOT-UI 0.47 +/- 0.09 versus 0.38 +/- 0.05 (p = 0.001). Although cardiac output was significantly higher in the CM-R group, transprosthetic gradients were lower (peak 21 +/- 5 versus 27 +/- 5 mmHg (p = 0.02); mean 11 +/- 4 versus 13 +/- 2 mmHg (p = 0.07)). CONCLUSION: The results of this study showed that the CM-R aortic valve offers favorable hemodynamics compared to the MH valve. The inclusion of preoperative LVOT area measurements (as LVOT-UI) showed that the CM-R offers a more effective use of the available LVOT area.     

The effective orifice area/patient aortic annulus area ratio: a better way to compare different bioprostheses? A prospective randomized comparison of the Mosaic and Perimount bioprostheses in the aortic position

BACKGROUND AND AIM OF THE STUDY: The aim of this prospective, randomized study was to compare the hemodynamic performance of the Medtronic Mosaic and Edwards Perimount bioprostheses in the aortic position, and to evaluate prosthesis-specific differences in valve sizing and valve-size labeling. METHODS: Between August 2000 and September 2002, 139 patients underwent isolated aortic valve replacement (AVR) with the Mosaic (n = 67) or Perimount (n = 72) bioprosthesis. Intraoperatively, the internal aortic annulus diameter was measured by insertion of a gauge (Hegar dilator), while prosthesis size was determined by using the original sizers. Transthoracic echocardiography was performed to determine hemodynamic and dimensional data. As the aim of AVR is to achieve a maximal effective orifice area (EOA) within a given aortic annulus, the ratio of EOA to patient aortic annulus area was calculated, the latter being based on annulus diameter measured intraoperatively. RESULTS: Operative mortality was 2.2% (Mosaic 3.0%; Perimount 1.4%; p = NS). Upsizing (using a prosthesis larger in labeled valve size than the patient's measured internal aortic annulus diameter) was possible in 28.4% of Mosaic patients and 8.3% of Perimount patients. The postoperative mean systolic pressure gradient ranged from 10.5 to 22.2 mmHg in the Mosaic group, and from 9.4 to 12.6 mmHg in the Perimount group; it was significantly lower for 21 and 23 Perimount valves than for 21 and 23 Mosaic valves. The EOA ranged from 0.78 to 2.37 cm2 in Mosaic patients, and from 0.95 to 2.12 cm2 in Perimount patients. When indexing EOA by calculating the ratio of EOA to patient aortic annulus area to adjust for variables such as patient anatomy and valve dimensions, there was no significant difference between the two bioprostheses. CONCLUSION: Comparisons of absolute EOA values grouped by the manufacturers' valve sizes are misleading because of specific differences in geometric dimensions. The EOA:patient aortic annulus area ratio provides a new hemodynamic index which may facilitate objective comparisons between different valve types.     

Transvalvular in vivo gradients of the new generation bileaflet heart valve prosthesis St. Jude Medical Regent in aortic position

BACKGROUND: By changing the design of the St. Jude Medical Regent prosthesis in shifting both sewing cuff and retaining ring into a completely supra-annular position, the Regent valve has a greater geometric orifice for a given outer diameter. Accordingly, in vitro studies have shown increased effective orifice areas (EOAs) and lower transvalvular gradients. The aim of our study was to determine in vivo transvalvular gradients and EOAs in patients after aortic valve replacement (AVR). METHODS: We investigated 75 patients at 12 to 21 months follow-up after AVR using transthoracic echocardiography. We determined left ventricular systolic and diastolic function, EOA, and transvalvular peak gradient parameters at rest. Outcomes were assessed using the NYHA classification and functional status. RESULTS: No patient experienced cardiac failure. The majority reported good functional status and good quality of life. Five (6.7 %) late deaths were observed within the surveillance period. At follow-up, 92 % of the patients had improved by at least one NYHA class. Transvalvular peak gradients at rest for patients with Regent valves were 25.4 +/- 7.7 mmHg, 19.2 +/- 4.6 mmHg, 15.6 +/- 5.8 mmHg, 14.6 +/- 5.5 mmHg, and 8.5 +/- 2.5 mmHg; EOAs were 1.38 +/- 0.32 cm2, 1.62 +/- 0.49 cm2, 2.24 +/- 0.83 cm2, 2.63 +/- 0.70 cm2, and 3.28 +/- 0.34 cm2 for valve sizes 19 mm, 21 mm, 23 mm, 25 mm, and 27 mm, respectively. CONCLUSIONS: The SJM Regent valve shows excellent in vivo hemodynamics as confirmed by echocardiography. Clinically, 92 % of the patients improved by at least one NYHA class.     

Exercise echocardiographic comparison of pulmonary autograft and aortic homograft replacements for aortic valve disease in adults

BACKGROUND AND AIM OF THE STUDY: The pulmonary autograft, or Ross procedure, has theoretical hemodynamic benefits over other aortic valve replacements. The hemodynamic performance of the pulmonary autograft and pulmonary homograft components of this procedure have not been well defined. METHODS: Twenty patients with pulmonary autograft replacement of the aortic valve and six with aortic homografts underwent exercise echocardiography with assessment of exercise duration, left ventricular dimensions, mass, and function. Hemodynamics at rest and maximal exercise, including Doppler gradients and effective orifice area (EOA), were measured across the pulmonary autograft and aortic homograft valves. Doppler gradients across the pulmonary homograft valves were compared to native pulmonary valve gradients at rest and maximal exercise. RESULTS: Both groups of patients had excellent self-reported and measured exercise capacity. In comparison to the aortic homograft, the pulmonary autograft had lower peak Doppler gradients across the neoaortic valve at rest (5 +/- 2 versus 11 +/- 4 mmHg; p = 0.027) and maximal exercise (10 +/- 5 versus 15 +/- 5 mmHg; p = 0.003) and larger indexed EOA. However, the Ross procedure patients had higher gradients across the pulmonary homograft both at rest (14 +/- 10 versus 3 +/- 1 mmHg; p < 0.001) and maximal exercise (25 +/- 22 versus 5 +/- 4 mmHg; p = 0.004). Two patients in the Ross procedure group had significant pulmonary homograft stenosis in short- or mid-term follow up. CONCLUSION: In comparison to aortic homograft replacement of the aortic valve, pulmonary autograft replacement has superior hemodynamics at rest and during exercise. However, the pulmonary homograft replacement may develop hemodynamically significant stenosis after the Ross procedure.     

Hemodynamic performance of mechanical aortic valves in narrow aortic annulus cases]

OBJECTIVE: Small-sized prosthetic valves used in aortic valve position usually cause a high transvalvular gradient. This situation, especially in people with a high body surface area, causes a patient-prosthetic valve mismatch. In this study, hemodynamic performances of the two new generation bileaflet, small size mechanical valves were evaluated during rest and stress conditions. METHODS: Eighteen patients with implanted 21-mm St. Jude HP (11 cases) and Sorin Bicarbon (7 cases) prosthetic valves in aortic position were evaluated at rest and during dobutamine infusion, 16.3+/-5.5 months after the operation. Dobutamine infusion was started at a dose of 5 microg/kg/min. The infusion rate was increased every 15 minutes up to 10-20-30 microg/kg/min. Maximum gradient, mean gradient, effective valve area (EVA), effective valve area index (EVAI) and performance index (PI) were calculated during rest and maximum dobutamine infusion rate. RESULTS: When the rest and dobutamine infusion measurements were compared, the maximum and mean gradients were found to be increased moderately, but EVA, EVAI, PI values did not change with increasing heart rates. For St. Jude valve; maximum gradient increased from 30.5+/-6.5 mmHg to 74.7+/-33.6 mmHg (p=0.03) and mean gradient increased from 17.9+/-3.8 to 40.8+/-23.8 mmHg (p=0.03). For Sorin Bicarbon valve; maximum gradient increased from 31.7+/-13.3 mmHg to 52.0+/-11.2 mmHg (p=0.01), mean gradient increased from 16.1+/-6.4 mmHg to 28.8+/-1.0 mmHg (p=0.01). The difference was not significant between the two valves with respect to measured parameters during rest and maximum dobutamine infusion. CONCLUSION: According to our findings, 21-mm Sorin Bicarbon and St. Jude HP mechanical bileaflet valves have good hemodynamic performance during exercise and these types of valves seem to be appropriate for patients with small aortic annulus.     

Comparison of On-X and SJM HP bileaflet aortic valves

BACKGROUND AND AIM OF THE STUDY: The study aim was to evaluate the hemodynamic function after aortic valve replacement (AVR) using the On-X valve, in comparison with St. Jude Medical (SJM) HP bileaflet valves. METHODS: Patients received either the On-X (n = 20) or SJM HP prosthesis (n = 20) for AVR. The control (SJM HP) group was computer-matched with the On-X group for age, gender, aortic stenosis as underlying disease, body surface area, NYHA functional class, left ventricular size, mass and function, transvalvular pressure gradients and cardiac index. Mean implanted valve size was 23.5 mm (three 21 mm, ten 23 mm, six 25 mm, one 27 mm) in both groups. All patients underwent postoperative, and six- and 12-month follow up echocardiography. RESULTS: The intra- and postoperative course was uneventful in all patients. There were no significant differences in cross-clamp and cardiopulmonary bypass times, intensive care unit stay, in-hospital stay and postoperative NYHA functional class. Two patients (both On-X) had paravalvular leakage postoperatively and at follow up. Five patients in the control group had additional myocardial revascularization. Transvalvular flow velocities were 2.38 +/- 0.3 versus 2.38 +/- 0.4 m/s (p = NS) postoperatively, and 2.08 +/- 0.2 versus 2.22 +/- 0.3 m/s (p = NS) at one year follow up for On-X and SJM HP valves, respectively. Maximum pressure gradients were 16.9 +/- 6.0 versus 18.5 +/- 8.0 mmHg (p = NS) postoperatively and 14.0 +/- 3.7 versus 16.5 +/- 5.7 mmHg (p = NS) at one year for the two valve types, respectively. A relatively pronounced transvalvular reflux was diagnosed for On-X valves. CONCLUSION: At one year after implantation, the On-X bileaflet prosthesis is equally suited for AVR in comparison with the 'standard' therapy (SJM HP). Exact sizing requires some experience. There were no significant differences between the two prostheses with regard to hemodynamic parameters either postoperatively or at one-year follow up. Long-term prospective randomized studies yet have to be carried out.     

Stented bioprosthetic valve hemodynamics: is the supra-annular implant better than the intra-annular?

BACKGROUND AND AIM OF THE STUDY: The use of stented bioprostheses for aortic valve replacement (AVR) in elderly patients with a small aortic annulus may result in unsatisfactory hemodynamic performance of the prosthesis. To overcome this limitation, new bioprostheses have been designed for complete supra-annular implantation, but the actual hemodynamic advantage of the supra-annular implant over the intra-annular has not been fully investigated. Accordingly, the hemodynamic performance of the same stented bioprosthesis (except for sewing ring design) implanted in the supra-annular and conventional intra-annular seating was compared. METHODS: Twenty-two patients received an intra-annular implant, and 38 a supra-annular implant. Age (74 +/- 5 versus 76 +/- 5 years, p = 0.54), gender (55% versus 50% males, p = 0.79) and body surface area (1.74 +/- 0.2 versus 1.81 +/- 0.2 m2, p = 0.13) were similar in both subgroups, who underwent echocardiography at 8 +/- 2 and 6 +/- 2 months after surgery, respectively (p = 0.09). RESULTS: The two patient subgroups had similar preoperative left ventricular outflow tract diameters (2.06 +/- 0.2 and 2.1 +/- 0.2 cm; p = 0.62), average size of implanted prosthesis (21.0 and 21.3 mm; p = 0.44) and mean transprosthetic flow rate (246 +/- 70 and 218 +/- 58 ml/s; p = 0.12). Mean (8 +/- 3 and 19 +/- 8 mmHg, p < 0.0001), and peak (17 +/- 6 and 40 +/- 13 mmHg; p < 0.0001) transprosthetic gradients were lower, and mean effective orifice area (EOA) (1.78 +/- 0.4 and 1.45 +/- 0.5 cm2, p = 0.006) was higher in patients with supra-annular implants than in those with intraannular. The incidence of patient-prosthesis mismatch (EOA index < 0.85 cm2/m2) decreased from 50% to 34% (p < 0.0001), with no case of severe mismatch using the supra-annular implant. During follow up, a left ventricular mass reduction occurred in patients with supra-annular implants (from 225 +/- 110 to 173 +/- 59 g/m2; p < 0.03), but not in patients with intra-annular implants (173 +/- 62 and 186 +/- 64 g/m2; p = 0.87) CONCLUSION: The study results showed that, compared to intra-annular implantation, supra-annular implantation of bioprosthetic stented valves in the aortic position was associated with a significantly better hemodynamic performance of the prosthesis and significant regression of left ventricular hypertrophy.     

Impact of small valve size on hemodynamics and left ventricular mass regression with the Toronto SPV stentless aortic bioprosthesis

BACKGROUND AND AIM OF THE STUDY: The hemodynamic performance of stentless aortic bioprostheses has been previously well described. Because the potential for prosthesis-patient mismatch is greatest for small valves in the aortic position, the present study sought to compare the hemodynamic performance and degree of left ventricular (LV) mass regression between valve sizes for the Toronto SPV valve, with special interest in measures of relief of LV outflow obstruction afforded by the smallest valves. METHODS: This study included 257 patients (178 men, 79 women; mean age 63.5+/-11.4 years; range: 34-93 years) from six investigative centers with complete echocardiography/Doppler data obtained through three years. Valve sizes implanted were 21 mm (n = 11), 23 mm (n = 23), 25 mm (n = 58), 27 mm (n = 83), and 29 mm (n = 82). Echocardiography was performed at discharge, six months, one year, and yearly thereafter, and interpreted in a centralized core laboratory. Mean gradient, effective orifice area (EOA), indexed EOA, and absolute and percent change in LV mass index were used as markers of hemodynamic performance. RESULTS: For all valve sizes, mean and peak gradients fell and EOA increased early after surgery. There were no differences between groups in the degree to which gradients fell, and EOA increased from discharge to one year follow up. At one year, indexed EOA was 0.9 cm2/m2 for valve sizes 21 and 23 mm, and 1.0-1.2 cm2/m2 for sizes 25, 27 and 29 mm. There was statistically significant LV mass regression for all valve sizes (p <0.05), and no differences between valve sizes in the magnitude of absolute or percent change in LV mass index between baseline and three years. CONCLUSION: The Toronto SPV valve demonstrates excellent parameters of hemodynamic performance for all valve sizes, including the smallest valves used in only a minority of patients. Findings of indexed EOA > or = 0.9 cm2/m2, and equivalent degrees of LV mass regression for all valve sizes, reinforces the excellent hemodynamic performance of stentless aortic bioprostheses, and suggests that prosthesis-patient mismatch should be minimized with these valves.     

Impact of patient-prosthesis mismatch and aortic valve design on coronary flow reserve after aortic valve replacement.

OBJECTIVES: This prospective-randomized study investigated the effect of aortic valve design and patient-prosthesis mismatch (PPM) on coronary flow reserve (CFR) after mechanical or biological aortic valve replacement (AVR) in patients with aortic stenosis (AS). BACKGROUND: Coronary flow reserve may be an important parameter of long-term survival after AVR in patients with AS. Reduced CFR may contribute to more cardiovascular events and greater rates of mortality. METHODS: A total of 48 patients undergoing AVR underwent magnetic resonance imaging for the measurement of coronary flow preoperatively, 5 days postoperatively, and at 6-month follow-up with measurement of CFR. Patients scheduled for mechanical AVR were randomized to a tilting disc or bileaflet prosthesis (n = 12 in each group). For biological AVR, patients were scheduled to receive a stented (n = 12) or stentless (n = 12) valve. Patients also underwent echocardiography with measurement of transvalvular pressure gradients and left ventricular mass regression. RESULTS: Postoperatively, coronary flow increased significantly in all groups (p < 0.001). Only stentless valves demonstrated a normal CFR (3.4 +/- 0.3 vs. 2.3 +/- 0.1 for stented biological valves, 2.1 +/- 0.2 for tilting disc, and 2.2 +/- 0.3 for bileaflet mechanical valves). Patient-prosthesis mismatch with an indexed effective orifice area <0.85 cm2/m2 led to decreased rates of CFR in the tilting disc, stentless, and stented groups. Pressure gradients were 14 +/- 3 mm Hg for tilting disc, 12 +/- 4 mm Hg for bileaflet, 19 +/- 6 mm Hg for stented, and 10 +/- 4 mm Hg for stentless valves. CONCLUSIONS: Normalization of CFR after AVR in patients with AS was observed only for stentless valves. Coronary flow reserve might explain the excellent long-term results for stentless valves. (Impact of Patient-Prosthesis Mismatch on Coronary Flow Reserve; http://www.clinicaltrials.gov/ct/show/NCT00310947?order=1; NCT00310947).     

The Toronto root stentless valve in the subcoronary position is hemodynamically superior to the mosaic stented completely supra-annular bioprosthesis

BACKGROUND AND AIM OF THE STUDY: Stentless valves are considered to exhibit better hemodynamics after aortic valve replacement (AVR) compared to stented valves. However, a new generation of stented bioprostheses for completely supra-annular implantation has been designed to optimize the ratio of the effective orifice area (EOA) of the prosthesis and aortic annulus area. The study aim was to determine whether a stentless valve implanted in the subcoronary technique renders larger orifice areas and lower transvalvular pressure gradients at rest and exercise compared to a completely supra-annular stented device. METHODS: Twenty patients underwent AVR for aortic stenosis with the St. Jude Medical (SJM) Toronto Root stentless porcine bioprosthesis, using a subcoronary implantation technique. Through the authors' institutional database, 20 additional patients were identified who had undergone AVR with the Medtronic Mosaic stented completely supra-annular porcine bioprosthesis. The patient groups were not matched for labeled valve size, but for annulus diameter measured intraoperatively using Hegar's dilators. Hemodynamic performance was assessed by transthoracic echocardiography at discharge (early) and by rest and stress echocardiography at six months postoperatively (mid-term). RESULTS: Transvalvular mean pressure gradients (MPG) at rest were significantly lower in the stentless group, but cardiac output was similar in both groups. Stress echocardiography also revealed significantly lower gradients at 25 W and 50 W exercise in the stentless group. The EOA index (EOAI), grouped by annulus diameter, tended to be larger in the stentless group and showed no severe patient-prosthesis mismatch (PPM; EOAI <0.65 cm2/m2) which, in contrast, occurred in three patients (15%) in the stented group (p = 0.072). CONCLUSION: In summary, the SJM Toronto Root porcine stentless bioprosthesis in the subcoronary position showed lower MPGs and larger EOAs at rest and during exercise compared to the Medtronic Mosaic porcine stented bioprosthesis. Therefore, physically active patients in particular may benefit from use of the stentless valve. Because of its larger EOA, a stentless valve should be implanted if severe PPM is expected.     

Exercise hemodynamic performance of the pulmonary autograft following the Ross procedure.

BACKGROUND AND AIMS OF THE STUDY: The Ross procedure, in which the aortic valve is replaced with the patient's own pulmonary valve (pulmonary autograft), is considered an excellent alternative for younger patients requiring elective aortic valve replacement. Although resting pulmonary autograft hemodynamics are excellent, exercise hemodynamic data are lacking. The study aim was to measure the hemodynamic performance of the pulmonary autograft with exercise Doppler echocardiography (DE). METHODS: Twenty-four Ross procedure patients (20 males, four females; mean age 46 +/- 11 years) were studied at 25 +/- 14 months after aortic valve replacement with a pulmonary autograft. Patients had baseline supine DE to measure the maximum velocity (Vmax), and the peak and mean pressure gradient across the pulmonary autograft. Effective orifice area was calculated from the continuity equation and indexed to body surface area (EOAi). Patients then underwent symptom-limited upright bicycle exercise with supine DE repeated immediately on stopping exercise. For comparison, 10 normal controls (age 41 +/-10 years) and five mechanical aortic valve patients (mean age 55 +/- 10 years) were studied. RESULTS: At rest: Ross procedure patients had similar Vmax (1.2 +/- 0.2 m/s), peak gradient (6 +/- 2 mmHg), mean gradient (4 +/- 1 mmHg) and EOAi (1.7 +/- 0.4 cm2/m2) to those of normal controls. Mechanical-valve patients had significantly higher Vmax (2.5 +/- 0.2 m/s, p <0.001), peak gradient (25 +/- 4 mmHg, p <0.001) and mean gradient (14 +/- 3 mmHg, p <0.001) than Ross patients and normal controls. At exercise: Ross procedure patients had similar Vmax (1.8 +/- 0.4 m/s versus 2.1 +/- 0.2, p = NS), peak gradient (14 +/- 6 mmHg versus 17 +/- 4, p = NS) and mean gradient (8 +/- 4 mmHg versus 10 +/- 2, p = NS) to normal controls, with no significant change in EOAi. Mechanical-valve patients had significantly higher Vmax (3.4 +/- 0.3, p <0.001), peak gradient (48 +/- 7 mmHg, p <0.001) and mean gradient (30 +/- 5 mmHg, p <0.001) than Ross patients and normal controls. CONCLUSIONS: Aortic valve replacement using the Ross procedure provides excellent hemodynamic results at rest and on exercise, with DE parameters indistinguishable from those of normal controls. This study provides further support for the use of the Ross procedure as a preferred method of aortic valve replacement in younger patients.     

Hemodynamic evaluation of the Sorin Soprano bioprosthesis in the completely supra-annular aortic position

BACKGROUND AND AIM OF THE STUDY: The study aim was to evaluate the clinical and hemodynamic performance of the Sorin Soprano bioprosthesis in the aortic position. METHODS: Rest and stress echocardiography were performed at six months after surgery in 57 patients who underwent aortic valve replacement with the stented Soprano bioprosthesis. The exercise protocol included workloads of 25, 50, 75 and 100 W, each of 2 min duration. RESULTS: Thirty-day mortality was 1.8% (n = 1). Due to malperfusion of the coronary arteries, two Soprano prostheses had to be replaced by a different prosthesis, and one patient received coronary artery bypass grafts. One patient developed bacterial endocarditis of his prosthesis at seven months postoperatively and died as a result of a fulminant sepsis. There were no other prosthesis-related adverse events. Mean pressure gradients (MPG) ranged from 7.8 to 15.9 mmHg, effective orifice areas (EOA) from 1.25 to 2.98 cm2, EOA index (EOAI) from 0.79 to 1.43 cm2/m2, and EOA fraction from 34 to 45%. Stress echocardiography showed no significant increase in MPG up to 50 W, and MPGs did not exceed 35 mmHg at 75 and 100 W. CONCLUSION: Initial hemodynamic results showed low MPGs during rest and exercise. The EOAI was large due to completely supra-annular placement of the Soprano valve. The difficulty of complete supraannular placement is that the prosthesis is positioned relatively high, especially in narrow aortic roots, and this may handicap coronary artery perfusion. Patient selection with suitable aortic root anatomy is crucial to achieve the benefit of completely supra-annular implantation without coronary ostium deterioration.     

Usefulness of the indexed effective orifice area at rest in predicting an increase in gradient during maximum exercise in patients with a bioprosthesis in the aortic valve position

This study examines the hemodynamic behavior of aortic bioprosthetic valves during maximum exercise. Nineteen patients with a normally functioning stented bioprosthetic valve and preserved left ventricular function were submitted to maximum ramp bicycle exercise. In 14 of the 19 patients, valve effective orifice area and mean gradient were measured at rest and during exercise using Doppler echocardiography. At peak exercise (mean maximal workload 118 +/- 53 W), the cardiac index increased by 122 +/- 34% (+3.18 +/- 0.71 L/min/ m2, p <0.001), whereas mean gradient increased by 94 +/- 49% (+12 +/- 8 mm Hg, p <0.001), and effective orifice area by 9 +/- 13% (+0.15 +/- 0.22 cm2, p = 0.02). A strong correlation was found between the increase in mean gradient during maximum exercise and the valve area at rest indexed for body surface area (r = 0.84, p <0.0001). Due to the increase in valve area, the increase in gradient was less (-9 +/- 7 mm Hg, -41 +/- 33%, p = 0.0006) than theoretically predicted assuming a fixed valve area. These results suggest that the effective orifice area of the bioprostheses has the capacity to increase during exercise; therefore, limiting the increase in gradient. The relation found between the indexed effective orifice area at rest and the increase in gradient during exercise should be useful in predicting the hemodynamic behavior of a stented bioprosthesis during exercise.     

Impact of mechanical and biological aortic valve replacement on coronary perfusion: a prospective, randomized study

BACKGROUND AND AIM OF THE STUDY: Coronary perfusion is impaired in patients with aortic stenosis (AS). Aortic valve replacement (AVR) leads to improvement, but not complete restoration, of coronary flow. Previous studies have shown that postoperative coronary flow rate and coronary reserve in mechanical valves is dependent on valve design and orientation. The study aim was to investigate acute changes in coronary perfusion in patients undergoing mechanical or biological valve replacement in a prospective, randomized clinical study. METHODS: Forty patients undergoing AVR for AS underwent MRI scanning to measure coronary flow preoperatively and at five days after surgery. Patients scheduled for mechanical AVR (n = 20) were randomized to a tilting disc (Medtronic Hall) or bileaflet (Medtronic ADVANTAGE) prosthesis; the biological-valve group (n = 20) received a stented (Medtronic Mosaic) or stentless (Medtronic Freestyle) valve. Valve sizes were comparable in all groups. Patients also underwent echocardiography both preoperatively and postoperatively to measure transvalvular pressure gradients. The rate-pressure product (RPP) was calculated as a marker of myocardial oxygen demand and cardiac workload. RESULTS: The mean preoperative coronary flow rate was 90 +/- 32 ml/min, and this increased after AVR in all patients. The rise in the mechanical-valve groups was comparable for the two tested valves, whereas in the biological-valve groups a significantly higher increase for stentless valves was present (p < 0.05). Mean pressure gradients for the Hall and ADVANTAGE valves were equal; for biological valves, the Mosaic demonstrated a higher mean gradient (19 +/- 6 mmHg) than the Freestyle (10 +/- 4 mmHg) (p < 0.05). The RPP was lower for ADVANTAGE (mechanical group) and for Freestyle valves (biological group). CONCLUSION: Coronary artery flow was increased following AVR in all valve groups. The rise was significantly more distinct for Medtronic Freestyle stentless valves compared to the three other valve substitutes. As the stentless design also demonstrated superior hemodynamics and a lower myocardial oxygen demand with lower pressure gradients and lower RPP, this may have a positive impact on the clinical long-term outcome of this valve.     

A single-center experience of the Sorin Bicarbon heart valve prosthesis: long-term clinical, hematological and hemodynamic results

BACKGROUND AND AIM OF THE STUDY: The Sorin Bicarbon (SB) bileaflet valve, available since 1990, has a good clinical safety profile. The study aim was to assess the long-term clinical results following implantation, plus hemodynamic and hematological aspects of the valve. METHODS: A total of 195 SB prostheses (100 aortic, 67 mitral, 14 double valve replacements) was implanted in 181 patients (108 males, 73 females) since 1991. RESULTS: Mean age at implantation was 60.5 +/- 10.8 years. Actuarial analysis at 9.0 years showed an overall survival of 63.9 +/- 5.5%; 28.2% of deaths were early (n = 11), and 71.8% late (n = 28). Freedom from thrombosis was 99.4 +/- 0.6% (one early event, successfully reoperated on), and from embolic events was 86.3 +/- 4.7%. Freedom from endocarditis and hemorrhagic complications were respectively 98.1 +/- 1.1% and 98.6 +/- 0.9%. No occurrence of hemolysis was reported. Freedom from non-structural valve dysfunction was 98.7 +/- 0.9%, and from reoperation was 96.1 +/- 1.6%. Hemodynamic evaluation by echocardiography and hematological testing was performed at 7.0 +/- 1.3 years (range 5-9 years) in a subset of 31 patients (20 males, 11 females). Mean valve size was 23.9 mm for aortic mitral. Echocardiography showed that aortic valves had a mean effective orifice area (EOA) of 2.26 +/- 1.28 cm2, with peak and mean pressure gradients of 23.6 +/- 14.6 and 12.9 +/- 8.1 mmHg, respectively. The mean EOA of mitral valve prostheses was 2.67 +/- 0.66 cm2, with peak and mean pressure gradients of 12.2 +/- 4.5 and 3.8 +/- 1.6 mmHg, respectively. Overall mean hemoglobin was 13.4 +/- 1.35 g/dl, and serum lactate dehydrogenase 630 +/- 13 IU/l. Serum haptoglobin was detectable in one patient only, and the mean reticulocyte count was 1.24 +/- 0.51%. CONCLUSION: In the present authors' experience, the Sorin Bicarbon prosthesis has low complication rates and maintains an excellent hemodynamic function over time. Hemolytic potential is insignificant with this valve.     

Experience with the Edwards MIRA mechanical bileaflet valve in the aortic and mitral positions

The Edwards MIRA bileaflet mechanical prosthesis, a heart valve not yet available in the United States, is designed with a unique hinge mechanism, curved leaflets, and thin titanium housing. We performed this study to investigate its clinical performance and postoperative hemodynamic results. We implanted 58 Edwards MIRA prostheses in 51 patients in the aortic (n = 18), mitral (n = 26), and aortic and mitral (n = 7) positions. Patients' ages ranged from 25 to 84 years (mean age, 53.7 +/- 13.6). Operative mortality was 2% (n = 1), and late mortality was 4% (n = 2). Thromboembolic events were observed in 2 patients (valve thrombosis in 1 and a cerebrovascular event in 1). There were no complications related to anticoagulation. No signs of valvular dysfunction or paravalvular leakage were observed. Peak transvalvular gradients of the aortic prostheses ranged from 24.25 +/- 5.32 mmHg for the 21-mm valve to 11 +/- 1.41 mmHg for the 25-mm valve. The effective orifice area ranged from 1.99 +/- 0.12 cm2 for the 21-mm valve to 2.44 +/- 0.17 cm2 for the 25-mm valve. The mean transvalvular gradients of the mitral prostheses ranged from 5.85 +/- 2.91 mmHg for the 27-mm valve to 4.5 +/- 0 mmHg for the 31-mm valve. The effective orifice area ranged from 2.31 +/- 0.03 cm2 for the 27-mm valve to 2.64 +/- 0.05 cm2 for the 33-mm valve. These preliminary data suggest good hemodynamic function and a low rate of valve-related complications in the use of the Edwards MIRA mechanical prosthesis.     

The stentless quadrileaflet bovine pericardial mitral valve: echocardiographic assessment

BACKGROUND AND AIMS OF THE STUDY: Recently, a stentless chordally supported quadrileaflet mitral valve (QMV) bioprosthesis made of selected tanned bovine pericardium treated to minimize calcification, has become available for clinical trial. The aim of this study was to report both the echocardiographic appearance and hemodynamic performance of this valve by means of echocardiography. METHODS: The QMV was implanted in 22 patients (mean age 38 +/- 12 years) requiring isolated mitral valve replacement for valve lesions not deemed suitable for repair. Echocardiography was performed pre-operatively, and at one and three months postoperatively. Transthoracic echocardiography (TTE) was used to monitor mean instantaneous pressure gradient as calculated from the long modified Bernoulli equation, cardiac index (CI), pressure half-time and effective orifice area (EOA) using the Hatle and continuity equations. Regurgitation patterns were sought by color Doppler transesophageal echocardiography in all valves intraoperatively following valve implantation, and by TTE in the outpatient clinic at follow up. RESULTS: After a mean follow up of 8.3 months (range: 1 to 18 months), all patients were well and symptomatically improved. At three months postoperatively, the mean pressure gradient ranged from 1.7 to 2.2 mmHg. The EOA was larger using the Hatle as compared with the continuity equation (2.4 +/- 0.7 cm2 versus 1.8 +/- 0.5 cm2, respectively; p < 0.005). Mitral regurgitation was trivial in 77% and mild in 14% of patients at 3 months after surgery; moderate mitral stenosis was noted in one patient. The CI improved significantly postoperatively (p < 0.005), and left ventricular function was maintained. CONCLUSIONS: The hemodynamic performance of this novel prosthesis is favorable. Although follow up is too short to assess durability, it is hoped that the unique design and improved valve preservation technique of this device will enhance long-term durability.     

Primary results with the new Hall-Kaster disc valve prosthesis in mitral position.

The Hall-Kaster central flow prosthetic heart valve was introduced in 1977 in an attempt to improve the hemodynamics of the disc valve prostheses. Towards this accomplishment, innovations in the tilting axis, the disc guidance mechanisms, and disc translational freedom cooperate to improve flow through both orifice segments of the open valve. The present study reports on the primary clinical and hemodynamic findings in the first 20 patients (mean age 57.6 years) with isolated mitral valvular disease, examined 3--4 months after insertion of the Hall-Kaster disc valve prosthesis. The hemodynamic findings displayed low gradients and high calculated valve areas (5). At rest, the mean diastolic pressure gradient across the smallest prosthesis used (O.D. 27) averaged 3.0 mmHg, vs. 2.6 mmHg across the largest valve sizes (O.D. 29--31). Calculated valve area was on an average 3.08 cm2 for the smaller valve, and 3.47 cm2 for the larger valves, which corresponded to an utilization of 81% and 77% of the orifice area measured in vitro. A comparison with earlier studies of mean diastolic mitral gradients with different mitral prostheses indicates that the Hall-Kaster disc valve represents an improvement towards a hemodynamically more efficient prosthesis for mitral valve replacement.     

Left ventricular mass regression after aortic valve replacement with the new Mitroflow 12A pericardial bioprosthesis

BACKGROUND AND AIM OF THE STUDY: The study aim was to evaluate the durability of the new Mitroflow 12A pericardial bioprosthesis and to assess ventricular mass regression after aortic valve replacement (AVR) in patients with small valves. METHODS: A total of 326 Mitroflow 12A pericardial bioprostheses was implanted without any other associated valve procedure. The mean patient age was 73.5 +/- 6.1 years; 252 patients (78.0%) were in NYHA class III/IV. Small valves (19 and 21 mm) were implanted in 212 patients (65.6%). The total follow up period was 837.1 patient-years (pt-yr). A subset of 61 patients with preoperative stenosis was selected and submitted to conventional echo-Doppler assessment at a mean period of 11.1 months after surgery. RESULTS: Hospital mortality was 8.6%. At eight years of follow up, survival was 57.1%. Freedom from structural valve deterioration (SVD) was 86.5% per pt-yr. Mean gradients were significantly reduced postoperatively for each valve size (to 18 +/- 8 mmHg for 19-mm valves and 12 +/- 4 mmHg for 25-mm valves). The effective orifice area (EOA) was also increased significantly for all valve sizes (to 1.1 +/- 0.1 cm2 for 19-mm valves and 1.8 +/- 0.2 cm2 for 25-mm valves). The left ventricular mass index (LVMI) decreased significantly, from 177 +/- 29 to 136 +/- 22 g/m2 for the 19-mm valve, and from 200 +/- 42 to 132 +/- 22 g/m2 for the 25-mm valve. The EOA index (EOAI) showed mismatch for the 19- and 21-mm valves (0.74 and 0.82 cm2/m2, respectively). The diagrammatic calculation between LVMI and relative wall thickness after surgery showed that 29.7% of patients achieved a normal pattern of remodeling (including 19- and 21-mm valves), despite various degrees of mismatch. CONCLUSION: The new Mitroflow 12A pericardial bioprosthesis showed an absence of mechanical failure after an eight-year follow up, with a satisfactory rate of SVD. Significant reductions in LVMI and improved ventricular geometry were observed, despite the small valve sizes implanted.