Aortic valve replacement for aortic stenosis after previous coronary artery bypass grafting: could early reoperation be prevented?

BACKGROUND AND AIM OF THE STUDY: The study aim was to examine, retrospectively, the risk of accelerated progression of aortic stenosis (AS) and outcome after aortic valve replacement (AVR) in patients who had undergone previous coronary artery bypass graft (CABG) surgery. METHODS: Between 1994 and 2004, 81 patients with mild-to-moderate AS at the time of CABG underwent subsequent AVR. The mean EuroScore was 10.8 +/- 1.8. The population was divided into three subgroups according to the time interval between AVR and CABG: group A, < 5 years (n = 23); group B, 5-10 years (n = 34); and group C, > 10 years (n = 24). RESULTS: Mean age at the time of CABG was 70 +/- 5, 64 +/- 6 and 58 +/- 5 years in groups A, B, and C, respectively. The peak transvalvular gradient was < or = 30 mmHg in 65 patients (80.2%), and 30-50 mmHg in 16 (19.7%). Operative mortality after AVR was 16% in the overall population (30%, 11.7%, and 8.6% in groups A, B, and C, respectively). The mean time interval between CABG and AVR was 8.9 +/- 5.2 years. By multivariate analysis, a peak transvalvular gradient > or = 30 mmHg (p = 0.003), moderate calcifications with moderately-to-severely limited valve motion (p = 0.05), and left ventricular hypertrophy (LVH) (p = 0.005) were independent predictors of AVR within five years of CABG surgery. Systemic vascular atherosclerotic disease was a predictor of rapid disease progression by univariate analysis, and a predictor of operative mortality by multivariate analysis. CONCLUSION: Because of the high mortality associated with repeat operations within five years, AVR should be considered at the time of CABG in patients aged < or = 75 years, with a peak transvalvular gradient > 30 mmHg, moderately prominent calcifications with moderately to severely limited valve motion, and LVH.     

Survival after aortic valve replacement for severe aortic stenosis with low transvalvular gradients and severe left ventricular dysfunction

OBJECTIVE: We sought to assess whether aortic valve replacement (AVR) among patients with severe aortic stenosis (AS), severe left ventricular (LV) dysfunction and a low transvalvular gradient (TVG) is associated with improved survival. BACKGROUND: The optimal management of patients with severe AS with severe LV dysfunction and a low TVG remains controversial. METHODS: Between 1990 and 1998, we evaluated 68 patients who underwent AVR at our institution (AVR group) and 89 patients who did not undergo AVR (control group), with an aortic valve area < or = 0.75 cm(2), LV ejection fraction < or = 35% and mean gradient < or = 30 mm Hg. Using propensity analysis, survival was compared between a cohort of 39 patients in the AVR group and 56 patients in the control group. RESULTS: Despite well-matched baseline characteristics among propensity-matched patients, the one- and four-year survival rates were markedly improved in patients in the AVR group (82% and 78%), as compared with patients in the control group (41% and 15%; p < 0.0001). By multivariable analysis, the main predictor of improved survival was AVR (adjusted risk ratio 0.19, 95% confidence interval 0.09 to 0.39; p < 0.0001). The only other predictors of mortality were age and the serum creatinine level. CONCLUSIONS: Among select patients with severe AS, severe LV dysfunction and a low TVG, AVR was associated with significantly improved survival.     

Left ventricular remodeling early after aortic valve replacement: differential effects on diastolic function in aortic valve stenosis and aortic regurgitation

OBJECTIVES: The aim of this study was to evaluate the effect of aortic valve replacement (AVR) on left ventricular (LV) function and LV remodeling, comparing patients with aortic valve stenosis to patients with aortic regurgitation. BACKGROUND: Aortic valve disease is associated with eccentric or concentric LV hypertrophy and changes in LV function. The relationship between LV geometry and LV function and the effect of LV remodeling after AVR on diastolic filling, in patients with aortic valve stenosis compared with aortic regurgitation, are largely unknown.Nineteen patients with aortic valve disease (12 aortic valve stenosis, 7 aortic regurgitation) were studied using magnetic resonance imaging to assess LV geometry and LV function before and 9 +/- 3 months after AVR. Ten age-matched healthy males served as control subjects. RESULTS: Before AVR, the ratio between left ventricular mass index (LVMI) and left ventricular end-diastolic volume index (LVEDVI) was only increased in patients with aortic valve stenosis (1.37 +/- 0.16 g/ml) compared with control subjects (0.93 +/- 0.08 g/ml, p < 0.05). After AVR, LVMI/LVEDVI decreased significantly in aortic valve stenosis (to 1.15 +/- 0.14 g/ml, p < 0.0001), but increased significantly in aortic regurgitation (1.02 +/- 0.20 g/ml to 1.44 +/- 0.27 g/ml, p < 0.0001). Before AVR, diastolic filling was impaired in both aortic valve stenosis and aortic regurgitation. Early after AVR, diastolic filling improved in patients with aortic valve stenosis, whereas patients with aortic regurgitation showed a deterioration in diastolic filling. CONCLUSIONS: Early after AVR, patients with aortic valve stenosis show a decrease in both LVMI and LVMI/LVEDVI and an improvement in diastolic filling, whereas in patients with aortic regurgitation, LVMI decreases less rapidly than LVEDVI, causing concentric remodeling of the LV, most likely explaining the observed deterioration of diastolic filling in these patients.     

In-vivo analysis of the instantaneous transvalvular pressure difference-flow relationship in aortic valve stenosis: implications of unsteady fluid-dynamics for the clinical assessment of disease severity

BACKGROUND AND AIM OF THE STUDY: Because the hemodynamic basis of aortic valve area (AVA) has never been validated in vivo, several alternative indices have been proposed to quantify the severity of aortic stenosis (AS). This study was designed to assess the fluid-dynamics of aortic valve stenosis in order to clarify which index best accounts for disease severity. The diagnostic implications of reversed deltaP during ejection were also investigated. METHODS: Chronic valvular AS characterized by stiff leaflets without commissural fusion was created surgically in eight adult mongrel dogs; three additional animals were used as controls. At two-week intervals (three studies per dog), simultaneous micromanometer pressure and transit-time Q measurements were collected under different hemodynamic conditions. Instantaneous deltaP and Q signals were processed digitally and fitted to a modified form of the unsteady Bernoulli equation in which AS is characterized by effective valve area. RESULTS: An unsteady Bernoulli equation accurately predicted measured instantaneous AP values (R = 0.97+/-0.06), and a quadratic correlation was observed between instantaneously fitted and Gorlin-derived AVA. Additionally, deltaP < 0 mmHg during late ejection was observed in the majority of AS datasets, with a normalized time to deltaP reversal of 93+/-13% for AS animals versus 69+/-36% for controls (p <0.0005). Time to deltaP reversal inversely correlated with the Strouhal number (R = -0.77), and was responsible for an overestimation of mean systolic transvalvular deltaP and Q that resulted in a significant bias in the Gorlin method. Error was highest in moderate stenosis with low transvalvular output. CONCLUSION: Unsteady fluid-dynamics supports AVA over other measures of AS such as aortic valve resistance. However importantly, late-ejection reversal of deltaP precludes estimating the systolic ejection period from pressure tracings, and accounts for an additional source of error when AS is quantified invasively.     

Valve structure and survival in octogenarians having aortic valve replacement for aortic stenosis (+/- aortic regurgitation) with versus without coronary artery bypass grafting at a single US medical center (1993 to 2005)

The purpose of this study was to determine the effect of simultaneous coronary artery bypass grafting (CABG) and valve structure on both early and late survival in octogenarians having aortic valve replacement (AVR) for aortic stenosis (AS) (with or without aortic regurgitation). Although a number of reports are available in octogenarians having AVR for AS, none have described aortic valve structure. Most have limited numbers of patients and few have described late results. We analyzed survival and valve structure in 196 octogenarians having AVR for AS from 1993 to 2005 at Baylor University Medical Center, including 118 (60%) with and 78 (40%) without simultaneous CABG. Sixty-day mortality, which was identical to 30-day mortality, was similar (10% and 11%) in the groups with and without simultaneous CABG. Unadjusted analysis of late survival (up to 13 year follow-up) was not affected by gender (male vs female), aortic valve structure (bicuspid vs tricuspid) or preoperative severity of the AS (transvalvular peak pressure gradient > 50 vs < or =50 mm Hg), or by performance of CABG. Of the 196 patients, 54 (28%) had a congenitally bicuspid aortic valve, and 142 (72%) had a tricuspid aortic valve. In conclusion, gender, valve structure, preoperative severity of the AS, or performance of simultaneous CABG did not effect survival in octogenarians having AVR for AS.     

Valve structure and survival in sexagenarians having aortic valve replacement for aortic stenosis (+/-aortic regurgitation) with versus without coronary artery bypass grafting at a single US medical center (1993 to 2005)

The purpose of this study was to determine the effect of simultaneous coronary artery bypass grafting (CABG) and the influence of valve structure on both early and late survival in sexagenarians having aortic valve replacement (AVR) for aortic stenosis (AS) (with or without aortic regurgitation). We analyzed survival and valve structure in 289 sexagenarians having AVR for AS from 1993 through 2005 at Baylor University Medical Center, including 147 (51%) with and 142 (49%) without simultaneous CABG. Of the 282 patients with information available, 13 (4.6%) died within 30 days of operation and 1 additional patient, from 31 to 60 days after operation (5.0% 60-day mortality). Sixty-day mortality was similar (6% and 4%) in the groups with and without simultaneous CABG. A total of 66 patients (23%) died from >60 days up to 13 years postoperatively. The unadjusted survival analysis showed that late survival was not affected by gender (male versus female), aortic valve structure (unicuspid, bicuspid, and quadricuspid versus tricuspid) or preoperative severity of the AS (transvalvular peak pressure gradient >50 mm Hg versus < or =50 mm Hg), or by performance of CABG. The aortic valve was congenitally unicuspid in 10 patients (3%), congenitally bicuspid in 170 (59%), 3-cuspid in 107 (37%), congenitally quadricuspid in 1 patient, and the valve structure was indeterminate in 1 patient. In conclusion, gender, valve structure, preoperative severity of the AS, or performance of simultaneous CABG did not effect unadjusted survival in sexagenarians undergoing AVR for AS.     

Low-level exercise echocardiography fails to elicit left ventricular contractile reserve in patients with aortic stenosis, reduced ejection fraction, and low transvalvular gradient

BACKGROUND: Low-level exercise echocardiography is useful to assess left ventricular (LV) contractile reserve after an acute myocardial infarction. Whether low-level exercise can elicit LV contractile reserve in patients with severe aortic stenosis, reduced LV systolic function and low transvalvular gradient are unknown. Accordingly, the value of low-level exercise to elicit contractile reserve was assessed in these patients using dobutamine administration as the gold standard method. METHODS AND RESULTS: Seventeen patients with severely decreased aortic valve area (0.75 +/- 0.03 cm(2)), reduced LV ejection fraction (35 +/- 2%) and low mean transvalvular gradient (23 +/- 3 mmHg) underwent low-level exercise and dobutamine echocardiography. Ejection fraction increased by 23% (P < 0.001) with dobutamine and decreased by 8% (P = 0.2) with low-level exercise. Left ventricular outflow tract velocity time integral increased from 13 +/- 1 to 16.7 +/- 1 cm (P < 0.001) with dobutamine but did not change with low-level exercise (13 +/- 1 vs. 13.5 +/- 1, P = 0.5). CONCLUSION: Low-level exercise fails to elicit LV contractile reserve in patients with severe aortic stenosis, reduced LV systolic function, and low transvalvular gradient.     

Aortic valve replacement with the Sorin Pericarbon Freedom stentless valve: five-year follow up

BACKGROUND AND AIM OF THE STUDY: Presumed benefits from stentless bioprostheses include larger orifice areas with lower transvalvular gradients, and improved hemodynamic flow characteristics and annular mechanics. Herein are reported the results of a large series of the Sorin Pericarbon Freedom stentless valve implanted in the aortic position. METHODS: Between July 1998 and June 2003, a total of 102 consecutive patients (58 males, 44 females; mean age 71.7+/-7.8 years; range: 28-87 years) requiring aortic valve replacement (AVR), including those undergoing concomitant procedures of coronary artery bypass, mitral valve repair and mini-maze, was recruited. The predominant lesion was aortic stenosis (n = 92; 90.2%); aortic regurgitation (AR) occurred in five patients (4.9%) (including three with endocarditis), and mixed aortic valve disease in five (4.9%). Six patients (5.9%) had undergone previous cardiac surgery. The median preoperative NYHA class was III. Thirsty-six patients (35.3%) underwent AVR alone. The mean valve size was 25 mm (range: 21-29 mm). Sixty-three patients (61.8%) had concomitant coronary artery disease that required a mean of 2.4+/-1.1 bypass grafts; three patients (3.0%) had combined AVR and mitral valve repair. The study end points observed were mortality, valve failure due to degeneration or endocarditis, reoperation, thromboembolism, transvalvular gradients and left ventricular (LV) mass regression. RESULTS: The median follow up for all patients was 31 months (range: 12 months to 5 years). The mean total cross-clamp time was 71.7+/-17.6 min without associated procedures, and 93.9+/-19.7 min with concomitant procedures. Early mortality was 4/102 (3.8%); actuarial survival over five years was 89.2%. Freedom from thromboembolism over five years was 95.9%, from reoperation 100%, and from endocarditis 99.98%. Fifty-seven patients (56.4%) had no AR detected postoperatively, and 34 (33.3%) had trivial or mild AR. A significant decline was observed in indexed LV mass regression within six months of surgery, from 190+/-72 g/m(2) at baseline to 152+/-47 g/m(2) (p = 0.01). CONCLUSION: In an elderly population with a high incidence of coronary artery disease, the Sorin Pericarbon Freedom stentless valve offers excellent hemodynamics, resulting in significant regression of left ventricular hypertrophy, together with acceptable operation times, morbidity and mortality in the medium term.     

Left ventricular remodeling after aortic valve replacement]

The aim of the study was the assessment of left ventricular (LV) systolic function and left ventricular mass following aortic valve replacement (AVR) due to aortic valve stenosis as well as the influence of regression of LV hypertrophy in patients with normal and impaired LV systolic function prior to surgery. 74 patients with severe aortic valve stenosis (29 female, 45 male, mean age 66 +/- 18 years) were divided into 2 groups according to LV ejection fraction (EF): Group 1 with EF > 50% (n = 40); Group 2 with EF < or = 50% (n = 34). Furthermore, patients were differentiated into a group A without (n = 53) and a group B with aortic regurgitation (< or = II degrees, n = 21). All patients were examined by transthoracic echocardiography before and 1 month after surgery. There was a significant decrease of LV enddiastolic and endsystolic volume indices following AVR in group 2 and group B. Patients with preoperatively lower EF (group 2) showed an increase in LV ejection fraction from 39 +/- 10% before AVR to 47 +/- 11% after AVR (p < 0.001), whereas patients with preoperative normal EF (group 1) showed a significant decrease in EF (from 62 +/- 8% to 57 +/- 10%, p < 0.05). Also patients with combined aortic valve disease before AVR had an increase of EF after surgery (from 45 +/- 14% to 56 +/- 14%, p < 0.03). There were significant decreases of interventricular septum thickness and LV posterior wall thickness in group 1 and group A, whereas a significant decrease of LV enddiastolic diameter index was noted only in group B. Improvement of the NYHA functional class could be demonstrated in group 2 from 2.8 +/- 0.7 before to 2.2 +/- 0.6 after AVR, as well as in group B from 2.9 +/- 0.7 before to 1.9 +/- 0.7 after surgery. In conclusion, patients with impaired LV function or combined aortic valve disease showed a significant improvement of left ventricular systolic function after AVR, while patients with normal LV function presented a slight decrease of EF. There was a significant regression of left ventricular muscle mass in all groups independent of the left ventricular functional status.     

Role of inadequate adaptive left ventricular hypertrophy in the genesis of mitral regurgitation in patients with severe aortic stenosis: implications for its prevention

BACKGROUND AND AIM OF THE STUDY: Mitral regurgitation (MR) is frequent in patients with severe calcific aortic stenosis (AS). This complicates not only the clinical course of AS, but also its surgical management. The aim of the present study was to investigate the mechanism of genesis of MR in patients with severe AS. METHODS: The echocardiographic database was searched for subjects with severe AS defined as a calculated (continuity equation) aortic valve area < 0.7 cm2. Patients with previous valve surgery were excluded; thus, the study group comprised 123 patients. RESULTS: Among 123 patients (mean age 75 +/- 10 years) with severe AS, 54 (44%) had no MR, 37 (30%) had mild MR, 20 (16%) had moderate MR, and 12 (10%) had severe MR. Hence, moderate or severe MR was present in approximately 25% of patients. Patients with moderate or severe MR had a larger left ventricular (LV) end-diastolic diameter (5.1 +/- 1.0 versus 4.8 +/- 0.8 cm; p = 0.08), larger LV end-systolic diameter (3.8 +/- 1.2 versus 3.1 +/- 0.8 cm; p = 0.001), lower LV ejection fraction (40 +/- 16 versus 58 +/- 18%; p = 0.0001), higher degree of aortic regurgitation (p = 0.002), larger left atrial diameter (4.7 +/- 0.9 versus 4.1 +/- 0.6 cm; p = 0.001), lower LV free wall thickness (1.1 +/- 0.2 versus 1.3 +/- 0.4 cm; p = 0.05), and lower combined wall thickness (2.4 +/- 0.3 versus 2.7 +/- 0.5 cm; p = 0.02) and relative wall thickness (0.5 +/- 0.1 versus 0.6 +/- 0.1 cm; p = 0.02). Both groups had similar degrees of AS and mitral annular calcification. CONCLUSION: MR in severe AS is associated with a larger LV size and lesser wall thickness, and this may result from failure of adequate adaptive LV hypertrophy necessitated by the pressure overload imposed by AS. This might have important clinical implications in terms of timing of aortic valve replacement before the left ventricle begins to dilate, and also in the choice of pharmacologic therapy that may modulate the adaptive response of the left ventricle.     

The Freedom SOLO valve: superior hemodynamic results with a new stentless pericardial valve for aortic valve replacement

BACKGROUND AND AIM OF THE STUDY: The new Freedom SOLO aortic valve, as a modification of the Pericarbon Freedom stentless valve, requires only one suture line. The study aim was to compare both prostheses with regard to surgical convenience and early postoperative hemodynamics. METHODS: In this case-matched study, 90 patients underwent primary elective isolated or combined aortic valve replacement (AVR) between 2001 and 2004. The Freedom SOLO valve was implanted in 30 patients using a supra-annular, subcoronary technique with one continuous subcoronary suture line (group FS). For comparison, the Pericarbon Freedom valve was implanted in 30 patients using an interrupted suture (group PFI), and in 30 patients using a continuous suture line at the inflow site (group PFC). Patient hemodynamics at discharge were investigated by monitoring echocardiographic peak and mean gradients, and regurgitation. RESULTS: The mean extracorporeal circulation time (75.5+/-22.7 min in FS; 83.7+/-21.0 min in PFC versus 110.9+/-31.4 min in PFI) and cross-clamp time (56.0+/-18.6 min in FS; 62.2+/-16.2 min in PFC versus 87.7 +/-25.4 min in PFI) were significantly shorter with the continuous implantation techniques. Hemodynamics were most favorable for the Freedom SOLO valve as compared to either implantation technique of the Pericarbon Freedom valve (mean gradient 7.4+/-4.6 mmHg in FS versus 10.6+/-6.0 mmHg in PFC and 11.0+/-5.7 mmHg in PFI). There were no paravalvular leakages or transvalvular regurgitations. CONCLUSION: The Freedom SOLO stentless valve is easy to implant and demonstrates superior early postoperative hemodynamics. Due to the reduced cross-clamp time, it also offers an attractive option in isolated and combined AVR.     

Prognosis of asymptomatic elderly patients with aortic stenosis]

To elucidate the prognosis of elderly patients with asymptomatic aortic stenosis (AS) and to assess the timing of aortic valve replacement (AVR), 21 asymptomatic patients (8 men, 13 women, mean age: 75 +/- 8 years (54-89 years)), who had Doppler echocardiographic evidence of a significant aortic pressure gradient of greater than 40 mmHg (mean gradient: 75 +/- 31 mmHg), were followed for 33 +/- 10 months. During the follow-up, there were 4 cardiac events (2 cardiac deaths, 2 late AVRs), and 2 non-cardiac deaths (cerebro-vascular accidents). Among 15 survivors, 13 patients were in NYHA class I--II, and the remaining 2 patients were found to have malignant disease. Compared to the 17 patients without cardiac events, those with cardiac events had significantly larger CTR (58 +/- 6% vs. 53 +/- 3%; p less than 0.01), although there were no significant difference in electrocardiographic LVH, echocardiographic LV mass, and Doppler pressure gradient between the two groups. The prevalence of the development of cardiac symptoms during the follow-up was not high (12%) in patients without cardiac events. Among 4 patients with cardiac events, one patient who was 89 years-old at diagnosis died of heart failure, one patient had fatal myocardial infarction which seemed to be unrelated to AS, and two patients had successful late AVR because of new heart failure. The low incidence of fatal cardiac events in asymptomatic patients with aortic stenosis and the relatively high possibility of developing non-cardiac events in elderly patients indicate that the decision-making for AVR should not be solely based upon the pressure gradient detected by Doppler echocardiography.(ABSTRACT TRUNCATED AT 250 WORDS)     

The influence of prosthesis size and design on exercise dynamics after aortic valve replacement

BACKGROUND AND AIM OF THE STUDY: Residual gradient following aortic valve replacement (AVR) may adversely affect clinical outcome. The size and design of the valve may influence these characteristics. The study aim was to determine the influence of prosthesis physical size and leaflet design on hemodynamic performance after mechanical AVR. METHODS: After AVR, two patient groups with a range of valve sizes were studied. Group 1 patients (n=19) each received a monoleaflet valve; group 2 patients (n=18) each received a bileaflet valve. Transthoracic echocardiography was performed at rest and after graded bicycle ergometry to assess prosthetic valve parameters, including mean and peak transvalvular gradient and effective orifice area (EOA). RESULTS: Transprosthetic gradients (mean and peak) measured at rest, maximum exercise and 3-min recovery were related to indexed geometric orifice area (IGOA) by an exponential decay function, with no significant advantage for either valve design. However, in valve sizes < or =25 mm the bileaflet valves demonstrated lower gradients, both at rest and under exercise conditions (mean gradient during exercise, bileaflet versus monoleaflet 19.9 +/- 7.2 mmHg versus 25.6 +/- 6.3 mmHg, p = 0.01). Similarly, EOAs were larger in the bileaflet group when equivalent GOAs < or =2.5 cm2 were compared (EOA: bileaflet versus monoleaflet 1.51 +/- 0.33 cm2 versus 1.14 +/- 0.26 cm2, p = 0.018). The total work performed correlated with prosthesis diameter (r2 = 0.81, p = 0.037) and was not influenced by valve design. CONCLUSION: The hemodynamic performance of mechanical aortic valves, including transprosthetic gradient and maximum exercise work performed, related principally to the prosthesis physical size. However, within the smaller valve sizes, the bileaflet design appeared to offer hemodynamic advantages.     

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.     

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).     

Left ventricular diastolic dysfunction late after aortic valve replacement in patients with aortic stenosis

Patients with severe aortic stenosis (AS) are known to have increased left ventricular (LV) mass and diastolic dysfunction. It has been suggested that LV mass and diastolic function normalize after aortic valve replacement (AVR). In the present study, change in LV mass index and diastolic function 10 years after AVR for AS was evaluated. Patients who underwent AVR from 1991 to 1993 (n = 57; mean age 67 +/- 8.6 years at AVR, 58% men) were investigated with Doppler echocardiography preoperatively and 2 and 10 years postoperatively. Diastolic function was evaluated by integrating mitral and pulmonary venous flow data. Expected values for each patient, taking age into consideration, were defined using a control group (n = 71; age range 18 to 83 years). Patients were classified into 4 types: normal diastolic function (type A), mild diastolic dysfunction (type B), moderate diastolic dysfunction (type C), and severe diastolic dysfunction (type D). There was a reduction in LV mass index between the preoperative (161 +/- 39 g/m2) and 2-year follow-up (114 +/- 28 g/m2) examinations (p <0.0001), but no further reduction was seen at 10 years (119 +/- 49 g/m2). The percentage of patients with increased LV mass index decreased from 83% preoperatively to 29% at 2-year follow-up (p <0.001). The percentage of patients with moderate to severe LV diastolic dysfunction (types C and D) was unchanged between the preoperative (7%) and 2-year follow-up (13%) examinations (p = 0.27). The percentage of patients increased at 10-year follow-up to 61% (p <0.0001). In conclusion, this reveals the development of moderate to severe diastolic dysfunction 10 years after AVR, despite a reduction in the LV mass index.     

The prognostic value of calcification and impaired valve motion in combined aortic stenosis and coronary artery disease

BACKGROUND AND AIMS OF THE STUDY: Optimal management of patients with coronary artery disease and concomitant aortic valve stenosis remains a subject of controversy. In this retrospective study, an attempt was made to identify criteria indicating rapid progression of aortic valve stenosis in patients with coronary artery disease. METHODS: Between 1990 and 1999, 47 patients underwent aortic valve replacement (AVR) after previous coronary artery bypass grafting (CABG) at the authors' institution. The postoperative data, including cardiac catheterization films, were reviewed. RESULTS: Aortic valve disease, mainly aortic stenosis, showed a rapid rate of progression. During a mean interval between CABG and AVR of 5.9 +/- 2.9 years, the mean peak-to-peak pressure gradient across the aortic valve rose from 16.1 +/- 13.8 to 61.4 +/- 23.9 mmHg in patients where presence of calcification and impaired aortic valve motion was found (66.0% of patients had calcified aortic valves; 72.3% had impaired valve motion) at the time of CABG; whereas in those without calcification and/or impaired leaflet motion a mean of 9.2 +/- 0.8 years elapsed before AVR became necessary. CONCLUSION: If a patient must undergo surgery for coronary artery disease, then AVR should be considered not only on the basis of hemodynamic criteria but also with regard to calcification of the aortic valve and its leaflet motion.     

Effect of coronary bypass and valve structure on outcome in isolated valve replacement for aortic stenosis

Reports differ regarding the effect of concomitant coronary artery bypass grafting (CABG) in patients who undergo aortic valve replacement (AVR) for aortic stenosis (AS), and no reports have described the effect of aortic valve structure in patients who undergo AVR for AS. A total of 871 patients aged 24 to 94 years (mean 70) whose AVR for AS was their first cardiac operation, with or without first concomitant CABG, were included. Patients who underwent mitral valve procedures were excluded. In comparison with the 443 patients (51%) who did not undergo CABG, the 428 (49%) who underwent concomitant CABG were significantly older, were more often male, had lower transvalvular peak systolic pressure gradients and larger valve areas, had lower frequencies of congenitally malformed aortic valves, had lighter valves by weight, had higher frequencies of systemic hypertension, and had longer stays in the hospital after AVR. Early and late (to 10 years) mortality were similar by propensity-adjusted analysis in patients who did and did not undergo concomitant CABG. Congenitally unicuspid or bicuspid valves occurred in approximately 90% of those aged 21 to 50, in nearly 70% in those aged 51 to 70 years, and in just over 30% in those aged 71 to 95 years. Unadjusted and adjusted survival was significantly higher in patients with unicuspid or bicuspid valves compared to those with tricuspid valves. In conclusion, although concomitant CABG had no effect on the adjusted probability of survival, the type of aortic valve (unicuspid or bicuspid vs tricuspid) significantly affected the unadjusted and adjusted probability of survival.     

Stroke-work loss underestimates hemodynamic significance of aortic stenosis in patients with hypertension

BACKGROUND: Stroke-work loss (SWL) represents the amount of energy the left ventricle dissipates as heat because of outflow obstruction. Recent studies suggest that SWL > 25% was the most clinically efficient Doppler measure for predicting hemodynamic significance, symptomatic status, and outcome in patients with aortic stenosis (AS). However, SWL may be affected by systolic blood pressure (SBP). OBJECTIVE: To determine if SWL reliably predicts hemodynamic significance of AS in patients with hypertension. METHODS: We studied 42 consecutive patients with hemodynamically significant AS requiring aortic valve replacement (AVR). Data on demographics, preoperative hemodynamics, and echocardiographic parameters were obtained. SWL was measured using the formula SWL = 100 x mean PG/ (mean PG + SBP), where PG is transaortic pressure gradient. Patients were considered hypertensive if their BP > 140/90 mmHg or if they are on antihypertensive medications. RESULTS: There were 27 males (64%) and mean age was 68 +/- 11 years. Twenty-four patients (57%) were hypertensive. Mean SBP was 134 +/- 24 mmHg, mean transaortic PG 47 +/- 20 mmHg, effective valve orifice area (EOA) by Doppler estimation 0.74 +/- 0.23 cm(2), and SWL 26 +/- 9%. Patients with hypertension had smaller SWL than normotensives (table I). SWL was >25% in 20 (49%) patients, and fewer patients with hypertension have SWL >25% (33% vs 71%, P = 0.019). Of note, patients with SWL < or =25% had significantly higher SBP (145 +/- 21 mmHg vs 122 +/- 22 mmHg, P = 0.02). CONCLUSION: SWL underestimates the hemodynamic significance of aortic stenosis in the majority of patients with hypertension.     

Long-term results with the Biocor-SJM stentless porcine aortic bioprosthesis

BACKGROUND AND AIM OF THE STUDY: The study aim was to update the clinical analysis of hemodynamic performance, structural failure and survival in patients undergoing aortic valve replacement (AVR) with a composite aortic, aldehyde tanned, stentless porcine bioprosthesis. METHODS: Between January 1990 and March 2001, 247 patients underwent AVR with aortic stentless valves. Patient demographic and clinical analysis included age, sex, valve lesion, valve size, pre- and postoperative NYHA class, hospital morbidity, mortality, operative data and duration of hospitalization. RESULTS: Mean patient age was 47.3 years; 71% of patients were males, and 45% had aortic insufficiency. The incidence of rheumatic heart disease requiring surgery was 41.7%. In 23% of patients surgery was indicated due to aortic stented bioprosthetic dysfunction. Preoperatively, 81% of patients were in NYHA classes III and IV. Mean follow up was 5.9+/-2.8 years (range: 1 month to 11.4 years); total follow up was 1,392 patient-years (98% complete). The valve size used was < or =25 mm in 75.3% of patients. The mean intensive care unit stay was 2.6 days; mean hospital stay was 10.7 days. Hospital mortality was 4.0% and late death 6.1%. There were no valve-related deaths. Postoperatively, the mean aortic effective orifice area (EOA) was 1.71 cm2, the mean peak transvalvular gradient 17.1 mmHg, and the mean transvalvular gradient 9.0 mmHg; the left ventricular mass index (g/m2) was 174 and 117 before and after surgery respectively. The rate of leaflet tissue degeneration was 0.9%, and seen as mild by echocardiographic follow up. Actuarial survival at almost 12 years was 91%, and freedom from reoperations was approximately 99%. CONCLUSION: Patients with aortic stentless valves have hemodynamic benefits seen as larger aortic EOA, low transvalvular gradients, satisfactory left ventricular remodeling with significant reduction of left ventricular mass, low complication rate, low reoperation rate, lower leaflet tissue degeneration rate, and no valve-related mortality. A longer follow up is required to confirm these benefits.