Weight gain potential-a neglected entity during valve replacement

Introduction

During valve replacement, appropriate valve size will be chosen based on many factors, neglecting the potential of the patient for gaining weight. We aimed at evaluating the weight gain potential and its effect on hemodynamics in post mitral valve replacement (MVR) patients.

Material and methods

In 118 post-MVR patients, demographic and echocardiographic data at the time of discharge and follow-up were obtained and analyzed. Primary aim of study is to analyze the hemodynamics of patients based on weight gain/loss. Secondary aim is to evaluate the same in patient-prosthesis mismatch (PPM) subgroup and to evaluate the study population for the potential to gain/loss weight.

Results

Among 118 patients, 87 patients (73.7%) gained weight. In 87 weight gained patients, left atrial (LA) size (p = 0.011) and pulmonary artery systolic (PA) pressure (p = 0.028) at follow-up were significantly elevated than the discharge values. Among 53 PPM patients (incidence, 44.9%), 34 patients gained weight and their PA pressure was found to be elevated at follow-up (p = 0.021) whereas weight lost group does not show any significant difference (p = 0.972). Frequency of weight gain was more among patients who weighed < 50 kg preoperatively (28 out of 30) (p = 0.013) and 20 to 30 years age group patients (p = 0.043). No sex predilection was noted (p = 0.149).

Conclusion

In post-MVR patients, weight gain has definitive influence over hemodynamics. In PPM subgroup, weight gained patients had significantly increased PA systolic pressure at follow-up. Young, < 50 kg weighed, and PPM patients should be advised to maintain their weight post MVR for better hemodynamics.

Incidence and predictors of mismatch after mechanical mitral valve replacement

Background

Patient-prosthesis mismatch after mitral valve replacement has an unfavorable postoperative hemodynamic outcome, which underlines the importance of identifying and preventing prosthesis- and patient-related risk factors. This study was conducted to determine the incidence and identify possible predictors of patient-prosthesis mismatch.

Methods

A prospective study was conducted on 715 patients with a mean age of 42 ± 11 years who underwent mechanical mitral valve replacement between 2013 and 2017. The effective orifice area of the prostheses was estimated by the continuity equation, and a mismatch was defined as an effective orifice area index ≤1.2 cm2·m−2. The mean clinical and echocardiographic follow-up was 26.74 ± 11.58 months. Multivariate regression analysis was performed to identify predictors of patient-prosthesis mismatch.

Results

Patient-prosthesis mismatch was detected in 382 (53.4%) patients. A small mechanical prosthesis (<27 mm) was inserted in 54.3%. Mortality during follow-up was 9% (65 patients). Patient-prosthesis mismatch was identified in patients with preoperative rheumatic mitral valve pathology, associated tricuspid regurgitation, higher New York Heart Association class, preoperative atrial fibrillation, mitral stenosis, and small preoperative left ventricular dimensions. Multivariate analysis identified mitral stenosis, preoperative atrial fibrillation, and small postoperative left ventricular end-diastolic dimension as risk factors for patient-prosthesis mismatch.

Conclusion

Patient-prosthesis mismatch is a common sequela after mechanical mitral valve replacement. Identification of predictors of patient-prosthesis mismatch can help so that a preoperative strategy can be implemented to avoid its occurrence.

Bioprosthetic Valve Fracture for Valve-in-Valve Transcatheter Aortic Valve Replacement: Rationale, Patient Selection, Technique, and Outcomes

Patient-prosthesis mismatch (PPM) is common after surgical valve aortic replacement. A significant percentage of patients with a small annulus have moderate to severe PPM. The outcomes for patients with larger effective orifice areas and lower gradients are better than for patients with PPM. With the advent of valve-in-valve TAVR, a degenerated surgical bioprosthesis can be treated with a percutaneous approach. However, the issue of PPM cannot be overcome by simply implanting a new valve. The technique of bioprosthetic valve fracture was therefore developed. This allows for implantation of a fully expanded transcatheter valve and results in a large effective orifice.

Patient prosthesis mismatch and its impact on left ventricular regression following aortic valve replacement in aortic stenosis patients

Introduction

Patient prosthesis mismatch is known to alter post-operative remodeling of left ventricle adversely in aortic stenosis patients. An indexed orifice area of 0.85 is considered as conventional cutoff for patient prosthesis mismatch based on hemodynamic principles. Many patients have smaller annulus and annulus enlargement techniques may be required to avoid this benchmark which complicates the surgery.

Aims and objectives

To determine incidence of patient prosthesis mismatch (PPM) in our population, to assess left ventricle (LV) regression and impact of indexed effective orifice area on LV regression, and to determine a minimum acceptable cut off indexed orifice area that will result in LV regression.

Materials and methods

A single-center retrospective observational study of all patients who underwent aortic valve replacement surgery for severe aortic stenosis between July 2015 and December 2015 was conducted. Patients who underwent concomitant revascularization or other valve surgery were excluded. Data regarding conventional risk factors for PPM, valve type, and indexed orifice area as well as pre-operative and late post-operative LV mass were collected.

Observations

Thirty-seven of the 91 patients satisfied inclusion criteria. All patients had significant regression in LV mass. The incidence of PPM was 68%. Regression of indexed left ventricular mass showed a positive correlation of with indexed effective orifice area of the prosthetic valve. The correlation coefficient is + 0.48 (95% CI 0.18-0.698). Left ventricular mass regression was significantly higher in patients with indexed effective orifice area more than 0.75 (68.89 ± 29 vs 122.55 ± 58.84, p = 0.028). Relative left ventricular regression also was significantly higher in patients with an indexed effective orifice area more than 0.75 (39.53 ± 13.13 vs 49.73 ± 15.56, p = 0.022). There is a positive correlation between left ventricular regression and the reduction in mean gradient achieved by valve replacement. The correlation coefficient was + 0.35 (95% CI 0.03-0.61).

Conclusions

The incidence of PPM was found to be comparable to literature. There is a positive correlation between left ventricular regression and indexed effective orifice area of the prosthetic valve. Left ventricular regression was significantly higher in patients with an indexed effective area more than 0.75. This can be considered as criteria for significant PPM in study population.

Left ventricular outflow obstruction predicts increase in systolic pressure gradients and blood residence time after transcatheter mitral valve replacement

Left ventricular outflow tract (LVOT) obstruction is a relatively common consequence of transcatheter mitral valve replacement (TMVR). Although LVOT obstruction is associated with heart failure and adverse remodelling, its effects upon left ventricular hemodynamics remain poorly characterised. This study uses validated computational models to identify the LVOT obstruction degree that causes significant changes in ventricular hemodynamics after TMVR. Seven TMVR patients underwent personalised flow simulations based on pre-procedural imaging data. Different virtual valve configurations were simulated in each case, for a total of 32 simulations, and the resulting obstruction degree was correlated with pressure gradients and flow residence times. These simulations identified a threshold LVOT obstruction degree of 35%, beyond which significant deterioration of systolic function was observed. The mean increase from baseline (pre-TMVR) in the peak systolic pressure gradient rose from 5.7% to 30.1% above this threshold value. The average blood volume staying inside the ventricle for more than two cycles also increased from 4.4% to 57.5% for obstruction degrees above 35%, while the flow entering and leaving the ventricle within one cycle decreased by 13.9%. These results demonstrate the unique ability of modelling to predict the hemodynamic consequences of TMVR and to assist in the clinical decision-making process.

Prosthesis-patient mismatch after mitral valve replacement: a single-centered retrospective analysis in East China

Background

Prosthesis–patient mismatch (PPM) may affect the clinical outcomes of patients undergoing mitral valve replacement (MVR) surgery. We aimed to investigate the incidence of PPM of the mitral position in our center and analyze the possible predictors of PPM as well as its effect on short-term outcomes.

Methods

We retrospectively examined all consecutive patients with isolated or concomitant MVR at our center from 2013 to 2015. PPM was defined as an indexed effective orifice area (iEOA) of ≤1.2 cm2/m2. After inclusion and exclusion, a total of 1067 patients were analyzed. The baseline information were collected and compared between the two groups. Multivariate logistic regression analysis was conducted to determine the preoperative predictors of PPM as well as the effect of PPM on early mortality.

Results

A total of 1067 patients were included in the study. PPM was detected in 15.9% of the patients while 12 patients (1.12%) met the criteria for severe PPM. Patients with PPM compared to the non-PPM patients had higher age, larger body surface area and were more likely to be male and obese. Logistic regression analysis showed that higher age, larger BSA, bioprosthesis and smaller left ventricle end-diastolic diameter were predictors of PPM. There were no significant differences between the PPM and non-PPM groups regarding post-operative complications. Logistic regression analysis showed that PPM was not a risk factor of short-term mortality (P = 0.654). Also, there were no significant differences regarding short−/mid-term heart function between the PPM and non PPM groups (P = 0.902).

Conclusions

Our results demonstrated that higher age, bioprosthesis, larger BSA and smaller left ventricle size were associated with mitral PPM. However, PPM was not associated with poorer early outcomes after MVR surgery. In eastern of China, the prevalence of mitral valve stenosis is high; therefore, whether the standard PPM criteria are suitable for patients of this district needs to be further verified.

Effect of prosthesis patient mismatch in mitral position on pulmonary hypertension

OBJECTIVES

Pulmonary arterial hypertension (PAH) is associated with poor outcome after mitral valve replacement (MVR). We proposed to evaluate the effect of valve prosthesis patient mismatch (PPM) on pulmonary arterial (PA) pressure following MVR.

METHODS

Five hundred patients who have undergone MVR were studied retrospectively. Postoperative PA systolic pressure (PASP) measured 6 months postoperatively by Doppler echocardiography was compared with preoperative values. PASP ≥ 40 mmHg was defined as PAH. Mitral valve effective orifice area was calculated by the continuity equation and indexed for body surface area. PPM was defined as indexed effective orifice area ≤ 1.2 cm2/m2. A multivariate model was constructed to ascertain the independent determinants of systolic PA pressure. Also, a propensity score model was constructed to overcome the baseline differences between the PPM and no PPM groups.

RESULTS

The incidence of PPM in this study was 37.2%. The average postoperative PASPs were 30.49 and 42.35 mmHg in the no PPM and PPM groups, respectively; (P < 0.001). Regression of PAH in the PPM and no PPM groups was 76.26% and 20.64%, respectively; (P < 0.001). The indexed effective orifice area correlated well with postoperative PASP (r = 0.71). The overall survival and freedom from cardiac death at 10 years were 79.8% and 85.3%; and at 20 years were 66.5% and 74.3%, respectively. Both, overall survival and the freedom from cardiac death were higher in the no PPM group than in the PPM group; (P < 0.001). Propensity score matching analysis yielded 112 pairs of the PPM and no PPM cohorts, which revealed higher overall survival and freedom from cardiac death in the no PPM group; (P = 0.028 and 0.012, respectively).

CONCLUSIONS

Mitral PPM is an independent predictor of persistent PAH after MVR along with associated morbidity and reduced survival.

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

AIMS

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

METHODS AND RESULTS

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

CONCLUSION

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

Does stringent restrictive annuloplasty for functional mitral regurgitation cause functional mitral stenosis and pulmonary hypertension?

BACKGROUND

It remains controversial whether restrictive mitral annuloplasty (RMA) for functional mitral regurgitation (MR) can induce functional mitral stenosis (MS) that may cause postoperative residual pulmonary hypertension (PH).

METHODS AND RESULTS

One hundred eight patients with left ventricular (LV) dysfunction and severe MR underwent RMA with stringent downsizing of the mitral annulus. Systolic pulmonary artery pressure (PAP) and mitral valve performance variables were determined by Doppler echocardiography prospectively and 1 month after RMA. Fifty-eight patients underwent postoperative hemodynamic measurements. Postoperative echocardiography showed a mean pressure half-time of 92 ± 14 ms, a transmitral mean gradient of 2.9 ± 1.1 mm Hg, and a mitral valve effective orifice area of 2.4 ± 0.4 cm(2), consistent with functional MS. Doppler-derived systolic PAP was 32 ± 8 mm Hg, which correlated weakly with the transmitral mean gradient (ρ=0.23, P=0.02). Postoperative cardiac catheterization also showed significant improvements in LV volume and systolic function, pulmonary capillary wedge pressure, cardiac index, and systolic PAP; the latter was associated with LV end-diastolic pressure [standardized partial regression coefficient (SPRC)=0.51], pulmonary vascular resistance (SPRC=0.47), cardiac index (SPRC=0.37), and transmitral pressure gradient (SPRC=0.20). In a multivariate Cox proportional hazard model, postoperative PH (systolic PAP >40 mm Hg), but not mitral valve performance variables, was strongly associated with adverse cardiac events.

CONCLUSIONS

RMA for functional MR resulted in varying degrees of functional MS. However, our data were more consistent with the residual PH being caused by LV dysfunction and pulmonary vascular disease than by the functional MS. The residual PH, not functional MS, was the major predictor of post-RMA adverse cardiac events.

Hemodynamic impact of mitral prosthesis-patient mismatch on pulmonary hypertension: an in silico study

Recent clinical studies reported that prosthesis-patient mismatch (PPM) becomes clinically relevant when the effective orifice area (EOA) indexed by the body surface area (iEOA) is <1.2-1.25 cm(2)/m(2). To examine the effect of PPM on transmitral pressure gradient and left atrial (LA) and pulmonary arterial (PA) pressures and to validate the PPM cutoff values, we used a lumped model to compute instantaneous pressures, volumes, and flows into the left-sided heart and the pulmonary and systemic circulations. We simulated hemodynamic conditions at low cardiac output, at rest, and at three levels of exercise. The iEOA was varied from 0.44 to 1.67 cm(2)/m(2). We normalized the mean pressure gradient by the square of mean mitral flow indexed by the body surface area to determine at which cutoff values of iEOA the impact of PPM becomes hemodynamically significant. In vivo data were used to validate the numerical study, which shows that small values of iEOA (severe PPM) induce high PA pressure (residual PA hypertension) and contribute to its nonnormalization following a valve replacement, providing a justification for implementation of operative strategies to prevent PPM. Furthermore, we emphasize the major impact of pulmonary resistance and compliance on PA pressure. The model suggests also that the cutoff iEOA that should be used to define PPM at rest in the mitral position is approximately 1.16 cm(2)/m(2). At higher levels of exercise, the threshold for iEOA is rather close to 1.5 cm(2)/m(2). Severe PPM should be considered when iEOA is <0.94 cm(2)/m(2) at rest.

Beating Heart Mitral Valve Replacement with a Bovine Pericardial Bioprosthesis for Treatment of Mitral Valve Dysplasia in a Bull Terrier

OBJECTIVES

To describe an open, beating heart surgical technique and use of a bovine pericardial prosthetic valve for mitral valve replacement (MVR) in the dog.

STUDY DESIGN

Clinical case report.

ANIMALS

Male Bull Terrier (17-month-old, 26 kg) with mitral valve dysplasia and severe regurgitation.

METHODS

A bovine pericardial bioprosthesis was used to replace the mitral valve using an open beating heart surgical technique and cardiopulmonary bypass.

RESULTS

Successful MVR was achieved using a beating heart technique. Mitral regurgitation resolved and cardiac performances improved (left ventricular end-diastolic diameter decreased from 57.6 to 48.7 mm, and left atrium/aorta ratio returned to almost normal, from 1.62 to 1.19). Cardiopulmonary by-pass time and total surgical duration were decreased compared with standard cardioplegic techniques. Surgical recovery was uneventful and on echocardiography 6 months later valve function was excellent.

CONCLUSION

Considering the technique advantages (no cardiac arrest, ischemic reperfusion injury, and hypothermia, or the need for aortic dissection and cannulation for administration of cardioplegic solution), short-term mortality and morbidity may be reduced compared with standard cardioplegic techniques.

CLINICAL RELEVANCE

Based on experience in this dog, beating heart mitral valvular replacement is a seemingly safe and viable option for the dog and bovine pericardial prosthesis may provide better long-term survival than mechanical prostheses.

Impact of Prosthesis-Patient Mismatch on Survival After Mitral Valve Replacement

Background— We recently reported that valve prosthesis-patient mismatch (PPM) is associated with persisting pulmonary hypertension after mitral valve replacement. Thus, the objective of this study was to evaluate the impact of PPM on mortality in patients undergoing mitral valve replacement.

Methods and Results— The indexed valve effective orifice area was estimated for each type and size of prosthesis being implanted in 929 consecutive patients and used to define PPM as not clinically significant if >1.2 cm 2 /m 2 , as moderate if >0.9 and ≤1.2 cm 2 /m 2 , and as severe if ≤0.9 cm 2 /m 2 . Moderate PPM was present in 69% of patients; severe PPM was seen in 9%. For patients with severe PPM, 6-year survival (74±5%) and 12-year survival (63±7%) were significantly less than for patients with moderate PPM (84±1% and 76±2%; P =0.027) or nonsignificant PPM (90±2% and 82±4%; P =0.002). On multivariate analysis, severe PPM was associated with higher mortality (hazard ratio, 3.2; 95% confidence interval, 1.5 to 6.8; P =0.003).

Conclusions— Severe PPM is an independent predictor of mortality after mitral valve replacement. As opposed to other independent risk factors, PPM may be avoided or its severity may be reduced with the use of a prospective strategy at the time of operation. For patients identified as being at risk for severe PPM, every effort should be made to implant a prosthesis with a larger effective orifice area.

Impact of Prosthesis-Patient Mismatch on Cardiac Events and Midterm Mortality After Aortic Valve Replacement in Patients With Pure Aortic Stenosis

Background— Prosthesis-patient mismatch (PPM) occurs when the effective orifice area (EOA) of the prosthesis being implanted is too small in relation to body size, thus causing abnormally high transvalvular pressure gradients. The objective of this study was to examine the midterm impact of PPM on overall mortality and cardiac events after aortic valve replacement in patients with pure aortic stenosis.

Methods and Results— The indexed EOA (EOAi) was estimated for each type and size of prosthesis being implanted in 315 consecutive patients with pure aortic stenosis. PPM was defined as an EOAi ≤0.80 cm 2 /m 2 and was correlated with overall mortality and cardiac events. PPM was present in 47% of patients. The 5-year overall survival and cardiac event-free survival were 82±3% and 75±4%, respectively, in patients with PPM compared with 93±3% and 87±4% in patients with no PPM ( P ≤0.01). In multivariate analysis, PPM was associated with a 4.2-fold (95% CI, 1.6 to 11.3) increase in the risk of overall mortality and 3.2-fold (95% CI, 1.5 to 6.8) increase in the risk of cardiac events. The other independent risk factors were history of heart failure, NHYA class III-IV, severe left ventricular hypertrophy, and absence of normal sinus rhythm before operation.

Conclusions— PPM is an independent predictor of cardiac events and midterm mortality in patients with pure aortic stenosis undergoing aortic valve replacement. As opposed to other risk factors, PPM may be avoided or its severity may be reduced with the use of a preventive strategy at the time of operation.

Hemodynamic Comparison of Bioprostheses for Complete Supra-Annular Position in Patients With Small Aortic Annulus

OBJECTIVES

The present study evaluates complete supra-annular bioprostheses in patients with an aortic annulus of 18 to 23 mm in diameter.

BACKGROUND

Aortic valve replacement in patients with small aortic annulus using stented bioprostheses is often associated with unsatisfactory hemodynamic results and high incidence of patient-prosthesis mismatch.

METHODS

Between February 2000 and January 2004, 156 patients with aortic valve disease and an aortic annulus of 18 to 23 mm in diameter received the stented bovine Soprano (Sorin Biomedica Cardio, Saluggia, Italy) (n = 18), Perimount (Edwards Lifesciences, Irvine, California) (n = 52), Perimount Magna (Edwards Lifesciences) (n = 42), or the stented porcine Mosaic (Medtronic Inc., Minneapolis, Minnesota) (n = 44) bioprostheses. Intraoperatively, the surgeon measured the aortic annulus diameter by inserting a hegar dilator. Thus, postoperative hemodynamic results could be referred to the patient's aortic annulus diameter instead of referring the results to the labeled valve size. This allows for objective comparisons between different valve types.

RESULTS

There was no significant difference in hemodynamic results between the different valve types in patients with an aortic annulus 18 to 20 mm. In patients with an annulus 21 to 23 mm, the Magna was significantly superior to the other investigated devices in mean pressure gradient, effective orifice area, and incidence of patient-prosthesis mismatch. There was no significant difference between the complete supra-annular bioprostheses Mosaic and Soprano and the intra-supra-annular Perimount valve.

CONCLUSIONS

In patients with an aortic annulus of 18 to 20 mm in diameter, hemodynamic performance is independent of the implanted stented valve type and the annular position. Root enlargement or stentless valves may be beneficial alternatives. Patients with annulus diameter 21 to 23 mm benefit from the Magna in complete supra-annular position leading to superior hemodynamic results.

Impact of valve prosthesis-patient mismatch on pulmonary arterial pressure after mitral valve replacement

OBJECTIVES

We sought to determine the impact of valve prosthesis-patient mismatch (PPM) on pulmonary arterial (PA) pressure after mitral valve replacement (MVR).

BACKGROUND

Pulmonary arterial hypertension is a serious complication of mitral valve disease, and it is a major risk factor for poor outcome after MVR. We hypothesized that valve PPM might be a determinant of PA hypertension after MVR.

METHODS

Systolic PA pressure was measured by Doppler echocardiography in 56 patients with normally functioning mitral prosthetic valves. Mitral valve effective orifice area (EOA) was determined by the continuity equation and indexed for body surface area.

RESULTS

Thirty patients (54%) had PA hypertension defined as systolic PA pressure >40 mm Hg, whereas 40 patients (71%) had PPM defined as an indexed EOA < or =1.2 cm(2)/m(2). There was a significant correlation (r = 0.64) between systolic PA pressure and indexed EOA. The average systolic PA pressure and prevalence of PA hypertension were 34 +/- 8 mm Hg and 19% in patients with no PPM versus 46 +/- 8 mm Hg and 68% in patients with PPM (p < 0.001). In multivariate analysis, the indexed EOA was by far the strongest predictor of systolic PA pressure.

CONCLUSIONS

Persistent PA hypertension is frequent after MVR and strongly associated with the presence of PPM. The clinical implications of these findings are important given that PPM can largely be avoided by using a simple prospective strategy at the time of operation.

Impact of Valve Prosthesis-Patient Mismatch on Left Ventricular Mass Regression Following Aortic Valve Replacement

BACKGROUND

Valve prosthesis-patient mismatch is a frequent problem in patients undergoing aortic valve replacement and its main hemodynamic consequence is to generate high transvalvular gradients through normally functioning prosthetic valves. The persistence of high gradients may hinder or delay the regression of left ventricular hypertrophy after aortic valve replacement.

METHODS

The aim of the study was to determine the impact of prosthesis-patient mismatch on the postoperative regression of left ventricular mass. Left ventricular mass was measured by Doppler echocardiography in 109 patients undergoing aortic valve replacement with a single type of bioprosthesis (Carpentier-Edwards Perimount) for pure aortic stenosis. Prosthesis-patient mismatch was defined as a projected indexed effective orifice area less than 0.90 cm2/m2. On this basis, 58/109 (53.2%) patients had prosthesis-patient mismatch.

RESULTS

There was a good correlation (r = 0.61, p < 0.001) between the postoperative mean transprosthetic gradient and the projected indexed effective orifice area. The absolute and relative left ventricular mass regression was significantly (p = 0.002 and p = 0.01, respectively) lower in patients with prosthesis-patient mismatch (-48 +/- 47 g, -17% +/- 16%) compared to those with no prosthesis-patient mismatch (-77 +/- 49 g, -24% +/- 14%). In multivariate analysis, a larger projected indexed effective orifice area, female gender and a higher preoperative left ventricular mass are independent predictors of greater left ventricular mass regression.

CONCLUSIONS

This study shows that in patients with pure aortic stenosis prosthesis-patient mismatch is associated with lesser regression of left ventricular hypertrophy after aortic valve replacement. These findings may have important clinical implications given that prosthesis-patient mismatch is frequent in these patients.

Experience of the small size (25 mm) Sorin Bicarbon bileaflet prosthetic valve in patients with small mitral annuli

BACKGROUND

Currently, there is a tendency to use large-size prosthetic valves in mitral position in order to achieve better hemodynamic performance. We aimed to evaluate hemodynamic performance of 25 mm prosthetic valves in mitral position.

METHODS

Between August 1998 and May 2000, a total of 40 patients, 34 women and 6 men (mean age 42 +/- 12 years), underwent mitral valve replacement with 25 mm bileaflet mechanical valve. Preoperative functional capacity was New York Heart Association classes III and IV in 31 patients. Major indication for surgery was severe mitral stenosis in all patients.

RESULTS

Total hospital mortality was 5% (two patients). Mean follow-up period was 14.7 +/- 4.9 months (2 to 23 months). No thromboembolic event, paravalvular leak, mechanical failure, endocarditis were observed during the follow-up period. Postoperatively 92.5% of the patients were in the functional capacity of New York Heart Association class I. Postoperative echocardiographic observations have given an average pulmonary artery pressure of 29 +/- 2 mmHg, effective orifice area as 2.95 +/- 0.1 cm2, and mean prosthetic gradient as 6.5 +/- 2.7 mmHg.

CONCLUSION

In short- and mid-term, small-size (25 mm) Sorin mechanical mitral valves had excellent hemodynamic performance in patients with severe mitral stenosis, moderate or serious pulmonary hypertension, and small mitral annuli, whose body surface area was smaller than 1.6 m2.

Impact of valve prosthesis-patient mismatch on short-term mortality after aortic valve replacement

BACKGROUND

The prosthesis used for aortic valve replacement (AVR) can be too small in relation to body size, thus causing valve prosthesis-patient mismatch (PPM) and abnormally high transvalvular pressure gradients. This study examined if there is a relation between PPM and short-term mortality after operation.

METHODS AND RESULTS

The indexed valve effective orifice area (EOA) was estimated for each type and size of prosthesis being implanted in 1266 consecutive patients and used to define PPM as not clinically significant if >0.85 cm2/m2, as moderate if >0.65 cm2/m2 and <or=0.85 cm2/m2, and as severe if <or=0.65 cm2/m2; it was correlated with 30-day mortality and compared with other relevant variables. Moderate or severe PPM was present in 38% of patients. Thirty-day mortality was 4.6% (58/1266 patients) and the strongest independent predictors in multivariate analysis were left ventricular ejection fraction <40% (P=0.007), infectious endocarditis (P=0.002), emergent/salvage operation (P=0.002), cardiopulmonary bypass time >120 minutes (P=0.001), and PPM (P=0.003). Relative risk of mortality was increased 2.1-fold (95% confidence interval, 1.2 to 3.7) in patients with moderate PPM and 11.4-fold (4.4 to 29.5) in those with severe PPM. Moreover, risk of mortality for every category of PPM was higher in patients with a left ventricular ejection fraction <40% as compared with >or=40% (nonsignificant PPM, 2.7 versus 1.0; moderate PPM, 7.1 versus 1.8; severe PPM, 77.1 versus 11.3).

CONCLUSIONS

PPM is a strong and independent predictor of short-term mortality among patients undergoing AVR, and its impact is related both to its degree of severity and the status of left ventricular function. In contrast to other risk factors, moderate-severe PPM can be largely avoided with the use of a prospective strategy at the time of operation.

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.

Left ventricular architecture after valve replacement due to critical aortic stenosis: an approach to dis-/qualify the myth of valve prosthesis-patient mismatch?

OBJECTIVES

Left ventricular hypertrophy in patients with critical aortic stenosis (AS) is an adaptive process that compensates for high intracavitary pressure and reduces systolic wall stress followed by an increase in myocardial masses. In the present prospective clinical trial, we investigated long-term compensatory changes in left ventricular geometry and function after aortic valve replacement using mechanical bileaflet prostheses with the main emphasis on the small-sized aortic annulus and valve prosthesis-patient mismatch.

METHODS

A total of 58 patients with critical AS were assigned to the following groups according to the predictive value of prosthetic valve area index (VAI): group EXMIS: 29 patients (VAI < or =0.99), expected mismatch; group NOMIS: 29 patients (VAI < or =0.99), no mismatch. At controls T(0) (before operation/operation (OP), T(1) and T(2) (4 and 20 months after OP) the left ventricular geometry was recorded by means of Imatron electron beam tomography and the transprosthetic velocities were measured by echocardiography.

RESULTS

Statistical analysis showed a consistent reduction in the absolute (P=0.04) and indexed (P=0.04) left ventricular myocardial mass for both cohorts; furthermore, there was a significant difference between EXMIS and NOMIS patients concerning the factors, time and mass reduction (P=0.005), because of distinct baselines. A logistic regression report revealed preoperative cardiac output, absolute left ventricular myocardial mass, perfusion, body surface area and the native valve orifice area as predicting coefficients and factors for a minimum mass reduction of 25%. We explain a mathematical formula that turned out to be the most sensitive for correctly classified factors.

CONCLUSIONS

The left ventricular geometry and transprosthetic velocities resulted in the same postoperative recovery for both EXMIS and NOMIS patients. The presented data showed that valve prosthesis-patient mismatch had no influence in several stepwise logistic regression models. We conclude that modern mechanical bileaflet prostheses allow both acceptable hemodynamics and recovery of left ventricular hypertrophy, even in small aortic annuli.

Standard 19mm St Jude aortic valves in patients with body surface less than 1.7m2

Although new models of bileaflet valves with improved orifice have been devised, aortic valve replacement with 19mm prostheses still raises concerns about long term effects of residual transprosthetic gradient.

We reviewed our experience with 19 mm standard model St Jude prostheses in 68 patients operated on between January 1983 and December 1995. Clinical late assessment was performed to evaluate the incidence of valve related complications. Postoperative echocardiography was performed to evaluate hemodynamic performance of the prostheses.

Mean body surface area was 1.66±0.14m2. Late postoperative peak gradient was 53.85±7.16 mmHg; mean gradient was 34.80±5.55 mm Hg; effective orifice area was 1.93±0.05 cm2. Thirteen-year actuarial survival has been 90.89 ± 0.6%; thirteen-year freedom from embolism 89.41 ± 0.7% and freedom from hemorrhage 98.25 ± 0.02%. No case of prosthetic endocarditis, thrombosis, or reoperation was observed during follow-up.

Survival advantage of stentless aortic bioprostheses

BACKGROUND

Bioprostheses (BPs) are used to avoid anticoagulation after aortic valve replacement (AVR) in patients over 65 years of age. Stentless BPs offer established hemodynamic benefits. We sought to determine whether these advantages translate into improved survival.

METHODS

Between 1993 and 1997, follow-up data (for Food and Drug Administration submission) were collected prospectively for 160 consecutive, unselected hospital survivors who received the Freestyle valve (FS). Equivalent data were collected for 247 Carpentier-Edwards (CE) porcine xenograft patients. Detailed comparative statistical analysis was used to compare events and survival between the groups. Follow-up was 100% complete for the FS (5.2 years maximum; mean 3.2+/-1.0 years) group and 98% (7.2 years maximum; mean 3.8+/-2.0 years) for CE.

RESULTS

The groups were well matched in age (FS, 73+/-6 years; CE, 74+/-6 years), gender (FS, 58% male; CE, 62% male), ventricular function, and number of patients requiring coronary grafts (FS, 41%; CE, 37%). Actuarial survival at 5 years was 84% for FS versus 69% for CE (p = 0.023 Kaplan Meier, p = 0.009 Cox). Annual mortality rates were 3.6% for FS versus 7.1% for CE (p = 0.001). Thromboembolic rate was 0.8% per year for FS and 2.4% for CE (p = 0.024) without a difference in cardiac rhythm. Incidence of nonstructural dysfunction (paravalvular leak) was 0.2% for FS versus 1.3% for CE (p = 0.020).

CONCLUSIONS

By 5 years, the stentless valve patients had improved survival and reduced adverse events. Though differences in durability are yet to be proved, our findings support the use of stentless bioprostheses in this age group.

Assessment of aortic valve stenosis severity: A new index based on the energy loss concept

BACKGROUND

Fluid energy loss across stenotic aortic valves is influenced by factors other than the valve effective orifice area (EOA). We propose a new index that will provide a more accurate estimate of this energy loss.

METHODS AND RESULTS

An experimental model was designed to measure EOA and energy loss in 2 fixed stenoses and 7 bioprosthetic valves for different flow rates and 2 different aortic sizes (25 and 38 mm). The results showed that the relationship between EOA and energy loss is influenced by both flow rate and aortic cross-sectional area (A(A)) and that the energy loss is systematically higher (15+/-2%) in the large aorta. The coefficient (EOAxA(A))/(A(A)-EOA) accurately predicted the energy loss in all situations (r(2)=0.98). This coefficient is more closely related to the increase in left ventricular workload than EOA. To account for varying flow rates, the coefficient was indexed for body surface area in a retrospective study of 138 patients with moderate or severe aortic stenosis. The energy loss index measured by Doppler echocardiography was superior to the EOA in predicting the end points, which were defined as death or aortic valve replacement. An energy loss index </=0.52 cm(2)/m(2) was the best predictor of adverse outcomes (positive predictive value of 67%).

CONCLUSIONS

This new energy loss index has the potential to reflect the severity of aortic stenosis better than EOA. Further prospective studies are necessary to establish the relevance of this index in terms of clinical outcomes.

Hemodynamic performance of four mechanical bileaflet prosthetic valves in the mitral position: an echocardiographic study

OBJECTIVES

The CarboMedics, Duromedics, Sorin Bicarbon and the St. Jude Medical valves are bileaflet mechanical prostheses of modern but different design. Choosing a valve with the best hemodynamic profile is of clinical importance in patients with small ventricles and a small mitral annulus.

METHODS

The hemodynamic performance of these valves in the mitral position was compared in 76 asymptomatic, ambulatory patients with normally functioning prosthesis and left ventricle, using Doppler echocardiography. Of the 76 patients studied, 22 had the CarboMedics, 16 had the Duromedics, 17 had the Sorin Bicarbon and 21 had the St. Jude prosthesis. The patients ages ranged from 18 to 81 years. There were 44 women and 32 men. The time from implantation to echocardiographic study ranged from 1 to 55 months.

RESULTS

The echocardiographic study was performed earlier after surgery in the Sorin Bicarbon group. There was no significant difference in women/man ratio, incidence of atrial fibrillation, left ventricular or left atrial diameters between the four groups. The mean prosthesis size was significantly smaller for Sorin Bicarbon and Duromedics valves compared to the CarboMedics and the St. Jude valves (mean+/-SD, 27.2+/-1.3, 27.1+/-1.1 and 30.0+/-1.9 and 30.0+/-2.7 mm, respectively, P<0.001). Despite its smaller size the Sorin Bicarbon valve had significantly larger effective valve area by Doppler compared to the CarboMedics valve (290+/-40 vs 250+/-60 mm2, respectively, P=0.014). The ratio of effective valve area to prosthesis size was significantly larger for the Sorin Bicarbon valve when compared with any other type of prosthesis.

CONCLUSIONS

(1) The Sorin Bicarbon bileaflet valve offered the best hemodynamic results that may be explained by the valve's large leaflet opening angle and small thickness of the leaflets. (2) Since the Sorin Bicarbon is the newest bileaflet valve, durability of this valve remains uncertain.

Hemodynamic features of the freestyle aortic bioprosthesis compared with stented bioprosthesis

BACKGROUND

The Freestyle prosthesis is a new stentless aortic bioprosthesis. Anticipated benefits are improved hemodynamics and increased longevity.

METHODS

Doppler echocardiograms were performed early and at 3 to 6 months, 1 year, and 2 years after operation in 157 patients (69 men, 88 women, aged 48 to 85 years) with this prosthesis, and results were compared with hemodynamic data in patients with Intact and Mosaic stented bioprostheses.

RESULTS

Distinctive features of the prosthesis compared with stented prostheses are (1) an increase in effective orifice area (+0.15+/-0.26 cm2; p < 0.05) and a decrease in mean gradient (-3.5+/-4.0 mm Hg; p < 0.001) during the first 3 to 6 months postoperatively and stabilization thereafter; (2) a markedly lower mean gradient at 1 year after operation (average, 6+/-4 mm Hg) than in stented prostheses (Intact, 22+/-8 mm Hg; Mosaic, 12+/-6 mm Hg); (3) in contrast to stented prostheses, in vivo effective orifice areas much lower (-0.91+/-0.35 cm2) than those calculated in vitro; (4) as in stented prostheses, the indexed effective orifice area (cm2/m2) is the best predictor (r = 0.77 at 1 year) of the mean gradient after operation; and (5) similar incidence of aortic regurgitation (trivial or mild, 34% versus 29% in Intact).

CONCLUSIONS

The hemodynamics of the Freestyle are very satisfactory and represent a marked improvement in comparison to stented prosthesis.

Dobutamine Stress Test to Evaluate Different Sizes of Prosthetic Aortic Valves

Dobutamine stress testing and Doppler echocardiography were used to assess hemodynamics in 27 patients aged 16 to 54 years with various sizes and types of aortic valve prosthesis. All patients underwent a symptom-limited treadmill exercise test within two days of the dobutamine test. There was no significant difference in ejection fractions and transvalvular gradients at rest and during dobutamine stress between St. Jude Medical, Medtronic-Hall, and Carbomedics valves. Exercise duration did not differ significantly among the different types of valve. When patients were classified by their underlying lesion, those with aortic stenosis and those with aortic insufficiency had similar ejection fractions and transvalvular gradients at rest and during dobutamine stress. The mean and peak transvalvular gradients at rest and during dobutamine stress were significantly different in patients with different valve sizes but the extent of the increase in gradients during stress was not significant. Linear regression analysis revealed that both peak and mean gradients during dobutamine stress could be predicted by the resting gradients. There was a negative correlation between valve size and gradients at rest and during stress, while there was a significant correlation between exercise duration and valve size. Dobutamine stress echocardiography was useful for studying hemodynamics in patients with aortic valve prostheses and the findings show that valvular size was the main determinant of exercise capacity.

Clinical and hemodynamic comparison of the Medtronic Freestyle and Toronto SPV stentless valves

The excellent hemodynamics of stentless valves have been observed by numerous investigators. With the recent release of the Toronto SPV (stentless porcine valve) and the Medtronic Freestyle stentless valves in North America, it is appropriate to now compare the clinical and hemodynamic performance of these devices. We analyzed the results of 995 patients who underwent aortic valve replacement (AVR) with either of the two valves; in all cases a subcoronary implant technique was used. There were important differences in the preoperative characteristics for the two groups: Medtronic Freestyle patients were notably older than the Toronto SPV patients (70.7+/-8.6 vs 61.8+/-11.1 years, p < 0.001) and were markedly more symptomatic (p < 0.0001). In the Toronto SPV group, most patients had New York Heart Association (NYHA) Class II (41.5%) or Class III (44.7%) symptoms preoperatively, while in the Freestyle group, 61.5% were in Class III and 12.5% were in Class IV. There were no notable differences in mortality or morbidity for the two groups. Both devices demonstrated a meaningful decrease in mean gradient and a corresponding increase in effective orifice area (EOA). Furthermore, the indexed EOA (EOA/body surface area [BSA]) was > 1cm2/m2 for all valves indicating there was no patient-prosthetic mismatch. There was a meaningful decrease in left ventricular (LV) mass as well as LV mass index (LVMI) for both devices up to 3 years postoperatively. Our data indicate that there were no differences in clinical outcome or hemodynamic performance of these two valves. Both devices offer excellent results with normalization of LV function.

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.

New evolution in mitral physiology and surgery: mitral stentless pericardial valve

The human adult mitral valve, with a mean diastolic area of up to 7.6 cm2, excess leaflet surface area for coaptation in systole, mitral annulus-papillary muscle continuity, and systolic constriction of the posterior left ventricular wall around the mitral annulus functions in concert with other components of the left side of the heart. Mitral valve replacement with an artificial valve that interferes with the normal physiology could account for less than adequate late results. A stentless biologic mitral valve substitute has been designed, constructed, and tested. The size of the valve is selected according to the circumference of the excised valve within certain limits. The valve is manufactured of two square or trapezoidal pieces of selected stabilized human autologous or bovine pericardium. The pericardial pieces are sutured together by their lateral margins, thus creating a frusto-conical valvular body. The upper circumference of the valvular body is sutured at the mitral annulus and the lower margin with the new chordae is attached by suture at each papillary muscle. In vitro testing of six stentless bovine pericardial valves in a Rowan-Ash fatigue tester at 1,200 cycles/min revealed a durability of more than 320 million cycles. Clinical use of described technique initiated in 1989 was performed in 18 patients by one surgeon (30 patients in the same institution). The mean valve size was 29 mm circularized diameter. There was no mortality in this group of patients up to 70 months of follow-up. Valve competence was obtained in every case by adequate sizing of the valve.(ABSTRACT TRUNCATED AT 250 WORDS)