Myocardial structure as a determinant of pre- and postoperative ventricular function and long-term prognosis after valve replacement for aortic stenosis

Pressure Overload Activates DNA-Damage Response in Cardiac Stromal Cells: A Novel Mechanism Behind Heart Failure With Preserved Ejection Fraction?

Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous syndrome characterized by impaired left ventricular (LV) diastolic function, with normal LV ejection fraction. Aortic valve stenosis can cause an HFpEF-like syndrome by inducing sustained pressure overload (PO) and cardiac remodeling, as cardiomyocyte (CM) hypertrophy and fibrotic matrix deposition. Recently, in vivo studies linked PO maladaptive myocardial changes and DNA damage response (DDR) activation: DDR-persistent activation contributes to mouse CM hypertrophy and inflammation, promoting tissue remodeling, and HF. Despite the wide acknowledgment of the pivotal role of the stromal compartment in the fibrotic response to PO, the possible effects of DDR-persistent activation in cardiac stromal cell (C-MSC) are still unknown. Finally, this novel mechanism was not verified in human samples. This study aims to unravel the effects of PO-induced DDR on human C-MSC phenotypes. Human LV septum samples collected from severe aortic stenosis with HFpEF-like syndrome patients undergoing aortic valve surgery and healthy controls (HCs) were used both for histological tissue analyses and C-MSC isolation. PO-induced mechanical stimuli were simulated in vitro by cyclic unidirectional stretch. Interestingly, HFpEF tissue samples revealed DNA damage both in CM and C-MSC. DDR-activation markers γH2AX, pCHK1, and pCHK2 were expressed at higher levels in HFpEF total tissue than in HC. Primary C-MSC isolated from HFpEF and HC subjects and expanded in vitro confirmed the increased γH2AX and phosphorylated checkpoint protein expression, suggesting a persistent DDR response, in parallel with a higher expression of pro-fibrotic and pro-inflammatory factors respect to HC cells, hinting to a DDR-driven remodeling of HFpEF C-MSC. Pressure overload was simulated in vitro, and persistent activation of the CHK1 axis was induced in response to in vitro mechanical stretching, which also increased C-MSC secreted pro-inflammatory and pro-fibrotic molecules. Finally, fibrosis markers were reverted by the treatment with a CHK1/ATR pathway inhibitor, confirming a cause-effect relationship. In conclusion we demonstrated that, in severe aortic stenosis with HFpEF-like syndrome patients, PO induces DDR-persistent activation not only in CM but also in C-MSC. In C-MSC, DDR activation leads to inflammation and fibrosis, which can be prevented by specific DDR targeting.

Prosthesis-patient mismatch - what cardiac anesthesiologists need to know?

Prosthesis-patient Mismatch (PPM) is not uncommon with an incidence reported up to 70% after aortic valve (AV) replacement. Severe forms of PPM are less common (up to 20%); PPM can lead to increased short- and long-term morbidity and mortality. It is important to discriminate PPM from other forms of prosthetic valve dysfunction. Sometimes, prosthetic valve degenerative disease may coexist with PPM. Echocardiography plays an important role in the prevention and diagnosis of PPM. Preemptive strategies to prevent PPM include insertion of newer generation prosthetic valves with better hemodynamic characteristics, stentless prosthesis, aortic root enlargement to insert a larger prosthesis, aortic homograft, and transcutaneous AV implantation. We present an illustrative case and review the literature on PPM pertinent to anesthesiologists.

Molecular Mechanisms of Right Ventricular Failure

An abundance of data has provided insight into the mechanisms underlying the development of left ventricular (LV) hypertrophy and its progression to LV failure. In contrast, there is minimal data on the adaptation of the right ventricle (RV) to pressure and volume overload and the transition to RV failure. This is a critical clinical question, because the RV is uniquely at risk in many patients with repaired or palliated congenital heart disease and in those with pulmonary hypertension. Standard heart failure therapies have failed to improve function or survival in these patients, suggesting a divergence in the molecular mechanisms of RV versus LV failure. Although, on the cellular level, the remodeling responses of the RV and LV to pressure overload are largely similar, there are several key differences: the stressed RV is more susceptible to oxidative stress, has a reduced angiogenic response, and is more likely to activate cell death pathways than the stressed LV. Together, these differences could explain the more rapid progression of the RV to failure versus the LV. This review will highlight known molecular differences between the RV and LV responses to hemodynamic stress, the unique stressors on the RV associated with congenital heart disease, and the need to better understand these molecular mechanisms if we are to develop RV-specific heart failure therapeutics.

Relation of Left Ventricular Mass to Prognosis in Initially Asymptomatic Mild to Moderate Aortic Valve Stenosis

The prognostic importance of left ventricular (LV) mass in nonsevere asymptomatic aortic stenosis has not been documented in a large prospective study.

The vulnerable right ventricle

PURPOSE OF REVIEW

The right ventricle (RV) is uniquely at risk in many patients with repaired or palliated congenital heart disease (CHD) such as tetralogy of Fallot, corrected transposition, single right ventricle, and in those with pulmonary hypertension. These patients live with abnormal cardiac loading conditions throughout their life, predisposing them to right heart failure.

RECENT FINDINGS

Standard heart failure therapies, developed to treat left ventricular failure, have failed to improve function or survival in patients with RV failure, suggesting a divergence in the molecular mechanisms of right versus left ventricular failure. As surgical techniques for repair of the most complex forms of RV-affecting CHDs continue to improve, more children with CHD will survive into adulthood. Long-term survival and quality of life will ultimately depend on our ability to preserve RV function.

SUMMARY

The purpose of this review is to highlight the differences between the right and left ventricular responses to stress, our current knowledge of how the RV adapts to the unique hemodynamic stressors experienced by patients with CHD, and the need to better understand the molecular mechanisms of RV failure, providing new targets for the development of RV-specific heart failure therapeutics.

Full-root aortic valve replacement with stentless xenograft achieves superior regression of left ventricular hypertrophy compared to pericardial stented aortic valves

BACKGROUND

Full-root aortic valve replacement with stentless xenografts has potentially superior hemodynamic performance compared to stented valves. However, a number of cardiac surgeons are reluctant to transform a classical stented aortic valve replacement into a technically more demanding full-root stentless aortic valve replacement. Here we describe our technique of full-root stentless aortic xenograft implantation and compare the early clinical and midterm hemodynamic outcomes to those after aortic valve replacement with stented valves.

METHODS

We retrospectively compared the pre-operative characteristics of 180 consecutive patients who underwent full-root replacement with stentless aortic xenografts with those of 80 patients undergoing aortic valve replacement with stented valves. In subgroups presenting with aortic stenosis, we further analyzed the intra-operative data, early postoperative outcomes and mid-term regression of left ventricular mass index.

RESULTS

Patients in the stentless group were younger (62.6 ± 13 vs. 70.3 ± 11.8 years, p < 0.0001) but had a higher Euroscore (9.14 ± 3.39 vs.6.83 ± 2.54, p < 0.0001) than those in the stented group. In the subgroups operated for aortic stenosis, the ischemic (84.3 ± 9.8 vs. 62.3 ± 9.4 min, p < 0.0001) and operative times (246.3 ± 53.6 vs. 191.7 ± 53.2 min, p < 0.0001) were longer for stentless versus stented valve implantation. Nevertheless, early mortality (0% vs. 3%, p < 0.25), re-exploration for bleeding (0% vs. 3%, p < 0.25) and stroke (1.8% vs. 3%, p < 0.77) did not differ between stentless and stented groups. One year after the operation, the mean transvalvular gradient was lower in the stentless versus stented group (5.8 ± 2.9 vs. 13.9 ± 5.3 mmHg, p < 0.0001), associated with a significant regression of the left ventricular mass index in the stentless (p < 0.0001) but not in the stented group (p = 0.2).

CONCLUSION

Our data support that full-root stentless aortic valve replacement can be performed without adversely affecting the early morbidity or mortality in patients operated on for aortic valve stenosis provided that the coronary ostia are not heavily calcified. The additional time necessary for the full-root stentless compared to the classical stented aortic valve replacement is therefore not detrimental to the early clinical outcomes and is largely rewarded in patients with aortic stenosis by lower transvalvular gradients at mid-term and a better regression of their left ventricular mass index.

Determinants of clinical improvement after surgical replacement or transcatheter aortic valve implantation for isolated aortic stenosis

Background

Transcatheter aortic valve implantation (TAVI) is an alternative to surgical aortic valve replacement (SAVR) in patients with aortic stenosis (AS) and high surgical risk. Hemodynamic performance after TAVI is superior, but the impact of reverse remodeling on clinical improvement is controversial. We aim to address the differences in hemodynamic changes between SAVR and TAVI, and its correlation with LV remodeling and clinical improvement at 6 months follow-up.

Methods

Forty-two patients treated by TAVI were compared with 45 SAVR patients with a stented bioprosthesis. Clinical, 2D and 3D echocardiographic data were prospectively obtained before and six months after intervention.

Results

Patients had similar distribution for sex, body surface area and AS severity. TAVI patients were older, more symptomatic and had more comorbidities. They also had higher LV filling pressures, larger 3D indexed left atrium volume, but similar 3D indexed LV mass. At 6 months, TAVI patients had greater clinical improvement and higher effective orifice area index (EAOI), but only SAVR patients already had a significant decrease in 3D indexed LV mass and diastolic volume. In univariate analysis older age, NYHA class ≥ III, increase in EAOI and TAVI were related with functional class improvement. After multivariate analysis only NYHA class ≥ III (OR 8.81, CI:2.13-36.52; p = 0.003) and an increase in EAOI ≥ 105% (OR 3.87, CI:1.02-14.70; p = 0.04) were predictors of clinical improvement.

Conclusions

At 6 months, functional class improvement was greater after TAVI. Higher initial NYHA class and an increase in EAOI ≥ 105% were independently associated with functional enhancement. It is debatable if left ventricular remodeling is determinant for functional class improvement.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-7120-12-41) contains supplementary material, which is available to authorized users.

Prognostic significance of LGE by CMR in aortic stenosis patients undergoing valve replacement

BACKGROUND

Prior studies have shown that late gadolinium enhancement (LGE) by cardiac magnetic resonance (CMR) can detect focal fibrosis in aortic stenosis (AS), suggesting that it might predict higher mortality risk.

OBJECTIVES

This study was conducted to evaluate whether LGE-CMR can predict post-operative survival in patients with severe AS undergoing aortic valve replacement (AVR).

METHODS

We prospectively evaluated survival (all-cause and cardiovascular disease related) according to LGE-CMR status in 154 consecutive AS patients (96 men; mean age: 74 ± 6 years) without a history of myocardial infarction undergoing surgical AVR and in 40 AS patients undergoing transcatheter aortic valve replacement (TAVR).

RESULTS

LGE was present in 29% of patients undergoing surgical AVR and in 50% undergoing TAVR. During a median follow-up of 2.9 years, 21 patients undergoing surgical AVR and 20 undergoing TAVR died. In surgical AVR, the presence of LGE predicted higher post-operative mortality (odds ratio: 10.9; 95% confidence interval [CI]: 1.2 to 100.0; p = 0.02) and worse all-cause survival (73% vs. 88%; p = 0.02 by log-rank test) and cardiovascular disease related survival (85% vs. 95%; p = 0.03 by log-rank test) on 5-year Kaplan-Meier estimates of survival after surgical AVR. Multivariate Cox analysis identified the presence of LGE (hazard ratio: 2.8; 95% CI: 1.3 to 6.9; p = 0.025) and New York Heart Association functional class III/IV (hazard ratio: 3.2; 95% CI: 1.1 to 8.1; p < 0.01) as the sole independent predictors of all-cause mortality after surgical AVR. The presence of LGE also predicted higher all-cause mortality (p = 0.05) and cardiovascular disease related mortality (p = 0.03) in the subgroup of patients without angiographic coronary artery disease (n = 110) and higher cardiovascular disease related mortality in 25 patients undergoing transfemoral TAVR.

CONCLUSIONS

The presence of LGE indicating focal fibrosis or unrecognized infarct by CMR is an independent predictor of mortality in patients with AS undergoing AVR and could provide additional information in the pre-operative evaluation of risk in these patients.

Load independent impairment of reverse remodeling after valve replacement in hypertensive aortic stenosis patients

BACKGROUND

We evaluated the impact of hypertension on the left ventricular mass regression in aortic stenosis after aortic valve replacement.

METHODS

We prospectively studied 135 patients with severe aortic stenosis at baseline and 1 year after surgery. In 32 patients we analyzed myocardial gene expression of collagen types I and III, connective tissue growth factor, transforming growth factor-β1, metalloproteinase-2 and its tissue inhibitor and compared its levels vs controls.

RESULTS

Seventy-six patients (56.3%) had a history of hypertension. Hypertensive patients were older, had higher Euroscore-II and NYHA class, with no differences in stenosis severity. At 1 year follow-up there was a median decrease of mass index of 14.2% (P25-75: -4.3%-30.4%; p<0.001). Mass regression was significantly higher in patients without hypertension, with a median decrease of 25.9% (P25-75: 12.0%-38.7%) vs 5.4% (P25-75: -12.5%-20.1%; p=0.001), despite similar increase in effective orifice area and no differences in valvuloarterial impedance. After 1 year, higher baseline left ventricular mass index (p=0.005) and the absence of hypertension (p=0.002) or diabetes (p=0.041) were the only independent predictors of mass regression higher than the median. Comparing with controls, aortic stenosis patients had an increased expression of collagen types I and III, but only hypertensive patients had higher relative expression of collagen type I vs III. In hypertensive patients TIMP2 expression was up-regulated and correlated with higher baseline left ventricular mass index (r=0.61; p=0.020).

CONCLUSIONS

In aortic stenosis, hypertension impairs mass regression one year after valve replacement, independently of total afterload. Differences in the expression of extracellular matrix remodeling genes might contribute to this finding.

Preserved prognostic value of preinterventional troponin T levels despite successful TAVI in patients with severe aortic stenosis

BACKGROUND

Elevated concentrations of troponin T have prognostic impact in patients with various cardiovascular diseases including those with severe aortic stenosis. Transcatheter aortic valve implantation (TAVI) has improved prognosis for patients without a surgical option. Whether this affects the prognostic value of preinterventional troponin T remains unclear.

METHODS

We therefore conducted a prospective study in 198 consecutive patients with subsequent, successful transfemoral TAVI and analyzed cardiac troponin T (cTnT) levels with a new generation, high-sensitive troponin T assay before and after TAVI, as well as their prognostic value after 12 months.

RESULTS

Patients with severe aortic stenosis (AS) showed significant elevation of preinterventional cTnT levels. Postinterventional cTnT levels significantly rose further about sevenfold after transfemoral TAVI and peaked at day three until they steadily declined thereafter. Baseline renal function (P = 0.011), the duration of intraprocedural rapid pacing (P = 0.0012), and baseline cTnT (P = 0.0001) values predicted the magnitude of postinterventional cTnT elevations. Interestingly, Kaplan-Meier curve analysis revealed, that although cTnT levels were not predictive for short-term mortality, preinterventional as well as postinterventional peak cTnT showed prognostic value for 1-year mortality, regardless of successful TAVI.

CONCLUSIONS

Pre- and postinterventional hscTnT levels signal adverse 1-year mortality in patients with severe AS independent of successful aortic valve replacement.

Myocardial and circulating levels of microRNA-21 reflect left ventricular fibrosis in aortic stenosis patients

BACKGROUND

Various human cardiovascular pathophysiological conditions associate aberrant expression of microRNAs (miRNAs) and circulating miRNAs are emerging as promising biomarkers. In mice, myocardial miR-21 overexpression is related to cardiac fibrosis elicited by pressure overload. This study was designed to determine the role of myocardial and plasmatic miR-21 in the maladaptive remodeling of the extracellular matrix induced by pressure overload in aortic stenosis (AS) patients and the clinical value of miR-21 as a biomarker for pathological myocardial fibrosis.

METHODS

In left ventricular biopsies from 75 AS patients and 32 surgical controls, we quantified the myocardial transcript levels of miR-21, miR-21-targets and ECM- and TGF-β-signaling-related elements. miR-21 plasma levels were determined in 25 healthy volunteers and in AS patients. In situ hybridization of miR-21 was performed in myocardial sections.

RESULTS

The myocardial and plasma levels of miR-21 were significantly higher in the AS patients compared with the controls and correlated directly with the echocardiographic mean transvalvular gradients. miR-21 overexpression was confined to interstitial cells and absent in cardiomyocytes. Using bootstrap validated multiple linear regression, the variance in myocardial collagen expression was predicted by myocardial miR-21 (70% of collagen variance) or plasma miR-21 (52% of collagen variance), together with the miR-21 targets RECK and PDCD4, and effectors of TGF-ß signaling.

CONCLUSIONS

Our results support the role of miR-21 as a regulator of the fibrotic process that occurs in response to pressure overload in AS patients and underscore the value of circulating miR-21 as a biomarker for myocardial fibrosis.

A mouse model of reverse cardiac remodelling following banding-debanding of the ascending aorta

AIM

Myocardial remodelling during pressure overload might contribute to development of heart failure. Reverse remodelling normally occurs following aortic valve replacement for aortic stenosis; however, the details and regulatory mechanisms of reverse remodelling remain unknown. Thus, an experimental model of reverse remodelling would allow for studies of this process. Although models of aortic banding are widely used, only few reports of debanding models exist. The aim of this study was to establish a banding-debanding model in the mouse with repetitive careful haemodynamic evaluation by high-resolution echocardiography.

METHODS

C57Bl/6 mice were subjected to ascending aortic banding and subsequent debanding. Cardiac geometry and function were evaluated by echocardiography, and left ventricular myocardium was analysed by histology and quantitative real-time polymerase chain reaction.

RESULTS

The degree of aortic banding was controlled by non-invasive estimation of the gradient, and we found a close correlation between left ventricular mass estimated by echocardiography and weight at the time of killing. Aortic banding led to left ventricular hypertrophy, fibrosis and expression of foetal genes, indicating myocardial remodelling. Echocardiography revealed concentric left ventricular remodelling and myocardial dysfunction. Following debanding, performed via a different incision, there was rapid regression of left ventricular weight and normalization of both cardiac geometry and function by 14 days.

CONCLUSIONS

We have established a reproducible and carefully characterized mouse model of reverse remodelling by banding and debanding of the ascending aorta. Such a model might contribute to increased understanding of the reversibility of cardiac pathology, which in turn might give rise to new strategies in heart failure treatment.

Dynamic microRNA expression during the transition from right ventricular hypertrophy to failure

MicroRNAs (miRs) are small, noncoding RNAs that are emerging as crucial regulators of cardiac remodeling in left ventricular hypertrophy (LVH) and failure (LVF). However, there are no data on their role in right ventricular hypertrophy (RVH) and failure (RVF). This is a critical question given that the RV is uniquely at risk in patients with congenital right-sided obstructive lesions and in those with systemic RVs. We have developed a murine model of RVH and RVF using pulmonary artery constriction (PAC). miR microarray analysis of RV from PAC vs. control demonstrates altered miR expression with gene targets associated with cardiomyocyte survival and growth during hypertrophy (miR 199a-3p) and reactivation of the fetal gene program during heart failure (miR-208b). The transition from hypertrophy to heart failure is characterized by apoptosis and fibrosis (miRs-34, 21, 1). Most are similar to LVH/LVF. However, there are several key differences between RV and LV: four miRs (34a, 28, 148a, and 93) were upregulated in RVH/RVF that are downregulated or unchanged in LVH/LVF. Furthermore, there is a corresponding downregulation of their putative target genes involving cell survival, proliferation, metabolism, extracellular matrix turnover, and impaired proteosomal function. The current study demonstrates, for the first time, alterations in miRs during the process of RV remodeling and the gene regulatory pathways leading to RVH and RVF. Many of these alterations are similar to those in the afterload-stressed LV. miRs differentially regulated between the RV and LV may contribute to the RVs increased susceptibility to heart failure.

Effects of phosphodiesterase type 5 inhibition on systemic and pulmonary hemodynamics and ventricular function in patients with severe symptomatic aortic stenosis

BACKGROUND

Pressure overload resulting from aortic stenosis causes maladaptive ventricular and vascular remodeling that can lead to pulmonary hypertension, heart failure symptoms, and adverse outcomes. Retarding or reversing this maladaptive remodeling and its unfavorable hemodynamic consequences has the potential to improve morbidity and mortality. Preclinical models of pressure overload have shown that phosphodiesterase type 5 inhibition is beneficial; however, the use of phosphodiesterase type 5 inhibitors in patients with aortic stenosis is controversial because of concerns about vasodilation and hypotension.

METHODS AND RESULTS

We evaluated the safety and hemodynamic response of 20 subjects with severe symptomatic aortic stenosis (mean aortic valve area, 0.7 ± 0.2 cm(2); ejection fraction, 60 ± 14%) who received a single oral dose of sildenafil (40 or 80 mg). Compared with baseline, after 60 minutes, sildenafil reduced systemic (-12%; P<0.001) and pulmonary (-29%; P=0.002) vascular resistance, mean pulmonary artery (-25%; P<0.001) and wedge (-17%; P<0.001) pressures, and increased systemic (13%; P<0.001) and pulmonary (45%; P<0.001) vascular compliance and stroke volume index (8%; P=0.01). These changes were not dose dependent. Sildenafil caused a modest decrease in mean systemic arterial pressure (-11%; P<0.001) but was well tolerated with no episodes of symptomatic hypotension.

CONCLUSIONS

This study shows for the first time that a single dose of a phosphodiesterase type 5 inhibitor is safe and well tolerated in patients with severe aortic stenosis and is associated with improvements in pulmonary and systemic hemodynamics resulting in biventricular unloading. These findings support the need for longer-term studies to evaluate the role of phosphodiesterase type 5 inhibition as adjunctive medical therapy in patients with aortic stenosis.

Mass reduction and functional improvement of the left ventricle after aortic valve replacement for degenerative aortic stenosis

Background

Left ventricular (LV) hypertrophy caused by aortic valve stenosis (AS) leads to cardiovascular morbidity and mortality. We sought to determine whether aortic valve replacement (AVR) decreases LV mass and improves LV function.

Materials and Methods

Retrospective review for 358 consecutive patients, who underwent aortic valve replacement for degenerative AS between January 1995 and December 2008, was performed. There were 230 men and 128 women, and their age at operation was 63.2±10 years (30~85 years).

Results

There was no in-hospital mortality, and mean follow-up duration after discharge was 48.9 months (2~167 months). Immediate postoperative echocardiography revealed that LV mass index and mean gradient across the aortic valve decreased significantly (p<0.001), and LV mass continued to decrease during the follow-up period (p<0.001). LV ejection fraction (EF) temporarily decreased postoperatively (p<0.001), but LV function recovered immediately and continued to improve with a significant difference between preoperative and postoperative EF (p<0.001). There were 15 late deaths during the follow-up period, and overall survival at 5 and 10 years were 94% and 90%, respectively. On multivariable analysis, age at operation (p=0.008), concomitant coronary bypass surgery (p<0.003), lower preoperative LVEF (<40%) (p=0.0018), and higher EUROScore (>7) (p=0.045) were risk factors for late death.

Conclusion

After AVR for degenerative AS, reduction of left ventricular mass and improvement of left ventricular function continue late after operation.

Noninvasive assessment of filling pressure and left atrial pressure overload in severe aortic valve stenosis: relation to ventricular remodeling and clinical outcome after aortic valve replacement

OBJECTIVE

One of the hemodynamic consequences of aortic valve stenosis is pressure overload leading to left atrial dilatation. Left atrial size is a known risk factor providing prognostic information in several cardiac conditions. It is not known if this is also the case in patients with aortic valve stenosis after aortic valve replacement.

METHODS

A total of 119 patients with severe aortic valve stenosis scheduled for aortic valve replacement were evaluated preoperatively and divided into 2 groups according to left atrial volume index (≥40 mL/m(2)). Echocardiography was repeated 12 months after surgery. Patients were followed up for 24 months. The primary end point was the composite end point overall mortality and hospitalization due to congestive heart failure.

RESULTS

Preoperative left atrial dilation was associated with left ventricular hypertrophy and increased filling pressure. Preoperative left atrial volume index was associated with persistent abnormalities in left ventricular filling pressure and left ventricular mass index at 1 year after surgery. Event-free survival in patients with left atrial volume index of 40 mL/m(2) or more at 1 year was 71% compared with 88% in patients with left atrial volume index less than 40 mL/m(2) (P = .002). Patients with preoperative increased E/e' ratio and left ventricular hypertrophy were at increased risk. In Cox regression analysis after correcting for standard risk factors, left atrial volume index was found to be the only significant predictor of the composite end point. In a forward conditional multivariable model, left atrial volume index 40 mL/m(2) or greater (hazard ratio, 4.2 [1.6-10.7]; P = .003) remained an independent predictor, whereas E/e' was borderline significant (P = .06).

CONCLUSIONS

In patients with symptomatic severe aortic valve stenosis undergoing aortic valve replacement, left atrial volume provides important prognostic information beyond standard risk factors.

Plasma IL-18 and IL-18BP are altered differently in reverse remodeling following aortic valve replacement

OBJECTIVES

Patients with aortic stenosis (AS) develop left ventricular remodeling characterized by changes in extracellular matrix (ECM) and cardiomyocyte-hypertrophy. Aortic valve replacement (AVR) reverses this process (reverse remodeling). We examined plasma levels of interleukin-18 (IL-18) and its binding protein (IL-18BP) before and after AVR for AS since these mediators have been shown experimentally to exert effects on myocardial remodeling.

DESIGN

Plasma levels of IL-18 and IL-18BP were analyzed in 22 patients with AS undergoing AVR, preoperatively, two days, six and 12 months postoperatively. Echocardiography and functional testing were performed.

RESULTS

IL-18BP was significantly increased by 28% and 15% at two days and six months after AVR, compared to preoperative values. In contrast, IL-18 showed a later peak (increased by 24% at 12 months postoperatively) when IL-18BP was normalized. IL-18 correlated positively with deceleration time (R = 0.44) at this time-point which might indicate an association with diastolic function.

CONCLUSIONS

We report for the first time that plasma IL-18 and IL-18BP are differentially regulated after AVR for AS with an early increase in IL-18BP postoperatively followed by a later peak in IL-18 at 12 months. Given the known effects of these mediators on myocardial remodeling and function, they might play a role in the reverse and remodeling process associated with AVR.

Impact of hypertension on left ventricular hypertrophy regression and exercise capacity in patients operated for aortic valve stenosis

OBJECTIVES

To assess the influence of concomitant hypertension on left ventricular hypertrophy regression and exercise capacity in patients operated for aortic stenosis.

DESIGN

We performed echocardiography 1 week, 6- and 18-month postoperatively in 78 patients, aged 70 (28-86) years, who received Medtronic Hall (33), Biocor (8), Carpentier-Edwards S.A.V. (14) and Freestyle (23) prosthetic valves for severe aortic stenosis. Forty nine patients participated in treadmill tests with ergospirometry at the 6- and 18-month visits.

RESULTS

Left ventricular mass index was comparably reduced in normotensive and hypertensive patients (34 vs. 40 g/m2 after 6 months, and 43 vs. 46 g/m2 after 18 months, ns). In multiple regression analysis, adjusting for baseline left ventricular mass index, larger reduction in left ventricular mass index was associated with younger age and having a Freestyle prosthesis, but not with gender or history of hypertension (multiple R2=0.68, p < 0.05). Exercise capacity assessed as peak oxygen uptake increased from early to late evaluation in normotensive patients (VO2max 24.27 vs. 27.08 ml/kg/min, p < 0.05) while remained unchanged in hypertensive patients (VO2max 22.2 vs. 21.1 ml/kg/min). In multiple regression analysis, higher improvement in exercise capacity was predicted by male gender, younger age and absence of hypertension, while no independent association was found with Freestyle prosthesis (multiple R2 = 0.37, p < 0.05).

CONCLUSIONS

In patients operated for aortic stenosis, concomitant hypertension is associated with lack of improvement in exercise capacity in spite of early left ventricular hypertrophy reduction comparable to what is found in normotensive patients.

Alterations in circulating activin A, GDF-15, TGF-beta3 and MMP-2, -3, and -9 during one year of left ventricular reverse remodelling in patients operated for severe aortic stenosis

BACKGROUND

Patients with aortic stenosis (AS) develop left ventricular remodelling with cardiomyocyte hypertrophy and increased fibrosis. Following aortic valve replacement (AVR) reverse remodelling usually takes place.

AIMS

To examine circulating levels of members of the transforming growth factor (TGF) beta superfamily and matrix metalloproteinases (MMP), known to have important effects on hypertrophy and extracellular matrix, in patients operated for AS.

METHODS

Circulating levels of activin A, GDF-15, TGF-beta3, MMP-2, -3, and -9 were measured in twenty-two patients undergoing AVR preoperatively, and 2 days, six months and 12 months postoperatively. Echocardiography and a six minute walking test evaluated reverse remodelling and physical performance.

RESULTS

Activin A increased at six (1081.00+/-98.05 pg/ml, p<0.05) and twelve months (1263.09+/-141.43 pg/ml, p<0.05) compared to the preoperative value (855.00+/-76.30 pg/ml) and correlated negatively to physical performance. The preoperative value was also increased compared to controls (639.54+/-63.05 pg/ml, p<0.05). GDF-15, MMP-3 and -9 were all increased at two days postoperatively (p<0.05). MMP-3 correlated with left ventricular end diastolic dimension (p<0.05). MMP-2 did not change during the study period. TGF-beta3 was only slightly reduced at six months postoperatively.

CONCLUSION

The observed alteration in circulating levels of members of the TGF-beta superfamily and MMPs might play a role in the reverse remodelling process following AVR for AS.

Left ventricular systolic and diastolic function in asymptomatic patients with moderate aortic stenosis

Tissue Doppler imaging (TDI) has improved the ability to detect subclinical changes in left ventricular (LV) function. The aim of this study was to investigate if asymptomatic patients with moderate aortic stenosis (AS) had impaired LV systolic and diastolic function. Fifty patients (mean age 65 +/- 12 years) recruited into the multicenter Simvastatin + Ezetimibe in Aortic Stenosis (SEAS) study with aortic peak velocities of 2.5 and 4.0 m/s were compared with 26 healthy subjects (mean age 64 +/- 12 years) (p = NS). Peak systolic tissue velocities and strain were measured at 8 LV locations and averaged. Early diastolic tissue velocity from the septal mitral annulus (E'sep) was measured as an index of LV relaxation. The ratio of early diastolic transmitral pulsed Doppler (E) to E'sep (E/E'sep) was calculated as an index of LV filling pressure. Peak systolic tissue velocity (4.1 +/- 1.0 vs 4.8 +/- 1.1 cm/s, p <0.01) and strain (-16.6 +/- 2.7% vs -17.9 +/- 2.0%, p <0.05) were decreased in patients with AS compared with controls. E'sep was decreased (4.9 +/- 1.0 vs 5.8 +/- 1.3 cm/s, p <0.01) and E/E'sep was increased (17.4 +/- 9.7 vs 11.7 +/- 3.8, p <0.01) in the AS group compared with the control group. In conclusion, asymptomatic patients with moderate AS have impaired LV systolic function as measured by reduced peak systolic tissue velocity and strain. Augmented LV filling pressure measured by E/E'sep and impaired LV relaxation measured by reduced E'sep also indicate diastolic dysfunction in these patients.

Left ventricular hypertrophy and remodeling after aortic valve replacement

Left ventricular geometric remodeling and regression of hypertrophy were assessed after aortic valve replacement with a mechanical prosthesis in 37 patients with aortic stenosis and 39 with aortic insufficiency, aged 54.2 +/- 14.3 and 52.6 +/- 16.6 years, respectively. The follow-up period was 2 years. In patients with aortic insufficiency, ejection fraction increased from 54.4 +/- 3.5 preoperatively to 59.6 +/- 3.4 after 6 months and 61.7 +/- 2.7 after 2 years. In patients with aortic stenosis, ejection fraction increased from 56.6 +/- 5.1 preoperatively to 63.9 +/- 4.4 after 6 months and 71.7 +/- 4.1 after 2 years. Geometric remodeling, regression of hypertrophy, and increased ejection fraction of the left ventricle were similar in both groups at 6 months after surgery, but after 2 years of follow-up, greater improvement was found in patients who had undergone valve replacement for aortic stenosis.

Early Hemodynamic Results of the Shelhigh SuperStentless Aortic Bioprostheses

BACKGROUND

Stentless valves have been demonstrated excellent hemodynamic performances favoring the recovery of left ventricular function and the ventricular hypertrophy regression. The aim of the study was to evaluate the early hemodynamic performance of the Shelhigh SuperStentless aortic valve (AV).

METHODS

Between July 2003 and June 2005, 35 patients (18 females; age 70.8 +/- 11.7 years, range: 22-85) underwent AV replacement with the Shelhigh SuperStentless bioprostheses. Most recurrent etiology was senile degeneration in 25 (71%) patients and 24 (69%) were in New York Heart Association (NYHA) functional class III or IV. Concomitant coronary artery bypass grafting was performed in nine patients (25.7%) and mitral valve surgery in two patients (5.7%). Doppler echocardiography was performed before surgery, at six-month and one-year follow-up.

RESULTS

There were no hospital deaths and no valve-related perioperative complications. During one-year follow-up, no endocarditis or thromboembolic events were registered, no cases of structural dysfunction or valve thrombosis were noted. Mean and peak transvalvular gradients significantly decrease after AV replacement, with an evident reduction to approximately 50% of the preoperative values at six months. A 20% reduction was also observed for left ventricular mass (LVM) index at six months, with a further regression at one year. Correspondingly, significant increases in effective orifice area (EOA) and indexed EOA were determined after surgery (0.87 +/- 0.14 versus 1.84 +/- 0.29 cm2 and 0.54 +/- 0.19 versus 1.05 +/- 0.20 cm2/m2, respectively). Valve prosthesis-patient mismatch was moderate in five patients and severe in one case.

CONCLUSIONS

Shelhigh SuperStentless AV provided good and encouraging hemodynamic results. Long-term follow-up is necessary to evaluate late hemodynamic performance and durability of this stentless bioprosthesis.

Recovery of Left Ventricular Systolic Longitudinal Strain After Valve Replacement in Aortic Stenosis and Relation to Natriuretic Peptides

OBJECTIVE

We sought to examine left ventricular (LV) longitudinal systolic myocardial contractility in isolated valvular aortic stenosis (AS) before and after valve replacement and relation to natriuretic peptides.

METHODS

In all, 45 patients with symptomatic AS without significant coronary artery disease were studied by serial tissue Doppler echocardiography and analysis of plasma atrial and brain natriuretic peptide (Nt-pro-BNP).

RESULTS

LV myocardial systolic strain was significantly reduced in AS with preserved ejection fraction and most pronounced in patients with advanced heart failure symptoms. Nt-pro-BNP was significantly related to LV mass index and mean LV strain (r = 0.63, P < .001; and r = 0.61, P < .001, respectively). Mean myocardial systolic strain increased after valve replacement (baseline -9 +/- 4% vs -14 +/- 4% at 12 months, P < .001). The increase of systolic strain and the observed regression of LV mass index were independently related to changes of Nt-pro-BNP (r = -0.67, P < .001; and r = -0.71, P < .001, respectively) during 12 months of follow-up after valve replacement. A significant association was found between changes of plasma atrial natriuretic peptide and echocardiographic markers of LV diastolic function.

CONCLUSION

LV longitudinal systolic strain is severely depressed despite preserved LV ejection fraction and fractional shortening in AS. A significant association exists among natriuretic peptides, myocardial longitudinal contractility, and the degree of symptoms. Reverse LV remodeling after aortic valve replacement with regression of myocardial hypertrophy results in improvement of LV longitudinal myocardial strain and decrease of Nt-pro-BNP plasma levels. LV strain analysis might have the potential to identify patients with asymptomatic AS who might benefit from earlier surgical intervention to preserve overall LV function.

Effect of the increase in valve area after aortic valve replacement with a 19-mm aortic valve prosthesis on left ventricular mass regression in patients with pure aortic stenosis

OBJECTIVES

Although patients with aortic stenosis, who receive 19-mm valves, are at high risk for prosthesis-patient mismatch, most of them show a significant left ventricular mass (LVM) regression postoperatively. The aim of this study was to identify factors predicting postoperative relative LVM regression in this subgroup of patients.

METHODS

A population of 44 patients operated on for pure aortic stenosis and receiving a 19-mm valve was studied by echocardiography at 1.4 +/- 0.5 years postoperatively.

RESULTS

The mean relative LVM regression was -19.3 +/- 18.9%, the mean gradient drop was -31.6 +/- 13.3 mmHg, and the mean Delta increase in aortic area index (postoperative aortic area index minus preoperative aortic area index) was 0.30 +/- 0.14 cm/m. Thirty-two patients had an indexed effective orifice area of less than 0.8 cm/m. At multivariate analysis (r = 0.63; r = 40%; P < 0.0001) preoperative LVM (P = 0.006), hypertension (P = 0.018) and Delta aortic area index (P = 0.049) were independent predictors of relative LVM regression.

CONCLUSIONS

Our study shows that, at least 1 year postoperatively, in patients receiving a 19-mm valve, LVM regression is influenced by several parameters, in particular preoperative LVM, hypertension and the magnitude of the increase in aortic area.

Evaluation of Left Ventricular Functions after Aortic Valve Replacement in a Specific Young Male Patient Population with Pure Aortic Insufficiency or Aortic Stenosis: 5-Years Follow-up

BACKGROUND

The aim of this study was to evaluate the left ventricular functions and the regression of left ventricular hypertrophy after aortic valve replacement (AVR) in young male patients with pure aortic stenosis or aortic insufficiency with no additional disease.

METHODS

Young male patients who underwent AVR because of pure aortic stenosis (AS = 68) and insufficiency (AI = 70) were enrolled in the study. The mean age was 23.2 +/- 1.3 and 22.6 +/- 1.6 years, respectively. The follow-up time was 5 years. The parameters checked by transthoracic echocardiography were interventricular septum diastolic thickness, left ventricular posterior wall diastolic thickness, left ventricular end-diastolic diameter, left ventricle mass, left ventricle mass index, ejection fraction, and peak aortic gradient. Relative ventricle wall thickness was also calculated. Both groups values from the preoperative, postoperative sixth month, second year, and fifth year time intervals were compared.

RESULTS

In the AS group, the preoperative left ventricular ejection fraction (%) value of 53.68 +/- 5.04 increased to 63.24 +/- 4.11 at the end of the fifth year. In the AI group, the preoperative left ventricular ejection fraction (%) value of 48.40 +/- 3.56 increased to 59.77 +/- 2.75 at the end of the fifth year. The other left ventricular geometric parameters were also compared within each group. At the end of the fifth year, there were significant and positive changes in each group.

CONCLUSION

The regression of the left ventricular parameters is a process that occurs over many years following the correction of the primary hemodynamic abnormality. Although the results were similar in the AI and AS group, in the AS group the remodeling process had earlier results than in the AI group.

Impact of the improvement of valve area achieved with aortic valve replacement on the regression of left ventricular hypertrophy in patients with pure aortic stenosis

BACKGROUND

Previous studies have reported that patient-prosthesis mismatch may be associated with lesser regression of left ventricular hypertrophy. However, among the patients with mismatch, the extent of left ventricular mass regression varied markedly from one patient to another, and we hypothesized that it could be related to the magnitude of the increase in valve area achieved with aortic valve replacement. Our aim was to examine the relationship between the improvement in valve effective orifice area obtained with aortic valve replacement and the extent of postoperative left ventricular mass regression in patients with patient-prosthesis mismatch.

METHODS

Preoperative and postoperative measurements of valve effective orifice area, transvalvular pressure gradient, and left ventricular mass were obtained by Doppler echocardiography in 111 patients with pure aortic stenosis who were found to have patient-prosthesis mismatch based on an indexed effective orifice area of 0.8 cm2/m2 or less after operation.

RESULTS

On average, the valve effective orifice area increased by 0.45 +/- 0.24 cm2/m2 with operation, and mean transvalvular pressure gradients decreased by -31.6 +/- 13.5 mm Hg. The absolute and relative differences between preoperative and postoperative left ventricular mass were -28 +/- 30 g and -17% +/- 18%, respectively. In multivariate analysis, higher preoperative left ventricular mass (p < 0.0001) and larger increase in indexed valve effective orifice area with operation (p = 0.019) were independently associated with greater left ventricular mass regression.

CONCLUSIONS

This study shows that in patients with patient-prosthesis mismatch, the degree of left ventricular mass regression is influenced by the increase in valve effective orifice area achieved by aortic valve replacement.

Factors affecting left ventricular remodeling after valve replacement for aortic stenosis. An overview

Although a small percentage of patients with critical aortic stenosis do not develop left ventricle hypertrophy, increased ventricular mass is widely observed in conditions of increased afterload. There is growing epidemiological evidence that hypertrophy is associated with excess cardiac mortality and morbidity not only in patients with arterial hypertension, but also in those undergoing aortic valve replacement. Valve replacement surgery relieves the aortic obstruction and prolongs the life of many patients, but favorable or adverse left ventricular remodeling is affected by a large number of factors whose specific roles are still a subject of debate. Age, gender, hemodynamic factors, prosthetic valve types, myocyte alterations, interstitial structures, blood pressure control and ethnicity can all influence the process of left ventricle mass regression, and myocardial metabolism and coronary artery circulation are also involved in the changes occurring after aortic valve replacement. The aim of this overview is to analyze these factors in the light of our experience, elucidate the important question of prosthesis-patient mismatch by considering the method of effective orifice area, and discuss surgical timings and techniques that can improve the management of patients with aortic valve stenosis and maximize the probability of mass regression.

The effect of aortic valve replacement on plasma B-type natriuretic peptide in patients with severe aortic stenosis - one year follow-up

BACKGROUND

B-type natriuretic peptide (BNP) is synthesized in cardiac tissue in response to increased wall stress and myocardial hypertrophy.

AIMS

In patients with severe aortic stenosis (AS) we examined the effect of aortic valve replacement (AVR) on plasma BNP and association between BNP and left ventricular mass index (LVMI) preoperatively and in the reverse-remodeling phase twelve months postoperatively. We also examined the correlation between BNP and NYHA-class and between BNP and age.

METHODS AND RESULTS

Plasma BNP analyses and echocardiographic measurements were performed preoperatively, before discharge after AVR, and at twelve months in twenty-two patients. BNP was additionally measured at six months. Preoperatively, BNP was 283+/-45 pg/ml (mean+/-SEM). Following an immediate postoperative increase (441+/-38 pg/ml), BNP values decreased towards normal values at six and twelve months (139+/-25 and 130+/-18 pg/ml, respectively). LVMI was 206.5+/-15.8 g/m(2) preoperatively and decreased to 119.7+/-7.2 g/m(2) at twelve months with a correlation between LVMI and BNP preoperatively only (r=0.45, p<0.05). There was no correlation between BNP and NYHA-class, whereas BNP correlated to age both pre- and post-operatively.

CONCLUSION

We report an increase in plasma BNP in patients with AS. Following a further transient increase postoperatively, BNP levels decreased at six and twelve months after AVR. BNP correlated with LVMI preoperatively, and with age both preoperatively and at twelve months.

Randomized Comparison of Stentless Versus Stented Valves for Aortic Stenosis

BACKGROUND

Aortic valve replacement (AVR) is the established treatment for severe aortic stenosis. In response to the long-term results of aortic homografts, stentless porcine valves were introduced as an alternative low-resistance valve. We conducted a randomized trial comparing a stentless with a stented porcine valve in adults with severe aortic stenosis.

METHODS AND RESULTS

The primary outcome was change in left ventricular mass index (LVMI) measured by transthoracic echocardiography and, in a subset, by cardiovascular MR. Measurements were taken before valve replacement and at 6 and 12 months. Patients undergoing AVR with an aortic annulus < or =25 mm in diameter were randomly allocated to a stentless (n=93) or a stented supra-annular (n=97) valve. There were no significant differences in mean LVMI between the stentless versus stented groups at baseline (176+/-62 and 182+/-63 g/m2, respectively) or at 6 months (142+/-49 and 131+/-45 g/m2, respectively), although within-group changes from baseline to 6 months were highly significant. Changes in LVMI measured by cardiovascular MR (n=38) were consistent with the echo findings. There was a greater reduction in peak aortic velocity (P<0.001) and a greater increase in indexed effective orifice area (P<0.001) in the stentless group than in the stented group. There were no differences in clinical outcomes between the 2 valve groups.

CONCLUSIONS

Despite significant differences in indexed effective orifice area and peak flow velocity in favor of the stentless valve, there were similar reductions in left ventricular mass at 6 months with both stented and stentless valves, which persisted at 12 months.

Timing of aortic valve replacement in elderly patients with symptomatic aortic valve disease using outpatient clinical parameters

OBJECTIVE

To determine by how far worsening outpatient clinical parameters can affect outcome after aortic valve replacement, in patients with preserved left ventricular function and symptomatic aortic valve disease.

PATIENTS AND METHODS

Five hundred patients with aortic valve disease underwent aortic valve replacement using a bioprosthesis. In 348 patients, another procedure was added. The preoperative outpatient parameters were investigated for their effect on hospital and long-term mortality. A Fisher exact, Kaplan-Meier univariate and Cox proportional hazard analysis were used.

RESULTS

A retrospective follow-up of 2022 patient years was obtained. Five preoperative parameters were found to be more present in patients with a decreased left ventricular function: 1) severity of symptoms, 2) previous myocardial infarction, 3) conduction defects, 4) aortic valve regurgitation and 5) increasing need for medication. In patients with an ejection fraction of 50% or more, logistic regression analysis showed that hospital mortality increased with need for medication (p=0.004), previously performed CABG (0.015), increase in symptoms (p=0.018) and myocardial infarction (p=0.034). A Kaplan-Meier analysis revealed aortic valve regurgitation (p=0.017) and increased need for medication (p=0.012) as significant on long-term survival. Presence of a previous myocardial infarction showed a trend (p=0.062). A Cox' proportional hazard analysis showed for global mortality increased need for medication (p=0.010) and previous myocardial infarction (p=0.018) as independent factors and for long-term mortality, this was aortic valve regurgitation (p=0.001).

CONCLUSIONS

Results after aortic valve replacement deteriorate with the presence of valve regurgitation, a preoperative myocardial infarction, increasing need for medication or severity of symptoms, even for an ejection fraction of 50% or more. Anamnesis with special care to the degree of symptoms and increasing need for medication early in the valve disease could lead to early referral, thereby reducing number of patients with severe symptoms and improving postoperative results.

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.

Hemodynamic function of the standard St. Jude bileaflet disc valve has no clinical impact 10 years after aortic valve replacement

OBJECTIVES

Size mismatch and impaired left ventricular function have been shown to determine the hemodynamic function of the standard St. Jude bileaflet disc valve early after aortic valve replacement (AVR). We aimed to analyse St. Jude valve hemodynamic function and its clinical impact in the survivors of a prospective series 10 years after AVR for aortic stenosis.

DESIGN

Forty-three survivors aged 32-90 years from a prospective series attended a follow-up study with Doppler echo and radionuclide cardiography 10 years after AVR for aortic stenosis. Six patients with significant left sided valve regurgitation were excluded from further analysis: they had significantly lower St. Jude valve gradient and left ventricular ejection fraction (LVEF) and larger mass index (LVMi) than 37 without.

RESULTS

In the 37 patients without left sided valve regurgitation peak and mean gradients were inversely related to St. Jude valve geometric orifice area (GOA) indexed for either body surface area or left ventricular end-diastolic dimension (LVEDD). The gradients correlated directly with LVEDD but not with LVEF or LVMi. Eleven patients with hypertension had higher peak gradients (31+/-13 versus 22+/-8 mmHg, p<0.05), lower LVEF, and higher LVEDD and LVMi than 26 without. Peak gradient was greater than 35 mmHg in five hypertensive patients with normal LVEF but lesser than 30 mmHg in six with impaired LVEF. Supranormal LVEF and severe size mismatch identified the remaining patients (N=3) with peak gradient above 35 mmHg. In a multilinear regression analysis GOA indexed for LVEDD, hypertension, and LVEF were independently related to peak gradient.

CONCLUSION

High gradients of the standard St. Jude bileaflet disc valve 10 years after AVR was primarily related to systemic hypertension and mismatch between valve and left ventricular cavity size. Hypertension and left sided valve regurgitation, but not St. Jude valve gradient or size mismatch, were the dominant determinants of left ventricular hypertrophy and impaired function.

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.

Myocardial function in severe aortic stenosis before and after aortic valve replacement: A Doppler tissue imaging study

BACKGROUND

The aim of the study was to assess the value of Pulsed-wave Doppler tissue imaging (DTI) in assessing diastolic and systolic function in patients with severe aortic value stenosis.

METHODS

Thirty-five patients with aortic stenosis (AS) (valve orifice < or = 1 cm 2 , mean age 71.8 +/- 6.2) and 35 comparable healthy subjects were studied. All subjects performed conventional 2-dimensional Doppler echocardiography and DTI at mitral annulus level. Patients with AS were divided into 2 groups: 16 patients who presented initial signs of HF and a depressed left ventricular systolic function (AS I) (EF: 35%-50%) and 19 patients were asymptomatic and had normal left ventricular systolic function (EF > 50%) (ASII). The 16 symptomatic AS patients underwent surgical aortic valve replacement and were examined after 1 year.

RESULTS

DTI was able to detect abnormalities of systolic and diastolic function in AS: the significantly lower peak S velocity in AS I than in AS II and in controls, both at septum and lateral wall level; the significantly lower peak E velocity in AS I than in AS II and in controls both at septum and lateral wall level; the significantly higher peak A velocity in AS I than in AS II and in controls both at septum and lateral wall level; the significant lower E/A ratio in AS I than in AS II and in controls both at septum and lateral wall level.

CONCLUSION

We found a significant inverse correlation between DTI lateral S velocity, DTI peak E velocity, lateral DTI E/A ratio, and AS peak and mean gradient. According to the results of this study we can affirm that DTI parameters surely had an important physiopathological impact in the knowledge of myocardial function in patients with severe aortic stenosis.

Early Regional Assessment of LV Mass Regression and Function after Stentless Valve Replacement: Comparative Randomized Study

Early regional performance and hypertrophy regression after stentless aortic valve replacement are still incompletely characterized. We compared early postoperative changes of segmental thickness and function after stentless and stented aortic valve replacement as assessed by cardiac magnetic resonance (CMR). In 16 patients randomly assigned to stented (Mosaic, 8 patients) and stentless (Freestyle, 8 patients) groups, 4 parallel short-axis images at the level of the apex (slice 4), midventricle (slices 2-3), and mitral valve (slice 1) were obtained with a 1.5 T CMR scanner (Magnetom Sonata, Siemens) before and 1 month after surgery. Cine images were obtained using an echo gradient sequence. Left ventricle mass was calculated as the difference between the left ventricular end-diastolic volume at the epicardial and endocardial borders multiplied by a myocardium density factor (1.05). Each slice was divided into 8 segments (octants) from anterior (octant I-II) to septal (octant V-VIII). A total of 32 segments encompassed the entire heart. From each of these elements end diastolic thickness and systolic function (fractional thickening) were calculated. In stentless valves significant reduction of septal octant thickness on the midventricular slice was noted. There was no difference in regional systolic function-segment thickening. In stented valves no segmental thickness changes were observed. In stentless valves there was early postoperative thickness reduction of septal segments at the midventricular level. However, this finding did not coincide with changes in segmental function.

Mass regression in aortic stenosis after valve replacement with small size pericardial bioprosthesis

BACKGROUND

The aim of the study was to determine whether left ventricular mass regression is influenced by valve size after the implantation of a Carpentier-Edwards Perimount (CEP) pericardial bioprosthesis for pure aortic stenosis.

METHODS

Patients receiving 19-mm, 21-mm, and 23-mm CEP aortic valves underwent echocardiography preoperatively and at least 1 year after surgery (mean, 2.3 +/- 1 years) and the echocardiograms were compared within and between groups.

RESULTS

The study involved a total of 88 patients: 34 receiving 19-mm CEPs, 29 receiving 21-mm CEPs, and 25 receiving 23-mm CEPs. The mean postoperative prosthetic gradients were respectively 20.6 +/- 6.6 mm Hg, 17.9 +/- 5.8 mm Hg, and 13.2 +/- 4.1 mm Hg (p = 0.0001); the mean postoperative valve areas were respectively 1.24 +/- 0.16 cm(2), 1.45 +/- 0.2 cm(2), and 1.63 +/- 0.21 cm(2) (p = 0.0001). In comparison with the preoperative echocardiographic measurements absolute left ventricular mass significantly decreased by -54.1 +/- 48.8 g, -54.1 +/- 55.1 g, and -74.4 +/- 57.4 g respectively with no statistically significant between-group difference (analysis of variance) but ventricular septum and posterior wall thickness significantly decreased in each group (p < 0.05).

CONCLUSIONS

The implantation of 19-mm, 21-mm, and 23-mm CEP aortic prostheses significantly reduces left ventricular mass without any size-related differences.

Left ventricular remodeling in hearts with tricuspid atresia: morphologic observations and possible basis for ventricular dysfunction after surgery

OBJECTIVES

This study was undertaken to assess the pattern of left ventricular hypertrophy, the myocardial capillary network, and the extracellular matrix in hearts with tricuspid atresia.

METHODS

We examined 32 hearts with tricuspid atresia and 27 normal hearts from control subjects with similar age and sex distribution. Wall thickness, inlet length, and outlet length were obtained from the left ventricle. Immunohistochemical staining for von Willebrand factor was used to label myocardial capillaries. By means of computer-assisted morphometry, the following data were obtained from the inlet, apex, and outlet of the left ventricle: transverse myocyte diameter, myocyte nuclear volume fraction, capillary volume fraction, interstitial fibrous volume fraction, and endocardial thickness.

RESULTS

The wall thickness in affected hearts was not different from that in control hearts. The left ventricular outlet length was significantly greater in the malformed hearts (P =.005). The myocyte diameter did not differ from that in control hearts. The capillary volume fraction was decreased in the malformed hearts (P <.001). The interstitial fibrous deposition was greater in the malformed hearts at all sites analyzed (P <.001). Fibrosis was greater in the inlet and apex (P =.004) and also in the subendocardial half of the ventricular wall than in the subepicardial half. According to a logistic regression model, age was the only variable associated with the probability of occurrence of fibrosis.

CONCLUSIONS

Our findings in hearts with tricuspid atresia possibly represent chronically induced volume overload in the presence of ischemia, rather than a typical model of volume overload. A decreased capillary volume fraction may indicate a greater susceptibility to ischemia. Fibrous deposition probably occurs early in life.

Timing of surgery in aortic stenosis

In adults with valvular stenosis, the importance of prompt aortic valve replacement once symptoms occur is well known. The operative mortality for aortic valve replacement has improved dramatically over the past 4 decades and remains the only effective therapy for severe symptomatic aortic stenosis. Aortic valve replacement in patients with left ventricular dysfunction has a high operative mortality, although those patients who do not undergo surgery at all have an even worse outcome. While issues to consider include the presence or absence of coronary artery disease and expected hemodynamics of the prosthetic valve compared with the native valve, when in doubt, one should err on the side of surgical intervention. Elderly age is not a contraindication to aortic valve replacement for severe symptomatic aortic stenosis, although there is a higher prevalence of comorbid disease and higher operative mortality. Life expectancy is significantly prolonged and quality of life is significantly improved in the elderly who survive surgery. Indications for surgery in asymptomatic patients are controversial. We do not recommend valve replacement in asymptomatic patients at this time due to the known risks of surgery and a prosthetic valve and the lack of evidence for benefit of early surgery. Patients undergoing coronary bypass surgery should be considered for concomitant aortic valve surgery for moderate aortic stenosis that is expected to progress to severe stenosis in less than 5 years.