Effect Of Aortic Valve Replacement Research Articles

Aortic valve replacement for aortic stenosis is associated with improved aortic distensibility at long-term follow-up

Aortic valve stenosis (AS) is the most frequent form of valvular heart disease. The number of studies evaluating the effect of aortic valve replacement (AVR) for AS on aortic vascular function is limited. The aim of the present study was to examine alterations in aortic distensibility in patients with AS during a 1-year follow-up after AVR. Twelve patients with severe AS who underwent AVR were prospectively examined (mean age 65 +/- 11 years, 7 men). Systolic and diastolic ascending aortic diameters (SD and DD, respectively) were recorded in M mode 3 cm above the aortic valve from a parasternal long-axis view. The SD and DD were measured at the time of maximum anterior motion of the aorta and at the start of the QRS complex, respectively. Aortic stiffness index (beta) was defined as [ln(SBP/DBP)] x DD/deltaD, where ln is the natural logarithm, SBP and DBP are the systolic and diastolic blood pressure values, respectively, and deltaD = SD - DD. As expected, aortic stenosis severity and left ventricular mass decreased significantly after AVR. Aortic diameter changes (systolic minus diastolic dimensions) progressively increased and the aortic stiffness index progressively improved to levels comparable with those of age-, sex-, and risk factor-matched controls at the 1-year assessment. Aortic valve replacement in patients with AS is associated with a progressive improvement in aortic distensibility to 1-year values similar to those of controls.

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

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

Acquired and Reversible von Willebrand Disease With High Shear Stress Aortic Valve Stenosis

Severe aortic valve stenosis is relatively more prevalent in patients with repeated bleeding episodes. The goal of the present study was to determine the effect of aortic valve replacement on von Willebrand factor levels in patients with aortic stenosis. von Willebrand factor levels were assessed by using immunoblotting electrophoresis techniques before and 1 month after surgery in 29 consecutive patients with severe aortic valve stenosis. Eight of 29 patients reported episodes of bleeding, including three episodes of major bleeding, in the 6 months before surgery. None of the patients were receiving anticoagulation therapy. Although there was no difference in platelet count before and after surgery, von Willebrand factor levels were significantly greater at 1 month after surgery (p = 0.05) when compared with preoperative values. Further, von Willebrand factor levels were significantly lower in patients with aortic valve prosthesis mismatch than in those patients without this phenomenon (p < 0.05). Electrophoresis experiments showed a deficit in large multimers of von Willebrand factor preoperatively but not postoperatively, except for in those patients with aortic valve prosthesis mismatch. In conclusion, valve replacement can result in increases in von Willebrand factor in patients with aortic valve stenosis.

540 The effect of aortic valve replacement on left ventricular deformation properties in patients with severe aortic stenosis. Ultrasound strain analysis

540 The effect of aortic valve replacement on left ventricular deformation properties in patients with severe aortic stenosis. Ultrasound strain analysis

Changes in aortic root function after valve replacement in patients with aortic stenosis

Background Aortic elastic properties are compromised in various states that induce functional and histological changes in the aortic wall. Aortic stenosis is frequent and often requires replacement of the stenotic valve. The purpose of this study was to examine the effect of aortic valve replacement on the aortic root function. Methods 31 patients, mean ± SD age 67.2 ± 9.1 years with severe aortic stenosis, who underwent aortic valve replacement with a bileaflet mechanical prosthesis, were studied. Aortic root function indices such as aortic cross-sectional compliance (CSC), aortic root distensibility (ARD), and aortic stiffness index (ASI) were calculated with the use of M-mode echocardiography in three sessions: one preoperatively (pre-op), one on day 7 postoperatively (early post-op), and one 6 months postoperatively (late post-op). Results Aortic root function deteriorated early post-op ( p < 0.001 for all) and returned towards pre-op levels late post-op ( p = NS for all). CSC changed from 2.84 ± 1.98 to 1.37 ± 0.92, and 2.30 ± 1.11 cm 2/mmHg, ARD from 2.21 ± 5.60 to 1.01 ± 0.67, and 1.79 ± 0.96 cm 2/dyne, and ASI from 9.72 ± 5.60 to 24.65 ± 19.10, and 11.51 ± 7.85, respectively. Correlations were found between early changes in some aortic root indices and the degree of aortic stenosis, denoting that aortic function deteriorated less in more severe cases of aortic stenosis. None of the late changes were related to aortic valve or left ventricular indices. Conclusions Aortic valve replacement with a mechanical valve results in a significant but transient impairment of aortic distensibility.

Aortic Stenosis and Statins

Aortic stenosis (AS) is a relatively common cause of cardiac debility and death, increasing in frequency and severity with age; indeed, AS of at least moderate severity may affect almost 8% of people ≥75 years of age.1 The natural history of AS is dependent on the myocardial response to the abnormal left ventricular pressure load caused by the stenotic valve, involving cardiomyocyte hypertrophy, hyperproduction of extracellular matrix collagen by cardiac fibroblasts, and other alterations in myocardial biology. When these changes become critically severe, symptoms develop (angina pectoris, syncope, exertional dyspnea, and other manifestations of pulmonary vascular congestion) followed predictably by cardiac death at an annual rate of 25% unless aortic valve replacement surgery is performed. See page 592 The basis of the lifesaving effect of aortic valve replacement is clear: the ventricular myocardium is unloaded, enabling myocardial remodeling toward normal, generally with recovery of normal myocardial performance.2 A more satisfactory solution than surgery would be prevention of the stenotic process itself. To achieve this goal, the pathophysiology …

Effect of aortic valve replacement on c-reactive protein in nonrheumatic aortic stenosis

Plasma levels of C-reactive protein were higher in 20 patients with bicuspid or trileaflet degenerative aortic stenosis than in 31 normal controls and in 19 patients with pure aortic regurgitation. C-reactive protein decreased from before to 6 months after aortic valve replacement for aortic stenosis. These observations suggest that aortic stenosis is an inflammatory disease.

The effect of aortic valve replacement on coronary flow reserve in patients with a normal coronary angiogram.

In patients with aortic stenosis and a normal coronary angiogram, a coronary flow reserve (CFR) is impaired. The aim of the present study was to examine the effect of aortic valve replacement (AVR) on the CFR after a long-term follow-up. 30 patients with aortic stenosis and a normal coronary angiogram were enrolled in the study. CFR measurements were made on 21 patients 123 +/- 137 days before and 497 +/- 167 days after AVR. CFR measurements were carried out according to a standard protocol, with a vasodilator stimulus dipyridamole (0.56 mg/kg for 4 min) and peak diastolic velocity measurements at 6 min. Initially, the average peak gradient of aortic stenosis was 89.5 +/- 22.4 mm Hg. After AVR, it decreased to 26.2 +/- 9 mm Hg. Left ventricular mass was significantly lower after AVR: 354.9 +/- 107.9 g versus 223.8 +/- 73.6 g (p < 0.001). The average baseline diastolic velocity measured by pulsed Doppler in the left anterior descending coronary artery amounted to 62.2 +/- 25.5 cm/s before and 40.1 +/- 13.6 cm/s after AVR. The difference was statistically significant (p < 0.01). The average diastolic velocity at maximum stress equaled 117 +/- 42.8 cm/s pre- and 91.5 +/- 34 cm/s postoperatively (p < 0.005). The calculated CFR before AVR amounted to 1.96 +/- 0.5 and increased to 2.37 +/- 0.8 postoperatively. The difference was statistically significant (p < 0.05). Prosthetic AVR is of considerable benefit concerning the CFR in patients with a normal coronary angiogram after a long-term follow-up.

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

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

The effect of aortic valve replacement on N-terminal natriuretic propeptides in patients with aortic stenosis.

Increased plasma concentrations of natriuretic peptides have been demonstrated to be associated with increased intracardiac pressure and left ventricular (LV) hypertrophy. After aortic valve replacement (AVR) in aortic stenosis patients, there is a relief of the left outflow obstruction with a substantial hemodynamic improvement. This is followed by a gradual regression of the LV hypertrophy. After AVR, reduction in LV filling pressure is expected to occur rapidly, while regression of LV hypertrophy will take place over a longer time period. On this basis we hypothesized that the plasma levels of N-terminal proatrial natriuretic peptide (NT-proANP) would be reduced early in the postoperative period, while N-terminal probrain natriuretic peptide (NT-proBNP), through its closer reflection of LV hypertrophy, would be sustained for a longer period. Two groups of patients with aortic stenosis undergoing AVR were followed for 4 and 12 months, respectively. Plasma concentrations of NT-proANP and NT-proBNP were measured before and after AVR and related to preoperative findings and changes in the aortic valve area index. Before AVR, the patients had significantly increased plasma levels of NT-proANP and NT-proBNP. After AVR, NT- proANP was decreased at 4 and 12 months but remained elevated compared with controls. N-terminal-proBNP tended to decrease, but did not change significantly. When the patients were followed for 12 months, only those with elevated preoperative pulmonary capillary wedge pressure had decreased peptide levels (NT-proANP: p = 0.017, NT-proBNP: p = 0.058). There was no regression of LV hypertrophy. The patients with the largest postoperative valve area index [1.27 (1.10-1.55) cm2/m2] had the largest reduction of NT-proBNP (47%). Those with the smallest valve area index [0.67 (0.54-0.73) cm2/m2] had no decrease in NT-proBNP. Our study suggests that a reduction in left atrial pressure is the main factor causing the change of NT-proANP level after AVR. A small prosthetic valve orifice area with a high aortic valve gradient might prevent regression of LV hypertrophy, thus representing a stimulus for increased cardiac secretion of NT-proBNP.

The effect of aortic valve replacement on coronary flow reserve in patients with hemodynamically significant aortic stenosis and normal coronary angiogram

The effect of aortic valve replacement on coronary flow reserve in patients with hemodynamically significant aortic stenosis and normal coronary angiogram

Effect of aortic valve replacement on plasma soluble P-selectin, von Willebrand factor, and fibrinogen

We measured indexes of platelet activation (soluble P-selectin), endothelial dysfunction (von Willebrand factor), and fibrinogen in 54 patients who underwent aortic valve replacement (AVR): after mechanical AVR implantation, there was a significant increase in plasma levels of soluble P-selectin and von Willebrand factor levels 3 months after surgery, with no change in mean plasma fibrinogen levels. No significant changes in measured indexes were noted in patients undergoing biologic AVR, suggesting that mechanical AVR results in abnormal endothelial damage and/or dysfunction and platelet activation, which is not apparent among patients undergoing this procedure.

The effect of aortic valve replacement on left ventricular mass assessed by echocardiography.

The aim of the study was to investigate whether aortic valve replacement (AVR) has different effects on the left ventricular mass (LVM) in patients with different types of aortic valve disease, i.e. aortic stenosis (AS), aortic regurgitation (AR), or combined disease. We studied 100 patients with AS; (n=57), AR; (n=22), and combined disease; (n=21). Each patient was evaluated before and up to 8.7 years (mean follow-up period 1.42 +/- 1.65 years) after operation by transthoracic echocardiography. LVM was calculated based on echocardiographic parameters. Following AVR, the LVM for the entire group decreased from 373 +/- 145 g to 280 +/- 102 g (P=0.0001). The AS subgroup lost 13.7 +/- 30.7% from the preoperative LVM, compared to 28.8 +/- 24.8% in the AR subgroup (P<0.05) and 23.1 +/- 33.1% in the combined subgroup. The preoperative LVM was higher among patients with AR vs. AS patients (501 +/- 173 g vs. 319 +/- 100 g respectively, P<0.05). The decrease in LVM was significantly higher in patients with preoperative AR compared to AS patients (165 +/- 150 g vs. 58 +/- 96 g, respectively, P<0.05). However, the postoperative LVM remained higher among the former. The only preoperative parameter (of the LVM formula) that was different between AR and AS patients was the left ventricular end diastolic diameter (68 +/- 11 mm vs. 51 +/- 7 mm, respectively, P<0.05). No significant differences were found in wall thickness among the groups studied. Univariate analysis showed that gender (male), type of aortic valve disease (AR vs. AS), and larger prosthetic valve diameter correlated significantly with greater decrease in postoperative LVM. In multivariate analysis comparing the above variables between AS and AR subgroups, only the patient's gender (i.e. male) was identified as an independent predictor of LVM regression. Patients with AR have a greater decline in LVM compared with patients with AS following AVR. The postoperative decline in LVM is higher among males and those with larger prosthetic valve diameter.

Immediate effect of aortic valve replacement for aortic stenosis on left ventricular diastolic chamber stiffness

Diastolic dysfunction is common after coronary artery bypass surgery, and we hypothesized that left ventricular (LV) hypertrophy associated with aortic stenosis may lead to worsening LV diastolic function after aortic valve replacement for aortic stenosis. Transesophageal echocardiographic LV images and simultaneous pulmonary arterial wedge pressures were used to define the LV diastolic pressure cross-sectional area relation before and immediately after aortic valve replacement for aortic stenosis in 14 patients. In all patients, LV diastolic chamber stiffness increased, as evidenced by a leftward shift in the LV diastolic pressure cross-sectional area relation. At comparable LV filling (pulmonary arterial wedge) pressures the mean LV end-diastolic cross-sectional area preoperatively was 17.9 ± 1.7 cm 2, but decreased by 32% after aortic valve replacement to 12.1 ± 1.2 cm 2 (p = 0.0001). In conclusion, after aortic valve replacement, diastolic chamber stiffness increased in all patients.

Immediate effects of aortic valve replacement on left ventricular function and its determinants.

Replacement of the aortic valve exposes the left ventricle to myocardial ischaemia and imposes on it abrupt changes in loading conditions and geometry. We studied the immediate changes in the left ventricular function of patients undergoing aortic valve replacement by transoesophageal echocardiography. Patients with aortic regurgitation responded to surgery with a decrease in global systolic function associated with a fall in preload. Patients with aortic stenosis showed an impairment in myocardial contractility and ventricular filling, and their global systolic function did not improve despite the marked reduction in afterload. This can be a consequence of inadequate myocardial protection and intra-operative ischaemic injury of the hypertrophic myocardium. Information provided by transoesophageal echocardiography contributes to optimal and individualized management of the period immediately after aortic valve replacement.

Immediate effects of aortic valve replacement on left ventricular function and its determinants

Replacement of the aortic valve exposes the left ventricle to myocardial ischaemia and imposes on it abrupt changes in loading conditions and geometry. We studied the immediate changes in the left ventricular function of patients undergoing aortic valve replacement by transoesophageal echocardiography. Patients with aortic regurgitation responded to surgery with a decrease in global systolic function associated with a fall in preload. Patients with aortic stenosis showed an impairment in myocardial contractility and ventricular filling, and their global systolic function did not improve despite the marked reduction in afterload. This can be a consequence of inadequate myocardial protection and intra-operative ischaemic injury of the hypertrophic myocardium. Information provided by transoesophageal echocardiography contributes to optimal and individualized management of the period immediately after aortic valve replacement.

Left ventricular mass regression early after aortic valve replacement

Regression of left ventricular hypertrophy is an important and well-recognized salutary effect of aortic valve replacement. The earliest evidence of left ventricular mass regression after aortic valve replacement and the influence of prosthesis type are not well known, and were the focus of this study. Transthoracic echocardiography was used to measure left ventricular mass index preoperatively and before discharge in 57 consecutive patients undergoing isolated aortic valve replacement (with or without coronary artery bypass grafting). Three patients were excluded from the study because of inability to obtain accurate M-mode echocardiographic images for left ventricular mass measurement preoperatively (1) or postoperatively (2). Of the remaining 54 patients, mechanical bileaflet valves were used in 19, stented tissue bioprostheses were implanted in 15, and a stentless porcine bioprosthesis was chosen for 20. Postoperative echocardiograms were obtained 4.9 +/- 2.3 days after aortic valve replacement (range, 2 to 9 days). A two-way repeated-measures analysis of variance demonstrated a significant reduction of left ventricular mass index before discharge (preoperative 141.4 +/- 45.2 g/m2, postoperative 127.5 +/- 32.8 g/m2; p = 0.0005) but no differences between prostheses. Left ventricular mass regression begins early after aortic valve replacement, probably because of reduction of transvalvular gradients and left ventricular wall stress. At least in the very early postoperative period, the type of prosthesis does not influence the extent of mass regression.

Early changes in left ventricular function after aortic valve replacement for isolated aortic stenosis

To assess the immediate effects of aortic valve replacement (AVR) for valvular aortic stenosis (AS) on left ventricular (LV) systolic and diastolic function and global hemodynamics, 17 patients with AS underwent transesophageal echocardiography combined with high-fidelity LV pressure recording and thermodilution cardiac output measurements before cardiopulmonary bypass and 0.5, 6, 12, and 20 hours after AVR. Compared with results before bypass, LV systolic function had already changed 30 minutes after AVR, and remained constant thereafter: peak LV systolic wall stress decreased (from 210 ± 60 to 130 ± 40 g·cm −2), peak rate of dimension shortening increased (from 7.3 ± 2.2 to 9.7 ± 2.1 cm·s −1), both p < 0.01. Peak segmental external power thus remained constant (16.6 ± 6.7 vs 17.7 ± 7.6 mW·c −3); p = NS. Changes in LV diastolic function and global hemodynamics were delayed. The peak rate of ventricular pressure decrease, normalized to developed endsystolic pressure, increased (from 15 ± 3.2 to 19 ± 5.2 s −1) by 6 hours. The minimal ventricular pressure of early diastole decreased (from 8.9 ±4.9 to 4.3 ± 3.7 mm Hg), the peak rate of dimension lengthening of early diastole increased (from 6.0 ± 3.0 to 8.8 ± 2.0 cm·s −1), and LV stroke volume index increased (from 24 ± 7 to 31 ± 6 ml·m −2) by 12 hours, all p < 0.01. LV incoordination, defined as the dimension changes during isovolumic periods, had also improved significantly at 20 hours. Heart rate and LV enddiastolic dimension did not change. Thus, the large step decline of LV ejection resistance when AS is corrected results in a reciprocal change in systolic force and velocity so that external power is maintained. However, global hemodynamic benefits are not achieved until diastolic function and ventricular incoordination have improved.

Changes in left ventricular filling after valve replacement for aortic stenosis.

In order to evaluate the short- and long-term effects of aortic valve replacement on the pattern of left ventricular inflow velocity, pulsed wave Doppler analysis was performed in 20 patients with isolated aortic stenosis. Complementary, left ventricular wall thickness was measured, using M-mode echocardiography. One week after operation, left ventricular wall thickness is not changed significantly. The Doppler findings suggest some improvement of left ventricular filling. Six months and 1 year postoperatively, there is a significant, but incomplete regression of left ventricular hypertrophy. Left ventricular filling improved only partially, compared to preoperatively.

Effect of aortic valve replacement for aortic stenosis on severity of mitral regurgitation

The severity of mitral regurgitation (MR) was determined by color Doppler echocardiography in 44 adult patients with severe symptomatic aortic stenosis before and after isolated aortic valve replacement. Preoperative MR was absent in 17, mild in 14, moderate in 11 and severe in 2 patients. Three to 388 (mean 58) days after surgery, 14 patients continued to have no MR. In the other 30 patients, MR decreased in 18 (60%), remained unchanged in 8 (27%) and increased in only 4 (13%). Furthermore, in 13 patients with significant (moderate or severe) MR, the severity decreased in 12 (92%). Thus, the severity of MR often decreases after aortic valve replacement for aortic stenosis.