Perspective on valvular heart disease: an update

Prosthesis-patient mismatch affects late survival after valve surgery for severe aortic stenosis

BACKGROUND

The effect of prosthesis-patient mismatch (PPM) on late survival after aortic valve replacement (AVR) in patient with symptomatic severe aortic stenosis (AS) remains unclear. Also, late follow-up in previous studies is confined to only one decade. We aimed to determine the effect of PPM on late survival after isolated AVR for symptomatic severe AS during 25 years of follow-up.

METHODS

In this retrospective cohort study, Kaplan-Meier survival analysis was performed to determine late survival in 404 consecutive patients with moderate PPM (N.=86), severe (N.=11), or no/mild PPM (N.=307) after isolated AVR for symptomatic severe AS during a mean follow-up of 25.0±2.9 years. Moderate, severe, and no/mild PPM were defined as indexed effective orifice area of >0.65≤0.85, ≤0.65, and >0.85 cm2/m2, respectively. Multivariable analysis was performed to identify possible independent predictors of decreased late survival, including moderate or severe PPM.

RESULTS

Late survival of patients with severe PPM was worse in comparison with those with no/mild PPM: 7.4±2.6 (95% confidence interval 2.2-12.5) vs. 13.6±0.5 (95% confidence interval 12.6-14.6) years, respectively; P=0.020. Late survival of patients with moderate PPM was similar to those with no/mild PPM. Severe PPM was an independent predictor of decreased late survival: hazards ratio 4.002 (95% confidence interval 1.869-8.569); P<0.001. Moderate PPM was not an independent predictor of decreased late survival.

CONCLUSIONS

Severe PPM was independently associated with decreased late survival after isolated AVR for symptomatic severe AS during a mean follow-up of 25.0±2.9 years. Therefore, severe PPM should be prevented as much as possible.

Reoperative Mitral Surgery Versus Transcatheter Mitral Valve Replacement: A Systematic Review

Bioprosthetic mitral structural valve degeneration and failed mitral valve repair (MVr) have traditionally been treated with reoperative mitral valve surgery. Transcatheter mitral valve-in-valve (MVIV) and valve-in-ring (MVIR) replacement are now feasible, but data comparing these approaches are lacking. We sought to compare the outcomes of (1) reoperative mitral valve replacement (redo-MVR) and MVIV for structural valve degeneration, and (2) reoperative mitral valve repair (redo-MVr) or MVR and MVIR for failed MVr. A literature search of PubMed, Embase, and the Cochrane Library was conducted up to July 31, 2020. Thirty-two studies involving 25 832 patients were included. Redo-MVR was required in ≈35% of patients after index surgery at 10 years, with 5% to 15% 30-day mortality. MVIV resulted in >95% procedural success with 30-day and 1-year mortality of 0% to 8% and 11% to 16%, respectively. Recognized complications included left ventricular outflow tract obstruction (0%-6%), valve migration (0%-9%), and residual regurgitation (0%-6%). Comparisons of redo-MVR and MVIV showed no statistically significant differences in mortality (11.3% versus 11.9% at 1 year, P=0.92), albeit higher rates of major bleeding and arrhythmias with redo-MVR. MVIR resulted in 0% to 34% mortality at 1 year, whereas both redo-MVr and MVR for failed repairs were performed with minimal mortality and durable long-term results. MVIV is therefore a viable alternative to redo-MVR for structural valve degeneration, whereas redo-MVr or redo-MVR is preferred for failed MVr given the suboptimal results with MVIR. However, not all patients will be candidates for MVIV/MVIR because anatomical restrictions may preclude transcatheter options from adequately addressing the underlying pathology.

Evolving new concepts in the assessment of aortic stenosis

Echocardiography has been pivotal in evaluating aortic stenosis (AS) over the past several decades. Recent experience has shown a wide spectrum in the clinical presentation of AS. A better understanding of the underlying hemodynamic principles has resulted in emergence of new subtypes of AS. New treatment modalities have also been introduced, requiring precise evaluation of aortic valve (AV) pathology for implementation of these therapies. This review will discuss new concepts and indices in the use of echocardiography in patients with AS. Specifically, we will address the hemodynamic characteristics, clinical presentation, and management of normal-flow, high-gradient; paradoxical low-flow, low-gradient; and classical low-flow, low-gradient aortic stenoses.

Approach to the analysis of cardiac valve prostheses as surgical pathology or autopsy specimens

Pathologists are likely to encounter substitute heart valves with increasing frequency. Informed evaluation of such valves provides valuable information that contributes to both patient care and our understanding of the pathobiology of host interactions with mechanical devices. This article summarizes the most important considerations underlying such analyses-including valve identification, common morphologic features and modes of failure, technical details of evaluation, and potential pitfalls.

Percutaneous Transcatheter Aortic Valve Implantation — The Evolution, Current Status and the Future

Aortic valve stenosis (AS) will become more common as the population ages. Once symptoms occur, the prognosis is poor. Aortic valve replacement (AVR) has been the standard of care, improving symptoms and prolonging survival. A significant proportion of patients, however, do not undergo AVR due to increased surgical-risk. The technology of transcatheter aortic valve implantation (TAVI) emerged in 2002 and offered some of these patients an alternative therapy. A randomised (PARTNER) trial has shown that TAVI (using the Edwards-Sapien transcatheter heart valve) was superior to medical therapy (including balloon aortic valvuloplasty) in inoperable patients with a significant reduction in all-cause mortality at one year. For high surgical-risk patients, TAVI demonstrated non-inferiority to open AVR, with similar all-cause mortality at one year. Currently two devices, the Edwards-Sapien and the CoreValve transcatheter heart valves, are in clinical use and are undergoing further trials. Device improvements will be required to enhance procedural success and safety and longer term data would be required to understand the longevity of these valves. Further trial data would be required to compare TAVI and open AVR in moderate surgical-risk patients if this technology were to become a more common therapy.

Valve prosthesis-patient mismatch (VP-PM): a long-term perspective

The concept/phenomenon of valve prosthesis/patient mismatch (VP-PM), described in 1978, has stood the test of time. From that time to 2011, VP-PM has received a great deal of attention but studies have come to varying conclusions. This is largely because of the determination of prosthetic heart valve area [called effective orifice area index (EOAi)] by projection rather than by actual measurement, variable criteria to assess severity of EOAi and the timing of determination of EOAi. All prosthetic heart valves have some degree of VP-PM which must be placed in a proper clinical perspective. This can be done by determining its effects on function and outcomes. For mortality one needs to focus especially on severe/critical degree of VP-PM and determine the cause of death was due to VP-PM. For the period "beyond 2011" a road map is suggested that will have uniformity of assessment of VP-PM and a focusing on the important goals of VP-PM.

Quality of life after aortic valve replacement

Understanding the quality of life after aortic valve replacement has become increasingly important. As aortic valve replacement numbers increase, more patients, physicians and families are affected by the subsequent quality of life. Quality of life information can inform the decision to perform aortic valve replacement and the selection of replacement valve. When reviewing quality of life results, it is important to realize that the findings are affected by the selection and quality of instruments, as many studies have not used valid or reliable instruments. Studies have shown that aortic valve replacement appears to significantly improve the quality of life of survivors, including those older than 70 years of age and even decades after the procedure, quality of life remains high. Studies have suggested that the elderly may gain as much quality of life benefit as younger patients. No consistent differences in resulting total quality of life have been observed between mechanical and bioprosthetic valves. Only one study showed some quality of life benefits of pulmonary autograft over mechanical valves. It is unclear whether minimally invasive aortic valve replacements confer better quality of life than standard aortic valve replacements. While existing quality of life studies have provided important information, more studies are needed especially as valve technology and operative techniques continue to improve. Future studies should endeavor to use validated general and disease-specific instruments and quantify the effects of demographics, preoperative clinical conditions and intraoperative variables on quality of life outcomes.

Valvular heart disease: a century of progress

The 20th century witnessed amazing advances in the diagnosis and treatment of valvular heart disease. The advances and our hopes for future progress are described.

Influence of completely supra-annular placement of bioprostheses on exercise hemodynamics in patients with a small aortic annulus

OBJECTIVE

Aortic valve replacement in patients with a small aortic annulus is often associated with increased pressure gradients. For this reason, prostheses for completely supra-annular placement have been developed. To evaluate the potential benefit of this design, the present study compared the effectiveness of 1 intra-supra-annular bioprosthesis and 3 completely supra-annular bioprostheses in patients with an aortic annulus diameter of 23 mm or less.

METHODS

Between August 2000 and December 2004, each of 192 patients requiring aortic valve replacement with an intraoperatively measured aortic annulus diameter of 23 mm or less received one of the following bioprostheses: the stented bovine Sorin Soprano bioprosthesis (n = 28) (Sorin Group, Saluggia, Italy), the Carpentier-Edwards Perimount bioprosthesis (n = 50) (Edwards Lifesciences, Irvine, Calif), the Carpentier-Edwards Perimount Magna bioprosthesis (n = 70) (Edwards Lifesciences), or the stented porcine Medtronic Mosaic (n = 44) (Medtronic Inc, Minneapolis, Minn) bioprosthesis. After 6 months, hemodynamic data at rest and during exercise were obtained by echocardiography in 142 patients.

RESULTS

The pericardial valves showed lower mean systolic pressure gradients, larger effective orifice areas and indices, and superior effective orifice fractions than did the porcine valve (P < .05) (Carpentier-Edwards Perimount: 10.9 +/- 3.6 mm Hg, 1.59 +/- 0.41 cm2, 0.9 +/- 0.25 cm2/m2, 41.9% +/- 9.6%; Carpentier-Edwards Perimount Magna 10.1 +/- 3.8 mm Hg, 1.64 +/- 0.38 cm2, 0.93 +/- 0.22 cm2/m2, 45.1% +/- 10.2%; Sorin Soprano 13.5 +/- 5.0 mm Hg, 1.64 +/- 0.32 cm2, 0.92 +/- 0.15 cm2/m2, 45.8% +/- 9.0%; vs Medtronic Mosaic 15.5 +/- 5.2 mm Hg, 1.31 +/- 0.42 cm2, 0.75 +/- 0.24 cm2/m2, 35.2% +/- 10.0%, respectively). The lowest mean systolic pressure gradients were found after the implantation of the Carpentier-Edwards Perimount Magna. Effective orifice areas, indices, and fractions of the pericardial valves did not show significant differences.

CONCLUSIONS

In patients with small aortic roots, transvalvular gradients and effective orifice area showed a tendency to superior results in pericardial valves compared with the porcine bioprosthesis. However, the completely supra-annular design does not necessarily lead to superior hemodynamic results compared with the intra-supra-annular position.

Quantification of aortic valve stenosis in MRI—comparison of steady-state free precession and fast low-angle shot sequences

We compared two different magnetic resonance (MR) sequences [steady-state free precession (SSFP) and gradient echo fast low-angle shot (FLASH)] for the assessment of aortic valve areas in aortic stenosis using transesophageal echocardiography (TEE) as the standard of reference. Thirty-two patients with known aortic stenosis underwent MR (1.5 T) using a cine SSFP sequence and a cine FLASH sequence. Planimetry was performed in cross-sectional images and compared to the results of the TEE. In seven patients the grade of stenosis was additionally assessed by invasive cardiac catheterization (ICC). The mean aortic valve area measured by TEE was 0.97+/-0.19 mm(2), 1.00+/-0.25 mm(2) for SSFP and 1.25+/-0.23 mm(2) based on FLASH images. The mean difference between the valve areas assessed based on SSFP and TEE images was 0.15+/-0.13 cm(2) (FLASH vs TEE: 0.29+/-0.17 cm(2)). Bland-Altman analysis demonstrated that measurements using FLASH images overestimated the aortic valve area compared to TEE. Comparing ICC with MRI and TEE, only a weak to moderate correlation was found (ICC vs TEE: R=0.52, p=0.22; ICC vs SSFP: R=0.20, p=0.65; ICC vs FLASH: R=0.16, p=0.70). Measurements of the aortic valve area based on SSFP images correlate better with TEE compared to FLASH images.

Projected valve area at normal flow rate improves the assessment of stenosis severity in patients with low-flow, low-gradient aortic stenosis: the multicenter TOPAS (Truly or Pseudo-Severe Aortic Stenosis) study

BACKGROUND

We sought to investigate the use of a new parameter, the projected effective orifice area (EOAproj) at normal transvalvular flow rate (250 mL/s), to better differentiate between truly severe (TS) and pseudo-severe (PS) aortic stenosis (AS) during dobutamine stress echocardiography (DSE). Changes in various parameters of stenosis severity have been used to differentiate between TS and PS AS during DSE. However, the magnitude of these changes lacks standardization because they are dependent on the variable magnitude of the transvalvular flow change occurring during DSE.

METHODS AND RESULTS

The use of EOAproj to differentiate TS from PS AS was investigated in an in vitro model and in 23 patients with low-flow AS (indexed EOA <0.6 cm2/m2, left ventricular ejection fraction < or =40%) undergoing DSE and subsequent aortic valve replacement. For an individual valve, EOA was plotted against transvalvular flow (Q) at each dobutamine stage, and valve compliance (VC) was derived as the slope of the regression line fitted to the EOA versus Q plot; EOAproj was calculated as EOAproj=EOArest+VCx(250-Q(rest)), where EOArest and Q(rest) are the EOA and Q at rest. Classification between TS and PS was based on either response to flow increase (in vitro) or visual inspection at surgery (in vivo). EOAproj was the most accurate parameter in differentiating between TS and PS both in vitro and in vivo. In vivo, 15 of 23 patients (65%) had TS and 8 of 23 (35%) had PS. The percentage of correct classification was 83% for EOAproj and 91% for indexed EOAproj compared with percentages of 61% to 74% for the other echocardiographic parameters usually used for this purpose.

CONCLUSIONS

EOAproj provides a standardized evaluation of AS severity with DSE and improves the diagnostic accuracy for distinguishing TS and PS AS in patients with low-flow, low-gradient AS.

Rest and Exercise Performance of the Medtronic Advantage Bileaflet Valve in the Aortic Position

BACKGROUND

The aim of the study was to evaluate rest and exercise performance and left ventricular mass regression of the Medtronic Advantage (Medtronic, Inc, Minneapolis, MN) prosthesis in the aortic position at 1 year at a single center as part of a multicenter, prospective clinical trial.

METHODS

Between May 2002 and June 2003, 63 consecutive patients underwent aortic valve replacement with a Medtronic Advantage prosthesis (84.1% male; mean age, 56.0 +/- 9.7 years; ejection fraction, 56.5 +/- 15.8%). Valve lesions were stenosis (n = 20), mixed (n = 34), and insufficiency (n = 9). Concomitant procedures were performed in 34.9%. Follow-up was 100% complete. Echocardiographic data were obtained early postoperatively and at 1 year, combined with stress echocardiography by treadmill. Mean pressure gradients, stroke volume, and left ventricular mass were determined by echocardiography. Data are presented as mean +/- standard deviation.

RESULTS

Operative mortality was 0%. Valve-related complications were observed in 2 patients (endocarditis, n = 1; thromboembolic event, n = 1). There was no case of antithromboembolic hemorrhage, prosthesis-related explant, or reoperation. One patient showed moderate paravalvular regurgitation. Mean pressure gradients 1 year postoperatively ranged from 6.3 to 11.0 mm Hg across all valve sizes. Left ventricular mass regression at 1 year was 18.4% across all valve sizes (p < 0.001). No severe patient-prosthesis mismatch (effective orifice area index < or = 0.65 cm2/m2) could be observed.

CONCLUSIONS

After 1 year, the Medtronic Advantage valve shows comparable transvalvular mean pressure gradients across the valve sizes used during rest and exercise. This is accompanied by a significant left ventricular mass regression, an important indicator for long-term survival.

Quantification of aortic valve area and left ventricular muscle mass in healthy subjects and patients with symptomatic aortic valve stenosis by MRI

MRI allows visualization and planimetry of the aortic valve orifice and accurate determination of left ventricular muscle mass, which are important parameters in aortic stenosis. In contrast to invasive methods, MRI planimetry of the aortic valve area (AVA) is flow independent. AVA is usually indexed to body surface area. Left ventricular muscle mass is dependent on weight and height in healthy individuals. We studied AVA, left ventricular muscle mass (LMM) and ejection fraction (EF) in 100 healthy individuals and in patients with symptomatic aortic valve stenosis (AS). All were examined by MRI (1.5 Tesla Siemens Sonate) and the AVA was visualized in segmented 2D flash sequences and planimetry of the performed AVA was manually. The aortic valve area in healthy individuals was 3.9+/-0.7 cm(2), and the LMM was 99+/-27 g. In a correlation analysis, the strongest correlation of AVA was to height (r=0.75, p<0.001) and for LMM to weight (r=0.64, p<0.001). In a multiple regression analysis, the expected AVA for healthy subjects can be predicted using body height: AVA=-2.64+0.04 x(height in cm) -0.47 x w (w=0 for man, w=1 for female).In patients with aortic valve stenosis, AVA was 1.0+/-0.35 cm(2), in correlation to cath lab r=0.72, and LMM was 172+/-56 g. We compared the AS patients results with the data of the healthy subjects, where the reduction of the AVA was 28+/-10% of the expected normal value, while LMM was 42% higher in patients with AS. There was no correlation to height, weight or BSA in patients with AS. With cardiac MRI, planimetry of AVA for normal subjects and patients with AS offered a simple, fast and non-invasive method to quantify AVA. In addition LMM and EF could be determined. The strong correlation between height and AVA documented in normal subjects offered the opportunity to integrate this relation between expected valve area and definitive orifice in determining the disease of the aortic valve for the individual patient. With diagnostic MRI in patients with AS, invasive measurements of the systolic transvalvular gradient does not seem to be necessary.

Exercise hemodynamics of bovine versus porcine bioprostheses: a prospective randomized comparison of the mosaic and perimount aortic valves

OBJECTIVE

This prospective randomized study compares a porcine with a bovine bioprosthesis in the aortic position with regard to hemodynamic performance during exercise.

METHODS

Between August of 2000 and December of 2002, 136 patients underwent aortic valve replacement with the porcine Medtronic Mosaic (n = 66) or the bovine Carpentier-Edwards Perimount (n = 70) bioprosthesis. Transthoracic echocardiography was performed to assess hemodynamic and dimensional data preoperatively and 10 months postoperatively; the latter follow-up included stress echocardiography with treadmill exercise.

RESULTS

At rest and during exercise (25 and 50 W), there was a significant difference in mean pressure gradient between the bovine and the porcine valves with labeled sizes 21 and 23, with superiority of the Perimount prosthesis. There was no difference in effective orifice area and incidence of patient-prosthesis mismatch among all sizes. The left ventricular mass index decreased significantly within 10 months postoperatively in the size 23 bovine group and the size 25 porcine group.

CONCLUSIONS

Our data show a significant superiority of pressure gradients for the bovine bioprosthesis, especially with small valve sizes, when compared with the porcine device, which is more distinctive during exercise.

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

OBJECTIVES

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Comparison of outcomes after aortic valve replacement with a mechanical valve or a bioprosthesis using microsimulation

BACKGROUND

Mechanical valves and bioprostheses are widely used for aortic valve replacement. Though previous randomised studies indicate that there is no important difference in outcome after implantation with either type of valve, knowledge of outcomes after aortic valve replacement is incomplete.

OBJECTIVE

To predict age and sex specific outcomes of patients after aortic valve replacement with bileaflet mechanical valves and stented porcine bioprostheses, and to provide evidence based support for the choice of prosthesis.

METHODS

Meta-analysis of published results of primary aortic valve replacement with bileaflet mechanical prostheses (nine reports, 4274 patients, and 25,726 patient-years) and stented porcine bioprostheses (13 reports, 9007 patients, and 54,151 patient-years) was used to estimate the annual risks of postoperative valve related events and their outcomes. These estimates were entered into a microsimulation model, which was employed to calculate age and sex specific outcomes after aortic valve replacement.

RESULTS

Life expectancy (LE) and event-free life expectancy (EFLE) for a 65 year old man after implantation with a mechanical valve or a bioprosthesis were 10.4 and 10.7 years and 7.7 and 8.4 years, respectively. The lifetime risk of at least one valve related event for a mechanical valve was 48%, and for a bioprosthesis, 44%. For LE and EFLE, the age crossover point between the two valve types was 59 and 60 years, respectively.

CONCLUSIONS

Meta-analysis based microsimulation provides insight into the long term outcome after aortic valve replacement and suggests that the currently recommended age threshold for implanting a bioprosthesis could be lowered further.

Role of echocardiography in the diagnosis and treatment of patients with aortic stenosis

PURPOSE OF REVIEW

Echocardiographic assessment plays a major role in the evaluation of aortic stenosis (AS). Because of its proven accuracy, ease of applicability, and safety, it is replacing cardiac catheterization for the assessment of AS in many centers.

RECENT FINDINGS

In this review, we discuss the basic principles of echocardiographic assessment of AS and clinically challenging scenarios including AS with low cardiac output state or other structural heart disease. Dobutamine stress echocardiography is a useful tool for assessing low cardiac output AS. The role of transesophageal echocardiography in the evaluation of AS is also reviewed.

SUMMARY

Echocardiographic techniques provide critical information in the assessment of patients with known or suspected AS and guide decision-making regarding the appropriateness of valve replacement.

Functional changes in coronary microcirculation after valve replacement in patients with aortic stenosis

BACKGROUND

Increased extravascular compression and reduced diastolic perfusion time (DPT), rather than vascular remodeling, influence coronary microcirculatory dysfunction in aortic stenosis (AS). However, alterations after aortic valve replacement (AVR) remain unclear. The aim of the present study was to quantify changes in transmural perfusion and coronary vasodilator reserve (CVR), a measure of microcirculatory function, after AVR and determine the relative contribution of left ventricular mass (LVM) regression, change in aortic valve area (AVA), and DPT.

METHODS AND RESULTS

Twenty-two patients with AS were studied before and 1 year after AVR using echocardiography to measure AVA, cardiovascular magnetic resonance to assess LVM, and positron emission tomography to quantify resting and hyperemic myocardial blood flow (MBF) and CVR. Regression of LVM occurred in all patients (from 129+/-30 to 94+/-24 g/m2; P<0.0001), and there was a significant reduction in resting MBF and increase in CVR corrected for rate-pressure product after AVR, although these changes displayed marked heterogeneity. Regression of LVM was linearly related to change in resting total LV blood flow but not CVR. Increase in hyperemic MBF and CVR transmurally was directly related to the increase in AVA after AVR. A significant relationship existed between the change in hyperemic DPT (1.0+/-4.7 s/min [range, 6.8 to 9.6]) and change in transmural CVR (y=0.08x+0.18; r=0.44; P=0.04).

CONCLUSIONS

Changes in coronary microcirculatory function in patients with AS after AVR are not directly dependent on regression of LVM. Reduced extravascular compression and increased DPT are proposed as the main mechanisms for improvement in MBF and CVR after AVR.

Prophylactic aortic valve replacement in older patients for mild aortic stenosis during coronary bypass surgery

Coronary bypass surgery (CBS) is performed in many older patients who frequently also have mild calcific aortic stenosis. It is important that a correct assessment of the severity of aortic stenosis is done by calculating the aortic valve area. Mild aortic stenosis is aortic valve area >1.5 cm(2), >0.9 cm(2)/m(2); severe aortic stenosis is aortic valve area < or =1.0 cm(2), < or =0.6 cm(2)/m(2). Patients who have severe aortic stenosis should have aortic valve replacement (AVR) at the time of CBS. Patients with mild aortic stenosis should not have AVR simultaneously with CBS because: 1) patients having AVR+CBS have a higher operative and 10-year mortality; 2) prosthetic heart valves are associated with a complication rate of 2%-6% per year; and 3) only about 12% of patients with mild aortic stenosis will have developed severe aortic stenosis in 10 years. Performing AVR for mild aortic stenosis at the time of CBS will probably result in 91 unnecessary AVRs and 29 excess deaths in 10 years.

Choice of prosthetic heart valve for adult patients

This review summarizes the major long-term (> or =10 to 15 years) patient outcomes after insertion of many Food and Drug Administration approved prosthetic heart valves (PHV). Mechanical PHV was associated with a better survival (p < 0.02) at 15 years after aortic valve replacement (AVR) than with a bioprosthesis in the Department of Veterans Affairs (DVA) trial. In both the DVA and the Edinburgh Heart Valve trials, bioprosthesis were associated with structural valve deterioration (SVD) (mitral valve replacement [MVR] > AVR) and, therefore, for replacement of the PHV. Thromboembolism and bleeding rate were higher with mechanical PHV. Mortality after AVR and MVR is high at 10 to 15 years because of the associated comorbid conditions and older age of patients. Outcomes with "new" good valves are similar to that with "older" good valves. Complication rates of thromboembolism, bleeding, endocarditis, and leak vary widely; the rates of these complications are not different among different mechanical PHV and among different bioprosthetic PHV. Structural valve deterioration is rare with mechanical PHV. Structural valve deterioration of bioprosthesis after MVR is higher than after AVR; after AVR, homografts and bioprosthesis have similar rates of SVD. The exact rate of SVD of the pulmonary autograft is uncertain. Valve prosthesis-patient mismatch is clinically important when it is severe and in selected patients when it is moderate. Bioprosthesis have a low rate of SVD in the older patient and, thus, are the PHV of choice for AVR in patients > or =60 to 65 years of age and for MVR in patients > or =65 to 70 years of age; in younger patients mechanical valves are the PHV of choice. In individual patients there may be exceptions to these general rules.

Discrepancies between catheter and Doppler estimates of valve effective orifice area can be predicted from the pressure recovery phenomenon: practical implications with regard to quantification of aortic stenosis severity

OBJECTIVES

We sought to obtain more coherent evaluations of aortic stenosis severity.

BACKGROUND

The valve effective orifice area (EOA) is routinely used to assess aortic stenosis severity. However, there are often discrepancies between measurements of EOA by Doppler echocardiography (EOA(Dop)) and those by a catheter (EOA(cath)). We hypothesized that these discrepancies might be due to the influence of pressure recovery.

METHODS

The relationship between EOA(cath) and EOA(Dop) was studied as follows: 1) in an in vitro model measuring the effects of different flow rates and aortic diameters on two fixed stenoses and seven bioprostheses; 2) in an animal model of supravalvular aortic stenosis (14 pigs); and 3) based on catheterization data from 37 patients studied by Schöbel et al.

RESULTS

Pooling of in vitro, animal, and patient data showed a good correlation (r = 0.97) between EOA(cath) (range 0.3 to 2.3 cm(2)) and EOA(Dop) (range 0.2 to 1.7 cm(2)), but EOA(cath) systematically overestimated EOA(Dop) (24 +/- 17% [mean +/- SD]). However, when the energy loss coefficient (ELCo) was calculated from EOA(Dop) and aortic cross-sectional area (A(A)) to account for pressure recovery, a similar correlation (r = 0.97) with EOA(cath) was observed, but the previously noted overestimation was no longer present.

CONCLUSIONS

Discrepancies between EOA(cath) and EOA(Dop) are largely due to the pressure recovery phenomenon and can be reconciled by calculating ELCo from the echocardiogram. Thus, ELCo and EOA(cath) are equivalent indexes representing the net energy loss due to stenosis and probably are the most appropriate for quantifying aortic stenosis severity.

Mechanisms of coronary microcirculatory dysfunction in patients with aortic stenosis and angiographically normal coronary arteries

BACKGROUND

Development of left ventricular hypertrophy in aortic stenosis (AS) is accompanied by coronary microcirculatory dysfunction, demonstrated by an impaired coronary vasodilator reserve (CVR). However, evidence for regional abnormalities in myocardial blood flow (MBF) and the potential mechanisms is limited. The aims of this study were to quantitatively demonstrate differences in subendocardial and subepicardial microcirculation and to investigate the relative contribution of myocyte hypertrophy, hemodynamic load, severity of AS, and coronary perfusion to impairment in microcirculatory function.

METHODS AND RESULTS

Twenty patients with isolated moderate to severe AS were studied using echocardiography to assess severity of AS, cardiovascular magnetic resonance to measure left ventricular mass (LVM), and PET to quantify resting and hyperemic (dipyridamole 0.56 mg/kg) MBF and CVR in both the subendocardium and subepicardium. In the patients with most severe AS (n=15), the subendocardial to subepicardial MBF ratio decreased from 1.14+/-7 at rest to 0.92+/-7 during hyperemia (P<0.005), and subendocardial CVR (1.43+/-3) was lower than subepicardial CVR (1.78+/-35; P=0.01). Resting total LV blood flow was linearly related to LVM, whereas CVR was not. Increase of total LV blood flow during hyperemia (mean value, 89.6+/-6%; range, 17% to 233%) was linearly related to aortic valve area. The decrease in CVR was related to severity of AS, increase in hemodynamic load, and reduction in diastolic perfusion time, particularly in the subendocardium.

CONCLUSIONS

CVR was more severely impaired in the subendocardium in patients with LVH attributable to severe AS. Severity of impairment was related to aortic valve area, hemodynamic load imposed, and diastolic perfusion rather than to LVM.

Hemodynamic and clinical impact of prosthesis-patient mismatch in the aortic valve position and its prevention

Prosthesis-patient mismatch is present when the effective orifice area of the inserted prosthetic valve is less than that of a normal human valve. This is a frequent problem in patients undergoing aortic valve replacement, and its main hemodynamic consequence is the generation of high transvalvular gradients through normally functioning prosthetic valves. The purposes of this report are to present an update on the concept of aortic prosthesis-patient mismatch and to review the present knowledge with regard to its impact on hemodynamic status, functional capacity, morbidity and mortality. Also, we propose a simple approach for the prevention and clinical management of this phenomenon because it can be largely avoided if certain simple factors are taken into consideration before the operation.

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

BACKGROUND

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

METHODS AND RESULTS

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

CONCLUSIONS

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

Usefulness of the echocardiographic velocity ratio for detection of significant aortic stenosis

In this study, which included 56 patients with aortic stenosis, the predictive value of the fractional shortening velocity ratio was evaluated. This Doppler index allowed detection of significant aortic stenosis (0.53 cm2/m2), with a positive predictive value of 93% and a negative predictive value of 92% for a cutoff value of 0.8.

Valvular and coronary heart disease. When is it time for surgical referral?

Decisions about when to refer patients for cardiac surgery remain dynamic in the face of rapidly advancing technology. Coexisting health problems obviously play an important role, as do the natural history of the cardiovascular disorder, the indications for surgery, and the risks associated with the operative procedure. Nonetheless, many patients can be offered the possibility of improved cardiovascular function and survival through cardiac interventions.

Risk and predictors for pregnancy-related complications in women with heart disease

BACKGROUND

The physiological changes of pregnancy can result in cardiovascular complications in the mother, which in turn may have fetal implications. Prior studies have focused on specific cardiac lesions or identified univariate predictors. There is a need to refine the risk stratification of women with heart disease so they can receive appropriate obstetrical counseling and care.

METHODS AND RESULTS

We examined the outcomes of 221 women with heart disease who underwent 276 pregnancies and received their obstetrical care at three Toronto hospitals from 1986 through 1994. Those who underwent therapeutic abortions were excluded. Among the study participants, there were 24 miscarriages and 252 completed pregnancies (pregnancies not ending in miscarriage). Maternal heart failure, arrhythmia, or stroke occurred in 45 completed pregnancies (18%). There were no maternal deaths. Poor maternal functional class or cyanosis, myocardial dysfunction, left heart obstruction, prior arrhythmia, and prior cardiac events were predictive of maternal cardiac complications. These predictors were incorporated into a point score that can be used to estimate the probability of a cardiac complication in the mother. The rate of cardiac complications for a patient with 0, 1, and >1 of the above factors was 3%, 30%, and 66%, respectively. Neonatal complications occurred in 42 completed pregnancies (17%). Neonatal events included death (2), respiratory distress syndrome (16), intraventricular hemorrhage (2), premature birth (35), and small-for-gestational-age birth weight (14). Poor maternal functional class or cyanosis was predictive of neonatal events.

CONCLUSIONS

Despite low maternal and neonatal mortality, pregnancy in women with heart disease is associated with significant cardiac and neonatal morbidity. The probability of maternal cardiac or neonatal events can be predicted from baseline characteristics of the mother.

Actuarial outcome after catheter balloon commissurotomy in patients with mitral stenosis

BACKGROUND

The goal of the present study was to determine the intermediate-term survival and the independent predictors of survival and event-free survival for patients who undergo catheter balloon commissurotomy (CBC).

METHODS AND RESULTS

CBC for the treatment of mitral stenosis was performed in 132 patients from 1986 through 1994. The use of CBC increased the mitral valve area (MVA) from 1.0 +/- 0.3 to 1.9 +/- 0.6 cm2 (P < .001). There were six early deaths (4.5%) up to 1 month after CBC ("hospital" deaths). In the past 4.5 years, there have been no hospital deaths. Four late deaths occurred after elective mitral valve replacement (MVR). Actuarial 7-year survival was 95 +/- 1%; when mortality after MVR is included, 7-year survival was 83 +/- 6%. Actuarial 1-, 3-, 5-, and 7-year event-free survival (survival without MVR or repeat CBC) was 80 +/- 4%, 77 +/- 4%, 65 +/- 6%, and 65 +/- 6%. On multivariate analysis, the only two independent predictors (both after CBC) of 7-year event-free survival were MVA of > or = 1.5 versus < 1.5 cm2 (75 +/- 7% versus 32 +/- 12%) and mean pulmonary artery wedge pressure of < or = 18 versus > 18 mm Hg (84 +/- 6% versus 38 +/- 11%) (P < .001 for both). Patients with MVA of > or = 1.5 cm2 (n = 96) could be further subdivided into high- and low-risk subgroups for 7-year event-free survival by two post-CBC variables: mean pulmonary artery wedge pressure of < or = 18 versus > 18 mm Hg (90 +/- 6% versus 48 +/- 14%) (P = .0002) and cardiac index of > or = 2.5 versus < 2.5 L.min-1.m-2 (82 +/- 8% versus 61 +/- 13%) (P = .004). Patients with post-CBC MVA of < 1.5 cm2 (n = 24) had no additional predictors of event-free survival. Of patients who did not undergo MVR or repeat CBC, 8% were in New York Heart Association functional class III and 92% were in class I or early class II at the last follow-up.

CONCLUSIONS

The rates for intermediate-term survival and event-free survival after CBC are very encouraging. Most patients without events were asymptomatic or minimally symptomatic. Thus, in selected patients with mitral stenosis who require an interventional procedure, CBC is the procedure of choice at centers with physicians who have experience and skill in performing this procedure.

Echocardiographic follow-up in patients with mild to moderate mitral stenosis: is a yearly examination justified?

The result of this study showed that echocardiographic and Doppler parameters in patients with mild to moderate mitral stenosis did not undergo any major changes over a relatively long observation period, reflecting the substantial stability of the valve disease process. Thus, unless such patients experience clinical deterioration, a yearly echocardiographic examination appears to be unjustified.

Utilization of echocardiography by internists and cardiologists: a comparative study

OBJECTIVE

To compare the utilization of echocardiography as a diagnostic tool by internists and cardiologists.

DESIGN

Retrospective study.

SETTING

Tertiary care university hospital.

METHODS

Indications and clinical utility of echocardiographic studies ordered by cardiologists (group A, n = 301) and internists (group B, n = 297) were compared by chart review. The two groups of patients were analyzed to determine if the studies detected new cardiac pathology and/or altered patient management.

RESULTS

The proportion of studies with abnormal results were similar in both groups (19% versus 14%, P > 0.05). The results of echocardiography, however, led to a change in management more often when the study was ordered by cardiologists (16% versus 10%, P < 0.05). A significantly greater proportion of studies were ordered for evaluation of valvular function by internists (44% versus 33%, P < 0.05). Echocardiography detected valvular abnormalities in a similar proportion of cases in groups A and B (14% versus 10%, P > 0.05). However, diagnostic yield was very poor when the study was performed in patients with suspected mitral valve prolapse in both groups. Cardiologists utilized echocardiography more often for evaluation of left ventricular function (35% versus 18%, P < 0.01) and in the setting of atherosclerotic heart disease for detecting wall motion abnormalities (14% versus 5%, P < 0.01).

CONCLUSION

Diagnostic yield of echocardiography is similar when ordered by internists and cardiologists. With the information obtained, management is altered in a slightly greater proportion of cases involving a cardiologist. This may be due to utilization of echocardiography more often for estimating left ventricular function and for detecting wall motion abnormalities by cardiologists.

An introduction to transoesophageal echocardiography: I. Basic principles

PURPOSE

The purpose of this review is to introduce the uninitiated to transoesophageal echocardiography (TEE): how it works, and what it can do. Sufficient detail is provided to serve as a reference guide to anaesthetists already using TEE in clinical practice.

SOURCE

A Medline search of English language literature up to and including August 1995 was conducted using the key words echocardiography and TEE. Reference echocardiography textbooks were also utilized in the preparation of this review.

PRINCIPLE FINDINGS

All information available from TEE is derived from either cardiac imaging or analysis of blood flow velocity using various Doppler modes. To understand the diagnostic capabilities of TEE we review clinically useful views of the heart as well as modes of cardiac imaging. Sufficient basic physics is presented to allow proper use of adjustment features on the echocardiography machine so that cardiac imaging can be optimized. Available Doppler modes are explained along with an overview of their clinical applications. Figures illustrating clinically useful views obtainable with omniplane TEE are included along with colour prints demonstrating clinical applications of colour flow Doppler.

CONCLUSION

TEE is becoming increasingly important in the management of cardiac patients for cardiac and non-cardiac surgery. An understanding of the capabilities of the technology as well as the underlying physics allows the anaesthetist to glean the most information from this valuable technique, both quantitatively and qualitatively.

Effect of Doppler echocardiography on utilization of hemodynamic cardiac catheterization in the preoperative evaluation of aortic stenosis

OBJECTIVE

To examine the use of Doppler echocardiography in preoperative assessment of aortic stenosis and to determine its effect on subsequent use of hemodynamic cardiac catheterization.

MATERIAL AND METHODS

We retrospectively reviewed a consecutive series of 574 adult patients who underwent aortic valve replacement for aortic stenosis between 1990 and 1992 at our institution. The use of Doppler echocardiography and cardiac catheterization and the predictive factors for use of hemodynamic catheterization were analyzed.

RESULTS

After Doppler echocardiography in 423 patients, invasive hemodynamic assessment of the severity of aortic stenosis was performed in only 42% (179 patients). The use of cardiac catheterization declined over time (54% in 1990, 40% in 1991, and 35% in 1992) (P = 0.003), whereas no significant change in the baseline clinical characteristics of the population or in severity of stenosis as determined by Doppler echocardiography occurred during that time. Multivariate analysis identified the following variables as independent predictors of use of cardiac catheterization after Doppler echocardiography: clinically not severe aortic stenosis, mean gradient of less than 50 mm Hg determined by Doppler echocardiography, Doppler-determined aortic valve area of more than 0.8 cm2 or not calculated, attending cardiologist not specialized in echocardiography, and earlier year of assessment.

CONCLUSION

After Doppler echocardiography, less than 50% of our patients undergoing aortic valve replacement for aortic stenosis have cardiac catheterization preoperatively. The use of cardiac catheterization after Doppler echocardiography--thus, duplication of hemodynamic assessment--declined significantly over time during the study period. Decline in the use of catheterization is related to the degree of diagnostic certainty provided by Doppler echocardiography and to the level of familiarity of the attending cardiologist with the technique.