Doppler echocardiographic assessment of the St. Jude Medical prosthetic valve in the aortic position using the continuity equation

Severe Prosthetic Mitral Valve Regurgitation Hidden by Acoustic Shadowing: The Importance of Spectral Doppler in Prosthetic Valve Assessment

•Acoustic shadowing limits Doppler evaluation in PHVs, potentially masking MR. •Spectral Doppler is an important tool to detect prosthetic MR. •TEE can supplement TTE, partially avoiding acoustic shadowing and reverberations.

Guidelines for the Evaluation of Prosthetic Valve Function With Cardiovascular Imaging: A Report From the American Society of Echocardiography Developed in Collaboration With the Society for Cardiovascular Magnetic Resonance and the Society of Cardiovascular Computed Tomography

In patients with significant cardiac valvular disease, intervention with either valve repair or valve replacement may be inevitable. Although valve repair is frequently performed, especially for mitral and tricuspid regurgitation, valve replacement remains common, particularly in adults. Diagnostic methods are often needed to assess the function of the prosthesis. Echocardiography is the first-line method for noninvasive evaluation of prosthetic valve function. The transthoracic approach is complemented with two-dimensional and three-dimensional transesophageal echocardiography for further refinement of valve morphology and function when needed. More recently, advances in computed tomography and cardiac magnetic resonance have enhanced their roles in evaluating valvular heart disease. This document offers a review of the echocardiographic techniques used and provides recommendations and general guidelines for evaluation of prosthetic valve function on the basis of the scientific literature and consensus of a panel of experts. This guideline discusses the role of advanced imaging with transesophageal echocardiography, cardiac computed tomography, and cardiac magnetic resonance in evaluating prosthetic valve structure, function, and regurgitation. It replaces the 2009 American Society of Echocardiography guideline on prosthetic valves and complements the 2019 guideline on the evaluation of valvular regurgitation after percutaneous valve repair or replacement.

The ratio of measured and reference effective orifice areas for discriminating prosthetic aortic valve obstruction

AIMS

We aimed to evaluate the efficacy of the measured effective orifice area (EOA)/reference EOA ratio in discriminating mechanical prosthetic aortic valve (PAV) obstruction.

METHODS AND RESULTS

This is a retrospective study of 193 mechanical PAV patients with an elevated mean transprosthetic pressure gradient (PG) over 20 mmHg or peak velocity over 3 m/s. Of those, 143 patients were objectively proven PAV obstruction with cardiac computed tomography or surgical inspection. The EOA was measured using the continuity equation, and the reference EOA values were obtained from previous guidelines. The measured/reference EOA ratio was significantly lower in the obstruction group (0.63 ± 0.18 vs. 0.86 ± 0.17; P < 0.001). The EOA ratio added incremental value for discriminating obstruction from the conventional parameters recommended in the guidelines. Receiver operating characteristic curve analysis revealed that the measured/reference EOA ratio discriminated PAV obstruction from those without obstruction [area under the curve (AUC), 0.840; 95% confidence interval, 0.783-0.898; P < 0.001]. A cutoff of 0.71 had 73.4% sensitivity and 82.0% specificity. The novel diagnostic algorithm adding the EOA ratio had similar accuracy to previous guideline algorithms, including reference EOA, and conventional Doppler parameters (AUC, 0.763 vs. 0.731; P = 0.309). In patients with a large PAV (≥23 mm), the novel algorithm had higher accuracy than the previous algorithm (AUC, 0.788 vs. 0.642; P = 0.019).

CONCLUSION

The ratio of measured/reference EOA adds incremental value over conventional Doppler parameters and might be helpful for distinguishing PAV obstruction.

Technical Details of Redo Aortic Valve Replacement Using St. Jude Medical Mechanical Prosthesis in a Patient with Thrombosed Aortic Mechanical Prosthesis: A Video Presentation

Current consensus guidelines of the American Heart Association and European Society of Cardiology uniformly recommend either type of prosthetic valve for patients aged between 60 and 70 years and mechanical prosthesis for patients aged less than 60 years. These recommendations are based on the results of randomized controlled trials that demonstrated no significant difference in late survival. Two of these trials compared mechanical and bioprosthetic valve models implanted in 1970s and 1980s. The other two trials included patients undergoing aortic valve replacement. Contemporary data are limited to small single-center studies

Elevated Prosthetic Valve Gradients: What to Consider When Determining an Etiology

DOPPLER echocardiography is a useful noninvasive tool for the assessment of cardiac hemodynamics. However, it is subject to limitations that can have important clinical implications, especially in the setting of valve prosthesis. Elevation in mean transvalvular gradient is a finding that has a variety of etiologies. One such etiology is the pressure-recovery (PR) phenomenon, a consequence of stream convergence and energy conversion across a narrowing, which is an artifact of Doppler echocardiographic calculations of valvular flow. The elevated gradient measured with Doppler echocardiography as a result of PR is not present on cardiac catheterization and does not represent true problematic valve hemodynamics. PR should be suspected with an elevated gradient on Doppler echocardiography with normal leaflet motion, especially in the setting of a small proximal aorta. Understanding and awareness of PR are important because PR can lead to overestimation of disease severity in the clinical setting.

The Integration of Doppler Ultrasound With Two-Dimensional Echocardiography and the Noninvasive Cardiac Hemodynamic Revolution of the 1980s

In the 1970s, as cardiac imaging matured from M-mode to two-dimensional echocardiography, investigators in Norway showed that continuous-wave Doppler ultrasonography could be used to accurately measure the mean gradient and pressure half-time for stenotic mitral valves. In the 1980s, continuous-wave Doppler was validated for measurement of the pressure gradient across stenotic aortic valves, and pulsed-wave Doppler combined with two-dimensional echocardiographic imaging was validated for noninvasive measurement of stroke volume and cardiac output. The combination of stroke volume measurement and measurement of the time-velocity integral of flow through the aortic valve was then validated as a means to accurately calculate valve area for patients with stenotic aortic valves or aortic prostheses. This integration of cardiac Doppler ultrasonography with two-dimensional echocardiographic cardiac imaging led to a revolution in noninvasive hemodynamic evaluations, which have replaced invasive hemodynamic evaluations in surgical decision making for most patients with native or prosthetic valvular stenosis.

Early hemodynamic performance of the Trifecta™ surgical bioprosthesis aortic valve in Indian patient population: 12 month outcomes of the EVEREST post-market study

BACKGROUND

Indian patients undergoing surgical aortic valve replacement (SAVR) differ from western populations with respect to aortic annulus size and valve disease morphology. The purpose of this post-market, non-randomized observational study was to evaluate the early hemodynamic performance of the Trifecta™ bioprosthesis (Abbott, previously St. Jude Medical, Minneapolis, US) in an Indian patient population.

METHODS

From January 2014 to September 2015, 100 patients (mean age 64.4 ± 7.1 years, 62% male) undergoing SAVR for valve disease (68% stenosis, 7% insufficiency, 25% mixed pathology) were enrolled across 10 centers in India. Patients implanted with a 19-27 mm Trifecta™ valve were eligible to participate and were prospectively followed for 12-months post-implantation. Echocardiographic hemodynamic performance was evaluated at pre-implant, pre-discharge and at 12-months by an independent core laboratory. Adverse events were adjudicated by the study sponsor. Functional status at 12-months was assessed according to NYHA classification. Continuous data was summarized using descriptive statistics (mean &standard deviation,) and categorical data was summarized using frequencies and percentages.

RESULT

Ninety patients (mean age 64.5, 62.2% male) completed the 12-month follow up. Significant improvements in hemodynamic valve performance were reported in 81 patients with available echocardiographic data at 12 months. Compared to baseline at 12-month follow up visit, mean effective orifice area increased from 0.75cm² to 1.61cm² (p < 0.0001), mean pressure gradient reduced to 10.42 mmHg from 51.47 mmHg (p < 0.0001), cardiac output increased from 4.46 l/min to 4.85 l/min (P 0.9254). Compared to baseline, functional status improved by ≥1 NYHA class in 75% of patients at 12 months (95% Clopper-Pearson (Exact) confidence limit [64.6%, 83.6%]). No instances of early mortality (< 30 days from index procedure) or structural valve dysfunction were reported.

CONCLUSION

In an Indian patient population, implantation of the Trifecta™ bioprosthesis is shown to be safe and associated with favorable early hemodynamic performance and improved functional status at 12 months.

TRIAL REGISTRATION

The clinical study has been registered under Clinical Trial Registry-India ( http://www.ctri.nic.in ) and registration number is CTRI/2014/02/004434 registered on 25 February 2014 retrospectively registered.

Intraoperative Transesophageal and Postoperative Transthoracic Echocardiographic Evaluation of a Mechanical Heart Valve Prosthesis Implanted at Aortic Position

OBJECTIVE

The aims of this study were to evaluate the intraoperative transesophageal echocardiographic (iTEE) characteristics and Doppler flow profile of aortic Chitra heart valve prosthesis (CHVP) under stable hemodynamic and loading conditions, and to compare and correlate the iTEE data with the postoperative transthoracic echocardiography (TTE) data obtained at 48 hours (TTE₁) and 3 months (TTE₂) after the surgery.

DESIGN

Prospective, observational study.

SETTING

University-level tertiary referral hospital.

PARTICIPANTS

Forty patients between 18 years and 65 years of age undergoing elective aortic valve replacement (AVR) using CHVP during the period January 2015 to August 2016.

INTERVENTIONS

After obtaining permission from institutional ethics committee, 40 patients undergoing elective AVR were studied prospectively. The iTEE examination was performed in the pre-cardiopulmonary bypass (CPB) and post-CPB period in all the study subjects. CHVP was subjected to iTEE two-dimensional (2D) echo, color Doppler, and spectral Doppler evaluation under stable hemodynamic and loading condition in the post-CPB period after the administration of protamine. The CHVP were re-evaluated using TTE in all the patients 48 hours after the surgery (TTE₁) and 3 months after the surgery (TTE₂). The iTEE and postoperative TTE Doppler values were compared and correlated.

MEASUREMENTS AND MAIN RESULTS

The CHVP could be imaged adequately and interrogated with Doppler in all the patients. None of the patients had restriction of occluder mobility or unstable seating of the valve. The intraoperative flow dependent (peak velocity [PV] and mean pressure gradient [MPG]) and less flow dependent (Doppler velocity index, acceleration time, acceleration time/ejection time, effective orifice area [EOA] and indexed EOA) Doppler parameters of CHVP were measured as per the American Society of Echocardiography recommendations. The PV and MPG of CHVP measured by iTEE showed no statistical difference (p > 0.05) and were in limits of agreement when compared with TTE₁ and TTE₂ data.

CONCLUSION

The iTEE features of CHVP were found compliant with the criteria set by the ASE defining normal functioning of an aortic valve prosthesis. The iTEE Doppler parameters obtained under stable loading conditions strongly predicted the postoperative values of Doppler parameters on TTE examination. The iTEE Doppler values can be used as the reference values for the postoperative follow up studies.

Successful fibrinolytic treatment of prosthetic heart valve thrombosis using streptokinase

OBJECTIVES

This study aims to evaluate the clinical outcome of fibrinolytic treatment of prosthetic valve thrombosis (PVT) with 'streptokinase' as a first line treatment for these cases.

METHODS

The study group was 20 consecutive patients (10 females) diagnosed with PVT. The protocol for streptokinase administration was either accelerated (intravenous infusion of 0.5 million IU over 30 minutes followed by 0.15 million IU/h) or conventional (intravenous infusion of 0.25 million IU over 30 minutes followed by 0.15 million IU/h). Success of fibrinolytic therapy was defined as complete restoration of valve function in the presence or absence of complications.

RESULTS

Eighteen patients (90%) had mitral PVT and two (10%) had aortic PVT. Thrombolytic therapy with streptokinase was successful in all but one case, with a total mortality of four cases (20%). In PVT episodes, before streptokinase therapy, the prosthetic valve areas (in all cases, mitral and aortic positions) were 0.82 ± 0.21, 0.83 ± 0.21, and 0.73 ± 0.18 cm²; and the peak and mean transvalvular gradients were 38.7 ± 16.7 and 25.4 ± 8.7, 34.1 ± 8.8 and 23.2 ± 5.4, and 80.0 ± 14.1 and 45.0 ± 7.1 mmHg, respectively. After streptokinase therapy, the prosthetic valve area and peak and mean transvalvular gradients improved significantly (for all cases, mitral and aortic positions: valve area 2.17 ± 0.58, 2.21 ± 0.61, and 1.85 ± 0.07 cm², peak gradient 18.7 ± 11.0, 16.4 ± 7.7, and 39.0 ± 18.4, and mean gradient 9.6 ± 7.1, 8.2 ± 5.3, and 22.0 ± 11.3 mmHg, respectively; paired t-test, P<0.001 for pre- versus post-streptokinase infusion for all variables).

CONCLUSION

Fibrinolytic therapy using streptokinase was an effective therapeutic strategy for the management of PVT and is a reasonable alternative to surgery.

Challenges in the echocardiographic assessment of aortic stenosis

Calcific aortic valve stenosis is common in the elderly. While history and examination can establish the diagnosis, determination of its severity typically requires echocardiography to define valve anatomy, measure stenosis severity and assess left ventricular response. The purpose of this review is to describe some of the commonly encountered challenges in the echocardiographic assessment of aortic stenosis. These include errors in the calculation of aortic valve area, assessment of aortic stenosis during atrial fibrillation, determining the presence of aortic stenosis in the setting of low transvalvular pressure gradients and discriminating other forms of obstruction to left ventricular ejection from aortic stenosis. Lastly, a review of how echocardiography is utilized to select patients for transcatheter aortic valve replacement is presented.

Patient-prosthesis mismatch increases the mean platelet volume in patients with aortic valve replacement

PURPOSE

Patient-prosthesis mismatch (PPM) is defined when the ratio of the effective orifice area of the normally functioning prosthetic valve to the body surface area of the patient is <0.85 cm(2)/m(2). The aim of this study was to assess the measurements of the mean platelet volume (MPV) as an indicator of platelet activation in patients with PPM.

METHODS

A total of 109 patients with isolated aortic valve replacement (AVR) procedures with a mechanical prosthesis and a control group from a normal population of 102 people compatible in terms of age and sex were chosen for the study. The AVR group was subdivided into a PPM group (n = 41) and non-PPM group (n = 68). All patients and control participants underwent echocardiographic examinations, with simultaneous measurements of the serum MPV values.

RESULTS

The MPV measurements were significantly higher in the patients with AVR compared to the control group (8.97 ± 0.93 vs. 8.26 ± 0.14, p < 0.001). Higher results were also obtained in the patients with PPM compared to the non-PPM group (9.36 ± 0.61 vs. 8.73 ± 1.01, p < 0.001). The platelet counts were found to be similar in both groups (p > 0.05).

CONCLUSIONS

We have herein shown that the PPM patients had a significantly higher MPV compared to the patients with AVR without PPM and healthy subjects.

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.

Flow acceleration time and ratio of acceleration time to ejection time for prosthetic aortic valve function

OBJECTIVES

We sought to evaluate whether ejection dynamics, particularly acceleration time (AT) and the ratio of AT to ejection time (ET), can differentiate prosthetic aortic valve (PAV) stenosis from controls and prosthesis-patient mismatch (PPM).

BACKGROUND

Diagnosing PAV stenosis, especially in mechanical valves, may be challenging and has significant clinical implications.

METHODS

Doppler echocardiography was quantitated in 88 patients with PAV (44 mechanical and 44 bioprosthetic; age 63 ± 16 years; valve size range 18 to 25 mm) of whom 22 patients had documented PAV stenosis, 22 had PPM, and 44 served as controls. Quantitative Doppler parameters included ejection dynamics (AT, ET, and AT/ET) and conventional PAV parameters.

RESULTS

Patients with PAV stenosis had significantly lower effective orifice area (EOA) values and higher gradients compared with controls and PPM. Flow ejection parameters (AT and AT/ET) were significantly longer in the stenotic valves compared with PPM and controls (respective values for AT: 120 ± 24 ms, 89 ± 16 ms, and 71 ± 15 ms; for AT/ET: 0.4, 0.32, and 0.3, p ≤ 0.001). Patients with PPM had gradients and ejection dynamics that were intermediate between normal and stenotic valves. Receiver-operator characteristic (ROC) curve analysis showed that AT and AT/ET discriminated PAV stenosis from PPM and controls (area under ROC curve = 0.92 and 0.88, respectively). Combining AT with the conventional Doppler velocity index gave the highest area under the curve of 0.98 but was not statistically different from that of AT alone (p = 0.12). A cutoff of AT = 100 ms had a sensitivity and specificity of 86% for identifying PAV stenosis; for an AT/ET = 0.37, the sensitivity and specificity were 96% and 82%, respectively. Analysis by valve type (mechanical and biological) revealed similar results; however, biological valves had slightly higher areas under the curve for all systolic time intervals.

CONCLUSIONS

Ejection dynamics through PAV, particularly AT and AT/ET, are reliable angle-independent parameters that can help evaluate valve function and identify PAV stenosis.

Patient-prosthesis mismatch in the mitral position affects midterm survival and functional status

BACKGROUND

The definition and incidence of patient-prosthesis mismatch (PPM) in the mitral position are unclear.

OBJECTIVES

To determine the impact of PPM on late survival and functional status after mitral valve replacement with a mechanical valve.

METHODS

Between 1992 and 2005, 714 patients (mean [± SD] age 60±10 years) underwent valve replacement with either St Jude (St Jude Medical Inc, USA) (n=295) or Carbomedics (Sulzer Carbomedics Inc, USA) (n=419) valves. There were 52 concomitant procedures (50 tricuspid annuloplasties, 25 foramen oval closures and 20 radiofrequency mazes). The mean clinical follow-up period was 4.4±3.3 years. The severity of PPM was established with cut-off values for an indexed effective orifice area (EOAi) of lower than 1.2 cm(2)⁄m(2), lower than 1.3 cm(2)⁄m(2) and lower than 1.4 cm(2)⁄m(2). Parametric and nonparametric tests were used to determine predictors of outcome.

RESULTS

The prevalence of PPM was 3.7%, 10.1% and 23.5% when considering values of lower than 1.2 cm(2)⁄m(2), lower than 1.3 cm(2)⁄m(2) and lower than 1.4 cm(2)⁄m(2), respectively. When considering functional improvement, patients with an EOAi of 1.4 cm(2)⁄m(2) or greater had a better outcome than those with an EOAi of lower than 1.4 cm(2)⁄m(2) (OR 1.98; P=0.03). When building a Cox-proportional hazard model, PPM with an EOAi of less than 1.3 cm(2)⁄m(2) was an independent predictive factor for midterm survival (HR 2.24, P=0.007). Other factors affecting survival were age (HR 1.039), preoperative New York Heart Association class (HR 1.96) and body surface area (HR 0.31).

CONCLUSIONS

In a large cohort of patients undergoing mitral valve replacement with mechanical prostheses, PPM defined as an EOAi of lower than 1.3 cm(2)⁄m(2) significantly decreased midterm survival. This level of PPM was observed in 10.2% of patients. Patients with an EOAi of 1.4 cm(2)⁄m(2) or greater had greater improvement of their functional status.

Diagnostic evaluation of left-sided prosthetic heart valve dysfunction

Prosthetic heart valve (PHV) dysfunction is a rare, but potentially life-threatening, complication. In clinical practice, PHV dysfunction poses a diagnostic dilemma. Echocardiography and fluoroscopy are the imaging techniques of choice and are routinely used in daily practice. However, these techniques sometimes fail to determine the specific cause of PHV dysfunction, which is crucial to the selection of the appropriate treatment strategy. Multidetector-row CT (MDCT) can be of additional value in diagnosing the specific cause of PHV dysfunction and provides valuable complimentary information for surgical planning in case of reoperation. Cardiac magnetic resonance imaging (CMR) has limited value in the evaluation of biological PHV dysfunction. In this Review, we discuss the use of established imaging modalities for the detection of left-sided mechanical and biological PHV dysfunction and discuss the complementary role of MDCT in this context.

Impact of hypertension on left ventricular structure in patients with asymptomatic aortic valve stenosis (a SEAS substudy)

OBJECTIVE

Both hypertension and aortic valve stenosis induce left ventricular hypertrophy. However, less is known about the influence of concomitant hypertension on left ventricular structure in patients with aortic valve stenosis.

METHODS

Baseline Doppler echocardiography was performed in 1720 patients with asymptomatic aortic valve stenosis (peak transaortic velocity >or=2.5 m/s and <or=4.0 m/s) recruited in the Simvastatin and Ezetimibe in Aortic Stenosis study at 173 centers in seven European countries. Patients were grouped as normotensive (n = 482) or hypertensive (n = 1238) according to history of hypertension or clinic blood pressure greater than 140 mmHg systolic or greater than 90 mmHg diastolic at baseline visits.

RESULTS

Hypertensive patients were older, more obese, and included more women (all P < 0.05). Furthermore, the hypertensive group had higher wall thicknesses and left ventricular mass and higher prevalence of left ventricular hypertrophy (40 vs. 25%) and increased relative wall thickness (21 vs. 14%, both P < 0.01). On the basis of aortic valve area and energy loss the degree of aortic valve stenosis did not differ between the groups. In multivariate analysis, hypertension predicted higher left ventricular mass independent of other well known confounders including male sex, circumferential end-systolic stress, body mass index, aortic regurgitation, left ventricular ejection fraction and severity of aortic stenosis (multiple R = 0.30, P < 0.001).

CONCLUSION

In patients with asymptomatic aortic stenosis, concomitant hypertension significantly influences left ventricular geometry and is associated with higher left ventricular mass, relative wall thickness and higher prevalence of left ventricular hypertrophy.

Early Doppler-echocardiography evaluation of 597 prosthetic aortic valves

OBJECTIVES

This study was designed to describe the Doppler-echocardiography normal values in the early postoperative phase for Carpentier-Edwards Perimount Aortic Heart Valve bioprosthesis (CEP), St. Jude Medical (SJM) or Medical Regent (SJMR) Mechanical Heart Valves, evaluated by a single experienced echo-laboratory.

METHODS

Five hundred and ninety-seven consecutive patients in our hospital, who had had a CEP, a SJM or SJMR-17 mm implanted due to aortic stenosis, underwent a control Doppler-echocardiography evaluation 4-7 days after surgery. Hemodynamic performance of SJM, SJMR and CEP were accurately described, evaluating flow-dependent (trans-prosthetic velocities and gradients) and flow-independent (effective orifice area, indexed effective orifice area and Doppler velocity index) Doppler-echocardiography parameters.

RESULTS

Of the 597 patients 50.6% were women (n = 302). Mean age was 66.3 +/- 11.7 years. Mean body surface area (BSA) was 1.76 +/- 0.22 m. Mean ejection fraction was 55.3 +/- 10.3%. Two hundred and sixty CEPs and 337 St. Jude mechanical valves (301 SJM and 36 SJMR size-17) were implanted. Comparing size-by-size SJM to CEP, the former were basically less flow obstructive.

CONCLUSION

Our data confirm the wide range of variability, pointing out the need to perform routinely an accurate baseline Doppler-echocardiography evaluation of the hemodynamic profile of prosthetic aortic valves, including flow-dependent and independent parameters, to allow an adequate interpretation at follow-up.

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.

Flow through a defective mechanical heart valve: a steady flow analysis

Approximately 250,000 valve replacement operations occur annually around the world and more than two thirds of these operations use mechanical heart valves (MHV). These valves are subject to complications such: pannus and/or thrombus formation. Another potential complication is a malfunction in one of the valve leaflets. Although the occurrence of such malfunctions is low, they are life-threatening events that require emergency surgery. It is, therefore, important to develop parameters that will allow an early non-invasive diagnosis of such valve malfunction. In the present study, we performed numerical simulations of the flow through a defective mechanical valve under several flow and malfunction severity conditions. Our results show that the flow upstream and downstream of the defective valve is highly influenced by malfunction severity and this resulted in a misleading improvement in the correlation between simulated Doppler echocardiographic and catheter transvalvular pressure gradients. In this study, we were also able to propose and test two potential non-invasive parameters, using Doppler echocardiography and phase contrast magnetic resonance imaging, for an early detection of mechanical heart valve malfunction. Finally, we showed that valve malfunction has a significant impact on platelet activation and therefore on thrombus formation.

Impact of valve prosthesis-patient mismatch estimated by echocardiographic-determined effective orifice area on long-term outcome after aortic valve replacement

BACKGROUND

The impact of valve prosthesis-patient mismatch on long-term outcome after aortic valve replacement estimated by various variables such as projected indexed effective orifice area and internal geometric orifice area obtained from in vivo or in vitro published data is still controversial.

METHODS

The effective orifice area was measured by echocardiography in 533 patients. The mean age of the patients was 71 +/- 9 years; mean follow-up time was 4.7 +/- 2.2 years. The impact of severe (indexed effective orifice area <or=0.6 cm(2)/m(2)) and moderate mismatch (0.6 cm(2)/m(2) < indexed effective orifice area <or=0.85 cm(2)/m(2)) on survival was evaluated by Cox regression.

RESULTS

Severe mismatch (hazard ratio: 1.9 [1.08-3.21]) was a significant predictor of survival time after adjustment for age, left ventricular ejection fraction, atrial fibrillation, New York Heart Association class, serum creatinine, and hemoglobin level. The 5- and 7-year survival rates were 71% +/- 4% and 54% +/- 8% for patients with severe mismatch and 83% +/- 4% and 80% +/- 8% for patients with mild mismatch, respectively. The correlation between projected and measured indexed effective orifice area was of medium strength (r = 0.49), and the frequency of observed mismatch depended linearly on the projected indexed effective orifice area. Although projected indexed effective orifice area and indexed internal geometric orifice area were significant predictors of severe mismatch, the sensitivity and specificity for severe prosthesis-patient mismatch were only 75% and 52%, using an optimal threshold of projected indexed effective orifice area defined by the Youden index.

CONCLUSIONS

Severe prosthesis-patient mismatch estimated by effective orifice area measured within 10 days was an independent risk factor of survival time. Projected indexed effective orifice area determined at surgery does not sufficiently predict mismatch.

Long-term results of aortic valve replacement with a small St. Jude medical valve in Japanese patients

BACKGROUND

The use of small aortic valve prostheses is still controversial because of negative effects caused by residual obstruction of the left ventricular outflow tract. This study evaluated the long-term results after aortic valve replacement with a small valve from St. Jude Medical (St. Paul, MN).

METHODS

Between 1980 and 1999, 221 patients underwent isolated aortic valve replacement with a 23-mm or smaller St. Jude Medical valve. The mortality rate and complications were analyzed, echocardiography was performed, and peak pressure gradient, mean pressure gradient, indexed effective orifice area, and left ventricular mass index were measured.

RESULTS

The follow-up rate in the 221 patients was 99.5% (maximum length, 24.1 years; mean, 10.3 years). Patients with a 19-mm valve were mainly women, older, and had smaller body surface areas. Freedom from valve-related death at 20 years was 100%, 86.0%, and 90.2% in patients with 19-, 21-, and 23-mm valves, respectively. There were no significant differences in the actuarial freedom from valve-related deaths. Echocardiography showed significantly higher peak (32.3 mm Hg) and mean pressure gradients (17.6 mm Hg) and a smaller indexed effective orifice area (0.70 +/- 0.15 cm(2)/m(2)) in patients with a 19-mm valve than in those with a 21- or 23-mm valve. Moderate prosthesis-patient mismatch was present in most patients with a 19-mm valve according to one definition; however, the improvements in ejection fraction and left ventricular mass index were significant, and functional recovery (mean New York Heart Association class, 1.3 +/- 0.5; mean specific activity scale, 5.1 +/- 0.8 metabolic equivalents) was satisfactory.

CONCLUSIONS

The present long-term results demonstrate that a small St. Jude Medical valve can be advantageously used in most Japanese patients because their body size is generally smaller than that of Western patients. These findings also emphasize that it is not prosthesis size per se that matters but rather the relation between body size and prosthesis size.

Factors influencing left ventricular structure and stress-corrected systolic function in men and women with asymptomatic aortic valve stenosis (a SEAS Substudy)

To identify determinants of left ventricular (LV) structure and stress-corrected systolic function in men and women with asymptomatic aortic stenosis (AS), Doppler echocardiography was performed at baseline in 1,046 men and 674 women 28 to 86 years of age (mean 67 +/- 10) recruited in the Simvastatin Ezetimibe in Aortic Stenosis (SEAS) study evaluating placebo-controlled combined simvastatin and ezetimibe treatment in AS. LV hypertrophy was less prevalent in women despite older age, higher systolic blood pressure, and smaller aortic valve area/body surface area (all p values <0.05). In logistic regression analyses, LV hypertrophy was independently associated with male gender, severity of AS, hypertension, higher systolic blood pressure, and lower stress-corrected midwall shortening (scMWS) or stress-corrected fractional shortening (scFS; all p values <0.01). In men aortic regurgitation also was a predictor of LV hypertrophy (p <0.05). Women had greater scFS and scMWS when corrected for LV size or geometry (all p values <0.001). In multivariate analyses, female gender predicted 11% greater scFS and 4% greater scMWS independent of age, body mass index, heart rate, aortic valve area, LV mass, relative wall thickness, aortic regurgitation, hypertension, and end-systolic stress (R(2) = 0.23 and 0.59, respectively, p <0.001). In conclusion, the major determinants of LV hypertrophy in patients with asymptomatic AS are male gender, severity of AS, and concomitant hypertension. Women have higher stress-corrected indexes of systolic function independent of LV geometry or size, wall stress, older age, or more concomitant hypertension.

Prosthetic heart valves: Types and echocardiographic evaluation

In the last five decades multiple different models of prosthetic valves have been developed. The purpose of this article is to provide a comprehensive source of information for the types and the echocardiographic evaluation of the prosthetic heart valves.

Prosthesis-Patient Mismatch is Associated with Higher Operative Mortality Following Aortic Valve Replacement

BACKGROUND

Prosthesis-patient mismatch (PPM) occurs when the valve prosthesis implanted at surgery is too small in relation to patient's body size, causing high transvalvular gradients. We investigated if severe PPM is related to early morbidity and mortality after aortic valve replacement (AVR).

METHODS

We analysed prospectively collected data of 701 consecutive patients undergoing AVR between June 2001 and February 2006 at two Australian public hospitals. The indexed valve effective orifice area (IEOA) was estimated for each valve prosthesis implanted. PPM was defined as <or=0.65 cm2 m(-2). PPM was correlated with operative mortality, stroke, prolonged ventilation, new renal failure, prolonged intensive care stay, prolonged hospital stay and readmission to hospital within 30 days by univariate and multivariate methods.

RESULTS

PPM was present in 6.6% of patients. Overall operative mortality was 4.1%. Isolated AVR was performed in only 38.4% of patients. For patients with PPM, the univariate and multivariate odds ratio for mortality were 5.2 (P=0.002) and 6.1 (P=0.006), respectively. The other multivariate predictors of mortality were age, pre-operative serum creatinine, emergency status, pulmonary artery pressure and bypass time. PPM was not associated with stroke, prolonged ventilation, new renal failure, prolonged intensive care or hospital stay, or readmission within 30 days.

CONCLUSION

PPM was associated with increased operative mortality. PPM should be avoided where possible as it may reduce operative mortality following AVR.

Clinical and echocardiographic assessment of the Medtronic Advantage aortic valve prosthesis: the Scandinavian multicentre, prospective study

OBJECTIVE

The aim of this report is the prospective, multicentre evaluation of clinical results and haemodynamic performance of the Medtronic Advantage aortic valve prosthesis.

METHODS

From April 2001 to June 2003, 166 patients (male:female 125:41; mean (SD) age 61.8 (11.8) years) received an aortic advantage valve prosthesis. Complete cumulative follow-up was 242.7 patient-years (maximum 3.2; mean 1.6 years). Postoperatively, patients underwent early (within 30 days) and 1 year transthoracic echocardiography.

RESULTS

30 day mortality was 2.4% (n = 4). Kaplan-Meier estimates of freedom from complications and linearised rates were as follows: 96.9 (1.6)% survival; 94.7 (1.3)% (2.06 patients/year) thrombo-embolism; 99.4 (0.6)% (0.4 patients/year) bleeding; 98.8 (0.9)% (0.8 patients/year) non-structural valve dysfunction; 98.8 (0.9)% (0.8 patients/year) reoperation. Valvular mean pressure gradients ranged from 16 (3) mm Hg for size 19 to 7 (2) mm Hg for size 27 and the corresponding effective orifice areas ranged from 1.2 (0.25) to 3.2 (0.66) cm(2). In all, left ventricular mass significantly decreased (p<0.001) and fractional shortening increased (p<0.001) from postoperative to 1 year echocardiography.

CONCLUSIONS

Haemodynamic performance and early clinical results of Medtronic advantage in the aortic position were satisfactory and comparable with those of other bileaflet valves in current clinical use.

Association between indices of prosthesis internal orifice size and operative mortality after isolated aortic valve replacement

OBJECTIVES

The appropriate index of prosthesis internal orifice size and its effect on operative mortality after aortic valve replacement are controversial. We examined the association between several relevant indices and patient size on operative mortality. Indices examined included projected in vivo effective orifice area and geometric orifice area, with patient size defined as body surface area.

METHODS

A review of the Society of Thoracic Surgeons National Cardiac Database (2000-2004) yielded 48,722 patients who had isolated aortic valve replacement. This analysis is based on the cohort of 42,310 patients with the 8 most prevalent valve types with manufacturer's labeled sizes 19 mm through 29 mm. Multivariable logistic regression models were employed to determine the effects of body surface area, effective orifice area, geometric orifice area, and selected derived indices (eg, effective orifice area/body surface area) on risk-adjusted operative mortality.

RESULTS

In separate multivariable models, effective orifice area and geometric orifice area were both inversely correlated with operative mortality. However, an unanticipated finding was that with either effective orifice area or geometric orifice area held constant, body surface area was significantly and inversely correlated with operative mortality. When patients were stratified by effective orifice area, geometric orifice area, or manufacturer's labeled valve size and type, elevations in body surface area were associated with a decrease rather than an increase in operative mortality.

CONCLUSIONS

Prostheses with small geometric orifice area or small effective orifice area are associated with increased operative mortality after isolated aortic valve replacement. Even for valves with small effective orifice area, however, mortality decreases as body surface area increases. With respect to operative mortality, therefore, our results do not support using arbitrary cutoff values of effective orifice area/body surface area to determine the valve to utilize in a given patient.

New insights into the assessment of the prosthetic valve performance in the presence of subaortic stenosis through a fluid-structure interaction model

The aim of this study was to contribute to improving the accuracy of clinical assessments of valve performance in situations involving the concomitant presence of a prosthetic valve and subaortic stenosis (SAS). Physiological flow in a two-dimensional model for a bileaflet mechanical heart valve was investigated numerically in terms of the fluid-structure interactions. The fluid dynamics in a model with SAS of the left ventricle outflow tract were compared with those given by a healthy model. The results show that in the model with SAS, one leaflet did not close during the observed systolic phase, whereas the other one showed similar behaviour to that of the leaflet in the healthy model. In addition, the main flow did not occur along the central axis and a deviated jet was set up between leaflets, contrary to what occurred in the model without SAS. Current clinical diagnostic indices, which are mainly based on the central jet flow velocities, are therefore unsuitable for use in this pathological situation and should be used with great caution.

Clinical and hemodynamic implications of supra-annular implant of biological aortic valves

The use of stented bioprostheses in elderly patients with degenerative aortic stenosis, despite being desirable, raises concerns about the harmful effects of residual obstruction to left ventricular outflow. To overcome this limitation new stented and stentless bioprostheses have been designed for supra-annular implant. However, the actual hemodynamic advantage of supra-annular implant over the intra-annular one remains incompletely understood. This review focuses on the geometry of biological valve prostheses designed for supra-annular implant and its implications for the echocardiographic assessment of valve hemodynamics. Available data about the hemodynamic performance of these valves implanted in the supra-annular position in comparison with the usual intra-annular implant are also reviewed. Other issues related to biological heart valve performance, such as biomaterials, tissue mechanics, durability, and clinical outcome are not addressed in this review.

Risk Factors for Postoperative Heart Failure in Patients Operated on for Aortic Stenosis

BACKGROUND

Risk factors for postoperative heart failure (PHF) have not been specifically studied in valve surgery although it has been acknowledged that patient variables may have a more profound influence on postoperative outcome than valve-related factors.

METHODS

All patients undergoing isolated aortic valve replacement for aortic stenosis from January 1995 to December 2000 in the southeast region of Sweden were studied (n = 398). Forty-five patients with aortic valve replacement required treatment for PHF. Univariate and multivariate logistic regression analysis was carried out to identify risk factors for PHF.

RESULTS

Thirty-day mortality was 6.7% versus 1.4% for patients with and without PHF, respectively (p = 0.05). With regard to clinical presentation of aortic stenosis, angina was associated with reduced risk, whereas history of congestive heart failure increased the risk for PHF. Five preoperative (hypertension, history of congestive heart failure, severe systolic left ventricular dysfunction, pulmonary hypertension, preoperative hemodynamic instability) and two intraoperative (aortic cross-clamp time, intraoperative myocardial infarction) variables were identified as independent risk factors for PHF. Patient-prosthesis mismatch did not influence the risk of PHF significantly.

CONCLUSIONS

Postoperative heart failure was associated with a marked increase in postoperative mortality and morbidity. Risk factors for PHF were variables indicating preexisting myocardial dysfunction, increased right or left ventricular afterload, and intraoperative myocardial injury. Our results highlight issues concerning cross-clamp time and myocardial protection, particularly for patients with preoperatively compromised myocardial function. Asymptomatic patients with significant aortic stenosis should be considered for surgery before substantial echocardiographic evidence of left ventricular dysfunction or increased pulmonary artery pressure develops.

Use of the Ejection Fraction-Velocity Ratio in the Hemodynamic Assessment of Aortic Bioprosthetic Valves

BACKGROUND

A new echocardiographic severity index of aortic valve stenosis has been recently introduced: the ejection fraction-velocity ratio (EFVR), which is a simple ratio ejection fraction/4Vmax2. This nonflow corrected index demonstrated an excellent accuracy in quantifying the effective orifice area (EOA) in native aortic valves. There is no information about the reliability of EFVR in assessing aortic EOA in patients with bioprostheses.

METHODS

In 141 consecutive patients with aortic bioprostheses (85 males, mean age 74 +/- 9 years), EOA was calculated by both continuity equation (CE) and EFVR.

RESULTS

The correlation between CE and EFVR was highly significant (r = 0.88; P < 0.0001). The area under the receiver operating characteristic (ROC) curve was 0.97 (considering a positive case CE < 1.0 cm2, best cutoff of EFVR was <1.06). Using CE as gold standard and a cutoff of 1.0 for both indexes, EFVR showed good sensitivity (80%) and specificity (98%). Also in a subgroup of 46 patients with moderate or severe mitral regurgitation, the EFVR had a good diagnostic accuracy (sensitivity 89%, specificity 97%). In 91 patients with ejection fraction < or = 50%, the EFVR confirmed good sensitivity (79%) and specificity (97%).

CONCLUSIONS

The EFVR, a simple and not time-consuming index, demonstrated a good diagnostic accuracy in assessing EOA also in patients with aortic bioprostheses. The presence of moderate to severe mitral regurgitation or left ventricular dysfunction does not reduce significantly the reliability of this new index. The EFVR can be taken into consideration in the clinical practice, at least when CE measurements are technically difficult.

Prosthesis-Patient Mismatch After Aortic Valve Replacement: Impact of Age and Body Size on Late Survival

BACKGROUND

The purpose of this study was to identify patient subgroups in which prosthesis-patient mismatch most influenced late survival.

METHODS

Over a 12-year period, 1,400 consecutive patients underwent bioprosthetic (933 patients) or mechanical (467) aortic valve replacement. Prosthesis-patient mismatch was defined as prosthetic effective orifice area/body surface area less than 0.75 cm2/m2 and was present with 11% mechanical and 51% bioprosthetic valves.

RESULTS

With bioprosthetic valves, prosthesis-patient mismatch was associated with impaired survival for patients less than 60 years old (10-year: 68% +/- 7% mismatch versus 75% +/- 7% no mismatch, p < 0.02) but not older patients (p = 0.47). Similarly, with mechanical valves, prosthesis-patient mismatch was associated with impaired survival for patients less than 60 years old (10-year: 62% +/- 11% versus 79% +/- 4%, p < 0.005) but not older patients (p = 0.26). For small patients (body surface area less than 1.7 m2), prosthesis-patient mismatch did not impact survival with bioprosthetic (p = 0.32) or mechanical (p = 0.71) valves. For average-size patients (body surface area 1.7 to 2.1 m2), prosthesis-patient mismatch was associated with impaired survival with both bioprosthetic (p < 0.05) and mechanical (p < 0.005) valves. For large patients (body surface area greater than 2.1 m2), prosthesis-patient mismatch was associated with impaired survival with mechanical (p < 0.04) but not bioprosthetic (p = 0.40) valves.

CONCLUSIONS

Prosthesis-patient mismatch had a negative impact on survival for young patients, but its impact on older patients was minimal. In addition, although prosthesis-patient mismatch was not important in small patients, prosthesis-patient mismatch negatively impacted survival for average-size patients and for large patients with mechanical valves.

Is the Valve OK or Not? Immediate Evaluation of a Replaced Aortic Valve

Transesophageal echocardiography is a crucial tool in intraoperative evaluation of newly implanted/repaired heart valves because suspected valvular malfunction needs to be identified and sometimes surgically corrected. Although color Doppler is often adequate in evaluating the expected regurgitant jets, as well as excluding pathologic paravalvular leaks, spectral Doppler techniques are the most commonly used methods for estimating transvalvular gradients in the operating room. However, these methods are subject to a variety of confounding factors, including subvalvular gradients and pressure recovery. Other methods of valve area estimation should also be used when evaluating a prostethic aortic valve, including the continuity equation and the left ventricular outflow tract/aortic valve velocity ratio.

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.

Small “Functional” Size after Mechanical Aortic Valve Replacement: No Risk in Young to Middle-Age Patients

BACKGROUND

The impact of a valve prosthesis-patient size mismatch is still controversial. In most studies, the inclusion of a large proportion of poorly active old patients with low cardiac output requirements may be misleading, due to the close correlation between trans-prosthetic gradients and cardiac output. The aim of this study was to assess the impact of small "functional" prosthesis sizes in active young to middle-age patients.

METHODS

Eighty-three active patients with a mean age of 46 +/- 8 years and a high health survey questionnaire score were followed for 80 +/- 34 months after isolated aortic valve replacement with a mechanical prosthesis.

RESULTS

Patients with an indexed, Doppler derived, effective orifice area index less than 0.85 cm2/m2 (0.77 +/- 0.1 cm2/m2) showed higher early trans-prosthetic gradients (peak, 34 +/- 11 vs 26 +/- 8 mm Hg; P = 0.001) than patients with a larger effective orifice area index. However, significant regression of the left ventricular mass index and improvement of the left ventricular ejection fraction were observed in both groups at follow-up (119.8 +/- 26 vs 165.2 +/- 38 g/m2 and 128.5 +/- 25 vs 181.8 +/- 50 g/m2; P < 0.001; 58 +/- 6 vs 52 +/- 11% and 58 +/- 7 vs 53 +/- 10%; P < 0.001), with no differences between groups (P = 0.4 and P = 0.7, respectively). At multiple linear regression, the final left ventricular mass index was positively related to the preoperative left ventricular mass index (P = 0.004) and was unaffected by the effective orifice area index (P = 0.4). Symptomatic improvement (New York Heart Association class 1.3 +/- 0.4 vs 2.4 +/- 0.8 and 1.2 +/- 0.4 vs 2.2 +/- 0.8; P < 0.001) and freedom from late cardiac death (93 +/- 3% and 95 +/- 6%) were comparable between groups (P = 0.6 and P = 0.7, respectively).

CONCLUSIONS

Our findings indicate that small "functional" prosthesis sizes with modern mechanical valves may not adversely affect outcomes of aortic valve replacement in young patients with high cardiac output requirements.