In-vivo prediction of cavitation near a Medtronic Hall valve

BACKGROUND AND AIM OF THE STUDY: Quantification of cavitation near mechanical heart valves in vivo is currently based on measurements of high-frequency pressure fluctuations (HFPF). Until now, mechanical resonance components have been removed using a high-pass filter. However, isolating cavitation and resonance signal components by separating the deterministic and non-deterministic parts of the HFPF signal has recently been proposed as a new method. It was hypothesized that the non-deterministic signal energy, Enon-det, of the HFPF signal correlates with previous parameters indicating cavitation in vivo, specifically the root mean square pressure after appropriate high-pass filtering (P(RMS)) and the rate of change in transvalvular pressure with respect to time (dP/dt). METHODS: Medtronic Hall 29 mm mitral valves were implanted in five pigs (body weight 80 kg). The hemodynamic condition was varied by infusion of dobutamine and blood volume regulation to achieve a wide range of dP/dt (100 to 4,700 mmHg/s). According to previous studies, P(RMS) was deduced using the HP-filtering cut-off frequency of 50 kHz for this particular valve. The transvalvular dP/dt was derived as the average slope 5 ms prior to valve closure. RESULTS: Power relationships were found between Enon-det and P(RMS) (P(RMS) = 1.27 x Enon-det0.49), and between Enon-det and dP/dt. The correlation between Enon-det and P(RMS) was very strong (r = 0.98), whereas the correlation between Enon-det and dP/dt was notably weaker (r = 0.68). CONCLUSION: Enon-det was an excellent predictor of P(RMS), obtained after appropriate filtering. The present data suggested that the signal energy above 50 kHz was almost completely non-deterministic. It can therefore be proposed that Enon-det is a more direct and easily accessible parameter than those previously suggested for the purpose of cavitation quantification. This parameter is able to quantify the pressure fluctuations thought to occur from cavitation in vivo, and may be applicable for non-invasive recordings.     

Transcatheter Aortic Valve-in-Valve Implantation for Patients With Degenerative Surgical Bioprosthetic Valves

Most surgical heart valves currently implanted are bioprosthetic tissue valves. Such valves deteriorate with time, eventually presenting with either stenosis or regurgitation. Reoperation, the current standard of care for failed valves, carries significant risk in terms of both morbidity and mortality. Implantation of a transcatheter valve inside a failed surgical valve (valve-in-valve procedure) has recently emerged as an alternative, less-invasive option. Although the procedure is similar in some aspects to transcatheter aortic valve implantation in the setting of native aortic valve stenosis, there are many differences that deserve special consideration. We review the potential and challenges of valve-in-valve implantation in patients with failing surgical aortic bioprostheses.     

18F-GP1 Positron Emission Tomography and Bioprosthetic Aortic Valve Thrombus

BackgroundBioprosthetic valve thrombosis may have implications for valve function and durability.ObjectivesUsing a novel glycoprotein IIb/IIIa receptor radiotracer 18F-GP1, we investigated whether positron emission tomography (PET)-computed tomography (CT) could detect thrombus formation on bioprosthetic aortic valves.MethodsEx vivo experiments were performed on human platelets and explanted bioprosthetic aortic valves. In a prospective cross-sectional study, patients with either bioprosthetic or normal native aortic valves underwent echocardiography, CT angiography, and 18F-GP1 PET-CT.ResultsFlow cytometric analysis, histology, immunohistochemistry, and autoradiography demonstrated selective binding of 18F-GP1 to activated platelet glycoprotein IIb/IIIa receptors and thrombus adherent to prosthetic valves. In total, 75 participants were recruited: 53 with bioprosthetic valves (median time from implantation 37 months [IQR: 12-80 months]) and 22 with normal native aortic valves. Three participants had obstructive valve thrombosis, and a further 3 participants had asymptomatic hypoattenuated leaflet thickening on CT angiography. All bioprosthetic valves, but none of the native aortic valves, demonstrated focal 18F-GP1 uptake on the valve leaflets: median maximum target-to-background ratio 2.81 (IQR: 2.29-3.48) vs 1.43 (IQR: 1.28-1.53) (P < 0.001). Higher 18F-GP1 uptake was independently associated with duration of valve implantation and hypoattenuated leaflet thickening. All 3 participants with obstructive valve thrombosis were anticoagulated for 3 months, leading to resolution of their symptoms, improvement in mean valve gradients, and a reduction in 18F-GP1 uptake.ConclusionsAdherence of activated platelets is a common and sustained finding on bioprosthetic aortic valves. 18F-GP1 uptake is higher in the presence of thrombus, regresses with anticoagulation, and has potential use as an adjunctive clinical tool. (18F-GP1 PET-CT to Detect Bioprosthetic Aortic Valve Thrombosis; NCT04073875)     

A guide to fluoroscopic identification and design of bioprosthetic valves: A reference for valve‐in‐valve procedure

Surgical aortic valve replacement remains the therapy of choice in majority of patients with aortic stenosis. Bioprosthetic heart valves are often preferred over mechanical valves as they preclude the need for anticoagulation with its associated risks of bleeding and thromboembolism. However, bioprosthetic heart valves undergo structural deterioration and eventually fail. Reoperation is the standard treatment for structural failure of the bioprosthetic valve, stenosis or regurgitation but can carry a significant risk, especially in elderly patients with multiple comorbidities. Transcatheter aortic valve implantation has recently been established as a feasible alternative to conventional valve surgery for the management of high‐risk elderly patients with aortic stenosis. This treatment modality has also been shown to be of benefit in the management of degenerated aortic bioprosthesis as a valve‐in‐valve procedure. The success of this procedure depends on a good understanding of the failing bioprostheses. This not only includes the device design but its radiological/fluoroscopic appearance and how it correlates with the implanted valve, as transcatheter aortic valve implantation is performed under fluoroscopic guidance. Here we illustrate the fluoroscopic appearance of 11 commercially available surgical bioprostheses and two commercially available transcatheter heart valves and discuss important aspects in their design which can influence outcome of a valve‐in‐valve procedure. We have also collated relevant information on the aspects of the design of a bioprosthetic valve, which are relevant to the valve‐in‐valve procedure. © 2012 Wiley Periodicals, Inc.     

Preferability of bioprostheses for isolated aortic valve replacement--a comparative study between mechanical and bioprosthetic valves

Comparative long-term performance characteristics of mechanical valves and bioprosthetic valves were analyzed retrospectively among patients who had undergone isolated aortic valve replacement between 1968 and 1987. One hundred sixty-seven patients received either mechanical (n = 82) or bioprosthetic (n = 85) valves. The cumulative follow-up was 926 patient-years (mean 6.1 +/- 4.7 years, ranging from 0.5 to 20.2 years, 100% complete follow-up). Actuarial survival rate, including operative death, at 10 years was 74 +/- 7% for mechanical and 77 +/- 7% for bioprosthetic valve recipients. The rates of freedom from thromboembolism, structural valve failure, prosthetic valve endocarditis, and valve re-replacement at 10 years were 77 +/- 7%, 100%, 96 +/- 2% and 95 +/- 3% for mechanical, and 94 +/- 4%, 83 +/- 8% (p less than 0.05), 88 +/- 5% and 75 +/- 8% (p less than 0.05) for bioprosthetic valve recipients, respectively. Thromboembolism occurred more frequently in the mechanical valve recipients (p less than 0.01), and structural valve failure in the bioprostheses recipients (p less than 0.05). There was no mortality at the time of valve re-replacement. Most of the bioprosthesis recipients received no anticoagulation therapy beyond 3 months postoperatively. Cardiac medication in the late postoperative period was not required in 31.3% of bioprosthetic, and 3.2% of mechanical valve recipients (p less than 0.01). These results show that bioprosthesis in the aortic position exhibits a superb antithrombogenicity and may enable a drug-free state, though its limited durability requires reoperation.     

Prosthetic heart valves

The first prosthetic valve was implanted by Hufnagel in 1952 in a patient with aortic insufficiency. Since then, prosthetic valves have evolved into various mechanical and bioprosthetic shapes and sizes. Despite the excitement surrounding the current development of prosthetic heart valves, surgically implanted valves remain the mainstay of current practice, and this article discusses the hemodynamic issues associated with the more commonly placed valves.     

Evaluation of stentless kangaroo aortic valves in the mitral position of juvenile sheep

BACKGROUND AND AIM OF THE STUDY: The performance and longevity of bioprosthetic heart valves are limited by tissue calcification and degeneration after implantation. Experimental valve replacement in large animal models forms an important component of the preclinical evaluation of these bioprosthetic heart valves. The study aim was to assess the feasibility of a mitral model for stentless valves and to evaluate the calcification behavior of stentless glutaraldehyde-preserved kangaroo heart valves in the mitral position of a sheep model. METHODS: Medtronic Freestyle (n = 10) and kangaroo (n = 11) stentless aortic valves were implanted in the mitral position of juvenile sheep and retrieved after a maximum of 200 days. Retrieved stentless valves were examined for morphological changes and calcification of the valve tissue, using radiological screening, Von Kossa's staining and atomic absorption spectrophotometry. RESULTS: Four sheep (40.0%) with Medtronic Freestyle and 10 sheep (90.9%) with kangaroo valves could be weaned from bypass and mechanical ventilation. Two animals (20.0%) with Medtronic Freestyle and six animals (54.5%) with kangaroo prostheses survived more than 30 days postoperatively. No significant difference (p >0.05) was seen between the calcification potential of Medtronic Freestyle valve leaflets (3.21 +/- 1.67 microg/mg) after 93 days and kangaroo valve leaflets (2.39 +/- 0.80 microg/mg) after 200 days. CONCLUSION: The present results suggest that implantation of a stentless valve in the mitral position of sheep is possible, but technically difficult. The calcification potential of kangaroo valve tissue is comparable to that of Freestyle valve tissue in the mitral position of sheep.     

Usefulness of phenprocoumon for the treatment of obstructing thrombus in bioprostheses in the aortic valve position

Bioprosthetic valve replacement is the treatment of choice in older patients with symptomatic severe aortic valve disease. Thrombosis of bioprosthetic valves has been considered a rare complication; however, in the presence of valvular obstruction, therapeutic consequences for the individual patient may be dramatic including repeat valve replacement or thrombolysis. We therefore evaluated oral anticoagulation with phenprocoumon as an alternative treatment for obstructive thrombosis of bioprosthetic valves. Six of 470 patients who had received a single stented bioprosthetic aortic valve from January 2007 through December 2008 at our hospital presented with obstructive bioprosthetic valve thrombosis within 14 months postoperatively. All 6 patients (1% of study population) had received a porcine valve (p = 0.1 vs pericardial), were hemodynamically stable, were in sinus rhythm, and were taking acetylsalicylic acid 100 mg/day. Echocardiography showed an increase in mean pressure gradient early postoperatively from 23.3 ± 4 to 57.0 ± 10 mm Hg (p <0.001). Five patients were started on phenprocoumon and followed for 114 ± 54 days, when mean pressure gradient had returned to 23.5 ± 6 mm Hg. No adverse events were observed during that period. One patient presenting with dyspnea and fever underwent emergency repeat valve replacement for suspected endocarditis, with histology showing long-term thrombosis of the explanted valve. In conclusion, oral anticoagulation with phenprocoumon represents a safe and effective treatment in clinically stable patients with obstructive thrombosis of bioprosthetic aortic valves, thus obviating repeat valve surgery or thrombolysis.     

Mid-term results of small-sized St. Jude Medical Regent prosthetic valves (21 mm or less) for small aortic annulus

Prosthesis–patient mismatch (PPM) is always of concern when performing aortic valve replacement (AVR) in patients with a small aortic annulus. Although bioprosthetic AVR is preferred in patients older than 65 years, we have experienced cases in elderly patients with a small aortic annulus whereby we could not implant small-sized bioprosthetic valves. We have implanted St. Jude Medical Regent (SJMR) mechanical valves (St. Jude Medical, St. Paul, MN, USA) as necessary, even in elderly patients with no aortic annulus enlargement. We investigated our experiences of AVR with SJMR mechanical valves of 21 mm or less in size. Between January 2006 and December 2009, 40 patients underwent AVR with SJMR mechanical valves ≤21 mm in size: 9 patients received 21-mm valves, 19 received 19-mm valves, and 12 received 17-mm valves. The mean age was 65.9 ± 9.5 years, and 25 patients (62.5 %) were 65 years or older. We evaluated the clinical outcome and the echocardiographic data for each valve size. There was no operative or hospital mortality. The mean duration of clinical follow-up was 31.2 ± 17.6 months. During follow-up, there were no hospitalizations due to heart failure. The cumulative valve-related event-free survival was 93 % at 33 months, and the cumulative hemorrhagic event-free survival was 93 % at 33 months and 84 % at 43 months, using the Kaplan–Meier method. At follow-up, the mean values of the measured effective orifice area (EOA) for the 21-, 19-, and 17-mm prostheses were 2.00 ± 0.22, 1.74 ± 0.37, and 1.25 ± 0.26 cm², and the mean measured EOA index (EOAI) were 1.17 ± 0.12, 1.11 ± 0.21 and 0.90 ± 0.22 cm²/m², respectively. A PPM (EOAI ≤0.85) was documented in 5 patients, all of whom had received a 17-mm SJMR valve. AVR with SJMR valves of 21 mm or less in size appears to show satisfactory clinical and hemodynamic results.     

Selection of prosthetic heart valves

Opinion statement Cardiovascular surgery for the repair or replacement of diseased heart valves has continually improved since its introduction in the early 1960s. Despite advances in prosthetic heart valve design, to date there is no valve that is comparable to the native human valve with respect to durability, risk of thrombosis, and overall hemodynamic function. Although bioprosthetic devices are similar to the native valve with respect to thrombogenicity, durability is a significant concern, particularly in younger patients. Approximately 45% of implanted bioprosthetic valves fail at 10 years. In contrast, mechanical prostheses have a significantly lower incidence of structural failure, with an implantation life of greater than 20 years, and are thus more often used for patients under the age of 65. Unfortunately, significant hemodynamic and thrombotic issues have yet to be resolved with the latest generation of mechanical valves. Thus, careful analysis of patient factors and valve-related complications must be considered when treatment of heart valve disease is offered to the patient. The purpose of this review is to discuss the current recommendations for surgical intervention for heart valve disease.     

Quantification of pulmonary autograft characteristics using magnetic resonance imaging

BACKGROUND AND AIM OF THE STUDY: The diameters and distensibility of the native pulmonary root and their effect on pulmonary autograft performance were examined pre- and postoperatively using cardiac ultrasound and magnetic resonance imaging (MRI). METHODS: Eight patients undergoing the Ross procedure were prospectively involved. The diameters of the native aortic, native pulmonary and autograft roots were measured at the level of the annulus, sinus, sinotubular junction and in the main root using MRI through the cardiac cycle. Ultrasound was also used to estimate the degree of regurgitation, both pre- and postoperatively. RESULTS: The pulmonary root implanted into the systemic circulation increased in size but decreased in distensibility significantly at the sinus, sinotubular junction and main root, but not at the annulus. Postoperatively, the pulmonary autograft annulus showed a similar size and distensibility to that of the native aortic annulus. A wide range of aortic annular sizes (22-30 mm) produced clinically competent valves postoperatively. All undersized pulmonary valves showed only trivial regurgitation postoperatively. Although there was no clear correlation between root shape and valve insufficiency, two patients with mild and moderate autograft regurgitation both had divergent pulmonary roots (diameter at sinotubular junction > annulus diameter) preoperatively. CONCLUSION: The pulmonary autograft using the root replacement technique functioned well in all but one case. The shape of the native pulmonary root may be a determinant of early autograft regurgitation, as well as the diameter and the size mismatch between the great arteries.     

Calcification of aortic versus mitral porcine bioprosthetic heart valves: a radiographic study comparing amounts of calcific deposits in valves explanted from the same patient

Calcium detected by radiography was compared in 10 pairs of aortic and mitral glutaraldehyde-treated porcine bioprosthetic heart valves explanted from 10 patients (7 men and 3 women), aged 19 to 68 years (mean 43). Both valves of 6 pairs of valves had undergone primary tissue failure (revealed by cardiac catheterization and angiography) and 1 valve of the other 4 pairs of valves had undergone primary tissue failure. These porcine valves had been implanted from 2 1/4 to 9 years (mean 5 3/4). All 20 explanted valves contained calcium. The grade of calcium was the same in 4 pairs of valves (grade 2+ or 3+), and 1 grade different in 4 pairs of valves (grade 1+ to 4+), with the greater calcium evenly divided between the 2 valve positions. There was more than 1 grade greater mitral valve calcium in 2 pairs of valves (grade 3+ and 4+ mitral vs 1+ and 2+ aortic, respectively). Thus, calcium is usually present in both aortic and mitral valve positions when bioprosthetic valves of this type in either valve position fail as a result of primary tissue failure, and radiographic calcium in porcine bioprosthetic valves is usually similar in grade in both the aortic and mitral valve positions.     

Transcatheter aortic valve in valve implantation with bioprosthetic valve fracture

Valve‐in‐valve transcatheter aortic valve replacement (VIV TAVR) has emerged as a preferable option for high surgical risk patients requiring redo aortic valve replacement. However, VIV TAVR may restrict flow, especially in small native aortic valves. To remedy this, bioprosthetic valve fracture has been utilized to increase the effective orifice area and improve hemodynamics. We present three cases in which bioprosthetic valve fracture was used to increase hemodynamic flow in VIV TAVR procedures.     

Transcatheter valve-in-valve implantation for failing bioprosthetic valves

Transcatheter valve implantation is becoming an alternative to conventional surgical valve replacement in patients at high surgical risk. While experience and acceptance with transcatheter techniques increased rapidly, transcatheter valve implantation within failing bioprostheses has emerged as a new concept (valve-in-valve implantation). Currently, the majority of prostheses implanted in patients are bioprosthetic valves that are expected to degenerate over time. Valve-in-valve implantation provides great utility in high-operative-risk patients since the mortality risk for reoperation can be significantly higher than for first-time isolated valve replacement. Although two current devices are CE Mark approved in Europe for implantation within native valves, off-label clinical implementation of valve-in-valve have been described in numerous case reports. In this article, we provide an overview of transcatheter valve implantation in failing bioprostheses with an emphasis on the aortic position.     

How to Decide Between a Bioprosthetic and Mechanical Valve

Matching the patient to the type of heart valve substitute can be challenging because there is no evidence that the type of heart valve implanted affects survival or quality of life. Mechanical valves are more durable than bioprosthetic valves but are more thrombogenic and require lifelong anticoagulation with warfarin. Age is the most important determinant of bioprosthetic heart valves' durability, and they infrequently fail in patients older than 70 years of age and almost invariably fail in patients younger than 50 years of age. Thus, patients younger than 50 years of age should be advised to have a mechanical valve unless there is contraindication to anticoagulation with warfarin. Patients 50 to 70 years of age can have either bioprosthetic or mechanical valves, but if their lifespans are greater than 20 years, they will likely require reintervention. In reality, the proportion of patients receiving bioprosthetic heart valves has increased in patients of all ages during the past 2 decades, and this trend preceded the development of transcatheter valve implantation to treat failed bioprosthetic valves. Transcatheter valve-in-valve replacement is now the preferred treatment for failed bioprosthetic valves in all positions in older patients, but the long-term results of this approach remain unknown. The shift in favour of bioprosthetic valves in young patients may prove harmful, as more long-term data become available.     

ECHOCARDIOGRAPHIC HEMODYNAMIC ASSESSMENT OF STENTLESS AND SUPERSTENTLESS AORTIC BIOPROSTHESES IN TERMS OF SURVIVAL ADVANTAGE

Porcine xenografts as stentless and recently superstentless bioprosthetic aortic valves are anticipated to cause improved hemodynamics and increase longevity over stented bioprostheses. Stentless valves showed extremely good flow characteristics. Durability has been reported to be better than in stented xenografts accompanied by low gradients, rare and only trivial aortic valve regurgitation. As during the last years the well‐known and attractive aortic bioprostheses stentless St. Jude Toronto SPV and superstentless Shelhigh were often used all over the world including in our institute, we will present their morphologic and functional assessment. Toronto SPV prosthesis requires two suture lines to be implanted. The first row of sutures is between the left ventricular outflow tract and inflow of the valve and the second between the aortic sinuses and the valve. The subcoronary technique of the implantation is intraannular with aortic root as a stent. The diameter of sinotubular junction during diastole is crucial for valve competence and when it exceeds the diameter of the aortic annulus by more than 3 mm, the root is dilated and this valve should not be used. At the completion of the implantation of the valve, the sinotubular junction should not exceed the diameter of the valve. On the contrary, Shelhigh superstentless bioprosthetic aortic valves require one suture line and no sutures are needed in the vicinitiy of the coronary arteries (which might also distort the base of the valve). A composite valve mounted on a superflexible ring has three separate cusps, which allow the best hemodynamic characteristics. Valve implantation is easy with mini or total root replacement and with the possibillity of oversizing the valve conduit by one to three sizes enhancing the hemodynamic advantages. A complete echocardiographic examination included the estimation of maximal and mean transvalvular gradients from transthoracic 5‐chamber view or transesophageal transgaastric view, as well as calculations of effective orifice area by the continuity equation or with planimetry in transesophageal short axis view, especially in the cases of aortic regurgitation. Effective orifice area index, a predictable measure of patient–prosthesis mismatch was calculated at the time of operation or postopertively. Aortic prosthesis valve regurgitation was recorded by pulsed and color Doppler. Left ventricular size, systolic and diastolic function are important clues regarding the severity of regurgitation. Transesophageal assessment of the structure and function of the bioprosthetic stentless valves in short and longitudinal axis provides the evaluation of clinical performance. Measurement of left ventricular mass after aortic valve replacement with both bioprosthetic stentless valves has been done by the truncated ellipse method. Twenty‐eight patients undergoing aortic valve replacement were assigned to receive either Toronto stentless or Shelhigh superstentles aortic valve. Transthoracic and transesophageal echocardiograms were performed after 1 week, 3 months and 6 months, postoperatively. We found maximal systolic transvalvular gradients ranged from 18 to 26 mmHg and mean systolic transvalvular gradients from 8.5 to 12 mmHg with effective orifice area from 1.5 to 2.1cm² without significantly changes in both groups. Thesegradients after 3 and 6 months postoperatively dropped more in the Toronto stentless group, but not significantly hemodinamicly in relation to Shelhigh superstentles group, and the effective orifice area ranged in both groups from 2.4 to 2.8 cm². Left ventricular mass had fallen in both groups but the degree of mass reduction was comparable. Diastolic function has significantly improved in both groups. In conclusion,we had only trivial regurgitation in two cases of Toronto stentless group. Stentless bioprostheses convey hemodynamically and possibly survival benefit through a low incidence of valve‐related complications. Owing to more recent developments of stentless technology with the most advanced anticalcification treatment and superior hemodynamic performance due to maintenance of the normal aortic physiology and flexibility of the aortic root, it is felt that these valves could last 15 years or longer.They will probably provide a useful alternative to aortic homografts in the future.     

Outcomes 15 years after valve replacement with a mechanical versus a bioprosthetic valve: final report of the Veterans Affairs randomized trial

OBJECTIVES: The goal of this study was to compare long-term survival and valve-related complications between bioprosthetic and mechanical heart valves. BACKGROUND: Different heart valves may have different patient outcomes. METHODS: Five hundred seventy-five patients undergoing single aortic valve replacement (AVR) or mitral valve replacement (MVR) at 13 VA medical centers were randomized to receive a bioprosthetic or mechanical valve. RESULTS: By survival analysis at 15 years, all-cause mortality after AVR was lower with the mechanical valve versus bioprosthesis (66% vs. 79%, p = 0.02) but not after MVR. Primary valve failure occurred mainly in patients <65 years of age (bioprosthesis vs. mechanical, 26% vs. 0%, p < 0.001 for AVR and 44% vs. 4%, p = 0.0001 for MVR), and in patients > or =65 years after AVR, primary valve failure in bioprosthesis versus mechanical valve was 9 +/- 6% versus 0%, p = 0.16. Reoperation was significantly higher for bioprosthetic AVR (p = 0.004). Bleeding occurred more frequently in patients with mechanical valve. There were no statistically significant differences for other complications, including thromboembolism and all valve-related complications between the two randomized groups. CONCLUSIONS: At 15 years, patients undergoing AVR had a better survival with a mechanical valve than with a bioprosthetic valve, largely because primary valve failure was virtually absent with mechanical valve. Primary valve failure was greater with bioprosthesis, both for AVR and MVR, and occurred at a much higher rate in those aged <65 years; in those aged > or =65 years, primary valve failure after AVR was not significantly different between bioprosthesis and mechanical valve. Reoperation was more common for AVR with bioprosthesis. Thromboembolism rates were similar in the two valve prostheses, but bleeding was more common with a mechanical valve.     

Hemodynamic performance of the Medtronic ADVANTAGE prosthetic heart valve in the aortic position: echocardiographic evaluation at one year

BACKGROUND AND AIM OF THE STUDY: The study aim was to investigate the echocardiographic Doppler-derived hemodynamic results at one-year follow up at a single center for patients receiving the Medtronic ADVANTAGE aortic prosthetic heart valve. This study was part of a multi-center, prospective clinical evaluation of the ADVANTAGE bileaflet mechanical heart valve. METHODS: Echocardiographic data were obtained one year postoperatively from 40 patients who underwent aortic valve replacement between November 1999 and March 2000. Data collected were in accordance with the Food and Drug Administration guidelines for clinical trials. RESULTS: The in-vivo mean pressure gradients for valves implanted in the aortic position ranged from 11.2 mmHg for size 21 valves to 6.1 mmHg for size 29 valves, and the corresponding in-vivo effective orifice area ranged from 1.5 to 3.6 cm2. CONCLUSION: Early results of the study showed hemodynamic performance of the ADVANTAGE aortic valve to be comparable with that of other bileaflet valves in current clinical use.     

Effect of statins on the progression of bioprosthetic aortic valve degeneration

To date, there is no proved medical therapy able to significantly reduce the degenerative process of biologic prosthetic aortic valves. It has recently been suggested that statins may reduce the progression of native aortic valve stenosis. We examined the effect of statin treatment on bioprosthetic aortic valve degeneration and found a beneficial effect of statins in slowing bioprosthetic degeneration.     

Mid-term results of freestyle aortic stentless bioprosthetic valve: clinical impact of quantitative analysis of in-vivo three-dimensional flow velocity profile by magnetic resonance imaging

BACKGROUND AND AIM OF THE STUDY: The study aim was to investigate the in-vivo flow profiles of a stentless aortic bioprosthetic valve by MRI flow quantification, and to identify the clinical implication of prosthesis size and implantation method. METHODS: Twenty-six patients with a Freestyle stentless aortic bioprosthetic valve were studied using three-dimensional flow velocity profile by MRI, and compared with four patients with a stented aortic bioprosthetic valve and four healthy volunteers. Flow velocity profiles were analyzed quantitatively by the hydromechanics parameter, mean to peak velocity ratio at peak systole and compared with parameters monitored echocardiographically. RESULTS: In larger-sized valves or full root implantation, flow profiles showed an optimal pattern with low gradients, a high mean to peak velocity ratio, and minimum disturbance which approximated that of a normal valve. By contrast, a subset of patients, notably with 21 mm valves and subcoronary implantation, showed suboptimal flow pattern with high gradient and low mean to peak velocity ratio which approximated that of stented valves. The mean to peak velocity ratio was more strongly related to peak velocity than to the indexed effective orifice area. CONCLUSION: Although stentless aortic bioprostheses have excellent hemodynamic performance, some patients show suboptimal results. This seems to occur more often when the subcoronary technique is used, and especially with 21-mm valves. Care must be taken when using the subcoronary technique with a 21-mm valve in patients with a small body surface area.