A Novel Method for Optical High Spatiotemporal Strain Analysis for Transcatheter Aortic Valves In Vitro.

The transcatheter aortic valve implantation (TAVI) valve is a bioprosthetic valve within a metal stent frame. Like traditional surgical bioprosthetic valves, the TAVI valve leaflet tissue is expected to calcify and degrade over time. However, clinical studies of TAVI valve longevity are still limited. In order to indirectly assess the longevity of TAVI valves, an estimate of the mechanical wear and tear in terms of valvular deformation and strain of the leaflets under various conditions is warranted. The aim of this study was, therefore, to develop a platform for noncontact TAVI valve deformation analysis with both high temporal and spatial resolutions based on stereophotogrammetry and digital image correlation (DIC). A left-heart pulsatile in vitro flow loop system for mounting of TAVI valves was designed. The system enabled high-resolution imaging of all three TAVI valve leaflets simultaneously for up to 2000 frames per second through two high-speed cameras allowing three-dimensional analyses. A coating technique for applying a stochastic pattern on the leaflets of the TAVI valve was developed. The technique allowed a pattern recognition software to apply frame-by-frame cross correlation based deformation measurements from which the leaflet motions and the strain fields were derived. The spatiotemporal development of a very detailed strain field was obtained with a 0.5 ms time resolution and a spatial resolution of 72 µm/pixel. Hence, a platform offering a new and enhanced supplementary experimental evaluation of tissue valves during various conditions in vitro is presented.

Transfemorally or transapically deployed Sapien Edwards bioprosthesis is always deformed.

OBJECTIVE: To study the impact of femoral compared to apical access on the Sapien-Edwards (SE) prosthesis deployment and geometry in patients treated with transcatheter aortic valve implantation (TAVI) for aortic stenosis. BACKGROUND: SE prosthesis deformation exists after its deployment through transfemoral (TF-TAVI) approach. However, no study comparing the deformation between TF-TAVI and transapical (TA-TAVI) approaches has yet been published. METHODS: Forty consecutive patients received TAVI with the SE prosthesis (TF-TAVI n = 25; TA-TAVI n = 15). A fluoroscopic analysis of the prosthesis was then performed. The stent frame geometry was assessed during deployment in the profile view, and after implantation in the profile and frontal views. RESULTS: Expansion kinetics revealed a triphasic stent deployment with both approaches; the aortic extremity being the first to open. After implantation, on the profile view, the stent shape was never rectangular (therefore never cylindrical) in both groups. It had a biconic shape in most of the patients (76% vs. 93.3% for TF-TAVI and TA-TAVI patients, respectively, P = 0.224) with a wider aortic extremity relative to the ventricular one. The frontal view analysis showed that circular deployment of the stent was never achieved. A greater leaflet to stent mismatch was noted in TA-TAVI patients, however, the difference was not statistically significant (12% vs. 33.3%, P = 0.126). CONCLUSION: Fluoroscopically assessed, the geometry of SE prosthesis was never cylindrical after deployment, whatever the access for implantation was. Longitudinal deformation was greater after TF-TAVI whereas leaflet to stent mismatch tended to be more pronounced after TA-TAVI.

Elliptical shape of a SAPIEN XT prosthesis deployed in a patient with bicuspid aortic valve stenosis.

Transcatheter aortic valve implantation (TAVI) has been shown as an effective procedure in patients considered at high risk for surgery. Aortic valve bicuspidy, as encountered in up of 50% of patients with severe aortic stenosis, has been considered a contraindication to TAVI. One reason for this is that stent deformation is likely to occur after prosthesis deployment, but this has been refuted by recent observations with the SAPIEN prosthesis. Herein is reported the first case of a severely deformed SAPIEN XT prosthesis after TAVI in a patient with severe symptomatic aortic stenosis, and known to have a bicuspid native aortic valve.

Complications of the access during aortic valve implantation through transfemoral access.

BACKGROUND: Aortic valve implantation (AVI) is a booming therapeutic option in high-risk patients with calcific aortic stenosis. Retrograde femoral approach drawbacks include vascular complications owing to the size of the introduction system (22- and 24-F).The aim of this study was to retrospectively analyze the incidence and the treatment of vascular complications in the first 2 years of transfemoral AVI experience with the first generation of Edwards SAPIEN transcatheter heart valves. METHODS: Since December 2007, AVI has been performed in 71 patients, 21 times by the transapical route and 50 times by the transfemoral route through an inguinal approach with the first generation of Edwards SAPIEN transcatheter heart valves (23 and 26 mm). The incidence and the treatment of vascular complications were evaluated as main criteria for transfemoral AVI. RESULTS: All the procedures could be successfully performed by a femoral route, except for three cases when the introducing device could not be fixed on the thoracic aorta because of vascular access problems. Vascular access-related complications occurred in nine patients (18%), including three iliac dissections, two aortic dissections, three femoral lesions, and one thoracic aorta rupture. These complications were treated either in a conservative way (n = 2), or in an endovascular way using a contralateral approach (n = 3), or surgically through an inguinal approach (n = 3). A traumatic rupture of the thoracic aorta resulted in the death of a female patient. CONCLUSION: In our experience, transfemoral AVI gives a satisfying technical success rate in the selected patients. The incidence of complications involving the vascular access remains an important limitation of this new technique. Although a conservative or endovascular treatment can be applied in most cases, improving the introduction devices is highly expected because it would reduce the complications rate of vascular access.

Postimplant biological aortic prosthesis degeneration: challenges in transcatheter valve implants.

Surgical aortic valve replacement (SAVR) is highly effective and can be achieved with relatively low risk in patients with severe aortic stenosis. Bioprostheses have been used most frequently during the past 60 years. However, the function of biological valves usually declines after 10-15 years from implant when structural valve degeneration occurs often mandating a reoperation once valve dysfunction becomes haemodynamically significant. Known for many years by surgeons and cardiologists taking care of patients with SAVR, the issue of postimplant structural valve degeneration has been recently highlighted also in patients with transcatheter aortic valve implant (TAVI). There is growing concern that TAVI valves exhibit structural valve degeneration due to inherent challenges of the deployment mode. The impact on postimplant degeneration of TAVI valves compared to SAVR has still to be understood and defined. Based on the ongoing process of expanding TAVI indications, several potential shortcomings and caveats, learned during the last 60 years of SAVR experience, should be taken into consideration to refine this technique.

Traumatic leaflet injury: comparison of porcine leaflet self-expandable and bovine leaflet balloon-expandable prostheses.

OBJECTIVES: The main goal of this study was to compare the occurrence of post-deployment leaflet injury between prostheses made of porcine and bovine pericardium. METHODS: Two types of prostheses, self-expandable prostheses with porcine pericardial leaflet on one side and balloon-expandable prostheses with bovine pericardial leaflet on the other side, were used. In each group, crimped prostheses were compared with control non-crimped prostheses. Following a 15-min period of crimping, prostheses were deployed, and their leaflets were removed and subjected to analyses. The analyses included determination of global and local hydraulic conductance of the leaflets, leaflet plasma insudation and microscopic analysis. The results were expressed as percentage (standard error of the mean) or median (interquartile range). RESULTS: A significant increase in the global hydraulic conductance was only observed in the crimped balloon-expandable prostheses: 20.1 (15.5-41.2) ml/h/m2/mmHg vs 12.3 (9.0-15.6) ml/h/m2/mmHg (P = 0.021). Similarly, areas of marked staining (a marker of local hydraulic conductance) were only seen in the bovine pericardium balloon-expandable prostheses. The incidence of leaflet plasmatic insudation was increased in the crimped prostheses compared with the control prostheses. The microscopic study revealed a higher occurrence of traumatic lesions in the crimped prostheses in comparison with the control prostheses: 33.3 ± 21.1% vs 5.5 ± 5.5% (P = 0.039) and 44.4 ± 20.5% vs 5.5 ± 5.5% (P = 0.017) in the bovine and the porcine leaflets, respectively. CONCLUSIONS: Post-deployment leaflet injury occurred in both types of prostheses. However, alteration of the global and local hydraulic conductance was important in the bovine pericardium balloon-expandable prostheses.

Long-term results of mitral valve repair in active endocarditis.

BACKGROUND: Several investigators have reported the feasibility of mitral valve repair in active endocarditis, but the long-term results are still unknown. METHODS AND RESULTS: We reviewed 37 consecutive patients who underwent mitral valve repair with the Carpentier technique for active endocarditis in our center between 1989 and 1994. This repair involved prosthetic annuloplasty in 31 patients (84%), valve resection in 31 (84%), chordal shortening or transposition in 19 (51%), pericardial patch in 16 (43%), and direct suture of leaflet perforation in 4 (11%). Associated procedures were primarily aortic valve repair or replacement in 11 (30%) and tricuspid repair in 2 (6%). Early complications included 1 operative death (3%; 95% CI, 0 to 15.5) and 1 reoperation for pericardial patch dehiscence. Recurrence of endocarditis was observed in 1 patient (3%; 95% CI, 0 to 16). The 10-year survival rate and freedom from mitral valve reoperation were 80% (95% CI, 66 to 94) and 91% (95% CI, 81 to 100), respectively. At 10 years, most patients (96%) were in good functional status (NYHA class I to II) with no or trivial mitral regurgitation (92%) on echocardiography. CONCLUSIONS: Mitral valve repair using Carpentier's techniques in patients with active endocarditis offers very good long-term results with a low rate of recurrence or reoperation.

Management of commissural lesions in native mitral valve endocarditis: long-term results of valve repair and partial homograft replacement.

BACKGROUND AND AIM OF THE STUDY: Commissural lesions in the context of native mitral valve endocarditis are a technically challenging condition for conservative surgery. Herein are reported the authors' 10-year results for mitral valve repair (MVRep) or partial homograft replacement (PHR) performed in this setting. METHODS: Data were reviewed from 19 consecutive patients who underwent MVRep using either Carpentier's technique (n = 14) or PHR (n = 5) for endocarditis at the authors' institution between 1989 and 1994. RESULTS: There was one operative death (5%; 95% CI 0-15.5%). Two reoperations were performed in each subgroup for recurrence of endocarditis (n = 2) and mitral valve failure (n = 2). The 10-year survival rate and freedom from mitral valve reoperation were 95% (95% CI 84-100%) and 78% (95% CI 59-97%), respectively. At 10 years, 13 (93%) surviving and non-reoperated patients were in good functional status (NYHA class I-II), and 14 (100%) were in sinus rhythm. Although echocardiographic results were excellent in the MVRep group, all PHR patients had moderate or severe mitral valve dysfunction. CONCLUSION: Commissural reconstruction using Carpentier's techniques demonstrated excellent long-term results in patients with native mitral valve endocarditis. In contrast, the results for PHR were rather disappointing.

Exhaled nitric oxide and acute lung injury in a rat model of extracorporeal circulation.

Exhaled nitric oxide (NO) concentration, a marker of pulmonary inflammation, has been shown to be elevated in various models of acute lung injury (ALI). This study was undertaken to evaluate the pulmonary NO production in a rat model of postextracorporeal circulation (ECC) ALI. Wistar rats underwent either a partial femorofemoral ECC in normothermia for 3 h (n = 10) or a sham procedure (n = 10). The extracorporeal circuit consisted of a roller pump and a membrane oxygenator. Exhaled NO concentration was monitored with a chemiluminescence analyzer. After sacrifice, lungs were harvested for microscopic studies and to analyze the inducible nitric oxide synthase (iNOS) activity and expression (Western blot). ECC was responsible for an ALI characterized by a decreased arterial blood oxygen saturation (88.9% [51.7-94.2] vs. 93.7% [91.4-98.6] P = 0.005) and pulmonary histological changes (marked alveolar neutrophil infiltration; interstitial edema; intraalveolar hemorrhage). The lung injury score was significantly higher in the ECC group (n = 5; 3.0 [2-4]) in comparison to the sham group (n = 5; 1.0 [0-2]). Exhaled NO concentration remained stable throughout the experiment in all sham rats whereas it significantly increased in the ECC group from baseline (2 ppb [1-5]) until the end of experiment (33.5 ppb [1-47]). Lung iNOS activity and expression were also significantly increased in the ECC group. An increase in exhaled NO, however, did not correlate with the decrease in arterial oxygen pressure. ECC was responsible for an ALI in rats and for an elevated pulmonary NO production. Determination of the relationship between exhaled NO and the severity of the inflammatory process in ALI will require further studies.

Exhaled carbon monoxide and inducible heme oxygenase expression in a rat model of postperfusion acute lung injury.

OBJECTIVE: Expression of inducible heme oxygenase has been shown to be increased in various visceral inflammatory disorders, which may confer a protective role. The purpose of our study was to determine whether the expression of inducible heme oxygenase was up-regulated within lungs in a rat model of extracorporeal circulation. METHODS: Wistar rats underwent either a partial femoro-femoral extracorporeal circulation in normothermia for 3 hours (n = 5) or a sham procedure (n = 5). Exhaled carbon monoxide concentration was monitored with an infrared analyzer. After the rats were killed, lungs were harvested for determination of heme oxygenase activity and inducible heme oxygenase expression (by Western blot and immunohistochemistry). Lung injury was also assessed by arterial blood gas analysis and microscopic study. RESULTS: Extracorporeal circulation was responsible for a lung injury characterized by decreased arterial blood oxygen saturation and typical morphologic findings (marked alveolar neutrophil infiltration; interstitial edema). Exhaled carbon monoxide concentration remained stable throughout the experiment in all sham rats, whereas it increased after extracorporeal circulation (from 0.16 +/- 0.05 ppm at baseline to 0.7 +/- 0.2 ppm at end of experiment; P =.0001). Pulmonary heme oxygenase activity and inducible heme oxygenase content (assessed by Western blot) were increased within lungs of rats that underwent extracorporeal circulation. Immunohistochemistry revealed that the expression of inducible heme oxygenase was mainly localized to inflammatory cells. CONCLUSIONS: Post-extracorporeal circulation acute lung injury in rats was associated with an increased expression of inducible heme oxygenase, the functional significance of which remains to be determined.

Increased endogenous carbon monoxide production in severe sepsis.

OBJECTIVE: A comparison was made between the endogenous carbon monoxide (CO) production in mechanically ventilated critically ill adult patients with, and those without, severe sepsis. DESIGN: Prospective comparative study. SETTING: Medical ICU in a community hospital. PATIENTS: Twenty-four patients with severe sepsis of various etiologies and five control patients with varying diagnoses. INTERVENTION: CO concentration was determined with an infrared CO analyzer on exhaled breath collected at the outlet of the ventilator. Endogenous CO production was estimated by the lung CO excretion rate measured at steady state. MEASUREMENTS AND MAIN RESULTS: : Endogenous CO production was higher in the sepsis group during the first 3 days of treatment in comparison to the control group (10.9+/-5 (SD) microl/kg per h on day 1, 7.8+/-4.9 microl/kg per h on day 2 and 6.9+/-4.7 microl/kg per h on day 3 versus 2.1+/-0.5 microl/kg per h; p<0.01 for each comparison). Survivors of sepsis had a significantly higher endogenous CO production on day 1 compared to non-survivors (14.7+/-5.3 versus 8.5+/-3.3 microl/kg per h; p=0.02). CONCLUSION: Endogenous CO production was significantly higher in mechanically ventilated patients suffering from severe sepsis. Further studies are required in order to determine the mechanism(s) and the functional significance of this increase.

Aortic cusp extension valvuloplasty for rheumatic aortic valve disease: midterm results.

BACKGROUND: The surgical management of rheumatic aortic insufficiency in the young remains problematic owing to the drawbacks of prosthetic valve replacement at this age. In young foreign patients, for whom long-term anticoagulation therapy is unavailable, we have used a glutaraldehyde preserved autologous pericardium cusp extension technique to repair rheumatic aortic valve insufficiencies resulting from cusp retractions. METHODS: From September 1992 to December 2000, 89 consecutive patients with a mean age of 16 +/- 5 years underwent triple pericardial aortic cusp extension valvuloplasty. Eighty patients had pure aortic insufficiency, 9 had mixed aortic disease. Twenty-nine patients (33%) had isolated aortic valve disease and 60 patients (69%) had combined aortic and mitral valve disease with significant tricuspid valve disease in 21 (24%). Aortic repair consisted of free edge aortic cusp extension using three rectangular strips of glutaraldehyde stabilized autologous pericardium. Twenty-nine patients (33%) underwent an isolated aortic repair, 39 patients (44%) underwent combined aortic and mitral procedures (34 mitral repairs, 3 mitral homografts, and 2 prosthesis replacements), and 21 patients (23%) underwent a triple valve repair. RESULTS: The hospital mortality was 2.2%. Primary failure of the aortic repair requiring immediate reoperation occurred in 2 patients. During follow-up (mean of 62 +/- 22 months) 1 patient died and 7 underwent redo valvular surgery. At 5 years the actuarial survival rate was 96.4%, and 92.1% of the patients were free from redo valvular surgery. At 7 years 90% of the patients were free from valve-related complications. Among the 76 patients free from redo valvular surgery at follow-up, 6 had deterioration of the repair resulting in grade II aortic and mitral insufficiencies. CONCLUSIONS: Our midterm results of glutaraldehyde stabilized autologous pericardial aortic cusp extension are encouraging and suggest that this technique should be considered as a viable alternative palliative procedure in a young rheumatic population, allowing for growth of the annulus and delaying to a less critical period the need for the lifelong anticoagulation therapy required for a prosthetic mechanical valve.

Comparison of two antiplatelet therapy strategies in patients undergoing transcatheter aortic valve implantation.

Dual antiplatelet therapy is commonly used in patients undergoing transcatheter aortic valve implantation (TAVI), but the optimal antiplatelet regimen is uncertain and remains to be determined. The objective of this study was to compare 2 strategies of antiplatelet therapy in patients undergoing TAVI. A strategy using monoantiplatelet therapy (group A, n = 164) was prospectively compared with a strategy using dual antiplatelet therapy (group B, n = 128) in 292 consecutive patients undergoing TAVI. The primary end point was a combination of mortality, major stroke, life-threatening bleeding (LTB), myocardial infarction, and major vascular complications at 30 days. All adverse events were adjudicated according to the Valve Academic Research Consortium. The primary end point occurred in 22 patients (13.4%) in the group A and in 30 patients (23.4%) in the group B (hazard ratio 0.51, 95% confidence interval 0.28 to 0.94, p = 0.026). LTB (3.7% vs 12.5%, p = 0.005) and major bleedings (2.4% vs 13.3%, p <0.0001) occurred less frequently in the group A, whereas the incidence of stroke (1.2% vs 4.7%, p = 0.14) and myocardial infarction (1.2% vs 0.8%, p = 1.0) was not significantly different between the 2 groups. The benefit of a strategy using mono versus dual antiplatelet therapy persisted after multivariate adjustment and propensity score analysis (hazard ratio 0.53, 95% confidence interval 0.28 to 0.95, p = 0.033). In conclusion, a strategy using mono versus dual antiplatelet therapy in patients undergoing TAVI reduces LTB and major bleedings without increasing the risk of stroke and myocardial infarction. The results of our study question the justification of dual antiplatelet therapy and require confirmation in a randomized trial.

Crimping and deployment of balloon-expandable valved stents are responsible for the increase in the hydraulic conductance of leaflets.

OBJECTIVES: Leaflet injury has been documented to occur during the deployment of valved stents (VSs). The pathological aspects, however, of this injury are difficult to quantify. Conversely, the hydraulic conductance of a (pericardial) membrane may be easily determined. The impact of crimping and deployment of VS on this parameter was therefore investigated. METHODS: Bovine pericardial square (25 × 25 mm) patches were placed within a pressure chamber and their hydraulic conductance was determined. The influence of the pressure gradient and tissue thickness on this parameter was analysed. Six balloon-expandable VS were constructed. The hydraulic conductance of their bovine pericardial leaflets was determined before and after VS crimping and deployment in four of them. Pericardial leaflets of non-crimped VS were used as controls. RESULTS: Hydraulic conductance increased insignificantly with the pressure level within the chamber: from 128 ± 26.9 ml/h/m(2)/mmHg at a pressure of 50 mmHg to 232.3 ± 51.9 ml/h/m(2)/mmHg at a pressure of 250 mmHg (P = 0.117). Hydraulic conductance was not correlated to pericardial thickness, for thickness measurements ranging from 0.34 to 0.76 mm. The hydraulic conductance of VS leaflets significantly increased immediately after crimping from 45.2 ± 7.6 to 667.9.0 ± 527.2 ml/h/m(2)/mmHg (P < 0.001). This increase was still observed 24 h after VS deployment. No change in hydraulic conductance occurred in the control group. CONCLUSIONS: The determination of the hydraulic conductance of pericardial patches was easy to perform, reproducible and not influenced by tissue thickness. The hydraulic conductance of pericardial leaflets dramatically increased after VS crimping and deployment. This parameter might be, in the future, a useful noninvasive tool in studying leaflet trauma.

Traumatic leaflet injury during the use of percutaneous valves: a comparative study of balloon- and self-expandable valved stents.

OBJECTIVES: No comparison of balloon- or self-expandable valved stents (VSs) regarding tissue injury (if any) has been reported yet. The objective was to evaluate the occurrence and compare the severity of traumatic injury to leaflets from balloon- or self-expandable VSs. METHODS: Twelve homemade VSs were used for this experiment. These three-leaflet bovine pericardial bioprostheses had either a stainless steel (Group A) or a nitinol stent (Group B). After a 30-min period of compression (external diameter of VS reduced to 7 mm), the prostheses were deployed by balloon inflation (Group A) or by unsheathing (Group B). After H&E staining, pericardial leaflets were subsequently analyzed qualitatively and quantitatively for microscopic lesions. Non-crimped pericardial leaflets were used as a control group (Group C). RESULTS: All deployed VSs had microscopic lesions evocating traumatic injury to pericardial leaflets. Transverse fractures and longitudinal cleavages were the two main lesions encountered. Transverse fractures (no. per field) were significantly more frequent in the VS in comparison with the control group: 5 (range: 0-13), 4 (range: 0-9) and 0 (range: 0-1) in Groups A, B and C, respectively (P < 0.001). Cleavages (no. per field) were also more frequent with balloon-expandable VSs compared with self-expandable VSs [3 (range: 0-7) vs 1(range: 0-8); P = 0.03]. CONCLUSIONS: Traumatic injury to the pericardial leaflets does occur during crimping and deployment of balloon- or self-expandable VSs. Injury may be more severe with the balloon-expandable VSs. The impact of such an injury on prosthesis durability requires a further investigation.

Detecting aortic valve bicuspidy in patients with severe aortic valve stenosis: high diagnostic accuracy of colour Doppler transoesophageal echocardiography.

OBJECTIVES: The diagnostic accuracy of multiplane bi-dimensional transoesophageal echocardiography (TEE) in detecting aortic valve bicuspidy is good, but is less reliable when the leaflets are moderately or severely calcified. We hypothesized that systolic colour Doppler analysis might improve the accuracy of diagnosing aortic bicuspidy by TEE in patients with severe symptomatic aortic stenosis (AS). METHODS: Two colour Doppler images of a stenotic aortic valve were defined in a preliminary study using multiplane TEE. In type I, the valve opening had a linear, angular or 'hanger-like' configuration and in type II it was more star-like or 'stellar'. The accuracy of this classification in detecting bicuspidy was evaluated. Fifty-one patients (mean age 71 years (range 40-90 years); 52% male) with severe symptomatic AS (defined as aortic valve area ≤1 cm(2)), requiring surgical aortic valve replacement, were included in this prospective study. The surgical findings were compared with the echocardiographic data. RESULTS: The incidence of aortic bicuspidy was 43%. The presence of type I colour Doppler configuration was significantly higher for bicuspid than for tricuspid aortic valves (95.5 vs 3.5%, respectively; P < 0.001). Diagnostic accuracy in detecting bicuspidy was high (sensitivity 95.5%; specificity 96.5%; positive predictive value 95.5%). Intra- and inter-observer agreements were excellent (Kappa coefficient = 0.88 and 0.92, respectively). CONCLUSIONS: Aortic valve bicuspidy may be accurately diagnosed by colour Doppler valve analysis during TEE in patients with severe AS. Larger prospective studies are required to confirm our results.