Claudia Romagnoni

Does the type of suture technique affect the fluid-dynamic performance of bioprostheses implanted in small aortic roots? Results from an in vitro study

BACKGROUND The in vivo hemodynamic performance of a bioprosthesis implanted in an aortic position is affected by the characteristics of the prosthesis and the sizing strategy adopted. Recently, it has been hypothesized that the type of suture used to implant the prosthesis might influence hemodynamics. METHODS Bioprostheses with labeled sizes of 19 mm and 21 mm were implanted in 2 groups of 5 porcine aortic roots, with native annuli of 19 mm and 21 mm, by means of 2 different suture techniques: simple interrupted and noneverting mattress with pledgets. The aortic roots were tested in an in vitro mock loop. The stroke volume imposed by the mock loop was set at 40 mL, and was increased by steps of 15 mL until a stroke volume of 100 mL was attained. Main fluid-dynamic parameters were analyzed. RESULTS At each level of stroke volume, ie, 40 mL, 55 mL, 70 mL, 85 mL, and 100 mL, the mean and peak pressure drops were significantly greater with the noneverting mattress suture with pledgets than with the simple interrupted suture. The effective orifice area behaved accordingly, being significantly smaller in the former case. CONCLUSIONS Our data show that the type of suture technique can influence bioprosthesis performance and that it is reasonable to assume that this is especially true in small annuli (≤ 21 mm). Thus, to optimize prosthesis performance and reduce the incidence of patient-prosthesis mismatch, the role of the suture technique should not be disregarded.

In vitro study of the aortic interleaflet triangle reshaping.

Aortic interleaflet triangle reshaping (AITR) is a surgical approach to aortic valve incontinence that involves placing three stitches at half of the interleaflet triangles height. In this work, the relationship between the actual stitch height and valve functioning, and the safety margin that the surgeon can rely on in applying the stitches were systematically investigated in vitro. AITR surgery was applied to six swine aortic roots placing the stitches empirically at 50%, 60% and 75% of the triangle heights. Then the actual stitch heights were measured and the hydrodynamic performances were evaluated with a pulsatile hydrodynamic mock loop. Actual stitch heights were 45±2%, 61±4% and 79±6%. As compared to untreated conditions, the 50% configuration induced a significant variation in the effective orifice area. With stitches placed at 60%, the mean systolic pressure drop increased significantly with respect to the untreated case, but no significant changes were recorded with respect to the 50% configuration. At 75%, all the hydrodynamic parameters of systolic valve functioning worsened significantly. Summarizing, the AITR technique, when performed in a conservative manner did not induce significant alterations in the hydrodynamics of the aortic root in vitro, while more aggressive configurations did. The absence of a statistically significant difference between the 50% and 60% configurations suggests that there is a reasonably limited risk of inducing valve stenosis in the post-op scenario due to stitch misplacement.

Fluid-dynamic results of in vitro comparison of four pericardial bioprostheses implanted in small porcine aortic roots

OBJECTIVES Small-sized aortic bioprostheses may cause high postoperative gradients. In clinical practice, it is difficult to compare bioprostheses from different manufactures, owing to the discrepancy between the true size and the nominal size of the prosthesis and the inter-patient variability in aortic root characteristics. In vitro studies provide accurate data, and using a system in which it is possible to implant bioprostheses in a true aortic root should enable a fair comparison to be made. The present study compared the four most widely used pericardial stented bioprostheses from different manufacturers surgically implanted in small annulus, to detect any differences in their fluid-dynamic performance. METHODS The four types of bioprostheses, each implanted in a randomized sequence in eight porcine aortic roots, with a native annulus of 2.1 cm, were tested in a mock loop at 65 ml of stroke volume by calculating hydrodynamic parameters, namely mean pressure drop and effective orifice area, performance index, valve resistance and % of energy loss. The prostheses that fitted the aortic root after sizing were as follows: a Magna Ease 21, a Trifecta 21, a Soprano-Armonia 20 and a Mitroflow 23. RESULTS Effective orifice areas were 1.57 ± 0.2, 1.77 ± 0.2, 2.3 ± 0.3 and 1.75 ± 0.2 cm(2) (P < 0.001) for Magna Ease, Mitroflow, Trifecta and Soprano-Armonia, respectively. The mean gradients were 13.2 ± 3, 10.2 ± 3, 6.1 ± 2 and 9.6 ± 2 mmHg (P < 0.001) for Magna Ease, Mitroflow, Trifecta and Soprano-Armonia, respectively. The performance indices were 0.50 ± 0.06, 0.63 ± 0.08, 0.89 ± 0.13 and 0.56 ± 0.07 (P < 0.001) for Magna Ease, Mitroflow, Trifecta and Soprano-Armonia, respectively. The valve resistance, expressed in (dyn*s/cm(5)), was 69 ± 16, 55 ± 13, 33 ± 10 and 51 ± 11 (P < 0.001) for Magna Ease, Mitroflow, Trifecta and Soprano-Armonia, respectively. The percent of energy loss was 13.5 ± 0.5, 10.7 ± 2.5, 6.6 ± 1.6, 10.9 ± 1.8 (P < 0.001) for Magna Ease, Mitroflow, Trifecta and Soprano-Armonia, respectively. CONCLUSION Our study combined the fluid-dynamic reproducibility of the in vitro study with, by using porcine aortic roots, the specificity of surgery. The results confirmed that bioprostheses are inherently obstructive compared with the native aortic valve and showed that bioprostheses with the pericardium outside the stent are more efficient.

Intracardiac visualization of transcatheter aortic valve and valve-in-valve implantation in an in vitro passive beating heart.

![Figure][1] [Video 1][2] Standard TAVI procedure The movie shows the implantation of a 29 mm CoreValve, with views from both the left ventricle and the aorta. ![Figure][1] [Video 2][3] Valve-in-valve procedure The movie shows a valve-in-valve procedure, with a 26 mm CoreValve

A geometric approach to aortic root surgical anatomy

OBJECTIVES The aim of this study was the analysis of the geometrical relationships between the different structures constituting the aortic root, with particular attention to interleaflet triangles, haemodynamic ventriculo-arterial junction and functional aortic annulus in normal subjects. METHODS Sixteen formol-fixed human hearts with normal aortic roots were studied. The aortic root was isolated, sectioned at the midpoint of the non-coronary sinus, spread apart and photographed by a high-resolution digital camera. After calibration and picture resizing, the software AutoCAD 2004 was used to identify and measure all the elements of the interleaflets triangles and of the aortic root that were objects of our analysis. Multiple comparisons were performed with one-way analysis of variance for continuous data and with Kruskal-Wallis analysis for non-continuous data. Linear regression and Pearsons product correlation were used to correlate root element dimensions when appropriate. Students t-test was used to compare means for unpaired data. Herons formula was applied to estimate the functional aortic annular diameters. RESULTS The non coronary-left coronary interleaflets triangles were larger, followed by inter-coronary and right-non-coronary ones. The apical angle is <60° and its standard deviation can be considered an asymmetry index. The sinu-tubular junction was shown to be 10% larger than the virtual basal ring (VBR). The mathematical relationship between the haemodynamic ventriculo-arterial junction and the VBR calculated by linear regression and expressed in terms of the diameter was: haemodynamic ventriculo-arterial junction = 2.29 VBR (diameter) + 47. DISCUSSION Conservative aortic surgery is based on a better understanding of aortic root anatomy and physiology. The relationships among its elements are of paramount importance during aortic valve repair/sparing procedures and they can be useful also in echocardiographic analysis and in computed tomography reconstruction.

Intracardiac Visualization of Transcatheter Mitral Valve Repair in an In Vitro Passive Beating Heart

Transcatheter mitral valve repair has emerged as a feasible and safe alternative in patients with contraindications for surgery or high operative risk.1 Cardiac imaging plays a central role in selecting patients, guiding the procedure, and evaluating the durability of the repair at follow-up. Real-time 3-dimensional transesophageal echocardiography is a key point to visualize and optimize transcatheter mitral valve repair for a good result. However, the chance to clarify, …

Hybrid endovascular treatment of an aortic root and thoracoabdominal aneurysm in a high-risk patient with Marfan syndrome.

This report describes the hybrid endovascular treatment of an aortic root dilatation and a thoracoabdominal aneurysm in a high-risk patient with Marfan syndrome. A 50-year-old male, in hemodialysis for polycystic kidney and polycystic liver, was referred to our department for aortic root dilatation of 5 cm and a 6.3-cm thoracoabdominal aneurysm . He already underwent surgical repair of abdominal aortic aneurysm 10 years ago, complicated by pseudoaneurysm of the proximal anastomosis that had been treated in another center, with an endoprosthesis. The patient underwent aortic root replacement, aortic valve sparing operation, and rerouting of the superior mesenteric artery and celiac trunk to the ascending aorta. The thoracoabdominal aneurysm was excluded with an endoprosthesis few days after the surgical step. The 12-month computed tomography scan confirmed the complete exclusion of the thoracoabdominal aneurysm.

In vitro study of a standardized approach to aortic cusp extension

Purpose Cusp extension technique (CET) is a reparative surgical procedure for restoring aortic valve function by suturing patches to the compromised native leaflets. Its outcomes are strongly dependent on the ability of the surgeon. We proposed and tested a novel approach on an in vitro model, aimed at standardizing and simplifying the surgical procedure. Methods A set of standard pre-cut bovine pericardium patches, available in different sizes, was developed. The surgeon can choose the leaflet-specific patches to be implanted according to the patient anatomy, using a geometrical model of the aortic valve whose inputs are the measured intercommissural distances. The hemodynamic performance of this approach was evaluated on porcine aortic roots in a pulsatile mock loop. Hydrodynamic and kinematic evaluation of the samples was provided. Results After CET, mean and maximum pressure drops were 3.1 ± 1.3 mmHg and 25.4 ± 5.0 mmHg respectively, and EOA was 3.8 ± 0.8 cm2. Static regurgitant fraction and closing volumes were 6.9 ± 2.7% and 7.0 ± 1.5 mL, respectively. All the hemodynamics changes induced by the surgery were statistically significant yet clinically irrelevant as compared to baseline. The treatment also induced a statistically significant alteration in the closing time of the valve. Conclusions Our approach to cusp extension proved to be reliable and effective in restoring valve functioning, without significantly altering the physiological kinematics. The use of pre-cut patches considerably simplified the surgery, increasing standardization and repeatability.

Aortic valve repair: a ten-year single-centre experience

OBJECTIVES Aortic valvuloplasty could represent an alternative to valve replacement resulting in optimal haemodynamic conditions, avoiding anticoagulation and allowing, in young people, normal aortic annulus growth. We analysed our results of aortic valve repair for incompetence due to leaflets and root pathology. METHODS From January 2003 to January 2013, 235 patients affected by aortic valve regurgitation, pure or associated with aortic dilatation, were treated with a combination of the principal leaflet repair techniques and, when necessary, sparing procedures. Of these patients, 218 were considered eligible in this study. All of them were submitted to pre- and postoperative transthoracic echocardiography and pre- and post-repair transoesophageal echocardiography. Follow-up was achieved with periodic echocardiograms and clinical evaluations. RESULTS Eight patients (3.40%) died before discharge. Median clinical and echocardiographic follow-up for all patients was 2.94 (1.41-5.41) years. Mean cross-clamping time was 101.94 ± 40.22 min and mean hospital stay was 10 ± 6.69 days. Kaplan-Meier freedom from aortic regurgitation >2 and freedom from aortic valve replacement were, respectively, 92.9 ± 2.8 and 94.5 ± 2.5% at 9.24 years: 6 patients (2.75%) were reoperated on with aortic valve replacement for severe aortic regurgitation. We also observed a good effect of aortic surgery on the left ventricle: the end-diastolic volume decreased from 137.89 ± 50.23 ml in the preop to 105.17 ± 31.19 ml at follow-up. CONCLUSIONS Aortic valve leaflet repair seems to be a good and feasible option for selected patients, both alone or associated with an aortic sparing technique concerning long-term results.

Design of a simple coronary impedance simulator for the in vitro study of the complex coronary hemodynamics

Several novel approaches were recently developed to treat aortic root pathologies. The alteration induced by some of these approaches to the biomechanics of the aortic root could possibly affect the coronary perfusion, compromising the procedural outcome. In this scenario, the need to replicate in vitro the coronary flow pattern in physiological and pathological conditions is becoming crucial for the functional assessment of novel devices and techniques. This article describes the design of an easy-to-use, left-and-right coronary impedance simulator, coupled with native aortic roots for in vitro pulsatile tests. Experiments were performed in order to assess the performances of the coronary impedance simulator when coupled with healthy aortic valves (cardiac output: 3.8  ±  0.26 l min-1; mean systemic pressure: 95  ±  1.3 mmHg; mean coronary flow rate: 272  ±  13.4 ml min-1) or with regurgitant valves (cardiac output: 1.9  ±  0.24 l min-1; mean systemic pressure of 45  ±  3.3 mmHg; mean coronary flow rate:149  ±  21.9 ml min-1). The acute systemic response to valve regurgitation was also replicated, with increased beat rate and afterload, aimed at restoring the systemic pressure (cardiac output: 2.5  ±  0.23 l min-1; mean systemic pressure of 109  ±  6.1 mmHg; mean coronary flow rate: 262  ±  35.5 ml min-1). In the test conditions, the system was able to replicate in vitro the main determinants of the coronary circulation with physiological left/right coronary flow rate repartition, and a realistic interaction between coronary and systemic hemodynamics. The coronary simulator appears to be a suitable platform to study and optimize the interactions between novel approaches to aortic valve pathology and the coronary perfusion.