Monica Contino

In vitro hemodynamics and valve imaging in passive beating hearts.

Due to their high complexity, surgical approaches to valve repair may benefit from the use of in vitro simulators both for training and for the investigation of those measures which can lead to better clinical results. In vitro tests are intrinsically more effective when all the anatomical substructures of the valvular complexes are preserved. In this work, a mock apparatus able to house an entire explanted porcine heart and subject it to pulsatile fluid-dynamic conditions was developed, in order to enable the hemodynamic analysis of simulated surgical procedures and the imaging of the valvular structures. The mock loops hydrodynamic design was based on an ad-hoc defined lumped-parameter model. The left ventricle of an entire swine heart was dynamically pressurized by an external computer-controlled pulse duplicator. The ascending aorta was connected to a hydraulic circuit which simulated the input impedance of the systemic circulation; a reservoir passively filled the left atrium. Accesses for endoscopic imaging were located in the apex of the left ventricle and in the aortic root. The experimental pressure and flow tracings were comparable with the typical in vivo curves; a mean flow of 3.5±0.1l pm and a mean arterial pressure of 101±2 mmHg was obtained. High-quality echographic and endoscopic video recordings demonstrated the systems excellent potential in the observation of the cardiac structures dynamics. The proposed mock loop represents a suitable in vitro system for the testing of minimally-invasive cardiovascular devices and surgical procedures for heart valve repair.

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.

Bicuspid aortic valve: differences in the phenotypic continuum affect the repair technique

OBJECTIVE Bicuspid aortic valve (BAV) may be considered in the context of a phenotypic continuum of the aortic valve configuration, ranging from severe forms of unicuspid valve to rare forms of quadricuspid valve. In this article, we report our results with BAV repair using surgical techniques tailored to the specific features of the BAV phenotypic continuum. PATIENTS AND METHODS Between September 2003 and May 2009, 31 patients with BAV (mean age 49.9+/-17.3 years; five female; 26 male) were prospectively enrolled for aortic valve repair. The surgical strategy was tailored depending on the anatomical and structural characteristic of the BAV continuum: type 1 real bicuspid (five patients), type 2 bicuspid with raphe (24 patients) and type 3 clefted bicuspid (two patients). An echocardiographic analysis was performed preoperatively, postoperatively, at discharge and every 6 months during follow-up. Kaplan-Meier analysis was used to assess the freedom from re-operation. RESULTS One patient died in the intensive care unit due to aortic wall rupture. After BAV repair there was an increase of leaflet coaptation length (from 2.0+/-0.5 mm to 8.2+/-1.9 mm, p<0.01) and a decrease of the diameters of the virtual basal ring (from 24.6+/-3.6 mm to 21.5+/-0.71 mm, p<0.01), of the aortic root (from 43.12+/-13.23 mm to 31.0+/-3.2 mm, p<0.01) and of the sino-tubular junction (from 40.1+/-6.95 mm to 33.5+/-9.19 mm, p<0.05). The aortic regurgitation echocardiographic grade > or =II was found preoperatively in 30 patients and postoperatively in one patient (p<0.01). Six patients underwent an associated aortic valve-sparing procedure (three re-implantation and three remodelling). Kaplan-Meier analysis showed a 96.6% freedom from re-operation at 5 years, with a single new repair procedure and a 100% freedom from aortic valve replacement. CONCLUSIONS BAV repair provides a feasible therapeutic option in selected patients with good medium-term results. The surgical techniques should be applied after a careful analysis of the BAV considered in the context of the phenotypic continuum.

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.

Commissural repositioning in bicuspid aortic valve repair with Valsalva graft

Bicuspid aortic valve (BAV) is the most common congenital cardiac defect, with an estimated prevalence between 0.5% and 2% (1); this pathology is often associated with aortic root and ascending aorta dilation due to structural abnormalities such as decreased fibrillin, elastin fragmentation and apoptosis (1,2).

Optilene, a new non-absorbable monofilament is safe and effective for CABG anastomosis. OPTICABG - A prospective international, multi-centric, cohort study

Introduction Coronary artery bypass grafting (CABG) is performed to improve quality of life and to reduce cardiac-related mortality and morbidity in patients with coronary artery disease (CAD). The aim of the present observational study was to assess the performance of a new suture material (Optilene) for anastomosis construction in CABG surgery using a routine clinical procedure. Performance was assessed using the incidence of major adverse cardiac and cerebrovascular events (MACCE). Methods The study was designed as an international, multi-centre, prospective cohort study to evaluate the safety and efficacy of a new non-absorbable monofilament for CABG surgery compared to data published in a previous meta-analysis. Optilene suture was used to create the distal and proximal coronary artery anastomoses. The primary endpoint was the cumulative MACCE rate up to discharge. Secondary parameters were intraoperative handling of the suture material and QoL up to 3 months after surgery. Patients were examined 30 days and 3 months postoperatively. Results In total, 199 patients were enrolled in 3 centres in Europe. The cumulative CABG adverse event rate up to the day of discharge was 3%, in contrast to the 8.46% given by the data generated by Nalysnyk et al. A t-test showed that our CABG rate was significantly lower. QoL significantly increased from preoperatively until 3 months after surgery. Ease of handling the suture material was rated as very good. Conclusion Optilene suture material represents a safe and effective alternative to existing sutures used in CABG surgery for anastomosis construction.