Leaflet kinematics after the Yacoub and Florida-sleeve operations: results of an in vitro study.

OBJECTIVES: The Florida-sleeve is a valve-sparing technique that causes minimal interference to leaflet kinematics and aortic root dynamism. The aim of this in vitro study was to evaluate the effects of the Florida-sleeve and Yacoub techniques on aortic leaflet kinematics. METHODS: Two groups of 6 whole porcine hearts were treated with either the Florida-sleeve technique or the Yacoub technique and tested in a pulsatile loop. Valve fluid dynamics, coronary flow analysis and valve echocardiograms were performed both before and after the procedures. RESULTS: Both procedures showed no difference in rapid valve opening time as compared with their respective baseline values. The Florida-sleeve procedure showed a shorter slow closing time (192 ± 19 ms vs baseline 244 ± 14 ms, P = 0.016) and increased slow closing velocity (-1.5 ± 0.4 cm/s vs baseline -0.8 ± 0.4 cm/s, P = 0.038). In the rapid valve closing phase, the Yacoub procedure showed a trend towards slower closing valve velocity (-16 ± 9 cm/s vs baseline -25 ± 9 cm/s, P = 0.07). The Yacoub procedure showed larger leaflet displacement at the end of the slow valve closing time that was 2.0 ± 0.5 cm vs baseline 1.5 ± 0.3 cm, P = 0.044. When comparing the Florida-sleeve and Yacoub procedures, the former showed statistically significant shorter slow valve closing time (P = 0.017). CONCLUSIONS: This study showed that the Florida-sleeve technique alters the slow closing phase of the aortic valve leaflet kinematics when compared with both the normal baseline and Yacoub procedure, while the latter showed a larger leaflet displacement before the rapid closing valve phase.

Surgery from the future: Performing a safe valve-in-valve explantation.

As the number of young and relatively low-risk patients undergoing transcatheter aortic valve implantation increases, the number who will require open heart surgery months or years later will also increase. Only a few cases of late transcatheter heart valve explantation (without root replacement) have been reported in the literature, and this rare procedure can be surgically very challenging. In this video tutorial we present the case of a patient with a valve-in-valve subacute thrombosis, and we describe the surgical technique for valve explantation.

Preliminary Results of Debranch-First Technique in Frozen Elephant Trunk Procedures.

BACKGROUND: To evaluate the outcomes of frozen elephant trunk (FET) procedures performed with a customized graft that allows debranch-first technique with continuous antegrade cerebral perfusion and early distal aortic and myocardial reperfusion. METHODS: Between 2016 and 2018 34 patients (30 men; median age, 59.7 years) were enrolled in an ambispective single-center study called FET Optimization (clinicaltrials.gov: NCT03600077). The patients underwent FET procedure using a novel modified E-Vita graft (JOTEC GmbH, Hechingen, Germany) plus graft with 2 dedicated reperfusion branches with debranch-first technique. Mortality and morbidity were primary endpoints. Secondary endpoints were overall duration of cardiopulmonary bypass, debranching, limb ischemia, cardiac ischemia, cerebral perfusion, and amount of aortic coverage. RESULTS: No deaths at 30 days were recorded, and the major adverse event (grade ≥ 2) rate was 33% (11 patients) including 1 (3%) nondisabling stroke and 1 (2.9%) permanent spinal cord ischemic event. Proximal FET collar anastomosis were in zone 0 (68%) or zone 1 (32%). Median cardiopulmonary bypass duration was 165 minutes (range, 144-185), distal aortic ischemic time 38 minutes (range, 32-45), and cardiac ischemic time 74 minutes (range, 62-94). The time of distal aortic ischemia was shorter in nonobese patients (27 vs 49 minutes, P = .043) and in zone 0 (23 cases) vs zone 1 (11 cases) anastomosis (34 vs 42 minutes, P = .043). CONCLUSIONS: The FET procedure with debranch-first technique is safe and feasible and resulted in low mortality and morbidity rates. Further investigation is needed to compare it with standard techniques.

Hydrodynamic and Geometric Behavior of Two Pericardial Prostheses Implanted in Small Aortic Roots.

Hydrodynamic performance of stented bioprostheses is far below that of the native valve. One of the reasons is that the internal diameter of the prosthesis is usually smaller than that of the native valve. However, other valve characteristics are also important in generating the pressure drop. We aimed to assess, in an ex vivo pulsatile mock loop, the hydrodynamic behavior of two bioprostheses, Trifecta and Mitroflow, to ascertain which geometric terms are limiting factors in hydrodynamic performance. At stroke volumes between 30 and 60 ml, Trifecta showed lower pressure drop, energy dissipation and valve resistance, and greater effective orifice area. This trend was overturned at higher stroke volumes, with Mitroflow slightly outperforming Trifecta. The geometric determinants were consistent with these results. Trifecta achieved its maximum opening area already at the lowest stroke volumes, featuring a divergent shape at the systolic peak. Mitroflow showed a complex opening pattern, featuring a convergent shape at the systolic peak for lower stroke volumes, while reaching its maximum opening area at higher stroke volumes, with a divergent shape. The two bioprostheses, although similar in design, displayed different biomechanical behaviors. The internal diameter of each bioprosthesis did not show to be strictly correlated with its hydrodynamic characteristics.

Unexpected Radiation-Induced Aortic Wall Thickening Requiring Composite Graft Technique during Off-Pump Coronary Artery Bypass Grafting.

Mediastinal radiation is commonly used to treat Hodgkin's and non-Hodgkin's lymphoma, lung and breast cancer. Cardiac complications after radiation therapy are well described, although rare. A large spectrum of injuries can occur, causing long term morbidity among survivors. We describe a case of post-actinic ascending aortic wall thickening that prevented saphenous vein proximal anastomosis and was successfully managed with aortic no-touch off-pump coronary artery bypass grafting (OPCAB), 25 years after radiation therapy for Hodgkin's lymphoma.

Aortic Root Biomechanics After Sleeve and David Sparing Techniques: A Finite Element Analysis.

BACKGROUND: Aortic root aneurysm can be treated with valve-sparing procedures. The David and Yacoub techniques have shown excellent long-term results but are technically demanding. Recently, a new and simpler procedure, the Sleeve technique, was proposed with encouraging results. We aimed to quantify the biomechanics of the initially aneurysmal aortic root (AR) after the Sleeve procedure to assess whether it induces abnormal stresses, potentially undermining its durability. METHODS: Two finite element (FE) models of the physiologic and aneurysmal AR were built, accounting for the anatomical asymmetry and the nonlinear and anisotropic mechanical properties of human AR tissues. On the aneurysmal model, the Sleeve and David techniques were simulated based on the corresponding published technical features. Aortic root biomechanics throughout 2 consecutive cardiac cycles were computed in each simulated configuration. RESULTS: Both sparing techniques restored physiologic-like kinematics of aortic valve (AV) leaflets but induced different leaflets stresses. The time course averaged over the leaflets' bellies was 35% higher in the David model than in the Sleeve model. Commissural stresses, which were equal to 153 and 318 kPa in the physiologic and aneurysmal models, respectively, became 369 and 208 kPa in the David and Sleeve models, respectively. CONCLUSIONS: No intrinsic structural problems were detected in the Sleeve model that might jeopardize the durability of the procedure. If corroborated by long-term clinical outcomes, the results obtained suggest that using this new technique could successfully simplify the surgical repair of AR aneurysms and reduce intraoperative complications.

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.

Hemodynamic comparison between Trifecta and freestyle aortic valve during exercise in patients with small aortic root.

BACKGROUND: Patients with a small aortic annulus, that is ≤ 23 mm, constitute a challenge for the surgeon, because they are at high risk of patient-prosthesis mismatch. Stentless valves provide better hemodynamic performance at rest and during exercise than stented valves, and are advocated in this group of patients. A new-generation stented valve, the Trifecta (St. Jude), has recently become available with improved hemodynamics. The aim of this study was to compare the hemodynamic performance of Freestyle (Medtronic) and Trifecta at rest and during exercise in patients with a small aortic annulus. METHODS: From September 2012 to September 2014, 22 patients with a native aortic annulus ≤ 23 mm underwent ergometric stress testing one year after aortic valve replacement with either a Trifecta (12 patients) or a Freestyle (10 patients) bioprosthesis as part of a randomized study. RESULTS: The mean gradient at rest was 6.0 ± 2.3 mmHg for Trifecta and 4.3 ± 3.5 for Freestyle (p = 0.213). The mean gradient at peak of exercise was 9.7 ± 3.4 mmHg for Trifecta and 7.4 ± 5 mmHg for Freestyle (p = 0.243). No significant differences were found between the two prostheses regarding other hemodynamic parameters: effective orifice area, velocity index, and performance indexes. CONCLUSION: Both the stented Trifecta and stentless Freestyle prostheses provide excellent hemodynamic results during physical stress in patients with a small aortic annulus. Our study confirms that Trifecta implantation results in low gradients at rest and during exercise and that the performance of Trifecta is similar to that of a stentless valve.

Hemodynamic comparison between Trifecta and Freestyle valves implanted in small aortic roots. One-year echocardiographic results from a prospective randomized study.

BACKGROUND AND AIM OF THE STUDY: Aortic valve replacement in patients with a small aortic root may be associated to high residual gradients. In such patients, both stentless valves and aortic annulus enlargement can reduce these residual gradients. Several studies have reported that Trifecta valves yield very good hemodynamic results. The aim of the present study was to compare the hemodynamic performance of Trifecta vs. Freestyle valves at one year in patients with an aortic annulus ≤ 2.3 cm. METHODS: Between September 2011 and September 2013, 40 patients with a native aortic annulus diameter ≤ 2.3 cm and average age of 81 ± 4 years, were randomized to receive either a St-Jude Trifecta stented prosthesis (20 patients) or a Medtronic Freestyle stentless prosthesis (20 patients). RESULTS: No differences between Trifecta and Freestyle were found at one year in mean gradient s: 6.1 ± 3 mmHg and 6.6 ± 3 mmHg (p = 0.796); effective ori fice area: 1.82 ± 0.3 mmHg and 1.76 ± 0.4 mmHg (p = 0.676) or regression of left ventricular mass: - 25% ± 14 vs. -19% ± 16 (p = 0.204), respectively. Only moderate patient -pro sthesis mismatch was found, which affected 3 patient s in each group. CONCLUSION: At one year both stentless and stented prostheses yielded comparable hemodynamic results. These data suggest that Trifecta implantation is a valid means of avoiding patient -prosthesis mismatch in aortic valve replacement in elderly patients with a small native aortic annulus.