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Objective: To evaluate the feasibility of the off-bypass implantation of a self-expandable valved stent of large size in pulmonary position. Materials and methods: A glutaraldehyde preserved valved bovine jugular xenograft with internal diameter=22 mm, mounted in two rings of nitinol ‘Z' stent, expandable from 7 to 24 mm of internal diameter, was acutely evaluated in 6 adult pigs, mean body weight 55.6 kg (range 47-67 kg). Through a stent-graft delivery system (24 French) the self expandable valved stent was implanted off-bypass in pulmonary valve position by trans-ventricular approach through median sternotomy. Results: The mean diameter of the main pulmonary artery measured was 21.7±1.6 mm. The mean length of the self expandable valved stent was 23.1±0.7 mm, the mean internal diameter 21.6±0.7 mm and the mean external diameter 26.3±0.7 mm. The mean peak pressure gradient recorded across the valve was 6.33±2.8 mmHg (range 4.5-9.6 mmHg) at Doppler echocardiography, and 4.5±3.1 mmHg (range 0-7 mmHg) at invasive measurement, with a pulmonary blood flow of 3.03±0.05 l/min. Intra-vascular ultrasound showed complete opening and closure of the valve (mean area reduction from 315.08±54.13 to 0 mm2). Conclusions: (a) Off-bypass implantation of self-expandable valved stent is feasible in pulmonary position; (b) off-bypass surgical approach allows for valved stent implantation of adult size with adequate hemodynamic functioning; and (c) intra-vascular ultrasound makes implantation and evaluation easy and reproducible

Objective: Patients with irreversible pulmonary vascular obstructive disease caused by pulmonary hypertension due to congenital heart defects are considered either inoperable or only candidates to lung transplantation. This study evaluated an experimental model of surgically induced unilateral pulmonary hypertension. Methods: In eight pigs, 2-months-old, the left pulmonary artery was divided at the origin and end-to-side anastomosed to the descending thoracic aorta through a left thoracotomy. In this way, increased pulmonary blood flow in the right lung and systemic perfusion pressure and oxygenation in the left lung were obtained. After an interval of 6-12 weeks the animals underwent cardiac catheterization and were then sacrificed. Histological examination was done on both the lungs. Results: The mean left-to-right shunt through the left pulmonary artery diminished from 58.9±9.6% at the end of the procedure to 4.5±1.5% at the latest hemodynamic evaluation (P<0.01). Pressures and saturations remained identical in aorta and left pulmonary artery, without reduction (NS) with FiO2=1.0 ventilation; in the right pulmonary artery there was a mild elevation of the pressures, but still responsive (P<0.05) to FiO2=1.0 ventilation. Lung histology showed normal right pulmonary arteries, but irreversible vascular lesions like intimal fibrosis, medial hypertrophy, vascular occlusions, plexiform and dilatation lesions in all the left lungs. Conclusions: The lung exposed to systemic pressure and oxygenation develops irreversible vascular lesions typical of pulmonary vascular obstructive disease. The lung exposed to increased flow shows only mild elevation of the arterial pressure, remains responsive to oxygen vasodilatation, and displays normal histology

OBJECTIVES To learn upon incidence, underlying mechanisms and effectiveness of treatment strategies in patients with central airway and pulmonary parenchymal aorto-bronchial fistulation after thoracic endovascular aortic repair (TEVAR). METHODS Analysis of an international multicentre registry (European Registry of Endovascular Aortic Repair Complications) between 2001 and 2012 with a total caseload of 4680 TEVAR procedures (14 centres). RESULTS Twenty-six patients with a median age of 70 years (interquartile range: 60-77) (35% female) were identified. The incidence of either central airway (aorto-bronchial) or pulmonary parenchymal (aorto-pulmonary) fistulation (ABPF) in the entire cohort after TEVAR in the study period was 0.56% (central airway 58%, peripheral parenchymal 42%). Atherosclerotic aneurysm formation was the leading indication for TEVAR in 15 patients (58%). The incidence of primary endoleaks after initial TEVAR was n = 10 (38%), of these 80% were either type I or type III endoleaks. Fourteen patients (54%) developed central left bronchial tree lesions, 11 patients (42%) pulmonary parenchymal lesions and 1 patient (4%) developed a tracheal lesion. The recognized mechanism of ABPF was external compression of the bronchial tree in 13 patients (50%), the majority being due to endoleak formation, further ischaemia due to extensive coverage of bronchial feeding arteries in 3 patients (12%). Inflammation and graft erosion accounted for 4 patients (30%) each. Cumulative survival during the entire study period was 39%. Among deaths, 71% were attributed to ABPF. There was no difference in survival in patients having either central airway or pulmonary parenchymal ABPF (33 vs 45%, log-rank P = 0.55). Survival with a radical surgical approach was significantly better when compared with any other treatment strategy in terms of overall survival (63 vs 32% and 63 vs 21% at 1 and 2 years, respectively), as well as in terms of fistula-related survival (63 vs 43% and 63

OBJECTIVES During open heart surgery, so-called atrial chatter, a phenomenon due to right atria and/or caval collapse, is frequently observed. Collapse of the cava axis during cardiopulmonary bypass (CPB) limits venous drainage and may result downstream in reduced pump flow on (lack of volume) and upstream in increased after-load (stagnation), which in turn may both result in reduced or even inadequate end-organ perfusion. The goal of this study was to reproduce venous collapse in the flow bench. METHODS In accordance with literature for venous anatomy, a caval tree system is designed (polyethylene, thickness 0.061 mm), which receives venous inflow from nine afferent veins. With water as medium and a preload of 4.4 mmHg, the system has an outflow of 4500 ml/min (Scenario A). After the insertion of a percutaneous venous cannula (23-Fr), the venous model is continuously served by the afferent branches in a venous test bench and venous drainage is augmented with a centrifugal pump (Scenario B). RESULTS With gravity drainage (siphon: A), spontaneously reversible atrial chatter can be generated in reproducible fashion. Slight reduction in the outflow diameter allows for generation of continuous flow. With augmentation (B), irreversible collapse of the artificial vena cava occurs in reproducible fashion at a given pump speed of 2300 ± 50 RPM and a pump inlet pressure of −112 mmHg. Furthermore, bubbles form at the cannula tip despite the fact that the entire system is immersed in water and air from the environment cannot enter the system. This phenomenon is also known as cavitation and should be avoided because of local damage of both formed blood elements and endothelium, as well embolization. CONCLUSIONS This caval model provides a realistic picture for the limitations of flow due to spontaneously reversible atrial chatter vs irreversible venous collapse for a given negative pressure during CPB. Temporary interruption of negative pressure in the venous line can allow for

Objective: Off-pump trans left ventricular approach provides more precise deployment of stented aortic valve of any size with respect to the endovascular replacement. One of the key steps of this procedure is the ventricle repair after catheter withdrawing. We designed an animal study to compare the consistency of a sutureless repair of the left ventricle access using nitinol occluder with and without pericardial cuff on the ventricular side. Methods: Material description: The Amplatz-nitinol occluder consists of two square heads squeezing ventricle wall in between them, sealing the defect. To improve its sealing property, a pericardial patch was sutured to the ventricular head of the occluder. Animal study setup: In adult pigs, a 30F sheath was inserted into the epigastric area through the cardiac apex, up to the left ventricle, simulating the approach for off-pump aortic valve replacement. The sheath was then removed and the ventricle closed with standard occluder in half of the animals, and cuffed occluder in the other half. Animals were followed-up for 3h, collecting haemodynamics data and pericardial bleeding. Results: Device was successfully deployed in 12 animals in less than 1min. In the group where the standard occluder was used, bleeding during the deployment was 80±20ml and after the deployment was 800±20ml over 3h. In the group where the cuffed occluder was used, bleeding during the deployment was 85±20ml and after the deployment was 100±5ml over 3h. In the cuffed group, bleeding was significantly lower than the standard group, p-value being ≪0.001. Conclusions: The occluder is easy to use and the pericardial cuff dramatically increases its efficacy as demonstrated by a significant reduction of blood loss. The cuffed occluder opens the way for endoscopic, off-pump, transventricular aortic valve replacement

Objective: The aim of this study was to investigate the feasibility of transventricular-transseptal approach (TVSA) for extrapleural trans-catheter aortic valved stent implantation via a subxyphoidian access. Methods: In five porcine experiments (52.3±10.9kg) the right ventricle was exposed via subxyphoidian access. Under the guidance of intracardiac echocardiography (ICE) and fluoroscopy, the transseptal access from right ventricle to left ventricle was created progressively by puncture and dilation with dilators (8F-26F). Valved stents built in-house from commercial tanned pericardium and self-expandable Nitinol stents were loaded into a cartridge. A delivery sheath was then introduced from the right ventricle into the left ventricle and then into the ascending aorta. The cartridge was connected and the valved stent was deployed in the aortic position. Then, the ventricular septal access was sealed with an Amplatzer septal occluder device and the right ventricular access was closed by tying prepared purse-string suture directly. Thirty minutes after the whole procedure, the animals were sacrificed for macroscopic evaluation of the position of valved stent and septal closure device. Result: Procedural success of TVSA was 100% at the first attempt. Mean procedure time was 49±4min. Progressive dilatation of the transseptal access resulted in a measurable ventricular septal defect (VSD) after dilator sizes 18F and more. All valved stents were delivered at the target site over the native aortic valve with good acute valve function and no paravalvular leaks. During the procedure, premature beats (5/5) and supraventriclar tachycardias (5/5) were observed, but no atrial-ventricular block (0/5) occurred. Heart rate before (after) was 90±3 beatsmin−1 (100±2 beatsmin−1: p≪0.05), whereas blood pressure was 60±1mmHg (55±2mmHg (p≪0.05)). Total blood loss was 280±10ml. The Amplatzer septal occluder devices were fully deployed and the ventricular septal accesses were sealed succe

The advent of stents has profoundly changed percutaneous transluminal coronary angioplasty (PTCA), peripheral transluminal artery angioplasty (PTA), and treatment strategies of numerous other problems. Similar developments can be observed for stent applications in peripheral vascular lesions, cerebro-vascular disease, and many other fields. With the advent of covered stent-grafts, aneurysm surgery, has been put up for competitive treatment approaches. Such new approaches are perceived as less invasive, and draw significant attention. Endovsacular aneurysm repair (EVAR) is here to stay. In addition new developments are coming in many ways and stent derived devices can by now be found everywhere in the cardio-vascular system. This includes stenosed vessels, aneurysmal vessels, diseased valves, all sorts of congenital heart defects, and even cardiopulmonary bypass. The key technologies and know-how for EVAR are available or can be made available in most cardio-vascular surgical units. Special interest in this field (clinical and/or experimental) can enhance recruitment of patients. The opposite is also true

OBJECTIVES Residual mitral regurgitation after valve repair worsens patients' clinical outcome. Postimplant adjustable mitral rings potentially address this issue, allowing the reshaping of the annulus on the beating heart under echocardiography control. We developed an original mitral ring allowing valve geometry remodelling after the implantation and designed an animal study to assess device effectiveness in correcting residual mitral regurgitation. METHODS The device consists of two concentric rings: one internal and flexible, sutured to the mitral annulus and a second external and rigid. A third conic element slides between the two rings, modifying the shape of the flexible ring. This sliding element is remotely activated with a rotating tool. Animal model: in adult swine, under cardio pulmonary bypass and cardiac arrest, we shortened the primary chordae of P2 segment to reproduce Type III regurgitation and implanted the active ring. We used intracardiac ultrasound to assess mitral regurgitation and the efficacy of the active ring to correct it. RESULTS Severe mitral regurgitation (3+ and 4+) was induced in eight animals, 54 ± 6 kg in weight. Vena contracta width decreased from 0.8 ± 0.2 to 0.1 cm; proximal isovelocity surface area radius decreased from 0.8 ± 0.2 to 0.1 cm and effective regurgitant orifice area decreased from 0.50 ± 0.1 to 0.1 ± 0.1 cm2. Six animals had a reversal of systolic pulmonary flow that normalized following the activation of the device. All corrections were reversible. CONCLUSIONS Postimplant adjustable mitral ring corrects severe mitral regurgitation through the reversible modification of the annulus geometry on the beating heart. It addresses the frequent and morbid issue of recurrent mitral valve regurgitation

Background: Half of the patients with end-stage heart failure suffer from persistent atrial fibrillation (AF). Atrial kick (AK) accounts for 10-15% of the ejection fraction. A device restoring AK should significantly improve cardiac output (CO) and possibly delay ventricular assist device (VAD) implantation. This study has been designed to assess the mechanical effects of a motorless pump on the right chambers of the heart in an animal model. Methods: Atripump is a dome-shaped biometal actuator electrically driven by a pacemaker-like control unit. In eight sheep, the device was sutured onto the right atrium (RA). AF was simulated with rapid atrial pacing. RA ejection fraction (EF) was assessed with intracardiac ultrasound (ICUS) in baseline, AF and assisted-AF status. In two animals, the pump was left in place for 4 weeks and then explanted. Histology examination was carried out. The mean values for single measurement per animal with ±SD were analysed. Results: The contraction rate of the device was 60 per min. RA EF was 41% in baseline, 7% in AF and 21% in assisted-AF conditions. CO was 7±0.5lmin−1 in baseline, 6.2±0.5lmin−1 in AF and 6.7±0.5lmin−1 in assisted-AF status (p≪0.01). Histology of the atrium in the chronic group showed chronic tissue inflammation and no sign of tissue necrosis. Conclusions: The artificial muscle restores the AK and improves CO. In patients with end-stage cardiac failure and permanent AF, if implanted on both sides, it would improve CO and possibly delay or even avoid complex surgical treatment such as VAD implantation

Objective: An animal model has been designed to assess the feasibility of off-pump mitral valve replacement using valved stents. Methods: Glutaraldehyde-preserved homograft was sutured inside a prosthetic tube (Dacron). Then, two self-expandable nitinol Z-stents were sutured on the external surface of the prosthesis in such a way to create two self-expanding crowns for fixation. In adult pigs and under general anesthesia, the left atrium was exposed through a left thoracotomy and atrio-ventricular roadmapping was performed with intravascular ultrasound (IVUS) and fluoroscopy. The double-crowned valved stents were loaded into a delivery sheath. The sheath was then introduced into the left atrium and the valved stents was deployed in mitral position in such a way that the part in between the two stents was at the level of the mitral annulus. Intracardiac Unltrasound (ICUS) was used to assess the valve function. Hemodynamic parameters were gathered as well. Animal survived for no more than 3h after the valve deployment and gross anatomy examination of the left heart was carried out. Results: The mean height of the valved stents was 29.4±0.2mm, with an internal diameter of 20.4±1.0mm, and an external diameter of 25.5±0.8mm. The procedure was successfully carried out in eight animals. In vivo evaluation showed a native mitral annulus diameter of 24.9±0.6mm, and a mean mitral valve area of 421.4±17.5mm2. ICUS showed a mild mitral regurgitation in three out of eight animals. Mean pressure gradient across the valved stents was 2.6±3.1mmHg. Mean pressure gradient across the left ventricular outflow tract (LVOT) was 6.6±5.2mmHg. The mean survival time was 97.5±56.3min (survival time range was 40-180min). One animal died due to the occlusion of the LVOT because of valved stents displacement. Postmortem evaluation confirmed correct positioning of the valved stent in the mitral position in seven out of eight animals. No atrial or ventricular lesions due to the valved stents were

Objective: Adjustment of pulmonary blood flow is difficult in pulmonary artery banding for complex congenital heart defects. A new wireless, battery free, telemetrically controlled, implantable device (FloWatch®, EndoArt, S.A., Lausanne, Switzerland) allowing for progressive occlusion/reopening of the device through a remote control at the wanted percentage of occlusion (adjustable pulmonary artery banding) underwent experimental evaluation. Methods: Eleven mini-pigs underwent FloWatch® implantation around the main pulmonary artery through left thoracotomy. The first group (n=4), mean age 18.2±0.1 weeks, mean body weight 12.0±0.1 kg, underwent FloWatch® implantation as device tolerance test. The second group (n=7), mean age 8.6±3.4 weeks, mean body weight 5.1±1.5 kg, underwent functional evaluation: at implantation, 1, 3, 5, 8 and 10 weeks after implantation, the device was progressively occluded and reopened, with Doppler evaluation of the developed pressure gradient. Results: The four mini-pigs of first group were sacrificed at mean age of 42.3±0.1 weeks, mean body weight 25.1±3.2 kg (mean interval of 24 weeks after implantation); the device was still functioning and histology revealed almost normal morphology of the pulmonary artery. In all seven mini-pigs of second group the possibility of narrowing/releasing the pulmonary artery was confirmed at implantation and during follow-up: at last control their mean age was 20.5±2.8 weeks and the body weight 12.7±3.7 kg. Conclusions: Complete adjustment of pulmonary blood flow is now possible with an implantable device allowing for pulmonary artery banding with early and late telemetric flow control

Objective: The aim of this study is to create a standard test to approve the efficacy of a surgical sealant. An industrial test, the bulge-and-blister test, which is very convenient for measuring adhesion energy, is applied to the surgical field to quantify adhesion of bioadhesives. Methods: Samples were composed of two circular layers of equine pericardium glued by the surgical sealant studied. The sample was fixed to a support with an industrial glue. The support and the bottom layer were perforated in the centre to allow injection of pressurised water. Water was progressively introduced through the hole in the support and the bottom layer to create a blister with constant radius, increasing height and internal pressure during this first step. At a critical pressure, delamination started, the radius and height of the blister increased and the pressure decreased. At this point, the adhesion energy could be determined. The experimental parameters were measured with a pressure sensor and an optical profilometry device for deflection. Results: Adhesion testing was carried out in eight paired equine pericardium samples bonded with a Dermabond® cyanoacrylate glue. The average value of the practical adhesion energy is 2.3Jm−2 with a standard deviation of 1.5Jm−2. Conclusion: Application of the bulge-and-blister test to the surgical field was achieved and allowed a quantification of adhesion of a surgical glue. Such information is essential to compare the different surgical glues presently available. The study of the impact of bonding conditions such as pressure, hygrometry or setting conditions will provide a better understanding of the characteristics of adhesion in the surgical field

Objectives: We reviewed our surgery registry, to identify predictive risk factors for operative results, and to analyse the long-term survival outcome in octogenarians operated for primary isolated aortic valve replacement (AVR). Methods: A total of 124 consecutive octogenarians underwent open AVR from January 1990 to December 2005. Combined procedures and redo surgery were excluded. Selected variables were studied as risk factors for hospital mortality and early neurological events. A follow-up (FU; mean FU time: 77 months) was obtained (90% complete), and Kaplan-Meier plots were used to determine survival rates. Results: The mean age was 82±2.2 (range: 80-90 years; 63% females). Of the group, four patients (3%) required urgent procedures, 10 (8%) had a previous myocardial infarction, six (5%) had a previous coronary angioplasty and stenting, 13 patients (10%) suffered from angina and 59 (48%) were in the New York Heart Association (NYHA) class III-IV. We identified 114 (92%) degenerative stenosis, six (5%) post-rheumatic stenosis and four (3%) active endocarditis. The predicted mortality calculated by logistic European System for Cardiac Operative Risk Evaluation (EuroSCORE) was 12.6±5.7%, and the observed hospital mortality was 5.6%. Causes of death included severe cardiac failure (four patients), multi-organ failure (two) and sepsis (one). Complications were transitory neurological events in three patients (2%), short-term haemodialysis in three (2%), atrial fibrillation in 60 (48%) and six patients were re-operated for bleeding. Atrio-ventricular block, myocardial infarction or permanent stroke was not detected. The age at surgery and the postoperative renal failure were predictors for hospital mortality (p value ≪0.05), whereas we did not find predictors for neurological events. The mean FU time was 77 months (6.5 years) and the mean age of surviving patients was 87±4 years (81-95 years). The actuarial survival estimates at 5 and 10 years were 88% and 50%, res

Background: Recently, a compact cardiopulmonary support (CPS) system designed for quick set-up for example, during emergency cannulation, has been introduced. Traditional rectilinear percutaneous cannulas are standard for remote vascular access with the original design. The present study was designed to assess the potential of performance increase by the introduction of next-generation, self-expanding venous cannulas, which can take advantage of the luminal width of the venous vasculature despite a relatively small access orifice. Methods: Veno-arterial bypass was established in three bovine experiments (69 ± 10 kg). The Lifebridge® (Lifebridge GmbH, Munich, Germany) system was connected to the right atrium in a trans-jugular fashion with various venous cannulas; and the oxygenated blood was returned through the carotid artery with a 17 F percutaneous cannula. Two different venous cannulas were studied, and the correlation between the centrifugal pump speed (1500-3900 RPM), flow and the required negative pressure on the venous side was established: (A) Biomedicus 19 F (Medtronic, Tolochenaz, Switzerland); (B) Smart canula 18 F/36 F (Smartcanula LLC, Lausanne, Switzerland). Results: At 1500 RPM, the blood flow was 0.44 ± 0.26 l min−1 for the 19 F rectilinear cannula versus 0.73 ± 0.34 l min−1 for the 18/36 F self-expanding cannula. At 2500 RPM the blood flow was 1.63 ± 0.62 l min−1 for the 19 F rectilinear cannula versus 2.13 ± 0.34 l min−1 for the 18/36 F self-expanding cannula. At 3500 RPM, the blood flow was 2.78 ± 0.47 l min−1 for the 19 F rectilinear cannula versus 3.64 ± 0.39 l min−1 for the 18/36 F self-expanding cannula (p ≪ 0.01 for 18/36 F vs 19 F). At 1500 RPM, the venous line pressure was 18 ± 8 mmHg for the 19 F rectilinear cannula versus 19 ± 5 mmHg for the 18/36 F self-expanding cannula. At 2500 RPM the venous line pressure accounted for −22 ± 32 mmHg for the 19 F rectilinear cannula versus 2 ± 5 mmHg for the 18/36 F self-expanding cannula. At 3500 RPM

OBJECTIVES: To learn upon incidence, underlying mechanisms and effectiveness of treatment strategies in patients with central airway and pulmonary parenchymal aorto-bronchial fistulation after thoracic endovascular aortic repair (TEVAR). METHODS: Analysis of an international multicentre registry (European Registry of Endovascular Aortic Repair Complications) between 2001 and 2012 with a total caseload of 4680 TEVAR procedures (14 centres). RESULTS: Twenty-six patients with a median age of 70 years (interquartile range: 60-77) (35% female) were identified. The incidence of either central airway (aorto-bronchial) or pulmonary parenchymal (aorto-pulmonary) fistulation (ABPF) in the entire cohort after TEVAR in the study period was 0.56% (central airway 58%, peripheral parenchymal 42%). Atherosclerotic aneurysm formation was the leading indication for TEVAR in 15 patients (58%). The incidence of primary endoleaks after initial TEVAR was n = 10 (38%), of these 80% were either type I or type III endoleaks. Fourteen patients (54%) developed central left bronchial tree lesions, 11 patients (42%) pulmonary parenchymal lesions and 1 patient (4%) developed a tracheal lesion. The recognized mechanism of ABPF was external compression of the bronchial tree in 13 patients (50%), the majority being due to endoleak formation, further ischaemia due to extensive coverage of bronchial feeding arteries in 3 patients (12%). Inflammation and graft erosion accounted for 4 patients (30%) each. Cumulative survival during the entire study period was 39%. Among deaths, 71% were attributed to ABPF. There was no difference in survival in patients having either central airway or pulmonary parenchymal ABPF (33 vs 45%, log-rank P = 0.55). Survival with a radical surgical approach was significantly better when compared with any other treatment strategy in terms of overall survival (63 vs 32% and 63 vs 21% at 1 and 2 years, respectively), as well as in terms of fistula-related survival (63 vs 43% and

To test the hypothesis that simultaneous closure of at least 2 independent vascular territories supplying the spinal cord and/or prolonged hypotension may be associated with symptomatic spinal cord ischemia (SCI) after thoracic endovascular aortic repair (TEVAR).