How to prevent venous cannula orifice obstruction during extracorporeal circulation.

Venous cannula orifice obstruction is an underestimated problem during augmented cardiopulmonary bypass (CPB), which can potentially be reduced with redesigned, virtually wall-less cannula designs versus traditional percutaneous control venous cannulas. A bench model, allowing for simulation of the vena cava with various affluent orifices, venous collapse and a worst case scenario with regard to cannula position, was developed. Flow (Q) was measured sequentially for right atrial+hepatic+renal+iliac drainage scenarios, using a centrifugal pump and an experimental bench set-up (afterload 60 mmHg). At 1500, 2000 and 2500 RPM and atrial position, the Q values were 3.4, 6.03 and 8.01 versus 0.77*, 0.43* and 0.58* l/min: p<0.05* for wall-less and the Biomedicus® cannula, respectively. The corresponding pressure values were -15.18, -31.62 and -74.53 versus -46.0*, -119.94* and -228.13* mmHg. At the hepatic position, the Q values were 3.34, 6.67 and 9.26 versus 2.3*, 0.42* and 0.18* l/min; and the pressure values were -10.32, -20.25 and -42.83 versus -23.35*, -119.09* and -239.38* mmHg. At the renal position, the Q values were 3.43, 6.56 and 8.64 versus 2.48*, 0.41* and 0.22* l/min and the pressure values were -9.64, -20.98 and -63.41 versus -20.87 -127.68* and -239* mmHg, respectively. At the iliac position, the Q values were 3.43, 6.01 and 9.25 versus 1.62*, 0.55* and 0.58* l/min; the pressure values were -9.36, -33.57 and -44.18 versus -30.6*, -120.27* and -228* mmHg, respectivly. Our experimental evaluation demonstrates that the redesigned, virtually wall-less cannulas, allowing for direct venous drainage at practically all intra-venous orifices, outperform the commercially available control cannula, with superior flow at reduced suction levels for all scenarios tested.

Effects of different types of exercise training followed by detraining on endothelium-dependent dilation in patients with recent myocardial infarction.

BACKGROUND: In coronary artery disease, exercise training (ET) is associated with an improvement in endothelial function, but little is known about the relative effect of different types of training. The purpose of this study was to prospectively evaluate the effect of different types of ET on endothelial function in 209 patients after a first recent acute myocardial infarction. METHODS AND RESULTS: Endothelial function was evaluated before and after 4 weeks of different types of ET and after 1 month of detraining by measuring flow-mediated dilation and von Willebrand factor levels at baseline and after ET. Patients were randomized into 4 groups: group 1, aerobic ET (n=52); group 2, resistance training (n=54); group 3, resistance plus aerobic training (n=53); and group 4, no training (n=50). At baseline, flow-mediated dilation was 4.5+/-2.6% in group 1, 4.01+/-1.6% in group 2, 4.4+/-4% in group 3, and 4.3+/-2.3% in group 4 (P=NS). After ET, flow-mediated dilation increased to 9.9+/-2.5% in group 1, 10.1+/-2.6% in group 2, and 10.8+/-3% in group 3 (P<0.01 versus baseline for all groups); it also increased in group 4 but to a much lesser extent (to 5.1+/-2.5%; P<0.01 versus trained groups). The von Willebrand factor level after ET decreased by 16% (P<0.01) similarly in groups 1, 2, and 3 but remained unchanged in group 4. Detraining returned flow-mediated dilation to baseline levels (P<0.01 versus posttraining). CONCLUSIONS: In patients with recent acute myocardial infarction, ET was associated with improved endothelial function independently of the type of training, but this effect disappeared after 1 month of detraining.

Atrial assist device, a new alternative to lifelong anticoagulation?

OBJECTIVE: Atrial fibrillation is a very common heart arrhythmia, associated with a five-fold increase in the risk of embolic strokes. Treatment strategies encompass palliative drugs or surgical procedures all of which can restore sinus rhythm. Unfortunately, atria often fail to recover their mechanical function and patients therefore require lifelong anticoagulation therapy. A motorless volume displacing device (Atripump) based on artificial muscle technology, positioned on the external surface of atrium could avoid the need of oral anticoagulation and its haemorrhagic complications. An animal study was conducted in order to assess the haemodynamic effects that such a pump could provide. METHODS: Atripump is a dome-shape siliconecoated nitinol actuator sewn on the external surface of the atrium. It is driven by a pacemaker-like control unit. Five non-anticoagulated sheep were selected for this experiment. The right atrium was surgically exposed, the device sutured and connected. Haemodynamic parameters and intracardiac ultrasound (ICUS) data were recorded in each animal and under three conditions; baseline; atrial fibrillation (AF); atripump assisted AF (aaAF). RESULTS: In two animals, after 20 min of AF, small thrombi appeared in the right atrial appendix and were washed out once the pump was turned on. Assistance also enhanced atrial ejection fraction. 31% baseline; 5% during AF; 20% under aaAF. Right atrial systolic surfaces (cm2) were; 5.2 +/- 0.3 baseline; 6.2 +/- 0.1 AF; 5.4 +/- 0.3 aaAF. CONCLUSION: This compact and reliable pump seems to restore the atrial "kick" and prevents embolic events. It could avoid long-term anticoagulation therapy and open new hopes in the care of end-stage heart failure.

A simple way to decompress the left ventricle during venoarterial bypass.

OBJECTIVE: The aim of this investigation was to improve the hemodynamics during venoarterial bypass by remote decompression of the left ventricle (LV). METHODS: Venoarterial bypass was established in 5 bovine experiments (69+/-10 kg) by the transjugular insertion of a self-expanding cannula (smartcanula) with return through a carotid artery. Cardiogenic shock was simulated with ventricular fibrillation induced by an external stimulator. Left ventricular decompression was achieved by switching to transfemoral drainage of the pulmonary artery (PA) with a long self-expanding cannula. RESULTS: Initial pump flow was 4.7+/-0.9 l/min and the aortic pressure accounted for 75+/-21 mmHg. After induction of ventricular fibrillation, the pump flow dropped after 11+/-8 min to 2.5+/-0.1 l/min. Transfemoral decompression increased the pump flow to 5.6+/-0.7 l/min, while the RV pressure decreased from 27+/-9 to 3+/-5 mmHg, the PA pressure decreased from 29+/-7 to 5+/-4 mmHg, the LV pressure decreased from 29+/-6 to 7+/-2 mmHg, and the aortic pressure increased from 31+/-3 to 47+/-11 mmHg. CONCLUSIONS: Remote drainage of the pulmonary artery during venoarterial bypass allows for effective decompression of the left ventricle and provides superior hemodynamics.

[Hybrid procedures in congenital heart disease]. / Interventions hybrides et malformations cardiaques congénitales.

Increasing complexity in management of congenital heart disease imposes more frequent surgeries and interventions. Each technique has its own limitations, which could impair the anticipated result. Hybrid procedures join the advantages of cardiac surgery and interventions, creating a synergy in the management of these patients with cardiac anomalies. In our experience, hybrid procedures shorten cardiopulmonary bypass, reduce morbidity of surgery and reduce duration of stay in the intensive care unit. For some complex congenital heart diseases for which there are no ideal surgical or interventional options, hybrid procedures are becoming increasingly important in their management. Finally hybrid procedures allow surgeons and cardiologist to achieve complex procedures that could not be possible in another way.

[Hybrid treatment of aortic aneurysms]. / Les cures hybrides des lésions anévrismales.

The hybrid treatment of aortic aneurysms is indicated in patients having the ostia of supra aortic or visceral branches taken in to the aneurysm. Indeed, these lesions are not eligible for classic endovascular treatment because the existing endoprostheses cannot provide perfusion of the side branches without inducing major endoleaks. The surgical technique consists of 2 steps: firstly, a by-pass between normal aorta and the major aortic branches involved in the aneurysm is performed to guarantee the perfusion of the organs such as brain, bowel, and after endoprosthesis deployment. Secondly, the endoprosthesis is deployed using the classical technique to isolate the aneurysm. The hybrid approach provides safe and reliable treatment of complex aortic aneurysms with mortality and morbidity rate far below the classical open surgery.

[Indications, limits and future of epidural spinal cord electrical stimulation for coronary and peripheral artery disease]. / Indications, perspectives et limites de la stimulation electrique epidurale en cas d'artériopathie périphérique ou coronarienne.

The electrical stimulation of the dorsal columns of the spinal cord exerts a dual analgesic and vasodilatory effect on ischemic tissues. It is increasingly considered a valuable method to treat severe and otherwise intractable coronary and peripheral artery disease. The quality of the results depends from both a strict selection of the patients by vascular specialists and the frequency and quality of the follow-up controls. However the indications, limits, mode of action and results of spinal cord stimulation are still poorly understood. This article, based on a personal experience of 164 implantations for peripheral and coronary artery disease, aims to draw attention to this technique and to provide information on recent and future developments.

[Stents valves for percutaneous valve replacement]. / Remplacement valvulaire percutané au moyen de stent-valves--une nouvelle approche thérapeutique.

Stents have a long history in traditional valve surgery as both, porcine biological valves as well as pericardial valves are mounted on stents prior to implantation. Recently stent-mounted biological devices have been compressed up to the point, where they can be passed through a catheter. Various routes can be distinguished for implantation: open access, the trans-vascular route in antegrade or retrograde fashion, as well as direct trans-apical or trans-atrial access. Direct access has the potentialforvideo-endoscopic valve replacement. In theory, as well as in the experimental setting, valved stents have been implanted in tricuspid and caval position respectively, as well as in pulmonary, mitral and aortic locations. The largest clinical experience has been achieved in pulmonary position whereas current efforts target the aortic position.

Rupture and migration of an endovascular stent in the brachiocephalic trunk causing a vertebral steal syndrome.

Delayed stent fracture has been observed in many different arteries and may represent a risk factor for restenosis. We describe the case of a delayed rupture of an endovascular brachiocephalic trunk stent. The complete fracture allowed a fragment to migrate distally and tilt, resulting in a hemodynamic pattern similar to that of a prevertebral stenosis with complete inversion of the homolateral vertebral blood flow. The induced vertebral steal syndrome as well as the risk of cerebral embolism was corrected by an aortobrachiocephalic bypass and resection of the ruptured stent.

Chronic peritoneal effusion secondary to partial caudal vena cava obstruction following traumatic pneumothorax in a dog.

A three-year old, female Boxer Dog was treated initially with thoracocentesis for a right-sided pneumothorax. The dog was re-evaluated after three weeks because of an enlargement of the abdomen. A positive venogram revealed a ventral displacement of the caudal vena cava between the diaphragm and the heart, with a severe reduction of the diameter of the vein. An exploratory thoracotomy showed a displaced accessory lung lobe with an adhesion to the parietal pleura. Inflation of this lung lobe created a dynamic obstruction of the caudal vena cava, which resulted in ascites. Surgery offered successful treatment.

[Cell therapies in cardiology: results from the first randomized clinical trials]. / Thérapie cellulaire en cardiologie: bilan des premiers essais cliniques randomisés.

Following acute myocardial infarction, necrotic cardiac tissue is replaced by scar leading to ventricular remodeling and pump failure. Transplantation of autologous bone marrow-derived cells into the heart, early post-infarct, aims to prevent ventricular remodeling. This strategy has been evaluated in four controlled, randomized clinical trials, which provided mixed results. A transient improvement in ventricular function was observed in one trial, and a modest improvement (the duration of which remains to be determined) in an additional trial, whereas two trials showed negative results. A modest benefit of bone marrow cell transplantation was also observed in patients with chronic ischemic heart disease. Despite mixed results reported so far, cell therapy of heart disease still is in its infancy and has considerable room for improvement.

Late outcome of spinal cord stimulation for unreconstructable and limb-threatening lower limb ischemia.

OBJECTIVES: To determine whether the initial benefits of spinal cord stimulation (SCS) treatment for critical limb ischemia (CLI) persist over years. DESIGN: Analysis of data prospectively collected for every CLI patient receiving permanent SCS. Follow-up range 12 to 98 months (mean 46+/-23, median 50 months). POPULATION: 87 patients (28% stage III, 72%stage IV) with unreconstructable CLI due (83%) or not (17%) to atherosclerosis and with an initial sitting/supine transcutaneous pO2 gradient >15 mmHg. METHODS: Assessment of actuarial patient survival (PS), limb salvage (LS) and amputation-free patient survival (AFPS). Analysis of the impact of 15 risk factors on long-term outcomes using the Fischer's exact test for categorical variables and the t test for continuous variables. RESULTS: Follow-up was complete for patient and limb survival. A single non-atherosclerotic patient died during follow-up. Among atherosclerotic patients PS decreased from 88% at 1y, to 76% at 3y, 64% at 5y and 57% at 7y. LS reached 84% at 1y, 78% at 2y, 75% at 3y and remained stable thereafter. Diabetes was found to affect LS (p<0.05) and heart disease to reduce PS (p<0.01). AFPS was reduced in heart patients (p<0.01), diabetics (p<0.05) and in patients with previous stroke (p<0.05). CONCLUSIONS: In CLI patients the beneficial effects of SCS persist far beyond the first year of treatment and major amputation becomes infrequent after the second year.

New bench test for venous cannula performance assessment.

Cannula design is of prime importance for venous drainage during cardiopulmonary bypass (CPB). To evaluate cannulas intended for CPB, an in vitro circuit was set up with silicone tubing between the test cannula encased in a movable preload reservoir and another static reservoir. The pressure-drop (DeltaP) value (P-drainage - P-preload) was measured using Millar pressure transducers. Flow rate (Q) was measured using an ultrasound flowmeter. Data display and data recording were controlled using a LabView application, custom made particularly for our experiments. Our results demonstrated that DeltaP, Q, and cannula resistance (DeltaP/Q) values were significantly decreased when the cannula diameter was increased for Smart and Medtronic cannulas. Smartcanula showed 36% and 43% less resistance compared to Medtronic venous and Medtronic femoral cannulas, respectively. The cannula shape (straight- or curved-tips) did not affect the DLP cannula resistance. Out of five cannulas tested, the Smartcanula outperforms the other commercially available cannulas. The mean (DeltaP/Q) values were 3.3 +/- 0.08, 4.07 +/- 0.08, 5.58 +/- 0.10, 5.74 +/- 0.15, and 6.45 +/- 0.15 for Smart, Medtronic, Edwards, Sarns, and Gambro cannulas, respectively (two-way ANOVA, p < 0.0001). In conclusion, the present assay allows discrimination between different forms of cannula with high or low lumen resistance.

Using computational fluid dynamics to evaluate a novel venous cannula (Smart canula) for use in cardiopulmonary bypass operating procedures.

Peripheral access cardiopulmonary bypass (CPB) is initiated with percutaneous cannulae (CTRL) and venous drainage is often impeded due to smaller vessel and cannula size. A new cannula (Smartcanula, SC) was developed which can change shape in situ and, therefore, may improve venous drainage. Its performance was evaluated using a 2-D computational fluid dynamics (CFD) model. The Navier-Stokes equations could be simplified due to the fact that we use a steady state and a 2-dimensional system while the equation of continuity (p constant) was also simplified. We compared the results of the SC to the CTRL using CFDRC (Version 6.6, CFDRC research corporation, Huntsville, USA) at two preloads (300 and 700 Pa). The SC's mass flow rate outperformed the CTRL by 12.1% and 12.2% at a pressures of 300 and 700 Pa, respectively. At 700 Pa, a pressure gradient of 50% was measured for the CTRL and 11% for the SC. The mean velocity at the 700 Pa for the CTRL was 1.0 m.s(-1) at exit while the SC showed an exit velocity of 1.3 m.s(-1). Shear rates inside the cannulae were similar between the two cannulae. In conclusion, the prototype shows greater mass flow rates compared to the classic cannula; thus, it is more efficient. This is also advocated by a better pressure gradient and higher average velocities. By reducing cannula-tip surface area or increasing hole surface area, greater flow rates are achieved.

Intra vascular ultra sound: one more tool to diagnose aorto-duodenal fistula.

The incidence of aorto-enteric fistula in the first 5 years after abdominal aortic replacement ranges from 0.3 to 2%. We present a clinical case in which all conventional diagnostic tools failed to demonstrate the aorto-enteric fistula. A 73 year-old male suffering intermittent episodes of melena without signs and symptoms of infection was repeatedly admitted at our institution. All conventional diagnostic tools failed to show the bleeding source. Precise diagnosis was obtained using intra vascular ultrasound (IVUS). IVUS allowed prompt diagnosis of the aorto-duodenal fistula and opened the way to its endovascular treatment.

[Transposition of the great arteries: long-term follow-up]. / Transposition des gros vaisseaux: suivi a long-terme.

The management of transposition of the great arteries has changed importantly over the last decades. New techniques are employed for the diagnosis and surgical intervention has improved. This has lead to an increasing number of long-term survivors, who require specialised and focussed follow-up, depending on their type of surgical repair Mustard/Senning of arterial Switch. The long-term problems vary for each type of repair and require a specific approach, pharmacotherapy, catheter intervention or surgery. These complex sequellae implicate that transposition patients are never completely cured and probably will have a limited life span.

Gene transfer of RANTES and MCP-1 chemokine antagonists prolongs cardiac allograft survival.

Vascularized organ allografts are rapidly destroyed by host immune cells that are recruited along chemokine gradients. Among chemokines, Regulated on Activation, Normal T-cell Expressed and Secreted (RANTES) CC chemokine ligand (CCL5) and monocyte chemoattractant protein (MCP)-1 (CCL2) are upregulated in rejecting cardiac allografts. To antagonize these chemokines, we constructed adenoviral vectors expressing NH(2)-terminal deletion (8ND) mutants of the respective genes. Using the F344-to-LEW rat model, intragraft gene transfer of chemokine analogs prolonged cardiac allograft survival from 10.1+/-0.7 and 10.4+/-0.7 days using non-coding adenovirus and vehicle alone, respectively, to 17.0+/-0.7 days for 8ND-RANTES (P<0.001) and 14.2+/-0.8 days for 8ND-MCP-1 (P<0.01). 8ND-RANTES reduced graft infiltration by monocytes/macrophages, cluster of differentiation (CD) 8alpha(+) and T-cell receptor alphabeta(+) cells, while 8ND-MCP-1 reduced monocytes/macrophages. In mixed leukocyte reactions in vitro, proliferation of host lymphocytes from regional lymph nodes in response to donor splenocytes was unaffected by 8ND-RANTES gene transfer. Using a two-gene approach, the contribution of 8ND-MCP-1 was negligible, consistent with available evidence that 8ND-RANTES inhibits both RANTES and MCP-1 activities. 8ND-RANTES gene transfer and a short course of low-dose cyclosporine A synergistically prolonged graft survival to 37.8+/-5.5 vs 15.4+/-0.5 days with cyclosporine alone (P<0.001). These results suggest a role for anti-chemokine gene therapy as an adjuvant therapy in heart transplantation.

Ex vivo evaluation of a new extracorporeal lung assist device: NovaLung membrane oxygenator.

When lung function is compromised,alternative devices need to be deployed in order to maintain blood oxygenation. A new device, NovaLung, has been designed for acute lung failure. We went about evaluating its gas exchange capability. Three calves (79.5 +/- 7.8 kg) were connected to the NovaLung System with a priming volume of 240 mL, gas exchange surface area of 1.3 m2 and exhibiting a biologically coated surface. A standard battery of blood samples were taken before implantation and over a six hour period. Hematocrit remained stable ranging from 27 +/- 4% (baseline) to 29 +/- 5% (6 hrs). Platelets were preserved ranging from 882 +/- 27.4 U/L (baseline) to 734 +/- 147 (6 hrs). LDH remained stable at 719 +/- 85 U/L (baseline) vs 686 +/- 190 U/L (6 hrs) and the pressure drop was maintained below 20 mmHg. Minimal hemolysis was observed. Oxygen transfer peaked at two hours acute extracorporeal lung support (ECLS)with a mean value of 130 +/- 50 ml/min. In conclusion, the device is easy to use,provides adequate O2 and CO2 transfer for partial lung support in an acute setting. Shows minimal signs of hemolysis and platelets levels are maintained throughout the six hour ECLS period.

[Surgical options for terminal heart failure]. / Options chirurgicates pour l'insuffisance cardiaque terminale.

Terminal heart failure can be the cause or the result of major dysfunctions of the organisms. Although, the outcome of the natural history is the same in both situations, it is of prime importance to differentiate the two, as only heart failure as the primary cause allows for successful mechanical circulatory support as bridge to transplantation or towards recovery. Various objective parameters allow for the establishment of the diagnosis of terminal heart failure despite optimal medical treatment. A cardiac index <2.0 l/min, and a mixed venous oxygen saturation <60%, in combination with progressive renal failure, should trigger a diagnostic work-up in order to identify cardiac defects that can be corrected or to list the patient for transplantation with/without mechanical circulatory support.