Clinical outcome of a simplified technique for aortic valve replacement with stentless bioprostheses.

BACKGROUND AND AIM OF THE STUDY: Aortic stentless bioprostheses provide good clinical and hemodynamic results, but may be difficult to implant. Their use is also contraindicated in the presence of a severely calcified aortic root. The study aim was to assess the mid-term results of a simplified implant technique of the Sorin Pericarbon Freedom stentless bioprosthesis (SPF), that allows its use in the presence of severe aortic root calcification. METHODS: Between 2001 and 2007, a total of 51 patients underwent aortic valve replacement (AVR) with the SPF, using a new technique which consisted of standard annular fixation and the fixation of each strut with a single 'U' stitch. The perioperative characteristics, early and late mortality and occurrence of valve-related events were evaluated. The overall mean cross-clamp and cardiopulmonary bypass times were 91.5 +/- 30.2 and 125.3 +/- 44.9 min, respectively, and 77.8 +/- 17.7 and 105.6 +/- 22.8 min, respectively, for AVR (these times were comparable to those required in patients receiving stented valve bioprostheses). The mean follow up period was 40.5 months (range: 3-75 months), and was 100% complete. RESULTS: Hospital mortality was 4% and survival 76.5 +/- 14.5% at six years. Late deaths occurred in eight patients; in four cases this was valve-related (1.9%/patient-year). Freedom from valve-related death and reoperation was 91 +/- 9% and 98 +/- 2% respectively, at six years. The mean transprosthetic gradients were 12.0 +/- 3.4, 9.9 +/- 2.6, 8.7 +/- 4.2, 5.2 +/- 3.9, 4.5 +/- 3.0 and 3.2 +/- 2.7 mmHg for the 19, 21, 23, 25, 27 and 29 mm valve sizes, respectively. No valvular or paravalvular regurgitation was recorded. CONCLUSION: This new implantation technique for the aortic SPF stentless bioprosthesis is simple, effective and versatile, and showed good early results. It may be applicable to other stentless bioprostheses, and also be particularly useful in patients with small aortic annulus and in those with a calcified aortic root.

Preassembled stentless valved-conduit for the replacement of the ascending aorta and aortic root.

Here we report the early clinical results of a new preassembled stentless valved-conduit incorporating artificial sinuses of Valsalva (BioValsalva). This new composite conduit incorporates a stentless porcine aortic valve (Elan, Vascutek Terumo, UK) suspended within a triple-layered vascular conduit (Triplex, Vascutek Terumo, UK) constructed with sinuses of Valsalva. Between December 2006 and January 2008, 17 patients with the mean age of 65 years underwent aortic valve, root and ascending aorta replacement with the BioValsalva valved-conduit. There was no perioperative mortality. There were no myocardial infarctions, cardiac failure or cerebrovascular events. Mean cardiopulmonary bypass time was 156+/-56 min and ischemic time was 112+/-33 min. Eight patients required deep hypothermic circulatory arrest for additional distal ascending aorta replacement. Mean mediastinal drainage was 499+/-262 ml. Postoperative transthoracic echocardiography and CT-scans of the aorta in all patients before discharge demonstrated well-functioning prosthetic aortic valves with small residual mean gradients, no regurgitation, and the presence of sinuses of Valsalva. In conclusion, the novel prefabricated, composite stentless valved-conduit BioValsalva possesses excellent hemodynamic performance and can be implanted with low morbidity. In addition, the conduit material has good hemostatic properties which reduced bleeding, and is easy to implant with a variety of surgical techniques.

Replacement of the ascending aorta, aortic root, and valve with a novel stentless valved conduit.

PURPOSE: Biologic valved-conduit grafts avoid the need for anticoagulation and can exploit the excellent hemodynamic performance of stentless valves. Incorporation of sinuses of Valsalva into the neoaortic root can improve the function of the stentless valves. DESCRIPTION: Here we present a novel prefabricated stentless valved conduit incorporating sinuses of Valsalva and describe the technique of implantation. The BioValsalva (Vascutek Terumo, Renfrewshire, Scotland) valved conduit incorporates a stentless porcine aortic valve (Elan; Vascutek Terumo) suspended within a triple-layered vascular conduit (Triplex; Vascutek Terumo) constructed with sinuses of Valsalva. EVALUATION: The BioValsalva valved conduit was used in 12 patients with aortic regurgitation due to annuloaortic ectasia unsuitable for aortic valve repair and concomitant ascending aorta aneurysm, with no deaths and excellent functioned result. CONCLUSIONS: The prefabricated, composite, stentless valved conduit is composed of material that is hemostatic and reduces bleeding. It is easy to implant, with a short ischemic time, and lends itself well to a variety of insertion techniques.

How I do it: transapical cannulation for acute type-A aortic dissection.

Aortic dissection is the most frequently diagnosed lethal disease of the aorta. Half of all patients with acute type-A aortic dissection die within 48 hours of presentation. There is still debate as to the optimal site of arterial cannulation for establishing cardiopulmonary bypass in patients with type-A aortic dissection. Femoral artery cannulation with retrograde perfusion is the most common method but because of the risk of malperfusion of vital organs and atheroembolism related to it different sites such as the axillary artery, the innominate artery and the aortic arch are used. Cannulation of these sites is not without risks of atheroembolism, neurovascular complications and can be time consuming. Another yet to be popularised option is the transapical aortic cannulation (TAC) described in this article. TAC consists of the insertion of the arterial cannula through the apex of the left ventricle and the aortic valve to lie in the sinus of Valsalva. Trans-oesophageal guidance is necessary to ensure correct placement of the cannula. TAC is an excellent method of establishing cardiopulmonary bypass as it is quick, provides a more physiological method of delivering antegrade arterial flow and is the only method to assure perfusion of the true lumen.

Predictors of outcome in patients with congenital diaphragmatic hernia requiring extracorporeal membrane oxygenation.

BACKGROUND: The role of extracorporeal membrane oxygenation (ECMO) in patients with congenital diaphragmatic hernia is still evolving. The use of ECMO is invasive with potential complications during instrumentation for cannulation and heparinization. There are no reliable predictors of outcome in patients requiring ECMO. We aimed to identify (a) the factors that could predict outcome and (b) the incidence and relation of complications during ECMO to outcome. METHODS: "Pre" ECMO (age, sex, birth weight, blood gasses, and ventilator settings) and "on" ECMO variables (mode of ECMO, use of nitric oxide, surfactant, liquid ventilation, inotropes, timing of repair, and complications on ECMO) were analyzed to identify predictors of outcome. RESULTS: Fifty-two patients were included. The overall survival was 58%. Mean duration of ECMO (181 +/- 120 vs 317 +/- 156 hours, P = .001), use of nitric oxide (6 vs 10, P = .049), and renal complications (4 vs 14; P < .001) differed between survivors and nonsurvivors. The survival of patients requiring ECMO support for more than 2 weeks is significantly lower than that of patients requiring ECMO support for less than 2 weeks (18% vs 68%, P = .005). Multiple logistic regression revealed ECMO duration of 2 weeks or more and renal complications to be associated with mortality. CONCLUSION: No pre-ECMO variable could be identified as predictor of mortality. Prolonged duration of ECMO and renal complications on ECMO were independently associated with mortality.

A comparison of radiographic signs of pulmonary inflammation during ECMO between silicon and poly-methyl pentene oxygenators.

INTRODUCTION: The inflammatory response caused by extracorporeal membrane oxygenation (ECMO) is clearly visible within the first 24 h of cannulation. The inflammatory process affects all areas of the lung, even areas previously spared by the primary disease. OBJECTIVE: To compare the change in the radiographic signs of inflammatory response to ECMO between poly-methyl pentene and silicon oxygenators. STUDY DESIGN: Retrospective review of neonates and adults pre- and post-replacement of silicon oxygenators with poly-methyl pentene devices. Data were collected from Extracorporeal Life Support Organisation (ELSO) registry forms and patient records. Results were analysed by quantitative and semi-quantitative methods. RESULTS: There was a significant reduction in the radiographic signs of inflammatory response to ECMO, and a reduction in the time taken to revert to pre-ECMO state in the neonatal poly-methyl pentene group compared to silicon. However, there was no significant reduction in the duration of ECMO runs and the percentage survival between these groups in the neonates. In adults, there was no difference in severity of radiographic signs between groups. However, the inflammatory changes were relatively delayed in the adult poly-methyl pentene group. CONCLUSION: Polymethyl pentene (Medos) oxygenators have reduced the host's response phenomenon 'white out' in neonates, and caused a delayed response in adults. This is most likely a consequence of smaller blood contact surface area combined with the effect of heparin coating of the oxygenator membrane. However, recovery was not a function of the type of gas exchange device used.

Tube-graft inversion for the construction of an "open" distal anastomosis during ascending aortic replacement: a new technique.

For the construction of a distal "open" anastomosis during ascending aortic replacement, a tube-graft is placed opposite to the transected aorta. We describe an alternative technique. The tube-graft is inverted and positioned within the aortic arch in a way that brings the entire circumference of the distal end of the tube-graft next to the circumference of the transected aorta. An end-to-end anastomosis is then fashioned with a running suture, the needle of which goes through the aorta and the tube-graft in a single pass. This technique permits easy, accurate, and fast suture placement, producing a hemostatic distal anastomosis within a short circulatory arrest time.

Edge-to-edge repair with mitral annuloplasty for Barlow's disease.

BACKGROUND: The purpose of this study was to define the early and midterm results obtained after the use of edge-to-edge repair with mitral annuloplasty in the setting of Barlow's disease. METHODS: Between 1998 and 2004, 41 patients having Barlow's disease had an edge-to-edge repair creating a double-lumen mitral valve orifice in our unit. In 38 patients (93%), an annuloplasty band was also inserted. RESULTS: Preoperatively, all patients had severe mitral regurgitation (MR), 12 were in New York Heart Association (NYHA) class I, 15 in class II, and 14 in class III. One patient died in hospital (2.4%) and 5 experienced complications (12.5%). There were no late deaths. At follow-up, 2 patients had severe MR and underwent valve replacement, 1 exhibited moderate MR, and 5 had mild MR. Kaplan-Meier 5-year survival, freedom from reoperation and recurrent moderate-severe MR was 97.6% +/- 2.4%, 94% +/- 4.4%, and 90.6% +/- 5.1%, respectively. At latest echocardiographic evaluation (mean 35 +/- 12 months) the mean left ventricular end-systolic and end-diastolic diameters, and the mitral valve area decreased (p = 0.0001) compared with baseline. The mean mitral valve gradient increased (p = 0.001) without clinical evidence of mitral stenosis whereas ejection fraction did not change. Currently, 35 patients are in NYHA class I and 5 are in class II. CONCLUSIONS: In the setting of Barlow's disease, use of edge-to-edge repair with mitral annuloplasty is safe and provides lasting restoration of mitral valve competence with measurable hemodynamic and clinical benefits. In our unit, it is the procedure of choice for correction of MR in patients having Barlow's disease.

Successful use of venovenous extracorporeal membrane oxygenation in accidental hypothermic cardiac arrest.

Cardiopulmonary bypass is usually used for rewarming and for providing cardiac support in patients with severe hypothermia and cardiovascular instability. We report the first case of accidental severe hypothermia associated with prolonged cardiac arrest that was successfully managed by venovenous extracorporeal membrane oxygenation.

Performance of polymethyl pentene oxygenators for neonatal extracorporeal membrane oxygenation: a comparison with silicone membrane oxygenators.

OBJECTIVE: To review the performance of polymethyl pentene versus silicone oxygenators in terms of efficiency in priming and oxygenation, oxygenator resistance, requirements for coagulation proteins and consumption of blood products, for neonatal extracorporeal membrane oxygenation (ECMO) patients. STUDY DESIGN: Forty consecutive neonates were selected retrospectively pre- and post-introduction of the new polymethyl pentene (PMP) oxygenators. They formed two equal groups. After calculation of the sample size, data were collected from ELSO registry forms and patient records. Results were analysed using parametric and non-parametric tests. RESULTS: Neonatal PMP (N-PMP) oxygenators were smaller, faster and easier to prime. They were less efficient than silicone oxygenators, especially in carbon dioxide elimination, and, therefore, required higher sweeps. The preservation of coagulation proteins was significantly better, but there was no reduction in the consumption of blood products, despite having less than half the surface area and significantly lower blood path resistance. CONCLUSION: Small PMP oxygenators (Medos Hilite 800 LT) provide adequate gas exchange and offer technical advantages in terms of more efficient priming, reduced haemodynamic resistance and better control and preservation of coagulation proteins than silicone oxygenators.

A potential propensity for failure secondary to clot embolism in neonatal ECMO.

OBJECTIVE: To report a single case of oxygenator failure caused by clot embolism originating from the bladder; and to discuss some preventative options. CASE REPORT: A 2.5 kg neonate with a diagnosis of influenza A received veno-arterial (V-A) extracorporeal membrane oxygenation (ECMO) for cardiorespiratory support. Halfway through treatment, she underwent an elective circuit change for numerous clots in her circuit. The patient continued to consume vast quantities of platelets and developed a fatal oxygenator failure after 18 days. DISCUSSION: Amongst the factors influencing the outcome in events of a sudden unexpected oxygenator failure are the severity of patient illness, the size of the clot relative to the size of the oxygenator, the availability of a previously primed circuit and the ease and speed of priming a new oxygenator. CONCLUSION: There is a need for improvement in the design of small oxygenators and ECMO circuits. Adjustment of the coagulation parameters and lowering the tolerance towards clots in the circuit by electively changing them may reduce the incidence of sudden unexpected oxygenator failure. However, using a slightly larger Medos oxygenator may gain valuable time needed to arrange an oxygenator/circuit change.

Poly-methyl pentene oxygenators have improved gas exchange capability and reduced transfusion requirements in adult extracorporeal membrane oxygenation.

The performance of poly-methyl pentene (PMP) oxygenators (Medos Hilite 7000LT) was compared with that of silicone membrane (SM) oxygenators (Medtronic 1-4500-2A) for adult extracorporeal membrane oxygenation (ECMO). Forty consecutive patients were selected retrospectively pre- and post-introduction of PMP oxygenators. They were selected according to the dates they received ECMO and were separated into two equal groups with similar backgrounds. The flow path resistance, gas and heat exchange efficiency, consumption of coagulation factors and platelets, blood transfusion requirements, and incidence of clots for each oxygenator type was assessed. Adult PMP oxygenators showed lower blood path resistance than SM oxygenators. However, lower consumption of blood products in these oxygenators was a direct result of their smaller surface area and heparin coated design, reducing contact activation of coagulation factors. These oxygenators are noticeably smaller, require lower priming volumes, and have better gas exchange capability than SM oxygenators. They showed greater stability and preservation of coagulation factors and platelets compared with SM oxygenators. They also had the advantage of a functioning integrated heat exchanger. Using a single PMP oxygenator in the first instance may be adequate for the majority of patients and would significantly reduce red blood cell consumption during ECMO.

Use of stentless xenografts in the aortic position: determinants of early and late outcome.

BACKGROUND: Whether to perform a stentless aortic valve replacement (AVR) is not well established. Our aim was to determine the outcome after AVR with stentless xenograft valves. METHODS: Between 1996 and 2001, a total of 404 patients (mean age 70.4 years) underwent a stentless AVR by one surgeon in our unit. Concomitant procedures were performed in 132 patients (33%). Twenty patients (6.4%) had undergone previous AVR. Eleven types of stentless xenograft valves were implanted: Medtronic Freestyle in 221 patients (55%), Shelhigh in 55 (14%), Shelhigh composite conduit in 33 (8%), Sorin in 26 (6%), Cryolife O'Brien in 25 (6%), Aortech-Elan in 17 (4%), Edwards Prima in 14 (4%), Toronto SPV in 7 (2%), and other valves in 6 (1%). A subcoronary implantation technique was used in 302 cases (76%), complete root replacement in 62 (15%), and a modified Bentall-De Bono procedure in 33 (8%). Mean follow-up was 19.4 months (range, 1.2 to 60.6 months). RESULTS: Overall hospital mortality was 4.2%. This was 2.4% for isolated AVR, 3.6% for AVR and coronary artery bypass grafting, 5.5% for replacement of two or more valves, and 12% for the modified Bentall procedure. On multiple logistic regression redo cardiac operation (p = 0.0006), cardiogenic shock (p = 0.001), left ventricular ejection fraction less than 0.30 (p = 0.01), modified Bentall procedure (p = 0.03), and endocarditis (p = 0.04) were predictors of in-hospital death. Five-year freedom from thromboembolism, hemorrhage, prosthetic endocarditis, structural valve deterioration, and reoperation was 97%, 99%, 99%, 98%, and 96%, respectively. Kaplan-Meier survival at 5 years was 88%. On Cox regression, cardiogenic shock (p = 0.001) and older age (p = 0.03) were adverse predictors of survival. At echocardiographic examination within 6 months from the operation, mean aortic valve gradients were 15 +/- 6 mm Hg, 12.8 +/- 3 mm Hg, 10.8 +/- 4 mm Hg, 9.3 +/- 3 mm Hg, 9.1 +/- 4 mm Hg, and 8.2 +/- 3 mm Hg for valve sizes of 19, 21, 23, 25, 27, and 29 mm, respectively. CONCLUSIONS: The availability of several stentless valve designs facilitates the surgical treatment of diverse aortic valve or root diseases with encouraging early and mid-term results. Patients requiring concomitant procedures may also benefit from the excellent hemodynamic characteristics of a stentless valve. We consider stentless AVR the treatment of choice for patients older than 60 years and those having small aortic roots.