Bioprosthetic replacement of the ascending thoracic aorta: what are the options?

Increasing patient age and improved durability of latest generation bioprostheses have stimulated the use of bioprosthetic devices in the setting of ascending aortic replacement as an alternative to mechanical valved conduits or aortic valve-sparing procedures. We performed an English literature review to assess different surgical options that have been described for bioprosthetic replacement of the ascending aorta. Reported options include: (1) composite valved conduits using a stented bioprosthesis; (2) composite valved conduits using a stentless bioprosthesis; (3) total xenopericardial valved conduits. Composite valved grafts using stented bioprostheses offer a safe and durable option for bioprosthetic replacement of the ascending aorta. Other options are of more recent use and await medium-term results.

[Pathobiology of idiopathic ascending aortic aneurysms]. / Physiopathologie des anévrismes idiopathiques de l'aorte thoracique ascendante.

BACKGROUND: The majority of ascending aortic aneurysms cannot be related to any specific etiology and should be qualified as idiopathic. The incidence of this disease is increasing in the population of the developed countries but its pathobiology is poorly understood. AIM: This article is reviewing the publications concerning the pathobiology of idiopathic ascending aortic aneurysms. SOURCES: A PubMed search on articles published in English or French, between January 1965 and December 2007, on key-words << aortic root >>, << ascending aorta >>, << aortic arch >>, << thoracic aorta >>, << aneurysm >>, << dilatation >> and << dissection >> was undertaken. Articles on aneurysms related to inflammatory and infectious diseases, congenital or genetic syndromes were excluded. RESULTS: The presented data suggests that destructive remodeling of the aortic wall, inflammation and angiogenesis, biomechanical wall stress, and molecular genetics are relevant mechanisms of idiopathic ascending aortic aneurysm formation and progression. LIMITS: Sparse data available from few direct studies offer limited knowledge on pathobiology of idiopathic ascending aortic aneurysms. CONCLUSION: A more intimate knowledge of the triggers and perpetrating factors of this disease might offer new diagnostic and treatment options.

Kinetic assisted venous drainage for orthotopic heart transplantation in patients under mechanical circulatory support: a double-edged sword.

BACKGROUND: Heart transplantation in patients supported with ventricular assist devices (VADs) entails a high risk of injury at resternotomy. Prior femorofemoral bypass is the preferred approach in these patients, but poor venous drainage may restrict arterial flow rate. PATIENTS AND METHODS: We compared bypass parameters, transfusion requirements and postoperative outcome in 33 consecutive patients (40.4+/-12.2 years old, 28 men) assisted with the Thoratec paracorporeal VAD (mean duration, 3.0+/-2.96 months) undergoing transplantation using either gravity siphon drainage (GSD, n=16) or kinetic assisted venous drainage (KAVD, n=17). RESULTS: Cannulation technique, perfusion pressure, temperature and duration were similar between groups. There were no significant differences in arterial re-infusion flow rates (GSD, 3.6+/-0.7 vs KAVD, 3.8+/-0.6l/min, p=0.5). KAVD patients had a lower mean S(v)O(2) and a higher desaturation index than GSD patients (69.5+/-4.6 vs 76.1+/-5.4mmHg, p=0.004; and 0.63+/-0.23 vs 0.25+/-0.63, p=0.0001, respectively). Perioperative requirements in fresh frozen plasma and platelet transfusions were significantly higher in KAVD patients. However, there were no differences in postoperative patient outcome. CONCLUSION: Perceived benefits on venous return associated with KAVD do not necessarily translate into improved arterial re-infusion flow rates and should be weighed against the hazards of increased venous air aspiration and blood product requirements.

Heterogeneity in the remodeling of aneurysms of the ascending aorta with tricuspid aortic valves.

OBJECTIVES: The study addresses mechanisms driving the formation of ascending aortic aneurysms by comparing the maximal dilatation area with the transition area immediately adjacent to the normal aortic tissue left in place during surgical repair. METHODS: Aortic wall specimens were taken from the maximal dilatation area and transition area in 10 patients undergoing surgery for ascending aortic aneurysms and fixed for histology and immunohistochemistry for vascular smooth muscle cells (alpha-actin), endothelial cells (CD31), and macrophages (CD68). Tissue concentrations of vascular endothelial growth factor, matrix metalloproteinase-2, and matrix metalloproteinase-9 were determined by enzyme-linked immunosorbent assay. The results are expressed as medians with their 25th and 75th centiles. RESULTS: Vascular smooth muscle cells were significantly more abundant in the maximal dilatation area than in the transition area (20.3 [14.8-24.4]/10(-2) mm2 vs 8.0 [6.4-9.3]/10(-2) mm2, respectively, P = .002). In the maximal dilatation area, vascular smooth muscle cells had lost their typical lamellar organization, whereas it was preserved in the transition area. Microvessels were significantly more abundant in the media of transition area than in the maximal dilatation area (7.5 [2.9-10.1]/mm2 vs 1.75 [1.5-2.0]/mm2, respectively, P = .008) and were associated with an inflammatory cell infiltration that predominated in their immediate vicinity. There were no significant differences in vascular endothelial growth factor, matrix metalloproteinase-2, and matrix metalloproteinase-9 between both areas. CONCLUSIONS: The transition area appears as a disease progression front characterized by microvessel formation and inflammatory cell infiltration. In contrast, increased vascular smooth muscle cell density in the maximal dilatation area suggests a healing process, although inefficient to prevent aortic dilatation.

Pathobiology of idiopathic ascending aortic aneurysms.

The majority of ascending aortic aneurysms cannot be related to any specific etiology and should be qualified as idiopathic. The pathobiology of ascending aortic aneurysms remains incompletely understood. Data from direct study are still scarce and often limited because of patient heterogenicity. Currently available information suggests that destructive remodeling of the aortic wall, inflammation and angiogenesis, biomechanical wall stress, and molecular genetics are relevant mechanisms of idiopathic ascending aortic aneurysm formation and progression. Further understanding of these mechanisms will likely provide novel diagnostic, prognostic, and therapeutical tools for the clinician.

Computer-assisted coronary surgery: lessons from an initial experience.

Robotic-enhanced coronary surgery has been performed on sixty consecutive unselected patients (60.8+/-12 years) requiring CABG only. Nine had single-vessel (LAD), 13 double-vessel, and 38 triple-vessel disease. Since the endostabilizer was made available in the autumn of 2002 only, the first 47 patients were proposed to have closed chest LIMA dissection only. This was achieved successfully in all but one patient. In addition, 12 distal anastomosis have been performed after full sternotomy with the robot. Every other anastomosis has been hand sewn. The last 13 patients were TECAB candidates. After successful LIMA harvesting, LIMA to LAD suture has been attempted in totally closed chest on the beating heart: it has been successful in two only, the remaining lesions (a total of three) being dilated and stented the day after surgery. In the other 11 patients, the coronary anastomosis was hand sewn after full sternotomy. This suggests that the difficulties in anastomosing small vessels with a standard suture technique jeopardizes the reproducibility of the technique and that further technological developments are needed, to make robotic surgery safe and attractive for the patients.

Platelet activation and aggregation profile in prolonged external ventricular support.

BACKGROUND: Platelet function plays a major role in the understanding of thromboembolic events in prolonged mechanical support. We studied the platelet activation, platelet aggregation profile, and efficacy of aspirin in patients in whom an external ventricular assist device had been implanted. PATIENTS AND METHODS: Fifteen patients were studied prospectively up to 6 weeks after implantation of the same type of ventricular assist device. Platelet function was studied weekly before daily aspirin administration. Aspirin efficacy was tested ex vivo by measuring platelet aggregation triggered by arachidonic acid. Flow cytometry was used to quantify the spontaneous and induced (adenosine diphosphate stimulation) expression of glycoproteins alphaIIbbeta3, Ibalpha, and CD62P on platelet membranes. The plasma levels of von Willebrand factor (von Willebrand factor activity and von Willebrand factor antigen) and fibrinogen were also determined. RESULTS: Six of the 15 patients (26%) maintained an arachidonic acid-induced platelet aggregation despite daily aspirin treatment (250 mg). CD62P values remained increased during a 5-week postoperative period. Spontaneous levels of glycoproteins alphaIIbbeta3 and Ibalpha on platelet membranes remained within a normal range with a preserved reactivity. The plasma levels of fibrinogen and von Willebrand factor remained increased during the entire study period. CONCLUSION: In patients with an implanted external ventricular assist device, the platelet activation profile displays a persistent activation with a preserved reactivity associated with a persistent high inflammatory state and endothelial activation.

Long-term results of the bentall operation versus separate replacement of the ascending aorta and aortic valve.

BACKGROUND AND AIMS OF THE STUDY: Aortic valve disease associated with ascending aorta dilatation can be treated either by separate replacement of the aortic valve and ascending aorta, or by a composite valved graft. METHODS: Between 1974 and 1999, 117 patients underwent a Bentall operation (BP), and 63 a separate replacement procedure (SP) of the ascending aorta and aortic valve. Anatomic lesions were dystrophic aneurysm in 79 patients, annuloectasia in 65, chronic dissection in 14, acute dissection in 18, and other etiology in four. Mean follow up was 3.45+/-3.47 and 8.75+/-6.8 years in the BP and SP groups, respectively. RESULTS: Early mortality was 7.7% in the BP group versus 11% in the SP group (p = NS). Actuarial survival at 10 years postoperatively in these groups was respectively 77.7+/-5.6% versus 75.8+/-6.9% (p = NS). However, freedom from late complication of the ascending aorta was significantly different (97.3+/-1.9% versus 68.3+/-9.0% at 10 years postoperatively). SP was identified as a risk factor for late complication of the ascending aorta by multivariate analysis (p = 0.01; odds ratio = 9). No statistical difference was observed on late reoperation rates. CONCLUSION: Separate replacement of the ascending aorta and aortic valve carries a higher complication rate for the remaining ascending aorta on long-term follow up when compared with the Bentall procedure. However, there were no differences in terms of late mortality.

Long-term follow-up of Thoratec ventricular assist device bridge-to-recovery patients successfully removed from support after recovery of ventricular function.

BACKGROUND: In certain forms of severe heart failure there is sufficient improvement in cardiac function during ventricular assist device (VAD) support to allow removal of the device. However, it is critical to know whether there is sustained recovery of the heart and long-term patient survival if VAD bridging to recovery is to be considered over the option of transplantation. METHODS: To determine long-term outcome of survivors of VAD bridge-to-recovery procedures, we retrospectively evaluated 22 patients with non-ischemic heart failure successfully weaned from the Thoratec left ventricular assist device (LVAD) or biventricular assist device (BVAD) after recovery of ventricular function at 14 medical centers. All patients were in imminent risk of dying and were selected for VAD support using standard bridge-to-transplant requirements. There were 12 females and 10 males with an average age of 32 (range, 12-49). The etiologies were 12 with myocarditis, 7 with cardiomyopathies (4 post-partum [PPCM], 1 viral [VCM], and 2 idiopathic [IDCM]), and 3 with a combination of myocarditis and cardiomyopathy. BVADs were used in 13 patients and isolated LVADs in 9 patients, for an average duration of 57 days (range, 11-190 days), before return of ventricular function and successful weaning from the device. Post-VAD survival was compared with 43 VAD bridge-to-transplant patients with the same etiologies who underwent cardiac transplantation instead of device weaning. RESULTS: Nineteen of the 22 patients are currently alive. Three patients required heart transplantation, 1 within 1 day, 2 at 12 and 13 months post-weaning, and 2 died at 2.5 and 6 months. The remaining 17 patients are alive with their native hearts after an average of 3.2 years (range, 1.2-10 years). The actuarial survival of native hearts (transplant-free survival) post-VAD support is 86% at 1 year and 77% at 5 years, which was not significantly different (p = 0.94) from that of post-VAD transplanted patients, also at 86% and 77%, respectively. CONCLUSIONS: Long-term survival for bridge-to-recovery with VADs for acute cardiomyopathies and myocarditis is equivalent to that for cardiac transplantation. Recovery of the native heart, which can take weeks to months of VAD support, is the most desirable clinical outcome and should be actively sought, with transplantation used only after recovery of ventricular function has been ruled out.